Genomic Analysis of Group B Streptococcus Carriage Isolates From Botswana Reveals Distinct Local Epidemiology and Identifies Novel Strains.

In pregnant people colonized with group B Streptococcus (GBS) in Botswana, we report the presence/expansion of sequence types 223 and 109, a low rate of erythromycin resistance, and 3 novel sequence types. These data highlight the importance of local epidemiologic studies of GBS, a significant source of neonatal disease.

Evolution of pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine.

Pneumococcal conjugate vaccines reduce the burden of invasive pneumococcal disease, but the sustained effect of these vaccines can be diminished by an increase in disease caused by non-vaccine serotypes. To describe pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine (PCV-13) in July 2012, we performed molecular serotyping of 268 pneumococcal strains isolated from 221 children between 2012 and 2017. The median (interquartile range) age of the children included in this analysis was 6 (3,12) months. Fifty-nine percent of the children had received at least one dose of PCV-13 and 35% were fully vaccinated with PCV-13. While colonization by vaccine serotypes steadily declined following PCV-13 introduction, 25% of strains isolated more than 3 years after vaccine introduction were PCV-13 serotypes. We also observed an increase in colonization by non-vaccine serotypes 21 and 23B, which have been associated with invasive pneumococcal disease and antibiotic resistance in other settings.

Non-diphtheriae Corynebacterium species are associated with decreased risk of pneumococcal colonization during infancy.

Streptococcus pneumoniae (pneumococcus) is a leading cause of severe infections among children and adults. Interactions between commensal microbes in the upper respiratory tract and S. pneumoniae are poorly described. In this study, we sought to identify interspecies interactions that modify the risk of S. pneumoniae colonization during infancy and to describe development of the upper respiratory microbiome during infancy in a sub-Saharan African setting. We collected nasopharyngeal swabs monthly (0-6 months of age) or bimonthly (6-12 months of age) from 179 mother-infant dyads in Botswana. We used 16S ribosomal RNA gene sequencing to characterize the nasopharyngeal microbiome and identified S. pneumoniae colonization using a species-specific PCR assay. We detect S. pneumoniae colonization in 144 (80%) infants at a median age of 71 days and identify a strong negative association between the relative abundance of the bacterial genera Corynebacterium within the infant nasopharyngeal microbiome and the risk of S. pneumoniae colonization. Using in vitro cultivation experiments, we demonstrate growth inhibition of S. pneumoniae by secreted factors from strains of several Corynebacterium species isolated from these infants. Finally, we demonstrate that antibiotic exposures and the winter season are associated with a decline in the relative abundance of Corynebacterium within the nasopharyngeal microbiome, while breastfeeding is associated with an increase in the Corynebacterium relative abundance. Our findings provide novel insights into the interspecies interactions that contribute to colonization resistance to S. pneumoniae and suggest that the nasopharyngeal microbiome may be a previously unrecognized mechanism by which environmental factors influence the risk of pneumococcal infections during childhood. Moreover, this work lays the foundation for future studies seeking to use targeted manipulation of the nasopharyngeal microbiome to prevent infections caused by S. pneumoniae.

Clinical spectrum and prevalence of congenital heart disease in children in Botswana.

BACKGROUND: Reliable data on congenital heart disease (CHD) from diverse settings is important both for planning health systems in each country and to elucidate possible aetiologies of CHD in different settings. There is a lack of data on the clinical spectrum and prevalence of CHD in Botswana. The aim of this study was to describe the clinical spectrum and prevalence of CHD in Botswana. METHODS: This was a retrospective, descriptive, cross-sectional study of all children from birth to 15 years who had had an echocardiogram performed as an in- or out-patient at Princess Marina Hospital (PMH) between 1 January 2010 and 31 December 2012. RESULTS: Of 377 enrollees, 140 (40%) had normal echocardiographs, 170 (45%) had CHD, and 57 (15%) had an acquired lesion. In the CHD patients, median age was 0.9 years (Q1: 0.2, Q3: 4.1) and 85 (50%) were male. Ventricular septal defect (VSD) (29%), patent ductus arteriosus (18%), atrio-ventricular septal defect (AVSD) (10%) and tetralogy of Fallot (TOF) (6%) were the predominant pathologies. VSD was the most common acyanotic lesion and TOF the most common cyanotic lesion. The estimated prevalence of CHD was between 2.8 and 4.95 per 1 000 live births. CONCLUSIONS: The clinical spectrum of CHD in Botswana is similar to that observed in other African countries and in the Western world, with VSD the most common acyanotic lesion and TOF the most common cyanotic lesion. The prevalence of CHD was 2.8-4.95 per 1 000 live births, in keeping with other settings. This is the first study to describe CHD in Botswana, and it aimed to stimulate subsequent studies in this field.

Interpretation of pediatric chest radiographs by non-radiologist clinicians in Botswana using World Health Organization criteria for endpoint pneumonia.

BACKGROUND: In low- and middle-income countries, chest radiographs are most frequently interpreted by non-radiologist clinicians. OBJECTIVE: We examined the reliability of chest radiograph interpretations performed by non-radiologist clinicians in Botswana and conducted an educational intervention aimed at improving chest radiograph interpretation accuracy among non-radiologist clinicians. MATERIALS AND METHODS: We recruited non-radiologist clinicians at a referral hospital in Gaborone, Botswana, to interpret de-identified chest radiographs for children with clinical pneumonia. We compared their interpretations with those of two board-certified pediatric radiologists in the United States. We evaluated associations between level of medical training and the accuracy of chest radiograph findings between groups, using logistic regression and kappa statistics. We then developed an in-person training intervention led by a pediatric radiologist. We asked participants to interpret 20 radiographs before and immediately after the intervention, and we compared their responses to those of the facilitating radiologist. For both objectives, our primary outcome was the identification of primary endpoint pneumonia, defined by the World Health Organization as presence of endpoint consolidation or endpoint effusion. RESULTS: Twenty-two clinicians interpreted chest radiographs in the primary objective; there were no significant associations between level of training and correct identification of endpoint pneumonia; concordance between respondents and radiologists was moderate (κ=0.43). After the training intervention, participants improved agreement with the facilitating radiologist for endpoint pneumonia from fair to moderate (κ=0.34 to κ=0.49). CONCLUSION: Non-radiologist clinicians in Botswana do not consistently identify key chest radiographic findings of pneumonia. A targeted training intervention might improve non-radiologist clinicians' ability to interpret chest radiographs.

The stepwise assembly of the neonatal virome is modulated by breastfeeding.

The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which-in some cases-leads to gastrointestinal disorders1-4. Here we show that the assembly of the viral community in neonates takes place in distinct steps. Fluorescent staining of virus-like particles purified from infant meconium or early stool samples shows few or no particles, but by one month of life particle numbers increase to 109 per gram, and these numbers seem to persist throughout life5-7. We investigated the origin of these viral populations using shotgun metagenomic sequencing of virus-enriched preparations and whole microbial communities, followed by targeted microbiological analyses. Results indicate that, early after birth, pioneer bacteria colonize the infant gut and by one month prophages induced from these bacteria provide the predominant population of virus-like particles. By four months of life, identifiable viruses that replicate in human cells become more prominent. Multiple human viruses were more abundant in stool samples from babies who were exclusively fed on formula milk compared with those fed partially or fully on breast milk, paralleling reports that breast milk can be protective against viral infections8-10. Bacteriophage populations also differed depending on whether or not the infant was breastfed. We show that the colonization of the infant gut is stepwise, first mainly by temperate bacteriophages induced from pioneer bacteria, and later by viruses that replicate in human cells; this second phase is modulated by breastfeeding.

High Rate of Serotype V Streptococcus agalactiae Carriage in Pregnant Women in Botswana.

Maternal rectovaginal colonization is the major risk factor for early-onset neonatal sepsis due to Group B Streptococcus (GBS), a major cause of early life morbidity and mortality. Transmission generally occurs perinatally from colonized mothers to infants. Vaccines targeting a subset of GBS serotypes are under development, but GBS epidemiology remains poorly understood in many African nations. We performed a cross-sectional study of GBS colonization among pregnant women at two sites in Botswana, a country with minimal prior GBS carriage data. We found a rectovaginal colonization rate of 19%, comparable with studies in other regions; however, we also noted a striking predominance of serotype V (> 45% of strains). Although further studies are required to delineate the burden of invasive GBS disease in Botswana and the generalizability of type V epidemiology, these data provide a useful baseline for understanding the potential local impact of GBS prevention strategies, including vaccines.

Pneumococcal Colonization and the Nasopharyngeal Microbiota of Children in Botswana.

BACKGROUND: Nasopharyngeal colonization precedes infections caused by Streptococcus pneumoniae. A more detailed understanding of interactions between S. pneumoniae and the nasopharyngeal microbiota of children could inform strategies to prevent pneumococcal infections. METHODS: We collected nasopharyngeal swabs from children 1 to 23 months of age in Botswana between August 2012 and June 2016. We tested samples for S. pneumoniae and common respiratory viruses using polymerase chain reaction. We sequenced the V3 region of the bacterial 16S ribosomal RNA gene and used random forest models to identify clinical variables and bacterial genera that were associated with pneumococcal colonization. RESULTS: Mean age of the 170 children included in this study was 8.3 months. Ninety-six (56%) children were colonized with S. pneumoniae. Pneumococcal colonization was associated with older age (P = 0.0001), a lack of electricity in the home (P = 0.02) and household use of wood as a cooking fuel (P = 0.002). Upper respiratory symptoms were more frequent in children with S. pneumoniae colonization (60% vs. 32%; P = 0.001). Adjusting for age, nasopharyngeal microbiota composition differed in colonized and noncolonized children (P = 0.001). S. pneumoniae colonization was associated with a higher relative abundance of Moraxella (P = 0.001) and lower relative abundances of Corynebacterium (P = 0.001) and Staphylococcus (P = 0.03). A decision tree model containing the relative abundances of bacterial genera had 81% sensitivity and 85% specificity for the determination of S. pneumoniae colonization status. CONCLUSIONS: S. pneumoniae colonization is associated with characteristic alterations of the nasopharyngeal microbiota of children. Prospective studies should determine if nasopharyngeal microbial composition alters the risk of pneumococcal colonization and thus could be modified as a novel pneumonia prevention strategy.

The Nasopharyngeal Microbiota of Children With Respiratory Infections in Botswana.

BACKGROUND: Nearly half of child pneumonia deaths occur in sub-Saharan Africa. Microbial communities in the nasopharynx are a reservoir for pneumonia pathogens and remain poorly described in African children. METHODS: Nasopharyngeal swabs were collected from children with pneumonia (N = 204), children with upper respiratory infection symptoms (N = 55) and healthy children (N = 60) in Botswana between April 2012 and April 2014. We sequenced the V3 region of the bacterial 16S ribosomal RNA gene and used partitioning around medoids to cluster samples into microbiota biotypes. We then used multivariable logistic regression to examine whether microbiota biotypes were associated with pneumonia and upper respiratory infection symptoms. RESULTS: Mean ages of children with pneumonia, children with upper respiratory infection symptoms and healthy children were 8.2, 11.4 and 8.0 months, respectively. Clustering of nasopharyngeal microbiota identified 5 distinct biotypes: Corynebacterium/Dolosigranulum-dominant (23%), Haemophilus-dominant (11%), Moraxella-dominant (24%), Staphylococcus-dominant (13%) and Streptococcus-dominant (28%). The Haemophilus-dominant [odds ratio (OR): 13.55; 95% confidence interval (CI): 2.10-87.26], the Staphylococcus-dominant (OR: 8.27; 95% CI: 2.13-32.14) and the Streptococcus-dominant (OR: 39.97; 95% CI: 6.63-241.00) biotypes were associated with pneumonia. The Moraxella-dominant (OR: 3.71; 95% CI: 1.09-12.64) and Streptococcus-dominant (OR: 12.26; 95% CI: 1.81-83.06) biotypes were associated with upper respiratory infection symptoms. In children with pneumonia, HIV infection was associated with a lower relative abundance of Dolosigranulum (P = 0.03). CONCLUSIONS: Pneumonia and upper respiratory infection symptoms are associated with distinct nasopharyngeal microbiota biotypes in African children. A lower abundance of the commensal genus Dolosigranulum may contribute to the higher pneumonia risk of HIV-infected children.