Antimicrobial resistance patterns of Enterobacter cloacae complex and Enterobacter aerogenes strains isolated from clinical specimens: A five-year surveillance study

Introduction: Antimicrobial resistance has become a worldwide problem due to the escalating evolution of resistance combined with a reduced antimicrobial pipeline. The genus Enterobacter is one of the primary pathogens that cause nosocomial infections because of its numerous resistance mechanisms and capacity to "evade" antimicrobial therapy. Aim: The study assessed the antimicrobial profile of the two mostly isolated Enterobacter spp., Enterobacter aerogenes and Enterobacter cloacae complex. Methodology: A retrospective data analysis of patients reported at Grey’s; Harry Gwala and Northdale hospitals from 2018-2021 was performed. Target sample was specifically for sensitivity profile of Enterobacter aerogenes and Enterobacter cloacae complex from both inpatients and outpatients infected by the gram-negative ESKAPE reported at those 3 hospitals. Following health sciences ethics committee (HSREC) and National Health Laboratory Service (NHLS) approvals, data were retrieved from the NHLS Central Data Warehouse through the Academic Affairs and Research Management Systems (AARMS). Results: A total of 1746 non-duplicate Enterobacter spp. strains isolated from inpatients and outpatients were retrieved, 86% were Enterobacter cloacae complex and the remaining 13.7% were Enterobacter aerogenes. Discussion: Enterobacter cloacae complex showed minimal resistance to all tested carbapenems with meropenem being the highest of the three at 5, 4%. Enterobacter aerogenes showed a similar pattern as far as carbapenems resistance are concerned. Although the resistance to carbapenems such as imipenem and meropenem were found to be relatively low in the Enterobacter species, analysis also showed an increasing trend post-COVID-19 era. Conclusion and recommendations: This analysis reveals not so alarming but significant changes in resistance rates for several antibiotics, particularly in the A. cloacae complex. Providing ongoing education and training for healthcare workers on the importance of antimicrobial agent stewardship and infection control practices is paramount to prevent further increase in resistance. Future research should aim to expand surveillance networks to include more hospitals and regions within South Africa. This would provide a more comprehensive understanding of antimicrobial resistance patterns and facilitate timely interventions.