Phenotypic Detection of Extended-Spectrum β-lactamases (ESBLs) and Aminopenicillin Cephalosporinase (AmpC)-Producing Bacterial Isolates from Surfaces of Hospital Fomites and Hands of Healthcare Workers

The hospital environment can significantly contribute to the spreading of bacterial isolates that pose a risk to public health. In this study, we analyzed bacteria found on hospital fomites and the hands of healthcare workers to determine the presence of resistant enzymes such as ESBLs and AmpC.

We studied 100 samples collected from hospital fomites - including the hands of healthcare workers - for bacterial growth, which were subsequently identified using standard procedures. Standard disk methods were used to screen Gram-negative bacteria (GNB) for ESBL and AmpC production, including presumptive and confirmatory testing.

46 (46.0%) Gram-negative bacteria were isolated from all sampling sites, including a preponderance of Pseudomonas aeruginosa and Escherichia coli. Of the 46 GNBs, 31 (67.4%) and 27 (58.7%) were resistant to ceftazidime and ceftriaxone, respectively. The double disk synergy test (DDST) showed ESBL in 34 (73.1%) of the isolates, with the highest prevalence in E. coli (32.3%) and P. aeruginosa (26.5%). These isolates were primarily associated with patients’ bedding (32.4%), tablets (26.5%), and sinks (20.6%), although there was no statistical difference (P=0.998). Presumptive AmpC production was 100% in isolates of K. pneumoniae, C. diversus, Shigella spp., and S. marcescens but variable in other isolates. The combined disk test (CDT) showed that 29 (63.0%) isolates were AmpC-producing GNB, with the highest prevalence in E. coli (34.5%).

The isolation of bacteria with these types of resistance from the surfaces of hospital fomites may negatively impact the quality of healthcare delivery.