Disinfectants are chemical or physical agents that destroy or remove vegetative forms of harmful microorganisms when applied to the surface. Disinfectants are classified by their types. These include aldehydes, alcohols, halogens, peroxides, quaternary ammonium, and phenolic compounds. Disinfectants vary in their spectrum of activity, mode of action, and efficacy. The first step of an efficient disinfection program is the choice of disinfectants that guarantee bactericidal, fungicidal, and sporicidal actions. The effectiveness of disinfectants can be affected by several factors, including pH, temperature, organic soiling, water hardness, and several dilutions [¹,²].

A disinfection efficacy study is part of a pharmaceutical manufacturing facility’s overall contamination control program. It includes verifying proper cleaning and disinfection procedures and demonstrating that a product possesses antimicrobial activity under defined laboratory test conditions [³,⁴,⁵]. The disinfectants should be tested in several stages, such as preliminary suspension tests to verify whether a product deserves the qualification of a “disinfectant” and tests on surfaces that mimic practical conditions [⁶,⁷].

Disinfectant efficacy studies demonstrate that disinfectants used on surfaces in manufacturing areas effectively inactivate or remove microorganisms, such as bacteria, fungi (yeast and molds), and bacterial spores, and validate the established disinfection procedures that provide the expected level of disinfection [⁸,⁹,¹⁰].

The research was conducted at Quest Pharmaceuticals Pvt., Ltd. from 20/05/2024 to 25/06/2024. It was designed to test the efficacy of disinfectants used in sanitizing areas in the pharmaceutical industry and the use of approved disinfectants during area sanitization procedures in the plant.

Surface challenge tests are widely considered for disinfection efficacy tests. This study is intended to provide an overview of disinfection efficacy testing and highlight its significance within the pharmaceutical industry for controlling contamination within the premise of the pharmaceutical industry. This study aims to find the efficacy of using disinfectants in plants and define the contact time of disinfectants in clean rooms for proper sanitization.

1% Cetrimide shows excellent antimicrobial activity and reduces the tested organisms by 6 logs at an exposure time of 10 minutes, except for E. coli .

2% Lizol shows excellent antimicrobial activity against Pseudomonas aeruginosa and Candida albicans and gives a 6-log reduction at an exposure time of 10 minutes. Still, Bacillus subtilis, E. coli, Salmonella typhi, and Environment Isolate (Bacillus spp) fail to give a 6-log reduction at an exposure time of 10 minutes .

2.5% Dettol shows excellent antimicrobial activity against Bacillus subtilis, E. coli, Salmonella typhi, and Candida albicans and gives a 6-log reduction at an exposure time of 10 minutes. Still, Pseudomonas aeruginosa and Environment Isolate (Bacillus spp) fail to give a 6-log reduction .

CFU, Colony Forming Unit

Disinfectants kill the bacteria by damaging their cell wall or cell membrane at specified Concentration and contact time. The study’s observations were expressed in log10 reductions against different contact times (10 minutes and 20 Minutes). All disinfectants showed good antimicrobial activity and had 5 log reductions or more at a contact time of 10 minutes and 20 Minutes, respectively. The study was conducted on epoxy-coated floors as most of the classified areas in the pharmaceutical industry are epoxy-coated where production activities are done.

Antimicrobial efficacy of 1% Cetrimide showed excellent antimicrobial activity and a 6-log reduction of tested organisms. E coli fails to give a 6log reduction at a contact time of 10 minutes. This might be due to the impact of environmental factors on the organisms under test conditions. 2.5% Dettol also showed excellent antimicrobial efficacy against most tested organisms, but Pseudomonas aeruginosa failed to give a 6log reduction at a contact time of 10 minutes; this might be due to more resistance mechanism of the organism in the tested 2.5% Dettol solution. 2% Lizol showed poor activity against Bacillus subtilis, E. coli, Salmonella typhi, and Environment Isolate (Bacillus spp) and failed to give a 6-log reduction at an exposure time of 10 minutes. This might be due to the organisms’ high resistance to Lizol on low contact time.

The results showed that 1% Cetrimide had excellent antimicrobial activity compared to 2.5% Dettol and 2 % Lizol. This result agrees with Joshi et al. ’s test. [⁶], in which the test disinfectants gave more than a 4-log reduction for the tested organisms. In similar studies by Bhosale et al. [¹¹], the disinfectant activity of tested disinfectants has more than a 5 log reduction. Our findings also agree with a similar study by Kumar et al. [¹²], who stated more than 5 log reduction of test organisms under study. However, the result of Olasehinde et al. [¹³] disagrees with our study, which stated 4 logs or less reduction of the organisms in the study. This could be possibly due to improper dilation or incorrect concentration details mentioned by the manufacturer.

Therefore, this indicates that all the test disinfectants have excellent antimicrobial efficacy at the recommended concentration and contact time of 10 minutes and 20 minutes on test surfaces. Using all the mentioned disinfectants may reduce the contamination caused by the test microorganisms and is an important means of controlling contamination in the disinfectant control program in the pharmaceutical industry.

Several limitations should be acknowledged in this study. First, negative, positive, and sterility controls were not incorporated into the experimental design. This decision was made because the study aimed to evaluate antimicrobial efficacy under practical field conditions with naturally occurring microbial loads on surfaces rather than standardized laboratory conditions with defined inoculation. Second, the statistical analysis is limited due to the study’s primary objective of determining whether the tested disinfectants achieve a 6-log reduction in microbial populations. While log reduction values are reported, the experimental design was not optimized for comprehensive statistical evaluation of treatment differences. However, this approach aligns with industry standards for disinfectant efficacy testing. Third, the differential susceptibility observed between E. coli and Pseudomonas aeruginosa to 1% Cetrimide warrants consideration. Under the tested conditions, E. coli demonstrated reduced susceptibility compared to P. aeruginosa, which may be attributed to species-specific differences in cell wall composition, efflux mechanisms, or environmental stress responses. This finding is consistent with known variations in antimicrobial resistance patterns among gram-negative bacteria and does not compromise the overall validity of the results.

The study shows that the In-use disinfectants are effective at contact times of 10 and 20 minutes, respectively. If the desired log reduction is 6 log reduction during a contamination control program in the Pharmaceutical Industry, then a contact time of 20 minutes should be determined for each disinfectant.1% Cetrimide has excellent antimicrobial activity compared to 2.5% Dettol and 2% Lizol.

Our study concluded that all three disinfectants had broad activity against the organism. Proper concentration and contact period are crucial for any disinfectant to give an excellent result. So, proper concentration and contact time should be determined under practical conditions to get better results when selecting disinfectants for contamination control programs in the pharmaceutical industry.