Identification of Major Sequence Types among Multidrug-Resistant Staphylococcus epidermidis Strains Isolated from Infected Eyes and Healthy Conjunctiva

We examined the presence of virulence and antibiotic resistance genes, SCCmec types and determined the genomic diversity among ocular S. epidermidis isolates (patients-23, healthy controls-29). PCR determined the presence of antibiotic resistance genes, virulence genes and SCCmec types among all isolates. MLST and PFGE determined the genomic relatedness among them. All isolates of S. epidermidis showed resistance to at least one class of antibiotics of which 48 isolates were multidrug resistant and carried ARGs. Thirty-five isolates were methicillin resistant and carried mecA gene. Majority of the isolates were resistant to fluoroquinolones and showed mutation in gyrA, parC, and parE genes, however, few isolates showed additional novel mutations in parC gene. Of the MRSE strains, 17 strains carried SCCmec type IV, four type V, two type II, and two UT4. Seven strains carried novel combination of ccr complex and SCCmercury element, not reported earlier. All the S. epidermidis strains harbored icaA and icaD genes, 47 carried ACME operon, and 50 contained IS256. A noteworthy finding was the presence of ST179 among 43% of infected eye isolates an observation rarely reported among S. epidermidis. PFGE and MLST analysis showed genomic diversity among them. Statistical analysis suggests that few healthy conjunctiva isolates had characteristics similar to infected eye isolates. S. epidermidis strains carrying mecA gene are multidrug resistant, virulent and diverse irrespective of sources of isolation. IS256 cannot be used as marker to differentiate isolates of infected eye from healthy conjunctiva

Thiomonas bhubaneswarensis sp. nov., an obligately mixotrophic, moderately thermophilic, thiosulfate-oxidizing bacterium

A novel aerobic, obligately mixotrophic, moderately thermophilic, thiosulfate-oxidizing bacterium, S10<SUP>T</SUP>, was isolated from hot-spring sediment samples collected from Atri, Bhubaneswar, India. The cells of this isolate stained Gram-negative and were strictly aerobic, non-sporulating, rod-shaped and motile with a single polar flagellum. Strain S10<SUP>T</SUP> was positive for oxidase and catalase activities. It was capable of utilizing thiosulfate under mixotrophic growth conditions. Mixotrophic growth was observed at pH 6.0-8.5 and 25-45 °C; optimum growth occurred at pH 7.5-8.0 and 30-37 °C. The major cellular fatty acids were C<SUB>12:0</SUB> 3-OH, C<SUB>16:1</SUB>ω7c, C<SUB>16:0</SUB>, C<SUB>17:0</SUB> cyclo, C<SUB>18:1</SUB>ω7c and C19:0 cyclo ω8c. The DNA G+C content of strain S10<SUP>T</SUP> was 64.8 mol%. 16S rRNA gene sequence analysis indicated that the bacterium clustered within the radiation of the genus Thiomonas and showed 98.0% similarity with Thiomonas perometabolis ATCC 23370<SUP>T</SUP> and Thiomonas intermedia ATCC 15466<SUP>T</SUP>. However, DNA-DNA reassociation values of strain S10<SUP>T</SUP> with Thiomonas perometabolis JCM 20426<SUP>T</SUP> and Thiomonas intermedia JCM 20425<SUP>T</SUP>, its nearest phylogenetic relatives, were 46 and 39%, respectively. On the basis of phenotypic, physiological and chemotaxonomic properties, 16S rRNA gene sequence analysis and DNA-DNA reassociation studies, it is proposed that strain S10<SUP>T</SUP> represents a novel species of the genus Thiomonas, Thiomonas bhubaneswarensis sp. nov.; the type strain is S10<SUP>T</SUP> (=DSM 18181<SUP>T</SUP> =JCM 14806<SUP>T</SUP>)