Staphylococcus aureusClinical Isolates: Antibiotic Susceptibility, Molecular Characteristics, and Ability to Form Biofilm

Abstract

Periodic monitoring of Staphylococcus aureus characteristics in a locality is imperative as their drug-resistant variants cause treatment problem. In this study, antibiograms, prevalence of toxin genes (sea-see, seg-ser, seu, tsst-1, eta, etb, and etd), PFGE types, accessory gene regulator (agr) groups, and ability to form biofilm of 92 S. aureus Thailand clinical isolates were investigated. They were classified into 10 drug groups: groups 1–7 (56 isolates) were methicillin resistant (MRSA) and 8–10 (36 isolates) were methicillin sensitive (MSSA). One isolate did not have any toxin gene, 4 isolates carried one toxin gene (seq), and 87 isolates had two or more toxin genes. No isolate had see, etb, or tsst-1; six isolates had eta or etd. Combined seg-sei-sem-sen-seo of the highly prevalent egc locus was 26.1%. The seb, sec, sel, seu, and eta associated significantly with MSSA; sek was more in MRSA. The sek-seq association was 52.17% while combined sed-sej was not found. Twenty-three PFGE types were revealed, no association of toxin genes with PFGE types. All four agr groups were present; agr group 1 was predominant (58.70%) but agr group 2 strains carried more toxin genes and were more frequent toxin producers. Biofilm formation was found in 72.83% of the isolates but there was no association with antibiograms. This study provides insight information on molecular and phenotypic markers of Thailand S. aureus clinical isolates which should be useful for future active surveillance that aimed to control a spread of existing antimicrobial resistant bacteria and early recognition of a newly emerged variant.

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

“…(Kwon et al, 2008). Other studies showed no difference in biofilm formation between MRSA and MSSA isolates (Smith et al, 2008;Indrawattana et al, 2013). In our study there was also no difference in biofilm formation between MRSA and MSSA isolates, although the mean optical density for MSSA was higher.…”

Detection and Measurement of Staphylococcal Enterotoxin-Like K (SEl-K) Secretion by Staphylococcus aureus Clinical Isolates

“…One of these toxins, SEl-K, has been shown to exhibit superantigenic properties, including V␤-specific T cell activation, pyrogenicity, emesis, and lethality in primates (7)(8)(9). Epidemiological studies have demonstrated the SEl-K-encoding genes to be among the most common SE genes in S. aureus clinical isolates (10)(11)(12)(13)(14). Additionally, SEl-K is the only SE gene to our knowledge that is significantly associated with community-acquired methicillin-resistant S. aureus (CA-MRSA) strains of several clonal lineages (10,15,16).…”

Accessory Gene Regulator Types of Staphylococcus aureus Isolated in Gorgan, North of Iran

“…In the study done by van Leeuwen and colleagues' [13] on a collection of 192 S. aureus strains, 71% of strains were found to belong to agr Group I and in the study done by Najar Peerayeh and colleagues [15] on a collection of 212 S. aureus strains, 55.1% of strains were found to belong to agr Group I. In a more recent study done by Indrawattana and colleagues in 2013 in Thailand, it was found that agr specific Group I (58.7%) was predominant agr Group [16].…”