QUINOLONE – RESISTANT SALMONELLA TYPHI IN IBADAN, NIGERIA

Abstract

Typhoid fever remains prevalent worldwide especially in a developing country like Nigeria. Many first line drugs such as chloramphenicol were discontinued due to multi-drug resistant (MDR) Salmonella typhi (S. typhi). Quinolones are now the recommended therapy but, in spite of their usefulness, there are several reports of failure of therapy due to quinolone resistance. This study sought to find the prevalence of quinolone resistant and MDR S.typhi and also to determine factors associated with typhoid fever and antibiotic resistance in this environment. Patients suspected to have typhoid fever and other acute febrile illnesses were recruited from several centers within Ibadan. After an interview, blood and, in some cases, stool samples were collected for culture. Isolates were confirmed using morphology, biochemical and serological tests. Disk diffusion antibiotic susceptibility testing was carried out for chloramphenicol, ampicillin, amoxicillin, amoxicillinclavulanic acid, nalidixic acid, ciprofloxacin, azithromycin and ceftriaxone. The minimum inhibitory concentration of ciprofloxacin was determined by broth macrodilution technique. One hundred and forty six (4.6%) out of the 3184 patients recruited for the study had blood cultures positive for Salmonella typhi. Other organisms isolated were predominantly Staphylococcus aureus and Escherichia coli. Of Salmonella typhi isolates 37.7%, 32.2%, 38.4%, 50.7%, 87.7%, 91.1%, 95.9%, 99.3% and 100% were susceptible to chloramphenicol, cotrimoxazole, ampicillin, amoxicillin, amoxicillin-clavulanic acid, nalidixic acid, ciprofloxacin, azithromycin and ceftriaxone respectively. The MIC50 and MIC90 of ciprofloxacin were 0.06 and 0.125µg/ml respectively. The prevalence of multidrug resistance was 56.2% while that of quinolone resistance was 8.9%. History of previous multiple antibiotics use was found to be associated with quinolone resistance. Quinolones remain useful in treating typhoid fever in this environment. The use of chloramphenicol and other previous first line antibiotics should be discouraged due to the high prevalence of multidrug resistant Salmonella typhi. Efforts should be geared towards improving general living conditions of the population to control typhoid fever.

QUINOLONE – RESISTANT SALMONELLA TYPHI IN IBADAN, NIGERIA