View
222
Download
2
Category
Preview:
Citation preview
Identification of Infectious Disease Processes
Ready…Set…Go!Carolyn Fiutem, MT(ASCP), CIC
Infection Prevention Officer, TriHealthOctober 10, 2012
Objectives:
Recognize epidemiologically significant organismsInterpret results of lab testsIdentify indications for biologic monitoring
Fundamental Principles of Infection and Immunity
Colonization – organisms in or on a host; growth but no tissue invasion or damageInfection – entry of an infectious agent in tissues of a host; growth and create symptomsContamination – presence of microorganisms on inanimate objects, skin, or in substances
INFECTIOUS AGENT /Causative AgentA microbial organism with the ability to cause disease. The greater the organism's virulence (ability to grow and multiply), invasiveness (ability to enter tissue) and pathogenicity (ability to cause disease), the greater the possibility that the organism will cause an infection.
RESERVOIRA place within which microorganisms can thrive and reproduce.
PORTAL OF EXITA place of exit providing a way for a microorganism to leave the reservoir.
MODE OF TRANSMISSIONMethod of transfer by which the organism moves or is carried from one place to another.
PORTAL OF ENTRYAn opening allowing the microorganism to enter the host.
SUSCEPTIBLE HOSTA person who cannot resist a microorganism invading the body, multiplying, and resulting in infection. The host is susceptible to the disease, lacking immunity or physical resistance to overcome the invasion by the pathogenic microorganism.
Components of the Infectious Disease Process
Mechanisms of Microbe PathogenicityVirulence
Environmental survival in transitBBP in blood outside the body, Protection against drying, Vectors
Effective mechanism for transmission
Vectors, Motility, Airborne, Fomites
Ability to attachElectrostatic charge, Adhesion
Reproduction/ProliferationEnzymes, Endotoxins, Capsules, Biofilms
Invasion and DisseminationRigid cell wall, Cell surface components, ability to alter cell surface, Deterrents to intracellular killing after phagocytosis
Bacterial ToxinsExotoxins – potent toxin secreted by a bacterial cell
Excreted in environmentGram-positive bacteriaMore susceptible to heatNeutralized by antibodiesEnzymatic activityPVL of MRSA, and Toxins A/B of C. diff
Endotoxin – heat-stable toxin in cell wall; pyrogenic; increase capillary permeability
Surface of GNRsPartially neutralized by antibodiesProduce physiologic changes in hostCholera toxin – fluid in the GI tractE. coli 0157
Cellular ImmunityT-lymphocytes & mononuclear phagocytesOriginate in bone marrowMigrate to thymus fetus/infancyT-cells from spleen, lymph nodes, bone marrowReceptors on surface of T-lymphocytesReview cellular immune response
Cellular Immunity cont.Cytokines
Interleukin – 1: pyrogen, stimulate macrophage chemotaxisInterleukin – 2: made by CD4, enhance NK cell activityInterleukin – 4: made by T-cells and mast cells, stimulate growthInterleukin – 6: pyrogen, B-cell/T-cell differentiationInterferon: made by WBCs & fibroblasts; inhibit virus growth; α, β, γTumor Necrosis Factorcause protein catabolism in host w/ loss of muscle massLymphotoxin: promotes inflammation; stimulates neutrophilsGranulocyte and Monocyte Stimulating Factors - reproduction
T-lymphocytesCD3 surface marker – IDs themCD4 marker – helper lymphocytes for phagocytosis, release cytokines, long-term memory (vaccines)CD8 cells – cytotoxic and suppressor lymphocytesNatural killer cells – lyse tumor & virus infected cells
Humoral Immunity – B-lymphocytesCellular Sources of
AntibodiesPrecursors from fetal liver
and bone marrow to spleen and lymph nodes
Antibody producing plasma cells
Classes of ImmunoglobulinIgG – late occurring in
Immune response (I’ve got it and it’s gone)
IgM – first reacting , present for only ~ 6 months (I’m mopping it up)IgA – secretory antibody, plasma cells in mucous membranesIgD – surface of lymphocytes – antigen specificityIgE – allergy inducing; histamine & inflammatory substances; mucous membranes
Non-specific Host Defenses
Genetic ConstitutionCaucasians, African-Americans, Asians, Alaskan/Hawaiian natives
Mechanical BarriersSkin, mucous membranes, normal flora
Physiological BarriersFever, secretions, motility
Vascular Circulating DefensesNatural/cross-reactive antibodies, fibronectin, estrogens, circulating WBCs
•Activated by contact with IgG or IgM or certain microorganisms•Genetic deficiencies 10
Phagocytic Cell SystemNeutrophils (Polys)
• Most dominant WBC (40-70%)• “First Responder”• Acts against pyogenic (pus-forming)
bacteria• Life expectancy ~ 7 hours in
circulatory system• Large reserve in bone marrow• Leukopenia – can be poor
prognostic indicator• Hypersegmentation – suggest B12
or folate deficiency
Neutrophil RatiosDegenerative Left Shift – increase in bands with no leukocytosis; poor prognosis
Regenerative Left Shift – increase in bands with leukocytosis; good prognosis
Right Shift – few bands with increase in segmented neutrophil seen in liver disease, hemolysis, drugs, cancers, allergies, or megaloblastic anemia
Hypersegmentation – with no bands is seen in megaloblastic anemia and chronic morphine addiction
Myeloid Left Shift – Bands, Metamyelocytes (Metas), Myelocytes, Promyelocytes (Pros), Blasts
Neutropenia• Acute overwhelming bacterial infections – poor
prognosis• Viral infections• Rickettsial and some parasitic diseases• Drugs, chemicals, radiation, toxic chemicals• Anaphylactic shock• Severe renal disease• Sepsis due to E. coli – reduced survival of polys• Hormonal Disorders
Neutropenia in Neonates• Maternal neutropenia• Maternal drug ingestion• Maternal isoimmunization to fetal WBCs• Inborn errors of metabolism (i.e., maple syrup
urine disease)• Immune deficits• Myeloid disorders• Defective intrinsic factor secretion
Absolute WBC CountsRelative Number = percentageAbsolute Count = Percentage X Total WBC Ct.Can have normal WBC count yet be neutropenicNeed to look at WBC count and differentialNormal WBC ranges:
1. Adults ~ 3.5-10, 0002. Newborns ~ 9-30,0003. 2 weeks ~ 5-20,0004. 1 yr ~ 6-18,0005. 4 yr ~ 5500-17,0006. 10 yr ~ 4500 – 13,500
Basophils0-1% of WBCsMast Cells are tissue basophilsSecrete histamine, seratonin, & prostaglandins – increase blood flow to areaHodgkin’s DiseaseParasitic infectionsInflammationAllergySinusitisAfter splenectomyTBSmallpox, ChickenpoxInfluenza
Eosinophils
1-4% of WBCsAre cytotoxicNAACP….NeoplasmAsthma/AllergyAddison’s DiseaseCollagen/Vascular DiseaseParasitic Infections
Lymphocytes
25-40% of WBCsFight viral infectionsPertussisChronic granulomatous diseases, i.e., TBCrohn’s diseaseUlcerative ColitisAddison’s DiseaseBrucellosis
Lymphopenia
ChemotherapyAfter administration of cortisoneObstruction of lymphatic drainage, Whipple’s disease or tumorsHodgkin’s diseaseHIV/AIDSTrauma
Monocytes
Fight severe infection via phagocytosis3-7% of WBCsBacterial infectionsTBSBESyphilisParasitic, fungal, rickettsial diseases
20
Knowledge Check…
Which of the following is not a mechanical barrier?
a. Intact skinb. Mucous membranesc. Secretionsd. Normal bacterial flora
Knowledge Check…
What is the name for a substance that prevents water-soluble elements such as antibiotics and disinfectants form reaching pathogens?
a. Cell wallb. Biofilmc. Sludged. Biocarbon
Knowledge Check…Patients with cell-mediated immunity dysfunction are susceptible to infections attributed to pathogenic intracelluar bacteria. Examples of these organisms include:
1. Salmonella typhi2. Bacteroides fragilis3. Listeria monocytogenes4. Staphylococcus aureus
a. 2,3b. 1,3c. 1,2d. 3,4
Knowledge Check…
Which organism found in food poisoning causes the most rapid onset of symptoms?
a. Salmonella enteritidisb. Shigella sonneic. Staphylococcus aureusd. Escherichia coli
Knowledge check…
The IP is teaching nurses how to assess infection risks in patients. Depletion of what cell type provides the BEST indication of susceptibility to most bacterial infections?
a. Monocyteb. Eosinophilc. Neutrophild. Lymphocyte
Knowledge Check…Your patient has a low absolute neutrophil count. Of the following choices, which is true of your patient?
1. They are especially susceptible to disease.2. You can determine the absolute neutrophil count by
multiplying the total WBC count by the percentage of mature and immature neutrophils.
3. The patient’s WBC count is between 4000 & 10,000.4. The patient’s complement system will only be
activated through the alternate pathwaya. 1b. 1 & 2c. 3d. 1, 2, & 4
Microbiology and the LaboratoryBacteria
Internal structures – familiarityExternal structures – cell wall, glycocalyx, flagella, fimbriae and piliSize/Shape – 0.2-2 u X 2-8 u; cocci, rods, spiralsReplication – cell division every 15-24 hoursGenetic variation
Plasmids found in cytoplasm, circular pieces of DNATransformation – free DNA in cellTransduction – DNA carried by bacteriophage (virus)Conjugation – direct sharing of DNA
Mutations – random base pair substitutionSubmicroscopic bacteria – Mycoplasma, Chlamydiae, Rickettsiae
Fungi
YeastsSingle-celled, budding or fission2-60 uSmooth, creamy coloniesCandida, Cryptococcus
MoldsMultinucleated network of filaments (hyphae)Can reproduce asexually or sexuallyCan reproduce via sporesAspergillus, Rhizopus
Dimorphic fungiGrow as yeast or fungi depending on conditionsMold form at room temp (25°C)Yeast form at body temp (37°C)Histoplasma, Coccidioides, Blastomyces, Paracoccidioides
Viruses, Parasites, PrionsViruses
Replicate only in cells of host/reservoirRNA or DNA in a protein coatClassified using genome, number of strands and presence or absence of envelope
ParasitesBlood - PlasmodiumProtozoa - GiardiaHelminths – pinwormEctoparasites – scabies, lice, bedbugs
PrionsInfectious pieces of proteinsOnly replicate in cells of living organismsNeurotropic Untreatable and universally fatalCreutzfeld- Jakob disease (CJD, vCJD) – transmissible spongiform encephalopathy (TSE) 30
Laboratory TechniquesMicroscopy – light & electronSpecimen Preparation – direct/wet prep, stainsCulture – agar, broth, biphasic, tissueAntimicrobial Susceptibility Testing (AST)Enzyme Immunoassay (EIA)Latex AgglutinationDNA ProbesPolymerase Chain Reaction (PCR)SerologicAnatomic PathologyGeneral Laboratory
Identification of…Bacteria – stains, culture, serology, molecularFungi: yeasts, molds – direct preps, culture, biochemical tests, direct antigen tests, serologyViruses – direct antigen tests, antibody tests, tissue cultureParasites – microscopy, serologyMycobacteria – culture, molecular, direct detection Mycoplasma - serologyChlamydiae – direct antigen testsRickettsiae/Other Tick-borne Microbes – serology, ELISA
Antimicrobial Susceptibility TestsDisk Diffusion – Kirby BauerBroth Dilution – Minimum Inhibitory Concentration (MIC); manual or automatedE-TestBeta-lactamase – penicillins resistanceDisk Approximation – inducible clindamycin resistanceSynergy Test – combinations of antibioticsHodge Test – Extended Spectrum Beta-lactamase in gnrsMinimal Bacteriocidal Concentration (MBC)
Types of ß – lactamases
produced by Enterobacter-
iaceae
Examples Hydrolyzes Inhib by CA
BasicPens
Cephalosporins Cepha-mycins
(FOX, CTE)
Carba-penems
(IMI, MERO)
AZT
I II III IV
Broad Spectrum TEM-1TEM-2SHV-1
Y Y Y/N N N N N N +/+++
Extended Spectrum Beta-
Lactamase
TEM familySHV family
Y Y Y Y Y N N Y ++++
Amp-C ACCCMYCFEDHA
Y Y Y Y Y Y N Y N
Carbapen-Emases(NDM-1)
KPC Y Y Y Y Y Y Y Y +++
IMP, GIM Y Y Y Y Y Y Y Y ++
OXA Y Y Y Y Y Y Y Y +
Gram Negative Beta-lactamases
Courtesy of Dr. Larry Gray
Measures to control resistant organisms
Antibiotic StewardshipSurveillanceAntibiogramsAppropriate use of vaccinesAppropriate transmission-based precautionsHand HygieneBarriers
Antimicrobial Therapy - Susceptibility ReportsTherapy/TreatmentProphylactic TherapyEmpiric Therapy
Susceptible (S)Intermediate (I)Resistant (R)
Ciprofloxacin >=8 R
Clindamycin >=8 R
Erythromycin >=8 R
Gentamycin <=5 S
Levofloxacin >=8 R
Linezolid 2 S
Oxacillin >=4 R
Penicillin G >=0.5 R
Rifampin <=0.5 S
Tetracycline <=1 S
Tigecycline <=0.12 S
Sulfa/Tri <=10 S
Vancomycin <=0.5 S
Staphylococcus aureus
Spectrum of Coverage…Gram positive coverage:Penicillins (ampicillin, amoxicillin) penicillinase resistant (Dicloxacillin, Oxacillin)*Cephalosporins (1st and 2nd generation)*Macrolides (Erythromycin, Clarithromycin, Azithromycin)*Quinolones (gatifloxacin, moxifloxacin, and less so levofloxacin)*Vancomycin* (MRSA)Sulfonamide/trimethoprim*(Increasing resistance limits use, very inexpensive)Clindamycin*TetracyclinesChloramphenicol (causes aplastic anemia so rarely used)Other: Linezolid, Synercid (VRE)
Gram negative coverage:Broad spectrum penicillins (Ticarcillin-clavulanate, piperacillin-tazobactam)*Cephalosporins (2nd, 3rd, and 4th generation)*Aminoglycosides (Gentamicin; nephrotoxic)*Macrolides (Azithromycin)*Quinolones (Ciprofloxacin)*Monobactams (Azetreonam)*Sulfonamide/trimethoprim*Carbapenems (Imipenem)ChloramphenicolPseudomonas coverage:Ciprofloxacin*Aminoglycosides*Some 3rd generation cephalosporins4th generation cephalosporinsBroad spectrum penicillins*Carbapenem
Spectrum of Coverage…Atypical coverage:Macrolides (Legionella, Mycoplasma, chlamydiae)*Tetracyclines (rickettsiae, chlamydiae)*Quinolones (Legionella, Mycoplasma, Chlamydia)*Chloramphenicol (rickettsiae, chlamydiae, mycoplasma)Ampicillin (Listeria)
Anaerobic coverage:Metronidazole*Clindamycin*Broad spectrum penicillins*Quinolones (Gatifloxacin, Moxifloxacin)CarbapenemsChloramphenicol
Antifungal spectrum of activity against common fungi.
Ashley E S D et al. Clin Infect Dis. 2006;43:S28-S39© 2006 by the Infectious Diseases Society of America
Factors that affect outcome in AST…Prompt institution of treatment“Bug Factor” – virulence and susceptibility“Drug Factor” – Activity of site of infection“Host Factor” – co-morbids and immunocompetence“Site Factor” – easily accessible site by antimicrobialsProblems with administration – timeliness, storage, deterioration, patient compliance, absorption failureRenal/Liver Failure
40
Specimen Collection: Garbage In = Garbage Out!
Specimen quality is keyNeed to reduce colonizing bacteria prior to specimen collection – If you can touch the site with your finger, the specimen will be contaminated!Refrigerate/keep cold when necessaryUse preservatives when applicableTissues/Body fluids, Anaerobic cultures, CSF – stat specimensLabel all specimens at the bedside/where collected with 2 patient identifiers and pertinent specimen information (D/T coll, source/site, abx, who coll)
Cerebrospinal Fluid InterpretationCSF should be clear & colorlessGlucose 40-70 mg/dlProtein 15-45 mg/dlCSF Glucose = ~2/3 serum glucoseBacterial Meningitis:
1. WBC = increased2. Diff – neutrophils3. Protein = marked
increase4. Glucose =markedly
decreased
Viral (Aseptic) Meningitis:1. WBC = increased2. Diff – lymphs3. Protein = moderate
increase4. Glucose = Normal
TB/Fungal Meningitis:1. WBC = increased2. Diff – Lymphs and Monos3. Protein = moderate to
marked increase4. Glucose = Normal to
decreased
Knowledge Check…
The validity of a culture report is dependent on the quality of the specimen sent. To determine if an expectorated sputum specimen is sputum and not saliva, the gram stain should show:
a. < 10 epithelial cells per low power field (lpf)b. > 10 epithelial cells/lpf and moderate polysc. > 10 epithelial cells/lpf and many Pseudomonas
in cultured. Many WBCs and organisms on low power field
Knowledge Check…
To increase recovery of AFB from expectorated or induced sputum, specimens should be collected:
a. Once a week for 3 consecutive weeksb. Every day for 1 weekc. First morning specimen for 3 consecutive daysd. Three specimens 1 hour apart on the same day
Knowledge Check…Microorganisms are grown on culture media made of an agar base. Additives to media vary according to growth requirements of organisms and/or the desire to select out a specific organism. Fastidious organisms require______ media, and ______ media is used to inhibit normal commensals.
1. Differential2. Enrichment3. Selective4. Nutrient broth5. Synthetic sheep blood agar
a. 1, 3 c. 3, 4b. 2, 3 d. 5, 1
Knowledge Check…
Gram stains classify an organism as gram-positive or gram-negative. The determinant factors for Gram stains are cell wall component of:
a. Peptidoglycansb. Lipidsc. Polysaccharidesd. Mycolic acids
Knowledge Check…A liquid stool specimen is collected from a 10 yo boy at 9 p.m. The physician has ordered a culture and O&P. The specimen is refrigerated until 9 a.m. the following day, when the physician calls and requests the laboratory to look for amoebic trophozoites. The best course of action is:
a. Request a fresh specimen.b. Perform a concentration on the specimen.c. Perform a trichrome stain on the specimen.d. Perform a saline wet mount on the specimen.
Knowledge Check…When reviewing microbiology data looking for isolates of MRSA, the laboratory does not use methicillin for testing. Which of the following antimicrobial agents is the MOST similar to methicillin and is most commonly used in AST?
a. Carbenicillinb. Oxacillinc. Gentamicind. Amikacin
Knowledge Check…An IP is asked to review with a group of staff nurses how to interpret ASTs. The susceptibility test that allows a determination of the least amount of antibiotic per milliliter that impedes the growth of an organism is know as a:
a. Minimum inhibitory concentration (MIC)b. Kirby-Bauer disk diffusionc. Minimum bacteriocidal concentrationd. Serum-cidal levels
Microbiological Environmental Sampling
Not recommendedCostlyRequires special proceduresNo standards for comparisonMay have adverse intervention implementedWhen investigation suggests a source or reservoirUse quantitative methods
Routine monitoringBiological monitoring of sterilization processesMonth culture colony counts and endotoxin testing of water and dialysate in HDUsShort term evaluations of interventions implemented as anew process or to stop an outbreak
50
Microbial PathogenesisNormal Flora – commonly found on healthy human body surfaces (endogenous source)Colonization – microorganisms in the absence of symptoms or deep tissue invasionAsymptomatic Infection – viable organisms without causing any obvious symptoms (latent TB)Opportunistic Infections – cause disease primarily in immunodeficient hostsPathogenic Organisms – causes tissue damageInfection – invasion by and multiplication of organisms causing tissue damage and disease
Epidemiologically Significant Pathogens
Etiology (Organism)Pathogenesis (Life cycle understanding)Identification (S/S)Diagnostic TestingIncubation PeriodTransmission-based PrecautionsTreatmentCase Fatality
Selected Infectious DiseasesAnthrax (Class A)Aspergillosis: environmentalChicken pox/Herpes zosterConjunctivitisCryptosporidiosisDengue – Flaviviruses 1, 2, 3, 4Foodborne DiseasesHanta virusHepatitis – A, B, C, D, EHIVInfluenza LegionellosisMeaslesMeningitis – bacterial vs viral
MumpsPediculosis/Phthiriasis – licePertussis – Bordatella pertussisPlague (Class A) – Y. pestisRabiesRSV (pediatric/geriatric)RubellaSARSScabies – Sarcoptes scabeiTB – M. tuberculosisTyphoid Fever (Salmonella typhi)Typhus Fever - RickettsiaWest Nile VirusYellow Fever - Flavivirus
Knowledge Check…A 27 yo man is admitted with symptoms suggestive of meningitis. The patient has a history of head trauma from MVA. The lab calls to report that a g+c is noted on the gram stain. What is your next action?
a. Have the charge nurse compile a list of exposed staff.b. Notify EH that several employees will need
prophylaxisc. Tell the staff that no one should be treated until the
culture report is finald. Ensure that staff understand which organisms are
treated and which are not.
Knowledge Check…
A gram negative bacterium responsible for chronic antral disease and a major factor in peptic ulcer disease is:
a. H. pyogenesb. S. typhic. C. difficiled. H. pylori
Knowledge Check…
An example of an obligate intracellular parasitic bacterium would an organism responsible for:
1. Hepatitis a. 2, 32. Q Fever b. 2, 43. Malaria c. 3, 44. Epidemic typhus d. 1, 2
Knowledge Check…You are notified by the lab that 3 patients on the oncology ward have cultures (2-BAL, 1-sinus) positive for Aspergillus fumigatus and chart review indicates invasive disease. All 3 cultures were taken on the same day. Your FIRST course of action is:
1. Notify the head nurse and medical director of the unit.2. Set up a meeting with engineering to discuss the air
handling system.3. Ask micro to do a retrospective review of Aspergillus
cultures.4. Notify administration of the outbreak.
a. 1, 3 b. 1, 2 c. 3, 4 d. 1, 4
Knowledge Check…Review of micro logs revealed 4 more +Aspergillus cultures in the last 6 months. Chart review indicate the patients were from different units and were community-associated colonization. Based on this, you:
a. Decide no follow-up is necessary since oncology patients are high-risk for Aspergillus.
b. Look for a common factor in all 7 patients.c. Look for a common factor among the 3 oncology
patients only.d. Continue investigating all 7 patients via phone
interview.
Knowledge Check…While touring the oncology unit and outside perimeter of the hospital, you observe road construction one block form the hospital. (The oncology is a street level, facing the construction.) You decide this could be the source of the Aspergillus. Possible factors include:
1. Staff props the outside doors open when they go outside.2. Pigeons roost on the unit’s windowsill.3. The air intake system on the roof faces the construction.4. The unit’s utility room has an open window.
a. 1, 3 c. 1, 4b. 2, 4 d. None, construction is too
far away.
Knowledge Check…A meeting was called with the head nurse, medical director, and vice president of engineering. Proposed interventions included adding an alarm to sound when the outside door was open longer than 30 sec., placing a positive airflow vent over the door way, and locking the utility room window. To determine whether these measures were effective, you will:
1. Monitor every patient on the unit for the next 6 mo.2. Have the micro lab notify you immediately in the
event of another + culture.3. Tour the unit daily to ensure the engineering controls
are in place.4. Consider the problem solved and move on. 60
Knowledge Check…
A patient has a perirectal swab positive for VRE. This is an example of:
a. Normal florab. Colonizationc. Asymptomatic infectiond. Symptomatic infection
Knowledge Check…
Of the following viruses, which is the most common healthcare-associated pathogen in pediatric wards?
a. Respiratory syncytial virus (RSV)b. Adenovirusc. Herpes simplex virusd. Cytomegalovirus
Knowledge Check…
A 10 - yo boy is admitted to the hospital with a 3 day history of fever, abdominal pain, diarrhea, and vomiting. He and his family have just returned from a week long camping trip in the mountains that included trips to the seashore.
The next 4 questions refer to this scenario.
A stool culture is reported with many lactose negative colonies. The most probable causing organism is:
a. Providencia alcalificiensb. Providencia stuartiic. Yersinia enterocoliticad. Providencia rettgeri
Which of the following organisms can grow in the small bowel and cause diarrhea in children and traveler’s diarrhea through the production of enterotoxins?
a. Yersinia enterocoliticab. Escherichia colic. Salmonella typhid. Shigella dysenteriae
Which disease requires a very small inoculum of organisms to cause disease?
a. Dysentery (Shigella)b. Salmonellac. Campylobacterd. Giardia
Which organism found in food poisoning causes the most rapid onset of symptoms?
a. Salmonella enteritidisb. Shigella sonneic. Staphylococcus aureusd. Escherichia coli
Knowledge Check…A 14 uo boy form rural Maryland was seen in the ED with fever, fatigue, chills, headache and a large annular lesion on his left thigh which the patient described as burning and itching. What is the most probable vector of this child’s illness?
a. Tickb. Mosquitoc. Flead. Louse
Knowledge Check…
You receive a call from a young man who thinks he was exposed to HIV. His baseline HIV test (ELISA) was negative. At what time period after the exposure would we be most likely to detect HIV antibodies?
a. 6 months b. 1-3 months c. 12 months d. 3 weeks
Knowledge Check…
A preadmission serum sample and a current sample from a patient is used for antibody testing for HSV. ELISA is performed on paired sera with the following titers: previous = 1:8, current = 1:128. The results indicate:
a. Acute HSV infectionb. Indeterminate infectionc. Chronic infectiond. Immunity to HSV
70
Knowledge Check…
A single serum sample is sent for ELISA antibody testing. The following titers are reported: HSV titer = 1:128, CMV = <1:8, EBV = <1:8. These results indicate:
a. Immunity the HSVb. Confirmation of acute HSV infectionc. Presumptive identification of HSV infectiond. Immunity to CMS and EBV
Knowledge Check…An emaciated homeless person is admitted with suspicion of TB. He had an upper lobe cavitary lesion and a +PPD of 10 mm. He is placed in Airborne precautions in negative pressure. The lab indicates 3 +AFB smears. This indicates:
a. Confirmed diagnosis of TBb. Presumptive mycobacterial infectionc. Presumptive diagnosis of TBd. No conclusion is possible from this information.
Thank you!
Recommended