Dixon J M, Lipinski A E
Antimicrob Agents Chemother. 1972 Apr;1(4):333-9. doi: 10.1128/AAC.1.4.333.
Ten (0.05%) of 18,628 strains of Streptococcus pyogenes isolated from clinical specimens in the 3 years 1968 to 1970 were resistant to lincomycin and erythromycin. All 10 strains were highly resistant to lincomycin, having minimal inhibitory concentration (MIC) values of 200 mug/ml. There were two degrees of resistance to erythromycin: four strains were highly resistant, having MIC values of 200 mug or more/ml; and six strains showed slight resistance, MIC values being 0.78 to 1.56 mug/ml. There was no known epidemiological relationship between any of the patients infected with the resistant strains, which belonged to a variety of T serotypes. A zonal pattern of resistance to lincomycin occurred in four strains, all of which were only slightly resistant to erythromycin. After incubation for 24 hr in a twofold dilution series of lincomycin in broth, the strains grew in 0.05 mug or less/ml and in 50 and 100 mug/ml, but not in intermediate concentrations. Tests in agar indicated that the bacterial population of one strain, but not of the other three, was homogeneous in respect to its ability to grow readily in low and high, but not in intermediate, concentrations. The zone phenomenon is of significance in the clinical laboratory, since unawareness of it might result in a highly resistant strain being regarded as susceptible to lincomycin in tube or plate MIC tests that do not include sufficiently high concentrations of lincomycin.
1968年至1970年这3年间，从临床标本中分离出的18628株化脓性链球菌中有10株（0.05%）对林可霉素和红霉素耐药。所有10株菌对林可霉素高度耐药，其最低抑菌浓度（MIC）值为200μg/ml。对红霉素有两种耐药程度：4株高度耐药，MIC值为200μg或更高/ml；6株显示轻度耐药，MIC值为0.78至1.56μg/ml。感染耐药菌株的患者之间不存在已知的流行病学关系，这些菌株属于多种T血清型。4株菌出现对林可霉素的耐药带型，所有这些菌株对红霉素仅轻度耐药。在肉汤中用林可霉素的两倍稀释系列培养24小时后，这些菌株在0.05μg或更低/ml以及50和100μg/ml中生长，但在中间浓度中不生长。琼脂试验表明，其中一株菌的细菌群体在低浓度和高浓度（但不是中间浓度）下易于生长的能力方面是均匀的，而其他三株菌则不是。这种带型现象在临床实验室中具有重要意义，因为如果不了解它，在不包括足够高浓度林可霉素的试管或平板MIC试验中，可能会将高度耐药菌株视为对林可霉素敏感。
