First Report of the Emergence of mecC Gene and CC8/ST239 Tigecycline-Resistant Staphylococcus aureus Clonal Lineage Isolated from Chronic Suppurative Otitis Media

 Staphylococcus aureus is one of the most significant bacteria involved in ear infections. However, insights into the molecular attributes of S. aureus collected from patients with chronic otitis media have yet to be reported in Iran.

 The objective of this study was to assess the molecular characteristics of S. aureus isolated from patients with chronic otitis media.

 A total of 55 S. aureus strains retrieved from patients with chronic otitis media were analyzed by the disk diffusion method and polymerase chain reaction (PCR) to identify the nucA gene. Isolates were genetically classified using the coagulase typing method. S. aureus protein A (spa) typing, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing (MLST) were performed on isolates with resistance to specific antibiotics.

 Overall, out of 55 S. aureus isolates, resistance to mupirocin, fusidic acid, and tigecycline was identified in 12.7%, 5.4%, and 3.6% of isolates, respectively. Fusidic acid-resistant isolates belonged to ST5-SCCmecII/t002/coaII. Two tigecycline-resistant isolates belonged to CC8/ST239-SCCmecIII/t234/coaVIII. One positive mecC isolate belonged to the CC/ST130-SCCmecXI/t843/coaIII clone. Isolates with the iMLSB phenotype belonged to CC/ST80-SCCmecIV/t044/coaII (4 isolates), CC8/ST239-SCCmecIII/t388/coaVI (3 isolates), and CC8/ST8-SCCmecIV/t008/coaIII (1 isolate).

 Our results indicated that S. aureus isolated from patients with chronic otitis media possesses a unique molecular profile with a high percentage of resistance to multiple medications. These findings suggest that resuming the molecular analysis to improve the control and prevention of ear infections related to S. aureus is necessary.