Temporal trends and clonal diversity of penicillin non-susceptible pneumococci from meningitis cases from 1996 to 2012, in Salvador, Brazil.

Milena Soares Dos Santos,Joice Neves Reis,Leila Carvalho Campos,Ana Paula De Oliveria Menezes,Soraia Machado Cordeiro,Eliane Cunegundes Escobar,Josilene Borges Lima,Albert I Ko,Maria Da Glória S Carvalho,Mitermayer G Reis,Jailton Azevedo

doi:10.1186/s12879-015-1049-y

Abstract

BackgroundHospital-based surveillance for pneumococcal meningitis has been conducted since January 1996 in the city of Salvador, Brazil. The purpose of this study was to describe the temporal evolution of Penicillin Non-Susceptible Streptococcus pneumoniae (PNSSP) in regards to serotype distributions and clonal diversity recovered from meningitis cases over 17 years.MethodsBroth microdilution was used to identify pneumococcal isolates that were PNSSP (Minimum Inhibitory Concentration > 0.12 μg/ml). The annual incidence rate of meningitis cases was calculated. Serotyping was defined using multiplex polymerase chain reaction assays and quellung reaction. Genetic diversity of PNSSP isolates was assessed using both pulsed-field gel electrophoresis (PFGE) and Multilocus Sequence Typing (MLST) analyses.ResultsA total of 854cerebrospinal fluid (CSF) culture pneumococcal isolates were tested by broth microdilution method and serotyped. A total of 173 (20.3 %) were penicillin non-susceptible (PNSSP) (Minimum Inhibitory concentration ≥ 0.12 μg/ml). The annual incidence of meningitis cases declined from 1.65/100,000 population (1996) to 0.2/100,000 population in 2012 and the rate due to PNSSP declined 82 % over the 17-years of surveillance. PNSSP isolates were restricted to 13 serotypes, being the most common ones serotypes14 (45.1 %; 78/173), 23 F (19.1 %; 33/173), 6B (14.4 %; 25/173), 19 F (9.2 %; 16/173) and 19A (5.2 %; 9/173). Among the PNSSP isolates, 94 % had serotypes represented in the 10-valent conjugate vaccine (PCV10). The predominant serotype 14 clonal groups were identified as PFGE group A/multilocus sequence type 66 (ST66) [35.3 % (61/173)] and PFGE group GK/ST156 [4.6 % (8/173)], the latter one associated with high level resistance to penicillin and ceftriaxone.ConclusionsOur results show sustained reductions in pneumococcal meningitis cases in the Metropolitan region of Salvador from 1996 to 2012. This might reflect a beneficial impact of conjugate vaccines. Continued surveillance and further studies need to be conducted to better understanding on PCV10 vaccine impact.

Highlights

Hospital-based surveillance for pneumococcal meningitis has been conducted since January 1996 in the city of Salvador, Brazil
Surveillance for penicillin nonsusceptible pneumococcal meningitis A total of 917 patients with S. pneumoniae meningitis were consecutively identified at the surveillance hospital during 17 years of laboratory-based active surveillance
Considering that 489 patients resided within the Metropolitan Salvador, the annual incidence of pneumococcal meningitis declined from 1.65/100,000 population (1996) to 0.2/100,000 population in 2012

Summary

Introduction

Hospital-based surveillance for pneumococcal meningitis has been conducted since January 1996 in the city of Salvador, Brazil. The purpose of this study was to describe the temporal evolution of Penicillin Non-Susceptible Streptococcus pneumoniae (PNSSP) in regards to serotype distributions and clonal diversity recovered from meningitis cases over 17 years. It is an opportunistic pathogen that causes infections leading to otitis media, pneumonia, sepsis and meningitis [1]. Antibiotic resistance which has been shown to be associated with a limited spectrum of serotypes, commonly responsible for invasive disease, may have adverse impact on the epidemiology of pneumococcal disease [3]. Resistant pneumococci have been isolated in all continents. In several settings over 40 % of clinical isolates exhibit multidrug-resistance [4]

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