Serotype distribution and prevalence of resistance to benzylpenicillin in three representative populations of Streptococcus pneumoniae isolates from the coast of Kenya

Computational Investigation to Design Ofloxacin-Loaded Hybridized Nanocellulose/Lipid Nanogels for Accelerated Skin Repair

The pharmaceutical application of biomaterials has attained a great success. Rapid wound healing is an important goal for many researchers. Hence, this work deals with the development of nanocellulose crystals/lipid nanogels loaded with ofloxacin (OFX) to promote skin repair while inhibiting bacterial infection. Ofloxacin-loaded hybridized nanocellulose/lipid nanogels (OFX-HNCNs) were prepared and evaluated adopting a computational method based on regression analysis. The optimized nanogels (OFX-HNCN7) showed a spherical outline with an encapsulation efficiency (EE), particle size (PS) and zeta potential (ZP) values of 97.53 ± 1.56%, 200.2 ± 6.74 nm and -26.4 ± 0.50 mV, respectively, with an extended drug release profile. DSC examination of OFX-HNCN7 proved the amorphization of the encapsulated drug into the prepared OFX-HNCNs. Microbiological studies showed the prolonged inhibition of bacterial growth by OFX-HNCN7 compared to the free drug. The cytocompatibility of OFX-HNCN7 was proved by Sulforhodamine B assay. Tissue repair was evaluated using the epidermal scratch assay based on cell migration in human skin fibroblast cell line, and the results depicted that cell treated with OFX-HNCN7 showed a faster and more efficient healing compared to the control. In overall, the obtained findings emphasize the benefits of using the eco-friendly bioactive nanocellulose, hybridized with lipid, to prepare a nanocarrier for skin repair.

Analysing pneumococcal invasiveness using Bayesian models of pathogen progression rates

The disease burden attributable to opportunistic pathogens depends on their prevalence in asymptomatic colonisation and the rate at which they progress to cause symptomatic disease. Increases in infections caused by commensals can result from the emergence of “hyperinvasive” strains. Such pathogens can be identified through quantifying progression rates using matched samples of typed microbes from disease cases and healthy carriers. This study describes Bayesian models for analysing such datasets, implemented in an RStan package (https://github.com/nickjcroucher/progressionEstimation). The models converged on stable fits that accurately reproduced observations from meta-analyses of Streptococcus pneumoniae datasets. The estimates of invasiveness, the progression rate from carriage to invasive disease, in cases per carrier per year correlated strongly with the dimensionless values from meta-analysis of odds ratios when sample sizes were large. At smaller sample sizes, the Bayesian models produced more informative estimates. This identified historically rare but high-risk S. pneumoniae serotypes that could be problematic following vaccine-associated disruption of the bacterial population. The package allows for hypothesis testing through model comparisons with Bayes factors. Application to datasets in which strain and serotype information were available for S. pneumoniae found significant evidence for within-strain and within-serotype variation in invasiveness. The heterogeneous geographical distribution of these genotypes is therefore likely to contribute to differences in the impact of vaccination in between locations. Hence genomic surveillance of opportunistic pathogens is crucial for quantifying the effectiveness of public health interventions, and enabling ongoing meta-analyses that can identify new, highly invasive variants.

Increased pathogenicity of pneumococcal serotype 1 is driven by rapid autolysis and release of pneumolysin

Streptococcus pneumoniae serotype 1 is the predominant cause of invasive pneumococcal disease in sub-Saharan Africa, but the mechanism behind its increased invasiveness is not well understood. Here, we use mouse models of lung infection to identify virulence factors associated with severe bacteraemic pneumonia during serotype-1 (ST217) infection. We use BALB/c mice, which are highly resistant to pneumococcal pneumonia when infected with other serotypes. However, we observe 100% mortality and high levels of bacteraemia within 24 hours when BALB/c mice are intranasally infected with ST217. Serotype 1 produces large quantities of pneumolysin, which is rapidly released due to high levels of bacterial autolysis. This leads to substantial levels of cellular cytotoxicity and breakdown of tight junctions between cells, allowing a route for rapid bacterial dissemination from the respiratory tract into the blood. Thus, our results offer an explanation for the increased invasiveness of serotype 1.

The mechanisms behind the high invasiveness of Streptococcus pneumoniae serotype 1 are unclear. Here, Jacques et al. show that this feature is due to overproduction and rapid release of pneumolysin, which induces cytotoxicity and breakdown of tight junctions, allowing rapid bacterial dissemination from the respiratory tract into the blood.

Designing ecologically optimized pneumococcal vaccines using population genomics

Streptococcus pneumoniae (the pneumococcus) is a common nasopharyngeal commensal that can cause invasive pneumococcal disease (IPD). Each component of current protein-polysaccharide conjugate vaccines (PCVs) generally induces immunity specific to one of the approximately 100 pneumococcal serotypes, and typically eliminates it from carriage and IPD through herd immunity. Overall carriage rates remain stable owing to replacement by non-PCV serotypes. Consequently, the net change in IPD incidence is determined by the relative invasiveness of the pre- and post-PCV-carried pneumococcal populations. In the present study, we identified PCVs expected to minimize the post-vaccine IPD burden by applying Bayesian optimization to an ecological model of serotype replacement that integrated epidemiological and genomic data. We compared optimal formulations for reducing infant-only or population-wide IPD, and identified potential benefits to including non-conserved pneumococcal carrier proteins. Vaccines were also devised to minimize IPD resistant to antibiotic treatment, despite the ecological model assuming that resistance levels in the carried population would be preserved. We found that expanding infant-administered PCV valency is likely to result in diminishing returns, and that complementary pairs of infant- and adult-administered vaccines could be a superior strategy. PCV performance was highly dependent on the circulating pneumococcal population, further highlighting the advantages of a diversity of anti-pneumococcal vaccination strategies.

Streptococcus mitis Expressing Pneumococcal Serotype 1 Capsule

Streptococcus pneumoniae's polysaccharide capsule is an important virulence factor; vaccine-induced immunity to specific capsular polysaccharide effectively prevents disease. Serotype 1 S. pneumoniae is rarely found in healthy persons, but is highly invasive and a common cause of meningitis outbreaks and invasive disease outside of the United States. Here we show that genes for polysaccharide capsule similar to those expressed by pneumococci were commonly detected by polymerase chain reaction among upper respiratory tract samples from older US adults not carrying pneumococci. Serotype 1-specific genes were predominantly detected. In five oropharyngeal samples tested, serotype 1 gene belonging to S. mitis expressed capsules immunologically indistinct from pneumococcal capsules. Whole genome sequencing revealed three distinct S. mitis clones, each representing a cps1 operon highly similar to the pneumococcal cps1 reference operon. These findings raise important questions about the contribution of commensal streptococci to natural immunity against pneumococci, a leading cause of mortality worldwide.

Epidemiology of Serotype 1 Invasive Pneumococcal Disease, South Africa, 2003-2013

In South Africa, 7-valent pneumococcal conjugate vaccine (PCV) was introduced in April 2009 and replaced with 13-valent PCV in April 2011. We describe the epidemiology of serotype 1 Streptococcus pneumoniae disease during the pre- and post-PCV eras (2003-2013). Using laboratory-based invasive pneumococcal disease (IPD) surveillance, we calculated annual incidences, identified IPD clusters, and determined serotype 1-associated factors. Of 46,483 IPD cases, 4,544 (10%) were caused by serotype 1. Two clusters of serotype 1 infection were detected during 2003-2004 and 2008-2012, but incidence decreased after 2011. Among children <5 years of age, those who had non-serotype 1 IPD had shorter hospital stays, fewer cases of penicillin-nonsusceptible disease, and lower HIV prevalence and in-hospital death rates than did those with serotype 1 IPD; similar factors were noted for older patients. Serotype 1 IPD had distinctive clinical features in South Africa, and annual incidences fluctuated, with decreases noted after the introduction of PCV13.

Prevalence and correlates of treatment failure among Kenyan children hospitalised with severe community-acquired pneumonia: a prospective study of the clinical effectiveness of WHO pneumonia case management guidelines

Objective

To determine the extent and pattern of treatment failure (TF) among children hospitalised with community-acquired pneumonia at a large tertiary hospital in Kenya.

Methods

We followed up children aged 2–59 months with WHO-defined severe pneumonia (SP) and very severe pneumonia (VSP) for up to 5 days for TF using two definitions: (i) documentation of pre-defined clinical signs resulting in change of treatment (ii) primary clinician's decision to change treatment with or without documentation of the same pre-defined clinical signs.

Results

We enrolled 385 children. The risk of TF varied between 1.8% (95% CI 0.4–5.1) and 12.4% (95% CI 7.9–18.4) for SP and 21.4% (95% CI 15.9–27) and 39.3% (95% CI 32.5–46.4) for VSP depending on the definition applied. Higher rates were associated with early changes in therapy by clinician in the absence of an obvious clinical rationale. Non-adherence to treatment guidelines was observed for 70/169 (41.4%) and 67/201 (33.3%) of children with SP and VSP, respectively. Among children with SP, adherence to treatment guidelines was associated with the presence of wheeze on initial assessment (P = 0.02), while clinician non-adherence to guideline-recommended treatments for VSP tended to occur in children with altered consciousness (P < 0.001). Using propensity score matching to account for imbalance in the distribution of baseline clinical characteristics among children with VSP revealed no difference in TF between those treated with the guideline-recommended regimen vs. more costly broad-spectrum alternatives [risk difference 0.37 (95% CI −0.84 to 0.51)].

Conclusion

Before revising current pneumonia case management guidelines, standardised definitions of TF and appropriate studies of treatment effectiveness of alternative regimens are required.

Objectif

Déterminer l'ampleur et les caractéristiques de l’échec du traitement (ET) chez les enfants hospitalisés avec une pneumonie acquise dans la communauté dans un grand hôpital tertiaire du Kenya.

Méthodes

Nous avons suivi des enfants âgés de 2 à 59 mois avec une pneumonie sévère (PS) et une pneumonie très sévère (PTS) telles que définies par l’OMS, sur un maximum de cinq jours pour l’ET, en utilisant deux définitions: (a) documentation des signes cliniques prédéfinis ayant entraîné un changement du traitement, (b) décision primaire du clinicien de changer de traitement avec ou sans documentation des mêmes signes cliniques prédéfinis.

Résultats

Nous avons recruté 385 enfants. Le risque d’ET variait de 1,8% (IC95%: 0,4 à 5,1) à 12,4% (IC95%: 7,9 à 18,4) pour la PS et de 21,4% (IC95%: 15,9 à 27) à 39,3% (IC95%: 32,5 à 46,4) pour la PTS selon la définition appliquée. Des taux plus élevés étaient associés à des changements précoces du traitement par le clinicien en l'absence d'une justification clinique évidente. Le non-respect des directives de traitement a été observé pour 70/169 (41,4%) et 67/201 (33,3%) enfants avec une PS et une PTS respectivement. Chez les enfants avec une PS, le respect des directives de traitement était associé avec la présence d'une respiration sifflante au cours l’évaluation initiale (P = 0,02) tandis que le non respect par les cliniciens des traitements recommandés pour la PTS tendait à se produire chez les enfants avec une altération de la conscience (P <0,001). L'utilisation du score de propension correspondant pour tenir compte du déséquilibre dans la répartition des caractéristiques cliniques de base chez les enfants avec une PTS n'a révélé aucune différence dans l’ET entre ceux traités avec le régime recommandé par les directives et ceux traités par des alternatives plus coûteuses à large spectre (différence de risque: 0,37 (IC95%: -0,84 à 0,51).

Conclusion

Avant la révision des directives actuelles de prise en charge des cas de pneumonie, des définitions standard d’ET et des études appropriées de l'efficacité des traitements alternatifs sont nécessaires.

Objetivo

Determinar la extensión y el patrón del fallo en el tratamiento (FT) en niños hospitalizados con una neumonía adquirida en la comunidad, ingresados en un gran hospital terciario de Kenia.

Métodos

Hemos seguido a niños con edades entre los 2-59 meses con una neumonía severa (NS) y neumonía muy severa (NMS) según definición de la OMS de hasta cinco días para FT utilizando dos definiciones: (a) documentación de signos clínicos pre-definidos que resultaron en un cambio de tratamiento (b) decisión del clínico principal de cambiar el tratamiento con o sin documentación de los mismos signos clínicos pre-definidos.

Resultados

Incluimos a 385 niños. El riesgo de FT varió entre un 1.8% (IC 95% 0.4 a 5.1) y 12.4% (IC 95% 7.9 a 18.4) para NS y 21.4% (IC 95% 15.9 a 27) y 39.3% (IC 95% 32.5 a 46.4) para NMS dependiendo de la definición que se aplicase. Unas mayores tasas estaban asociadas con cambios tempranos en la terapia por el clínico y en ausencia de un razonamiento clínico obvio. Se observaba una no adherencia a las guías de tratamiento en 70/169 (41.4%) y 67/201 (33.3%) de los niños con NS y NMS respectivamente. Entre los niños con SP, la adherencia a las guías de tratamiento estaba asociada con la presencia de sibilancias en la evaluación inicial (P=0.02) mientras que la no adherencia del clínico a los tratamientos recomendados por las guías para NMS tendían a ocurrir en niños con un estado alterado de consciencia (P<0.001). Utilizando el pareamiento por puntaje de propensión para equilibrar los grupos en la distribución de las características clínicas de base de los niños con NMS, se observó que no existían diferencias en FT entre aquellos tratados con el régimen recomendado por las guías versus alternativas más costosas de amplio espectro (diferencias de riesgo 0.37 (IC 95% -0.84 a 0.51).

Conclusión

Antes de revisar las actuales guías de manejo de casos de neumonía, se requieren definiciones estandarizadas de FT y estudios apropiados de la efectividad del tratamiento de regímenes alternativos.

Pneumococcal carriage in sub-Saharan Africa--a systematic review

BACKGROUND

Pneumococcal epidemiology varies geographically and few data are available from the African continent. We assess pneumococcal carriage from studies conducted in sub-Saharan Africa (sSA) before and after the pneumococcal conjugate vaccine (PCV) era.

METHODS

A search for pneumococcal carriage studies published before 2012 was conducted to describe carriage in sSA. The review also describes pneumococcal serotypes and assesses the impact of vaccination on carriage in this region.

RESULTS

Fifty-seven studies were included in this review with the majority (40.3%) from South Africa. There was considerable variability in the prevalence of carriage between studies (I-squared statistic = 99%). Carriage was higher in children and decreased with increasing age, 63.2% (95% CI: 55.6-70.8) in children less than 5 years, 42.6% (95% CI: 29.9-55.4) in children 5-15 years and 28.0% (95% CI: 19.0-37.0) in adults older than 15 years. There was no difference in the prevalence of carriage between males and females in 9/11 studies. Serotypes 19F, 6B, 6A, 14 and 23F were the five most common isolates. A meta-analysis of four randomized trials of PCV vaccination in children aged 9-24 months showed that carriage of vaccine type (VT) serotypes decreased with PCV vaccination; however, overall carriage remained the same because of a concomitant increase in non-vaccine type (NVT) serotypes.

CONCLUSION

Pneumococcal carriage is generally high in the African continent, particularly in young children. The five most common serotypes in sSA are among the top seven serotypes that cause invasive pneumococcal disease in children globally. These serotypes are covered by the two PCVs recommended for routine childhood immunization by the WHO. The distribution of serotypes found in the nasopharynx is altered by PCV vaccination.

Invasive Pneumococcal Disease (IPD) Serotype Frequency in Iranian Patients

BACKGROUND

Streptococcuspneumoniae as a Gram positive diplococcic is a major worldwide causative agent of morbidity and mortality among young children and the aged. In addition, Streptococcus pneumoniae is a versatile human pathogen causing infectious disease ranging from mild infection (i.e. otitis media) to life therating pneumonia and meningitidis in many countries.

OBJECTIVES

The aim of this study was to determine the frequency type of Streptococcuspneumoniae in Invasive pneumococcal disease (IPD) in Iranian patients.

PATIENTS AND METHODS

A total of 135 Streptococcuspneumoniae strains were isolated from patients infectious suspected of invasive streptococcal disease. They were subjected to PCR and bacteriological methods. Out of which, 134 strains of S. pneumoniae were serotyped and confirmed by PCR method. The data were analyzed by SPSS version 17.0.

RESULTS

The results of this study showed some S. pneumoniae serotypes were found in both sexes and some only in one sex invasive infections. For example, serotypes 10, 14, 18 and 22 were only in female patients with infections.

CONCLUSIONS

The analysis of the results had suggested that serotypes 6 from Lung and 19 from Eye are the most abundant bacterial strains isolated from patients. The diseases could be prevented by using the Pneumococcal vaccine.

Estimating rates of carriage acquisition and clearance and competitive ability for pneumococcal serotypes in Kenya with a Markov transition model

BACKGROUND

There are more than 90 serotypes of Streptococcus pneumoniae, with varying biologic and epidemiologic properties. Animal studies suggest that carriage induces an acquired immune response that reduces duration of colonization in a nonserotype-specific fashion.

METHODS

We studied pneumococcal nasopharyngeal carriage longitudinally in Kenyan children 3-59 months of age, following up positive swabs at days 2, 4, 8, 16, and 32 and then monthly thereafter until 2 swabs were negative for the original serotype. As previously reported, 1868/2840 (66%) of children swabbed at baseline were positive. We estimated acquisition, clearance, and competition parameters for 27 serotypes using a Markov transition model.

RESULTS

Point estimates of type-specific acquisition rates ranged from 0.00025/d (type 1) to 0.0031/d (type 19F). Point estimates of time to clearance (inverse of type-specific immune clearance rate) ranged from 28 days (type 20) to 124 days (type 6A). For the serotype most resistant to competition (type 19F), acquisition of other serotypes was 52% less likely (95% confidence interval = 37%-63%) than in an uncolonized host. Fitness components (carriage duration, acquisition rate, lack of susceptibility to competition) were positively correlated with each other and with baseline prevalence, and were associated with biologic properties previously shown to associate with serotype. Duration of carriage declined with age for most serotypes.

CONCLUSIONS

Common S. pneumoniae serotypes appear superior in many dimensions of fitness. Differences in rate of immune clearance are attenuated as children age and become capable of more rapid clearance of the longest-lived serotypes. These findings provide information for comparison after introduction of pneumococcal conjugate vaccine.

Control of Streptococcus pneumoniae serotype 5 epidemic of severe pneumonia among young army recruits by mass antibiotic treatment and vaccination

During an outbreak of severe pneumonia among new army recruits, an epidemiological investigation combined with repeated nasopharyngeal/oropharyngeal cultures from sick and healthy contacts subjects was conducted. Fifteen pneumonia cases and 19 influenza-like illness cases occurred among 596 recruits over a 4-week period in December 2005. Pneumonia attack rates reached up to 5.5%. A single pneumococcus serotype 5 clone was isolated from blood or sputum cultures in 4 patients and 30/124 (24.1%) contacts. Immunization with 23-valent polysaccharide vaccine supplemented with a 2-dose azithromycin mass treatment rapidly terminated the outbreak. Carriage rates dropped to <1%, 24 and 45 days after intervention.

Serotype-related variation in susceptibility to complement deposition and opsonophagocytosis among clinical isolates of Streptococcus pneumoniae

The polysaccharide capsule is a major virulence factor of Streptococcus pneumoniae; it affects complement resistance and shields the bacterium from phagocytes. Certain capsular serotypes appear to be better able to cause invasive disease than others. Serotypes 1 and 5 are common causes of invasive disease but are rarely isolated from healthy carriers, whereas serotypes 6B and 23F are more frequently isolated from carriage than invasive disease. We have recently shown that serotypes 6B and 19F differ in resistance to complement C3 deposition and opsonophagocytic killing. In this study we assessed the complement resistance and susceptibility to opsonophagocytosis of several other serotypes targeted by the pneumococcal conjugate vaccines. Clinical isolates of serotypes 1, 4, 5, 14, 18C, and 23F were tested along reference strains of corresponding capsular types. The concentration of anticapsular antibodies required for opsonophagocytic killing correlated inversely with C3 deposition on the serotype. Serotype 1 was the most resistant of the clinical isolates to C3 deposition and, along with serotypes 5 and 19F, required the highest concentration of capsule antibodies for opsonophagocytic killing, whereas serotype 23F was the most sensitive to opsonophagocytosis. Sensitivity to C3 deposition and opsonophagocytosis was associated with serotype-specific mortality of invasive pneumococcal disease, suggesting that the primary pathogens, such as serotypes 1 and 5, are more resistant to complement and require a higher concentration of capsule antibodies for opsonophagocytic killing than the opportunistic serotypes such as 6B and 23F, which are associated with a more severe disease outcome.

Estimating the proportion of pneumonia attributable to pneumococcus in Kenyan adults: latent class analysis

BACKGROUND

Community-acquired pneumonia is a common cause of hospitalization among African adults, and Streptococcus pneumoniae is assumed to be a frequent cause. Pneumococcal conjugate vaccine is currently being introduced into childhood immunization programs in Africa. The case for adult vaccination is dependent on the contribution of the pneumococcus to the hospital pneumonia burden.

METHODS

Pneumococcal diagnosis is complex because there is no gold standard, and culture methods are invalidated by antibiotic use. We used latent class analysis to estimate the proportion of pneumonia episodes caused by pneumococcus. Furthermore, we extended this methodology to evaluate the effect of antimicrobial treatment on test accuracies and the prevalence of the disease. The study combined data from 5 validation studies of pneumococcal diagnostic tests performed on 281 Kenyan adults with pneumonia.

RESULTS

The proportion of pneumonia episodes attributable to pneumococcus was 0.46 (95% confidence interval = 0.36-0.57). Failure to account for the effect of antimicrobial exposure underestimates this proportion as 0.32. A history of antibiotic exposure was a poor predictor of antimicrobial activity in patients' urine. Blood culture sensitivity for pneumococcus was estimated at 0.24 among patients with antibiotic exposure, and 0.75 among those without.

CONCLUSIONS

The large contribution of pneumococcus to adult pneumonia provides a strong case for the investigation of pneumococcal vaccines in African adults.

Impact of cotrimoxazole on carriage and antibiotic resistance of Streptococcus pneumoniae and Haemophilus influenzae in HIV-infected children in Zambia

This is a substudy of a larger randomized controlled trial on HIV-infected Zambian children, which revealed that cotrimoxazole prophylaxis reduced morbidity and mortality despite a background of high cotrimoxazole resistance. The impact of cotrimoxazole on the carriage and antibiotic resistance of Streptococcus pneumoniae and Haemophilus influenzae as major causes of childhood mortality in HIV-infected children was investigated since these are unclear. Representative nasopharyngeal swabs were taken prior to randomization for 181 of 534 children (92 on cotrimoxazole and 89 on placebo). Bacterial identification and antibiotic susceptibility were performed by routine methods. Due to reduced mortality, prophylactic cotrimoxazole increased the median time from randomization to the last specimen from 48 to 56 months (P = 0.001). The carriage of H. influenzae was unaltered by cotrimoxazole. Carriage of S. pneumoniae increased slightly in both arms but was not statistically significant in the placebo arm. In S. pneumoniae switching between carriage and no carriage in consecutive pairs of samples was unaffected by cotrimoxazole (P = 0.18) with a suggestion that the probability of remaining carriage free was lower (P = 0.10). In H. influenzae cotrimoxazole decreased switching from carriage to no carriage (P = 0.02). Cotrimoxazole resistance levels were higher in postbaseline samples in the cotrimoxazole arm than in the placebo arm (S. pneumoniae, P < 0.0001; H. influenzae, P = 0.005). Cotrimoxazole decreased switching from cotrimoxazole resistance to cotrimoxazole sensitivity in S. pneumoniae (P = 0.002) and reduced the chance of H. influenzae remaining cotrimoxazole sensitive (P = 0.05). No associations were observed between the percentage of CD4 (CD4%), the change in CD4% from baseline, child age at date of specimen, child gender, or sampling month with carriage of either pathogen.

High rate of pneumococcal bacteremia in a prospective cohort of older children and adults in an area of high HIV prevalence in rural western Kenya

BACKGROUND

Although causing substantial morbidity, the burden of pneumococcal disease among older children and adults in Africa, particularly in rural settings, is not well-characterized. We evaluated pneumococcal bacteremia among 21,000 persons > or =5 years old in a prospective cohort as part of population-based infectious disease surveillance in rural western Kenya from October 2006-September 2008.

METHODS

Blood cultures were done on patients meeting pre-defined criteria--severe acute respiratory illness (SARI), fever, and admission for any reason at a referral health facility within 5 kilometers of all 33 villages where surveillance took place. Serotyping of Streptococcus pneumoniae was done by latex agglutination and quellung reaction and antibiotic susceptibility testing was done using broth microdilution. We extrapolated incidence rates based on persons with compatible illnesses in the surveillance population who were not cultured. We estimated rates among HIV-infected persons based on community HIV prevalence. We projected the national burden of pneumococcal bacteremia cases based on these rates.

RESULTS

Among 1,301 blood cultures among persons > or =5 years, 52 (4%) yielded pneumococcus, which was the most common bacteria isolated. The yield was higher among those > or =18 years than 5-17 years (6.9% versus 1.6%, p < 0.001). The highest yield was for inpatients with SARI (10%), compared with SARI outpatients (3%) and acute febrile outpatients (1%). Serotype 1 pneumococcus was most common (42% isolates) and 71% were serotypes included in the 10-valent pneumococcal conjugate vaccine (PCV10). Non-susceptibility to beta-lactam antibiotics was low (<5%), but to trimethoprim-sulfamethoxazole was high (>95%). The crude rate of pneumococcal bacteremia was 129/100,000 person-years, and the adjusted rate was 419/100,000 person-years. Nineteen (61%) of 31 patients with HIV results were HIV-positive. The adjusted rate among HIV-infected persons was 2,399/100,000 person-years (Rate ratio versus HIV-negative adults, 19.7, 95% CI 12.4-31.1). We project 58,483 cases of pneumococcal bacteremia will occur in Kenyan adults in 2010.

CONCLUSIONS

Pneumococcal bacteremia rates were high among persons > or =5 years old, particularly among HIV-infected persons. Ongoing surveillance will document if expanded use of highly-active antiretroviral treatment for HIV and introduction of PCV10 for Kenyan children (anticipated in late 2010) result in substantial secondary benefits by reducing pneumococcal disease in adults.

Effect of presumptive co-trimoxazole prophylaxis on pneumococcal colonization rates, seroepidemiology and antibiotic resistance in Zambian infants: a longitudinal cohort study

OBJECTIVE

To ascertain the microbiological consequences of WHO's recommendation for presumptive co-trimoxazole prophylaxis for infants with perinatal HIV exposure.

METHODS

Using a longitudinal cohort design, we followed HIV-exposed and HIV-unexposed infants trimonthly for up to 18 months per infant. HIV-exposed infants received daily co-trimoxazole prophylaxis from 6 weeks to > or = 12 months of age. Using Streptococcus pneumoniae as our sentinel pathogen, we measured how co-trimoxazole altered nasopharyngeal colonization, pneumococcal resistance to antibiotics and serotype distribution as a function of co-trimoxazole exposure.

FINDINGS

From 260 infants followed for 3096 patient-months, we detected pneumococci in 360/1394 (25.8%) samples. HIV-exposed infants were colonized more frequently than HIV-unexposed infants (risk ratio, RR: 1.4; 95% confidence interval, CI: 1.0-1.9, P = 0.04). Co-trimoxazole prophylaxis reduced colonization by ca 7% but increased the risk of colonization with co-trimoxazole-resistant pneumococci within 6 weeks of starting prophylaxis (RR: 3.2; 95% CI: 1.3-7.8, P = 0.04). Prophylaxis with co-trimoxazole led to a small but statistically significant increase of nasopharyngeal colonization with pneumococci not susceptible to clindamycin (RR: 1.6; 95% CI: 1.0-2.6, P = 0.04) but did not increase the risk of non-susceptibility to penicillin (RR: 1.1; 95% CI: 0.7-1.7), erythromycin (RR: 1.0; 95% CI: 0.6-1.7), tetracycline (RR: 0.9; 95% CI: 0.6-1.5) or chloramphenicol (RR: 0.8; 95% CI: 0.3-2.3). Co-trimoxazole prophylaxis did not cause the prevailing pneumococcal serotypes to differ from those that are targeted by the 7-valent conjugate pneumococcal vaccine (RR: 1.0; 95% CI: 0.7-1.6).

CONCLUSION

Co-trimoxazole prophylaxis modestly suppresses pneumococcal colonization but accelerates infant acquisition of co-trimoxazole- and clindamycin-resistant pneumococci. Co-trimoxazole prophylaxis appears unlikely to compromise the future efficacy of conjugate vaccines.

Age- and serotype-specific pediatric invasive pneumococcal disease: insights from systematic surveillance in Santiago, Chile, 1994--2007

BACKGROUND

We monitored pediatric invasive pneumococcal disease (IPD) in Santiago, Chile, from 1994 to 2007.

METHODS

Three related data sets were generated: (1) IPD cases requiring hospitalization, 1994--2007; (2) cases of bacteremia detected among febrile patients aged 0-35 months seen in emergency departments, 2000--2007; and (3) nasopharyngeal carriage of pneumococcal serotypes, determined from repetitive culturing, among 524 newborns followed up through age 23 months.

RESULTS

Of 2369 IPD cases requiring hospitalization, 1878 (79.3%) occurred in those aged 0-59 months, and 1200 (50.7%) occurred in those aged 6-35 months. Among infants aged 0-5 months, meningitis and sepsis comprised 48.4% of all IPD cases (serotype 5 predominated); among those 6-35 months old, 522 (43.5%) of 1200 cases were bacteremic pneumonia (serotype 14 predominated). Serotype 1 peritonitis was common among 5-14-year-old girls. Meningitis and sepsis exhibited high case fatality rates (14%-29%) among all ages. Remarkably, 34 (28.8%) of 118 children with sepsis died, versus 1 fatality (0.4%) among 276 children hospitalized with bacteremia without a focus (P < .001, Fisher's exact test). Serotype 5 was significantly more common among hospitalized patients < 36 months of age, whereas serotype 18C was overrepresented among ambulatory patients. The annual incidence of serotype 14 was stable; those of serotypes 1 and 5 fluctuated markedly. Serotypes 14, 5, and 1 were overrepresented among invasive compared with nasopharyngeal isolates.

CONCLUSIONS

Clinical syndromes of IPD and predominant serotypes vary with age.

The roles of pneumococcal serotypes 1 and 5 in paediatric invasive disease

A small number of serotypes are responsible for most invasive pneumococcal disease in children worldwide. Serotypes 1 and 5 were among the first pneumococcal serotypes to be identified, reflecting their great prominence as causes of disease in the early part of the 20th century. In the antibiotic era, these serotypes persist as important causes of disease in children in most countries even though they, unlike some other common serotypes, remain sensitive to antimicrobial agents. These types also exhibit a high level of virulence, cause disease clusters or outbreaks, infect all age groups, and cause severe disease. Future vaccine formulations that protect against these types are important for developed and developing countries alike.

Human immunodeficiency virus infection and pediatric bacterial meningitis in developing countries

Over a million children are infected by the human immunodeficiency virus (HIV); most of whom live in the developing world. Bacterial meningitis is a serious infection of childhood that is 10 times more common in resource-constrained settings than well-resourced countries, and the outcome is worse. This paper reviews the relationship of bacterial meningitis to HIV infection and also the effect of HIV status on antibiotic sensitivity to common causes of childhood meningitis. The combined effects on outcome and long-term sequelae of meningitis are discussed and illustrated with results from Malawi and Southern Africa.

Serotype distribution and antibiotic susceptibility of invasive and nasopharyngeal isolates of Streptococcus pneumoniae among children in rural Mozambique

OBJECTIVE

To describe and compare serotype distribution and antibiotic susceptibility of invasive and nasopharyngeal isolates of Streptococcus pneumoniae from children in rural Mozambique.

METHODS

From August 2002 to July 2003, we prospectively obtained invasive pneumococcal isolates from children <15 years of age admitted to the paediatric ward of Manhiça District Hospital. During a cross-sectional study of children <5 years of age with mild illnesses, attending the outpatient department of the hospital in March and April 2003, we collected nasopharyngeal isolates. Serotypes and antibiotic susceptibilities were determined using standardized methods.

RESULTS

The two most common pneumococcal serotypes among invasive isolates were types 1 (40% of 88 isolates serotyped) and 5 (10%), but these types were rare among nasopharyngeal isolates. Compared with invasive isolates, nasopharyngeal isolates were more likely to be serotypes in the licensed seven-valent conjugate vaccine (49%vs. 20%, P < 0.01), to have intermediate-level penicillin resistance (52%vs. 14%, P < 0.01) and to be non-susceptible to trimethoprim-sulfamethoxazole (61%vs. 45%, P < 0.01). Recent receipt of antibiotics or sulfadoxine/pyrimethamine were associated with carriage of antibiotic non-susceptible isolates.

CONCLUSIONS

These data indicate that a pneumococcal conjugate vaccine containing serotypes 1 and 5 could substantially reduce pneumococcal invasive disease among young children in rural Mozambique. Carriage surveys can overestimate potential coverage of the seven-valent pneumococcal conjugate vaccine in settings where serotypes 1 and 5 predominate.

Serotypes of carriage and invasive isolates of Streptococcus pneumoniae in Brazilian children in the era of pneumococcal vaccines

Nasopharyngeal carriage of Streptococcus pneumoniae is a key factor in the development of invasive disease and the spread of resistant strains within the community. A single nasopharyngeal swab was obtained from 648 unvaccinated children aged <5 years, either healthy or with acute respiratory tract infection or meningitis, during the winters of 2000 and 2001. The overall pneumococcal carriage rate was 35.8% (95% CI 32.1-39.6). The pneumococcal serotypes found most frequently in the nasopharynx were 14, 6B, 6A, 19F, 10A, 23F and 18C, which included five of the seven serotypes in the currently licensed seven-valent conjugate vaccine (PCV7); serotypes 4 and 9V were less common. Serotypes 1 and 5 were isolated rarely from the nasopharynx. A comparison of 222 nasopharyngeal isolates with 125 invasive isolates, matched for age and time to the carrier isolates, showed a similar prevalence of penicillin non-susceptible pneumococci (PNSp) (19.8% and 19.2%, respectively). PNSp serotypes were similar (6B, 14, 19F, 19 A, 23B and 23F) for carriage and invasive disease isolates. The coverage of PCV7 for carriage isolates (52.2%) and invasive isolates (62.4%) did not differ significantly (p 0.06); similarly, there was no significant difference in PCV7 coverage for carriage isolates (34.5%) and invasive isolates (28.2%) of PNSp. These data suggest that PCV7 has the potential to reduce pneumococcal carriage and the number of carriers of PNSp belonging to vaccine serotypes.

Fatal meningitis in a previously healthy young adult caused by Streptococcus pneumoniae serotype 38: an emerging serotype?

BACKGROUND

In December 2001, a fatal case of pneumococcal meningitis in a Marine Corps recruit was identified. As pneumococcal vaccine usage in recruit populations is being considered, an investigation was initiated into the causative serotype.

CASE PRESENTATION

Traditional and molecular methods were utilized to determine the serotype of the infecting pneumococcus. The pneumococcal isolate was identified as serotype 38 (PS38), a serotype not covered by current vaccine formulations. The global significance of this serotype was explored in the medical literature, and found to be a rare but recognized cause of carriage and invasive disease.

CONCLUSION

The potential of PS38 to cause severe disease is documented in this report. Current literature does not support the hypothesis that this serotype is increasing in incidence. However, as we monitor the changing epidemiology of pneumococcal illness in the US in this conjugate era, PS38 might find a more prominent and concerning niche as a replacement serotype.

Bacterial infections in children with HIV/AIDS

HIV/AIDS affects over 850,000 children in Africa. Bacterial infections are frequent in this group of children. Pneumonia, meningitis and septicaemia are especially common, recurrent and most often caused by Streptococcus pneumoniae. Salmonella spp are the most frequently isolated causative agent of septicaemia in malarial areas. Soft tissue, eye and oral infections have a higher incidence in HIV-infected than uninfected children. In all instances the causative agents are not dissimilar from those that cause disease in HIV-uninfected children, but the mortality is greater. Increased bacterial resistance to first line antibiotics has been reported and the use of cotrimoxazole prophylaxis may further influence the resistance pattern of common bacteria.

What can children gain from pneumococcal conjugate vaccines?

In excess of 1 million young children die every year as a consequence of disease caused by Streptococcus pneumoniae, the vast majority in developing countries. Although the first vaccine against the Pneumococcus was produced before the First World War, licensure of the first vaccine with documented efficacy against severe infections in infants and young children did not occur until February 2000 in the United States. This conjugate vaccine consists of purified polysaccharide, from each of seven pneumococcal serotypes, chemically linked to a carrier protein. A high degree of efficacy of the new vaccine against potentially life-threatening infections has been shown in both poor and affluent countries. The vaccine's potential to protect from acute otitis media, however, is very limited, although encouraging indirect effects, such as reduced antibiotic prescriptions, have been reported. An inherent problem with the new pneumococcal conjugate vaccines is that, while more than 20 pneumococcal serotypes may cause invasive disease, only a more limited number of polysaccharides, 11 or so, can in practice be conjugated to carrier protein as part of a single vaccine formulation. Because of variation in the ranking of serotypes most commonly responsible for pneumococcal disease, by region, age and disease manifestation, compromise was required in selecting serotype-specific saccharides for inclusion.

CONCLUSION

Complex conjugate technology comes at a price, and the present costs keep most of the world's children far out of reach of an effective vaccine. However, the pneumococcal conjugate vaccine is a highly functional weapon against deadly pneumococcal infections, and strenuous efforts are needed to maximise its accessibility to children most at risk.

Invasive pneumococcal infections among hospitalized children in Bamako, Mali

BACKGROUND

Prevention of invasive pneumococcal disease (IPD) in children is a global public health priority, and determination of the most common serotypes is crucial for vaccine development and implementation.

METHODS

We performed prospective surveillance for IPD in hospitalized children in Bamako, Mali. All febrile children and others suspected to have invasive bacterial disease had an admission blood culture and cultures of additional anatomic sites when indicated. Standard microbiologic methods were used to identify, serotype and determine antibiograms for pneumococcal isolates.

RESULTS

Of 2,049 children enrolled, 106 (5%) had an IPD, including 47 cases of meningitis and 44 bacteremic pneumonias. The incidence was highest in infants (84/100,000/year). The overall IPD case fatality rate was 24%. Only 2 of 96 isolates were nonsusceptible to penicillin. The serotypes isolated were 5 (54%), 2 (14%), 7F (10%), 19F (8%), 6A/B (3%), 9V (3%), 1 (2%) and 14 (1%).

CONCLUSIONS

IPD is common and frequently fatal among hospitalized children in Mali, but surprisingly little resistance has occurred. Notably, 91% of the serotypes causing IPD in Bamako children are found in the 11-valent pneumococcal conjugate vaccine.

Tolerability and immunogenicity of an eleven valent mixed carrier Streptococcus pneumoniae capsular polysaccharide-diphtheria toxoid or tetanus protein conjugate vaccine in Finnish and Israeli infants

BACKGROUND

To have wide global coverage of pneumococcal serotypes, the number of serotypes covered by the current 7-valent pneumococcal conjugate vaccine must be increased. We have studied the safety and immunogenicity of an 11-valent mixed carrier vaccine (PncDT11) in infants.

METHODS

The study vaccine contained polysaccharide antigens of serotypes 1, 4, 5, 7F, 9V, 19F and 23F conjugated to tetanus protein and serotypes 3, 6B, 14 and 18C conjugated to diphtheria toxoid. The vaccine was administered to Finnish (n = 117) and Israeli (n = 135) infants at ages 2, 4, 6 and 12 months concomitantly with other vaccines used in national vaccination programs. IgG antibodies to polysaccharides were determined by enzyme immunoassay from serum samples taken at ages 2, 7, 12 and 13 months. After each injection the infants were followed for 30 min to detect any immediate adverse reactions, and parents were given a diary card to report any adverse events during the next 5 days.

RESULTS

No severe adverse reactions occurred, and immediate adverse reactions were rare. After each dose approximately 30% of the vaccinees experienced local reactions of which pain was the most common. Fever of >38 degrees C was reported in 33 to 53% of the vaccinees and high fever (>40 degrees C) was reported 6 times. The PncDT11 vaccine was immunogenic. The antibody concentrations after primary immunization series were higher in Israeli than in Finnish infants, but the differences were not significant for most serotypes. The difference was most marked at 13 months, a time point at which the difference was significant in 10 of 11 serotypes.

CONCLUSION

PncDT11 is safe and immunogenic in infants. The use of 11-valent pneumococcal vaccine would increase the serotype coverage beyond the currently available 7-valent vaccine.

Geographic distribution and clonal diversity of Streptococcus pneumoniae serotype 1 isolates

Serotype 1 pneumococci are a major cause of serious disease and have been associated with outbreaks but are rarely carried. The high attack rate and lack of coverage of this serotype by the heptavalent conjugate vaccine prompted the characterization of a geographically diverse collection of 166 serotype 1 isolates from recent cases of invasive disease. The isolates were resolved by multilocus sequence typing into 16 clones, which clustered into three major lineages with very different geographic distributions. Lineage A isolates were exclusively from Europe and North America, lineage B isolates were predominantly from Africa and Israel, and lineage C isolates were mainly from Chile. There was no clear association between the presence of individual clones within a country and the prevalence of serotype 1 disease.

Poor potential coverage for 7-valent pneumococcal conjugate vaccine, Malawi

Streptococcus pneumoniae infections can be prevented by using new conjugate vaccines, but these vaccines have limited serogroup coverage. We report the first serogrouping data from carried and invasive isolates obtained from children and adults in Malawi. The 7-valent vaccine would cover 41% of invasive isolates from children and 25% from adults. A 9-valent vaccine, including types 1 and 5, would cover 66% of invasive isolates from children and 55% from adults.

Geographic diversity and temporal trends of antimicrobial resistance in Streptococcus pneumoniae in the United States

Resistance of Streptococcus pneumoniae to antibiotics is increasing throughout the United States, with substantial variation among geographic regions. We show that patterns of geographic variation are best explained by the intensity of selection for resistance, which is reflected by differences between the proportions of resistance within individual serotypes, rather than by differences between the frequencies of particular serotypes. Using a mathematical transmission model, we analyzed temporal trends in the proportions of singly and dually resistant organisms and found that pneumococcal strains resistant to both penicillin and erythromycin are increasing faster than strains singly resistant to either. Using the model, we predict that by 1 July 2004, in the absence of a vaccine, 41% of pneumococci at the Centers for Disease Control and Prevention (CDC)'s Active Bacterial Core surveillance (ABCs) sites, taken together, will be dually resistant, with 5% resistant to penicillin only and 5% to erythromycin only.

Efficacy of polysaccharide pneumococcal vaccine in adults in more developed countries: the state of the evidence

We review studies on the efficacy against disease caused by Streptococcus pneumoniae of the 23-valent polysaccharide pneumococcal vaccine in adult populations in the more developed countries. Meta-analyses of primary vaccine trials have attempted to reduce uncertainty from lack of power. Vaccine efficacy calculated from studies in South African gold-miners and in Papua New Guinea, with high attack rates and differing serotype patterns, cannot automatically be applied to more developed countries. Meta-analyses will overestimate a protective effect if this clinical heterogeneity is ignored. Meta-analyses limited to trials in the more developed setting show no protective effect against pneumococcal pneumonia and a non-significant protective effect against bacteraemia. Lack of a specific diagnosis limits the ability to detect a protective effect against pneumococcal pneumonia. Most, but not all, observational studies confirm a protective effect against bacteraemia. An effect on mortality in more developed countries has yet to be documented.

Antibiotic resistance in Streptococcus pneumoniae in six Latin American countries: 1993-1999 surveillance

The impact of invasive pneumococcal invasive disease is increased by the emergence of antibiotic resistance. We report regional and temporal variations in antibiotic resistance for 4,105 invasive Streptococcus pneumoniae isolates collected from Latin American children <5 years, between 1993 and 1999. Reduced susceptibility to penicillin was detected in 1,182 isolates (28.8%); 36% of these were resistant (> or = 2 microg/ml), including 12.6% with MIC > or = 4 microg/ml, occurring primarily in serotypes 14 and 23F. Reduced susceptibility to third-generation cephalosporins was detected in 12.1% of the collection. Mexico had the highest proportion of reduced susceptibility to penicillin (51.6%) and to third-generation cephalosporins (22%), whereas Brazil had the lowest at 20.9% and 0.7%, respectively. Isolates cultured from patients with pneumonia were more likely to have reduced susceptibility to third-generation cephalosporins than isolates from patients with meningitis (p < 0.0001). Susceptibility to trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, and vancomycin was tested by disk diffusion for 2.899 isolates. Reduced susceptibility was observed for 45.6%, 11.5%, 6.9%, and 0%, respectively. Thirty-one percent of the strains were resistant to > or = 2 drugs. High levels of antibiotic resistance in Latin America emphasize the need for the development of and adherence to rational antibiotic use guidelines. On-going surveillance will monitor the impact of these programs.

Epidemiology of penicillin resistance in Streptococcus pneumoniae isolates in Kayseri, Turkey

OBJECTIVE

To determine the penicillin resistance and serotype distribution of Streptococcus pneumoniae strains and to identify clonal relationships of isolates resistant to penicillin by means of pulsed-field gel electrophoresis (PFGE).

METHODS

In total, 193 S. pneumoniae strains were isolated from clinical specimens between November 1997 and January 2000. Susceptibility testing was carried out by E test, and serotyping by the Quellung reaction. Clonal relationship was analyzed by using PFGE with smaI endonuclease.

RESULTS

Of the S. pneumoniae isolates, 23% were intermediately resistant to penicillin. There were no high-level resistant pneumococci. The majority of isolates intermediately resistant to penicillin were of serogroups/serotypes 19, 23, 14 and 1, in descending order of frequency. There were eight major clones in strains intermediately resistant to penicillin. It was seen that serogroups in the 23-valent polysaccharide vaccine, 7-valent, 9-valent, and 11-valent vaccine formulations caused 92%, 75%, 78% and 87% of pneumococcal diseases in our region, respectively.

CONCLUSION

Penicillin resistance in S. pneumoniae is relatively uncommon in Kayseri. All vaccine formulations can prevent the majority of pneumococcal diseases, and there is genetic heterogeneity in intermediately penicillin-resistant pneumococci in this region.

Evolution of Streptococcus pneumoniae serotypes and penicillin susceptibility in Latin America, Sireva-Vigía Group, 1993 to 1999. PAHO Sireva-Vigía Study Group. Pan American Health Organization

BACKGROUND

Since 1993 the Pan American Health Organization has coordinated a surveillance network with the National Reference Laboratories of Argentina, Brazil, Chile, Colombia, Mexico and Uruguay aimed at monitoring capsular types and antimicrobial susceptibility of Streptococcus pneumoniae causing invasive disease in children <6 years of age.

METHODS

The surveillance system included children 6 years of age and younger with invasive disease caused by S. pneumoniae. The identification, capsular typing and susceptibility to penicillin of the isolates were conducted using a common protocol, based on standard methodologies.

RESULTS

By June, 1999, 4,105 invasive pneumococcal isolates had been collected mainly from pneumonia (44.1%) and meningitis (41.1%) cases. Thirteen capsular types accounting for 86.1% of the isolates (14, 6A/6B, 5, 1, 23F, 19F, 18C, 19A, 9V, 7F, 3, 9N and 4) remained the most common types during the surveillance period. Diminished susceptibility to penicillin was detected in 28.6% of the isolates, 17.3% with intermediate and 11.3% with high level resistance. Resistance varied among countries and increased during this period in Argentina, Colombia and Uruguay. Serotypes 14 and 23F accounted for 66.6% of the resistance.

CONCLUSION

These surveillance data clearly demonstrate the potential impact of the introduction of a conjugate vaccine on pneumococcal disease and the need for more judicious use of antibiotics to slow or reverse the development of antimicrobial resistance.

Geographical differences in invasive pneumococcal disease rates and serotype frequency in young children

The development of glycoconjugate vaccines for Streptococcus pneumoniae that are effective in very young children has renewed interest in identification of which among the more than 90 pneumococcal serotypes are most likely to cause invasive pneumococcal disease (IPD). Serotype distribution is thought to vary geographically, even between regions as socioeconomically similar as western Europe and North America. To explain these variations, we note the considerable variation that exists between reported rates of IPD in young children in the USA and west European countries. We postulate that this variation is attributable to different blood-culture rates and practices, and that mild IPD is probably underdiagnosed and under-reported in western Europe. On the basis of a comparison of serotype distributions between the two regions, we also postulate that those serotypes found at similar frequencies in both regions are virulent and rarely cause mild disease. As a result, reported distributions of IPD serotypes, especially when expressed as percentages, might be strongly skewed by the distribution of clinical presentations in a particular study population.

Antibiotic resistance in Streptococcus pneumoniae

Resistance to penicillin and other antibiotics in Streptococcus pneumoniae has emerged in Australia and around the world in the past decade, and appears to be worsening (e.g., rates of penicillin resistance in Australia rose from 1% in 1989 to 25% in 1997). In Australia, the only oral antibiotic able to treat respiratory infections caused by some multiresistant strains is high-dose amoxycillin. If these strains increase in prevalence, then treatment failures for relatively minor infections (e.g., otitis media) are likely to become common, resulting in repeat antibiotic courses or hospitalisation for parenteral therapy. Therapy for meningitis caused by penicillin-sensitive pneumococcal strains remains high-dose benzylpenicillin, but empirical treatment while awaiting culture and sensitivity results is problematic; neither penicillin nor third-generation cephalosporins cover all strains. Therefore, many authorities recommend vancomycin, usually combined with a third-generation cephalosporin, for treating presumptive or proven pneumococcal meningitis pending penicillin-susceptibility results. As almost all readily available oral antibiotics in Australia select for resistant strains of pneumococci, multiresistant strains will increase in prevalence unless unnecessary antibiotic use and prescription volumes are reduced substantially in the next few years.

23-valent pneumococcal polysaccharide vaccine in HIV-1-infected Ugandan adults: double-blind, randomised and placebo controlled trial

BACKGROUND

Infection with Streptococcus pneumoniae is a frequent and serious problem for HIV-immunosuppressed adults. Vaccination is recommended in the USA and Europe, but there are no prospective data that show vaccine efficacy.

METHODS

1392 (937 female) HIV-1-infected adults in Entebbe, Uganda, were enrolled. 697 received 23-valent pneumococcal polysaccharide vaccine and 695 received placebo. The primary endpoint was first event invasive pneumococcal disease. Secondary endpoints included vaccine serogroup-specific invasive disease, all (probable and definite) pneumococcal events, all-cause pneumonia, and death.

FINDINGS

First invasive events occurred in 25 individuals (24 bacteraemias, one pyomyositis), 15 in the vaccine arm and ten in the placebo arm (hazard ratio [HR] 1.47; 95% CI 0.7-3.3). 22 isolates (88%) were of vaccine-specific serogroups with 15 events in the vaccine arm compared with seven in the placebo arm (HR 2.10; 0.9-5.2). All pneumococcal events had a similar distribution (20 vs 14; HR 1.41; 0.7-2.8) though all-cause pneumonia was significantly more frequent in the vaccine arm (40 vs 21; HR 1.89; 1.1-3.2). Mortality was unaffected by vaccination.

INTERPRETATION

23-valent pneumococcal polysaccharide vaccination is ineffective in HIV-1-infected Ugandan adults and probably has little, or no, public health value elsewhere in sub-Saharan Africa. Increased rates of pneumococcal disease in vaccine recipients may necessitate a reappraisal of this intervention in other settings.

Aetiology, outcome, and risk factors for mortality among adults with acute pneumonia in Kenya

BACKGROUND

Despite a substantial disease burden, there is little descriptive epidemiology of acute pneumonia in sub-Saharan Africa. We did this study to define the aetiology of acute pneumonia, to estimate mortality at convalescence, and to analyse mortality risk-factors.

METHODS

We studied 281 Kenyan adults who presented to two public hospitals (one urban and one rural) with acute radiologically confirmed pneumonia during 1994-96. We did blood and lung-aspirate cultures, mycobacterial cultures, serotype-specific pneumococcal antigen detection, and serology for viral and atypical agents.

FINDINGS

Aetiology was defined in 182 (65%) patients. Streptococcus pneumoniae was the most common causative agent, being found in 129 (46%) cases; Mycobacterium tuberculosis was found in 26 (9%). Of 255 patients followed up for at least 3 weeks, 25 (10%) died at a median age of 33 years. In multivariate analyses, risk or protective factors for mortality were age (odds ratio 1.51 per decade [95% CI 1.04-2.19]), unemployment (4.42 [1.21-16.1]), visiting a traditional healer (5.26 [1.67-16.5]), visiting a pharmacy (0.30 [0.10-0.91]), heart rate (1.64 per 10 beats [1.24-2.16]), and herpes labialis (15.4 [2.22-107]). HIV-1 seropositivity, found in 52%, was not associated with mortality. Death or failure to recover after 3 weeks was more common in patients with pneumococci of intermediate resistance to benzylpenicillin, which comprised 28% of pneumococcal isolates, than in those infected with susceptible pneumococci (5.60 [1.33-23.6]).

INTERPRETATION

We suggest that tuberculosis is a sufficiently common cause of acute pneumonia in Kenyan adults to justify routine sputum culture, and that treatment with benzylpenicillin remains appropriate for clinical failure due to M. tuberculosis, intermediate-resistant pneumococci, and other bacterial pathogens. However, interventions restricted to hospital management will fail to decrease mortality associated with socioeconomic, educational, and behavioural factors.

Which pneumococcal serogroups cause the most invasive disease: implications for conjugate vaccine formulation and use, part I

We analyzed >70 recent data sets to compare the serogroups causing invasive pneumococcal disease (IPD) with those represented in conjugate vaccine formulations. Five to 8 and 10-11 serogroups comprise at least 75% of pneumococcal isolates from young children and older children/adults, respectively, in each geographic region. Serogroups in the 7-valent formulation (4, 6, 9, 14, 18, 19, and 23) cause 70%-88% of IPD in young children in the United States and Canada, Oceania, Africa, and Europe, and <65% in Latin America and Asia. Serogroups in the 9-valent formulation (7-valent+1, 5) cause 80%-90% of IPD in each region except Asia (66%). Serogroup 1 accounts for >6% of IPD in each region, including Europe, except the United States and Canada and Oceania. In contrast, several serogroups not found in 7-, 9-, and 11-valent conjugate formulations are significant causes of disease in older children/adults. Nevertheless, each conjugate formulation could prevent a substantial IPD burden in each region and age group.