BACKGROUND AND OBJECTIVES:

Reports on extended-spectrum β-lactamases (ESBL) production by Enterobacteriaceae, and especially in Klebsiella pneumoniae, are few in Saudi Arabia. Therefore, we determined the prevalence of ESBL in K pneumoniae from Riyadh and characterized the predominant β-lactamase gene in these isolates.

METHODS:

A total of 400 K pneumoniae samples were isolated from two hospitals in Riyadh during 2007 and screened for production of ESBL using ESBL-E-strips and combined disk methods. PCR assay was used to detect blaTEM, blaSHV, and blaCTX-M genes.

RESULTS:

Phenotypic characterization identified a high ESBL rate of 55% of K pneumoniae isolates. ESBL-producing K pneumoniae were PCR positive for SHV, TEM and CTX-M β-lactamase genes with prevalences 97.3%, 84.1% and 34.1%, respectively. Within the CTX-M family, two groups of enzymes, CTX-M-1 and CTX-M-9-like genes were found with prevalences of 60% and 40%, respectively.

CONCLUSIONS:

This study confirms the high rate of ESBL in K pneumoniae clinical isolates in hospitals in Riyadh. This study demonstrates the worldwide spread of blaCTX-M genes. This first report of the presence of the blaCTX-M gene in clincial isolates in Saudi Arabia is evidence of the continuing worldwide spread of this gene.

Antimicrobial resistance in Streptococcus pneumoniae remains a serious concern worldwide, particularly in Asian countries, despite the introduction of heptavalent pneumococcal conjugate vaccine (PCV7). The Asian Network for Surveillance of Resistant Pathogens (ANSORP) performed a prospective surveillance study of 2,184 S. pneumoniae isolates collected from patients with pneumococcal infections from 60 hospitals in 11 Asian countries from 2008 to 2009. Among nonmeningeal isolates, the prevalence rate of penicillin-nonsusceptible pneumococci (MIC, ≥4 μg/ml) was 4.6% and penicillin resistance (MIC, ≥8 μg/ml) was extremely rare (0.7%). Resistance to erythromycin was very prevalent in the region (72.7%); the highest rates were in China (96.4%), Taiwan (84.9%), and Vietnam (80.7%). Multidrug resistance (MDR) was observed in 59.3% of isolates from Asian countries. Major serotypes were 19F (23.5%), 23F (10.0%), 19A (8.2%), 14 (7.3%), and 6B (7.3%). Overall, 52.5% of isolates showed PCV7 serotypes, ranging from 16.1% in Philippines to 75.1% in Vietnam. Serotypes 19A (8.2%), 3 (6.2%), and 6A (4.2%) were the most prominent non-PCV7 serotypes in the Asian region. Among isolates with serotype 19A, 86.0% and 79.8% showed erythromycin resistance and MDR, respectively. The most remarkable findings about the epidemiology of S. pneumoniae in Asian countries after the introduction of PCV7 were the high prevalence of macrolide resistance and MDR and distinctive increases in serotype 19A.