Molecular Characterization and Antimicrobial
Sensitivity of Pathogens from Sub-Clinical and Clinical Mastitis in
Eastern China
Javed Memon, Jam Kashif, Muhammad Yaqoob, Wang
Liping, Yongchun Yang and Fan Hongjie*
College of Veterinary Medicine,
Nanjing Agricultural University, Nanjing 210095 P.R China *Corresponding author:fhj@njau.edu.cn
Abstract
Prevalence of sub-clinical and clinical coliform
mastitis with antimicrobial sensitivity profile of various mastitis-causing
organisms was investigated. Milk samples collected from 299 cows infected with
clinical mastitis to evaluate the prevalence of coliform mastitis and 1660
quarters milk samples randomly collected from 415 lactating cows for detection
of subclinical mastitis (SCM) by Hangzhou Mastitis Test (HMT). SCM at quarters
and cow level was recorded to be 20.2 and 52.3%, respectively. Occurrence of SCM
in left rear quarter was high (26.7%). Statistical analysis of risk factors
showed, cows with 6-9 years of age (P=0.046; Odds ratio (OR), +1.414; 95% confidence interval
(CI)=1.006-1.988 and 60.7%), cows
with 4-7 calves (P=0.028; OR, +1.502;
95% CI=1.044-2.160 and 62.2%),
and cows in late stage of lactation (P=0.039;
OR, +1.947; 95% CI=1.023-3.702 and
68%), were more susceptible to SCM. All the 115 organisms from SCM
milk samples and 103 Escherichia coli
from CM samples were confirmed by PCR techniques. Minimum inhibitory
concentration (MIC) results revealed that
E. coli isolates were resistant to penicillin group (93-99%),
fluoroquinolones (40-74%), cephalosporins (54-66%), oxytetracycline (91%),
gentamycin (82%), SUL-TRM (88%) and were sensitive to florfenicol.
Staphylococcus aureus isolates were resistant to ampicillin (91%),
oxytetracycline (59%) and methicillin (29%).
Streptococcus agalactiae isolates were 8 to 15% resistant to used
antimicrobials. In conclusion, cows with SCM were reservoir of various bacterial
pathogens and high prevalence of E. coli
in clinical mastitis milk could be major complications for mastitis treatment
due to their multidrug resistance profile.