Background The continuing impact of pneumococcal conjugate vaccines (PCVs) in regions with high pneumococcal transmission is threatened by the persistence of vaccine serotypes (VT) and the emergence of non-vaccine serotypes (NVT). Methods In 2016, we conducted a cross-sectional carriage survey (CSS5) in a community where PCV7 was first introduced in 2006 during a cluster randomised trial conducted before nationwide introduction of PCV7 (2009) and PCV13 (2011). We estimated the prevalence of PCV13 VT and NVT by age and compared these to earlier surveys before (CSS0), during (CSS1-3), and after the trial but before PCV13 (CSS4). Genomic analysis was conducted for the non-typeable pneumococci. Results The prevalence of PCV13 VT carriage decreased during the 10 years between CSS0 and CSS5 across all age groups (67·6% to 13·5%, p<0.001; 59·8% to 14·4%, p<0.001; 43·1% to 17·9%, p<0.001; and 24·0% to 5·1%, p<0.001 in <2, 2-4, 5-14 and ≥15 years respectively). However, there was no difference between CSS4 and CSS5 in children ≥2 years and adults (children < 2 years, no data). The prevalence of PCV13 NVT increased between CSS0 and CSS5 for children <2 years but decreased in older children and adults. In CSS5, serotypes 3, 6A and 19F were the most common VT and non-typeable isolates, the most common NVT. Among non-typeable isolates, 73·0% lost the ability to express a capsule. Of these, 70·8% were from a VT background. Conclusions The decrease in PCV13 VT that has occurred since the introduction of PCV13 appears to have plateaued. Significant carriage of these serotypes remains in all age groups.

BackgroundIn West Africa, penicillin, macrolide and lincosamide resistance among beta-haemolytic streptococci (BHS) isolates has rarely been described. However, such data are critical to detect and track the emergence of antibiotic resistance.MethodsBeta-haemolytic streptococci were cultured from clinical specimens from patients attending the clinic at the Medical Research Council Unit The Gambia (n = 217) and kept at −70 °C. Of these, 186 were revived and tested for penicillin susceptibility by disc diffusion and E-test methods, and the D-test for determination of constitutive and inducible macrolide–lincosamide (MLSB) resistance phenotypes.ResultsThe majority of BHS isolates from infections were group A streptococci (GAS) (126/186, 67.7%). Of these, 16% were from invasive disease (30/186). Other BHS isolated included lancefield groups B (19, 10.2%); C (9/186, 4.8%), D (3/186, 1.6%), F (5/186, 2.7%), G (16/186, 8.6%) and non-typeable (8/186, 4.3%). Prevalence of BHS isolated from blood cultures ranges from 0% (2005) to 0.5% (2010). Most (85, 45.7%) of the isolates were from wound infections. Of the 186 BHS isolates, none was resistant to penicillin and 14 (6.1%) were resistant to erythromycin. Of these, 8 (4.3%) demonstrated constitutive MLSB resistance, and 5 (2.7%) were inducible MLSB resistant. All the inducible MLSB isolates were GAS, and majority of the constitutive MLSB isolates (6/8, 75.0%) were non-GAS.ConclusionsBeta-haemolytic streptococci, predominantly GAS are associated with a wide range of infections in The Gambia. It is reassuring that macrolide and lincosamide resistance is relatively low. However, monitoring of MLSB resistance is necessary with the global spread of resistant BHS strains.

IntroductionUnderstanding mother-to-infant transmission of Group B Streptococcus (GBS) is vital to the prevention and control of GBS disease. We investigated the transmission and phylogenetic relationships of mothers colonised by GBS and their infants in a peri-urban setting in The Gambia. MethodsWe collected nasopharyngeal swabs from 35 mother-infant dyads at weekly intervals from birth until six weeks post-partum. GBS was isolated by conventional microbiology techniques. Whole-genome sequencing was performed on GBS isolates from one motherinfant dyad (dyad 17). ResultsWe recovered 85 GBS isolates from the 245 nasopharyngeal swabs. GBS was isolated from 16.33% and 18.37% of sampled mothers and infants, respectively. In 87% of cultured swabs, the culture status of an infant agreed with that of the mother (Kappa p-value <0.001). In dyad 17, phylogenetic analysis revealed within-host strain diversity in the mother and clone to her infant. ConclusionGBS colonisation in mothers presents a significant risk of colonisation in their infants. We confirm vertical transmission from mother to child in dyad 17, accompanied by within-host diversity.

None of the known native actinorhizal species in Turkey, Alnus glutinosa and A. orientalis (Betulaceae), Datisca cannabina (Datiscaceae), Elaeagnus angustifolia and Hippophae rhamnoides (Elaeagnaceae), and the widely-planted exotic Casuarina cunninghamiana (Casuarinaceae), have confirmed records of actinorhizae in Turkey. This study determined the capacity of representative actinorhizal plants in Turkey to form nodules, cluster roots and ectomycorrhizal roots in a typical central Anatolian soil with and without amendment of soil and nodule extracts, as well as in soil from Adana and Izmir. Nodulation was confirmed experimentally for E. angustifolia and C. cunninghamiana in Niğde soil (the latter only with addition Adana or Izmir soil), but only observationally for A. glutinosa during sample collection in Rize. Cluster roots developed strongly in C. cunninghamiana, and likewise ectomycorrhizal roots in Allocasuarina verticillata (included as a reference species) but only to a lesser extent in C. cunninghamiana. The nodulation status of the natives, D. cannabina and H. rhamnoides, remains to be investigated.