Relevance of biofilm formation and virulence of different species of coagulase-negative staphylococci to public health

Abstract

The ability of biofilm formation seems to play an essential role in the virulence of coagulase-negative staphylococci (CNS). The present work aimed to: (a) evaluate the biofilm-forming ability of different strains of CNS field isolates; (b) evaluate their virulence potential through the assessment of the Madin-Darby canine kidney (MDCK) cytotoxicity assay; (c) determine the frequency of biofilm-associated genes among these CNS isolates. Biofilm markers associated with biofilm formation and MDCK cells cytotoxicity were compared to find possible associations with pathogenicity. CNS isolates (n = 94) belonging to 11 different species were tested for slime production using the tube test (TA) and the Congo red agar plate test (CRA), while the presence of icaA and icaD genes were evaluated by d-PCR. Two points were addressed for the first time: (1) the specific relationship between slime phenotype and icaD gene expression; (2) the specific relationship between slime phenotype, icaAD genes, and MDCK cytotoxicity. The proportion of biofilm-positive/icaD-positive versus biofilm-positive/icaD-negative strains was 9:0 and 9:0 (81.8%) by the TA and CRA, which clearly indicates that icaD was a more reliable gene to be accounted for in the biofilm formation. MDCK recorded a higher proportion than that recorded by the CRA and TA results (MDCK-positive/icaD-positive versus MDCK-positive/icaD-negative 10:0, 90.9%). Evaluation of the ica operon, CRA plate test, TA, and MDCK can contribute to the high clinical impact in the management of antibiotic therapy, in infections associated with devices in veterinary medicine, the dairy industry, and food processing.

Detection of Biofilm Production Capability and icaA/D Genes Among Staphylococci Isolates from Shiraz, Iran

“…In the present investigation, the icaA and icaD were evaluated because the detection of these genes implies the biofilm formation by staphylococcal isolates. In addition, these genes regulate the slime production (7,13). In our study, the presence of icaA gene in all tested isolates was associated with the presence of icaD gene and vice versa, which has also been mentioned by other authors (28,34).…”

“…This discrepancy can be attributed to the presence of other molecules involved in the biofilm formation such as ClpP, BHP, and Aae among CoNS isolates (13). Moreover, different studies have demonstrated that the expression of the ica locus is considerably variable and can be affected by many factors, which, in turn, results in the increase or decrease of biofilm production (7). The elucidation of the adhesive processes among clinical isolates might be a solution for developing anti-adhesive approaches to fight with infections due to opportunistic bacteria.…”

“…However, staphylococcal infections are often caused by strains that have colonized in parts of the human body and make the colonized persons a reservoir for the spread of the organisms (4,5). Due to the biofilm producing ability of staphylococci, they are mostly associated with chronic and implanted medical devices infections (6,7). Staphylococcus epidermidis was the first species identified as biofilm producer; however, the same capacity was subsequently implicated in S. aureus and other coagulase negative Staphylococci (CoNS) (8,9).…”

Tetracycline resistance phenotypes and genotypes of coagulase-negative staphylococcal isolates from bubaline mastitis in Egypt

“…This was in agreement with that of Osman et al . [21], with an incidence of S. intermedius (31.8%) and S. xylosus (29.5%), respectively.…”

Characterization ofStaphylococcus epidermidisstrains isolated from industrial cleanrooms under regular routine disinfection

“…Osman et al . () stated that adherence to a surface and the crystal violet assay are the best phenotypic methods for sensitivity and specificity according to PCR detection of the ica genes. In the present study, different degrees of biofilm formation were obtained for different strains with different combinations of these biofilm genes.…”