Diversity of antibiotic resistance genes and staphylococcal cassette chromosome mec elements in faecal isolates of coagulase-negative staphylococci from Nigeria.
BACKGROUND
Coagulase-negative staphylococci (CoNS) are opportunistic pathogens found as colonisers of the human gut. This study was carried out to examine the genetic resistance mechanisms in faecal isolates of CoNS. The study investigated 53 non-duplicate CoNS isolates obtained from the fresh stool samples of apparently healthy subjects in the community of Ile-Ife, South-Western Nigeria. Antibiotic susceptibility testing was assessed by the disc diffusion test while antibiotic resistance genes were analysed by PCR. mecA positive isolates were analysed by Staphylococcal Chromosome Cassette mec (SCCmec) and cassette chromosome recombinase (ccr) complex typing methods.


RESULTS
Resistance genes were detected only in isolates that showed resistance by phenotypic screening. The aac(6')-aph(2") gene was detected in all the three isolates resistant to gentamicin. Four of the five erythromycin resistant isolates were positive for the ermC gene, the remaining isolate carried the msrA gene. The tetK gene was detected in 6 of the 7 tetracycline resistant isolates while 4 possessed the tetM gene. Three of the isolates (S. haemolyticus, S. xylosus and S. capitis) had both genes. Several SCCmec types were found: SCCmec I- ccrABβ2-α2 (4 isolates: 3 S. epidermidis, 1 S. warneri), SCCmecIVb- ccrABβ2-α3 (1 isolate: S. epidermidis), SCCmecIVd- ccrABβ2-α3 (8 isolates: 3 S. epidermidis, 2 S. xylosus, 1 S. saprophyticus, 1 S. warneri, 1 S. capitis), and untypable (2 isolates: S. epidermidis).


CONCLUSIONS
This genetic background could be a reservoir for interspecies gene transfer among CoNS and S. aureus in the intestinal tract.
Luca Agostino
LA
Vitali
Dezemona
D
Petrelli
Adebayo
A
Lamikanra
Manuela
M
Prenna
School of Pharmacy, University of Camerino, Camerino, Italy. eoakinmi@oauife.edu.ng.
Ezekiel Olugbenga
EO
Akinkunmi
D000328:Adult; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005243:Feces / Q000382:microbiology*; D005798:Genes, Bacterial; D014644:Genetic Variation; D064368:Healthy Volunteers; D006801:Humans; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D009549:Nigeria; D016133:Polymerase Chain Reaction; D013210:Staphylococcus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*