Co-colonization by antimicrobial resistant thermophilic Campylobacter and Escherichia coli in the intestines of local chicken presented for disposal at vending areas in Morogoro Municipality, Tanzania

Abstract

Although carriage of multiple potential human pathogens in known reservoirs is not uncommon, investigations addressing more than one of the pathogens in these reservoir populations are rare in Tanzania. Cloaca swabs were collected from 400 scavenging local chickens (SLC) and conveyed in Bolton broth and maximum recovery diluent for isolation of thermophilic Campylobacter and E. coli, respectively. Isolation of thermophilic Campylobacter adopted the Capetown protocol. The isolates were identified using phenotypic tests and eventually confirmed by polymerase chain reaction. Isolation of E. coli was done on McConkey agar and further detection of pathogenic E. coli was done on sorbitol MacConkey agar. Isolates were identified by the IMViC test and the Analytical Profile Index. Both, thermophilic Campylobacter and E. coli isolates were tested for resistance against eight commonly used antimicrobial agents in veterinary and human medicine in the study area using the disc diffusion method. Thermophilic Campylobacter were detected in samples from 51 birds (12.75%), most of them carrying C. jejuni. The proportion of SLC colonized with E. coli was 81.0%, of which 7.4% were colonized with pathogenic E. coli. Co-colonization by both thermophilic Campylobacter and E. coli was detected in 9.75% of the collected samples, 28.2% of them involving pathogenic E. coli. All the thermophilic Campylobacter isolates were resistant to cephalothin; and more than half (88.2%) to amoxycillin. Resistance to macrolides and quionlones occurred at lower frequencies. A higher frequency of E. coli isolates (91.7%) was resistant against cephalothin. Slightly lower frequencies of E. coli isolates were resistant to gentamycin, amoxicillin and erythromycin. Significantly lower frequencies of resistance were noted for nalidixic acid, ciprofloxacin, norfloxacin and azithromycin. Multidrug resistant isolates were found in 31.5% and 27.8% of thermophilic Campylobacter and E. coli isolates, respectively. SLC are reservoirs of antimicrobial resistant thermophilic Campylobacter and E. coli isolates, and are thus potential sources of human infections with these organisms. The birds should be among the targets when control of human infections with these organisms focuses at reservoir level.

Keywords: E. coli, Scavenging local chickens, Tanzania, Thermophilic Campylobacter