Phenotypic and genotypic characterization of coagulase negative staphylococci (CoNS) other than Staphylococcus epidermidis isolated from ocular infections.
OBJECTIVE
The clinical significance of many species belonging to coagulase-negative staphylococci (CoNS) other than Staphylococcus epidermidis has been increasingly recognized. The present study attempted the characterization of non-S. epidermidis CoNS isolates of ocular origin.


METHODS
The isolates were characterized phenotypically by analytical profile index (API) and genotypically by fluorescent amplified fragment length polymorphism (FAFLP). In addition, the presence of genes that are likely to enhance virulence such as biofilm related genes (icaA and icaB) and methicillin resistance (mecA) were detected.


RESULTS
API identified seven different species with an identification score varying from 44% to 99%. S. haemolyticus and S. xylosus species identified by API showed good API scores when compared with all other species identified. FAFLP generated 12 clusters from all the isolates and appeared to be more discriminatory. API identification results corresponded well with the FAFLP results only in six clusters. Nearly 40% of isolates showed the presence of mecA and icaAB genes.


CONCLUSIONS
Identification results of these two methods corresponded only in 48.4% of the isolates suggesting that the battery of tests using API were not sufficient enough to identify all the species of CoNS. Therefore, it is sensible to rely on two or more identification methods particularly when API species identification has a lower score. FAFLP genotyping appears to be a reliable and rapid alternative identification method for CoNS that can be used in conjunction with any other phenotypic method.
Department of Biotechnology, School of Life Sciences, Pondicherry University, Puducherry, India.
Abhijith R
AR
Makki
Savitri
S
Sharma
Aparna
A
Duggirala
K
K
Prashanth
Prashant
P
Garg
Taraprasad
T
Das
D000581:Amidohydrolases / Q000235:genetics; D054458:Amplified Fragment Length Polymorphism Analysis; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D018441:Biofilms; D003030:Coagulase / Q000235:genetics*; D015818:Eye Infections, Bacterial / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D013203:Staphylococcal Infections / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D041162:Staphylococcus haemolyticus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
D001426:Bacterial Proteins; D003030:Coagulase; C487495:MecA protein, Staphylococcus epidermidis; D000581:Amidohydrolases; C497363:poly-N-acetylglucosamine deacetylase