Theses and Desertations

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Browsing Theses and Desertations by Author "ADEBIYI, INI"

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    PREVALENCE OF AMPICILLINASE C, EXTENDED-SPECTRUM AND METALLO-ΒETA-LACTAMASE GENES IN GRAM-NEGATIVE ESKAPEE BACTERIA ISOLATED FROM TERTIARY HOSPITALS IN SOUTHWEST NIGERIA
    (2024-01-25) ADEBIYI, INI
    ABSTRACT Gram-negative ESKAPEE bacteria (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species and Eschericia coli) have been reported globally as leading causes of nosocomial infections. The major mechanism of antibiotic resistance in these bacteria is the production of drug resistant enzymes such as extended-spectrum-β-lactamase (ESBL), metallo-β-lactamase (MBL), and Ampicillinase-C β-lactamase (Amp-C). This study determined antibiotic resistance patterns, detect production of β-lactamase enzymes and resistant genes among Gram negative ESKAPEE bacteria. A total of 283 clinical Gram-negative bacterial isolates from blood, wound, urine and lower respiratory tract samples of in-patients were collected from three tertiary hospitals in Southwest Nigeria (University College Hospital, Ibadan, Federal Medical Centre, Abeokuta and Obafemi Awolowo University Teaching Hospital, Ile-Ife). Isolates were confirmed by standard biochemical tests and antibiotic susceptibility patterns were determined using the Kirby-Bauer disc diffusion method. Phenotypic detection of Amp-C, ESBLs, and MBLs was confirmed using Three-dimensional extract, Double-disc Synergy and combined disk tests, respectively. Polymerase Chain Reaction was performed on positive phenotypic isolates to detect resistance genes using specific primers. Statistical significance of data was tested using Chi-square with 95% confidence interval. Most of the isolates (97.5%) were multidrug resistant (MDR) with Acinetobacter baumannii being 100% resistant to seven out of the ten antibiotics tested. Isolates showed least (41.0 %) and highest (96.5%) resistance to Meropenem and Ampicillin respectively. Resistance to Meropenem among K. pneumoniae, Enterobacter aerogenes and P. aeruginosa isolates from UCH was significantly (72.4%, 87.5% and 70.0%) higher than from other hospitals, respectively. Phenotypically, the prevalence of AmpC, MBL and ESBL were 19.9%, 19.4% and 13.5%, respectively. Multiple phenotypic β-lactamase production was observed in 30 isolates but was statistically significant (80%) in isolates from UCH. Wound samples from surgical wards had the highest prevalence of ESBL (15.8%), AmpC (15.6%) and MBL (16.4%) phenotypes respectively. Majority of the AmpC (95% - 100%), ESBL (80% - 100%), and MBL (93.5% - 100%) isolates except P. aeruginosa were resistant to Ciprofloxacin and third generation Cephalosporins. MBL-producing P. aeruginosa showed resistance to Ceftazidime (60%) and Ciprofloxacin (70%). The detection rate was 9.2% for MBL, 5.7% for ESBL and 3.5% for AmpC genes. The most predominant ESBL resistant gene was blaSHV (75%) while blaFOX (62.5%) was detected as the most predominant AmpC resistant gene. Two genes blaVIM (42.3%) and blaIMP (42.3%) were equally predominant among MBL genes. These genes occurred mostly in K. pneumoniae (32%) and E. coli (28%) isolates. All isolates encoding ESBL and MBL genes were MDR while all the isolates encoding AmpC genes were extensively drug resistant. Surgical wards had majority of isolates encoding AmpC (37.5%) and MBL (26.9%) genes while the urology and gynecology wards had majority (18.8%) of isolates with ESBL genes. This study revealed a high prevalence of beta-lactamase-producing Gram-negative bacteria in hospitalized patients and showed that there is high risk of multidrug resistant pathogens spreading among hospitalized patients in tertiary healthcare facilities in Southwest Nigeria.