Lack of Association Between qacE and qacE∆1 Gene Variants and Sodium Hypochlorite Resistance in Clinical Isolates of ESBL- and Carbapenemase-Producing Klebsiella spp. and Enterobacter spp., from Gaborone, Botswana.

Background

The qacE gene and its variant, qacE∆1, have been associated with resistance to antimicrobials and biocides. This poses a threat to infection prevention, control and treatment. Several studies investigated this relationship with conflicting results. The aim of this research was to determine the prevalence of qacE and qacE∆1 in clinical extended spectrum β-lactamase- (ESBL) and carbapenemase-producing Klebsiella spp. and Enterobacter spp. and elucidate the association of these genes with resistance to sodium hypochlorite.

Methods

This study included 216 isolates of ESBL- and carbapenemase-producing multidrug-resistant (MDR) Klebsiella spp. and Enterobacter spp. These isolates were identified by VITEK-2 analyser. The MIC and MBC of sodium hypochlorite were determined using the microbroth serial-dilution method. PCR was used to detect gene variants. A regression analysis investigated any association between qacE genotypes, MIC and MBC, as well as antimicrobial drug resistance profiles.

Results

Overall, there was a high prevalence of qacE and qacE∆1 variants (84.7%; 95% CI, 79.2-89.2). There was a high prevalence of qacE∆1 (80.6%; 95% CI, 74.6-85.6) as compared to qacE (15.3%, 95% CI, 10.8-20.8). The MIC50 and MIC90 of the isolates ranged between 7031 mg/L and 9375 mg/L and 14,060 mg/L and 18,750 mg/L, respectively, while the MBC ranged from 48,750 mg/L to 18,750 mg/L. There was no association between qacE genotypes and high MIC and MBC as well as antimicrobial drug resistance.

Conclusions

The MIC and MBC of sodium hypochlorite are higher than what is currently used for disinfection in Botswana. There is a high prevalence of qacE and qacE∆1; however, these genes do not seem to be associated with resistance to sodium hypochlorite.