Fluoroquinolones Resistance and Plasmid Profile Patterns of Typhoidal Salmonella Serovars Isolated from Human Faecal Samples in Tertiary Hospitals in South-East, Nigeria

Abstract

Antimicrobial resistance associated with salmonellosis is a major global public health challenge. This study investigated the resistance and plasmid profile patterns of typhoidal Salmonella serovars isolated from human faecal samples to commonly used fluoroquinolones. A total of 300 faecal samples were collected from three tertiary hospitals in South-East Nigeria. The isolates were characterized using standard phenotypic, molecular and antibiogram studies. Antibiogram studies were evaluated using ciprofloxacin and ofloxacin discs. Data were analysed with descriptive statistics, t-test and 2-way analysis of variance. Out of 300 faecal samples, (129) 43% yielded Salmonella spp and (62) 48% were confirmed to be typhoidal Salmonella serovars. The antibiogram study on the 62 typhoidal Salmonella serovars showed that ( 22) 35 % and (4) 7 % were sensitive, ( 27) 44 % and (28) 45 % were intermediate, ( 13) 21 % and (30) 48 % were resistant to ciprofloxacin and ofloxacin respectively. The plasmid profile revealed the presence of DNA with molecular weight ranging from 10 to 37 kb. The isolates had higher molecular weight than the control that was used for the plasmid profiling. On exposure to a curing agent (acridine orange), all the resistant isolates became sensitive. This study showed that the incidence of resistant typhoidal Salmonella to most commonly used fluoroquinolones is high in South-East Nigeria and this could be as a result of plasmid resistant DNA. It also indicated that the indiscriminate use of ciprofloxacin and ofloxacin within the South-East region of Nigeria may increase the typhoidal Salmonella resistance.