In vitro characterization of representative clinical South African Staphylococcus aureus isolates from various clonal lineages

Oosthuysen, Wilhelm F.; Orth, Heidi; Lombard, Carl; Sinha, Bhanu; Wasserman, E

doi:10.1002/nmi2.53

Cited by 6 publications

(6 citation statements)

References 37 publications

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“…Only three of the studied strains did not show the fnba gene [15, 24 and 72]. This is a high percentage (96.3%) of fnba-encoding genes but is in agreement with previous studies conducted in other African countries [52,53]. The high prevalence of α-haemolysin and fibronectin binding protein A is not unusual and could explain the high virulence of these infections, as they play a crucial role in colonisation and infection [16,24].…”

Section: Plos Onesupporting

confidence: 85%

Study of susceptibility to antibiotics and molecular characterization of high virulence Staphylococcus aureus strains isolated from a rural hospital in Ethiopia

et al. 2020

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We characterised 80 Staphylococcus aureus strains isolated from human patients with SSTIs at a rural hospital in Ethiopia. Susceptibility to antibiotic of all strains was tested. The MLST method was used to type and a phylogenetic analysis was conducted employing the sequences of 7 housekeeping genes. PCR amplification was used to investigate the presence of the following virulence genes in all strains: hla (α-haemolysin), tstH (toxic shock syndrome toxin), luk PV (Panton-Valentine leukocidin), fnbA (fibronectin binding protein A) and mecA (methicillin resistance). Most of the strains were resistant to penicillin and ampicillin, but only 3 strains were resistant to oxacillin, and 1 of them was a true MRSA. The MLST results showed a high diversity of sequence types (ST), 55% of which were new, and ST152 was the most prevalent. A phylogeny study showed that many of the new STs were phylogenetically related to other previously described STs, but bore little relationship to the only ST from Ethiopia described in the database. Virulence gene detection showed a high prevalence of strains encoding the hla, fnbA and pvl genes (98.77%, 96.3% and 72.84%, respectively), a low prevalence of the tst gene (13.58%) and a markedly low prevalence of MRSA (1.25%). S. aureus strains isolated from patients in a rural area in Ethiopia showed low levels of antibiotic resistance, except to penicillin. Moreover, this study reveals new STs in Eastern Africa that are phylogenetically related to other previously described STs, and confirm the high prevalence of the pvl gene and the low prevalence of MRSA on the continent.

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Section: Plos Onesupporting

confidence: 85%

Study of susceptibility to antibiotics and molecular characterization of high virulence Staphylococcus aureus strains isolated from a rural hospital in Ethiopia

et al. 2020

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“…Certain pandemic MRSA clones are spread worldwide. Recent publications describe the ST612-MRSA-IV clone (MLST CC8) as the most widespread MRSA clone in Cape Town, and South Africa (Jansen van Rensburg et al, 2011;Orth et al, 2013;Oosthuysen et al, 2013;Moodley et al, 2010). In this study ST 612 formed strong biofilms, which may contribute to its dominance in nosocomial infections in South Africa.…”

Section: Discussionmentioning

confidence: 69%

“…Pulsed-field gel electrophoresis (PFGE) is considered the reference standard for S. aureus strain typing and is the most discriminatory typing method (Deurenberg et al, 2007;Oosthuysen et al, 2013). The method described by McDougal et al was followed (McDougal et al, 2003).…”

Section: Methodsmentioning

confidence: 99%

Biofilm formation in invasive Staphylococcus aureus isolates is associated with the clonal lineage

Naicker

Karayem

Hoek

et al. 2016

Microbial Pathogenesis

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2 Declaration I, Preneshni Rochelle Naicker, hereby declare that the work contained in this assignment is my original work and that I have not previously submitted it, in its entirety or in part, at any university for a degree. The ability to form biofilms contributes significantly to the virulence of Staphylococcus aureus. Virulence factors may be associated with certain S. aureus lineages. However, the contribution of the genetic background of S. aureus to biofilm formation is poorly understood. This study investigated the association between the genetic background and the biofilm forming ability of clinical invasive S. aureus isolates. Secondary objectives included investigating any correlation with biofilm formation and methicillin resistance or the source of bacteraemia. Methods:The study was conducted at a 1300-bed tertiary hospital in Cape Town, South Africa. S. aureus isolates obtained from blood cultures between January 2010 and January 2012 were included. Genotypic characterization was performed by PFGE, spa typing, SCCmec typing and MLST. Thirty genotypically unique strains were assessed for phenotypic biofilm formation with the microtitre plate assay. All isolates were tested in triplicate and an average optical density, measured at a wavelength of 490nm, was determined. The biofilm forming ability of isolates with A 490 > 0.17 was considered 'weak positive' and A 490 > 0.34 'strong positive'. Isolates with A 490 ≤ 0.17 were considered non-adherent. ANOVA with Bonferroni-adjusted post-hoc tests and t-tests were used for statistical analysis of the association between biofilm forming ability and strain characteristics.Results: Fifty seven percent of isolates were capable of forming biofilms. Weak biofilm formation occurred in 40% (n=12) and strong biofilm formation in 17% (n=5) of isolates. Thirteen (43%) of the isolates were classified as non-adherent. All 5 isolates capable of strong biofilm formation belong to one spa clonal complex (spa-CC 064). Strains from spa-CC 064 were capable of higher biofilm formation than other spa clonal complexes (p=0.00002). These 5 strains belonged to MLST CC5 and CC8. Biofilm formation did not correlate with methicillin resistance and was not related to the source of bacteraemia. Conclusion:Biofilm formation correlates with the spa clonal lineage in our population of invasive S. aureus strains. High biofilm formation was associated with spa-CC 064. MLST CC5 and CC8 strains are capable of strong biofilm formation.

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“…Previous studies have reported the prevalence and diversity of clinical MRSA isolate in Pretoria, South Africa [ 4 , 5 ]. However, there are no reports on the distribution patterns of the multidrug efflux genes of the clinical isolates in South Africa.…”

Section: Introductionmentioning

confidence: 99%

Diversity of Multidrug Efflux Genes and Phenotypic Evaluation of the In vitro Resistance Dynamics of Clinical Staphylococcus Aureus Isolates Using Methicillin; a Model β-lactam

Antiabong¹,

Kock²,

Mbelle³

et al. 2017

TOMICROJ

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Objectives:Methicillin-resistant Staphylococcus aureus (MRSA) across the world often leave clinicians with little or no choice of treatment options. The multi-drug efflux (MDE) genes are bacterial survival mechanisms responsible for the pumping out of antibiotics and other biocides from the cytoplasm. Whilst effort is being made in the development of antibiotic adjuvants such as efflux pumps inhibitors, information is needed on the diversity of these MDEs in the circulating S. aureus and on the growth dynamics of the clinical isolates in response to antibiotics is not regularly examined.Methods:Here, we evaluated the diversity of MDEs in cinical S. aureus recovered in a tertiary academic hospital, Pretoria, South African hospital using PCR and also employed visual minimum inhibitory concentration and quantitative analysis of spectrophometric measurements of bacterial growth in the presence of a model β lactam antibiotic (methicillin), to phenotypically elucidate the resistance pattern of these isolates in response to methicillin.Results:Three major distribution patterns of MDEs were observed in the clinical isolates evaluated. Moreover, norA, nor B and tet38 were present in 98.9% of the isolates while other MDE were present in different proportions ranging from 40 to 98.6% of the isolates. In addition, S. aureus isolates, be it of MRSA or MSSA genotype did not habour the same set of MDEs despite being recovered from the same hospital setting. Finally, we showed that MSSA displayed phenotypic resistance to methicilllin despite the non-detection of the mecA resistance gene.Conclusions:Our data suggest that the growth of S. aureus may be enhanced by β lactams (methicillin) and that MSSA may also display resistance to methicillin and perhaps other β lactam antibiotics. The high prevalence of MDEs suggestive of resistance to a broad spectrum of biocides and fluoroquinolones are particularly disturbing.

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In vitro characterization of representative clinical South African Staphylococcus aureus isolates from various clonal lineages

Cited by 6 publications

References 37 publications

Study of susceptibility to antibiotics and molecular characterization of high virulence Staphylococcus aureus strains isolated from a rural hospital in Ethiopia

Study of susceptibility to antibiotics and molecular characterization of high virulence Staphylococcus aureus strains isolated from a rural hospital in Ethiopia

Biofilm formation in invasive Staphylococcus aureus isolates is associated with the clonal lineage

Diversity of Multidrug Efflux Genes and Phenotypic Evaluation of the In vitro Resistance Dynamics of Clinical Staphylococcus Aureus Isolates Using Methicillin; a Model β-lactam

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