Query No: 1501 – Newer OT sterilization techniques.


Please give your valuable opinion regarding sterilization methods in OT.  Now-a-days, so many companies are coming with fast ,methods of OT sterilization (within 1-2 hrs) with the help of Silver nitrate solution/ Ammonium chloride solution and a fogger in place of Formalin with Fumigation.  Is it really effective for disinfection?  Please share your experience.
Dr Mahesh Agrawal
Indore, MP.   



Dear Dr. Mahesh,
For sterilization of the OT, in my opinion. the best is formaldehyde vapor because no organism so far has been noted to be resistant to it. There is a lot of literature produced about other fogging method and certain companies proclaim that formalin is carcinogenic Formaldehyde is banned in western countries. But in the era of" Manipulated marketing",  we cannot rely on studies. Formalin vapor fogging is very cheap and effective method, the only demerit is of irritation of nasal mucous membrane and eye burning. For instruments sterilization vertical high pressure autoclaving method is the best to kill the even spore bearing bacteria. The scientific concept behind autoclaving is to achieve more than 100 degree Celsius temperature by achieving more atmospheric pressure. Fast autoclaving is also effective as we can achieve more effective high temperature by raising the pressure speedily. To check the effectiveness of autoclave we have the stickers available from J&J,3M,Proper, Vapolen etc. completion of sterilization can be confirmed by looking at the color changes.

Dr. Hiren Thanki


Dear Dr Mahesh,
I subscribe to views expressed by Dr Thenki. In addition I would suggest everybody whosoever enters OT ( including patients) should dip their hands in a bowl of antiseptic solution ,as it has been found that highest bacterial count in human body is at the fingertips. I have been following last > 20 yrs with good results.

Dr. Mohan Nadiger

Expert Comment:

Dear Dr Mahesh Agarwal,
In most of the developing world, Formalin (40% formaldehyde) is still widely used for operation theatre for fumigation. Though cheap and easily available this product has various drawbacks like
1.  Highly toxic
2.  Irritant to eyes
3.  Carcinogenic
4.  Requires 24-48 hrs of contact period
5.  Poor efficacy against spores
6.  Corrodes sensitive OT equipment
The Silver nitrate based product we have used is Silvicide (0.1% silver nitrate with 10% hydrogen peroxide). The product is claimed to be efficacious in up to 1:20 dilution and a contact period of 45 min for most of the microbes barring more resistant ones like Mycobacterium tuberculosis and HBV. It was discontinued as it is severely irritant to eyes on exposure and both short and long term toxicological profile were still undetermined.
Due to the problems stated above, alternative fumigation and disinfection solutions replacing the older methods. The solutions that we have used till date and found effective are:-
1.  Incidur
Is a formaldehyde free disinfectant with the cleansing activator for surfaces and fumigation of high risk areas and general areas with different concentrations for dilutions which is very economical due to low concentration i.e. 1 % dilution, no eye irritation and non - corrosive. Moreover it takes only an hour to disinfect which helps in emergencies and between two patients. (ACTIVE INGREDIENTS: - GLUTARALDEHYDE AND GLYOXAL
2.  Bacillocid Rasant
Active ingredients: Glutaral 100 mg/g, benzyl-C12-18-alkyldimethyl ammonium chlorides 60 mg/g, didecyl-dimethylammonium chloride 60 mg/g. Microbiological activities
Bactericidal, yeasticidal, tuberculocidal, virucidal against enveloped viruses (incl. HBV, HIV, HCV), virucidal, adeno-, polyoma- and rotavirus.
Areas of application
Bacillocid® rasant is suitable for the disinfectant cleaning of washable surfaces using the wet-wipe-procedure. It is especially suitable for economic short-term disinfection in risk areas that are likely sources of infection. Recommended contact period of 45 min to disinfect between 2 cases.
1.  Microshield D-125
Broad spectrum disinfectant, hospital disinfectant, antimicrobial, broad
Spectrum cleaner & disinfectant, cleans as it disinfects, antibacterial, bactericide,
pseudomonacidal, HIV, & HbV & HcV virucide*,cleaner, disinfectant, sanitizer, detergent, fungicide and deodorizer.
Active ingredients:
Alkyl dimethyl benzyl ammonium chloride ………. 2.37%
Alkyl dimethyl ethyl benzyl ammonium chloride …..2.37%
Recommended dilutions for mopping and fogging are:-
2 ounces per one gallon (or equivalent use dilution of 1:64). This product was proven to be effective against Hepatitis B Virus with a contact time of 10 minutes.
With proper use of all the above solutions the culture samples lifted from various surfaces in OT shows “NO GROWTH” after 48 hours. However the air samplings have not given us desirable results and have come positive for both fungal and bacterial growth. We have therefore installed UV activated air filters (Great White Aerocide) to improve the air quality. It has effectively dealt with the suspended bacterial and fungal load in the air. These are not UV filters as active UV is harmful to personnel in the OT. UV activators come in sealed UV containers which do not cause UV leakage and so run for 24 hours

Dr Sanjay Chaudhary
New Delhi. 


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