Comprehensive antimicrobial susceptibility testing of a large collection of clinical strains of Aggregatibacter actinomycetemcomitans does not identify resistance to amoxicillin

• AIM: The present study aims to determine the susceptibility of Aggregatibacter actinomycetemcomitans to amoxicillin by investigating a large collection of oral strains of diverse geographical origin.METHODS: Two hundred and fifty-seven A. actinomycetemcomitans strains were serotyped using a multiplex polymerase chain reaction, and minimal inhibitory concentration (MIC) values of amoxicillin were determined using the agar dilution method (range 0.25 to 8.0 mg/L). The plates were spot-wise inoculated with approximately 104 colony-forming units, incubated in 5% CO2 at 37 C°, and visually inspected after 24 and 48 hours. A MIC ≤ 2.00 mg/L was categorised as susceptible using EUCAST interpretative criteria for Haemophilus species.RESULTS: Amoxicillin MIC-values varied from 0.25 mg/L to 2.00 mg/L, and all tested strains, including strains previously reported as resistant, were susceptible to amoxicillin. The MIC50 was 1.00 mg/L and the MIC90 was 2.00 mg/L.CONCLUSION: Meticulous investigation of strains including isolates previously reported as resistant could not confirm the emergence of resistance to β-lactams in A. actinomycetemcomitans. Based on the present in vitro results, amoxicillin can be considered a key oral antimicrobial agent for treatment of A. actinomycetemcomitans. This article is protected by copyright. All rights reserved.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Odontologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Dentistry (hsv//eng)

Nyckelord

EUCAST

Antimicrobial resistance

agar dilution method

breakpoints

β-lactams

mikrobiologi

Microbiology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)