Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from symptomatic men attending the Nanjing sexually transmitted diseases clinic (2011–2012): genetic characteristics of isolates with reduced sensitivity to ceftriaxone

Table 1 In vitro antimicrobial susceptibility of Neisseria gonorrhoeae : clinical isolates (n = 334)

Antimicrobial breakpoints (susceptible/resistant [mg/L]) ^a	No. (%)			MIC (mg/L)
Antimicrobial breakpoints (susceptible/resistant [mg/L]) ^a	Susceptible	Intermediate	Resistant	Range	MIC ₅₀	MIC ₉₀
Penicillin G (S ≤ 0.06/R ≥ 2)	0	108 (32.3)	226 (67.7)	0.125 to >8	2	>8
Tetracycline (S ≤ 0.25/R ≥ 2)	2 (0.6)	5 (1.5)	327 (97.9)	0.25 to >16	8	>16
Ciprofloxacin (S ≤ 0.06/R ≥ 1)	0	4 (1.2)	330 (98.8)	≤0.25 to >8	>8	>8
Spectinomycin (S ≤ 32/R ≥ 128)	334 (100)	0	0	≤4 to 32	16	32
Ceftriaxone (S ≤ 0.25)	334 (100)	-	-	0.004 to 0.25	0.03	0.06

^aAntimicrobial breakpoints that distinguish susceptible from resistant gonococcal isolates (CLSI Document M07-A9 (M100-S22) [35]. MIC: minimum inhibitory concentration.