Long-term Impact of Oral Azithromycin Taken by Gambian Women During Labor on Prevalence and Antibiotic Susceptibility of Streptococcus pneumoniae and Staphylococcus aureus in Their Infants: Follow-up of a Randomized Clinical Trial

Single-dose oral azithromycin prophylaxis in planned vaginal delivery for sepsis prevention: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

The use of oral azithromycin (AZI) as a preventive measure against postpartum infections of planned vaginal births has garnered a lot of interest in recent years and has been the subject of many randomized controlled trials (RCTs). However, the results from these trials have not been consistent. Therefore, we aim to perform a systematic review and meta-analysis to determine whether the use of a single-dose of oral AZI is clinically significant.

METHODS

We systematically searched PubMed, Embase, and Cochrane Central for RCTs from May to June 2023, comparing a single dose of oral AZI with placebo in patients undergoing planned vaginal delivery at a minimum of 28 weeks of gestational age. The main outcomes were puerperal and neonatal sepsis. Statistical analyses were performed using Review Manager 5.4.1 (Cochrane Collaboration). Heterogeneity was assessed with I2 statistics.

RESULTS

Four RCTs were included (mothers, n = 42 235; newborns n = 42 492). Approximately 49.8% of mothers received a single dose of oral AZI for sepsis prophylaxis. Compared with placebo, AZI significantly reduced the incidence of puerperal sepsis (risk ratio [RR], 0.65 [95% confidence interval (CI), 0.55-0.77]; P < 0.001), mastitis or breast abscess (RR, 0.58 [95% CI, 0.42-0.79]; P < 0.001), endometritis (RR, 0.65 [95% CI, 0.54-0.77]; P < 0.001), wound infection (RR, 0.81 [95% CI, 0.69-0.96]; P = 0.013), infection rate (RR, 0.62 [95% CI, 0.51-0.76]; P < 0.001), and fever (RR, 0.50 [95% CI, 0.28-0.89]; P = 0.018) in mothers. No statistically significant differences were identified between groups regarding maternal all-cause mortality and the use of prescribed postpartum antibiotics. Similarly, no statistical differences were noted in the neonatal group regarding sepsis, infection rate, and all-cause mortality.

CONCLUSION

AZI appears to be an effective preventive measure against many postpartum infections in mothers but a substantial impact on neonatal outcomes has not yet been conclusively observed.

Global epidemiology of asymptomatic colonisation of methicillin-resistant Staphylococcus aureus in the upper respiratory tract of young children: a systematic review and meta-analysis

OBJECTIVE

To estimate the global prevalence of asymptomatic colonisation, and determine the associated risk factors, antibiotic resistance and genotypes of methicillin-resistant Staphylococcus aureus (MRSA) in the upper respiratory tract of young children.

DESIGN

Four bibliometric databases were searched for publications between 2010 and 2022 according to the protocol registered in PROSPERO. Cross-sectional or cohort studies describing the prevalence of asymptomatic colonisation of S. aureus and MRSA in young children were included. Data extraction and analysis were carried out by two reviewers independently according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. Pooled prevalence was estimated using a random effects model.

SETTING AND STUDIES

We included studies where children without respiratory tract infection or Staphylococcal infection were recruited from the community, children's institutions (ie, nurseries, kindergartens, daycare centres and preschools) and healthcare centre visits and assessed for asymptomatic colonisation with S. aureus and MRSA.

MAIN OUTCOME MEASURES

The pooled prevalence of asymptomatic colonisation of S. aureus and MRSA of young children globally.

RESULTS

In this systematic review and meta-analysis of 21 416 young children, the pooled global prevalence of asymptomatic S. aureus colonisation was 25.1% (95% CI 21.4 to 28.8) and MRSA colonisation was 3.4% (95% CI 2.8 to 4.1). The clones of MRSA strains included healthcare-associated MRSA, community-associated MRSA and livestock-associated MRSA.

CONCLUSION

This study provides evidence of increased MRSA colonisation globally among young children, underlining the critical role of asymptomatic carriers in MRSA transmission and the need for control measures.

PROSPERO REGISTRATION NUMBER

CRD 42022328385.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Azithromycin to Prevent Sepsis or Death in Women Planning a Vaginal Birth

BACKGROUND

The use of azithromycin reduces maternal infection in women during unplanned cesarean delivery, but its effect on those with planned vaginal delivery is unknown. Data are needed on whether an intrapartum oral dose of azithromycin would reduce maternal and offspring sepsis or death.

METHODS

In this multicountry, placebo-controlled, randomized trial, we assigned women who were in labor at 28 weeks' gestation or more and who were planning a vaginal delivery to receive a single 2-g oral dose of azithromycin or placebo. The two primary outcomes were a composite of maternal sepsis or death and a composite of stillbirth or neonatal death or sepsis. During an interim analysis, the data and safety monitoring committee recommended stopping the trial for maternal benefit.

RESULTS

A total of 29,278 women underwent randomization. The incidence of maternal sepsis or death was lower in the azithromycin group than in the placebo group (1.6% vs. 2.4%), with a relative risk of 0.67 (95% confidence interval [CI], 0.56 to 0.79; P<0.001), but the incidence of stillbirth or neonatal death or sepsis was similar (10.5% vs. 10.3%), with a relative risk of 1.02 (95% CI, 0.95 to 1.09; P = 0.56). The difference in the maternal primary outcome appeared to be driven mainly by the incidence of sepsis (1.5% in the azithromycin group and 2.3% in the placebo group), with a relative risk of 0.65 (95% CI, 0.55 to 0.77); the incidence of death from any cause was 0.1% in the two groups (relative risk, 1.23; 95% CI, 0.51 to 2.97). Neonatal sepsis occurred in 9.8% and 9.6% of the infants, respectively (relative risk, 1.03; 95% CI, 0.96 to 1.10). The incidence of stillbirth was 0.4% in the two groups (relative risk, 1.06; 95% CI, 0.74 to 1.53); neonatal death within 4 weeks after birth occurred in 1.5% in both groups (relative risk, 1.03; 95% CI, 0.86 to 1.24). Azithromycin was not associated with a higher incidence in adverse events.

CONCLUSIONS

Among women planning a vaginal delivery, a single oral dose of azithromycin resulted in a significantly lower risk of maternal sepsis or death than placebo but had little effect on newborn sepsis or death. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; A-PLUS ClinicalTrials.gov number, NCT03871491.).

Prevention of young infant infections using oral azithromycin in labour in Fiji (Bulabula MaPei): study protocol of a randomised control trial

INTRODUCTION

Infections are a leading cause of neonatal mortality globally and can be transmitted from mother-to-child vertically or horizontally. Fiji has higher rates of serious neonatal infections and infant skin and soft tissue infections (SSTIs) than high-income countries. Research from the Gambia found that a single dose of oral azithromycin in labour decreased bacterial carriage and infections in mothers and infants, particularly infant skin infections. The Bulabula MaPei clinical trial evaluates the safety and efficacy of a single dose of azithromycin in labour in reducing the incidence of maternal and infant SSTIs and other infections and the impact on bacterial carriage. It will also describe the effect of azithromycin on antimicrobial (AMR) resistance, the maternal and infant microbiome, and infant dysbiosis.

METHODS AND ANALYSIS

We are conducting a blinded, placebo-controlled randomised clinical trial administering 2 g of oral azithromycin, or placebo, given to healthy, pregnant women (≥18 years) in labour in Suva, Fiji. The primary outcome is the cumulative incidence of SSTIs in infants by 3 months of age. Secondary outcomes include the incidence of other infant and maternal infections, and safety and tolerability of azithromycin in mother and infant. Following informed consent, 2110 pregnant women will be randomised in a 1:1 ratio, with all study staff and participants masked to group allocation. Mother/infant pairs will be followed up for 12 months over six visits collecting clinical data on infections, antimicrobial use, safety and anthropometrics, in addition to nasopharyngeal, oropharyngeal, rectovaginal and vaginal swabs, maternal breastmilk and infant stool samples, in order to compare bacterial carriage, AMR rates and microbiome. Recruitment for Bulabula MaPei started in June 2019.

ETHICS AND DISSEMINATION

This trial was approved and is being conducted according to the protocol approved by The Royal Children's Hospital Human Research Ethics Committee, Australia, and the Fiji National Health Research and Ethics Review Committee. The findings of this study will be disseminated in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

NCT03925480.

Effect of intra-partum azithromycin on the development of the infant nasopharyngeal microbiota: A post hoc analysis of a double-blind randomized trial

Background

Sepsis is a leading cause of neonatal death. Intrapartum azithromycin reduces neonatal nasopharyngeal carriage of potentially pathogenic bacteria, a prerequisite for sepsis. Early antibiotic exposure has been associated with microbiota perturbations with varying effects. This study aims to understand the effect of intrapartum azithromycin intervention on the developing nasopharyngeal microbiota of the child.

Methods

Using 16S rRNA gene sequencing, we analysed the microbiota of 343 nasopharyngeal samples collected from birth to 12 months from 109 healthy infants selected from a double-blind randomized placebo-controlled clinical trial conducted in the Gambia (PregnAnZI-1). In the trial, 829 women were given 2g oral azithromycin or placebo (1:1) during labour with the objective of reducing bacterial carriage in mother and child during the neonatal period. The post-hoc analysis presented here assessed the effect of the intervention on the child nasopharyngeal microbiota development.

Findings

55 children were from mothers given azithromycin and 54 from mothers given placebo. Comparing arms, we found an increase in alpha-diversity at day-6 (p = 0·018), and a significant effect on overall microbiota composition at days 6 and 28 (R² = 4.4%, q = 0·007 and R² = 2.3%, q = 0·018 respectively). At genus level, we found lower representation of Staphylococcus at day-6 (q = 0·0303) and higher representation of Moraxella at 12 months (q = 0·0443). Unsupervised clustering of samples by microbial community similarity showed different community dynamics between the intervention and placebo arms during the neonatal period.

Interpretation

These results indicate that intrapartum azithromycin caused short-term alterations in the nasopharyngeal microbiota with modest overall effect at 12 months of age. Further exploration of the effects of these variations on microbiome function will give more insight on the potential risks and benefits, for the child, associated with this intervention.

Funding

This work was jointly funded by the Medical Research Council (UK) (MC_EX_MR/J010391/1/MRC), Bill & Melinda Gates Foundation (OPP1196513), and MRCG@LSHTM Doctoral Training Program.

A novel intervention combining supplementary food and infection control measures to improve birth outcomes in undernourished pregnant women in Sierra Leone: A randomized, controlled clinical effectiveness trial

BACKGROUND

Innovations for undernourished pregnant women that improve newborn survival and anthropometry are needed to achieve the Sustainable Development Goals 1 and 3. This study tested the hypothesis that a combination of a nutritious supplementary food and several proven chemotherapeutic interventions to control common infections would increase newborn weight and length in undernourished pregnant women.

METHODS AND FINDINGS

This was a prospective, randomized, controlled clinical effectiveness trial of a ready-to-use supplementary food (RUSF) plus anti-infective therapies compared to standard therapy in undernourished pregnant women in rural Sierra Leone. Women with a mid-upper arm circumference (MUAC) ≤23.0 cm presenting for antenatal care at one of 43 government health clinics in Western Rural Area and Pujehun districts were eligible for participation. Standard of care included a blended corn/soy flour and intermittent preventive treatment for malaria in pregnancy (IPTp). The intervention replaced the blended flour with RUSF and added azithromycin and testing and treatment for vaginal dysbiosis. Since the study involved different foods and testing procedures for the intervention and control groups, no one except the authors conducting the data analyses were blinded. The primary outcome was birth length. Secondary outcomes included maternal weight gain, birth weight, and neonatal survival. Follow-up continued until 6 months postpartum. Modified intention to treat analyses was undertaken. Participants were enrolled and followed up from February 2017 until February 2020. Of the 1,489 women enrolled, 752 were allocated to the intervention and 737 to the standard of care. The median age of these women was 19.5 years, of which 42% were primigravid. Twenty-nine women receiving the intervention and 42 women receiving the standard of care were lost to follow-up before pregnancy outcomes were obtained. There were 687 singleton live births in the intervention group and 657 in the standard of care group. Newborns receiving the intervention were 0.3 cm longer (95% confidence interval (CI) 0.09 to 0.6; p = 0.007) and weighed 70 g more (95% CI 20 to 120; p = 0.005) than those receiving the standard of care. Those women receiving the intervention had greater weekly weight gain (mean difference 40 g; 95% CI 9.70 to 71.0, p = 0.010) than those receiving the standard of care. There were fewer neonatal deaths in the intervention (n = 13; 1.9%) than in the standard of care (n = 28; 4.3%) group (difference 2.4%; 95% CI 0.3 to 4.4), (HR 0.62 95% CI 0.41 to 0.94, p = 0.026). No differences in adverse events or symptoms between the groups was found, and no serious adverse events occurred. Key limitations of the study are lack of gestational age estimates and unblinded administration of the intervention.

CONCLUSIONS

In this study, we observed that the addition of RUSF, azithromycin, more frequent IPTp, and testing/treatment for vaginal dysbiosis in undernourished pregnant women resulted in modest improvements in anthropometric status of mother and child at birth, and a reduction in neonatal death. Implementation of this combined intervention in rural, equatorial Africa may well be an important, practical measure to reduce infant mortality in this context.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03079388.

Impact of mass and systematic antibiotic administration on antibiotic resistance in low- and middle-income countries? A systematic review

Antibiotic consumption is a key driver of antimicrobial resistance (AR), particularly in low- and middle-income countries (LMICs) where risk factors for AR emergence and spread are prevalent. However, the potential contribution of mass drug administration (MDA) and systematic drug administration (SDA) of antibiotics to AR spread is unknown. We conducted a systematic review to provide an overview of MDA/SDA in LMICs, including indications, antibiotics used and, if investigated, levels of AR over time. This systematic review is reported in accordance with the PRISMA statement. Of 2438 identified articles, 63 were reviewed: indications for MDA/SDA were various, and targeted populations were particularly vulnerable, including pregnant women, children, human immunodeficiency virus (HIV)-infected populations, and communities in outbreak settings. Available data suggest that MDA/SDA may lead to a significant increase in AR, especially following azithromycin administration. However, only 40% of studies evaluated AR. Integrative approaches that evaluate AR in addition to clinical outcomes are needed to understand the consequences of MDA/SDA implementation, combined with standardised AR surveillance for timely detection of AR emergence.

Impact of Intrapartum Oral Azithromycin on the Acquired Macrolide Resistome of Infants' Nasopharynx: A Randomized Controlled Trial

In a post hoc analysis of samples from an intrapartum azithromycin randomized clinical trial, we found that children whose mothers had been treated with the drug had higher prevalence of macrolide-resistance genes msr(A) and ermC at 28 days but not at 12 months. The 2 genes were positively associated in the nasopharynx.

CLINICAL TRIALS REGISTRATION

NCT1800942.

Genomic investigation of Staphylococcus aureus recovered from Gambian women and newborns following an oral dose of intra-partum azithromycin

BACKGROUND

Oral azithromycin given during labour reduces carriage of bacteria responsible for neonatal sepsis, including Staphylococcus aureus. However, there is concern that this may promote drug resistance.

OBJECTIVES

Here, we combine genomic and epidemiological data on S. aureus isolated from mothers and babies in a randomized intra-partum azithromycin trial (PregnAnZI) to describe bacterial population dynamics and resistance mechanisms.

METHODS

Participants from both arms of the trial, who carried S. aureus in day 3 and day 28 samples post-intervention, were included. Sixty-six S. aureus isolates (from 7 mothers and 10 babies) underwent comparative genome analyses and the data were then combined with epidemiological data. Trial registration (main trial): ClinicalTrials.gov Identifier NCT01800942.

RESULTS

Seven S. aureus STs were identified, with ST5 dominant (n = 40, 61.0%), followed by ST15 (n = 11, 17.0%). ST5 predominated in the placebo arm (73.0% versus 49.0%, P = 0.039) and ST15 in the azithromycin arm (27.0% versus 6.0%, P = 0.022). In azithromycin-resistant isolates, msr(A) was the main macrolide resistance gene (n = 36, 80%). Ten study participants, from both trial arms, acquired azithromycin-resistant S. aureus after initially harbouring a susceptible isolate. In nine (90%) of these cases, the acquired clone was an msr(A)-containing ST5 S. aureus. Long-read sequencing demonstrated that in ST5, msr(A) was found on an MDR plasmid.

CONCLUSIONS

Our data reveal in this Gambian population the presence of a dominant clone of S. aureus harbouring plasmid-encoded azithromycin resistance, which was acquired by participants in both arms of the study. Understanding these resistance dynamics is crucial to defining the public health drug resistance impacts of azithromycin prophylaxis given during labour in Africa.

Structural insights into the substrate specificity of SP_0149, the substrate-binding protein of a methionine ABC transporter from Streptococcus pneumoniae

Successful pathogenesis is a cumulative effect of the virulence factors of a pathogen and its capability to efficiently utilize the available nutrients from the host. Streptococcus pneumoniae, a Gram-positive opportunistic pathogen, may either reside asymptomatically as a nasopharyngeal commensal inside the human host or cause lethal diseases, including pneumonia, meningitis and sepsis. S. pneumoniae is known to acquire methionine (Met) from its host through a Met importer. Here, the crystal structure of the substrate-binding protein (SBP; SP_0149) of an ABC importer with Met bound is reported at a resolution of 1.95 Å. The three-dimensional structure of SBP shows that it is composed of two distinct domains, each consisting of a mixed β-sheet flanked by helices. The substrate, Met, is bound in the central part of the interface between the two domains. The overall structure of SP_0149 resembles those of SBPs from other reported bacterial Met and Gly-Met dipeptide transporters. However, a detailed analysis of these structures shows notable variations in the amino-acid composition of the substrate-binding pockets of the SP_0149-Met and GmpC-Gly-Met structures. In particular, SP_0149 harbors Thr212 and Tyr114, whereas the corresponding residues in GmpC are Gly and Val. This difference is likely to be the underlying basis for their differential substrate specificity. In summary, the structure of the SP_0149-Met complex provides insights into the transport function of SP_0149 and its interactions with methionine. It opens up avenues for the rational design of inhibitors of SP_0149 through a structure-mediated approach.