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Methicillin-resistant Staphylococcus aureus remains a global problem. The emergence of reduced susceptibility to Vancomycin in MRSA strains, leads to treatment failure and prolonged hospital stay. Therefore, we aimed to determine the strains with reduced susceptibility among MRSA clinical isolates. S. aureus isolates were collected from identified clinical samples. Antibiotic susceptibility was tested using the Kirby-Bauer method. MRSA strains were confirmed using PCR for mecA gene and subjected to the Epsilometer test (Etest®) for determination of Vancomycin minimum inhibitory concentration (MIC). Isolates with intermediate or reduced susceptibility were subjected to broth microdilution (BMD) and further confirmed by population analysis-area under curve (PAP-AUC) testing. Disc diffusion tests showed that all isolates (n = 105; 100%) were susceptible to Rifampicin, followed by Trimethoprim/Sulfamethoxazole. Meanwhile, a high resistance rate was demonstrated against Penicillin (n = 93; 88.6%). Among all isolates, only 26.0% (n = 27) were MRSA. According to the Vancomycin MIC value by Etest®, only two strains (A3, A106) had intermediate susceptibility, and one strain (A30) had reduced susceptibility to Vancomycin (MIC 3 μg/mL). No susceptibility to Vancomycin was identified among strains using the BMD method. According to the PAP-AUC method, it was confirmed that strain A3 was a heterogeneous VISA strain. Vancomycin Etest®, is a reliable screening test for VISA detection. Vancomycin BMD result was not in agreement with the Vancomycin Etest® result. PAP-AUC, the gold standard test used to detect Vancomycin resistance, should be conducted whenever possible for further confirmation and epidemiological record.

Group B Streptococcus (GBS) is a leading cause of various infectious diseases among humans and fish. However, the likelihood of GBS interspecies transmission that lead to potential zoonotic problem is less investigated. This study determined the antimicrobial susceptibility, serotype, virulence and pili genes, and sequence type (ST) of GBS isolated from humans and cultured tilapia in Malaysia. We report an unusual detection of the fish-adapted ST283 in human GBS isolates. Both ST283 obtained from humans and fish had several phenotypical and genotypic characteristics in common, including virulence and pilus genes as well as antimicrobial susceptibility, illustrating the value of monitoring GBS within the One Health scope. The study sheds light on the evolution of the GBS and provides new evidence for the potential interspecies transmission by identifying two human GBS isolates belonging to the variant common in fish hosts.