Phenotypic and genetic extended spectrum beta lactamase profiles of bacterial isolates from ICU in tertiary level hospital in Kenya

Abstract

Background: Bacterial infections in the ICUs are a threat to the lives of critically ill patients.   Moreover, their vulnerable immunity predisposes them to developing bacteria-associated sepsis, further deteriorating their already fragile health. In the face of increasing drug resistance menace, the problem of bacterial infection in ICU is likely to worsen. This study sought to assess bacterial infections in ICU setting by identifying prevalent gram-negative bacterial species and characterizing their antibiotic susceptibility patterns. Phenotypic and genetic resistance were determined among gram-negative isolates from ICU patients. Methods: Cross-sectional samples collected from Kenyatta National Hospital ICU between    January and June 2021 were cultured for subsequent analysis. Phenotypic identification of culture-positive samples was performed using VITEK 2 while Antibiotic susceptibility patterns were determined based on Antimicrobial Susceptibility Testing (AST) results. Cephalosporin-resistant gram-negative bacteria were assessed by PCR to detect the presence of ESBL genes. Results and discussion: Out of the 168 gram-negative isolates, Acinetobacter baumanii was the most abundant (35%). Other isolates that were present at frequencies more than 15% are Klebsiella pneumoniae and Escherichia. coli. A. baumaniii is known to be a notorious bacterium in ICU due to its multidrug resistance nature. Indeed, A. baumanii isolates from Kenyatta National Hospital showed significantly high level of phenotypic resistance. Concordant with the high level of phenotypic resistance, we found high carriage of the ESBL genes among the isolates analysed in this study.  Moreover, majority of isolates harboured all the four ESBL genes. Conclusion: A high rate of phenotypic and genetic resistance was detected among the tested isolates. Resistance to cephalosporins was primarily driven by acquisition of the ESBL genes. The high-rate multidrug resistance in ICU bacterial isolates in this study has a crucial implication for ICU patient management and general antibiotics use.