Case Report
Two and half year-old indigenous male bovine calf was brought to Veterinary Teaching Hospital, Bangladesh Agricultural University, Mymensingh having body weight 158 kg with the complaint of wound. Visual examination revealed the case of myiasis leading to wound. Dressing was performed, swab sample from wound before dressing was collected using sterile cotton bud both from outer and inner part of wound and transferred to nutrient broth for molecular study (Figure 1). The collected broth samples were incubation at 37ºC for 2 hours for enrichment and inoculated into selective media i.e. Mannitol salt agar (MSA) and MacConkey agar (MAC) and incubated at 37º C for overnight. Next day the growth of bacteria was observed and pure culture of each bacteria were obtained by repeated culture of single colony. The pure cultures of isolated bacteria were subjected to Gram´s staining for observation of bacterial morphology, arrangement and staining characteristics under light microscope at 10x magnification, as per the method described by Jaman et al. [9] Bacteria from pure culture subjected to DNA extraction by boiling method, as per described by Khalid et al. [10] and PCR was done using S. aureus specificnuc gene and MRSA specific mec A gene primers, with an expected protocol size 279 bp and 533 bp respectively. Forward and Reverse primers used to detect nuc gene and mec A gene were mentioned in Table 1.
On the basis of cultural characteristics and staining propertiesStaphylococcus aureus was identified from outer part of wound as on Mannitol Salt Agar (MSA), Staphylococcus aureus produce golden yellow colony and on Gram´s staining it shows Gram positive, smooth, convex, grape-like clusters (Figure 2 and Figure 3). On the basis of PCR, it was further confirmed that the isolated bacteria are Staphylococcus aureus and methicillin resistant staphylococcus aureus by nuc gene and mec A gene respectively. (Figure 4 and Figure 5)