Risk Factors For Pneumococcal Carriage Research Articles

Prevalence, capsular types, antimicrobial resistance and risk factors associated with pneumococcal carriage among children after long-term 10-valent pneumococcal conjugate vaccine use in Brazil.

The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced for childhood vaccination in Brazil's National Immunization Program in 2010. After nine years of PCV10 use, we investigated the carriage prevalence, capsular types, antimicrobial resistance and risk factors among children living in Niterói city, RJ, Brazil. Between September and December 2019, we conducted a cross-sectional study and recruited children under 6years of age. Antimicrobial susceptibility was evaluated by the disk-diffusion method and MICs to beta-lactams and macrolides were determined by E-test®. Capsular types were deduced by multiplex PCR. Logistic regression was used to predict risk factors for pneumococcal carriage. Seventy-five (17.4%) of the 430 children were pneumococcal carriers. The most frequent capsular types were 6C/D (14.7%), 11A/D (13.3%), and 23B (9.3%). PCV10 serotypes represented 5.3%. All isolates were susceptible to levofloxacin, linezolid, rifampicin, and vancomycin. Penicillin non-susceptible pneumococci (PNSP) made up 37.3%, with penicillin and ceftriaxone MICs ranging from 0.12 to 4.0μg/ml and 0.064-4.0μg/ml, respectively. Of the 19 (25.3%) erythromycin-resistant (ERY-R) isolates (macrolide MICs of 6 to>256μg/ml), most had the cMLSB phenotype (84.2%) and carried the erm(B) gene (73.7%). We detected 17 (22.6%) multidrug-resistant (MDR) isolates, strongly associated with serotype 6C/D. Presence of any symptoms, chronic diseases, childcare center attendance, living with young siblings, slum residence, and unstable income were predictors of pneumococcal carriage. Long-term universal childhood use of PCV10 has nearly eliminated carriage with PCV10 serotypes, but the high frequency of MDR isolates, especially associated with serotype 6C/D, remains a concern. Replacing PCV10 with PCV13 should reduce the proportion of ERY-R isolates and PNSP by at least 14% and 18%, respectively.

Risk factors for pneumococcal carriage in adults living with HIV on antiretroviral therapy in the infant pneumococcal vaccine era in Malawi.

Adults living with HIV (ALWHIV) on antiretroviral therapy (ART) are at high risk of pneumococcal carriage and disease. To help evaluate carriage risk in African ALWHIV at least 4 years after infant pneumococcal conjugate vaccination introduction in 2011, we assessed association between pneumococcal carriage and potential risk factors. Nasopharyngeal swabs were collected from adults aged 18-40 years attending an ART clinic during rolling, cross-sectional surveys in Blantyre, Malawi between 2015 and 2019. We fitted generalized additive models to estimate the risk of sex, social economic status (SES), living with a child less than 5 years, and ART duration on carriage. Of 2067 adults, median age was 33 years (range 28-37), 1427 (69.0%) were women, 1087 (61.4%) were in low-middle socioeconomic-status (SES), 910 (44.0%) were living with a child less than 5 years, and median ART duration was 3 years (range 0.004-17). We estimated 38.2 and 60.6% reductions in overall and vaccine-serotype carriage prevalence. Overall carriage was associated with low SES, living with a child less than 5 years and shorter duration on ART. By contrast, vaccine-type carriage was associated with living without a child less than 5 years and male sex. Despite temporal reductions in overall and vaccine-serotype carriage, there is evidence of incomplete vaccine-serotype indirect protection. A targeted-vaccination campaign should be considered for ALWHIV, along with other public health measures to further reduce vaccine-serotype carriage and therefore disease.

89Factors associated with pneumococcal nasopharyngeal carriage: a systematic review

Abstract Background Pneumococcal disease is a major contributor to global childhood morbidity and mortality. Pneumococcal carriage is a prerequisite for pneumococcal disease. Identifying factors associated with pneumococcal carriage can aid public health intervention programs. It is unknown if risk factors for pneumococcal carriage differ between low, middle, and high-income countries. We present preliminary findings of our systematic review of factors associated with pneumococcal carriage in community settings, in all ages. Methods A systematic search for pneumococcal nasopharyngeal carriage studies, published in English before July 2019. Two researchers independently reviewed studies that described factors associated with pneumococcal nasopharyngeal carriage. Study quality was assessed using the NIH Study Quality Assessment Tools. Results are presented as narrative summaries due to heterogeneity amongst factor definitions. Results Preliminary results are shown. Sixty-seven studies were included. 49% were conducted in high-income countries. Pneumococcal prevalence ranged from 0.3%-97%, 2.6%-89.6%, 14%-73%, 1.6%-82.4% in low-, lower-middle, upper-middle, and high-income classifications. Age, respiratory tract infection symptoms, living with young children, poverty, exposure to smoke, and season were positively associated with pneumococcal carriage in all income classifications. Conclusions Pneumococcal carriage prevalence was highest in low-income classifications. Pneumococcal carriage is associated with similar factors across income classifications. Differences in prevalence of risk factors associated with pneumococcal carriage by income classification may contribute to differences in carriage prevalence by income classifications. Key messages Pneumococcal carriage is considered a prerequisite for pneumococcal disease. Pneumococcal carriage prevalence is highest in low-income countries, however preliminary results suggest risk factors for carriage may be similar across income classifications.

Impact of thirteen-valent pneumococcal conjugate vaccine on nasopharyngeal carriage in healthy children under 24 months in Okinawa, Japan

In November 2013, a 13-valent pneumococcal conjugate vaccine (PCV13) for all infants aged younger than 5 years was incorporated into the Japan national immunization program. An annual survey of nasopharyngeal carriage rates was performed on healthy infants aged 2–24 months from Okinawa, Japan to evaluate the effect of PCV13 on pneumococcal colonization. Of 756 evaluable infants, 203 pneumococcal strains were detected in 193 infants. The overall nasopharyngeal carriage rate was 25.5%, which was not different from our previously reported isolation rate before the introduction of PCV13. The main serotypes of the Streptococcus pneumoniae strains are 15A (18.2%), non-typeable (14.8%), and 15B (11.8%). The carriage rates of pneumococcal strains with 7-valent pneumococcal conjugate vaccine serotypes and PCV13 serotypes were 3.0% and 9.9%, respectively. These values were significantly lower than we reported before the introduction of PCV13. However, the carriage rates of non-PCV13 serotypes have increased. Multivariate logistic regression analysis suggested that siblings and day care attendance are risk factors for pneumococcal carriage.

Factors associated with pneumococcal carriage and density in infants and young children in Laos PDR.

Nasopharyngeal carriage of Streptococcus pneumoniae (the pneumococcus) is a precursor to pneumococcal disease. Several host and environmental factors have been associated with pneumococcal carriage, however few studies have examined the relationship between host factors and pneumococcal carriage density. We sought to identify risk factors for pneumococcal carriage and density using data from cross-sectional pneumococcal carriage surveys conducted in the Lao People's Democratic Republic before and after the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13). Nasopharyngeal swabs were collected infants from aged 5-8 weeks old (n = 999) and children aged 12-23 months (n = 1,010), pneumococci detected by quantitative PCR, and a risk factor questionnaire completed. Logistic and linear regression models were used to evaluate associations between participant characteristics and pneumococcal carriage and density. In infants aged 5-8 weeks, living in a household with two or more children under the age of five years (aOR 1.97; 95% CI 1.39-2.79) and low family income (aOR 1.64; 95% CI 0.99-2.72) were positively associated with pneumococcal carriage. For children aged 12-23 months, upper respiratory tract infection (URTI) symptoms (aOR 2.64; 95% CI 1.97-3.53), two or more children under five in the household (aOR 2.40; 95% CI 1.80-3.20), and rural residence (aOR 1.84, 95% CI 1.35-2.50) were positively associated with pneumococcal carriage. PCV13 vaccination was negatively associated with carriage of PCV13 serotypes (aOR 0.60; 95% CI 0.44-0.83). URTI symptoms (p < 0.001), current breastfeeding (p = 0.005), rural residence (p = 0.012), and delivery by Caesarean section (p = 0.035) were associated with higher mean pneumococcal density in pneumococcal carriers (both age groups combined). This study provides new data on pneumococcal carriage and density in a high disease burden setting in southeast Asia.

Pneumococcal carriage among adults aged 50 years and older with co-morbidities attending medical practices in Rome, Italy

BackgroundData on Streptococcus pneumoniae carriage in adults with co-morbidities are limited. In this study we estimated the pneumococcal carriage among adults with co-morbidities and evaluated socio-demographic and clinical risk factors. The potential coverage of the current pneumococcal vaccines recommended for adults (PCV13 and PPV23) was also investigated. MethodsA cross-sectional study on S. pneumoniae carriage among unvaccinated adults ≥50 years with co-morbidities, presenting with or without acute respiratory symptoms at general practitioners in Rome, Italy, between October 2015 and July 2016 was conducted. Pneumococcal carriage was investigated by both cultural and molecular methods. Socio-demographic variables and co-morbidities were evaluated by logistic models as possible risk factors for pneumococcal carriage. ResultsOut of 248 patients (median age: 73 yrs; IQR: 65–79), 12 (4.8%) and 83 (33.5%) individuals were found colonized using cultural or molecular methods, respectively. Potential risk factors for pneumococcal colonization as ascertained by molecular methods were: low level of education (adjusted OR = 3.71, 95% CI: 1.62–9.40), winter months (December-March vs other months, adjusted OR = 2.56, 95% CI: 1.29–5.14), and presence of chronic lung diseases (adjusted OR = 2.18, 95% CI: 1.15–4.16). The combination of serotype-specific multiplex RT-PCR and conventional PCR allowed to identify 22 serotypes/group of serotypes, of which the most common were: 24F/24A/24B, 12F/12A/12B/44/46, 6A/6B, 14, 15B/15C, and 22F/22A. Prevalence of pneumococcal carriage due to PCV13 serotypes and non-PCV13 serotypes was 23.6% and 67.3%, respectively. Prevalence of colonization due to PPV23 serotypes was estimated to be 54.6%. ConclusionsA high prevalence of S. pneumoniae carriage was observed among adults with co-morbidities, especially among individuals affected by chronic lung diseases. These results support vaccine strategies based on the sequential administration of PCV13 and PPV23 to control potentially invasive pneumococcal strains in adults, especially in subjects with co-morbidities.

Pneumococcal Carriage and Vaccine Coverage in Retirement Community Residents

To evaluate pneumococcal immunization in older adults living in retirement communities and to measure nasopharyngeal carriage of Streptococcus pneumoniae to better assess the potential for herd protection from the 13-valent pneumococcal conjugate vaccine (PCV-13) in these settings. Cross-sectional observational study of adults aged 65 and older living in retirement communities to determine coverage with 23-valent pneumococcal vaccine (PPSV-23), coverage with PCV-13 in immuncompromised individuals according to 2012 Advisory Committee on Immunization Practices (ACIP) guidelines, and nasopharyngeal carriage of S. pneumoniae. Two retirement communities in North Carolina. Older adults recruited between December 2013 and April 2014 (N = 21, 64.8% female, mean age 81.4). A survey was used to assess chronic illnesses, immunization history, and potential risk factors for pneumococcal carriage; a chart review was used to confirm immunization history and abstract chronic conditions; and a nasopharyngeal swab was collected and cultured for S. pneumoniae. Eighty-seven percent of participants reported receiving PPSV-23 since age 65. Of the 16.2% of participants with an immunocompromising condition, only one had received PCV-13. Nasopharyngeal carriage with S. pneumoniae was detected in 1.9% (95% confidence interval = 0.0-3.8%) of participants. In this select sample, PPSV-23 coverage was high, but adherence to the ACIP recommendation for PCV-13 in immunocompromised groups was low. Nasopharyngeal carriage of S. pneumoniae was present, although infrequent, suggesting that immunization with PCV-13 could provide an individual benefit and a small degree of herd protection.

Risk factors for pneumococcal carriage in day care centers: a retrospective study during a 10-year period.

In this retrospective epidemiologic study, we present pneumococcal carriage data from 109 Swedish day care centers over a period of 10 years. Aspects of season, age, personnel and group size were studied. We found a significant seasonal variation in pneumococcal carriage. Group size was a significant risk factor for pneumococcal carriage. Pneumococcal carriage was 4.5 % in personnel.

Nasopharyngeal Carriage and Antimicrobial Susceptibility Pattern of Streptococcus Pneumoniae among Pediatric Outpatients at Gondar University Hospital, North West Ethiopia

Pneumonia caused by Streptococcus pneumoniae is the leading cause of death among children in Ethiopia. S. pneumoniae nasopharyngeal carriage can result in endogenous infections and bacterial spread in the community. S. pneumoniae drug resistance is rapidly increasing worldwide. The aim of the study was to assess the nasopharyngeal carriage and antimicrobial susceptibility pattern of S. pneumoniae among pediatric outpatients. A cross-sectional study was conducted on children aged ≤10 years from February to May of 2012. Data on potential risk factors were gathered using an interview-based questionnaire. Nasopharyngeal specimens were collected with a sterile plastic cotton tip swab. Bacteria were characterized by colony appearance, Gram staining, and optochin susceptibility and bile solubility tests. An antimicrobial susceptibility test was performed using the disk diffusion method. A logistic regression analysis was used to examine the possible risk factors. All tests with p value less than 0.05 were considered statistically significant. Of the 234 children screened, 41.03% carried S. pneumoniae. Age-related downward trend for S. pneumoniae carriages (50.9% in <3-year-olds, 40.7% in 3- to 5-year-olds, 40.0% in 5- to <8-year-olds, and 33.3% in 8- to 10-year-olds) were observed. Children living with siblings < 5 years old (p = 0.003) and in a house having one room (p = 0.004) were associated with higher S. pneumoniae carriage. S. pneumoniae showed 33.2% resistance to erythromycin and tetracycline, 29.2% to cotrimoxazole, 14.6% to chloramphenicol and ciprofloxacin, and 10.4% to penicillin. The S. pneumoniae carriage rate was higher among younger children. High antimicrobial resistance of S. pneumoniae against erythromycin, tetracycline, and cotrimoxazole was observed. Being in the young age group and living with younger children are risk factors for pneumococcal carriage.

The Impact of the Heptavalent Pneumococcal Conjugate Vaccine on Risk Factors for Streptococcus pneumoniae Carriage in Children

The aim of the study was to investigate whether the 7-valent pneumococcal conjugate vaccine (PCV7) alters common risk factors of nasopharyngeal carriage by Streptococcus pneumoniae in children. From July 2005 through December 2010, we performed a cross-sectional study investigating risk factors associated with pneumococcal carriage in children. Parents of participating children completed questionnaires including whether or not the children received PCV7 vaccination. Among 9705 children, 20.2% of them received at least 1 dose of the PCV7 vaccine. Multivariate logistic regression models identified older age, having 1 sibling in a family, history of acute otitis media and household exposure to smoking as independent risk factors for pneumococcal carriage in the unvaccinated group, but not associated with pneumococcal carriage in the vaccinated group. The number of siblings ≥2 in a family, history of upper respiratory tract infection and child-care attendance were strong factors associated with pneumococcal carriage in children, regardless of vaccination. In vaccinated group, breast-feeding was associated with increased nonvaccine type pneumococcal carriage, mainly in children with upper respiratory tract infection. PCV7 decreased the association between pneumococcal carriage and older age, 1 sibling in a family, history of acute otitis media and household exposure to smoking, but increased the association between pneumococcal carriage and breast-feeding.

Nasopharyngeal carriage of Streptococcus pneumoniae: prevalence and risk factors in HIV-positive children in Tanzania

Pneumococcal colonization of the nasopharynx is especially common in young children and is a pre-requisite for pneumococcal disease. Those with immunosuppression, such as HIV, are at higher risk of colonization and disease, especially at older ages. Currently, vaccination schedules are only offered to children under 6 months of age, despite the large impact of pneumococcal disease in older unvaccinated children with HIV. We conducted a study to assess the prevalence of, and risk factors for, pneumococcal carriage in HIV-positive children aged <15 years. We collected a single nasopharyngeal swab from 142 HIV-infected children aged 1-14 years over a 2-month period. To detect carriage of pneumococcus, these samples were cultured and serotyped; PCR was performed on negative samples. We also collected epidemiological data via survey and medical records. The overall carriage rate was 81% and was at least 76% in those aged 5-14 years. The 7-, 10-, and 13-valent pneumococcal vaccines would cover 37%, 37%, and 49% of children with carriage, respectively. In the multivariate analysis, we identified increase in weight since last visit (p=0.028) and the existence of care-givers who had respiratory symptoms in the past week (p=0.022) as risk factors for carriage. Weight gain was also significantly associated with antiretroviral use (p=0.002). These data illuminate the little known area of pneumococcal carriage in older HIV-infected children as well as finding novel risk factors for pneumococcal carriage, namely the association with household members who have respiratory symptoms and with an increase in the child's weight prior to swabbing. Weight gain may be due to an increase in health enabling more mobility and increasing the risk of acquiring carriage. The carriage rate observed (81%) is one of the highest recorded. Further research should address whether vaccination can prevent the acquisition of carriage and so protect against disease.

Étude du portage rhinopharyngé de Streptococcus pneumoniae et de sa sensibilité aux antibiotiques chez les enfants en bonne santé âgés de moins de 2 ans dans la région de Marrakech (Maroc)

The healthy carrier of Streptococcus pneumoniae (S. pneumoniae) has been studied very little at the national level. With the emergence of antibiotic-resistant strains worldwide, and the emergence of new serotypes, an epidemiological survey is needed before the vaccine can be introduced in Morocco. This study's objective was to determine the prevalence and risk factors of pneumococcal nasopharyngeal carriage in children less than 2 years of age in the Marrakech region and to assess the antibiotic susceptibility of the isolates and the serotypes present prior to the introduction of the conjugate pneumococcal vaccine. From 2008 to 2009, 660 nasopharyngeal samples were collected on children under 2 years of age during scheduled visits to dispensaries for routine immunization in the Marrakech region. S. pneumoniae carriage was found in 45.8% of children. Of the 660 samples, 302 strains were isolated. The percentage of pneumococcal strains with reduced susceptibility to penicillin (PRSP) was 34.7%. Among these strains, 87.1% showed low-level resistance and 12.9% high-level resistance. Resistance to amoxicillin was found in 3.3% of the strains and no strains were resistant to cefotaxime. Several risk factors for pneumococcal carriage were identified, the main ones being breastfeeding less than 2 months, the presence of more than one sibling, passive smoking, and low socioeconomic level. The most frequent serotypes were 19F, 6, 14, 23, 18, and 9. The study of the vaccine serotype distribution showed that the theoretical vaccine coverage of the 7 valent vaccines was at 57% for all the isolates. These data show the frequency and the risk factors on nasopharyngeal carriage, and report the status of penicillin resistance of strains carrying children less than 2 years of age in the Marrakech region. The fluctuation of circulating serotypes at the national level underscores the importance of epidemiological surveillance carried out before the introduction of the heptavalent vaccine in Morocco.

Impact of Conjugate Vaccine on Transmission of Antimicrobial-Resistant Streptococcus pneumoniae Among Alaskan Children

The impact of heptavalent pneumococcal conjugate vaccine (PCV7) on transmission of antimicrobial-resistant Streptococcus pneumoniae is an important concern for countries considering PCV7 introduction. Every winter from 2000 to 2004, as PCV7 was routinely introduced, we obtained nasopharyngeal swabs for pneumococcal culture, serotyping, and susceptibility testing from 150 children aged 3-59 months at each of 3 Anchorage, Alaska clinics. We assessed risk factors for pneumococcal carriage, including vaccination status and antimicrobial use. Between 2000 and 2004, 2250 nasopharyngeal swabs from 2061 infants and children were collected. The proportion of children receiving > or = 1 PCV7 vaccination increased from 0 to 89%, whereas overall pneumococcal carriage remained stable (38% versus 41%, respectively). Among S. pneumoniae carriers, we observed declines in carriage of PCV7 serotypes (from 54% to 10%, P < 0.01) and trimethoprim-sulfamethoxazole nonsusceptible strains (44% to 16%, P < 0.01), but not in PCN-nonsusceptible strains (36% versus 37%). Among PCN-nonsusceptible types, the proportion of serotype 19A strains increased from 10% to 32% (P = 0.0002). Recent beta-lactam use was stable throughout the period (29% overall), whereas trimethoprim-sulfamethoxazole use declined from 6% to 2% (P = 0.02). PCV7 vaccination in the first 5 years did not affect overall pneumococcal carriage, but was associated with a shift in serotype distribution from PCV7 types to non-PCV7 types. With persistent pressure of some antimicrobials, reductions in carriage of antimicrobial nonsusceptible PCV7 types may be offset by increases in carriage of nonsusceptible non-PCV7 types.

Impact of cotrimoxazole on non-susceptibility to antibiotics in Streptococcus pneumoniae carriage isolates among HIV-infected mineworkers in South Africa

To investigate risk factors for pneumococcal carriage and non-susceptibility among HIV-infected mineworkers in South Africa. In a cross-sectional study, HIV clinic attendees were questioned about risk factors for pneumococcal carriage and antimicrobial non-susceptibility. Oropharyngeal and nasopharyngeal swabs were taken for pneumococcal culture, serotyping and susceptibility testing. Among 856 participants (854 male, median age 41.5years, median CD4 290cells/mm(3)), 294 (34.3%) were receiving cotrimoxazole prophylaxis. Overall, 75/856 (8.8%) carried S. pneumoniae; among those taking vs. not taking cotrimoxazole, 8.2% vs. 9.1% were carriers. Risk factors for pneumococcal carriage were living with a child (adjusted OR 2.12, 95% CI 1.06-4.62) and recent hospitalisation (adjusted OR 1.80; 95% CI 0.98-3.30). Among participants not taking cotrimoxazole, the prevalence of carriage was higher in individuals with lower CD4 counts. Comparing participants taking cotrimoxazole vs. not, 60.9% vs. 22.4% (p=0.001) isolates were non-susceptible to cotrimoxazole and 30.4% vs. 8.2% were non-susceptible to penicillin (p=0.014). Thirty three/72 (45.8%) isolates were paediatric serotypes/groups. Nasopharyngeal compared with oropharyngeal swabs had higher sensitivity in detecting carriage (53/75, 70.7% vs. 31/75, 41.3%), and adding oropharyngeal sampling increased detection from 6.2% to 8.8%. Non-susceptibility to cotrimoxazole and penicillin was more common among isolates from participants taking cotrimoxazole prophylaxis. Surveillance for antimicrobial susceptibility is important where prophylaxis is used. Treatment for pneumococcal disease should take into account a higher risk of non-susceptibility to antibiotics amongst individuals taking cotrimoxazole prophylaxis.

The descriptive epidemiology of Streptococcus pneumoniae and Haemophilus influenzae nasopharyngeal carriage in children and adults in Kilifi district, Kenya.

Transmission and nasopharyngeal colonization are necessary steps en route to invasive pneumococcal or Haemophilus influenzae disease but their patterns vary geographically. In East Africa we do not know how these pathogens are transmitted between population subgroups nor which serotypes circulate commonly. We did 2 cross-sectional nasopharyngeal swab surveys selecting subjects randomly from a population register to estimate prevalence and risk-factors for carriage in 2004. H. influenzae type b vaccine was introduced in 2001. Of 450 individuals sampled in the dry season, 414 were resampled during the rainy season. Among subjects 0-4, 5-9, and 10-85 years old pneumococcal carriage prevalence was 57%, 41%, and 6.4%, respectively. H. influenzae prevalence was 26%, 24%, and 3.0%, respectively. Prevalence of H. influenzae type b in children <5 years was 1.7%. Significant risk factors for pneumococcal carriage were rainy season (odds ratio [OR]: 1.65), coryza (OR: 2.29), and coculture of noncapsulate H. influenzae (OR: 7.46). Coryza was also a risk factor for H. influenzae carriage (OR: 1.90). Of 128 H. influenzae isolates, 113 were noncapsulate. Among 279 isolates of Streptococcus pneumoniae, 40 serotypes were represented and the distribution of serotypes varied significantly with age; 7-valent vaccine-types, vaccine-related types, and nonvaccine types comprised 47%, 19%, and 34% of strains from children aged <5 years. Among older persons they comprised 25%, 28%, and 47%, respectively (P = 0.005). The study shows that pneumococcal carriage is common up to 9 years of age and that the majority of serotypes carried at all ages are not covered specifically by the 7-valent pneumococcal conjugate vaccine.

Prevalence, serotypes, and risk factors for pneumococcal carriage among HIV-infected adults

From March 2000 through April 2001, 385 HIV-positive individuals were evaluated to determine the prevalence of Streptococcus pneumoniae nasopharynx carriage, to determine antimicrobial susceptibility and serotypes, and to study factors associated with carriage. Each patient was interviewed, and a nasopharyngeal culture, HIV viral load, and CD4 lymphocyte count were obtained. Of 385 patients studied, 64 were carriers of S. pneumoniae (17%). Intermediate susceptibility to penicillin occurred in 18 isolates (28%) and there were no resistant isolates; 50% of the isolates belonged to 3 serotypes (14, 6B, and 9V). One isolate belonged to clone Spain 9V-3. Tobacco use and intravenous illicit drugs were associated with carriage; HIV viral load and CD4 lymphocyte level were not significantly associated with carriage. The use of the same unaltered antiretroviral regimen for a year or more was associated with a lower risk of colonization, suggesting that prolonged use of highly effective antiretroviral therapy lowers pneumococcal carriage and may lower the risk of infection.

Étude du portage rhinopharyngé de Streptococcus pneumoniae chez les enfants sains âgés de 2 à 24 mois en Nouvelle-Calédonie

The aims of this study were to determine the prevalence of pneumococcal nasopharyngeal carriage in New-Caledonian children less than two years of age, to define risk factors for carriage, and to document the serotypes present in New Caledonia prior to the implementation of the conjugate pneumococcal vaccine. From August 2002 to April 2003, nasopharyngeal samples were collected on 1040 children less than two years of age during scheduled visits to dispensaries for routine immunization. Of the 1040 samples, 544 (52%) were positive for Streptococcus pneumoniae. The percentage of pneumococcal strains with reduced susceptibility to penicillin (PRSP) was 21%. Several risk factors for pneumococcal carriage were identified. These included the Province that the child lived in, the ethnic group, age, and having a sibling less than 6 years of age. Risk factors for carriage of PRSP carriage were similar but also included additional risk factors such as attendance at day care and a history of antibiotic treatment. The eight most frequent serotypes were 6B, 19F, 14, 23F, 6A, 19A, 11A, and 16F. These serotypes accounted for 60% of all strains detected. The most frequent serotypes of PRSP were 14, 9 V, 19F, 23F, and 6B. They were more often identified in european children and 80% were vaccine serotypes. However, overall 250/544 (46%) of all pneumococcal isolates were those included in the 7 serotype vaccine.

Modeling Community- and Individual-Level Effects of Child-Care Center Attendance on Pneumococcal Carriage

The prevalence of pneumococcal carriage varies widely across communities. This variation is not fully explained by risk factors at the individual level but may be explained by factors producing effects at both the individual and community levels, such as child-care center (CCC) attendance. We developed a transmission model to evaluate whether the combined risks of attending CCCs and associating with playmates who attend CCCs account for a large proportion of the variability in the prevalence of pneumococcal carriage across communities. We based parameters for the model on data from a multicommunity study. According to our model, differences in the proportion of children who attend CCCs can account for a range of 4%-56% in the prevalence of pneumococcal carriage across communities. Our model, which was based on data collected from 16 Massachusetts communities, predicts that the odds of carriage associated with CCC attendance are 2-3 times the odds associated with no CCC attendance (individual-level effect). The model also predicts that the odds of carriage for nonattendees in a community with CCCs are up to 6 times the odds for children in a community without CCCs (community-level effect). In addition, the mean number of hours spent at CCCs by a single attendee appears to exert effects on pneumococcal carriage that are independent of either the proportion of CCC attendance in the community or the mean number of hours these attendees spend in child care. We used data from multiple communities to develop a transmission model that explains marked differences in pneumococcal carriage across communities by variations in CCC attendance. This model only accounts for CCC attendance among young children and does not include other known risk factors for pneumococcal carriage.