Impact of intra-partum azithromycin on carriage of group A streptococcus in the Gambia: a posthoc analysis of a double-blind randomized placebo-controlled trial

Impact of Intrapartum Azithromycin on the Carriage and Antibiotic Resistance of Escherichia coli and Klebsiella pneumoniae in Mothers and Their Newborns: A Substudy of a Randomized, Double-Blind Trial Conducted in The Gambia and Burkina Faso

BACKGROUND

Limited data exist on the effects of intrapartum azithromycin on the prevalence of carriage and antibiotic resistance of Enterobacterales.

METHODS

We conducted a randomized trial in The Gambia and Burkina Faso where women received intrapartum azithromycin (2 g) or placebo. We determined the impact of treatment on the prevalence of carriage and antibiotic resistance of Escherichia coli and Klebsiella pneumoniae by analyzing rectal swabs (RS), nasopharyngeal swabs (NPS), breast milk, and rectovaginal swabs (RVS). Bacteria were isolated microbiologically; antibiotic susceptibility was confirmed with an E-test. Prevalence ratios (PRs) with 95% confidence intervals (CIs) were used for comparison between arms.

RESULTS

In infants, E. coli carriage in RS was lower in the intervention than in the placebo arm at day 6 (63.0% vs 75.2%; PR, 0.84; 95% CI, .75-.95) and day 28 (52.7% vs 70.4%; 0.75; 0.64-0.87) post-intervention. Prevalence of azithromycin-resistant E. coli was higher in the azithromycin arm at day 6 (13.4% vs 3.6%; 3.75; 1.83-7.69) and day 28 (16.4% vs 9.6%; 1.71; 1.05-2.79). For K. pneumoniae, carriage in RS was higher in the intervention than in the placebo arm at day 6 (49.6% vs 37.2%, 1.33; 1.08-1.64) and day 28 (53.6% vs 32.9%, 1.63; 1.31-2.03). Prevalence of azithromycin-resistant K. pneumoniae was higher in the azithromycin arm at day 28 (7.3% vs 2.1%; 3.49; 1.30-9.37). No differences were observed for other sample types.

CONCLUSIONS

Intrapartum azithromycin decreased E. coli carriage but increased both K. pneumoniae carriage and azithromycin resistance in both bacteria. These data need to be considered together with efficacy results to balance the potential short- and long-term impact of the intervention. Clinical Trials Registration.  www.clinicaltrials.gov: NCT03199547.

Streptococcus dysgalactiae subsp. equisimilis infection and its intersection with Streptococcus pyogenes

SUMMARYStreptococcus dysgalactiae subsp. equisimilis (SDSE) is an increasingly recognized cause of disease in humans. Disease manifestations range from non-invasive superficial skin and soft tissue infections to life-threatening streptococcal toxic shock syndrome and necrotizing fasciitis. Invasive disease is usually associated with co-morbidities, immunosuppression, and advancing age. The crude incidence of invasive disease approaches that of the closely related pathogen, Streptococcus pyogenes. Genomic epidemiology using whole-genome sequencing has revealed important insights into global SDSE population dynamics including emerging lineages and spread of anti-microbial resistance. It has also complemented observations of overlapping pathobiology between SDSE and S. pyogenes, including shared virulence factors and mobile gene content, potentially underlying shared pathogen phenotypes. This review provides an overview of the clinical and genomic epidemiology, disease manifestations, treatment, and virulence determinants of human infections with SDSE with a particular focus on its overlap with S. pyogenes. In doing so, we highlight the importance of understanding the overlap of SDSE and S. pyogenes to inform surveillance and disease control strategies.

PeRinatal, neOnatal, and Maternal OuTcomEs with azithromycin prophylaxis in pregnancy and labour (PROMOTE-PROPHYLAXIS): systematic review and meta-analysis

Background

Initial randomised controlled trials (RCTs) showed that prophylactic azithromycin in pregnant women improved maternal and neonatal outcomes; however, the recent evidence did not show any benefit to neonatal survival. There is conflicting evidence over the role of azithromycin prophylaxis in antenatal and intrapartum periods. We explored whether azithromycin prophylaxis in pregnant women improves maternal and neonatal outcomes.

Methods

For this systematic review and meta-analysis registered on PROSPERO [CRD42023411093], we searched seven databases (PubMed, Scopus, Embase, Cochrane Library, EBSCOHost, ProQuest, and Web of Science) and clinical trial registries until 04/23/2024, for RCTs evaluating antenatal/intrapartum azithromycin prophylaxis against placebo/routine care in pregnant women. The primary outcome was neonatal mortality. Intrapartum and antenatal administration were assessed separately. We used random-effects meta-analysis. The risk of bias was assessed using the Cochrane RoB 2 tool. The GRADE approach was used to evaluate the certainty of the evidence.

Findings

Screening 2161 records retrieved 20 RCTs (56,381 participants). Intrapartum azithromycin may make little or no difference to neonatal mortality [5 RCTs, 44,436 participants; Risk Ratio (RR): 1.02, 95% CI 0.86-1.20, I 2  = 0%, very low certainty], and maternal mortality [3 RCTs, 44,131 participants, RR: 1.26, 0.65-2.42, I 2  = 0%, low certainty]. Similarly, antenatal azithromycin may have little or no effect on neonatal mortality [3 RCTs; 5304 participants; RR: 0.74, 0.35-1.56, I 2  = 43%, very-low certainty] and maternal mortality [3 RCTs; 8167 participants RR: 1.62, 0.67-3.91, I 2  = 0%, low certainty]. There is no data on long-term adverse outcomes and antimicrobial resistance.

Interpretation

Low to very low certainty evidence suggests that intrapartum or antenatal azithromycin prophylaxis in pregnant women might not reduce maternal or neonatal mortality.

Funding

None.

Inter-species gene flow drives ongoing evolution of Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of human infection with invasive disease incidence and clinical manifestations comparable to the closely related species, Streptococcus pyogenes. Through systematic genomic analyses of 501 disseminated SDSE strains, we demonstrate extensive overlap between the genomes of SDSE and S. pyogenes. More than 75% of core genes are shared between the two species with one third demonstrating evidence of cross-species recombination. Twenty-five percent of mobile genetic element (MGE) clusters and 16 of 55 SDSE MGE insertion regions were shared across species. Assessing potential cross-protection from leading S. pyogenes vaccine candidates on SDSE, 12/34 preclinical vaccine antigen genes were shown to be present in >99% of isolates of both species. Relevant to possible vaccine evasion, six vaccine candidate genes demonstrated evidence of inter-species recombination. These findings demonstrate previously unappreciated levels of genomic overlap between these closely related pathogens with implications for streptococcal pathobiology, disease surveillance and prevention.