Fluorescent amplified fragment length polymorphism (FAFLP) genotyping demonstrates the role of biofilm-producing methicillin-resistant periocular Staphylococcus epidermidis strains in postoperative endophthalmitis.
BACKGROUND
An observational case series was used to study the virulence characteristics and genotypes of paired Staphylococcus epidermidis isolates cultured from intraocular samples and from periocular environment of patients with postcataract surgery endophthalmitis.


METHODS
Eight S. epidermidis isolates were obtained from three patients (2 from patients #1 and 2 and 4 from patient #3) whose vitreous and/or anterior chamber (AC) specimens and preoperative lid/conjunctiva samples were culture positive. Cultures were identified by API-Staph phenotypic identification system and genotypically characterized by Fluorescent Amplified Fragment Length Polymorphism (FAFLP) and checked for their antimicrobial susceptibility. The isolates were tested for biofilm-production and methicillin-resistance (MR) by PCR amplification of icaAB and mecA gene respectively.


RESULTS
Four out of eight S. epidermidis strains showed multiple drug resistance (MDR). All the eight strains were PCR positive for mecA gene whereas seven out of eight strains were positive for icaAB genes. In all three patients FAFLP typing established vitreous isolates of S. epidermidis strains to be indistinguishable from the strains isolated from the patient's conjunctival swabs. However, from patient number three there was one isolate (1030b from lid swab), which appeared to be nonpathogenic and ancestral having minor but significant differences from other three strains from the same patient. This strain also lacked icaAB gene. In silico analysis indicated possible evolution of other strains from this strain in the patient.


CONCLUSIONS
Methicillin-resistant biofilm positive S. epidermidis strains colonizing the conjunctiva and eyelid were responsible for postoperative endophthalmitis (POE).
Kenchappa
Prashanth
P
Laboratory of Molecular and Cell Biology, Centre for DNA Fingerprinting and Diagnosits, Nacharam, Hyderabad-500 076, India. prashant@cdfd.org.in
Duggirala
Aparna
A
Ahmed
Niyaz
N
Pathengay
Avinash
A
Das
Taraprasad
T
Hasnain
Seyed E
SE
Sharma
Savitri
S
D000328:Adult; D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000254:growth & development*; D002387:Cataract Extraction / Q000009:adverse effects*; D003228:Conjunctiva / Q000382:microbiology; D009877:Endophthalmitis / Q000209:etiology / Q000382:microbiology*; D005123:Eye / Q000382:microbiology*; D005143:Eyelids / Q000382:microbiology; D005260:Female; D005453:Fluorescence; D005838:Genotype; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length; D013212:Staphylococcus epidermidis / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*