Antibiotic resistance profiles of clinical and environmental isolates of Pseudomonas aeruginosa in Calabar, Nigeria

Abstract

Healthcare-associated infections due to multidrug-resistant Gram-negative bacteria, including Pseudomonas aeruginosa have become increasingly difficult to treat. The hospital environments, particularly in ICUs, are common habitats for Pseudomonas aeruginosa. Spread of pathogen may occur through direct patient contact with contaminated formites and from patient-to-patient on the hands of healthcare workers. The present study was conceived to evaluate the antibiotic resistance profiles of clinical and environmental isolates of Pseudomonas aeruginosa in Calabar Metropolis. A total of 1000 different clinical specimens were non- repetitively obtained from patients in four health care facilities in Calabar while 75 samples were also collected from the hospitals environment. From these specimens, 197 clinical isolates were recovered.whereas 26 environmental isolates were identified. Pus/wound swab produced the highest number of clinical P. aeruginosa isolates 83(42.1%) followed by ear swab 53(26.9%); surgical wound swab 24(12.2%); eye swab 14(7.1%); respiratory secretions 12(6.1%); mid-stream urine 7(3.6%) and blood specimens 4(2.0%) in that order. The highest number of environmental isolates 12(46.2%), were recovered from the hospital floors whereas only one (3.8%) isolate was recovered from drug dispensing tray. Antibiotic susceptibility testing was done using 12 agents from six classes of antibiotics and included antipseudomonal penicillin - carbenicillin; aminoglycosides - amikacin, gentamicin and tobramycin; fluoroquinolone - ciprofloxacin; cephalosporin - ceftazidime, ceftriaxone and cefepime; monobactam - aztreonam; carbapenem - imipenem, meropenem and doripenem. The isolates exhibited highest resistance (>70%) to the cephalosporins while 30(15.2%) clinical isolates were carbapenem-resistant. None of the environmental isolates was resistant to the carbapenems and the monobactam, aztreonam. The overall prevalence of Pseudomonas infection in Calabar from the study was 19.7%. On the other hand, prevalence of carbapenem-resistant P. aeruginosa (CR-PA) was 15.2%. Although the clinical use of carbapenems is quite low in Calabar, resistance to this very important class of antibiotics already exists. This calls for surveillance and the judicious use of carbapenems for only infections that defy all other treatment options.