Genomic characterisation of perinatal Western Australian Streptococcus agalactiae isolates

Macrolide and lincosamide resistance of Streptococcus agalactiae in pregnant women in Poland

Knowing about the antibiotic resistance, serotypes, and virulence-associated genes of Group B Streptococcus for epidemiological and vaccine development is very important. We have determined antimicrobial susceptibility patterns, serotype, and virulence profiles. The antibiotic susceptibility was assessed for a total of 421 Streptococcus agalactiae strains, isolated from pregnant women and neonates. Then, 89 erythromycin and/or clindamycin-resistant strains (82 isolates obtained from pregnant women and seven isolates derived from neonates) were assessed in detail. PCR techniques were used to identify the studied strains, perform serotyping, and assess genes encoding selected virulence factors. Phenotypic and genotypic methods determined the mechanisms of resistance. All tested strains were sensitive to penicillin and levofloxacin. The constitutive MLSB mechanism (78.2%), inducible MLSB mechanism (14.9%), and M phenotype (6.9%) were identified in the macrolide-resistant strains. It was found that macrolide resistance is strongly associated with the presence of the ermB gene and serotype V. FbsA, fbsB, fbsC, scpB, and lmb formed the most recurring pattern of genes among the nine surface proteins whose genes were analysed. A minority (7.9%) of the GBS isolates exhibited resistance to lincosamides and macrolides, or either, including those that comprised the hypervirulent clone ST-17. The representative antibiotic resistance pattern consisted of erythromycin, clindamycin, and tetracycline resistance (71.9%). An increase in the fraction of strains resistant to macrolides and lincosamides indicates the need for monitoring both the susceptibility of these strains and the presence of the ST-17 clone.

Molecular Epidemiology of Group B Streptococcus Colonization in Egyptian Women

(1) Background: Streptococcus agalactiae or Group B Streptococcus (GBS) causes severe neonatal infections with a high burden of disease, especially in Africa. Maternal vaginal colonization and perinatal transmissions represent the common mode of acquiring the infection. Development of an effective maternal vaccine against GBS relies on molecular surveillance of the maternal GBS population to better understand the global distribution of GBS clones and serotypes. (2) Methods: Here, we present genomic data from a collection of colonizing GBS strains from Ismailia, Egypt that were sequenced and characterized within the global JUNO project. (3) Results: A large proportion of serotype VI, ST14 strains was discovered, a serotype which is rarely found in strain collections from the US and Europe and typically not included in the current vaccine formulations. (4) Conclusions: The molecular epidemiology of these strains clearly points to the African origin with the detection of several sequence types (STs) that have only been observed in Africa. Our data underline the importance of continuous molecular surveillance of the GBS population for future vaccine implementations.

Molecular typing and prevalence of antibiotic resistance and virulence genes in Streptococcus agalactiae isolated from Chinese dairy cows with clinical mastitis

Bovine mastitis is a common disease occurring in dairy farms and can be caused by more than 150 species of pathogenic bacteria. One of the most common causative organisms is Streptococcus agalactiae, which is also potentially harmful to humans and aquatic animals. At present, research on S. agalactiae in China is mostly concentrated in the northern region, with limited research in the southeastern and southwestern regions. In this study, a total of 313 clinical mastitis samples from large-scale dairy farms in five regions of Sichuan were collected for isolation of S. agalactiae. The epidemiological distribution of S. agalactiae was inferred by serotyping isolates with multiplex polymerase chain reaction. Susceptibility testing and drug resistance genes were detected to guide the clinical use of antibiotics. Virulence genes were also detected to deduce the pathogenicity of S. agalactiae in Sichuan Province. One hundred and five strains of S. agalactiae (33.6%) were isolated according to phenotypic features, biochemical characteristics, and 16S rRNA sequencing. Serotype multiplex polymerase chain reaction analysis showed that all isolates were of type Ia. The isolates were up to 100% sensitive to aminoglycosides (kanamycin, gentamicin, neomycin, and tobramycin), and the resistance rate to β-lactams (penicillin, amoxicillin, ceftazidime, and piperacillin) was up to 98.1%. The TEM gene (β-lactam-resistant) was detected in all isolates, which was in accordance with a drug-resistant phenotype. Analysis of virulence genes showed that all isolates harbored the cfb, cylE, fbsA, fbsB, hylB, and α-enolase genes and none harbored bac or lmb. These data could aid in the prevention and control of mastitis and improve our understanding of epidemiological trends in dairy cows infected with S. agalactiae in Sichuan Province.

Molecular determination, serotyping, antibiotic profile and virulence factors of group B Streptococcus isolated from invasive patients at Arabcare Hospital Laboratory, Palestine

BACKGROUND

Streptococcus agalactiae (group B Streptococcus) is beta-hemolytic, catalase negative, gram-positive cocci, recognized as main bacterial pathogen causing infections in newborns, infants, adults, and elderly people around the world. The aim of this study is to investigate group B Streptococcus samples recovered from invasive patients and determine serotype, virulent genes, and antibiotic-resistant profile of Streptococcus agalactiae in Palestine.

METHODS

A total of 95 group B Streptococcus strains were isolated from neonates, infants, pregnant and non-pregnant women and males at Arabcare Hospital Laboratory, Palestine, between the period of June 2018 and September 2020. Species identification was carried out through cultivation and conventional biochemical tests. A conventional Polymerase Chain Reaction (cPCR) was used to determine the 5 serotypes and virulent genes of the Streptococcus agalactiae strains. The antibiotic resistance test of group B Streptococcus was evaluated using Kirby-Bauer disk susceptibility. Sequencing and BLAST analysis were used to determine the relationship of the isolates in this study to worldwide isolates.

RESULTS

Serotype III (35%) was the major group B Streptococcus strains serotype causing invasive infections in neonates, infants, pregnant and nonpregnant women, and males, followed by serotypes V (19%), Ia, and II (15%), Ib (6%), respectively. All our isolates encoding for surface protein virulent factors, including a highly virulent gene (HvgA) were mostly found in strains isolated from pregnant women (12%). These group B Streptococcus strains exhibited a high rate of resistance to clindamycin (26%). The overall percentage of levofloxacin resistance was 11%, while vancomycin and ampicillin showed higher resistance, at 14.7 and 16% respectively. In addition, the phylogenetic relationship dendrogram illustrates that Streptococcus agalactiae isolated from an invasive patient (newborn) in Palestine was similar to strains found in China and Japan.

CONCLUSIONS

The outcomes of this study demonstrate that resistant group B Streptococcus strains are common in Palestine, therefore, evidence-based infection prevention and antibiotic stewardship efforts are necessary.

Genomic epidemiology of group B streptococci spanning 10 years in an Irish maternity hospital, 2008-2017

OBJECTIVES

The genomic epidemiology of group b streptococcal (GBS) isolates from the Rotunda maternity hospital, Dublin, 2008-2017, was investigated.

METHODS

Whole genome sequences of isolates (invasive, n = 114; non-invasive, n = 76) from infants and women were analysed using the PubMLST database (https://pubmlst.org/sagalactiae/).

RESULTS

Serotypes III (36%), Ia (18%), V (17%), II (11%) and Ib, (9%) and sequence types (ST) 17 (23%), ST-23 (14%), ST-1 (12%) and ST-19 (7%) were most common. Core genome MLST (cgMLST) differentiated isolates of the same ST, grouped STs into five lineages congruent with known clonal complexes and identified known mother-baby pairs and suspected linked infant cases. Clonal complex (CC) 17 accounted for 40% and 22% of infant and maternal invasive cases, respectively and 21% of non-invasive isolates. CC23 and CC19 were associated with maternal disease (30%) and carriage (24%), respectively. Erythromycin (26%) and clindamycin (18%) resistance increased over the study period and was associated with presence of the erm(B) gene (55%), CC1 (33%) and CC19 (24%). A multi-resistant integrative conjugative element incorporated in the PI-1 locus was detected in CC17, an ST-12 and ST-23 isolate confirming the global dissemination of this element. All isolates possessed one or more pilus islands. Genes encoding other potential protective proteins including Sip, C5a peptidase and Srr1 were present in 100%, 99.5% and 65.8% of isolates, respectively. The srr2 gene was unique to CC17.

CONCLUSIONS

The PubMLST.org website provides a valuable framework for genomic GBS surveillance to inform on local and global GBS epidemiology, preventive and control measures.

Whole genome sequencing for antimicrobial resistance mechanisms, virulence factors and clonality in invasive Streptococcus agalactiae blood culture isolates recovered in Australia

Invasive Streptococcus agalactiae (Group B streptococci, GBS) infections result in a large burden of disease globally. Changes in clinical and molecular epidemiology, as well as antibiotic resistance patterns, are being described globally amongst GBS isolates. Very little is known about the characteristics of invasive GBS disease in the Australian setting. Therefore, this study aimed to define the clinical and genomic characteristics of invasive GBS isolates from the Sunshine Coast region in Australia. Thirty-two isolates were identified over a 3-year period. Known risk factors for disease were present in 71.9% and the leading site of disease was the skin and soft tissue (40.6%). Sequence types (ST) 1, 17 and 23 made up 50% with ST17 making up 56.2% of the total. Serotype Ia was the most prevalent (9/32, 28.1%). Clindamycin and erythromycin resistance was seen in 12.5% and 25%, respectively. Active surveillance and local knowledge of GBS epidemiology and antibiotic resistance has both patient and public health importance. Vaccine candidates are currently in their clinical phase of development.

Host range, morphological and genomic characterisation of bacteriophages with activity against clinical Streptococcus agalactiae isolates

Streptococcus agalactiae or Group B Streptococcus (GBS) is a leading cause of sepsis in neonates. As a preventative measure prophylactic antibiotic administration is common in pregnant women colonised with GBS, but antibiotic-resistance and adverse effects on neonatal microbiomes may result. Use of bacteriophages (phages) is one option for targeted therapy. To this end, four phages (LF1 –LF4) were isolated from wastewater. They displayed lytic activity in vitro against S. agalactiae isolates collected from pregnant women and neonates, with 190/246 isolates (77.2%) and 10/10 (100%) isolates susceptible to at least one phage, respectively. Phage genomes ranged from 32,205–44,768 bp and all phages were members of the Siphoviridae family. High nucleotide identity (99.9%) was observed between LF1 and LF4, which were closely related to a putative prophage of S. agalactiae. The genome organisation of LF2 differed, and it showed similarity to a different S. agalactiae prophage, while LF3 was more closely related to a Streptococcus pyogenes phage. Lysogenic gene presence (integrase, repressor and regulatory modules), was suggestive of temperate phages. In a therapeutic context, temperate phages are not ideal candidates, however, the broad host range activity of these phages observed on clinical isolates in vitro is promising for future therapeutic approaches including bioengineered phage or lysin applications.