Serotypes and antibiotic susceptibility of Streptococcus pneumoniae isolates causative of invasive diseases in Mexican children

José Luis Arredondo-García,Carlos F Amabile-Cuevas,Ernesto Calderón,Gabriela Echániz-Aviles,Araceli Soto-Noguerón,Patricia Arzate

doi:10.3855/jidc.1348

Abstract

Streptococcus pneumoniae is a worldwide leading cause of morbidity and mortality, while susceptibility towards penicillin and macrolides can be less than 50% in many regions. A total of 150 isolates of S. pneumoniae causative of invasive diseases in children were characterized, of which 24.6% had a fatal outcome. The most prevalent serotypes were 19F, 6B, 23F and 14. Resistance to penicillin, erythromycin (mostly of macrolide-lincosamide-streptogramin resistance phenotype) or trimethoprim-sulfamethoxazole was found in more than 40% of the isolates, but no resistance phenotype appeared linked to lethality. Serotype 3 isolates, which were seldom resistant, had a twofold lethality rate compared to the total sample. Serotyping could provide a better outcome-predicting tool than susceptibility testing. The seven-valent vaccine does not include the most prevalent serotypes found in Mexico.

Highlights

Streptococcus pneumoniae is a worldwide leading cause of morbidity and mortality, while susceptibility towards penicillin and macrolides can be less than 50% in many regions
The incidence of penicillin and macrolide pneumococcal resistance has increased so substantially that many regions of the world report less than 50% of clinical isolates as being fully susceptible
Pneumococcal serotypes that cause invasive infections in Mexican children are not precisely those included in the seven-valent conjugate vaccine

Summary

Introduction

Streptococcus pneumoniae (Spn) is a leading cause of morbidity and mortality associated with infectious diseases worldwide. Local and systemic infections caused by Spn include otitis media and sinusitis as less serious but very common illnesses, as well as bacteremia, pneumonia, sepsis and meningitis [1], all serious bacterial infections. The use of a seven-valent pneumococcal conjugate vaccine (including capsular antigens from serotypes 4, 6B, 9V, 14, 18C, 19F and 23F) has reduced the prevalence of invasive pneumococcal disease [2]; this vaccine is not widely used in Mexico. The clinical course of pneumococcal invasive disease (PID) was correlated with serotype/serogroup and antimicrobial resistance patterns in a large pediatric population between 2002 and 2005

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