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Serotype Distribution and Susceptibility to Penicillin and Erythromycin Among Noninvasive or Colonization Isolates of Streptococcus pneumoniae in Northern Japan: A Cross-Sectional Study in the Pre-PCV7 Routine Immunization Period

Microbial drug resistance (Larchmont, N.Y.) (Impact Factor: 2.49). 04/2014; 20(5). DOI: 10.1089/mdr.2013.0196
Source: PubMed

ABSTRACT

Distribution of serotypes, prevalence of resistance to penicillin and/or erythromycin (EM), and its genetic traits were analyzed for a total of 1,061 noninvasive or colonization isolates of Streptococcus pneumoniae (998 and 61 isolates from children and adults, respectively) in Hokkaido, northern main island of Japan, in the year 2011, the pre-PCV7 routine immunization period. Serotype deduction was performed by sequential multiplex polymerase chain reaction (PCR), employing mutagenic PCR-restriction fragment length polymorphism for discrimination of 6A/C and 6B/D. Unaltered three PBP genes and macrolide resistance genes erm(B) and mef(A/E) were detected by multiplex PCR. Among isolates from children, 25 serotypes, including the prevalent types 6B (17.5%), 19F (15.6%), 23F (12.2%), and 6C (11.6%), were identified, revealing the PCV7 and PCV13 coverage rates as 48.2% and 60.3%, respectively, while serotype 3 was the most frequent (19.0%) among isolates from adults. Most of the pediatric isolates (96.8%) exhibited resistance to EM (minimum inhibitory concentration [MIC], ≥1 μg/ml), with a higher prevalence of erm(B) (67.2%) than mef(A/E) (39.7%). erm(B) was associated with high-level EM resistance (MIC, ≥128 μg/ml) and distributed at high detection rates to major serotypes 23F (85.2%) and 6B (85.1%), as well as minor serotypes 3, 10A, 14, 15B, 15C, 19A, and 23A (>90%). While penicillin-resistant S. pneumoniae (PRSP) (penicillin G-MIC, 2-3 μg/ml) was detected in 7.8% of isolates from children, the most common PBP gene genotype was gPRSP (three altered genes pbp1a, 2x, and 2b; 38.3%), which was detected at higher rates (>60%) in the dominant serotypes 23F, 6B, and 19F, and minor serotypes 6D and 15A. Dominant serotypes in the S. pneumoniae isolates were generally similar to those reported for invasive strains, despite lower coverage rates by PCV7/13. The importance of further surveillance on incidence and drug resistance in the post-PCV7 period was suggested for non-PCV7/13 serotypes 6C, 6D, 10A, 15A, 15B, 15C, 23A, and 35B.

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    • "The macrolide resistance genes erm(B) and mef(A/E) were detected by M-PCR using primers described previously [12] [13]. Serotypes 15B and 15C were identified by PCR and direct sequencing of partial wciZ as previously described [8], after detection of 15B/C by SM-PCR. "
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    ABSTRACT: In Japan, 7-valent pneumococcal conjugate vaccine (PCV7) was introduced as routine immunization program in April 2013, and replaced by 13-valent pneumococcal conjugate vaccine (PCV13) in November 2013. Distribution of serotypes and macrolide resistance genotypes was investigated for a total of 1097 (975, children; 122, adults) and 960 (873, children; 87, adults) clinical isolates of S. pneumoniae from noninvasive infections in Hokkaido, northern main island of Japan, in the PCV7- and PCV13-routine immunization periods (Apr.-Oct. 2013 and Nov. 2013-Nov. 2014, respectively). Serotype was determined by sequential multiplex PCR and additional genetic analyses. Macrolide resistance genes erm(B) and mef(A/E) were detected by multiplex PCR. Although the most prevalent serotypes in children were 23A and 6C in the PCV7 period, after replacement with PCV13, 19A became the most common followed by 6C, 15A, and 23A. Among adults, serotype 3 was consistently most frequent throughout the study periods. Compared with previous study in the pre-PCV7 routine immunization period, PCV7 serotypes decreased from 48.3% to 3.3% in the PCV13 period among children, while the rates of non-PCV13 serotypes (particularly 15A, 23A, 11A, 10A, and 35B) increased from 39.7% to 75.1%, (p<0.001). In the PCV13 period, erm(B), mef(A/E), and both of these genes were detected in 75.8%, 31.6%, and 11.3% of all isolates, respectively. Serotype 19A accounted for 76.9% of the isolates with both the macrolide resistance genes, and emerging non-PCV13 serotypes 15A, 15C, and 23A mostly harboured erm(B).
    Full-text · Article · Nov 2015
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    ABSTRACT: Serogroup 6 of Streptococcus pneumoniae contains four established serotypes (6A-6D). Recently, putative serotype 6E (genotype 6E) was proposed as a novel type, which is cross-reactive with 6B-specific antiserum, but its capsular polysaccharide synthesis (cps) locus is genetically distinct from those of serotypes 6A and 6B. In the present study, prevalence of genotype 6E was analyzed by a newly designed multiplex polymerase chain reaction (PCR) for noninvasive or colonizing S. pneumoniae isolates in northern Japan assigned to serogroup 6 in our previous study by the sequential multiplex PCR developed by Pai et al. Among the isolates previously assigned to 6A and 6B, 2.2% (1/45) and 77.3% (140/181) of isolates, respectively, were revealed to have cps genes of genotype 6E. Eight 6E isolates selected for further analysis were found to have identical or highly similar sequences of cps genes (wzg, wzh, wze, wciN, wciP, and wzy) to those of strains previously reported as putative serotype 6E, and all the isolates were classified into sequence type 90 (ST90). Reanalysis of genetic traits on penicillin and macrolide resistance clarified significantly higher rates of three pbp mutations (gPRSP) and ermB in genotype 6E than in serotypes 6A and 6B. These findings suggested a need for detection of genotype 6E in the surveillance of S. pneumoniae serotypes.
    No preview · Article · Oct 2014 · Microbial drug resistance (Larchmont, N.Y.)
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    ABSTRACT: Background: Streptococcus pneumoniae, which cause noninvasive pneumococcal diseases, severely impair children's health. This study analyzed serotype distribution and antimicrobial resistance of S. pneumoniae from January 2012 to December 2012 in a Children's Hospital, Shanghai. Methods: A total of 328 pneumococcal isolates were serotyped by multiplex sequential PCR and/or capsule-quellung reaction. The minimum inhibitory concentrations for 11 antimicrobial agents were determined by broth microdilution method. Results: Among 328 strains, 19F (36.3%), 19A (13.4%), 6A (11.9%), 23F (11.0%), 14 (5.8%), 6B (5.2%), and 15B/C (4.3%) were the most common serotypes. The coverage rates of 7-, 10-, and 13-valent conjugate vaccines (PCV7, PCV10, and PCV13) were 58.2%, 58.2%, and 84.1%, respectively. Out of the isolates, 26 (7.9%) strains were penicillin resistant. Most of the strains displayed high resistance rate to macrolides (98.5% to erythromycin, 97.9% to azithromycin, and 97.0% to clindamycin). Conclusions: The potential coverage of PCV13 is higher than PCV7 and PCV10 because of the emergence of 19A and there should be long-term and systematic surveillance for non-vaccine serotypes.
    Preview · Article · Jan 2015 · Brazilian Journal of Infectious Diseases