Disease burden and antimicrobial resistance of invasive group B streptococcus among infants in China: a protocol for a national prospective observational study

Distributions of candidate vaccine Targets, virulence Factors, and resistance features of invasive group B Streptococcus using Whole-Genome Sequencing: A Multicenter, population-based surveillance study

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in young infants worldwide. This study aimed to investigate candidate GBS vaccine targets, virulence factors, and antimicrobial resistance determinants.

METHODS

We used whole-genome sequencing to characterize invasive GBS isolates from infants < 3 months of age obtained from a multicenter population-based study conducted from 2015 to 2021 in China.

RESULTS

Overall, seven serotypes were detected from 278 GBS isolates, four (Ia, Ib, III, V) of which accounted for 97.8 %. We detected 30 sequence types (including 10 novel types) that were grouped into six clonal complexes (CCs: CC1, CC10, CC17, CC19, CC23 and CC651); three novel ST groups in CC17 were detected, and the rate of CC17, considered a hyperinvasive neonatal clone complex, was attached to 40.6 % (113/278). A total of 98.9 % (275/278) of isolates harbored at least one alpha-like protein gene. All GBS isolates contained at least one of three pilus backbone determinants and the pilus types PI-2b and PI-1 + PI-2a accounted for 79.8 % of the isolates. The 112 serotype III/CC17 GBS isolates were all positive for hvgA. Most of the isolates (75.2 %) were positive for serine-rich repeat glycoprotein determinants (srr1or srr2). Almost all isolates possessed cfb (99.6 %), c1IE (100 %), lmb (95.3 %) or pavA (100 %) gene. Seventy-seven percent of isolates harboured more than three antimicrobial resistance genes with 28.4 % (79/278) gyrA quinoloneresistancedeterminants mutation, 83.8 % (233/278) carrying tet cluster genes and 77.3 % (215/278) carrying erm genes which mediated fluoroquinolone, tetracycline and clindamycin resistance, respectively."

CONCLUSIONS

The findings from this large whole-genome sequence of GBS isolates establish important baseline data required for further surveillance and evaluating the impact of future vaccine candidates.

Antibiotic resistance genes and molecular typing of Streptococcus agalactiae isolated from pregnant women

BACKGROUND

The antibiotic resistance of genital tract colonizing Streptococcus agalactiae in pregnant women is increasing. We aimed to determine the antibiotic resistance genes of different clonal types of this bacterium in pregnant women.

METHODS

Four hundred twenty non-repeated vaginal and rectal specimens were collected from pregnant women and were transferred to the laboratory using Todd Hewitt Broth. The samples were cultured on a selective medium, and the grown bacteria were identified by standard microbiological and biochemical tests. Antimicrobial resistance pattern and inducible clindamycin resistance of the isolates were determined using the disk agar diffusion method. The genomic DNAs of S. agalactiae strains were extracted using an extraction kit, and the antibiotic resistance genes and RAPD types were detected using the PCR method.

RESULTS

The average age of the participants was 30.74 ± 5.25 years. There was a significant relationship between the weeks of pregnancy and the number of positive bacterial cultures (P-value < 0.05). Moreover, 31 pregnant women had a history of abortion, and 18 had a history of membrane rupture. Among 420 specimens, 106 S. agalactiae isolates were detected. The highest antibiotic resistance rate was found against tetracycline (94.33%), and all isolates were susceptible to linezolid. Moreover, 15, 15, 42, and 7 isolates showed an iMLS_B, M-, cMLS_B, and L-phenotype. The ermB was the most prevalent resistance gene in the present study, while 38 (35.84%), 8 (7.54%), 79 (74.52%), 37 (34.9%), and 20 (18.86%) isolates were contained the ermTR, mefA/E, tetM, tetO, and aphA3 gene, respectively.

CONCLUSIONS

The high-level antibiotic resistance and prevalence of resistance genes may be due to the arbitrarily use, livestock industry consumption, and the preventive use of antibiotics in pregnant women. Thus, the need to re-considering this problem seems to be necessary.

Antimicrobial Resistance and Virulence Genes of Streptococcus Agalactiae Isolated from Mastitis Milk Samples in China

Introduction

Streptococcus agalactiae is an important zoonotic pathogen that affects milk production and quality and poses a threat to public health. Treatment of infections with this bacterium exploits antimicrobials, to which the resistance of S. agalactiae is a growing problem. Addressing the possibility of a correlation between this pathogen's genetic factors for antimicrobial resistance and virulence, this study attempted to identify the relevant genes.

Material and Methods

Antimicrobial resistance of S. agalactiae isolated from 497 Chinese bovine mastitic milk samples was detected by the broth microdilution method. Eight drug resistance genes and eleven virulence genes were detected using PCR.

Results

Streptococcus agalactiae was 100% susceptible to rifampicin and vancomycin, 93.33% susceptible to sulfisoxazole and sulfamethoxazole, but 100% resistant to ≥3 of the 16 antimicrobial agents, thereby being multidrug resistant, with resistance to oxacillin, tetracycline, erythromycin, clindamycin, and gentamicin being common. The ermB, ermA and lnuA genes were carried by 73.33%, 66.67% and 60.00% of the strains, respectively. The carriage rates of the glnA, clyE, hylB, bibA, iagA, and fbsA virulence genes were greater than 40%, lmb and bac were not observed in any strain, and glnA+hylB+bibA+iagA+fbsA+clyE combined virulence gene patterns were the most commonly detected.

Conclusion

Antimicrobial resistance of S. agalactiae is still a great concern for cattle health in China, and multidrug resistance coupled with the high positive rates of this bacterium's strains for virulence genes indicates the importance of S. agalactiae surveillance and susceptibility tests.

Antimicrobial resistance in colonizing group B Streptococcus among pregnant women from a hospital in Vietnam

Few studies have been conducted on group B Streptococcus (GBS) in Vietnam. We determined the GBS colonization and antimicrobial resistance vaginal-rectal profile of 3863 Vietnamese pregnant women over 5 years. Maternal GBS colonization was characterized by antibiotic susceptibility. Overall, the GBS colonization rate was 8.02% (95% CI: 7.20-8.94%). Compared to sampling ≥ 35 weeks of gestation, the GBS colonization rate was statistically higher (p = 0.004) with sampling < 35 weeks. Among 272 antimicrobial susceptibility testing isolates, all were susceptible to ampicillin, penicillin, ceftriaxone, cefotaxime, vancomycin, and quinupristin/dalfopristin. Resistance was highest for tetracycline (89.66%), followed by erythromycin (76.23%) and clindamycin (58.21%). Multidrug resistance and resistance to ≥ 6 different antibiotics were 60.66% and 8.82%, respectively. Resistance to clindamycin but not erythromycin (L phenotype) was 2.2%. The clindamycin resistance rate was significantly increased (p = 0.005) during the study period. These data demonstrate a low rate of maternal GBS colonization. The high rate of erythromycin, clindamycin, and multidrug resistance to GBS that can be transmitted to neonates is an important risk factor to consider. β-lactams continue to be appropriate for first-line treatment and prophylaxis in the study area. Ongoing monitoring should be considered in the future.

Vertical transfer of antibiotics and antibiotic resistant strains across the mother/baby axis

Antibiotic resistance is a health and socioeconomic crisis recognized as a serious threat affecting humans worldwide. Overuse of antibiotics enhances the spread of multidrug-resistant bacteria, causing drug-resistant infections which can be difficult to treat. This resistance, mostly of the acquired type, is thus a major clinical issue. Acquired resistance can occur by horizontal transfer of genes between bacteria (community settings), by vertical transmission that can occur between mother and her offspring at birth and during lactation, or spontaneously due to antibiotic exposure. While there have been multiple studies about the horizontal transfer of antibiotic-resistance genes, not many studies have been conducted to study their vertical transmission. Vertical transmission is of importance as the early bacterial colonization of infants has an impact on their health and immune programming throughout life. This review discusses some possible mechanisms of mother-to-infant transmission of antibiotics and antibiotic-resistant strains and addresses the knowledge gaps for further studies.

Antibiotic Resistance and Molecular Epidemiological Characteristics of Streptococcus agalactiae Isolated from Pregnant Women in Guangzhou, South China

Streptococcus agalactiae colonization in pregnant women can cause postpartum intrauterine infections and life-threatening neonatal infections. To formulate strategies for the prevention and treatment of S. agalactiae infections, we performed a comprehensive analysis of antibiotic resistance and a molecular-based epidemiological investigation of S. agalactiae in this study. Seventy-two S. agalactiae strains, collected from pregnant women, were subjected to antibiotic susceptibility tests; then, the screened erythromycin and clindamycin nonsusceptible isolates were used for macrolides and clindamycin resistance genes detection, respectively. Detection of resistance genes, serotyping, and determination of virulence genes were performed by polymerase chain reaction. The clonal relationships among the colonized strains were evaluated by multilocus sequence typing. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) mass peak analysis was performed to discriminate the specific sequence types (STs). In our study, 69.4% and 47.2% of the strains were nonsusceptible to erythromycin and clindamycin, respectively; the multidrug resistance rate was 66.7%. All erythromycin nonsusceptible strains harbored resistance genes, whereas only 52.9% of the clindamycin nonsusceptible strains possessed the linB gene. Erythromycin resistance was mainly mediated by the ermB or mefA/E genes. Four serotypes were identified, and the most common serotype was serotype III (52.8%), followed by Ib (22.2%), Ia (18.0%), and II (4.2%). All the strains were divided into 18 STs that were assigned to nine clonal complexes. Most of the major STs were distributed into specific serotypes, including ST19/serotype III, ST17/serotype III, ST485/serotype Ia, ST862/serotype III, and ST651/serotype III. Analysis of virulence genes yielded seven clusters, of which bca-cfb-scpB-lmb (61.6%) was the predominant virulence gene cluster. Among all ST strains distributed in this region, only the ST17 strains had a mass peak at 7620 Da. The outcomes of this study are beneficial for the epidemiological comparison of colonized S. agalactiae in different regions and may be helpful for developing the strategies for the prevention of S. agalactiae infection in Guangzhou. Furthermore, our results show that MALDI-TOF MS can be used for the rapid identification of the ST17 strains.

A Solution to Antifolate Resistance in Group B Streptococcus: Untargeted Metabolomics Identifies Human Milk Oligosaccharide-Induced Perturbations That Result in Potentiation of Trimethoprim

Adjuvants can be used to potentiate the function of antibiotics whose efficacy has been reduced by acquired or intrinsic resistance. In the present study, we discovered that human milk oligosaccharides (HMOs) sensitize strains of group B Streptococcus (GBS) to trimethoprim (TMP), an antibiotic to which GBS is intrinsically resistant. Reductions in the MIC of TMP reached as high as 512-fold across a diverse panel of isolates. To better understand HMOs' mechanism of action, we characterized the metabolic response of GBS to HMO treatment using ultrahigh-performance liquid chromatography-high-resolution tandem mass spectrometry (UPLC-HRMS/MS) analysis. These data showed that when challenged by HMOs, GBS undergoes significant perturbations in metabolic pathways related to the biosynthesis and incorporation of macromolecules involved in membrane construction. This study represents reports the metabolic characterization of a cell that is perturbed by HMOs.IMPORTANCE Group B Streptococcus is an important human pathogen that causes serious infections during pregnancy which can lead to chorioamnionitis, funisitis, premature rupture of gestational membranes, preterm birth, neonatal sepsis, and death. GBS is evolving antimicrobial resistance mechanisms, and the work presented in this paper provides evidence that prebiotics such as human milk oligosaccharides can act as adjuvants to restore the utility of antibiotics.

Incidence, Bacterial Profiles, And Antimicrobial Resistance Of Culture-Proven Neonatal Sepsis In South China

Background

Neonatal sepsis (NS) is one of the leading causes of infant morbidity and mortality, but little is known about pathogen incidence and distribution in China.

Methods

In this retrospective study (January 2012 to December 2016), culture-proven cases aged less than 28 days with diagnosed NS in the Guangzhou Women and Children’s Medical Center, South China, were analyzed for pathogen incidence and antimicrobial resistance.

Results

A total of 620 isolates were identified from 597 NS cases. Gram-negative bacteria (n=371, 59.8%) dominated over Gram-positive bacteria (n=218, 35.2%) and fungi (n=30, 4.8%). Klebsiella pneumoniae (21.9%), Escherichia coli (21.9%), group B Streptococcus (GBS, 13.2%), and Staphylococcus aureus (6.8%) were the four most predominant pathogens. In early-onset sepsis (EOS), GBS (30.0%) and E. coli (20.0%) were dominant, whereas in late-onset sepsis (LOS), K. pneumoniae (25.6%) and E. coli (22.4%) were dominant. E. coli (25.2%) and GBS (17.7%) were the most frequently isolated from term patients, whereas K. pneumoniae was the most frequently isolated from preterm patients (34.9%). Of the infected infants, 9.5% died from sepsis, most commonly by E. coli infection (16.2%). Among 91,215 live births (LBs) delivered in the study hospital (2012–2016), 252 infants developed sepsis infection (2.76 per 1000 LBs, 95% CI 2.4–3.1), including EOS (0.78 per 1000 LBs) and LOS (2.13 per 1000 LBs). All GBS isolates were susceptible to β-lactam antibiotics, and S. aureus, including methicillin-resistant isolates, were susceptible to vancomycin. An extended-spectrum β-lactamase producer was identified in 37.3% of E. coli and 50.4% of K. pneumoniae.

Conclusion

K. pneumoniae was the most frequent pathogen in culture-proven NS in South China, primarily associated with LOS in preterm, whereas GBS was the dominant pathogen in EOS. E. coli was common in both episodes with the highest mortality.

Clinical and Molecular Epidemiology of Invasive Group B Streptococcus Disease among Infants, China

Invasive group B Streptococcus (GBS) remains a leading cause of illness and death among infants globally. We conducted prospective and retrospective laboratory-based surveillance of GBS-positive cultures from infants <3 months of age in 18 hospitals across China during January 1, 2015-December 31, 2017. The overall incidence of GBS was 0.31 (95% CI 0.27-0.36) cases/1,000 live births; incidence was 0-0.76 cases/1,000 live births across participating hospitals. The case-fatality rate was 2.3%. We estimated 13,604 cases of GBS and 1,142 GBS-associated deaths in infants <90 days of age annually in China. GBS isolates were most commonly serotype III (61.5%) and clonal complex 17 (40.6%). Enhanced active surveillance and implementation of preventive strategies, such as maternal GBS vaccination, warrants further investigation in China to help prevent these infections.

Inhibition of SIRT1 by microRNA-9, the key point in process of LPS-induced severe inflammation

Severe inflammation may lead to multiple organs dysfunction syndrome, which has a high mortality. MicroRNA is found participated in this process. In this study we developed a lipopolysaccharide-induced inflammation cell model on macrophages and a lipopolysaccharide-induced inflammation mouse model. It was found that during inflammation, microRNA-9 was increased, accompanied with the up-regulation of pro-inflammatory cytokines and anti-inflammatory cytokines. Down-regulation of microRNA-9 inhibited the up-regulation of inflammatory cytokines, promoted the up-regulation of anti-inflammatory cytokines and induced the remission of organ damage, showing a protective effect in inflammation. Bioinformatics analysis combined with luciferase reporter assay showed that SIRT1 was the target gene of microRNA-9. Transfection of microRNA-9 inhibitor could increase the level of SIRT1 and decrease the activation of NF-κB pathway in macrophages. Myeloid specific sirt1 knockout mice were included and we found that lack of SIRT1 in mice macrophages led to aggravated inflammation, cell apoptosis and organ injury, and eliminated the protective property of microRNA-9 inhibitor. In conclusion, we demonstrated that inhibition of microRNA-9 could alleviate inflammation through the up-regulation of SIRT1 and then suppressed the activation of NF-κB pathway. This is a meaningful explore about the specific mechanism of microRNA-9 in inflammation.

Outcome of a screening program for the prevention of neonatal early-onset group B Streptococcus infection: a population-based cohort study in Inner Mongolia, China

PURPOSE

Invasive early-onset group B Streptococcus infection (EOGBS) is an important cause of severe neonatal complications but study on comprehensive GBS screening is lacking in China. This study aims to investigate the outcome of a regional anterpartum screening program for EOGBS prevention and to estimate the pros and cons of a new GBS screening strategy employed.

METHODS

We performed an optimized hospital strategy for GBS screening, which targeted expectant mothers (including those with preterm births) from January 2016 to December 2016 in a population-based cohort. Three common screening strategies were simulated to estimate the availability of the hospital strategy used in this study.

RESULTS

Altogether, 9770 eligible women were tested and the rate of GBS carriage was 2.7  % (266/9770). In total, 198 of the 266 maternal GBS carriers accepted intrapartum antibiotic prophylaxis (IAP) treatment. Among the 9860 neonates of 9770 mothers, four cases of EOGBS infection were identified and one case was missed (EOGBS incidence with screening and IAP: 0.5/1000). Risk factors for maternal GBS colonization included preterm birth (between 35 and 37 weeks) [odds ratio (OR)=1.7 (95  % confidence interval: 1.22-2.33)], region of origin, resident areas, maternal age (older than 34 years) [OR=1.5 (1.06-2.09)], prelabour rupture of membranes [OR=1.8 (1.34-2.35)], gestational diabetes mellitus [OR=1.6 (1.14-2.28)] and maternal mild anemia (Hb: 90-110 g dl^-1) [OR=1.5 (1.16-2.06)]. This new screening strategy resulted in less antibiotic exposure and least number of cases missed.

CONCLUSIONS

Our findings illustrate that this perinatal screening (including preterm births) for prevention of EOGBS infection can be implemented in the Inner Mongolian area.

An increasing trend of neonatal invasive multidrug-resistant group B streptococcus infections in southern China, 2011-2017

Background

A multidrug-resistant (MDR) RR2 gene cluster was identified by whole-genome sequencing in several highly virulent (ST-17) Group B streptococcus (GBS) isolates, which caused neonatal invasive infections in southern China in 2016. Tracing the transmission and distribution of MDR isolates in this area is important for the effective management of future infections. The aim of this study was to obtain longitudinal data of MDR isolates to monitor epidemiological trends of general common isolates in southern China, and provide evidence for future characterization of antimicrobial resistance mechanisms.

Methods

Clinical information and antimicrobial susceptibility of GBS isolates were acquired from electronic information management system databases of the hospital under study between January 2011 and December 2017. To confirm the presence of intact RR2, the tetO, ant6, lnuB, and ant9 genes located upstream, midstream, and downstream of RR2 were detected by PCR and DNA sequencing.

Results

A total of 149 cases of neonatal invasive GBS infection were identified during the period 2011–2017. Among them, 119 cases (79.9%) were caused by MDR isolates, with a general increasing trend over the past 7 years. Further characterization of 11 isolates showed that six isolates causing late-onset disease (LOD) carry the tetO, ant6, and lnuB genes, which are located on RR2. Moreover, lnuB and ant9 consistently co-occurred in GBS isolates, which suggests their close proximity to one another in the RR2 gene cluster.

Conclusion

The MDR GBS is responsible for a large number of neonatal invasive infections and occurs with increasing frequency over time. Particularly, the MDR GBS isolates that cause LOD are more likely to carry the RR2 gene cluster, compared with those that cause early-onset disease. The rise in number of MDR GBS isolates emphasizes the pressing need for continuous surveillance to monitor their antibiotic susceptibility and epidemiology.

Colonization prevalence and antibiotic susceptibility of Group B Streptococcus in pregnant women over a 6-year period in Dongguan, China

This study investigated the prevalence of recto-vaginal Group B Streptococcus (GBS) colonization, serotype distribution, and antimicrobial susceptibility patterns among pregnant women in Dongguan, China. Recto-vaginal swabs were collected from pregnant women at gestational age 35–37 weeks between January 1^st 2009 and December 31^st 2014. Isolates were serotyped by latex-agglutination and were tested against seven antimicrobials by disk diffusion. Of 7,726 pregnant women who completed GBS testing, 636 (8.2%) were GBS carriers. Of 153 GBS isolates available for typing, 6 serotypes (Ia, Ib, III, V, VI and VIII) were identified with type III being predominant, while 9 (5.9%) were non-typable isolates. All isolates were sensitive to penicillin, ceftriaxone, linezolid and vancomycin, whereas 52.4% were resistant to clindamycin, 25.9% were resistant to levofloxacin and 64.9% were resistant to erythromycin. This study showed the recto-vaginal colonization prevalence of GBS in Dongguan is significant. Due to 100% susceptibility to penicillin of all GBS samples, penicillin remains the first recommendation for treatment and prevention against GBS infection. Susceptibility testing should be performed for women allergic to penicillin in order to choose the most appropriate antibacterial agents for treatment and prevention of vertical transmission to neonates. In addition, we suggest establishing standard processes for GBS culture and identification in China as early as possible.