Atcc 35984

Gram-negative Escherichia coli CSH36 (E. coli, Coli Genetic
Stock Center, Yale University, CT, USA) and Pseudomonas fluorescens ATCC 13525 (P. fluorescens, American Type Culture
Collection, VA, USA) and Gram-positive Listeria innocua CECT 910 (L. innocua, Spanish Type Culture Collection,
Spain) and Staphylococcus epidermidis ATCC 35984
(S. epidermidis, American Type Culture Collection,
VA, USA) were used in this study. The bacteria were grown for 16–18
h in Tryptic Soy Agar (TSA) and subcultured every week up to five
passages. In each assay, bacteria were harvested from TSA plates,
inoculated into 10 mL of Tryptic Soy Broth (TSB, Oxoid, Basingstoke,
UK), and incubated for 16–18 h at the optimum growth temperature
(30 °C for P. fluorescens and 37 °C for
the remaining bacteria), at 180 rpm. Then, the cultures were diluted
in TSB to an optical density of 0.1 at 600 nm (OD₆₀₀) and
grown up to the exponential phase, at the previously described conditions.
The final bacterial concentration was set to OD₆₀₀ = 0.15
(P. fluorescens) or OD₆₀₀ = 0.1 (remaining
bacteria).

Twenty-three non-duplicate S. epidermidis were isolated from patients with a variety of ocular infections at L.V. Prasad Eye Institute, Bhubaneswar, India, during 2007–2011. These isolates were from patients with keratitis (n = 13), endophthalmitis (n = 2), conjunctivitis (n = 2), marsupialization of cyst (n = 1), chronic dacryocystitis (n = 1), traumatic cataract (n = 1), canaliculitis (n = 1), blepharitis (n = 1) and graft infiltrate (n = 1). Also, 29 strains were isolated from asymptomatic healthy conjunctiva. The study was conducted following the guidelines mentioned in the Declaration of Helsinki. All the 52 isolates were identified by using biochemical tests including Gram staining, catalase production, fermentation of glucose and mannitol and ID32 STAPH strips using ATB™ NEW v.1.0.0 software on an ATB™ reader (bioMerieux, France). The amplification of S. epidermidis nuc gene confirmed the identity of isolates (Hirotaki et al., 2011 (link)). S. epidermidis strains ATCC 35984 and ATCC 12228 obtained from American Type Culture Collection (ATCC, Manassas, VA), were used as controls in this study. Staphylococcus aureus ATCC 25293 and Pseudomonas aeruginosa ATCC 27853 was used as quality control strains for antibiotic susceptibility testing.