Analysis of virulence factors and antibiotic resistance genes in group B streptococcus from clinical samples

Abstract

Background Streptococcus agalacticae (Group B Streptococcus, GBS) is one of the most important causative agents of serious infections among neonates. This study was carried out to identify antibiotic resistance and virulence genes associated with GBS isolated from pregnant women. Methods A total of 43 GBS isolates were obtained from 420 vaginal samples collected from HIV positive and negative women who were 13–35 weeks pregnant attending Antenatal Care at Chitungwiza and Harare Central Hospitals in Zimbabwe. Identification tests of GBS isolates was done using standard bacteriological methods and molecular identification testing. Antibiotic susceptibility testing was done using the modified Kirby-Bauer method and E-test strips. The boiling method was used to extract DNA and Polymerase Chain Reaction (PCR) was used to screen for 13 genes. Data was fed into SPSS 24.0. Results Nine distinct virulence gene profiles were identified and hly-scpB-bca-rib 37.2% (16/43) was common. The virulence genes identified were namely hly 97.8% (42/43), scpB 90.1% (39/43), bca 86.0% (37/43), rib 69.8% (30/43) and bac 11.6% (5/43). High resistance to tetracycline 97.7% (42/43) was reported followed by 72.1% (31/43) cefazolin, 69.8% (30/43) penicillin G, 58.1% (25/43) ampicillin, 55.8% (24/43) clindamycin, 46.5% (20/43) ceftriaxone, 34.9% (15/43) chloramphenicol, and 30.2% (13/43) for both erythromycin and vancomycin using disk diffusion. Antibiotic resistance genes among the resistant and intermediate-resistant isolates showed high frequencies for tetM 97.6% (41/42) and low frequencies for ermB 34.5% (10/29), ermTR 10.3% (3/29), mefA 3.4% (1/29), tetO 2.4% (1/42) and linB 0% (0/35). The atr housekeeping gene yielded 100% (43/43) positive results, whilst the mobile genetic element IS1548 yielded 9.3% (4/43). Conclusion The study showed high prevalence of hly, scpB, bca and rib virulence genes in S. agalactiae strains isolated from pregnant women. Tetracycline resistance was predominantly caused by the tetM gene, whilst macrolide resistance was predominantly due to the presence of erm methylase, with the ermB gene being more prevalent. Multi-drug resistance coupled with the recovery of resistant isolates to antimicrobial agents such as penicillins indicates the importance of GBS surveillance and susceptibility tests. It was also observed that in vitro phenotypic resistance is not always accurately predicted by resistance genotypes.

Prevalence, Resistance Profile and Virulence Genes of Streptococcus agalactiae Colonizing Near-term Pregnant Women Attending Ain Shams University Hospital

“…On the other hand, the presence of rib gene was confirmed only in 18 isolates (78.26%). This result concides with Sadaka et al 18 and Mudzana et al 65 who detected the presence of rib gene in 79.2% and 69.8% of isolates respectively, while Hannoun et al 10 and Lysakowska et al 11 detected this gene in only 35% and 33% of isolates respectively.…”

“…This result agrees with Sadaka et al 18 , Dmitriev et al 69 , Dutra et al 70 and Bobadilla 71 who also detected the presence of scpB gene in all isolates. However, other studies by Hannoun et al 10 , Mudzana et al 65 and Lysakowska et al 11 detected scpB in 94.7%, 90.1% and 92.5% of human isolates respectively.…”

“…On the other hand ceftriaxone and cefotaxime non-susceptible GBS isolates were found in studies by Simoes et al 63 , Kitamura et al 64 and Mudzana et al 65 .…”

The Role of Streptococcus spp. in Bovine Mastitis

“…The hly gene found in S. agalactiae is a virulence factor that codes for hyaluronate lyase. The protein is capable of cleaving hyaluronan, allowing for an easier invasion and spread of GBS, similar to the action of streptokinase in S. dysgalactiae [ 55 , 56 ]. pauA is notable since it was the first described plasminogen activator affecting bovine plasminogen.…”

Emergence of Multi-Drug Resistance and Its Association With Uncommon Serotypes of Streptococcus agalactiae Isolated From Non-neonatal Patients in Thailand

“…In addition to the capsular polysaccharide, there are other important factors involved in GBS pathogenesis that influence virulence, such as cell surface antigens, Rib, and alpha antigen of C protein encoded by the rib and bca genes ( Smith et al, 2007 ; Mudzana et al, 2021 ). Fibrinogen- and laminin-binding protein for human cell adherence are regulated by pavA and lmb , respectively ( Smith et al, 2007 ; Tenenbaum et al, 2007 ).…”