Phenotypic and genotypic characterization of Streptococcus pneumoniae resistant to macrolide in Casablanca, Morocco.
In Morocco, the 13-valent pneumococcal conjugate vaccine (PCV-13) was introduced in the national immunization program (NIP) in October 2010 and replaced by the PCV-10 in July 2012. The present study aimed to determine the prevalence of erythromycin-resistant Streptococcus pneumoniae (ERSP) and to analyze the phenotypic and genotypic characteristics of these isolates in Casablanca, Morocco from January 2007 to December 2014. Isolates were obtained from the Microbiology Laboratory of Ibn Rochd University Hospital Centre of Casablanca. Serogrouping was done using Pneumotest Kit and serotyping by the Quellung capsular swelling. Antibiotic susceptibility pattern was determined by disk diffusion and Etest methods. A total of 655S. pneumoniae isolates were collected from 2007 to 2014 from pediatric and adult patients. Fifty-five percent of these isolates were from invasive pneumococcal diseases. Of the 655 isolates, 92 (14%) were ERSP. Globally, the proportion of ERSP from 2007 to 2010 (before vaccination) and from 2011 to 2014 (after vaccination) were 11.6% and 17.2% (p=0.04), respectively. Of the 92 ERSP, 89%, 4% and 7% displayed constitutive MLSB (resistance to macrolide, lincosamide and streptogramin B), inducible MLSB, and M phenotype (resistance to macrolide only), respectively. ERSP genotypic analysis showed that 90.2% carried the ermB gene, 6.5% the mefE gene, and 3.3% both the genes (ermB+mefE). The most prevalent ERSP serotypes were 6B, 19F and 23F before vaccination and 19F, 6B, 6A and 23F after vaccination. Erythromycin resistance among S. pneumoniae is relatively high in Casablanca. The contribution of PCVs to the reduction in antibiotic use is encouraging but this should be accompanied by a rational use of antibiotic.
Diawara I
，Zerouali K
，Katfy K
，Barguigua A
，Belabbes H
，Timinouni M
，Elmdaghri N
... -
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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
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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
... -
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Serotype distribution and antimicrobial susceptibility of invasive Streptococcus pneumoniae isolates among adult and elderly population before and after introduction of pneumococcal conjugate vaccine in Casablanca, Morocco.
Streptococcus pneumoniae (S. pneumoniae), remains a major cause of mortality and morbidity worldwide. The objective of this study was to determine the trends of invasive pneumococcal diseases (IPD) in adult and elderly population in Casablanca (Morocco) before and after introduction of pneumococcal conjugate vaccine (PCV) by determining the distribution of pneumococcal serotypes and antibiotic resistance profile of isolated strains.
The proposed study is a retrospective laboratory-based surveillance of IPD in hospitalized adult (15-59 years old) and elderly (≥ 60 years old) patients in Ibn Rochd University Hospital Centre from 2007 to 2019 (13 years). All the 250 non-duplicate clinical invasive isolates from adult and elderly patients, confirmed as S. pneumoniae according to the laboratory standard identification procedures, are included in this study.
A significant decrease of the overall incidence in IPD was observed only in adults from 0.71 to 0.54/100000 populations (P = 0.02) and to 0.47/100000 populations (P = 0.0137) in the early and mature post-vaccine period respectively compared to the pre-vaccine period. Our results also showed a significant reduction in the overall prevalence of vaccine serotypes from 28.17 to 6.90% (P = 0.0021) for the PCV-10 serotypes, and from 46.48 to 25.86% (P = 0.0164) for the PCV-13 serotypes only in the mature post-vaccine period (2015-2019). In parallel, the rate of non-vaccine serotypes did not significantly change in the early post-vaccine period (2011-2014) while it increased considerably from 54 to 74.14% (P = 0.0189) during the mature post-vaccine period. The rate of penicillin non-susceptible pneumococcal isolates decreased significantly from 23.94 to 8.77% (P = 0.02) in adult patients, and the rate of cotrimoxazole non-susceptible pneumococcal isolates significantly decreased from 29.58 to 8.77% in the early post-vaccine period (P = 0.003) and to 7.24% in the mature post-vaccine period (P = 0.0007).
Although childhood vaccination has considerably reduced the incidence of IPD in adult population through the herd effect, IPD remain a real public health problem due to the alarming increase in non-vaccine serotypes (NVS) and the lack of herd effect among elderly population. The rate of antibiotic resistance was relatively low. Nevertheless, resistance constitutes a serious problem to the therapeutic arsenal due to the known capacity for genetic dissemination in the pneumococcus.
Nzoyikorera N
，Diawara I
，Katfy M
，Katfy K
，Maaloum F
，Nyandwi J
，Belabbes H
，Elmdaghri N
，Zerouali K
... -
《BMC INFECTIOUS DISEASES》
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