Rapid Consumption of Vancomycin in the Presence of Beta-Lactam Antibiotics Causes Beta-Lactam Antibiotic-Induced Vancomycin-Resistance in Methicillin-resistant Staphylococcus aureus

order to predict the efficacy of the vaccine in the Malaysian population. Methods: A total of 217 strains of S. pneumoniae obtained from invasive (blood, CSF, pleural fluid) and non-invasive sites (respiratory sites) of both pediatric and adult patients were serotyped by the method of Pai et al (2006). Strains were identified by standard methods and their antibiotic resistance profile determined by agar dilution method (PEN, ERY, CRO, CTX, CXM, CIP, GAT, MOX, LVX) and disk diffusion (PEN, ERY, CRO, CXM, AMC, AMP, VAN, SXT, CL, CN10, DA, OX, CIP). Seven different multiplex PCRs were used to determine the following serotypes/serogroups: 1, 2, 3, 4, 5, 8, 13, 14, 20, 21, 31, 34, 37, 38, 39, 40, 44, 46, 6A, 7A, 7B, 7C, 7F, 9A, 9N, 9L, 9L, 10A, 10F, 11A, 11D, 11F, 12A, 12B, 12F, 15A, 15B, 15C, 15F, 16A, 16F, 17F, 33A,35B, 35F, 35A, 35C, and 47F. The cps operon was used as the internal positive control. Results: Of the 217 strains, there were 22.6% PRSP, 27.7% PISP and 49.8% PSSP strains based on their susceptibility to penicillin. Serotypes detected were the 19F, 18C, 15B/C, 23F, 6A/B, 10A, 12A/F, 3, 14, 11A/D, 34, 19A, 16F, 35F/47F, and 7F/A. The most predominant serotype was 19F and it was also predominant in isolates obtained from invasive sites. Serotype 19F and 23F were observed to be common among the PRSP strains, with 35/49 strains serotyped as 19F while 13/49 strains were serotyped as 23F. Only one PRSP strain was serotyped as 34. Serotype 19F was also predominant among the PISP strains. Other serotypes detected among the PISP strains were 6A/B, 11A/D, 23F and 14. However, the distribution of these serotypes were rare. The PSSP strains showed to have other serotypes such as 18C, 15B/C, 6A/B, 10A, 19A, 3, 14, 16F, & 7B/C, 7F and 35F/47F. The distribution of serotype 19F and 23F was rare among this group of isolates. Conclusion: In conclusion, we observe serotype 19F and 23F to be prevalent among the penicillin resistant strains, which has been included in the 7-valent conjugate vaccine. Therefore, the efficacy of this vaccine should be effective in our population. However, it is not possible to predict serotypes that might become predominant in the future.