Personnel working in microbiology laboratories face health risks from exposure to biological hazards. Proper precautions and safety measures must be taken to minimize these risks, including using personal protective equipment like gowns, masks, gloves and eye protection. The laboratory works with bacteria and fungi classified in Hazard Groups 2 and 3, which can cause disease in humans. All personnel, equipment, and procedures must be properly managed to limit the risk of infection through inhalation, skin contact, ingestion or eyes.

2. •Personnel working in a Microbiology
Laboratory directly or indirectly with
biological agents are at risk from exposure to
hazards .
•Adequate precautions/Safety measures to
be taken to avoid biological health hazards.

3. 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 .

4. 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

5. 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

6. • Ingestion- Mouth pipetting, other means by which organisms are conveyed to mouth
include fingers contaminated with spilled cultures, articles like pipes & cigarette & food
directly or indirectly contaminated by fingers .
• Inhalation – Many ordinary lab techniques with microorganisms ( using bacteriological
loops, spreading culture on slides, mixing cultures by bubbling, opening culture tubes which
have wet stopper , opening cultures containing fungal spores and opening lyophilized
cultures 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 settle
rapidly but smaller droplets < 5 um remain suspended in air & are capable to move about a
room/ building by small air currents . These particles if inhaled passes to lungs causing
infection .
•Through Skin(Percutaneous route)- Accidents leading to wounds are responsible for many
kinds of infection . Cuts from broken culture tube or bottle can cause infection .Unbroken
skin on hand contain many microscopic abrasions permitting entry of microorganisms from
surface contaminated due to spillage or settling of large aerosol droplet .
•Through Eye- Microorganisms may enter through the conjunctive in 2 ways
rubbing with contaminated fingers & in splashes of culture fluids .

7. • Equipment- Even with best of techniques poor Equipment will lead to hazard. So to
prevent hazards the instruments should be serviced regularly & calibrated at all times .
• Carelessness – The best equipment will not protect a careless/ untrained personnel from
hazard. So one must be careful while in laboratory and training & supervision must be
provided to the new/ inexperienced personnel .
•Bacteriological Loops- Loops larger than 3mm or are imperfectly closed shed their loads
easily creating infectious aerosols or droplets . So such loops should be discarded
immediately .
•Slide preparation for Microscopy- The cheap slides with sharp edges are easily broken and
may injure fingers with consequent risk of infection .
•Pipe ting- Mouth pipe ting has already been banned to avoid hazards . Mechanical pipe
ting devices and autopipetes are now used which are safe . Violent pipe ting & discharge
must be avoided since both produces bubble which bursts producing aerosols .
•Culture Containers- These should be robust .Thin glass tubes, petriplates, bottles are easily
broken resulting in the dispersal of infectious material & possibly causing personal injury .

8. 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 prevent
infectious hazard .
• Pouring infectious Material- A funnel should be placed over a Discard jar and
its outlet is just below the surface of the disinfectant . The supernatant fluid
now be poured through the funnel . Any drop of liquid remaining in the tube
should be wiped off with tissue paper & discarded in Disinfectant .
• Catalase tests - +ve catalase produce bubbles of oxygen which disperse
aerosols when they burst .so Slide catalase tests should be abandoned in favour
of 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.

9. 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.

10. MINIMIZING INFECTION HAZARDS (Contd.)
Bio-Safety Cabinet- BSC class –II must be installed for the
personnel to use . It provides a physical barrier too to the analyst
performing the work .
Medical Supervision – A staff should me medically supervised
regularly since the personnel deals with pathogens .
Hand Disinfection- it should be done properly by any lab personnel
dealing with pathogens directly or indirectly particularly after
completion of work and before having meal .

11. Responsibility :
Management – Should appoint one or more persons to ensure that
there are no infringements which might lead to litigation or criminal
proceedings. 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 safe
handling of micro-organisms and the protection of other workers. It is
obvious that a microbiological safety officer should acquaint himself
with all microbiological activities and techniques . For example, in a
laboratory where dangerous pathogens are handled, he needs to know
the whereabouts of all cultures and what every Analyst is doing with
them.
Laboratory Personnel- Must co-operate with Safety Staff &
management to prevent Hazard .

12. 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.