Molecular Epidemiology of Staphylococcus epidermidis Implicated in Catheter-Related Bloodstream Infections at an Academic Hospital in Pretoria, South Africa

Abstract

Staphylococcus epidermidis is one of the most prevalent pathogens implicated in catheter-related bloodstream infections (CRBSI) at an academic hospital in Pretoria, South Africa. Little is known about the clonality and the prevalence of antibiotic resistance and virulence genes in S. epidermidis (e.g., icaAB, IS256, mecA, and qacA/B). A total of 508 intravascular catheters (IVCs) from 331 patients were submitted for culture from May to October 2013. Only 50% (n = 253/508) of the IVCs were accompanied by blood cultures (BCs) taken within 48 h. Forty-four percent (44%; n = 112/253) of IVCs were colonised, of which 26% (n = 65/253) were associated with a CRBSI. We identified S. epidermidis as the causal agent in 31% (n = 20/65) of the CRBSI cases. Fifty-nine S. epidermidis isolates were obtained, 23 isolates were cultured from 22 IVCs and 36 isolates were cultured from 36 BCs. All S. epidermidis isolates were resistant to β-lactams (100%; n = 59/59), followed by high levels of resistance toward erythromycin (86%; n = 51/59) and gentamicin (81%; n = 49/59). The mecA gene was prevalent in all the (100%, n = 59/59) isolates. Isolates contained the IS256 element (83%, n = 49/59), the icaAB gene (81%, n = 48/59) and, the qacA/B gene (81%, n = 48/59). All 48 isolates were qacA positive upon restriction enzyme digestion of the qacA/B amplicons. Phenotypic resistance toward 0.5% (m/v) chlorhexidine was not observed. Staphylococcal Cassette Chromosome (SCC) mec typing showed that SCCmec type IV (31%; n = 18/59) was the most prevalent. The remaining SCCmec elements were highly diverse. Pulsed-field gel electrophoresis (PFGE) showed that S. epidermidis isolates from individual patients were mostly clonal. Multilocus sequencing typing (MLST) of 10 sequenced isolates showed that sequence type (ST) 2 (40%; n = 4/10) was the most frequently detected, followed by ST54 (20%; n = 2/10), ST28 (10%; n = 1/10), ST59 (10%; n = 1/10) and ST490 (10%; 1/10). One isolate was newly assigned to ST596. These S. epidermidis infections can be attributed to patients' skin microflora or to poor infection control practices. Currently, S. epidermidis strains circulating in the studied hospital are multidrug-resistant and highly adaptive to environmental changes.

Review of Clinically and Epidemiologically Relevant Coagulase-Negative Staphylococci in Africa

“…The same study using MLST, grouped isolates mainly into the groups; sequence type (ST) 2 as the most predominant, followed by ST54, ST59, and ST490 in descending order of predominance, with one isolate being assigned to a new group, ST596. 75 SCCmec types I, II, IV, and V/VII have also been reported in a Tunisian study, which also found diverse PFGE patterns within mecA-positive CoNS isolates. The observation of similar SCCmec and PFGE patterns of MR-CoNS across different sources in that study means there was the transfer and circulation of the same clones at the human/animal/environment interface.…”

“…The study also showed that 81% of S. epidermidis isolates carried the qacA/B and icaAB genes each. 75…”

Genotypic and phenotypic analysis of biofilm formation Staphylococcus epidermidis isolates from clinical specimens

“…Regarding the number of isolates in Tehran, Similar results were observed in the previously published studies. The frequency of S. epidermidis in other studies in Belgium 2013 (33), Africa 2018 (20), and Netherland 2019 (27) were assessed respectively [5][6][7]. Biofilm formation capability could enhance the durability of the mentioned bacterium against disinfection principles in hospitals in the current study [16].…”

“…The recent findings in Iran were shown S. epidermidis isolated strains from various clinical specimens more ubiquitous prevalence in other Iranian cities (73.9%) than Tehran (56.65%) [4]. Other worldwide conducted researches also have shown high isolation rates of the mentioned bacterium in clinical specimens, especially in medical devices samples [5][6][7]. Biofilms are notoriously resistant to immune system responses and antimicrobial agents.…”

Actividad antibacteriana de diatomeas marinas aisladas de Acapulco, Guerrero, México

“…El hecho de que el extracto con diclorometano de C. curvisetus haya mostrado actividad antibacteriana frente a aislados clínicos, es de gran importancia ya que las infecciones causadas por bacterias productoras de BLEE y Staphylococcus RM son un problema mundial que incrementa la morbilidad y mortalidad de los pacientes hospitalizados y en pacientes en la comunidad. E. coli predominantemente como un agente patógeno de infecciones del tracto urinario (Navarro-Navarro et al 2011, Morones-Esquivel et al 2016, S. epidermidis en infecciones nosocomiales (Castro-Alarcón et al 2011, Ehlers et al 2018 y Klebsiella pneumoniae productoras de carbapenemasas es un importante patógeno relacionado a brotes en centros médicos (Ramos-Castañeda et al 2018), por lo que se hace necesario identificar nuevos compuestos que permitan disminuir esta problemática.…”