Clostridium difficile in broiler chickens sold at market places in Zimbabwe and their antimicrobial susceptibility

Abstract

Clostridium difficile has been shown to be a nosocomial pathogen associated with diarrhoea and pseudomembranous colitis in hospitalised patients and the infection is believed to be acquired nosocomially. Community-acquired C. difficile-associated diarrhoea has also been reported. Recent studies have shown the occurrence of C. difficile in food animals which may act as a source of infection to humans. The aim of this study was to determine the occurrence of C. difficile in broiler chickens sold at market places in an urban area in Zimbabwe. Faeces of broiler chickens were collected from the cages at the market places and soils were collected from areas around the market places. The chicken faeces and soil samples were cultured for C. difficile. The C. difficile isolates were tested for toxins A or B production as well as for their susceptibility to antimicrobial drugs. C. difficile was isolated from 29.0% of 100 chicken faeces samples and 22.0% of 100 soil samples. Some of the C. difficile isolates from chickens (89.7%) and soils (95.5%) were toxigenic. All the isolates were susceptible to metronidazole, vancomycin, doxycycline, chloramphenicol and tetracycline. Over 70% of the isolates were susceptible to erythromycin, co-trimoxazole and ampicillin. They were all resistant to cefotaxime, gentamicin, ciprofloxacin, norfloxacin and nalidixic acid. The results of the present study suggest that broiler chickens sold at market places in the urban area are an important source of C. difficile, which may infect humans through consumption of chicken meat.

Introduction

Clostridium difficile is recognised as a nosocomial pathogen associated with antimicrobial drug-associated diarrhoea and pseudomembranous colitis in humans (George et al., 1977, George et al., 1978) and the infection is believed to be acquired nosocomially. The antimicrobial agents most frequently associated with Clostridium difficile-associated disease (CDAD) include clindamycin, cephalosporins and ampicillin but almost all antibiotics can cause the disease (Mylonakis et al., 2001). More recently, fluoroquinolones were found to be an important risk factor for CDAD (Pepin et al., 2005). C. difficile has also been shown to be an important pathogen causing diarrhoea in humans in communities outside hospital environments (Riley et al., 1991, Riley et al., 1995, Kyne et al., 1998). Incidence and severity of the disease appear to be increasing (McDonald et al., 2006). Moreover, C. difficile is also an important causative agent of diarrhoea in HIV/AIDS patients (Barbut et al., 1997, Willingham et al., 1998). The C. difficile strains associated with diarrhoea and pseudomembranous colitis produce either toxin A (an enterotoxin) or toxin B (a cytotoxin) or both toxins. Some strains do not produce toxins and do not cause the two conditions. C. difficile also appears to be an important cause of enteric disease in other species such as pigs (Songer et al., 2000), dogs (Marks et al., 2002) and horses (Arroyo et al., 2004).

Food animals are an important source of human enteropathogenic micro-organisms and can be spread to humans through consumption of foods of animal origin. In recent studies C. difficile has been isolated from food animals such as poultry and sheep (Al Saif and Brazier, 1996), pigs (Songer et al., 2000, Songer and Anderson, 2006), chickens, goats and cattle (Simango, 2006) and calves (Rodriguez-Palacios et al., 2006). Moreover, molecular typing of C. difficile isolates from calves and humans has shown similarities in PCR ribotypes from the two species including two PCR ribotypes associated with outbreaks of severe disease in humans (Rodriguez-Palacios et al., 2006), suggesting that cattle may be reservoirs of C. difficile for humans. The aim of this study was to determine the occurrence of C. difficile in live broiler chickens sold at market places in Harare, Zimbabwe.