•Personnel working in a MicrobiologyLaboratory directly or indirectly withbiological agents are at risk from exposure tohazards .

•Adequate precautions/Safety measures tobe taken to avoid biological health hazards.

1. Group 1 – Unlikely to cause human disease

2. Group 2- cause disease, Hazardous to employees

3. Group 3- Cause severe disease & might spread to community

4. Group 4- Severely Hazardous causing disease with no treatment available.

Note : Microbiology dept. of MSK deals with biological agents mostly related to class 2 & 3 .

Organism Biological Agent Hazard Group Notes

Bacteria S. aureus 2 toxigenic

E.coli 2

B.cereus 2

B.subtilis 2 Not in grup appvd

by HSE

S. typhi 2 Vaccine available

S.flexneri 2

P.aeruginosa 2

P. mirabilis 2

K. pneumoniae 2

B.

stearothermophilu

s

Not in grup appvd

by HSE

V.

parahaemolyticus

2

V. cholerae 2

Enterococcus

spp.

2

L. monocytogenes 2

C.perfringens 2

Clostridium spp. 2

R. equi 2

Fungi B. fulva Not in grup appvd

by HSE

Aspergillus spp.

S.cerevisiae

2

Not in grup appvd

by HSE

• Ingestion- Mouth pipetting, other means by which organisms are conveyed to mouthinclude fingers contaminated with spilled cultures, articles like pipes & cigarette & fooddirectly or indirectly contaminated by fingers .

• Inhalation – Many ordinary lab techniques with microorganisms ( using bacteriologicalloops, spreading culture on slides, mixing cultures by bubbling, opening culture tubes whichhave wet stopper , opening cultures containing fungal spores and opening lyophilizedcultures etc) result in the release into the laboratory air of large amounts of aerosol (minute droplets of liquid containing one or few microorganisms ) . Larger droplets settlerapidly but smaller droplets < 5 um remain suspended in air & are capable to move about aroom/ building by small air currents . These particles if inhaled passes to lungs causinginfection .

•Through Skin(Percutaneous route)- Accidents leading to wounds are responsible for manykinds of infection . Cuts from broken culture tube or bottle can cause infection .Unbrokenskin on hand contain many microscopic abrasions permitting entry of microorganisms fromsurface contaminated due to spillage or settling of large aerosol droplet .

•Through Eye- Microorganisms may enter through the conjunctive in 2 waysrubbing with contaminated fingers & in splashes of culture fluids .

• Equipment- Even with best of techniques poor Equipment will lead to hazard. So toprevent hazards the instruments should be serviced regularly & calibrated at all times .

• Carelessness – The best equipment will not protect a careless/ untrained personnel fromhazard. So one must be careful while in laboratory and training & supervision must beprovided to the new/ inexperienced personnel .

•Bacteriological Loops- Loops larger than 3mm or are imperfectly closed shed their loadseasily creating infectious aerosols or droplets . So such loops should be discardedimmediately .

•Slide preparation for Microscopy- The cheap slides with sharp edges are easily broken andmay injure fingers with consequent risk of infection .

•Pipe ting- Mouth pipe ting has already been banned to avoid hazards . Mechanical pipeting devices and autopipetes are now used which are safe . Violent pipe ting & dischargemust be avoided since both produces bubble which bursts producing aerosols .

•Culture Containers- These should be robust .Thin glass tubes, petriplates, bottles are easilybroken resulting in the dispersal of infectious material & possibly causing personal injury .

MINIMIZING INFECTION HAZARDS (Contd.)• Opening Culture Containers- Curators of culture collection usually issue

instructions on how to open ampoules safely & it must be followed to preventinfectious hazard .

• Pouring infectious Material- A funnel should be placed over a Discard jar andits outlet is just below the surface of the disinfectant . The supernatant fluidnow be poured through the funnel . Any drop of liquid remaining in the tubeshould be wiped off with tissue paper & discarded in Disinfectant .

• Catalase tests - +ve catalase produce bubbles of oxygen which disperseaerosols when they burst .so Slide catalase tests should be abandoned in favourof tube catalase tests which contain the aerosols.

Personal Protection- Protective Clothing (gown), Masks, Head cap, Gloves, Shades must be worn while in clean zone to protect normal clothing, Skin, eyes, Nose , Hands etc. from getting infected . If not worn Normal clothes will get contaminated & the infection will spread among employees.

It is important that PPE be:

Selected based upon the hazard to the worker;

Properly fitted

Conscientiously and properly worn;

Regularly maintained

Properly removed , cleaned, disinfected and stored.

MINIMIZING INFECTION HAZARDS (Contd.)

Bio-Safety Cabinet- BSC class –II must be installed for thepersonnel to use . It provides a physical barrier too to the analystperforming the work .

Medical Supervision – A staff should me medically supervisedregularly since the personnel deals with pathogens .

Hand Disinfection- it should be done properly by any lab personneldealing with pathogens directly or indirectly particularly aftercompletion of work and before having meal .

Responsibility :Management – Should appoint one or more persons to ensure that

there are no infringements which might lead to litigation or criminalproceedings. Such individuals would be members of the safety staff.

Safety Staff - one of the most important duties of the safety officer

is the drawing up of local rules and codes of practice for the safehandling of micro-organisms and the protection of other workers. It isobvious that a microbiological safety officer should acquaint himselfwith all microbiological activities and techniques . For example, in alaboratory where dangerous pathogens are handled, he needs to knowthe whereabouts of all cultures and what every Analyst is doing withthem.

Laboratory Personnel- Must co-operate with Safety Staff &

management to prevent Hazard .

CONCLUSIONS

The hazards of working with micro-organisms are real but should not be regarded as alarming. if the risks are appreciated and appropriate techniques are used, casualties are few. The incidence of laboratory-acquired infections may be minimized and they may be almost entirely prevented by good laboratory design, correct equipment properly used, good housekeeping and training in careful technique. The sum of all these may be described as good laboratory practice.