Molecular Resistance Mechanisms of Macrolide-Resistant Invasive Streptococcus pneumoniae Isolates from Alaska, 1986 to 2010

Abstract

The rapid emergence of antibiotic-resistant pneumococcal strains has reduced treatment options. The aim of this study was to determine antimicrobial susceptibilities, serotype distributions, and molecular resistance mechanisms among macrolide-resistant invasive pneumococcal isolates in Alaska from 1986 to 2010. We identified cases of invasive pneumococcal disease in Alaska from 1986 to 2010 through statewide population-based laboratory surveillance. All invasive pneumococcal isolates submitted to the Arctic Investigations Program laboratory were confirmed by standard microbiological methods and serotyped by slide agglutination and the Quellung reaction. MICs were determined by the broth microdilution method, and macrolide-resistant genotypes were determined by multiplex PCR. Among 2,923 invasive pneumococcal isolates recovered from 1986 to 2010, 270 (9.2%) were nonsusceptible to erythromycin; 177 (66%) erythromycin-nonsusceptible isolates demonstrated coresistance to penicillin, and 167 (62%) were multidrug resistant. The most frequent serotypes among the macrolide-resistant isolates were serotypes 6B (23.3%), 14 (20.7%), 19A (16.7%), 9V (8.9%), 19F (6.3%), 6A (5.6%), and 23F (4.8%). mef and erm(B) genes were detected in 207 (77%) and 32 (12%) of the isolates, respectively. Nineteen (7%) of the erythromycin-nonsusceptible isolates contained both mef and erm(B) genotypes; 15 were of serotype 19A. There was significant year-to-year variation in the proportion of isolates that were nonsusceptible to erythromycin (P < 0.001). Macrolide resistance among pneumococcal isolates from Alaska is mediated predominantly by mef genes, and this has not changed significantly over time. However, there was a statistically significant increase in the proportion of isolates that possess both erm(B) and mef, primarily due to serotype 19A isolates.

Increase in the rate of azithromycin-resistant Streptococcus pneumoniae isolates carrying the erm(B) and mef(A) genes in Taiwan, 2006–2010

“…Our finding of increase in the rate of azithromycin-resistant S. pneumoniae isolates carrying the erm (B) and mef (A) genes from from 10% in 2006 to 25% in 2010 after the introduction of the pneumococcal conjugate vaccine in Taiwan. These findings are in line with a previously published report on the PROTEKT US surveillance study from 10% in 2000 1 to 16% in 2003 [ 21 ], the study in Alaska from 0% in 1986 to 21% in 2010 [ 8 ], and the study in Canada from 3% in 1998 to 19% in 2008 [ 22 ].…”

“…In this study, the majority of azithromycin-resistant isolates carrying both mef(A) and erm(B) genes was serotype 19 F (58/91; 64%), followed by19A (22/91; 24%) and is similar to a previous published report in Korea, 57% of carried both genes were serotype 19 F (44/77, 57%), followed by 19A (21/77, 30%)7.5%) [ 23 ]. However, the study in Alaska showed 79% of isolates carrying both genes was serotype 19A (15/19), followed by 19 F (3/19; 16%) [ 8 ].…”

“…In Finland and Germany, the most frequent macrolide resistance determinant carried was the mef gene [ 6 ],[ 7 ]. Macrolide resistance among pneumococcal isolates in Alaska recovered from 1986–2010 was also reported to be predominantly mediated by mef genes and this has not changed significantly over time [ 8 ]. However, the authors of the study reported a significant increase in the proportion of isolates that possess both erm(B) and mef(A), primarily among serotype 19A isolates.…”

Salvage microbiology: opportunities and challenges in the detection of bacterial pathogens following initiation of antimicrobial treatment

“…Multiplex PCR platforms have the capacity to identify pathogens such as pneumococcus, and detect the presence of antimicrobial resistance genes. [9] But recognizing the appropriate patient for screening or interrogation will require education. The platform that has achieved the most wide-spread acceptance in screening for MDROs is the Cepheid GenXpert ™ real-time PCR platform that has assays capable of screening for MRSA, VRE, and CRE.…”

Antibacterial Effect of Zinc Oxide Nanoparticles on Group A β-Hemolytic Streptococci with Macrolide Resistance Isolated from University Student Carriers in North of Iran

“…This single-stage resistance developed in higher concentrations of the drug is resulted by chromosomal mutation. Another type of resistance found in clinical samples is related to a change in the 23SrRNA from 50S ribosomal subunit (8). Most studies referred to the mef (A) gene as the dominant gene, which determines macrolide resistance in GABHS (9).…”