High-resolution genome profiling differentiated Staphylococcus epidermidis isolated from patients with ocular infections and normal individuals.
OBJECTIVE
To investigate the potential phenotypic and genetic differences among the Staphylococcus epidermidis isolates obtained from control subjects (lower conjunctival sac; n = 14) with those from patients with keratitis (corneal scrapings; n = 18) or endophthalmitis (vitreous; n = 24).


METHODS
Biofilm-forming capacity was detected by PCR for the icaAB gene and phenotyping by microtiter plate assay and congo red agar plate. Genotyping was performed by using fluorescence-amplified fragment length polymorphism (FAFLP) and in silico analysis of the FAFLP profiles.


RESULTS
Biofilm phenotyping (congo red agar/microtiter plate) differentiated disease-causing strains from control subjects. PCR assays (mecA, icaAB) were not useful in differentiating disease-causing strains from that of control subjects. The biofilm-forming capability appeared more critical in the pathogenesis of keratitis than in that of endophthalmitis. Cluster analysis of FAFLP data generated 11 clusters comprising 4 major clusters (I, II, III, and V) and 7 minor ones. FAFLP analysis clearly showed clustering of most of the commensal isolates in cluster I, separate from keratitis and endophthalmitis isolates. In silico analysis mapped signature bands to genes such as ebh, tagD, ptsI, and sepA, which might have a significant role in transforming less virulent populations of S. epidermidis to more virulent ones.


CONCLUSIONS
The population dynamics of S. epidermidis revealed that there are significant genetic variations that can be detected through FAFLP between ocular disease causing isolates and the commensal population.
Duggirala
Aparna
A
L. V. Prasad Eye Institute, Hyderabad, India.
Kenchappa
Prashanth
P
Sharma
Savitri
S
Peeters
Justine K
JK
Ahmed
Niyaz
N
Garg
Prashant
P
Das
Taraprasad
T
Hasnain
Seyed E
SE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000254:growth & development; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis; D009877:Endophthalmitis / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000382:microbiology*; D005260:Female; D005453:Fluorescence; D020869:Gene Expression Profiling; D014644:Genetic Variation; D016680:Genome, Bacterial; D006801:Humans; D007223:Infant; D007634:Keratitis / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D013203:Staphylococcal Infections / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification
D004269:DNA, Bacterial