Genotypic and phenotypic resistance traits of gram-negative bacteria isolated from clinical and environmental sample, Jimma University Hospital, Jimma Zone, Ethiopia

Introduction: Antibiotic resistances due to extended-spectrum β-lactamases (ESBLs), AmpCs and carbapenemases have become a major health concern globally and also in Ethiopia. Data on the frequency and molecular characterization of this β-lactamases is scarce or non-existant in Ethiopia. The aim of this study was, therefore, to determine the frequency, susceptibility patterns and molecular characteristics of ESBLs, AmpC and carbapenemases in clinical and environmental isolates of gram-negative bacilli (GNB) in Jimma university specialized hospital (JUSH), in southwest Ethiopia. Materials and Methods: 224 non-duplicate and pure isolates obtained from clinically apparent infections and 29 isolates recovered from stethoscopes were included in the study. Identification of the isolates was performed by MALDI-TOF mass spectrometry. Susceptibility testing and phenotypic detection of ESBLs, AmpCs and carbapenemases was performed using Vitek 2 Compact System and MASTDISCSTM AmpC/ESBL Detection set and analyzed using EUCAST breakpoints. Genotypic analysis was performed using Check-MDR CT103 Microarrays. Results: Of the total clinical isolates (n=224), 112 were screen positive for ESBLs. Of these 63.4% (71/112) tested positive for ESBLs encoding genes by Check-MDR array, which corresponds to 91.8% (67/73) of the total Enterobacteriaceae and 10.3% (4/39) of lactose nonfermenting gram-negative bacilli. Among the total ESBLs genes positive isolates, 95.8% (68/71) carried blaCTX-M genes with CTX-M group 1 being the predominant CTX-M Geno-group (97.1%). Among the 122 with positive phenotypic screening test for AmpC beta-lactamases, 23% (n=28) were found positive for AmpC genes. A total of 30 AmpC genes were detected, of which, ACT/MIR were the most common AmpC gene (n=16) followed by DHA (n=12), and one each belonging to CMY and FOX. Among the carbapenem resistant or intermediate isolates (n=12), three clinical isolates of Acinetobacter baumannii were found NDM-1 positive. Of the 51 stethoscopes surveyed, 54.9% (n=28) were found to be contaminated with gram-negative bacilli. 55.2%, and 17.2% of these isolates (n=29) were found positive for ESBLs and AmpC genes, respectively. Conclusions: This study demonstrates a remarkably high prevalence of blaCTX-M genes and revealed the presence of NDM-1 for the first time in Ethiopia. The high level of resistance to β-lactam and non-β-lactam antibiotics and the detection of NDM-1 are alarming and emphasize the need for implementation of strict infection control measures and judicious use of antibiotics in the local setting as well as in the whole region