setting standardsTHE LATEST DEVELOPMENTS IN CLINICAL MICROBIOLOGY

Our new look Setting Standards brings you the latest on Oxoid products and news, including • Oxoid M.I.C.Evaluator Strips, the easyand accurate system for MIC testing • IMAGEN hMPV for rapid detection of the human metapneumovirus • IDEIA Hp StAR products forthe diagnosis of H. pylori infection • Read why an independent study recommends Oxoid Chromogenic Candida Agar • Find out thelatest on reducing the impact of norovirus on hospital wards • Hear about the achievements of the winners of the 2006/7 InfectionControl Team of the Year Awards • Read of Oxoid support for charitable work in Romania, promoting higher standards of healthcare.

ISSUE 12

Welcometo the new look Setting Standards

The aim of this newsletter is to keep youup-to-date with what is happening atOxoid, and to share information on thewider world of microbiology. We hope thatyou find it interesting and informative, butwe’d like to make it even better – and forthat we need your help. Please spare a fewminutes to complete our reader survey onthe inside back page of this issue - yourfeedback will help us ensure that SettingStandards continues to be an enjoyable andinformative read.

So, what else is new atOxoid?

As you will no doubt be aware, lastNovember, Oxoid’s parent, Fisher ScientificInternational, merged with Thermo Electronto create the world’s leading scientificsupply company, Thermo Fisher Scientific.

The Oxoid and Remel brands are nowcombined into a specialist business unitfor Microbiology within the Thermo FisherAnalytical Technologies Group. This new,elevated status acknowledges the impor-tance of microbiology to Thermo Fisher. Italso allows us to combine our expertiseand experience to bring new solutions tomicrobiology problems. The Oxoid andRemel R&D and Marketing teams areworking together to identify areas in whichwe can bring new technologies and greaterconvenience to the microbiology laboratory.We know that being part of a much larger,laboratory-focused organisation will bringmany advantages to you in the future.

For now, it’s business as usual; the Oxoidteam is still "Dedicated to Microbiology"and to meeting the every day needs of yourlaboratory. Thanks for all your continuedsupport – and please do help us to makeSetting Standards even better by completingour reply-paid survey.

With very best wishes

Ali Ball,Marketing & Distributor Sales Director

Accurate & Easy Determination of MIC Values with Oxoid M.I.C.Evaluator StripsThe ability of bacteria to adapt in response to selective pressure isan increasing challenge for clinical microbiologists.

Whilst it cannot be denied that the discovery and mass

production of antibiotics has been a significant advance in

improving the health and life expectancy of both humans

and animals, it is ironic that the very use of such agents

actively selects for the proliferation of resistant strains

within the bacterial population. In fact, it was just four

years after penicillin became widely available that resistant

strains of Staphylococcus aureus began to appear and,

unfortunately, similar developments have been witnessed

with other organisms and many new compounds.

To further complicate matters, resistance is often easily

transferable, both within and between species, making it

difficult to accurately predict the response of bacteria to antibiotics. Some organisms,

known as multi-drug resistant strains, have even acquired resistance to a number of

different antibiotic groups.

The role of the clinical microbiologist, therefore, is not only to identify the organisms

responsible for serious infections, but also to assess their susceptibility to a range of

antibiotic agents and to provide information that allows clinicians to predict accurately

the bacteriologic response to, and clinical outcome of, antibiotic therapy. The administration

of targeted antibiotic therapy, at the correct dose and at the earliest opportunity, will

significantly improve the prognosis for the patient.

Disc diffusionThe disc diffusion method is one of the most widely used susceptibilitytesting methods worldwide. It is a simple technique with visual controlsand complete flexibility in the compounds selected for testing at a relatively low cost. Antibiotic-impregnated paper discs are placed onpre-inoculated agar media, such as Oxoid Iso-Sensitest Agar or MuellerHinton Agar, designed to support the growth of a wide range of micro-organisms and not to interfere with the activity of the antibiotic com-pounds. Upon incubation, the antibiotics diffuse from the discs into thesurrounding agar, forming a concentration gradient to which the testorganism is exposed. The organism is categorised as Sensitive,Intermediate or Resistant (SIR) to the antibiotics tested according tothe size of the zone of inhibition surrounding each disc compared torecognized standards (Figure 1).

In order to obtain accurate and reproducible results, however, it isimportant to standardise variables such as inoculum density, medium(e.g. pH, depth and composition), incubation (e.g. time, temperature and atmospheric conditions) and disc content. Guidelines for standardi-sation are provided by internationally recognised bodies, such as theClinical Laboratory Standards Institute (CLSI), the British Society for Antimicrobial Chemotherapy (BSAC) and Deutsches Institut für Normung (DIN).

As a visual technique, disc diffusion offers a number of advantagesover some alternative methods:1 Growth on the plate gives a clear indication of inoculum level (a key

factor for influencing results)1 Contamination, which can confuse results in other methods, is

readily visible on the plate1 ß-lactamase activity is relatively easy to see1 Interactions between antibiotics in adjacent discs, such as synergy

or antagonism, are easily seen1 The presence of resistant mutants within the inoculum can be

detected.

Disc diffusion is a valuable and highly flexible method for susceptibilitytesting, but it is purely qualitative, and there are certain clinicalsituations where a quantitative result may be required (see below). Inaddition, some compounds diffuse poorly through the medium, givinglittle correlation between the zones of inhibition and the minimuminhibitory concentration (MIC), causing some resistance mechanismsto go undetected e.g. glycopeptide resistance. For these reasons, discdiffusion is often supplemented with another AST technique for specificproblem situations.

Breakpoint testingThe breakpoint testing method is a popular technique with larger laboratories because of its suitability for multiple sample testing. It isperformed by adding a defined concentration of antibiotic to an agarmedium. The test organism is inoculated and, following incubation, isdetermined to be sensitive or resistant to that level of compoundaccording to the growth (or lack of growth) observed.

Methods of susceptibility testing

Antimicrobial Susceptibility Testing (AST) is, therefore, one of the most important tasks carried out in clinical microbiology laboratories today. Methodsfor performing this function have been refined and standardised over the years, and there now exists a number of methods by which the susceptibility of organisms to antibiotics can be reliably determined.

The ease of standardisation and automation of this method make it idealfor multiple sample testing if a multipoint inoculator is used.

Since the antibiotic is evenly distributed throughout the agar, thismethod does not present a problem for poorly diffusing compounds.However, it is difficult to detect contamination or to assess inoculumdensity, due to the small amount of sample that is present. Problemsmay also be encountered with compounds that are unstable in solution(requiring small batches of plates to be prepared as required), and thepresence of a swarming Proteus spp. can destroy multiple test results.

The information provided by the breakpoint testing method is relativelylimited - i.e. the result is 'sensitive' or 'resistant' - and subtle changes insusceptibility may not be detected. Where more detailed information isrequired, other techniques are usually employed.

Automated broth micro-dilutionsThe appeal of speed and automation has made rapid, automated sus-ceptibility testing increasingly popular throughout the world. Defined lev-els of antibiotic are stabilised in microtitre wells, covering two or threeconcentrations, usually around the breakpoint where the test organismseither grow or are inhibited by the compound. Specimens are added inliquid medium, and bacterial growth is measured either by detecting turbidity or the hydrolysis of fluorogenic substrates, depending on thesystem in use.

These systems offer the advantages of speed, reproducibility and auto-mated reporting. The panels of agents available are extensive. However,the flexibility to change the content of a panel is limited and costly.Furthermore, the updating of panels and software with new compoundsor amended breakpoints can be extremely time consuming due to validation and registration requirements.

Although the performance of automated broth micro-dilution systemsgenerally correlate well with reference methods, there are some limitationswith certain organism/antibiotic combinations, often relating to shortincubation times. For example, inducible resistance mechanisms needtime to express resistance before they can be detected.

Figure 1: Disc diffusion method

M.I.C.E. strips are easy to applyOn application, the antimicrobial is released into the agar, forming adefined concentration gradient in the area around the strip. After appropriate incubation, a zone of inhibition will have formed around the M.I.C.E. strip. An accurate MIC is easily read as the value in thegraduated box where the growth of the organism touches the strip(Figure 3). This unique box format of the scale reduces subjectivity ininterpretation of the result.

There is also concern that broth dilution techniques are less likely toreflect the clinical situation, since bacteria in vivo will normally multiplyon solid surfaces. Consequently, bacteria grown on solid media aremore likely to behave similarly to bacteria in vivo. This may be significantfor organisms such as Pseudomonas aeruginosa from cystic fibrosispatients. Colonies of this organism often produce a mucoid alginate onagar, but not in broth. This lack of alginate production in a broth canmake the organism appear more susceptible than it would be in reality,since compounds may be deterred in vivo by the exudate.

Minimum Inhibitory Concentration (MIC) testingThe MIC is the minimum concentration of an antibiotic required toinhibit the growth of the test organism over a specified time - usuallyovernight, but it depends on the growth rate of the organism. Unlikeother AST methods, MIC testing generates a quantitative result. Thismay be of greater value in certain clinical situations or in researchsettings, for example:

1 to guide therapy when low-level resistance is suspected

1 to guide therapy in critically ill patients with potentially fatal infec-tions, such as septicaemia, meningitis, pneumonia and endocarditis,or in patients with inaccessible/deep seated infections

1 to monitor the development of resistance during therapy

1 to confirm borderline/unusual results by other methods

1 as an epidemiologic tool to validate empiric therapy

1 to determine in vitro activity of new antimicrobials.

Conventional methods for MIC determination are usually performedusing a range of doubling dilutions incorporated into agar or brothmicro-dilutions. In-house media preparation for these methods istedious, time-consuming and subject to errors. Although products areavailable commercially for traditional MIC testing methodology, there is a simpler and more convenient alternative, utilising an antibiotic gradient stabilised on a polymer strip.

Oxoid M.I.C.EvaluatorTM (M.I.C.E.) StripsOxoid M.I.C.Evaluator (M.I.C.E.) Strips combine the simplicity and easeof use of the diffusion method with the accuracy of an MIC test. Eachstrip provides a gradient of stabilised antimicrobial, covering 15 doublingdilutions, to give an accurate MIC over a range of 256µg/ml to0.016µg/ml (specialist high and low-level concentration strips are alsoavailable for some compounds). The thickness of the M.I.C.E. stripmakes it easy to handle as it is applied to a pre-inoculated agar plate(Figure 2). Furthermore, this helps to minimise the incidence of bubblesbeing trapped under the strip and reduces slipping on the surface of the agar.

Figure 2: M.I.C.E.; easy to apply

Figure 4: individually foil sealed M.I.C.E strips

Accurate determination of MIC using Oxoid M.I.C.Evaluator StripsEach M.I.C.E. strip is individually foil wrapped with desiccant to maintainits integrity until use. This ensures that the quality and performance ofunused strips are preserved and is particularly useful for storing stripsin different locations. Once the sachet is peeled apart, the handle of theM.I.C.E. strip is presented for easy extraction/application. All M.I.C.E.strips are stored at 2-8ºC and are supplied in durable, stackable boxesof 10 or 50 strips.

Figure 3: M.I.C.E.; easy to read

Individually foil sealed M.I.C.E. stripsM.I.C.E are individually foil sealed and on opening the handle of the M.I.C.E.strip is presented for easy extraction/application (Figure 4). The accurateMIC value that is available using M.I.C.Evaluator Strips is invaluable inthe numerous clinical and research settings mentioned previously.This method is simple, precise and easy to implement in any routinemicrobiology laboratory, without the need for investing in additional,complicated equipment.

This article first appeared in Pathology in Practice, May 2007.

M.I.C.E. are currently available in many countries and coming soon inmany more. M.I.C.E. are not available in the USA. For further informationand full details of the range and availability in your country, pleasespeak to your local Oxoid representative, visit www.oxoid.com or tick 1on the reply paid card. REPLY 1

ENCOURAGING A CULTURE OF CHANGE IN ROMANIA

Since the fall of Communism in 1989, the people of Romania havebeen benefiting from expertise freely given by UK health profes-sionals under the auspices of a charity known as Medical Supportin Romania (MSR), which was founded by Patrick Colquhoun.

Following a strategy known as 'narrow focus - wide impact', MSR aimsto promote higher standards of health care and clinical practice inEastern Europe by providing aid and piloting new ideas on a localisedbasis. With help from individuals and companies, including Oxoid, thecharity has been focusing on the provision of training courses, medicalequipment and supplies to Salaj District Hospital in the Romanian townof Zalau which is twinned with Hinchingbrooke Hospital, Cambridge.

Consultant Microbiologists and Laboratory Managers based atCambridge's Addenbrooke's Hospital have travelled regularly to Zalauover the past sixteen years, taking with them consignments of Oxoiddehydrated culture media, AST discs and diagnostic kits. FormerLaboratory Manager Mike Coles, now retired, recalls the conditions heencountered on his first visit to the Romanian hospital in 1992:

“The archaic methodology which I saw being used in the Microbiologylaboratory at Salaj was the same as when I first started work in the UKin 1959”, he says. “They were working with centrally-supplied bottledmedia which had to be melted down in a steamer before use - anapproach which would actually have been familiar to UK microbiologistsas far back as the 1930s. The quality of the media was very poor.”

At this time, the hospital staff who worked in the Romanian laboratorywere aware that their methods were outdated, but had no access tomodern materials, equipment and text books. The 'centralist' and prescriptive environment in which they worked was a legacy ofCommunism, but - thanks to the ongoing efforts of MSR's volunteers -their culture of unquestioningly continuing to do things in time-honouredways is gradually being broken down.

Over the years, the laboratory has been introduced to the benefits ofusing high-quality dehydrated culture media, and significant progresshas been made with enhancing the efficacy of their antimicrobial sus-ceptibility testing. Adoption of standard loop methodology for enumerationof organisms has greatly increased clinical confidence in the value ofurine microscopy, while provision of a safety cabinet by MSR now minimises the risks to staff engaged in the culturing of TB samples.

Among the most recent visitors from Addenbrooke's to Salaj have beenConsultant Microbiologist, Dr Mark Farrington, and Laboratory Manager,Neil Bentley. They describe other successful MSR initiatives in the areaof infection control, including training courses for clinical staff, improve-ments in sharps disposal and plans for the acquisition of plastic-coveredmattresses to replace the unhygienic foam mattresses which had beenused in the hospital's ICU. “Small changes can have a massiveimpact”, comments Neil. “Even if we can just teach people to washtheir hands, our efforts are worthwhile.”

Can you help?If you would like to become a volunteer for Medical Support in Romaniaor contribute in some other way, please visit www.msr.org.uk and leaveyour details, or contact Patrick Colquhoun directly on 01223 276504.

A new, direct immunofluorescence test - IMAGEN™ hMPV - for therapid detection and identification of human metapneumovirus(hMPV) in clinical specimens has just been launched by Oxoid.With results in less than half an hour, and requiring only standardmicrobiological equipment, IMAGEN hMPV enables clinicallaboratories of any size to screen for this important cause ofacute respiratory tract (RT) illness.

First identified in 20011, hMPV is increasingly recognised as a significantcause of respiratory disease in both children and adults2,3 (although it ispredominantly associated with respiratory infections in young children -up to 2 years of age2), causing symptoms that range from mild upperRT illness to more severe lower RT diseases, such as bronchitis,bronchiolitis and pneumonia. Evidence suggests that this virus is animportant human pathogen with a prevalence and clinical significancecomparable to respiratory syncytial virus (RSV)2, and its inclusion inroutine laboratory testing protocols has been recommended4,5.

IMAGEN hMPV is a one-step, direct immunofluorescence technique thatutilises monoclonal antibodies conjugated to a fluorescent dye to detectspecific viral antigens expressed in all strains of hMPV. Following ashort, 15-minute incubation,specimens are mounted on a slide and viewed microscopically using epifluorescent illumination.If hMPV is present, characteristic,bright, apple-green fluorescence is seen within infected cells. This is clearly visible against the red background staining of uninfected cells.

Until now, laboratory diagnosis of hMPV has largely depended on virusisolation in cell culture and/or detection of viral RNA by polymerasechain reaction (PCR)2. These methods are time consuming and requirespecialised equipment, often restricting their use to larger laboratories.The speed and simplicity of IMAGEN hMPV, however, allows laboratorieswithout these specialised facilities to test for hMPV and provides a suit-able routine screening method for clinical laboratories of any size.

IMAGEN hMPV is an important addition to the Oxoid range of productsfor the identification of respiratory viruses. This comprehensive panel oftests helps medical professionals to know what aetiological agent theyare dealing with, and also to understand more about the prevalenceand clinical significance of each of the viruses.

IMAGEN hMPV has demonstrated a specificity of 100% and sensitivityof 76-100% (depending on the reference method used)6. It is availablein kits of 50 tests, including 2 positive control slides and mountingfluid. Other products in the IMAGEN range include direct immunofluo-rescence tests for RSV, influenza A and B viruses, parainfluenza virus 1,2 and 3, and adenovirus.

For more information about IMAGEN hMPV and other IMAGEN tests,please speak to your local Oxoid representative, visit www.oxoid.com ortick 2 on the reply paid card.

References: 1. van den Hoogen, B.G., de Jong, J.C., Groen, J. et al. (2001) Nat. Med. 7:719-724 2. Schildgen, O., Simon, A., Wilkesmann, A. et al. (2006) Rev. Med. Micro. 17:11-25 3. Kahn, J.S.(2006) Clin. Micro. Rev. 19(3):546-557 4. Ordás, J., Boga, J.A., Alvarez-Argüeller, M. et al. (2006) J. Clin. Micro. 44(8):2739-2742 5. Chano, F., Rousseau, C., Laferrière, C. et al. (2005) J. Clin.Micro. 43(11):5520-5525 6. Information on file, Oxoid Limited.

New IMAGEN test for hMPV

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Testing for Clostridium Difficile-Associated Disease (CDAD)

As the reported incidence of CDAD continues to increase rapidly in the UK1 and NorthAmerica2,3 and, with recent outbreaks in other parts of Europe4,5, this major cause of nosocomial diarrhoea is now of worldwide concern.

volume laboratories to offer this service andany size laboratory to perform urgent testing.The simplicity of the test makes it ideal foruse in a near-patient setting, allowing doctorsand nurses to test patients quickly in surgeries,community hospitals and care homes. Suchrapid, 'on the spot' testing may help health-care institutions to limit the spread of disease.

In addition to the Xpect test for C. difficiletoxins A & B, Oxoid also offers the ProSpecT™

C.difficile Toxin A/B Microplate Assay.Requiring less than 5 minutes hands on time,this direct, qualitative enzyme immunoassayrequires only room temperature incubationand provides easy to read results within 2hours. It is one in a range of assays for thedirect detection of enteric pathogens, includ-ing viruses and parasites.

For further information about these testsplease speak to your local Oxoid representa-tive, visit www.oxoid.com or tick 3 on thereply paid card.

References: 1. CDR Weekly (2006) 16(33) 2. McDonald, L.C., Owings, M. and Jernigan, D.B. (2006) Emerging Infectious Diseases 12(3) 3. PHAC (2004) Infectious News in Brief,3rd September 2004. 4. van den Hof, S., van der Kooi, T., van den Berg R., et al. (2006) Eurosurveillance Weekly 11(1) 5. Tachon, M., Cattoen, C., Blanckaert, K. et al. (2006)Eurosurveillance Weekly 11(5) 6. CCDR (1999) Report 25-07 7. Department of Health press release 2003/0222 (2003) (PLCM02003/4, PLCN02003/4) 8. Limaye, A.P., Turgeon,D.K., Cookson, B.T. and Fritche, T.R. (2000) J. Clin. Microbiol. 38(4): 1696-1697 9. van den Berg, R.J., Claas, E.C.J., Oyib, D.H. et al. (2004) J. Clin. Microbiol. 42(3): 1035-1041

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Elderly and immunocompromised patientswho have recently received antibiotic therapyare most at risk of CDAD, and infection canquickly spread throughout hospital wards andother healthcare institutions. Early diagnosis isimportant to ensure the best treatment andcare for patients, to allow prompt isolationand/or cohorting of patients, and to ensureadherence to strict infection control procedures(such as contact precautions and appropriateenvironmental cleaning).

Valuable diagnostic tools for use in the detec-tion of Clostridium difficile-associated disease(CDAD) are now available from Oxoid. TheXpect™ Clostridium difficile Toxin A/B Test isso easy to use that it can be performed in anear-patient or laboratory setting, providing arapid and reliable result in just 20 minutes.This allows appropriate patient care andinfection control procedures to be initiated atthe earliest opportunity.

The Xpect Clostridium difficile Toxin A/B Testallows the direct detection of both C. difficiletoxins A & B in faecal samples. This isimportant since A-/B+ strains of C. difficilehave been linked to CDAD6,7,8,9. To use, dilutedsample is simply mixed with a conjugate andadded to the test cassette. Within 20 minutes,the result is clearly visible and easily inter-preted. No specialised equipment or expertiseis required.

Whereas C. difficile testing was once restrict-ed to larger laboratories, Xpect Clostridiumdifficile Toxin A/B test allows medium to low

Fast and Accurate Diagnosisof InfluenzaOxoid offers a range of products for the detection of flu A & Bviruses. The Xpect® Flu A & B rapid lateral flow test gives resultsin 15 minutes and can be performed in a near-patient or labora-tory setting. The IMAGEN™ Influenza Virus A & B qualitative directimmunofluorescence test can be used for clinical specimens orfor the confirmation and differentiation of Influenza virus A and Bin cell culture. IMAGEN Respiratory Screen contains reagentsagainst a range of respiratory viruses, including Influenza A andB, allowing samples to be screened quickly and cost-effectively.

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most common causal agents of bacteraemiain patients with indwelling medical devicesand are one of the most prevalent causesof blood stream infections in paediatricpatients. With up to 80% of hospital-acquired CNS infections being meticillinresistant, and many species having multipleresistance, a rapid and accurate identifica-tion is important to help direct appropriateantibiotic therapy.

Julie Elston, clinical products applicationmanager at Oxoid, comments, “The seriousnature of bacteraemia means that there islittle time to spare in determining the bestcourse of action. Long delays simply aren'tacceptable and, as a result, the empiric use

of agents such as vancomycin is common.RapID STAPH PLUS gives rapid, same-dayresults, allowing appropriate therapy to be determined more quickly and providing an opportunity for the use of vancomycinto be restricted to when it's absolutely necessary.”

The RapID range includes products for theidentification of:

1 oxidase negative bacteria

1 Enterobacteriaceae

1 anaerobic bacteria

1 Gram-negative glucose non-fermenters

1 Corynebacterium species

1 yeasts and related organisms

1 streptococci and related organisms.

The RapID method is favoured for providingrapid, same-day results1,2,3 (compared toalternative methods that can require 18-72hours) and for being non-automated, allowing even small, routine microbiologylaboratories to adopt this method easily1.

For further information about RapIDSTAPH PLUS or any other RapID product,please speak to your local Oxoid representa-tive, visit www.oxoid.com or tick 4 on thereply paid card.

Identification of Staphylococcal species in under 4 hours

The RapID STAPH PLUS panel incorporatesa series of 18 carefully selected biochemicaltests directed towards this group of organ-isms. The novel, one-step, inoculationmethod allows all of the test wells to beinoculated simultaneously, saving time andsimplifying the procedure. The panel isthen incubated aerobically for just 4 hours.

The clearly visible colour reactions are easyto read and are used to identify the testorganism. Results are interpreted using theRapID STAPH PLUS Differential Chart or byusing the Windows®-based ERIC™

(Electronic RapID Compendium) software.This user-friendly package contains a com-prehensive database of 40 medically impor-tant Staphylococcus species and relatedorganisms, and ranks identifications byprobability (greater than 95% probability isrequired for an identification), ensuringexcellent accuracy and reliability.

RapID STAPH PLUS can be used to identifyStaphylococcus aureus and over 30 speciesof coagulase negative staphylococci (CNS).CNS are an increasingly important cause ofhospital-acquired infections. They are the

N E W P R O D U C T R O U N D - U P

We are pleased to announce the launch of the RapID™ STAPH PLUS kit (product order code:R8311009) for the biochemical identification of Staphylococcus species and related organ-isms isolated from human clinical specimens. This rapid and convenient manual identifica-tion system offers clinical laboratories of any size a valuable, new diagnostic tool for animportant group of opportunistic pathogens, with results in only 4 hours.

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For added assurance, and to meet the regula-tory requirements of accredited laboratories,Stain Control Slides are available for qualitycontrol testing of staining methods. In addition,a Reagent Control Kit, with 30 tests per kit, isavailable for quality control testing of reagentsused in the microbiology laboratory.

Oxoid offers microbiologists a wide selectionof products for the identification and charac-terisation of microbial species, from latexagglutination kits to automated molecularidentification systems. The addition of thesestains and reagents to the range furtherenhances the choice of products offered andallows microbiology laboratories to purchaseeverything that they need for the growth andidentification of micro-organisms from onereliable supplier.

For more information please speak to yourlocal Oxoid representative, visitwww.oxoid.com or tick 5 on the reply paidcard.

N E W P R O D U C T R O U N D - U P

Bactidrop Stains and Reagents Now Available

We have extended our range of products for the identification and classification of micro-organisms with the addition of a wide selection of stains and reagents, includingthe convenient and easy-to-use Bactidrop™ range.

Stains and reagents are used in the identifica-tion and classification of isolated microbialspecies. For convenience and ease of use,Bactidrop stains and reagents are suppliedready-to-use, with 50 ampoules of 0.75ml ineach pack. Each crushable glass ampoule isencased in a protective plastic sheath with adropper dispenser tip. The user is protectedfrom contact with the glass and its contentsby the plastic sheath, and the entire unit issimply and safely disposed of after use.

Stains are available for a selection of stainprocedures, including mycology, fluorescentand Gram staining, and in a variety of sizes,from the Bactidrop format to 250ml bottlesand 3.78 litre bulk containers, to suit theneeds of every laboratory. Reagents such asOxidase and Indole, used in a variety ofmicrobial determination and identificationprocedures, are also supplied in convenient,easy-to-dispense bottles, in addition to theBactidrop format.

Robust New Automatic Air SamplerReliable and Easy to Use

This new addition to the Oxoid range provides users with the choice between preset or user-defined functions. Sample details (e.g. date, time, location, sampled volume and operator ID) canbe stored within the unit or downloaded to a computer (using Oxoid Air Sampler Software) for reporting and trend analysis.

The sampler's plate holders are designed for 55mm or90mm plates, but will accommodate slight variation inplate diameter, providing flexibility. The unit is sup-plied with a 90mm sampling head as standard (a55mm sampling head is available as an optionalaccessory) and is supplied fully calibrated with acalibration certificate traceable to recognisedstandards.

For full details please speak to your local Oxoidrepresentative, visit www.oxoid.com or tick 6 onthe reply paid card.

The new Oxoid Air Sampler is simple to use, compact and easily portable. It is a highspecification, robust instrument for monitoring microbiological air quality at criticallocations within operating theatres, hospital pharmacies and other critical areas whereairborne contaminants could present potential infection problems for patients.

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N E W P R O D U C T R O U N D - U P

Direct Detection of streptococci

Wellcolex Colour Latex Tests for Salmonella, Shigella and E. coli O157

perform and easy to use. An aliquot of colonysuspension or enrichment broth is simplymixed with the latex reagent and, after justtwo minutes rotation, the results are clearly visible. If the test is negative, the latexremains in smooth suspension and retains itsoriginal colour. A positive result is indicated bya distinct colour agglutination against analtered background.

Wellcolex Colour Shigella is used for the identification of Shigella sonnei, S. flexneri,S. dysenteriae and S. boydii. The Wellcolexrange also includes tests for E. coli O157 and H7.

For more information please speak to your local Oxoid representative, visitwww.oxoid.com or tick 7 on the reply paidcard.

PathoDx Strep A Latex Assay is available in 70tests per kit (product order code: R62005) or140 tests per kit (product order code:R62010).

For more information please speak to your local Oxoid representative, visitwww.oxoid.com or tick 8 on the reply paidcard.

Wellcolex Colour Salmonella can be used toeliminate Salmonella-negative samples fromfurther testing. By reducing the number ofsamples requiring further, confirmatory test-ing, this method saves time and resourcesand allows negative results to be reported atleast 24 hours earlier than by conventionalmethods. The test can also be used for thepresumptive identification of Salmonellaserogroups A, B, C, D, E, and G, and the Viantigen using just two reagents. Such informa-tion is useful in the clinical diagnosis ofSalmonella infection and is helpful in themonitoring and control of outbreaks.

In independent evaluations, Wellcolex ColourSalmonella performed extremely well, withhigh sensitivity (100%) and specificity(>98%)1. It was also found to be simple to

The PathoDx Strep A Latex Assay utilises alatex reagent which is highly specific and sensitive to Group A streptococcal (GAS) antigen.The kit is designed to detect minimal numbersof bacteria per swab. It is ready to use with a re-usable reaction slide, colour codedreagents and positive and negative controlswabs included in each kit.

Results are easy to interpret - in the presenceof GAS antigen, the sensitised latex particlesform a distinct and clearly readable, granularagglutination pattern, contrasting with theuniform milky appearance of a negative test.

This highly flexible test allows for 1-minuteantigen extraction to be performed at roomtemperature. The method also allows forextraction at 100°C for maximum sensitivity.The test may also be used for the typing ofbeta-haemolytic streptococcal isolates byconventional culture methods.

The PathoDx® Strep A latex assay is a five-minute latex agglutination slide test for the directdetection of Streptococcus pyogenes Group A antigen from throat swabs. This convenient testcan be performed either in the physician's office or a laboratory setting, offering fast, accuratediagnosis of pharyngitis to ensure optimal patient care.

Wellcolex® Colour tests for Salmonella, Shigella and E. coli O157 utilise simple, colourlatex agglutination technology to provide rapid identification of these micro-organismsto assist in the prompt and appropriate treatment of patients.

Reference: 1. Data on file at Oxoid.REPLY 7

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REDUCING THE IMPACT OF NOROVIRUS

The symptoms of norovirus-associatedgastroenteritis are relatively mild comparedto other gastric infections, but a norovirusoutbreak on a hospital ward can have seri-ous consequences for both patients andhealthcare staff alike. Rapid diagnosis ofoutbreak cases allows early implementationof the most appropriate control measures,which helps contain the outbreak moreeffectively.

Norovirus is the official genus name for thegroup of related, RNA, non-enveloped virusesthat cause acute gastroenteritis in humans1

that were previously referred to as Norwalk-like viruses (NLV), caliciviruses or small roundstructured viruses (SRSV).

The true incidence of norovirus infection isunknown, since many cases in the communitygo unreported. However, it is estimated thatthere may be as many as 23 million cases ofacute gastroenteritis due to norovirus in theUSA annually1 and as many as 1 million casesper year in the UK2. Noroviruses are recog-nised as the most common viral cause ofinfectious gastroenteritis1,2 and are estimatedto account for 89-96% of non-bacterial out-breaks of gastroenteritis3. The disease is aparticular problem in healthcare settingswhere it is reported to be the most commoncause of nosocomial gastroenteritis4, respon-sible for around 63% of outbreaks5,6.

Large outbreaks of norovirus infection arecommon and can be particularly problematicin environments where people are in closeproximity, such as hospitals, nursing homes,schools, hotels and cruise ships2,4. Norovirusoutbreaks tend to involve larger numbers ofpeople than outbreaks of bacterial gastroen-teritis7. It is difficult to quantify the economic

hand hygiene, contact precautions (includingthe use of gloves and aprons), isolation/cohorting of patients where possible, closureof wards to new admissions, exclusion ofaffected staff for 48 hours post-recovery, andrapid cleaning and disinfection of contaminat-ed areas can assist in containment2,4,6,12. It isalso recommended that terminal cleaning ofthe affected area should be performed 72hours post resolution of the last case4.

To prevent the spread of infection to otherclinical areas, additional precautions mayinclude the restriction of staff and patientmovement between affected and unaffectedareas and the dedication of essential staff toaffected wards4. When control measures, suchas earlier ward closure (<4 days), are imple-mented quickly evidence suggests that theimpact of outbreaks is reduced2,5,6.

Diagnosis in the laboratoryA number of clinical features are typical in anorovirus outbreak: incubation 24-48 hours,vomiting in >50% cases, duration 12-60hours, no bacterial agent detected1. However,to justify extreme infection control measures,such as ward closures, and to ensure correctpatient management, identification of theetiological agent is vitally important.

Confirmation of norovirus outbreaks is alsoimportant for epidemiological studies and toimprove our understanding of this group ofviruses. Several methods are available for theidentification of norovirus infection, but feware suitable for screening purposes in routineclinical laboratories.

burden of such outbreaks in the hospital set-ting, but far reaching consequences includeward closures and disruption to many hospitalactivities. One study estimates that, in termsof staff absences and lost bed-days, theannual cost to English hospitals is as high as£115 million5,8.

Highly contagious and easily transmittedNoroviruses are highly contagious and aretransmitted by many routes1,2,4 includingfaecal-oral, vomiting (aerosols and splashes),contaminated food/water, contaminatedenvironment/objects and person to person.With a low infective dose2,9, infection spreads rapidly4.

With an incubation period of 24-48 hours,the disease is characterised by acute-onsetvomiting, diarrhoea, nausea and fever1,2,9.Affecting people of all ages, it is usually mildand self limiting. Complications rarely occur,but dehydration may be experienced,predominantly in very young, elderly orimmunocompromised individuals. Since suchvulnerable groups are particularly affected,infection may be more severe in hospitalisedpersons10.

Immunity to norovirus infection is not long-lasting, probably due to the genetic variabilityof the virus.

Norovirus infections usually peak in wintermonths, hence the popular name 'winter vom-iting disease', although uncharacteristic sum-mer outbreaks have been observed11.

Infection control issuesDue to the ease of transmission of the virusand its ability to survive for long periods in theenvironment2, norovirus outbreaks can be difficult to control and may therefore be longlasting.

A nosocomial outbreak is defined as 2 ormore cases (positive for norovirus) occurringin a functional care unit within 7 days of eachother6. Larger care units and those with higherpatient throughput are considered to be atgreater risk of outbreaks8.

In an outbreak, over 50% of patients on a wardmay be affected4, and it is therefore importantto instigate infection control measures rapidly.Such measures should be designed both tocontain the outbreak at ward level and toprevent spread to other wards. Good

the need to send samples away and wait several days for the role of norovirus to beconfirmed (by which time the outbreak mayhave spread further).

Oxoid IDEIA allows norovirus outbreaks to beconfirmed at the earliest opportunity so thatinfection control measures can be instigatedas soon as possible in order to reduce theimpact of this significant nosocomialpathogen.

For more information please speak to your localOxoid representative, visit www.oxoid.com ortick 9 on the reply paid card.

Electron microscopyNoroviruses can be identified by their charac-teristic morphology using electron microscopy(Figure 1). Whereas this method is able todetect dual or multiple infections, it lacks sensitivity and is not suited to large numbersof samples. As few laboratories have the necessary facilities or expertise to performthis method, it is mainly used for referenceand research purposes.

References 1. CDC Norovirus Technical fact sheet www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm 2. HPAwww.hpa.org.uk/infections/topics_az/norovirus/menu.htm 3. Lopman, B.A., Reacher, M.H., van Duijnhoven, Y. et al. (2003)Emer. Infect. Dis. 9(1) 4. Chadwick, P.R., Beards, G., Brown, D. et al. (2000) J. Hosp. Infect. 45:1-10 5. CDR Weekly (2004)14(47) 6. Lopman, B.A., Reacher, M.H., Vipond, I.B. et al. (2004) Emerg. Infect. Dis. 10(10):1827-1834 7. Widdowson, M.,Sulka, A., Bulens, S.N. et al. (2005) Emerg. Infect. Dis. 11(1):95-102 8. Lopman, B.A., Andrews, N., Sarangi, J. et al. (2005) J.Hosp. Infect. 60(2):135-143 9. US FDA CFSAN Bad Bug Book www.cfsan.fda.gov/~mow/chap34.html 10. Lopman, B.A.,Reacher, M.H., Vipond, I.B. et al. (2004) Clin. Infect. Dis. 39(3):318-324 11. Lopman, B.A., Reacher, M., Gallimore, C. et al.(2003) BMC Public Health 3:13 12. CDC Norovirus in Health Care facilities fact sheetwww.cdc.gov/ncidod/dhqp/id_norovirusFS.html 13. CDC MMWR (2001) 50/No.RR9 14. Vinjé, J., Vennema, H., Maunula, L. etal. (2003) J. Clin. Micro. 41(4):1423-1433 15. Data on file, Oxoid Limited.

SeroconversionThe detection of an increase in specific anti-bodies in acute and convalescent-phase bloodsamples has also been used to detectnorovirus infection. However, as these pairedsera may be several weeks apart, this methodis not suitable for rapid diagnosis.

Molecular methodsReverse transcriptase polymerase chain reaction (RT-PCR) is a commonly used methodfor the identification of norovirus as it is bothsensitive and specific, and able to provide astrain level identification (although this function is not routinely required for patientmanagement).

Its use as a routine screening method isrestricted however, as only larger laboratoriesmay have the facilities to perform RT-PCR.The performance of this method is also influenced by the primer sets used for amplifi-cation. The variability of the norovirus genomemakes it difficult to keep up to date with theprimer set required to detect the virus andsome strains may therefore escape detection13.No single PCR assay will detect all variants ofnorovirus. So, negative stools from patientsmatching the clinical diagnostic criteria wouldneed to be tested with additional primer sets14.

Enzyme immunoassaysAlthough the sensitivity of an ELISA test isless than PCR, the speed and simplicity ofthe method make it a useful and economicscreening tool for the local diagnosis ofnorovirus outbreaks. A proposed algorithmfor the test is shown in figure 2.

Oxoid IDEIA - Results in just 2 hoursThe Oxoid IDEIA™ Norovirus ELISA method is more broadly reactive than PCR, with sensi-tivity towards the two main norovirusgenogroups involved in human disease(genogroups 1 and 2). IDEIA Norovirus utilisesspecific monoclonal and polyclonal antibodiesin a solid phase immunoassay to detectnorovirus antigen (which is less variable thanthe norovirus genome) in human faeces.

The current version offers a sensitivity of72.8% and a specificity of 100% comparedto PCR15. Requiring only standard laboratoryequipment, it can be performed quickly andeasily by any laboratory, and is suitable forautomation for high throughput testing.

The far-reaching implications of ward closuresas a result of a norovirus outbreak requireaccurate justification. The simplicity andenhanced performance of the Oxoid IDEIAmethod have brought norovirus testing, andsame-day results, into the capabilities of theroutine clinical laboratory. There is no longer

Figure 1. Characteristic structure of norovirusparticles seen by electron microscopy

Figure 2.

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incubation, the cultures were subcultured onSDA again, and the confirmatory identificationof Candida spp. was achieved using germtube production, carbohydrate assimilationand API.

ResultsThe results obtained showed that 17specimens (6 vaginal swabs, 6 respiratorytracts, 3 blood culutures, 2 urine) had twoCandida spp. isolated, whilst 1 blood culturegrew C. albicans, C. glabrata and C. tropicalis.Candida albicans was the predominantspecies isolated from the samples with dualinfection. Among the 82 samples with singleCandida spp. isolated, the biotypes dependedon the source. Overall, C. albicans was themost common biotype followed by C. glabrataand C. tropicalis.

ConclusionMixed Candida species infection is an emerging trend in systemic Candida infection.It was recommended that OCCA be used as aprimary isolation medium for the rapid andeffective differentiation of clinically importantmixed Candida species.

Reference: 1. Data on file at Oxoid.

Oxoid Chromogenic Candida Agar

Saves Time

1 Presumptive identifications in 48hours

1 Identifies more C. albicans within 24hours than competitor media1

Easy to Interpret

1 Chromogenic colour reactions alloweasy differentiation of Candida spp.

Selective

1 Chloramphenicol inhibits bacterialgrowth, even after prolonged incubation

Benefit to Patients

1 Some Candida species are more likely to be azole-tolerant than others.Early differentiation of species allowsinformed judgements on most appropriate treatment.

For more information about this product,please speak to your local Oxoid representative, visit www.oxoid.com ortick 10 on the reply paid card.

Multi-Candida Species Infection Study recommendsOxoid Chromogenic Candida Agar

The study1 stated that Candida spp. is themost frequent cause of invasive fungal infec-tion in solid organ transplant recipients andHIV infected patients and, whereas Candidabloodstream infections in many parts of theworld are caused by Candida glabrata, inMalaysia, Candida tropicalis and Candidaparapsilosis are the predominant species iso-lated from blood. These infections are associ-ated with high morbidity and mortality. Thereis also concern about emerging drug resistantCandida spp. and the multiple species infec-tion of some patients.

The objective of the Malaysian study wasto investigate the frequency of multipleCandida spp. infection amongst patients atthe University of Malaysia Medical Centre.

MethodFrom January to March 2007, 100 clinicalsamples (47 vaginal swabs, 18 urine, 15blood cultures, 15 respiratory tract samples,5 wound swabs, 1 tissue biopsy, 1 asciticfluid) with positive Candida spp. isolated onSabouraud Dextrose Agar (SDA) were sub-cultured on to Oxoid Chromogenic CandidaAgar (OCCA). The OCCA plates were thenincubated at 30ºC for 48 hours. Following

A recent study undertaken by the Department of Medical Microbiology, Faculty of Medicine,University of Malaya, Kuala Lumpur concluded that Oxoid Chromogenic Candida Agar be used as the primary isolation medium for the rapid and effective differentiation of clinicallyimportant, mixed Candida species.

Mixed Flora C. albicans C. tropicalis

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The judges were unanimous in their decision to award the £5,000first prize in the 2006/2007 Oxoid Infection Control Team of the YearAwards to the team at the Royal Wolverhampton Hospitals NHS Trust.

All judges were impressed by the team's “can do” approach and the wayin which they had gained involvement from the top down by establishingthe Infection Prevention Board as a new sub-group of the Trust Board.They identified sensible performance indicators and targets and recog-nised that the Link Nurse Group was not communicating as efficiently asit could be. They identified leads and champions to provide more effectiveroutes of communication and share best practice in infection control. Inthe words of one of the judges, “These actions ensure that people areanswerable at board level on infection control matters and that there arenow no loose ends”.

Key initiatives had also achieved success. MRSA bacteraemia ratesfell, multi-faceted initiatives to reduce Clostridium difficile associateddiarrhoea (CDAD) were put in place (including a root-cause analysis ofevery case of CDAD), and practice improvements throughout the Trusthave reduced to zero cases of Acinetobacter baumannii colonisation/infection since August 2006.

In summary, one judge commented, “Within a reasonably sized hospital,with a team that is not over resourced, the infection control team at theRoyal Wolverhampton Hospitals NHS Trust are doing what we should allbe doing, and they are doing it well.”

Oxoid Infection Control Team of the Year Awards2006/2007 Winners Announced

With entries from infection control teams from all over the world and with each hospital facing different challenges andhaving widely differing resources at their disposal, choosing the winners of the 2006/2007 Oxoid Infection Control Teamof the Year Awards was a difficult task. The judges once more focused their attention on those teams who had demon-strated that they have really made a difference to standards of infection control within their own hospitals and who aresetting examples for others to follow. The winners were awarded their prizes at a recent Awards Dinner and Ceremony,held to celebrate their achievements. The winners were:

FIRST PRIZE: Royal Wolverhampton Hospitals NHS Trust, UK

The judges were very impressed by the volume of workundertaken and the successes achieved by this small infection control team at the 1,700 bed, Cho Ray Hospital.

The team had produced many educational aids and trained over4,000 people in basic infection control practices during 2006, attheir own and surrounding hospitals. Their intervention pro-grammes, modified procedures and new reporting systemsshowed that hospital-acquired infections had fallen significantlyand, despite an increasing incidence of patients with blood-borneinfections, exposure to these infections amongst staff had beengreatly reduced. The team received a prize of £1,000 and aframed certificate.

SECOND PRIZE: Cho Ray Hospital, Vietnam

Separating two worthy winners was an impossible task for thejudges when it came to awarding 3rd prize. So, they decided to make the award jointly to two hospitals, each of whomreceived £250 and a framed certificate.

The entry from the team in Southampton demonstrated that, acrossfour hospital sites, they had many infection control challenges. Thejudges were impressed by the team's “solid, hot-spot strategy and target indicators”.

The judges commented that the team atthe Aminu Kano Teaching Hospital inNigeria had “a holistic approach toinfection control and had done a wonderful job with limited resources”.Their reducing rates of hospital-acquired infection and procedures fordealing with hospital waste were citedas particular areas of success.

JOINT THIRD PRIZE: Southampton University Hospitals NHS Trust, UK and AminuKano Teaching Hospital, Nigeria

2007/2008 AWARDS NOW OPEN FOR ENTRY The 2007/2008 Oxoid Infection Control Team of the Year Awards are now openfor entry, so make sure that you either ask your local Oxoid representative for details, visit www.oxoid.com or tick 11 on the reply paid card,and next year it could be your team that is featured on these pages!

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The Oxoid range for the detection of Helicobacter pylori infection nowincludes IDEIA™ Hp StAR and RAPID Hp StAR™. Unlike serology methods,these stool antigen tests can be used to detect active infection and toconfirm the eradication of H. pylori following antibiotic therapy.

Using a combination of unique amplification technology and monoclonalantibodies, these non-invasive tests detect H. pylori antigen with a highdegree of accuracy and can be used to diagnose current infection inboth adult and paediatric patients.

IDEIA Hp StAR is a highly sensitive and specific ELISA test that is easyto perform using standard equipment, allowing the 'test and treat'policy recommended by the European Helicobacter Study Group1 to beimplemented in routine laboratories. It is suitable for both manual andautomated testing and has demonstrated excellent performancewhen compared to the urea breath test and alternative enzymeimmunoassays2,3,4.

RAPID Hp StAR is a rapid immunochromatographicmembrane based assay that provides reliable resultsin just 15 minutes, without the need for specialequipment. The speed and simplicity of this methodmake it suitable for small volume testing within thelaboratory, or for near-patient testing in gastroenterology clinics and doctors' surgeries.Such convenience is ideal for monitoring the efficacy of antimicrobial treatment without the need for return hospital visits.

The Hp StAR test provides a cost effective, non-invasive alternative tothe more extensive invasive methods offered by many hospitals. The testinvolves minimal discomfort for the patient, making them particularlysuitable for paediatric use. Furthermore, the ability to detect active infec-tions also helps to avoid the unnecessary administration of antibiotics.

For further information please speak to your local Oxoid representative,visit www.oxoid.com or tick 12 on the reply paid card.

New Non-invasive Tests for Helicobacter pylori infection

References: 1. Malfertheiner, P. et al. (2002) Aliment. Pharmacol. Ther. 16:167-180 2. Hino, B. et al. (2004) J. Paed. Gastro. and Nutrition 39:519-523 3. Chisholm, S.A. et al. (2004) J. Med. Micro.53:623-627 4. Leodolter, A. et al. (2002) Am. J. Gastro. 97(7)

D E D I C AT E D T O M I C R O B I O L O G Y

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© 2007, Oxoid Ltd.; copyrights to photographs held separately; contact Oxoid Ltd. for details. Photographs may not be extracted or reproduced in any way.

Folio: 1173/09/07

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