| Literature DB >> 28824577 |
Sudipta Mahato1, Hiral U Mistry1, Shalini Chakraborty1, Paresh Sharma1, R Saravanan2, Vasundhra Bhandari3.
Abstract
Methicillin resistant Staphylococcus aureus causing bovine mastitis has been very well investigated worldwide. However, there are only limited reports on the characterization of methicillin resistant and sensitive coagulase negative staphylococci (CoNS) across the globe. Hence, in the present study, we aim to determine the phenotypic traits based on antimicrobial susceptibility profile and genotypic characterization by verifying the presence of resistance determinants, virulence and toxin genes present in the CoNS causing clinical mastitis. We obtained 62 CoNS isolates from 167 mastitic milk samples collected from three different states of India. The 62 isolates comprises of 10 different CoNS species S. sciuri, S. haemolyticus, S. chromogenes, S. saprophyticus, S. xylosus, S. simulans, S. agnetis, S. epidermidis, S. gallinarum, and S. cohinii. Susceptibility screening against 11 antibiotics determined 45.16% isolates as multidrug resistant (resistant to more than two class of antibiotic), 46.74% resistant (one or two antibiotic class) and 8.06% isolates were pan-sensitive (sensitive to all drugs). High resistance was observed against oxacillin and cefoxitin, whereas all isolates were susceptible toward vancomycin and linezolid. Fifty three isolates were methicillin resistant and 9 isolates were sensitive as determined by oxacillin susceptibility assay. The methicillin resistance gene, mecA was found in 95.16% isolates and staphylococcal cassette chromosome mec (SCCmec) typing predominantly revealed Type III (n = 34) and Type V (n = 18). Interestingly, 11.9% of mecA positive isolates were oxacillin susceptible and referred as oxacillin susceptible mecA positive staphylococci (OS-MRS). Additionally, genes encoding for enterotoxin, (sea, seb, seh, see) toxic shock syndrome (tsst), exfoliatin (eta, etb, etd) and virulence (pvl, Y-hlg) were also screened. Of all the genes examined, 67.74% of isolate were positive for the Y-hlg gene, followed by the sea gene in 25.8% whereas in none of the isolates the eta and the etb gene was amplified. The study also highlights the incidence of clinical isolates of CoNS, which are harboring the toxin and the virulence genes rendering them as a more potential threat. This is the first report of animal origin OS-MRS from India, which emphasizes on the inclusion of both the genetic and phenotypic test for proper characterization of CoNS and preventing resistant strain misidentification.Entities:
Keywords: OS-MRS; antibiotic susceptibility; bovine mastitis; coagulase negative staphylococci; pvl gene
Year: 2017 PMID: 28824577 PMCID: PMC5534481 DOI: 10.3389/fmicb.2017.01446
Source DB: PubMed Journal: Front Microbiol ISSN: 1664-302X Impact factor: 5.640
Details of primers used in the study.
| S. No. | Gene name | Sequence | Amplicon Size | Reference |
|---|---|---|---|---|
| 1 | >1.2 Kb | |||
| 2 | 162 bp | |||
| 3 | 138 bp | |||
| 4 | 552 bp | |||
| 5 | 270 bp | |||
| 6 | 317 bp | |||
| 7 | 170 bp | |||
| 8 | 617 bp | |||
| 9 | 190 bp | |||
| 10 | 612 bp | |||
| 11 | 452 bp | |||
| 12 | 499 bp | |||
| 13 | 937 bp | |||
| 14 | 118 bp | |||
Characterization of the coagulase negative staphylococci clinical isolates causing bovine mastitis.
| Name of the Species | Regional Distribution | Number of Isolates | Multidrug Resistant | Resistant | Sensitive | Toxin genes | Virulence genes |
|---|---|---|---|---|---|---|---|
| Telangana-14 | 20 | 10 | 10 | 0 | |||
| Andhra Pradesh-6 | |||||||
| Telangana-2 | 13 | 3 | 9 | 1 | |||
| Andhra Pradesh-7 | |||||||
| Tamil Nadu-4 | |||||||
| Telangana-4 | 10 | 7 | 1 | 2 | |||
| Tamil Nadu-6 | |||||||
| Telangana-6 | 6 | 1 | 5 | 0 | |||
| Telangana-5 | 5 | 5 | 0 | 0 | |||
| Tamil Nadu-2 | 2 | 2 | 0 | ||||
| Telangana-1 | 2 | 1 | 1 | 0 | |||
| Tamil Nadu-1 | |||||||
| Andhra Pradesh-1 | 2 | 1 | 1 | ||||
| Tamil Nadu-1 | |||||||
| Telangana-1 | 1 | 1 | 0 | 0 | |||
| Telangana-1 | 1 | 0 | 1 | 0 | |||
Characteristics of the seven oxacillin susceptible mecA positive Coagulase negative Staphylococci (OS-MRS).
| Isolate ID | Species | Region | Oxacillin MIC (μg/ml) | mecA gene | SCC mec type | Multidrug resistant (MDR) / Resistant (R) / Sensitive (S) | Toxin genes | Virulence genes |
|---|---|---|---|---|---|---|---|---|
| TG-25 | Telangana | 0.31 | + | 3 | R | Nil | Nil | |
| TG-31 | Telangana | 0.31 | + | 3 | S | etd | Nil | |
| TG-58 | Telangana | 0.31 | + | 3 | R | sea, seb | Ý-hlg | |
| TG-68 | Telangana | 0.31 | + | 3 | S | Nil | Ý-hlg | |
| TN-29 | Tamil Nadu | 0.31 | + | 3 | S | Nil | Ý-hlg | |
| TN-30 | Tamil Nadu | 0.31 | + | 3 | S | seh, tsst | Ý-hlg | |
| TN-37 | Tamil Nadu | 0.31 | + | 3 | S | seh | Ý-hlg | |