Table 8.

Susceptibility of M. catarrhalis to 23 selected antimicrobial agentsa

Antimicrobial agent and phenotype (no. of isolates)bMIC (μg/ml)
Range50%90%
Amoxicillin
 All (444)≤0.06–>324.016
 β-Lactamase+ (416)≤0.06–>324.016
 β-Lactamase− (28)≤0.06–0.5≤0.030.25
Amoxicillin-clavulanate
 All (444)≤0.03–40.250.25
 β-Lactamase+ (416)≤0.03–40.250.25
 β-Lactamase− (28)≤0.03–0.5≤0.030.25
Cephalothin
 All (444)0.12–644.016
 β-Lactamase+ (416)0.12–648.016
 β-Lactamase− (28)0.12–80.54.0
Cefaclor
 All (444)≤0.03–81.01.0
 β-Lactamase+ (416)≤0.03–81.01.0
 β-Lactamase− (28)0.12–20.252.0
Loracarbef
 All (444)≤0.015–162.04.0
 β-Lactamase+ (416)≤0.015–162.04.0
 β-Lactamase− (28)0.12–20.122.0
Cefuroxime
 All (444)≤0.03–81.02.0
 β-Lactamase+ (416)≤0.03–81.02.0
 β-Lactamase− (28)≤0.03–20.52.0
Cefprozil
 All (444)0.06–322.08.0
 β-Lactamase+ (416)0.06–322.08.0
 β-Lactamase− (28)0.12–40.54.0
Cefpodoxime
 All (444)0.03–20.51.0
 β-Lactamase+ (416)0.03–21.01.0
 β-Lactamase− (28)0.03–0.50.120.5
Cefixime
 All (444)≤0.25–<8≤0.250.5
 β-Lactamase+ (416)≤0.25–<8≤0.250.5
 β-Lactamase− (28)≤0.25–1≤0.25≤0.25
Ceftibuten
 All (444)≤0.25–>82.04.0
 β-Lactamase+ (416)≤0.25–>82.04.0
 β-Lactamase− (28)≤0.25–4≤0.251.0
Cefotaxime
 All (444)≤0.015–40.51.0
 β-Lactamase+ (416)0.06–40.51.0
 β-Lactamase− (28)≤0.015–10.060.5
Ceftriaxone
 All (444)≤0.015–40.51.0
 β-Lactamase+ (416)≤0.015–40.51.0
 β-Lactamase− (28)≤0.015–0.5≤0.0150.12
Erythromycin
 All (444)≤0.03–80.120.12
 β-Lactamase+ (416)≤0.03–80.120.12
 β-Lactamase− (28)≤0.03–20.122.0
Azithromycin
 All (444)≤0.03–>640.060.12
 β-Lactamase+ (416)≤0.03–>640.060.12
 β-Lactamase− (28)≤0.03–10.060.25
Clarithromycin
 All (444)≤0.03–80.030.06
 β-Lactamase+ (416)≤0.03–80.030.06
 β-Lactamase− (28)≤0.03–10.030.5
Grepafloxacin
 All (444)≤0.004–0.060.0080.015
 β-Lactamase+ (416)≤0.004–0.060.0080.015
 β-Lactamase− (28)≤0.004–0.030.0080.015
Sparfloxacin
 All (444)≤0.004–0.120.0150.015
 β-Lactamase+ (416)≤0.004–0.120.0150.015
 β-Lactamase− (28)≤0.004–0.030.0150.015
Levofloxacin
 All (444)≤0.004–10.030.06
 β-Lactamase+ (416)≤0.004–10.030.06
 β-Lactamase− (28)0.008–0.060.030.06
Ciprofloxacin
 All (444)≤0.004–0.50.030.03
 β-Lactamase+ (416)≤0.004–0.50.030.03
 β-Lactamase− (28)≤0.004–0.060.030.03
Ofloxacin
 All (444)0.015–10.060.06
 β-Lactamase+ (416)0.015–10.060.06
 β-Lactamase− (28)0.015–0.120.060.06
Rifampin
 All (444)≤0.015–>16≤0.0150.03
 β-Lactamase+ (416)≤0.015–>16≤0.0150.03
 β-Lactamase− (28)≤0.015–0.5≤0.0150.25
Tetracycline
 All (444)≤0.5–16≤0.5≤0.5
 β-Lactamase+ (416)≤0.5–16≤0.5≤0.5
 β-Lactamase− (28)≤0.5–4≤0.5≤0.5
SXT
 All (444)<0.125–>40.251.0
 β-Lactamase+ (416)<0.125–>40.251.0
 β-Lactamase− (28)<0.125–1≤0.1251.0
  • a There are no NCCLS breakpoints forM. catarrhalis.

  • b β-Lactamase+, β-lactamase positive; β-Lactamase−, β-lactamase negative.