Studies on prevalence of biofilm associated genes and primary observation on sasX gene in clinical isolates of coagulase negative staphylococci (CoNS)

Abstract

Coagulase negative staphylococci (CoNS) are nosocomial pathogens that cause indwelling medical device associated infections due to its biofilm forming potential and multiple antibiotic resistance. The current study focused on species identification, antibiotic resistance profile and molecular basis of biofilm formation and attachment of CoNS isolated from clinical samples. Along with this, molecular screening for mecA and newly identified surface colonization protein encoded by sasX gene was also conducted. S. epidermidis (n = 19, 47%) was identified as the most prevalent CoNS species and very interestingly two biofilm forming, mecA positive S. epidermidis isolates were found to carry all the biofilm associated genes screened in this study, which indicates its potential to form the strong biofilm. Another novel observation of the study is the detection of sasX gene in one biofilm positive S. epidermidis isolate. The study also identified one doxycycline resistant mecA positive, multidrug resistant S. haemolyticus isolate. In conclusion, the study signifies the existence of multiple biofilm related genes, multidrug resistance and the presence of sasX gene among clinical isolates of CoNS.

Genotype Diversity and Evaluation of Biofilm Formation in sasX Positive Methicillin-Resistant Staphylococcus aureus

“…Amongst 180 confirmed MRSA strains, 23 isolates (12.6%) were sasX positive. The results were in agreement with that of Li et al (12 (11). In this study, a significant correlation was not found between clinical samples and sasX positive isolates.…”

“…One of these important proteins is sasX that has many different roles in this process, including biofilm formation, which helps the bacteria in producing micro colonies and adhesion on the surfaces and bacterial resistance against unexpected conditions (11). Regarding recent studies, SasX had an important role in the pathogenesis of the asian population and ST239 colon (8) and based on its importance, even new studiese have focused on the role of SasX protein in immunization and vaccinaton (9).…”

“…Biofilm assays were performed according to microtiter plate assay (11). Briefly, the isolates were grown in TSB (Merck Co., Germany) 1% Glc at 37°C for 18 hours.…”

Studies on coexistence of mec gene, IS256 and novel sasX gene among human clinical coagulase-negative staphylococci

“…Its existence in S. epidermidis was already reported in our previous work (Soumya et al 2016). However, the presence of this gene in S. hemolyticus and S. saprophyticus species is a novel report and this was confirmed by sequence analysis which showed 100% percentage identity to the LPXTG motif of S. aureus TW20.…”

“…SasX provide advantages to the organism due to its role in increased nasal colonization onto host, immune evasion, virulence, bacterial aggregation, biofilm formation and even attachment to the abiotic surfaces (Holden et al 2010; Li et al 2012; Otto 2012). In our previous study, we could identify the presence of sas X gene in S. epidermidis (Soumya et al 2016). Hence in this study, prevalence of sas X gene was analyzed among methicillin-resistant clinical isolates of coagulase-negative staphylococci to investigate its relation to mec A gene and IS256.…”