Phenotypic and genotypic characterization of plasmid-mediated AmpC beta-lactamases in enteric Gram-negative bacteria from patients with lower respiratory tract infections in a tertiary hospital, southwest Nigeria

Background: AmpC or class C or group 1 beta lactamases are class C cephalosporinases that hydrolyse a wide variety of beta-lactam antibiotics including alpha methoxy beta-lactams (cefoxitin), narrow and broad spectrum cephalosporins. This study was conducted to characterize plasmid-mediated AmpC producing enteric Gram- negative bacteria from patients with lower respiratory tract infections in Obafemi Awolowo University Teaching Hospital Complex (OAUTHC) Ile Ife, Osun State, Nigeria Methodology: A total of 149 patients with clinical features of lower respiratory tract infections (LRTI) were selected by simple random sampling for the study. All Gram-negative isolates recovered from standard microbiological cultures of respiratory specimens of these patients were tested against cefoxitin, third generation cephalosporins (3GCs), and other antibiotics using the disc diffusion AST method, and also screened for production of AmpC beta-lactamases phenotypically by the CLSI method. Plasmid DNA extraction was carried out on twenty-nine cefoxitin-resistant selected isolates using the Kado and Lin method, while genotypic detection of plasmid-mediated AmpC gene was carried out by the polymerase chain reaction (PCR) assay. Results: The results showed that 204 (43.3%) of 471 isolates recovered from the 149 selected patients were resistant to 3GC in the AST assay, among which 121 (59.3%) were resistant to cefoxitin, and 189 of the 471 isolates (40.1%) were AmpC producers. The AmpC producers concurrently showed multiple resistance pattern to other antibiotics tested in this study. Ninety six percent of the 29 selected isolates for plasmid analysis contained plasmids, 45% of which amplified positive on PCR for CMY, 38% for FOX, and 31% for ACC types of AmpC genes. Conclusion: This study showed a high degree of antibiotic resistance among enteric Gram-negative bacteria recovered from patients with LRTIs, as well as high degree of plasmid-encoded AmpC genes responsible for this high antibiotic resistance among the isolates. Proper antibiotic policy and regulation are required to limit the spread of plasmid mediated AmpC ß-lactamase

Bacterial Assessment of Electronic Hardware User Interfaces in Ile-Ife, Nigeria / Bacterial Assessment of Electronic Hardware User Interfaces in Ile-Ife, Nigeria

The study was undertaken to quantify and identify bacterial contaminants associated with private and open access user interfaces in various establishments in the town of Ile-Ife, Nigeria. The study was conducted in selected offices, business centres, banks and cybercafés within Ile-Ife. Swab samples were aseptically collected from each user interface (keyboard, mouse, ATM) and users? hands and cultured on nutrient and MacConkey agar, to determine the total bacterial load and coliform count, respectively, by the pour-plate technique. Bacterial loads present on different types of interface (keyboard, mouse and ATM) were found to be significantly different (p < 0.01). A total of 669 isolates comprising 11 distinct bacterial species were recovered from 313 randomly sampled user interfaces. The frequencies of occurrence of the species were Aerococcus viridans (9.4%), Bacillus spp. (8.4%), Enterobacter aerogenes (4.9%), Gaffkya tetragena (2.1%), Klebsiella pneumoniae (11.1%), Micrococcus luteus (10.9%), Moraxella catarrhalis (1.6%), Proteus spp. (10.6%), Pseudomonas aeruginosa (16.0%), Staphylococcus aureus (16.7%) and Staphylococcus epidermidis (8.2%). All the interfaces examined were contaminated. Contamination on interfaces in educational institutions differed significantly from that found in banks and cybercafés, but was comparable to that in commercial centres. Most isolates were resistant to amoxicillin, augmentin, nitrofurantoin and ceftriaxone, while resistance to ciprofloxacin and ofloxacin was the least frequent. Multiple antibiotic resistance was observed in 89.1% of bacterial isolates, with a total of 68 resistance patterns, resistance to three antibiotics being the most frequent (31.9%). About 74% of multiple antibiotic resistant isolates profiled for plasmid DNA contained either single or multiple plasmids. It was concluded that user interfaces were contaminated with potentially pathogenic bacteria, highly resistant to some commonly used antibiotics. These interfaces are therefore potential vehicles for the transmission of clinically important pathogens.