Resistance Patterns and Phenotypic Detection of β-lactamase Enzymes among Enterobacteriaceae Isolates from Referral Hospitals in Khartoum State, Sudan

Background Beta-lactamase enzymes-producing Enterobacteriaceae have emerged in many hospital settings resulting in poor treatment outcomes. We aimed to determine resistant patterns of Beta-lactamase enzymes among Enterobacteriaceae collected from referral hospitals in Khartoum state, Sudan. Methods A total of 168 Enterobacteriaceae recovered from clinical samples of patients during May 2014 to February 2015. Identification and susceptibility testing of the isolates were performed as per standard methods. Double-disk synergy test was applied to determine the presence of extended-spectrum β-lactamase (ESBL) production. AmpC beta-lactamases and carbapenemase were screened using AmpC disk test and the modified Hodge test, respectively. Results ESBL-producing Enterobacteriaceae represented 45.2%, with a higher rate among K. pneumoniae. AmpC beta-lactamase detected as 49.3%, with peak levels among Acinetobacter baumannii (A. baumannii) (83.3%) and Enterobacter cloacae (75%). Carbapenemase production was found among 74.5% of isolates, with high rates among A. baumannii (89%) and K. pneumoniae (78%). Overall Enterobacteriaceae, highest resistance rates were found in penicillins and cephalosporins agents. Amikacin and imipenem revealed good activities against most of the isolates, except for A. baumannii (66.7% and 75%, respectively). E. coli yielded high resistance rates for amoxicillin (98.8%), amoxicillin-clavulanic acid (93.8%), cefotaxime (93.8%), and ciprofloxacin (76.5%). Moderate resistance rates were observed among K. pneumoniae for ciprofloxacin (61.5%), nitrofurantoin (57.7%) and cefoxitin (40.4%). Conclusions ESBL, AmpC beta-lactamase and carbapenemase-producing Enterobacteriaceae are emerging and may contribute to increasing antimicrobial resistance in Sudan. Phenotypic screening of such enzymes is rapid and straightforward and should be simultaneously done and carried out routinely in our hospitals.