Prevalence and distribution of ampc beta-lactamase producing and isolates obtained from urine samples at a tertiary care hospital in the caribbean.

Introduction: The aim of this study was to investigate the prevalence and distribution of AmpC beta-lactamases (BLs) in uropathogens ( and ) at the University Hospital of the West Indies Jamaica (UHWI).

Method: De-duplicated consecutive urine samples, collected from January to March 2020 at the UHWI, were analyzed. Screening and phenotypic confirmatory tests were conducted using resistance to cefoxitin and the Disc Approximation Test (DAT) respectively, for isolates of interest. Multiplex PCR was performed on cefoxitin resistant (CR) isolates for the detection of , , , , and genes. Whole genome sequencing (WGS) was used to further detect AmpC BL genes in PCR negative isolates with indeterminate phenotypic results.

Results: Sixty-four Gram negative isolates were obtained from 61 patients (55% female), aged 18 months to 88 years old. At least 35% (26) had complicated urinary tract infections. Only 7 out of 64 isolates were or , had antibiograms suggestive of possible AmpC BL production and were CR. DATs confirmed AmpC BL in two of these (1 K; 1 ), one tested negative () and four had inconclusive results ( PCR detected and in two CR isolates. WGS further detected in one isolate. The prevalence of screened CR isolates with AmpC BL is 57.14% (4 of 7), representing 6.25% of the sample. AmpC BL producers tested had 100% susceptibility to meropenem and nitrofurantoin.

Conclusion: AmpC BL prevalence among and , common urinary pathogens, in the studied isolates is low. Although cefoxitin screening is helpful, phenotypic screening using the DAT can yield indeterminate results best clarified by molecular testing.