Infect Chemother.  2018 Dec;50(4):328-339. 10.3947/ic.2018.50.4.328.

The Evolving Epidemiology of Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Strains Isolated from Adults in Crete, Greece, 2009–2016

Affiliations
  • 1Department of Clinical Microbiology and Microbial Pathogenesis, University Hospital of Heraklion, Crete, Greece. sofiamaraki@yahoo.gr
  • 2University of Crete Medical School, Heraklion, Crete, Greece.
  • 3Infectious Diseases Unit, University Hospital of Heraklion and University of Crete Medical School, Heraklion, Crete, Greece.

Abstract

BACKGROUND
Pneumococcal disease is a major cause of morbidity and mortality worldwide, especially in patients with comorbidities and advanced age. This study evaluated trends in epidemiology of adult pneumococcal disease in Crete, Greece, by identifying serotype distribution and antimicrobial resistance of consecutive Streptococcus pneumoniae strains isolated from adults during an 8-year time period (2009-2016) and the indirect effect of the infant pneumococcal higher-valent conjugate vaccines 10-valent pneumococcal conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13).
MATERIALS AND METHODS
Antimicrobial susceptibility was performed by E-test and serotyping by Quellung reaction. Multidrug resistance (MDR) was defined as non-susceptibility to penicillin (PNSP) combined with resistance to ≥2 non-β-lactam antimicrobials.
RESULTS
A total of 135 S. pneumoniae strains were isolated from adults during the study period. Twenty-one serotypes were identified with 17F, 15A, 3, 19A, and 11A, being the most common. The coverage rates of PCV10, and PCV13 were 17.8% and 37.8%, respectively. PCV13 serotypes decreased significantly from 68.4% in 2009 to 8.3% in 2016 (P = 0.002). The most important emerging non-PCV13 serotypes were 17F, 15A, and 11A, with 15A being strongly associated with antimicrobial resistance and MDR. Among all study isolates, penicillin-resistant and MDR strains represented 7.4% and 14.1%, respectively. Predominant PNSP serotypes were 19A (21.7%), 11A (17.4%), and 15A (17.4%). Erythromycin, clindamycin, tetracycline, trimethoprim-sulfamethoxazole, and levofloxacin resistant rates were 30.4%, 15.6%, 16.3%, 16.3%, and 1.5%, respectively.
CONCLUSION
Although pneumococcal disease continues to be a health burden in adults in Crete, our study reveals a herd protection effect of the infant pneumococcal higher-valent conjugate vaccination. Surveillance of changes in serotype distribution and antimicrobial resistance among pneumococcal isolates are necessary to guide optimal prevention and treatment strategies.

Keyword

Streptococcus pneumoniae; Adults; Serotyping; Antimicrobial resistance; Pneumococcal conjugate vaccine

MeSH Terms

Adult*
Clindamycin
Comorbidity
Drug Resistance, Multiple
Epidemiology*
Erythromycin
Greece*
Humans
Infant
Levofloxacin
Mortality
Penicillins
Pneumonia
Serogroup*
Serotyping
Streptococcus pneumoniae*
Streptococcus*
Tetracycline
Trimethoprim, Sulfamethoxazole Drug Combination
Vaccination
Vaccines, Conjugate
Clindamycin
Erythromycin
Penicillins
Tetracycline
Trimethoprim, Sulfamethoxazole Drug Combination
Vaccines, Conjugate
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