Production of icaADBC-encoded polysaccharide intercellular adhesin and therapeutic failure in pediatric patients with staphylococcal device-related infections

Abstract

BackgroundBiofilm production has been established as a virulence factor which allows Staphylococcus to adhere and persist in medical devices. The objective was to determine whether therapeutic failure in patients infected with Staphylococcus spp. is linked to biofilm production, the presence of the ica operon, and the bacterial insertion sequence element IS256.MethodsStaphylococcus spp. isolates from patients with device-related infections were collected. Therapeutic failure with proper antimicrobial treatment was registered. Biofilm phenotype was determined by Congo red test agar and Christensen assay. Presence of the ica operon genes A-D and IS256 was detected by PCR. Differences were compared through x2.Results100 isolates from staphylococcal infections episodes were included: 40 sepsis/bacteremia, 32 ependymitis, and 28 peritonitis. 73.77% of CoNS and 79.5% of S. aureus isolates harbored the icaD gene, 29% of all isolates IS256-A+ IS256-D genes, icaA and icaB genes were only found in CoNS (27.8% and 21.3% respectively). Therapeutic failure occurred in 95.4.% of patients with a positive IS256-A+ IS256-D S. epidermidis isolate, RR 5.49 (CI 95% 2.24-13.44 p ≤ 0.0001), and 85.76% in CoNS isolates, RR 2.57 (CI 95% 0.97-6.80, p = 0.05). Although none S. aureus was positive for IS256-A + IS256-D, therapeutic failure was observed in 35.8%.ConclusionsThe presence of icaA/D genes along with the sequence element IS256 was associated with therapeutic failure in most CoNS infections, even though its absence in S. aureus isolates does not ensure therapeutic success.

Genetic determinants and biofilm formation of clinicalStaphylococcus epidermidisisolates from blood cultures and indwelling devises

“…Sixty-two percent of our isolates were icaA/D-positive, much more than what was determined in a study by Diemond-Hernández et al [30] for S. epidermidis. Approximately 32% of our isolates were able to produce biofi lm phenotypically.…”

Biofilm formation and antimicrobial resistance in methicillin-resistant Staphylococcus aureus isolated from burn patients, Iran

“…Challenges in the treatment of staphylococcal infections are accompanied by several mechanisms of biofilm formation in this bacterium [11]. There are several methods for the quantification of biofilm formation [29], but there is still no standard protocol for the detection of biofilm production.…”

“…The genes were amplified on an Eppendorf (Hamburg, Germany) thermocycler with a final volume of 20 μl containing 10 μl of Qiagen HotStarTaq master mix (Invitrogen, Carlsbad, USA, containing PCR buffer with 3 mM MgCl2, 400 µM of each dNTP and 2.5 units HotStarTaq DNA polymerase), 1 μl of each primer (20 pMol, MecA, ICAA and ICAD) (Table1) [11,18], 6 μL of RNasefree water, and 2 μl of DNA template. The products were then electrophoresed on agarose gel and the presence or absence of any resulting bands was evaluated.…”

“…Since the ability of biofilm production by MRSA increases antibiotic resistance, hospital patients infected with these strains are at serious risk for treatment failure [10]. Biofilm formation is considered to be a virulence factor because the microorganisms that establish in a burn wound biofilm fundamentally differ from suspended populations [11]. Biofilm acts as a barrier to antimicrobial agents and the host immune system that assists sustained bacterial colonization [12].…”

The Comparison ofStaphylococcus aureusIsolated From Blood and Wound Specimens for Genes Encoding Polysaccharide Intercellular Adhesion (PIA)

“…Biofilm formation allows the bacteria to resist higher concentrations of antimicrobial agents, environmental conditions and the host immune responses (3). The self-produced polymeric matrices (PIA) attach to inert and living surfaces (4). Penetration of antibiotics becomes impaired through S. aureus and S. epidermidis biofilms (5), although carbon and amino acids can be adsorbed by the biofilm layers (6).…”