Phenotypic Characteristics of Vancomycin-Non-Susceptible Staphylococcus aureus
| Author | Auttawit Sirichoat | en |
| Author | Sujintana Wongthong | en |
| Author | Ratdawan Kanyota | en |
| Author | Ratree Tavichakorntrakool | en |
| Author | Aroonwadee Chanawong | en |
| Author | Jariya Umka Welbat | en |
| Author | Aroonlug Lulitanond | en |
| Issued Date | 2016-01-01 | en |
| Abstract | Background: Staphylococcus aureus, with reduced vancomycin susceptibility, is probably under the regulation of several genes and various express phenotypes. Objectives: This study aimed to investigate the phenotypic differences between vancomycin-susceptible S. aureus (VSSA), vancomycin-intermediate S. aureus (VISA), and heterogeneous VISA (hVISA) isolates. Materials and Methods: A total of 130 methicillin-resistant S. aureus (MRSA) isolates were studied, including 49 VSSA, 28 hVISA, and 5 VISA isolates from blood cultures and 48 isolates (two VSSA, six hVISA, and 40 VISA) derived in vitro (laboratory-induced/sub-passaged). Their phenotypes were examined using a coagulase tube test, colony spreading on soft agar, and urease activity. The SCCmec and agr typing were performed using multiplex PCR. Results: Most of the MRSA isolates were SCCmec III-agr I (84.5%), followed by SCCmec II-agr II (11.8%). The average plasma coagulation time of vancomycin-non-susceptible isolates was longer than that of the susceptible isolates (12 vs. 2.6 hours). Four hVISA (P = 0.023) and nine VISA (P < 0.001) isolates yielded a negative coagulase test after 24-hour incubation. The percentage of VSSA isolates showing non-spreading colonies (accessory gene regulator (agr) dysfunction) was significantly lower than in the VISA group (P = 0.013), but no significant difference was found between VSSA and hVISA. The VISA group showed higher urease activity than that of the VSSA and hVISA groups (P = 0.002). Conclusions: There were diverse phenotypic changes among vancomycin-non-susceptible S. aureus isolates. This may be due to the variety of related regulatory systems. The diversity of phenotypic expression may result in its misidentification in routine laboratory checks. | en |
| DOI | https://doi.org/10.5812/jjm.26069 | en |
| Keyword | Coagulase | en |
| Keyword | Urease | en |
| Keyword | Vancomycin | en |
| Keyword | Methicillin-Resistant <i>Staphylococcus aureus</i> | en |
| Publisher | Brieflands | en |
| Title | Phenotypic Characteristics of Vancomycin-Non-Susceptible Staphylococcus aureus | en |
| Type | Research Article | en |