Efficacy of disinfectants against multi-drug resistant bacteria isolated from clinical samples at Muhimbili National Hospital, Dar es salaam, Tanzania

Abstract

ABSTRACT Background : Increased multi-drug resistant (MDR) bacterial infections have been associated with increased hospital care costs and mortality due to Health Care Associated Infections (HCAIs). This due fact that, bacteria resistant to disinfectants have also been reported and are on the rise. Disinfectants are prerequisites for infection control and prevention in healthcare settings. Increased bacteria resistant to antimicrobial agents, including disinfectants, warrants ongoing monitoring efficacy of routinely used disinfectants in hospitals settings. However, there is a paucity of information on the efficacy of routinely used disinfectants, especially in developing countries, which reflects the need for conducting this study. O bjective: To evaluate the efficacy of disinfectants against multidrug resistant bacteria isolated from clinical samples at Muhimbili National Hospit al. Materials and Method s : A laboratory based experiment was conducted to assess the efficacy of disinfectants by using dilution test methods and the quantitative suspension test methods. The Quaternary ammonium compound (QACs), povidone iodine, and sodium hypochlorite (NaOCl) at undiluted and ready to use concentration were collected and tested against four clinical isolates from blood sample and two quality control strains: Methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E.coli), carbapenem-resistant Acinetobacter baumannii (CR-A. baumannii), and carbapenemase producer Klebsiella pneumoniae (CPKP), and reference quality control) strains Escherichia coli ATCC 3 5918 and Staphylococcus aureus ATCC 25923 Results All tested bacteria were significantly killed with > 99.999% reduction rate at contact exposure of 10 minutes by all selected disinfectants disinfectants. The 1% QACs killed all tested bacteria at five minutes of exposure, however only gr am positive bacteria were rapid killed after one minute. The 0.5% NaOCl was not efficacious at one minute to all tested bacteria, furthermore at 5 minutes, was significantly only for E. coli ATCC 35918 and CRKP. Exposure of 10% povidone iodine for 1 and 5 minutes did not significantly reduced MRSA and carbapenem-resistant Acinetobacter baumannii. For QACs, the MICs of both ATCC control strains and MDR bacteria were ranged from 3,125 to 6,250 mg/L and produced the same MBCs of 6250 mg/L. The MICs of MRSA and ESBL-Escherichia coli for povidone iodine were twice higher than their reference, and its MBCs was fourfold higher. The MICs of MRSA for NaOCl was four times higher than ATCC-S. aureus 25923 while its MBCs was twice higher. Generally, MDR bacteria shown higher disinfectant tolerance than their corresponding ATCC bacteria strains. By comparison, QACs was highly efficacy than other disinfectants. Conclusions: This study found that, for all tested disinfectants the minimum contact exposure time to bacteria for 10 minutes is required for complete elimination of bacteria. However, the QAC was efficacy at 5 minutes contact time. Therefore, adherence to contact time is critical when disinfection is performed in infection prevention and control.