Penland R L, Wilhelmus K R
Sid W. Richardson Ocular Microbiology Laboratory, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.
Cornea. 1998 Mar;17(2):135-40. doi: 10.1097/00003226-199803000-00003.
Approximately 15-20% of Streptococcus pneumoniae clinical isolates in the United States are not susceptible to penicillin. Isolates with a minimum inhibitory concentration (MIC) of 0.12-1.0 mg/ml are intermediately resistant, and those with an MIC > 2.0 microg/ml are classified as having high-level penicillin resistance.
We determined the proportion of penicillin-resistant S. pneumoniae recovered from ocular and periocular infections from 1976 through 1995, compared these cases with penicillin-susceptible controls, and evaluated the susceptibility of penicillin-resistant isolates to selected cephalosporins and fluoroquinolones.
MICs for cephalothin, ceftazidime, ciprofloxacin, and ofloxacin were determined for available isolates by the E test. We performed a case-comparison study to evaluate differences between patients with penicillin-susceptible and -nonsusceptible ocular pneumococcal infections.
Of 173 ocular isolates of S. pneumoniae isolated in the 20-year period, 12 (7%) were not susceptible to penicillin, including eight (5%) intermediate isolates and four (2%) highly resistant isolates. Penicillin-intermediate and -resistant pneumococci were recovered at a rate of none of 46 isolates from 1976 through 1980, one (4%) of 25 from 1981 through 1985, one (2%) of 51 from 1986 through 1990, and 10 (20%) of 51 from 1991 through 1995 (p < 0.0004). We found no significant differences in presenting characteristics between patients with ocular infections due to penicillin-susceptible pneumococci and those caused by nonsusceptible strains. All retested isolates with intermediate susceptibility to penicillin had a cephalothin MIC < or = 1.5 microg/ml, and all retested isolates with high-level penicillin resistance had a cephalothin MIC > or = 4 microg/ml. The ceftazidime MIC for all penicillin-resistant isolates was > or = 24 microg/ml. All penicillin-nonsusceptible isolates had MICs < or = 1.5 microg/ml for ciprofloxacin and < or = 3 microg/ml for ofloxacin.
Penicillin resistance has recently emerged among ocular S. pneumoniae. Cephalothin, ciprofloxacin, and ofloxacin have good activity against some ocular isolates with intermediate penicillin susceptibility, although another agent such as vancomycin may be needed for pneumococci with high-level penicillin-resistance.
在美国，约15% - 20%的肺炎链球菌临床分离株对青霉素不敏感。最低抑菌浓度（MIC）为0.12 - 1.0毫克/毫升的分离株为中度耐药，MIC > 2.0微克/毫升的分离株被归类为高水平青霉素耐药。
我们确定了1976年至1995年从眼部和眼周感染中分离出的耐青霉素肺炎链球菌的比例，将这些病例与青霉素敏感对照进行比较，并评估耐青霉素分离株对选定头孢菌素和氟喹诺酮类药物的敏感性。
通过E试验确定可用分离株对头孢噻吩、头孢他啶、环丙沙星和氧氟沙星的MIC。我们进行了一项病例对照研究，以评估青霉素敏感和不敏感的眼部肺炎球菌感染患者之间的差异。
在20年期间分离出的173株眼部肺炎链球菌中，12株（7%）对青霉素不敏感，包括8株（5%）中度耐药分离株和4株（2%）高度耐药分离株。1976年至1980年的46株分离株中无一例耐青霉素中度和耐药肺炎球菌，1981年至1985年的25株中有1株（4%），1986年至1990年的51株中有1株（2%），1991年至1995年的51株中有10株（20%）（p < 0.0004）。我们发现青霉素敏感肺炎球菌引起的眼部感染患者与不敏感菌株引起的患者在临床表现特征上没有显著差异。所有对青霉素中度敏感的重新检测分离株头孢噻吩MIC≤1.5微克/毫升，所有对青霉素高水平耐药的重新检测分离株头孢噻吩MIC≥4微克/毫升。所有耐青霉素分离株的头孢他啶MIC≥24微克/毫升。所有对青霉素不敏感的分离株对环丙沙星的MIC≤1.5微克/毫升，对氧氟沙星的MIC≤3微克/毫升。
眼部肺炎链球菌中最近出现了青霉素耐药情况。头孢噻吩、环丙沙星和氧氟沙星对一些青霉素中度敏感的眼部分离株有良好活性，尽管对于高水平青霉素耐药的肺炎球菌可能需要另一种药物如万古霉素。
