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Journal of the Academy of Hospital Administration

An Epidemiological Study of Biohazards in Microbiology Laboratory at Large Teaching Hospital

Author(s): U B Misra *, A K Agarwal **, N K Parmar ***, R Bhalwar ****

Vol. 12, No. 2 (2001-07 - 2001-12)

Abstract: The workers of microbiology laboratories are constantly exposed to pathogenic or potentially pathogenic organism. The magnitude of this problem has been explored by various authors in the past. Majority of the studies / surveys were conducted to find out the degree and type of diseases due to hazardous exposure in the laboratories. However, it is equally important to find out the epidemiological distribution of hazardous exposures during collecting, processing, and carrying out the disposal of the specimen. With this aim, the present study was undertaken at microbiological laboratories of two large teaching hospitals in Pune. With the help of the pilot study and initial exploration, a sample size of 73 laboratory workers was determined which was further enhanced to 100 to increase the precision of the study. The data was collected with the help of questionnaire and observation based studies. The study revealed that 50% of the workers used incorrect method of specimen collection. In 16.2% cases material remained on out side surface of the container with a possible source of Laboratory Acquired Infection. In 63.2% cases none of the centrifuging tube was covered with cap, adding to a possible source of inhalation biohazards. In case of 3.6% to 28.9% workers the disposal method of used equipment was incorrect. Further in case of 32.5% to 42.5% cases the method of disposal of unused specimen was partially correct and was incorrect in case of 5% to 7% laboratory workers. Finally 2% of the workers were found carrying out mouth pipefitting. The study illustrates that all above factors must be incorporated in standard laboratory practice and it should also be part of the raining curriculum of laboratory workers.


Laboratory personnel, particularly those working in microbiological laboratories are quite prone to biohazards which may result into laboratory Acquired Infections. Our knowledge regarding Laboratory Acquired infections may be far from complete because there has been no universal requirement for reporting of such infections.

To find out the magnitude of the problem of Laboratory Acquired infections, various authors have conducted a series of surveys in the past from time to time. The most extensive and historically most important survey was conducted by Sulkin and Pike1 in 1951. The data collected by various authors suggested that working with pathogenic micro-organism places a person at a definite risk of infection. The rapid technological development of Armed Forces Medical Sciences has resulted in the upgradation of microbiological laboratories, with increased exposure of laboratory personnel to hazardous and infectious waste. However, there has been hardly any scientific study in Armed Forces in this field.

The present study was undertaken to assess the problem of biohazards during collection of specimen, processing the same and carrying out waste disposal from the microbiological laboratories of two large teaching hospitals so that necessary preventive measures could be taken before hand.

Material and Methods

It was a cross-sectional, observation design, undertaken in the settings of microbiology laboratories of two large teaching institutions in Pune. Initial exploration and pilot study conducted by the worker indicated that the proportion of personnel having a possible biohazard explore was likely to be around 25% (p = 0.25). the two tailed alpha (type 1) error was kept at conventional levels of 0.05, with a view to estimate the real parameter within 10% deviation of the truth i.e., between 15 to 35%, the estimated truth being approximately 25% as stated earlier, the sample size was worked out to be 73. Since the total study population including both the institutions was around 100, which was more than the minimum sample size of 73, a consecutive sample of total study population was taken2.

The data collection was done with the help of a schedule including 2 parts. The first part contained questionnaire for obtaining information from individual worker on technique of obtaining specimen, processing the same and disposal of waste from microbiological laboratories. The questionnaire was developed on the basis of available standard texts3,4,5. The second part was used to record observations on above mentioned subjects. The date on questionnaire was recorded by using a personal interview technique. Adequate steps were taken to reduce/ prevent respondent's bias, information bias and misclassification bias. The observations on the workers were made by a discreet method so that laboratory workers do not become of the same, to avoid "Hawthorne Effect Bias"6. The criteria for obtaining the specimen, processing and waste disposal were based on standard guidelines3,7,8,9.


Technique of obtaining microbiological specimen:

The hazardous exposures associated with technique of obtaining microbiological specimen are presented in Table-1. It is observed from Table 1 that majority of the workers were not taking blood samples in the laboratories. Amongst those who had collected specimen (Serial 2) 50% used correct method and other 50% used incorrect method. It was because they removed the needles and recapped them contrary to the recommendations made by WHO6. It was also observed from the above Table (Serial 3) that in 97.3% cases containers used were leak proof. In 16.2% cases (Serial 4), material remained on outside surface of the container with a possible source of laboratory infection6.

Table 1: Technique of obtaining microbiological specimen

Sr. No. Heading Number of Workers Percentage
1. Blood Sample is obtained by   NA=89; N=11
  Sterilized sets 9 81.80
  Not sure 2 18.20
2. Methods of drawing blood samples    
  Correct 2 50
  Incorrect 2 50
3. Were containers used leak proof   NA=25; N=75
  Yes 73 97.30
  No 2 02.70
4. Did any material remained out after the cap was closed   NA=32; N=68
  Yes 11 16.20
  No 57 83.80
Note : NA : Not applicable - The aspect was not applicable to the workers specified as they were not involved in the particular procedure at the time of the taking observations.

Technique of Processing the Specimen:

The answers to questions on possible hazards during processing of specimen are presented in Table 2. It is observed from Table 2 (Serial 1) that only in about 8.8% of cases, all the centrifuge tubes were covered by caps, and in 63.2% cases non was covered. It is also observed from Table 2 (Serial 2) that majority of laboratory workers were either using automatic (18.4%) or rubber teat pipettes (63.3%).

Table 2 Answer on Processing the Specimen

Sr. No. Heading Number of Workers Percentage
1. All the tubes covered while centrifuging   NA=43; N=57
  All covered 5 8.80
  Some are covered 16 28.00
  None is covered 36 63.20
2. Methods of drawing samples in pipette   NA=51; N=49
  By automatic pipette 9 18.40
  By rubber teat pipette 31 63.30
  Both of above 8 16.30
  By mouth pipetting 1 2.00
Note : NA : Not applicable - The aspect was not applicable to the workers specified as they were not involved in the particular procedure at the time of the taking observations.

Observations made on processing the specimen:

The observations made on processing the specimen are presented in Table 3. It is observed from Table 3 (Serial 1) that out of 63 workers who were required to carry out pipetting, only 1 (1.6%) undertook mouth pipetting, while the remaining 62 (98.4%) did not do any mouth pipetting. This finding was based on direct discreet observation.

It is also observed from Table 3 (Serial 2 and 3) that in 3.7% of cases the material came in contact with work place and in even number of cases spilling of specimen was observed.

It is further observed from Table 3 (Serial 4), that 72.9% of workers were careful and 27.1% were not while opening the containers.

Table 3: Observation on processing the specimen

Sr. No. Heading Number of Workers Percentage
1. Did the worker do any mouth pipetting   NA=37; N=63
  Yes 1 1.60
  No 62 98.40
2. Did the material come in contact with work place when the cap was opened and kept down   NA=18;N=82
  Yes 3 3.70
  No 79 96.30
3. Was there any spilling of material any time   NA=18: N=82
  Yes 3 3.70
  No 79 96.30
4. Was the worker careful while opening the container   NA=18; N=82
  Yes 51 72.90
  No 19 27.10
Note : NA : Not applicable - The aspect was not applicable to the workers specified as they were not involved in the particular procedure at the time of the taking observations

Technique of waste disposal:

This included disposal of used equipment and disposal of unused specimen.

Disposal of used equipment:

It is observed from table 4 that the correct method of disposal of various used equipment was being practised by 28.9% (disposal of syringes and needles) to 63.8% workers (used petridishes). The method of disposal was partially correct in case of 31% to 46.9% of workers while in case of 3.6% to 28.9% of workers the method of disposal was incorrect.

Table 4: Disposal of used Equipment

S. No. Method of Disposal Glass Syringes & Needles N = 37 Disposable Syringes & Needles N = 38 Pipette N=64 Petri Dishes N = 58 Tubes Slides Cover Slips N = 84 Gloves Masks & Gowns N = 79
    No(%) No(%) No(%) No(%) No(%) No(%)
1. Correct 18 11 28 37 44 37
    (48.40) (28.90) (43.80) (63.80) (52.40) (49.80)
2. Partially Correct 17 16 2. 30 18 37 34
    (45.40) (42.10) (46.90) (31) (44) (43)
3. Incorrect 3. 02 11> 06 03 03 08 >
    (5.40) (28.90) (9.40) (5.20) (3.60) (10.10)

Disposal of unused specimen:

It is observed from Table 5 that the correct method of disposal of used specimen was being practised from 52.5% workers in respect of stool samples to 60.6% of workers in respect of other body samples. In 32.4% (other body samples ) to 42.5% (stool samples) workers it was partially correct while in case of 5% (stool samples) to 7% (other body samples) workers it was incorrect.

Table 5: Disposal of unused specimen

S.No. Methods of Samples Stool Disposal Other Body Samples
    N=40 NA: 60
N = 71, NA:29
1 Correct 21(52.50) 43.(60.60)
2 Partially Correct 17(42.50) 23(32.40)
3 Incorrect 02(5.00) 05(7.00)
Note : NA : Not applicable - The aspect was not applicable to the workers specified as they were not involved in the particular procedure at the time of the taking observations.


Of the various hazardous activities undertaken in the laboratories, drawing of specimen is possibly the single most important factor. The observation that as many as 50% of the laboratory personnel did not use the correct procedure, indicates an urgent need to step up educational as well as supervisory steps. Similarly, the process of centrifuging gives rise to aerosol formation, and if the tubes are not covered (as noticed in as many as 63.2% i.e., two third cases in this study) the potential for transmission through inhalation of the hazardous material by the worker may be substantial3,7,8. Further, a small proportion of the workers were observed to practice mouth pipetting, a procedures which should be strictly prohibited, as per recommendations of WHO and Her Majesty's Stationary Office3,8. Adequate administrative measures need to be taken to stop this practice.

As regards coming in contact with splashes, the findings of present study indicate that in 3.7% cases, the material came in contact with work place or actual spilling occurred. This figures is less as compared to 26% reported by Pike10, possibly because of the particular settings of large teaching laboratories in the present study. In addition the observation that 27.1% workers were not careful while opening the containers calls for concern on these aspects in the training and educational programme of laboratory workers. Another important aspect which need to be stressed in the educational and supervisory procedures is regarding proper disposal of used equipment and unused specimen, as observed in this study.

Laboratory safety is responsibility of the management as well as the workers. Management must create proper environment by framing the safety policies and procedures while the workers must practice them. Above results indicated that there was an urgent need for incorporating following aspect in the training programme of laboratory workers:

  1. Recapping and mouth pipetting must be forbidden.
  2. While centrifuging, the tubes should be closed by a suitable cap to avoid biohazards due to inhabitation.
  3. There should not be any spillage while opening the container.
  4. The specimen must not come in contact with the work place when the cap of container is opened and kept on the bench.
  5. Policies regarding waste disposal from work bench to primary disposal area of from latter to final disposal are including segregation system for contaminated waste and colour coding.


  1. Sulkin S E and Pike R M Laboratory Acquired Infections, Journal of American Medical Association 1951; 147: 1740-45.
  2. Hulley S B Cumings S R Designing Clinical Research - Epidemiological Approach, First edition, 1988; Williams & Wilkins Baltimore USA, 18-30.
  3. Laboratory Biosafety manual. Second edition, Geneva: WHO, 1993; 1-47, 55-83, 99-119.
  4. Biosafety in Microbiological and Biomedical Laboratories U,.S. Department of Health and Human Services, Public Health Services, Centres for Disease Control and Prevention and National Institute of Health, 3rd Edition, U.S. Government Printing Office Washington, 1993; 6-70.
  5. Barker JH, Blank Ch, Steere NV, Designing A Laboratory. Washington, D C : American Public Health Association, 1983; 59-126.
  6. Weihrich H., Koontz H. Management - A Global Perspective Tenth Edition, McGraw - Hill Inc., New York, 1994; 42.
  7. Collins C H Laboratory - acquired infections. Second edition, London: Butterworths, 1988; 5-33.
  8. Department of Health and Social Security, Scottish Home and Health Department, Department of Health and Social Services Northern Ireland, Welsh Office, Code of Practice for Prevention of Infection in Clinical Laboratories and Post-Mortem Rooms. London: Her Majesty's Stationery Office 1987; 1-16, 19-36.
  9. Recombinant DNA Safety Guidelines and regulations, Department of Biotechnology Ministry of Science and Technology, Government of India, January 1990; 2-9.
  10. Pike R M Laboratory Associated Infections, Summary and Analysis of 3921 cases. Health Laboratory Science 1976; 13: 105-114.

* Joint Director, Medical services (Projects) Directorate General of Medical Services AG's Branch, L Block, Room 111, Army Headquarters, New Delhi - 110001
** Director, School of Health Sciences, Indira Gandhi National Open University, New Delhi - 110068
*** Professor and Head, Department of Hospital Administration, Armed Forces Medical College, Pune
**** Reader and Epidemiologist, Department of Preventive and Social Medicine, Armed Forces Medical College, Pune

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