Methicillin-resistant Staphylococcus aureus (MRSA) isolated from raw milk and nasal swabs of small ruminants in Abeokuta, Nigeria.

Methicillin-resistant Staphylococcus aureus (MRSA), an important widespread cause of severe infection in both humans and animals, is a significant pathogen of public health concern. This study examined the presence of MRSA in 400 samples comprising 200 raw milks (145 from goat and 55 from sheep) and 200 nasal swabs (145 from goats and 55 from sheep) collected from ten different locations in Abeokuta, Nigeria. Samples were examined using standard bacteriological methods for the isolation and identification of Staphylococcus aureus and culture on oxacillin (6 µg/ml) and cefoxitin (2 µg/ml) selective media for the detection of MRSA. Suspected MRSA isolates were confirmed by latex agglutination test for the detection of penicillin-binding protein 2a (PBP2a). Antibiotic susceptibility testing was determined by Kirby Bauer disc diffusion method. Staphylococcus aureus was detected in 72 (18%) of 400 samples of which 52 (13%) were confirmed as MRSA. Methicillin-resistant S. aureus was detected in raw milk (37 of 200; 18.5%) and nasal swab (15 of 200; 7.5%). There was no significance difference (p > 0.05) in the prevalence of MRSA in sheep (37.7%) and goat (23.4%). The MRSA isolates showed resistance to ampicillin (100%), cloxacillin (100%), sulphamethoxazole-trimethoprim (100%), amoxicillin-clavulanate (84.6%), ceftriaxone (75%), cefuroxime (69.2%), erythromycin (65.4%), streptomycin (38.5%), ciprofloxacin (23.1%), pefloxacin (21.2%) and gentamicin (17.3%). The presence of multidrug-resistant MRSA in small ruminants reared in Abeokuta metropolis may be due to regular use of antibiotics and unhygienic practices by farmers. This in turn constitutes a potential public health risk to the owners, consumers of small ruminant products and the general populace.

Evolution of Salmonella nomenclature: a critical note.

Salmonellae are widely distributed but nomenclaturally controversial pathogens of both humans and animals. Despite elaborate studies, much still remain to be discovered about these organisms. Although Salmonella nomenclature has proved to be rather complex, in 2005, Salmonella enterica finally gained official approval as the type species of the genus Salmonella. In addition, one other species has been approved and recognised in the genus Salmonella, namely, Salmonella bongori. New serovars (serotypes) are continually being discovered each year and reported in the journal Research in Microbiology. Salmonella serovars and their antigenic formulae are listed in the White-Kauffmann-Le Minor scheme and updated by the World Health Organization's Collaborating Centre for Reference and Research on Salmonella at the Pasteur Institute, Paris, France.

Potentially zoonotic shiga toxin-producing Escherichia coli serogroups in the faeces and meat of food-producing animals in Ibadan, Nigeria.

Shiga toxin-producing Escherichia coli (STEC) are major food-borne pathogens associated with gastroenteritis and sometimes fatal haemolytic uraemic syndrome complication. Farm animals are asymptomatic carriers of STEC and contaminated meat is an important vehicle for zoonotic transmission from animals to humans. This study investigated the presence, virulence traits and antimicrobial susceptibility of seven potentially human pathogenic STEC serogroups (O157, O26, O91, O103, O111, O128 and O145) in the faeces and meat of food-producing animals in Ibadan, Nigeria. One hundred and fifty-four (7.3%) of 2133 samples were positive for STEC serogroups. The pathogens were detected in the faeces of cattle (15.2%), sheep (10.7%), goats (7.5%) and pigs (5.6%) as well as in beef (3.8%), goat-meat (1.7%) and pork (4.0%). All seven investigated STEC serogroups were found in cattle, all except O145 were found in sheep, three serogroups (O157, O26 and O111) were found in goats and three (O157, O111 and O128) in pigs. The rate of detection of each of the serogroups in all 2133 samples was: O157 (5.0%), O26 (0.2%), O91 (0.3%), O103 (0.3%), O111 (1.0%), O128 (0.2%) and O145 (0.1%). Of all 154 isolates, 11.0% had shiga toxin type 1 gene (stx(1)), 25.3% had stx(2) and 41.6% had stx(1)/stx(2); intimin gene (eaeA) was detected in 56.5% and enterohaemolysin gene (hlyA) in 75.3%. Among the O157 isolates, 24.5% were negative for stx genes but positive for eaeA and/or hlyA while 7.6% were negative for all four virulence genes. Fourteen different combinations of virulence genes were encountered but stx(1)/stx(2)/eaeA/hlyA combination was the most predominant. The percentage resistance of the isolates to the tested antimicrobial agents was: ampicillin (82.5%), chloramphenicol (42.9%), ciprofloxacin (22.1%), enrofloxacin (25.3%), nalidixic acid (37.7%), neomycin (24.0%), norfloxacin (20.8%), streptomycin (50.7%) and tetracycline (75.3%). One hundred and forty-eight (96.1%) of all 154 isolates were resistant to at least one of the tested antimicrobial agents while 69.5% were categorised as multi-drug resistant. Potentially pathogenic multi-drug resistant STEC isolates were recovered from the meat production chain in Nigeria. Unhygienic practices that predominate during slaughter and processing were observed to have contributed to faecal contamination and presence of STEC in meat.

Effect of three different routes of administration on the immunogenicity of infectious bursal disease vaccine.

The immune response of three groups of 10 chicks, vaccinated at age of 2 weeks against infectious bursal disease (Gumboro disease) via the oral, intramuscular and ocular routes, is compared. The vaccine was prepared by the NVRI (Vom, Nigeria). All chicks in the three groups remained seronegative 3 weeks after primary vaccination. However, precipitating antibodies were present in birds which received a booster dose at the age of 6 weeks. Post-vaccination seroconversion was observed at the age of 6 weeks in 70% of the birds vaccinated via the ocular route. This rate increased to 80% during the two following weeks and then decreased to 55.6% until the 10th week. In the groups vaccinated by the oral and intramuscular routes, the seroconversion rate in the 7th week was 30 and 33.3%, respectively, but increased to 87.5% in both groups at the end of the 10th week. Considering the age factor in the susceptibility of chicks to infectious bursal disease, the authors recommend the ocular route as the most effective for vaccination.