Speciation and Biofilm Production of Coagulase Negative Staphylococcal Isolates from Clinically Significant Specimens and their Antibiogram

• Main Authors: S. S. Vijayasri Badampudi, Surya Kirani KRL, RajyalakshmiGunti
• Format: Article
• Language: English
• Published: Krishna Institute of Medical Sciences University 2016-04-01
• Series: Journal of Krishna Institute of Medical Sciences University
• Subjects: Coagulase Negative Staphylococcus; Speciation; Methicillin resistance; Biofilm; Congo Red.
• Online Access: http://www.jkimsu.com/jkimsu-vol5no2/JKIMSU,%20Vol.%205,%20No.%202,%20April-June%202016%20Page%2069-78.pdf
• ISSN: 2231-4261; 2231-4261

Background: Coagulase Negative Staphylococci (CONS) are increasingly recognized as significant nosocomial pathogens. Their ability of biofilm formation and multiple drug resistance are causing serious human infections. Aim and Objectives: To isolate, identify, speciate clinically significant CONS from various specimens, to study antibiotic resistance pattern and biofilm production. Material and Methods: Specimens were collected aseptically, processed and identified upto the species level by a simple scheme of tests urease, novobiocin resistance, mannose and mannitol fermentation, ornithine decarboxylase. Antibiotic sensitivity was done with special reference to methicillin resistance. Biofilm formation was detected by Congo Red Agar (CRA) method and Tube Method (TM). Results: Study groupOf 100 isolates majority were pus (40), followed by urine (28), blood (16), CSF (5), body fluids (4) and catheter tips and implants (7). The most common species isolated was S. epidermidis (40%) followed by S. haemolyticus (26%), S. saprophyticus (15%), S. schleiferi (13%), S. simulans (2%), S. cohnii (2%) and S. warneri and S. capitis each 1%. Resistance to penicillin was 91% followed by ampicillin (79%), cotrimoxazole (67%). Methicillin resistance was 72%. Biofilm producers were 69% by CRAmethod and 33% by TM with majority species S. epidermidis (82.5%- CRA and 55%-TM). Biofilm production was significantly associated with MRCONS (p value 0.0036). Control group-Of 30 isolates were S. epidermidis 66.6% followed by S. haemolyticus (16.66%). Biofilm producers were 53.33% by CRA method and 26.65% by TM with majority species S. epidermidis (65%-CRA and 30%-TM).Methicillin resistance was 26.6%. Conclusion: Clinical significance of CONS is increasing day by day, so there is a need for accurate identification to species level and their antibiogram to avoid multidrug resistance. Biofilm producing CONS species pose a risk and CRA method for screening biofilm can be used in all conventional microbiology laboratories.