Distribution of antibiotic resistance genes in rodent droppings in a hospital environment

BACKGROUND: The interaction of rodents with humans in the hospital environment may facilitate transmission of multidrug-resistant (MDR) bacteria. This study investigated the presence of genes harboured by the antibiotic-resistant bacteria in rodent droppings from nine locations in the Federal University Teaching Hospital (FUTH), Owerri, by using a purposive sampling method. Standard microbiological techniques were used to isolate and identify the bacteria present, followed by antibiotic sensitivity via the broth dilution method and antibiotic resistance genes by conventional polymerase chain reaction (PCR). RESULTS: Five species of bacteria were isolated and identified as Staphylococcus sciuri subsp.lentus, Staphylococcus gallinarum, Raoultella ornithinolytica, Leuconostoc lactis, and Burkholderia cepacia complex. The bacteria demonstrated low MIC values below their respective resistance thresholds for gentamicin and intermediate susceptibility to ciprofloxacin and levofloxacin. Three (3) isolates (12.5%) were defined as MDR, with resistance to three (3) antimicrobial classes, while the remaining isolates were resistant to one or two classes and were thus defined as non-MDR. MDR was detected only in Raoultella ornithinolytica isolates from MW10. Isolates from FW7, MW6, HH, KA, SS, OR, HR, and MS were resistant particularly to β-lactams, as well as tetracyclines or macrolides, but it was not sufficient for MDR classification. SHV and TEM antibiotic resistance genes were seen in Raoultella ornithinolytica and Burkholderia cepacia complex, respectively, while MsrA was seen in Staphylococcus spp. CONCLUSION: The findings show that rodent droppings in the hospital environment contained antibiotic-resistant bacteria and selected resistance gene markers. These findings provide preliminary, context-specific evidence of environmental contamination and highlight the need for improved sanitation, rodent control, and further studies using larger and more representative samples.