Abstract
Aim:This study was conducted to determine the occurrence of methicillin-sensitive and Staphylococcus aureus (MSSA) methicillin-resistant S. aureus (MRSA) from bovine mastitis and to characterize them with respect to antibiotic resistance gene mecA.Materials and Methods:A total of 160 mastitic milk samples were screened for the presence of S. aureus. The presumptive positive isolates were confirmed using nuc and 23S rRNA gene-based polymerase chain reaction. All the confirmed isolates were subjected to in vitro antibiogram using a number of antibiotics. Isolates which showed resistance against methicillin were characterized for the presence of mecA gene.Results:Out of the total 160 milk samples, 36 (22.5%) samples yielded S. aureus. The in vitro antibiogram revealed that 16.6% S. aureus isolates were resistant to all antibiotics screened for and 5.5% isolates were sensitive to all of them. Furthermore, the study found 94.4%, 83.3%, 77.7%, 66.6%, 50%, and 27.7% of S. aureus isolates resistant to penicillin, ampicillin, amoxicillin-sulbactam, enrofloxacin, ceftriaxone, and methicillin, respectively. Out of the 36 S. aureus isolates, only 6 (16.6%) isolates were confirmed as MRSA while rest were MSSA.Conclusion:The higher occurrence of S. aureus-mediated mastitis was concluded due to improper hygienic and poor farm management. The multiple drug resistance reveals the indiscriminate use of drugs and presence of methicillin resistance gene determinant is an alarming situation as such infections are difficult to treat.
Highlights
Staphylococcus aureus is a Gram-positive coccal bacterium found commonly as commensal on skin and mucous membrane of upper respiratory and lower urogenital tract of humans and various animal species [1,2]
S. aureus is the most prevalent and contagious pathogen that is found in 30-40% of all mastitic cases and 80% of subclinical bovine mastitis which may result in about 35 billion US dollar annual losses worldwide [4,5]
Lane M: 100 bp ladder, Lane 1: Positive control of S. aureus, Lane 2: Negative control having distilled water as template, Lane 3, 4, 6: Isolate from mastitic milk samples positive for S. aureus indicated by 270 bp band, Lane 5: Isolate from mastitic milk samples negative for S. aureus
Summary
Staphylococcus aureus is a Gram-positive coccal bacterium found commonly as commensal on skin and mucous membrane of upper respiratory and lower urogenital tract of humans and various animal species [1,2]. It has an ability to colonize and infect a variety of host species, including humans, farm and companion animals and wildlife. It is a primary and most lethal agent because it causes chronic and deep infections in the mammary glands that is extremely difficult to be cured [3]. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated
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