Changing epidemiology of pediatric Streptococcus pneumoniae isolates before vaccine introduction in Casablanca (Morocco).

The objective of this study was to describe the evolution over time of serotypes and antimicrobial resistance of Streptococcus pneumoniae isolates responsible for invasive pneumococcal disease (IPD) in children ≤5 years in Casablanca (Morocco), before vaccine introduction. Isolates recovered from cases of IPD in children ≤5 years during two study periods (1994-2001 and 2006-2010) were compared in terms of serotypes and antimicrobial susceptibility. Serogrouping was done using Pneumotest Kit and serotyping was done by the Quellung capsular swelling. Antibiotic susceptibility pattern was determined by Etest method. The theoretical coverages of the 7-, 10- and 13-valent pneumococcal vaccines were determined. A total of 85 and 102 isolates were studied for the two periods, respectively. During the first period, the most prevalent serogroups/serotypes were 5, 7, 1, 14, 6, 23, 19, 2, 15 and 18, whereas during the second study period, the most frequent were 19, 14, 6, 23, 5, 1 and 18. From 2006 to 2010, serotype 19A accounted for 7.8% of the isolates, whereas serogroups 33 and 22 were rarely isolated (1% each). Assuming cross protection among serogroups, the respective coverage rates for the first vs. second periods reached 40% vs. 53.9% for PCV7, 74.1% vs. 71.6% for PCV10 and 75.3% vs. 82.4% for PCV13. The prevalence of penicillin-nonsusceptibility increased (22.4% vs. 48.5%) as well as the levels of penicillin-resistance (5.9% vs. 15.8%). Penicillin-nonsusceptibility was relatively low across both study periods in serogroups 7, 15, 1 and 5, whereas it was high in serogroups 14, 19 and 23. In conclusion, serotype fluctuations and increases in antibiotic resistance of S. pneumoniae occurred in Casablanca before vaccine introduction. Both of these variations are probably linked to the increase in antibiotic use that has occurred in Casablanca over time. There is a need for a continuous surveillance to assess the vaccine formulations, monitor vaccine impact and to guide treatment recommendations.

Elmdaghri N ，Benbachir M ，Belabbes H ，Zaki B ，Benzaid H ... -  《-》

Impact of pneumococcal conjugate vaccines on burden of invasive pneumococcal disease and serotype distribution of Streptococcus pneumoniae isolates: an overview from Kuwait.

Diseases caused by Streptococcus pneumoniae are a major worldwide public health problem. The seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in Kuwait in August 2006 and the 13-valent vaccine, PCV13, in August 2010, for children aged <2 years, with catch-up programs for those from 2 to 5 years. The objective of this study was to evaluate the impact of vaccination on vaccine and non-vaccine serotype distribution in invasive and noninvasive S. pneumoniae isolates obtained in Kuwait from August 2006 through December 2011, as compared with previously published data. The susceptibility of all the isolates to penicillin was also evaluated. The study included all cases of noninvasive and invasive pneumococcal diseases (IPD) in children and adults among all age groups during this period. All isolates were serotyped using the Quellung reaction antisera and their susceptibility to penicillin was determined using the E test method. A total of 395 pneumococcal isolates were included in the study. After vaccine introduction, 23% of isolates were from children ≤5 years of age and 49% of cases in this age group were invasive, while 46% of isolates were from adults >50 years of age and 27% of cases in this age group were invasive. Two of 13 cerebrospinal fluid isolates and only one of 266 respiratory isolates obtained were penicillin resistant. For the post-vaccine period, the predominant serotypes in children ≤5 years were 19F, 19A, 6A, 8 and 15B for invasive isolates and 19F and 23F for noninvasive isolates and the predominant serotypes in adults >50 years of age were 14, 3, 1, 19F and 8 for invasive isolates and 19F, 23F, 6B, 14 and 19A for noninvasive isolates. Among children <2 years of age, coverage with PCV7, PCV10, and PCV13 was 34.6%, 38.5% and 61.5%, respectively, in the period post-vaccine introduction. Among children 2-5 years of age, corresponding coverage rates were 42.1%, 47.4% and 63.1%, respectively. A similar trend was noticed in adults, with coverage rates in the 51- to 65-years age group of 45.8%, 62.5% and 70.8% respectively. Compared with previously published findings, from the period prior to vaccine introduction, this represented an increased incidence in some non-PCV7 serotypes that are included in PCV13 (serotypes 1, 6A, and 3). In conclusion, with the emergence of new pneumococcal serotypes, broader vaccine coverage will aid in the prevention of IPD in children.

Mokaddas E ，Albert MJ 《-》

Antibiotic resistance and serotype distribution of invasive pneumococcal diseases before and after introduction of pneumococcal conjugate vaccine in the Kingdom of Saudi Arabia (KSA).

Streptococcus pneumoniae is one of the most common bacterial causes of morbidity and mortality worldwide, causing life threatening infections such as meningitis, pneumonia and febrile bacteremia, particular among young children. The severity and frequency of S. pneumoniae infection and emergence of drug-resistant isolates have highlighted the need for prevention of invasive pneumococcal disease (IPD) as the best method for controlling disease; to better achieve this, more information is needed about serotype distribution and patterns of antibiotic resistance in children in the Kingdom of Saudi Arabia (KSA). Cases of pneumococcal infections in children aged <5 years, recorded in hospitals throughout KSA from 2005 to 2010 were reviewed for serotyping and for antibiotic susceptibility. This covers the time period just before limited introduction of 7-valent pneumococcal conjugate vaccine (PCV7) in 2006, to its introduction into the national immunization program in 2008, until right after a switch to PCV13 in 2010. Case definition required isolation of S. pneumoniae from blood, cerebrospinal fluid, or any sterile biological fluid. Isolates from 311 eligible cases were collected from different regions across KSA, 250 from blood and 61 from cerebrospinal fluid. The most frequently isolated IPD serotypes were 23F, 19F, 6B, 5 and 1. Over the course of the study, there was significant rise of serotype 19A (covered by PCV13 but not PCV7), which accounted for 20% of isolates of IPD in Western and 5% in Central regions in the last 2 years in KSA. There was a notable decrease in serotype 18C over this period, one of the PCV7 serotypes. Serotype coverage for PCV7, PCV10, PCV13 in children <5 years was 53%, 80%, and 91%, respectively across the Kingdom from 2005 to 2010. A total of 66% of IPD isolates were penicillin-resistant, and 62% were erythromycin-resistant. Continued surveillance is critical to measure the emerging of new serotypes and antibiotic resistance strain, and the potential impact of new PCVs. PCV13, recently introduced into the national immunization schedule in place of PCV7, provides the widest coverage among all IPD serotypes across KSA.

Shibl AM ，Memish ZA ，Al-Kattan KM 《-》

Non-susceptibility trends and serotype coverage by conjugate pneumococcal vaccines in a Tunisian paediatric population: a 10-year study.

Streptococcus pneumoniae is one of the major causative agents of invasive infectious disease in children <5 years old globally. The aim of this study was to analyze the antimicrobial resistance and the serotype distribution of S. pneumoniae isolates from the paediatric population in Tunisia and to specify the serotypes coverage by the conjugate pneumococcal vaccines. Antimicrobial susceptibility was determined by the disk diffusion method. Minimal inhibitory concentrations of beta-lactams were determined using the E test method (AB BIODISK). Serotypes were determined by agglutination of latex particles, which identified a subset of serotypes included in pneumococcal conjugate vaccines (1, 3, 4, 5, 14) and some of the serogroups. This was followed by the Neufeld test using monovalent antisera (Statens Serum Institute) specific for the other serotypes included in pneumococcal conjugate vaccines 7, 10 and 13 (PCV7, PCV10, PCV13): 6A, 6B, 7F, 9V, 18C, 19A, 19F and 23F. During the study period, 200 invasive and 310 non-invasive pneumococcal isolates were obtained from paediatric patients ranging in age from newborn to 16 years. Among these 510 isolates, 53.4% had reduced susceptibility to penicillin. Penicillin resistance was higher among S. pneumoniae isolates recovered from samples associated with non-invasive vs. invasive disease (60.6% vs. 45%). All the strains were susceptible to pristinamycin, vancomycin, teicoplanin and fosfomycin. Serotype 14 was the most frequently isolated serotype (22.2%), followed by serotypes 19F (15.5%) and 23F (10.3%). Of all strains typed, the percentage of serotypes covered by PCV7, PCV10 and PCV13 were 66.4%, 73% and 78%, respectively (76.1% for invasive pneumococcal isolates, 79.8% for non invasive pneumococcal isolates for PVC13). Continual surveillance of antibiotic susceptibility and careful use of antibiotics are recommended. The introduction of the new conjugate vaccine should be greatly beneficial for reducing pneumococcal invasive diseases among Tunisian children.

Charfi F ，Smaoui H ，Kechrid A 《-》

Epidemiologic characteristics, serotypes, and antimicrobial susceptibilities of invasive Streptococcus pneumoniae isolates in a nationwide surveillance study in Lebanon.

Invasive pneumococcal disease (IPD) associated with Streptococcus pneumonia is a major public health problem worldwide for all age groups, including in Lebanon. Prevention through vaccination remains the most valuable tool to decrease the burden of disease. Pneumococcal conjugate vaccine 7 (PCV7), marketed internationally including in the Middle East and North Africa region for the prevention of IPD, was introduced in Lebanon in 2006, followed by PCV10 and PCV13 in 2010. However, none of these is currently part of the Extended Program of Immunization schedule and published data on IPD incidence, pneumococcal serotypes and vaccine coverage in the region are lacking. The Lebanese Inter-Hospital Pneumococcal Surveillance Program is a surveillance system set up to determine the burden of IPD and the prevalent serotypes responsible. The aim of this prospective 6-year study carried out in 78 hospitals throughout Lebanon was to obtain such data to help health authorities make informed decisions on the implementation of pneumococcal vaccination at the national level. A total of 257 isolates of culture-confirmed Streptococcus pneumoniae were evaluated. Considering all age groups, vaccine coverage was 41.4%, 53.9%, and 67.2% for PCV7, PCV10, and PCV13 serotypes, respectively; for patients <2, 2-5, and >60 years of age, PCV7 coverage was 50%, 51%, and 35%, respectively; PCV10 coverage was 53%, 74%, 45%, respectively; and PCV13 coverage was 63%, 80%, and 68%, respectively. Overall, 17.4% of these isolates were penicillin-G non-susceptible using the latest established breakpoints and mortality occurred in 23.5% of the patients with non-susceptible isolates. In addition, 10.9% of isolates were multi-drug-resistant. The highest mortality rates were observed in the eldest (>60 years of age) and youngest (<2 years of age) patients. The most prevalent invasive serotypes identified were those found in currently available pneumococcal conjugate vaccines, emphasizing the importance of implementing the vaccine in the routine immunization schedule at the national level. Continuation of current surveillance practices will help assess the impact of vaccine implementation on IPD epidemiology, serotype distribution and antibiotic resistance patterns.

Hanna-Wakim R ，Chehab H ，Mahfouz I ，Nassar F ，Baroud M ，Shehab M ，Pimentel G ，Wasfy M ，House B ，Araj G ，Matar G ，Dbaibo G ，Lebanese Inter-Hospital Pneumococcal Surveillance Program ... -  《-》