Detection of microorganisms on formalin-fixed and stored pathology tissues: A microbiological study
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Gayathri Ramesh1, Anuradha Katiyar1, Ramamurthy Sujatha2
1Department of Oral and Maxillofacial Pathology, Rama Dental College Hospital and Research Centre, Kanpur, Uttar Pradesh, India.
Background:
Formalin is widely used to fix histological preparations and as preservatives in embalming solutions and is an age-long practice in medical laboratories. It is generally accepted that the risk of contracting infections is relatively high among medical laboratory workers and pathologists. Recent studies have, however, suggested that formalin does not effectively inactivate all kinds of microbes in formalin-fixed tissue (FFT). Long time preserved tissues in formalin may develop growth of microbes on the surface of the formalin.
Aims And Objectives:
The purpose of the study is to determine the growth of microorganisms on the surface of FFTs.
Materials And Methods:
Fifty-one containers of 10% formalin with fixed tissues and undiscarded formalin solution not containing tissues of years 2013-2015 (17 in each year) were selected, and samples for inoculation onto the cysteine lactose electrolyte deficient agar plates were taken from the surface of the FFT using sterile cotton tips. The growth of the colonies was checked for after 48 h.
Results:
Out of 51 samples from 2013 to 2015, 17 had shown growth of microbial colonies. Six out of 17 samples of 2013, 7 out of 17 of 2014 and 4 out of 17 samples of 2015 had colonies of microbes on agar plates. Gram-negative bacilli, Bacillus subtilis and micrococci were mostly found.
Conclusion:
There were viable microbes on the surfaces of formalin solution containing pathology tissue. Since cross-contamination by microbes may occur during regrossing or processing, protocols to decrease cross-contamination should be instituted.
Insights
Microbial growth was found on formalin-fixed tissues, posing a risk to laboratory workers. Implementing protocols to reduce cross-contamination is recommended to enhance laboratory safety.
Area of Science:
- Microbiology
- Histopathology
- Laboratory Safety
Background:
- Formalin is a common fixative and preservative in medical laboratories.
- Medical laboratory workers face high infection risks.
- Formalin may not fully inactivate all microbes in formalin-fixed tissues (FFT).
Purpose of the Study:
- To investigate the presence and growth of microorganisms on the surface of formalin-fixed tissues.
Main Methods:
- Fifty-one formalin-fixed tissue samples from 2013-2015 were analyzed.
- Samples were swabbed from the surface of FFTs using sterile cotton tips.
- Inoculation onto agar plates and incubation for 48 hours assessed microbial growth.
Main Results:
- Microbial growth was detected on 17 out of 51 analyzed samples.
- Specific microbes identified included Gram-negative bacilli, Bacillus subtilis, and micrococci.
- Growth rates varied across the years sampled (2013-2015).
Conclusions:
- Viable microorganisms were present on the surfaces of formalin solutions containing pathology tissues.
- Cross-contamination risks exist during tissue regrossing and processing.
- Protocols to minimize microbial cross-contamination are essential for laboratory safety.
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