Study on the prevalence, molecular characterization and genomic analysis of Staphylococcus aureus causing subclinical mastitis in buffaloes
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Date
2023-06-15
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LUVAS Hisar
Abstract
Subclinical mastitis is relatively difficult to detect due to the absence of any visible
indications. Information about the prevalence of the disease along with associated risk factors in
Haryana is not available amidst their importance for public health and the economy. The goal of the
current study was to assess the prevalence ofsubclinical mastitis in buffaloes along with associated risk
factors with special reference to Staphylococcus aureus in the Haryana, molecular characterization of
antibiotic resistance, biofilm and virulence associated genes and further MLST (multi locus sequence
typing) analysis to define the sequence types of Staphylococcus aureus isolated from sub clinical
mastitis in buffaloes in Haryana.A total of 3200 quarter milk samples from 800 apparently healthy
lactating buffaloes from 20 districts of Haryana were analyzed.Overall prevalence of subclinical
mastitis in buffaloes of Haryana is observed 35.4%. This is the first report on prevalence of subclinical
mastitis and its associated risk factors in buffaloes of Haryana and the prevalence of Staphylococcus
aureus associated with SCM was 30.5%. Significant difference in prevalence of SCM was observed
quarter wise, leg tie of animal and type of roof. No significant difference in prevalence of SCM was
observed on basis of breed, pregnancy status, history of repeat breeding and visitor, vectors, milk yield,
lactation etc. Maximum sensitivity was recorded for Gentamicin (87.57%) against S.aureus isolates.In
the present study out of 519 Staphylococcus spp. isolated from bovine milk samples 352 isolates were
identified as S. aureus by PCR assay. Out of 352 Staphylococcus aureus isolates from subclinical
mastitis Methicillin resistant genes detected (mecA13.5%), biofilm forming (icaD11.64%,
icaA11.36%),Toxic shocks syndrome gene (Tsst-1 9.37%), Enterotoxin gene (sec 8.52%, sea 8.23%,
sed4.54%,seb 2.84%, see1.7%)and Exfiolative gene (etb3.97%, eta3.12%).
Performed MLST (multi locus sequence typing) analysis to define the sequence types isolated
from sub clinical mastitis in buffalo.Fourteen sequence type ST5113,ST5273, ST5420,ST5419,
ST79O4, ST1947,ST867, ST5180, ST2990, ST2454, ST4975, ST5416, ST5273, ssST3987:Three
clonal complex CC1,CC8,CC22 and four novel allele* gmk: Novel allele (isolate6),* arcC: Novel
allele(isolate7),ptaNovel allele(isolate5),* arcC: Novel allele(isolate5) were reported in our study.In
our study CC8 -ST2454 were identified from Karnal & Ambala.This study could help to identify
predominant clones and provide surveillance measures to decrease the incidence of subclinical mastitis
in buffaloes in Haryana.