A study conducted in three Nigerian hospitals found that nearly half of Pseudomonas aeruginosa isolates were resistant to all antibiotics tested, researchers reported yesterday in JAC-Antimicrobial Resistance.
In the study, a team of researchers from Nigeria and Germany conducted whole-genome sequencing and antibiotic susceptibility testing on strains of P aeruginosa isolated from wounds (88 isolates), urine/catheter tips (25), sputum/tracheotomy aspirates (5), ear swabs (4), and vaginal swabs (1). The aim of the study was to determine the antibiotic susceptibility patterns of P aeruginosa, which is typically resistant to multiple antibiotics, and identify antimicrobial resistance genes. The researchers were particularly interested in carbapenemase genes, since carbapenem resistance can severely limit the treatment options for P aeruginosa infections.
Of the 123 isolates analyzed, 43% were resistant to all five antibiotic classes tested (penicillins, cephalosporins, carbapenems, aminoglycosides, and fluoroquinolones), 44% were resistant to imipenem, and 39% were resistant to imipenem. Among the meropenem-resistant isolates, 89% carried at least on carbapenemase gene. The most prominent carbapenemase gene was blaNDM-1, which conferred resistance to all five antibiotic classes and increased the minimum inhibitory concentrations from meropenem and imipenem.
The exceptional prevalence of carbapenemases, particularly blaNDM-1, in Nigerian hospitals highlights the global rise in carbapenem resistance mediated by carbapenemases.
The study authors note that the isolate were from secondary and tertiary hospitals, which tend to have a larger proportion of patients with severe infections that require increased carbapenem use, resulting in increased selection for carbapenem-resistant bacteria. Nonetheless, they say the results suggest antibiotic resistance in hospitals in western Africa is increasing and needs to be addressed.
"The exceptional prevalence of carbapenemases, particularly blaNDM-1, in Nigerian hospitals highlights the global rise in carbapenem resistance mediated by carbapenemases and emphasizes the necessity of limiting the continuing spread of antimicrobial resistance," they wrote. "This can be achieved by controlling and reducing antibiotic use in agriculture, by adequate wastewater treatment, and by implementing routine susceptibility testing, antibiotic stewardship programmes, and improved hygiene measures in hospitals to limit the application of last-resort antibiotics and the spread of highly resistant bacteria."