Surveillance
Penicillin resistance and serotypes/serogroups of Streptococcus pneumoniae in nasopharyngeal carrier children younger than 2 years in Lima, Peru

https://doi.org/10.1016/j.diagmicrobio.2004.12.014Get rights and content

Abstract

The purpose of this study was to determine the carriage rate, susceptibility pattern, and serotype distribution of Streptococcus pneumoniae in the nasopharynx of children younger than 2 years old in Lima, Peru. A total of 666 children were evaluated during 3 periods, 1997, 2001, and 2003. The overall pneumococcal carrier rate was 41%. Reduced susceptibility to penicillin was found in 5% (4/75) of isolates in 1997, 20% (15/75) in 2001, and 37% (40/109) in 2003. Reduced susceptibility to ceftriaxone was found in 12% of isolates in 2003. Serogroups 6, 19, 23, 15, and 14 accounted for 68% of all the isolates and for 81% of the penicillin-nonsusceptible strains. Only 65% of the isolated strains had serogroups found in the 7-valent conjugate pneumococcal vaccine. This highlights the importance of regional surveillance studies for effective vaccine strategies and treatment protocols.

Introduction

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, particularly in young children, patients with chronic diseases, the elderly, and immunocompromised individuals of all ages. Globally, approximately 1.2 million deaths due to pneumococcal pneumonia and meningitis are believed to occur among young children every year, mostly in developing countries (WHO, 1996).

Antibiotic-resistant S. pneumoniae has become an increasing clinical and public health problem around the world. Levels of penicillin resistance vary geographically, as well as the serotypes. There are more than 90 pneumococcal serotypes, but less than a dozen are responsible for most of infections in children. Regional and local knowledge of the distribution of capsular serotypes and antibiotics susceptibility of pneumococci is essential for the development of effective vaccine strategies and treatment protocols. In Peru, there are few studies on the susceptibility and serotype distribution of pneumococci and there are no prospective studies from a single location over time (Fukuda et al., 1996, Morales et al., 2001, Cullotta et al., 2002).

The purpose of this study was to determine the carriage rate, susceptibility pattern, and serotype distribution of S. pneumoniae in nasopharyngeal carrier children younger than 2 years old in the Pediatric Outpatient Clinic at Hospital Nacional Cayetano Heredia in Lima, Peru, at 3 time intervals (1997, 2001, and 2003), to compare the susceptibility over time, and to determine associated factors for carriage of penicillin-nonsusceptible strains.

Section snippets

Study population

Nasopharyngeal cultures were obtained from children at the Pediatric Outpatient Clinic of Hospital Nacional Cayetano Heredia during 3 periods: September 1996 to March 1997, March 2001 to September 2001, and June 2003 to December 2003. This hospital is the major medical facility serving the low socioeconomic communities of the northern part of Lima city, a population of almost 3 million inhabitants.

Children 6 to 24 months of age who attended the clinic for a routine well-child visit or sick

Study population characteristics

Nasopharyngeal cultures were obtained from 666 children (170 in the first period, 226 in the second period, and 270 in the third period). Children were between 6 and 24 months of age (median 10 months); 50% were girls. More children from the third period attended day care and were from households with ≥3 children. The use of antibiotics was more common in the second period (data not available for the third period) (Table 1). The most commonly used antibiotics were amoxicillin (50%) and TMP/SMX

Discussion

The most important finding of this study is the marked increase in penicillin resistance over the studied period (5% to 37%). In part, this can be explained by the small but higher proportion of patients that attended day care and higher proportion of patients from households with larger number of children, during the third period of the study. This probably reflects the socioeconomic trend in this population (more mothers working, more day-care attendance, and more crowded living conditions).

Acknowledgments

This work was funded in part by a grant from Consejo Nacional de Ciencia y Tecnología (CONCYTEC, Peru) and by an award from Fondo de Apoyo al Investigador Farmaindustria (FAIF 2000, Peru) and supported by the following Peruvian laboratories: Roche, Hoechst Marion Roussel, Eli Lilly, and Becton Dickinson. The authors thank Dr Thomas Cleary for his helpful suggestions and review of the manuscript, Dr Kathleen Kennedy for her help with the data analysis, and Susan Kirby for her secretarial support.

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