Isolation, Identification And Pcr Detection Of Methicillin Resistant Staphylococcus aureus (MRSA) In Cow Milk Samples From Perak
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Date
2016-09
Authors
Anamalai, Sanggari
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Abstract
Staphylococci colonize a diverse range of animals and human and this
association is normally harmless. Some strains of Staphylococcus have increased
ability to cause disease. Biochemical tests used to identify staphylococci are lengthy.
Furthermore, commercially available panels do not allow a reliable distinction
between different coagulase-negative staphylococci (CNS). As an alternative, the
development of a PCR based technique will be useful to identify pathogenic strains
of Staphylococcus. In this study Staphylococcus samples were isolated from cow
milk and characterized using phenotypical methods. Two hundred and twenty five
isolates identified from four different collection centers in Taiping, Tapah, Parit and
Sungai Siput were tested. S. aureus strains were characterized by beta hemolysis,
Gram stain, coagulase test, catalase test, mannitol fermentation and maltose
fermentation. The positive samples were further investigated by antibiotic
susceptibility test by using 1μg oxacillin disc. Result of antibiotic susceptibility test
confirmed that 19 S.aureus isolates (12.41%) were found to be methicillin resistant
S. aureus (MRSA), while 1 isolate (0.65%) showed intermediate resistance and 133
(86.93%) as methicillin sensitive S. aureus (MSSA). In addition, detection of MRSA
in milk was performed using PCR to confirm the presence of a 686 bp femA fragment
and a 310 bp mecA fragment which are essential in MRSA identification. Ten
samples were positive for the mecA gene whereas three samples did not possess the
femA gene. Two of them were classified as Coagulase Negative S. aureus. One was
categorised as non-Staphylococcus isolate since it was negative for coagulase and
catalase test. One strain was susceptible in oxacillin disk diffusion test but possesses
mecA and femA genes. This may be because the isolate is heteroresistant. Data from
this study indicated that phenotypic method alone was not adequate for identifying
MRSA. This study will improve the reliability of detection for Staphylococcus using
PCR to complement existing biochemical tests and will be very useful for rapid
detection of pathogenic species of S. aureus and MRSA.
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Keywords
Identification And Pcr Detection Of Methicillin Resistant Staphylococcus aureus (MRSA) , In Cow Milk Samples From Perak.