Microbiology and antimicrobial susceptibility of otitis externa: a changing pattern of antimicrobial resistance

J Laryngol Otol. 2018 Apr;132(4):314-317. doi: 10.1017/S0022215118000191. Epub 2018 Feb 12.

Abstract

Objective: Otitis externa is a common presentation to secondary care otolaryngology clinics. Despite this, few studies have investigated the microbiology and antimicrobial resistance of otitis externa. This study aimed to examine these issues.

Methods: Analysis identified 302 swabs taken from 217 patients (100 male, 117 female), between 1 January 2015 and 30 March 2016, at our rapid access otolaryngology clinic.

Results: In total, 315 organisms were isolated; the most frequent was Pseudomonas aeruginosa (31.1 per cent), followed by candida species (22.9 per cent) and Staphylococcus aureus (11.7 per cent). P aeruginosa was sensitive to ciprofloxacin in 97.7 per cent of cases and to gentamicin in 78.4 per cent.

Conclusion: Compared with studies worldwide, the relative proportions of different organisms causing otitis externa and the patterns of antimicrobial resistance differ. Increasing resistance of P aeruginosa to aminoglycosides demonstrates a changing pattern of antimicrobial resistance that has not been previously reported. Reassuringly, quinolone antibiotics remain highly effective when treating P aeruginosa.

Keywords: Antimicrobial Drug Resistance; Microbiology; Otitis Externa.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Aminoglycosides / administration & dosage
  • Anti-Bacterial Agents / administration & dosage
  • Anti-Bacterial Agents / pharmacology*
  • Candida / isolation & purification
  • Candidiasis / drug therapy
  • Candidiasis / microbiology
  • Ciprofloxacin / administration & dosage
  • Ciprofloxacin / pharmacology
  • Drug Resistance, Bacterial / physiology*
  • Female
  • Gentamicins / administration & dosage
  • Gentamicins / pharmacology
  • Humans
  • Male
  • Microbial Sensitivity Tests / methods
  • Middle Aged
  • Otitis Externa / drug therapy
  • Otitis Externa / microbiology*
  • Pseudomonas Infections / drug therapy
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / isolation & purification
  • Quinolones / administration & dosage
  • Quinolones / pharmacology
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / microbiology
  • Staphylococcus aureus / isolation & purification

Substances

  • Aminoglycosides
  • Anti-Bacterial Agents
  • Gentamicins
  • Quinolones
  • Ciprofloxacin