ABSTRACT
Staphylococcus epidermidis is a commensal bacteria which inhabits on the surface of human skin and mucous membrane.It has been demonstrated that staphylococcus epidermidis is a major opportunistic pathogen that can cause clinical biomaterial related infection and plays an important role in biomaterial implantation associated infections.The main pathogenic factor is the formation of the bacterial biofilm on surface of medical biomaterial.The formation of bacterial biofilm can resist the defense reaction and antibiotic treatment effectively so that leading to the biomaterial implantation associated infection which is difficult to cure thoroughly,and make the infections become chronic,persistent and repetitive.Nowadays,the infections caused by Staphylococcus epidermidis have caused high clinical mortality.Staphylococcus epidermidis biofilm formation,the regulations of intercellular adhesion gene (ica) operon and accessory gene regulator (agr) gene on the formation of biofilm and their functions in clinical biomaterial related infections are reviewed in this article.
ABSTRACT
Objective To investigate the formation of biofilm in clinical isolates of Staphylococcus epidermidis ,and to analyse the correlation between biofilm formation and antibacterial resistance of Staphylococcus epidermidis .Methods A total of 62 strains of Staphylococcus epidermidis isolated from blood specimens of inpatients with bloodstream infection ,from January 2014 to February 2015 ,were collected .The biofilm formation of Staphylococcus epidermidis was detected by using the semi‐quantitative adherence as‐say and polymerase chain reaction(PCR) amplification experiment .The antibacterial susceptibility test was carried out according to K‐B method .Results The positive rate of biofilm formation detected by using the semi‐quantitative adherence assay and PCR for icaA gene were 37 .1% (23 strains) and 43 .5% (27 strains) respectively ,and there was no statistically significant difference(P>0 .05) .There were 14 positive strains detected by both methods .The resistance rates of strains producing biofilm to antibacterial a‐gents were generally higher than those of non‐producing biofilm strains ,and there were statistically significant differences in resist‐ance rates of strains to gentamicin ,penicillin ,oxacillin ,levofloxacin and cefoxitin(P<0 .05) .All bacteria were sensitive to vancomy‐cin ,linezolid and quinupristin/dalfopristin .Conclusion There is no significant difference between the two methods in detecing bio‐film formation .The resistance rates of strains producing biofilm to antibacterial agents were generally higher than those of non‐pro‐ducing biofilm strains .
ABSTRACT
Background & objectives: All colonizing and invasive staphylococcal isolates may not produce biofilm but may turn biofilm producers in certain situations due to change in environmental factors. This study was done to test the hypothesis that non biofilm producing clinical staphylococci isolates turn biofilm producers in presence of sodium chloride (isotonic) and high concentration of glucose, irrespective of presence or absence of ica operon. Methods: Clinical isolates of 100 invasive, 50 colonizing and 50 commensal staphylococci were tested for biofilm production by microtiter plate method in different culture media (trypticase soy broth alone or supplemented with 0.9% NaCl/ 5 or 10% glucose). All isolates were tested for the presence of ica ADBC genes by PCR. Results: Biofilm production significantly increased in the presence of glucose and saline, most, when both glucose and saline were used together. All the ica positive staphylococcal isolates and some ica negative isolates turned biofilm producer in at least one of the tested culture conditions. Those remained biofilm negative in different culture conditions were all ica negative. Interpretation & conclusions: The present results showed that the use of glucose or NaCl or combination of both enhanced biofilm producing capacity of staphylococcal isolates irrespective of presence or absence of ica operon.
ABSTRACT
Purpose: Staphylococcus epidermidis is a major commensal bacteria. Various strains of S. epidermidis are capable of forming biofilms by attaching to several surfaces. Biofilm-forming ability of this organism is found to be associated with many hospital-acquired infections and can even impair wound healing. S. epidermidis strains producing polysaccharide-biofilms possess the intercellular adhesion (ica) operon while strains forming the protein adhesion-mediated biofilms possess the accumulation associated protein (aap) gene. We screened for biofilm-forming S. epidermidis in the skin of healthy individuals in Tamil Nadu in order to determine the risk of acquiring S. epidermidis infections in hospital settings. Materials and Methods: Skin swabs were taken from seventy two subjects residing in Chennai with healthy skin who showed no visible signs of skin lesions or allergies. S. epidermidis was isolated from 58 samples out of the 72 collected. The presence of ica operon in S. epidermidis isolates was determined by PCR and biofilm production was examined using quantitative tissue culture plate assay. Results: Majority of the samples (47/72; 65.3%) showed pure S. epidermidis growth, (14/72; 19.4%) showed pure Staphylococcus aureus growth and the remainder (11/72; 15.3%) showed mixed growth. Biofilm-forming S. epidermidis were found in the majority of samples (53/58; 91.4%) and ica operon was detected in 19 samples out of 58 (32.8%) which is a significantly higher percentage when compared to other studies conducted at different parts of the globe ( P = 0.0003). Conclusion: We inferred that ica operon and biofilm-forming S. epidermidis are common in the healthy skin of individuals in Tamil Nadu. Measures have to be taken to reduce the risk of hospital-acquired S. epidermidis infections.
ABSTRACT
To determine the relationship between the intercellular adhesion operon (ica) and the biofilm production in Staphylococcus epidennidis isolates from nosocomial infection, and the affection of ica on the antibiotic susceptibility of the isolates, we collected 106 strains, epidermidis isolates from nosocomial infection specimen to detect their biofilm production by quantitative and qualitative method and investigate the existence of ica operon by PCR. The minimal inhibitory concentration (MIC) to erythromycin, ampicillin, cefoxitin, ceftriaxone, teco-planin, ciprofloxacin, tetracycline, trimethoprim-sulfamethoxazole and vancomycin were tested. Among the isolates, 33 (31. 1% ) of them were detected out carrying ica operon. The rate of biofilm production of the ica-posi-tive isolates was higher than that of the ica-negative (P =0. 001) . By adding glucose and NaCl into the culture the detection rate of biofilm production could be increased. The antibiotic susceptibility of the plankton cells of ica-positive isolates to erythromycin, cefoxitin and ceftriaxone , except ampicillin, ciprofloxacin, tetracycline and tremethoprim-sulfamethoxazole, were lower than those of ica-negative isolates. This study showed that the existence of ica operon was close related to the biofilm formation in 5. epidermidis isolates from nosocomial infection. However, the mechanism of antibiotic resistance of the strains inside the biofilm still needed to be illustrated.