Publications des agents du Cirad

Cirad

Developments in diagnostics and antibiotic resistance of coagulase positive, maltose negative staphylococci from milk of dairy cows

Karzis J., Petzer I.M., Donkin E.F., Naidoo V., Etter E.. 2019. In : IDF Mastitis Conference 2019: Abstract book. Copenhague : IDF, p. 31. IDF Mastitis Conference. 7, 2019-05-14/2019-05-16, Copenhagen (Danemark).

DOI: 10.13140/RG.2.2.21103.28324

In South Africa, as is done with routine Veterinary diagnostics worldwide, focus is on a fast turnaround time and relatively low cost. Staphylococci are identified using the coagulase test (Staphylase test, Oxoid). In more recent years, further diagnosis of coagulase positive staphylococci on maltose agar has been known to differentiate Staphylococcus aureus (S. aureus) from Staphylococcus intermedius group staphylococci (SIG), which comprises of S. pseudintermedius, S. intermedius, S. delphini and others. This became important due to the increase of coagulase positive maltose negative isolates (SIG) in dairy herds in South Africa in recent years, after first being identified in 2006. These organisms was responsible for low somatic cell count (SCC) and showed no antibiotic resistance, unlike the maltose positive S. aureus. The objective of this study was to confirm identification and investigate the seasonal, regional and SCC effects on antibiotic resistance of this emerging pathogen maltose negative S. aureus, initially phenotypically identified as potential SIG, of which little is known. In this study samples identified during routine diagnosis (phenotypic) as potential SIG (coagulase positive, maltose negative staphylococci), were sent for further diagnosis on Matrix Assisted Laser Desorption/Ionisation Time-of- Flight Mass Spectrometry (Maldi Tof, Bruker) and for genotypic identification using 16s RNA ribosomal sequencing and multi locus sequence typing (MLST) to confirm the diagnosis. This study analysed retrospective data of 272 of these isolates from milk samples (2009 to 2017). These isolates were tested for antibiotic resistance using the disc diffusion (Kirby Bauer) method for ampicillin, cloxacillin, penicillin G, clindamycin, oxy-tetracycline, cephalexin, cefuroxime, tylosin and cefoxitin, with clinical breakpoints established by CLSI. The samples were from 117 dairy herds, out of the estimated 2000 commercial dairy herds in South Africa. Further testing

Documents associés

Communication de congrès

Agents Cirad, auteurs de cette publication :