title: Methicillin-Susceptible Teicoplanin-Resistant Staphylococcus haemolyticus Isolate from a Bloodstream Infection with Novel Mutations in the tcaRAB Teicoplanin Resistance Operon.
abstract: Staphylococcus haemolyticus is a coagulase-negative staphylococcus that is frequently isolated from blood cultures. Here, we report a case of methicillin-susceptible S. haemolyticus that is resistant to teicoplanin (TEC) and heteroresistant to vancomycin (VAN). The isolate was susceptible to cefoxitin and resistant to TEC by Etest. Population analysis profile-area under the curve analysis confirmed the presence of a VAN heteroresistant subpopulation. Next-generation sequencing analysis of the genome revealed the presence of blaZ and msr(A), which encode cross-resistance to macrolide, lincosamide, and streptogramin B, and the quinolone resistance-conferring gene norA. In addition, several amino acid substitutions were observed in the TEC resistance operon tcaRAB, including I3N, I390N, and L450I in tcaA and L44V, G52V, and S87P in tcaR, as well as in the transpeptidase encoding gene walK (D336Y, R375L, and V404A) and L315 and P316 in graS. We hypothesized that this combination of mutations could confer TEC resistance and reduced VAN susceptibility.
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Yamuna Devi
authors.initials: YD
authors.lastname: Bakthavatchalam
authors.affiliation: Department of Medicine (Unit II), Christian Medical College.
authors.forename: Thambu David
authors.initials: TD
authors.lastname: Sudarsanam
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Babu
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Elakkiya
authors.initials: E
authors.lastname: Munuswamy
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Dhiviya Prabaa
authors.initials: DP
authors.lastname: Muthuirulandi Sethuvel
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Naveen Kumar
authors.initials: NK
authors.lastname: Devanga Ragupathi
authors.affiliation: Department of Clinical Microbiology, Christian Medical College.
authors.forename: Balaji
authors.initials: B
authors.lastname: Veeraraghavan
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology*; D000073537:Biological Variation, Population; D002440:Cefoxitin / Q000494:pharmacology; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D008712:Methicillin / Q000494:pharmacology*; D008875:Middle Aged; D020125:Mutation, Missense; D009876:Operon; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology*; D041162:Staphylococcus haemolyticus / Q000187:drug effects* / Q000302:isolation & purification; D017334:Teicoplanin / Q000494:pharmacology*; D000073336:Whole Genome Sequencing
chemical_list: D000900:Anti-Bacterial Agents; D017334:Teicoplanin; D002440:Cefoxitin; D008712:Methicillin
keywords: Staphylococcus haemolyticus; tcaRAB; vraSR