Application of microbiological assay to determine the potency of intravenous antibiotics

Demonstration of equivalent amounts of active pharmaceutical ingredient is a basic requirement for intravenous generic drugs prior to administration. Physicochemical methods are often used to determine concentration of antibiotics in biological fluids. However, it does not permit direct quantification of potency of a desired antibiotic. This study demonstrates the application of a microbiological assay to determine the potency and concentration of commercially available pharmaceutical-grade antibiotics used for injections. Concentration-dependent variation of inhibitory effect of four commercial brands of cefuroxime and two of ciprofloxacin were observed against two reference bacteria (Escherichia coli DH5α and Escherichia coli ATCC 8739) on Mueller Hinton agar. Regression analysis was used to assess the in vitro equivalence of generic products sold by different retail companies in Dhaka city. A linear relationship was found between the concentration and response of the bacteria in regression analysis where anti-log of X-intercept and slope showed the concentration and potency, respectively. The study showed excellent results of linearity (r2≥0.89), precision (inter assay variation ≤10% for cefuroxime and ≤20% for ciprofloxacin), accuracy and specificity tests for both types of antibiotics. Pharmaceutical equivalence demonstrated by four cefuroxime and two ciprofloxacin samples showed no significantly distinguishable slopes (P > 0.78 and P > 0.44) and intercepts (P > 0.25 and P > 0.07), respectively. Estimated potency for cefuroxime was 91.1-100.0% and for ciprofloxacin was 68.1-100.0%. Microbiological assay was found to be convenient, rapid, cost-effective, precise and accurate in demonstrating pharmaceutical equivalence of antibiotics in different dosage forms. This technique can be used as an alternative method for testing generic antibiotics prior to their use in animal and human. Stamford Journal of Microbiology, Vol.10 (1) 2020: 25-29

No-Touch Automated Disinfection System for Decontamination of Surfaces in Hospitals

Background: Hospital-acquired infections (HAIs) remain a common problem, which suggests that standard decontamination procedures are insufficient. Thus, new methods of decontamination are needed in hospitals. Methods: We assessed the effectiveness of a no-touch automated disinfection (NTD) system in the decontamination of 50 surfaces in 10 hospital rooms. Contamination of surfaces was assessed with a microbiological assay and an ATP bioluminescence assay. Unacceptable contamination was defined as > 100 colony forming units/100 cm2 in the microbiological assay, and as ≥ 250 relative light units in the ATP assay. Results: When measured with the microbiological assay, 11 of 50 surfaces had unacceptable contamination before NTD, and none of the surfaces had unacceptable contamination after NTD (p < 0.001). On the ATP bioluminescence assay, NTD decreased the number of surfaces with unacceptable contamination from 28 to 13, but this effect was non-significant (p = 0.176). On the microbiological assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 11-fold (lamp holder, 1150 CFU/100 cm2). On the ATP bioluminescence assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 43-fold (Ambu bag, 10,874 RLU). Conclusion: NTD effectively reduced microbiological contamination in all hospital rooms. However, when measured with the ATP bioluminescence assay, the reduction of contamination was not significant.