季铵盐诱导肺炎克雷伯菌外排泵AcrAB-TolC高表达与喹诺酮耐药关系的研究

目的 探讨肺炎克雷伯菌(Kpn) Acr AB-Tol C外排泵参与季铵盐和喹诺酮类抗生素交叉耐药的机制。方法 微量稀释法检测苯扎溴铵诱导前后Kpn临床菌株对苯扎溴铵和环丙沙星(CIP)的最低抑菌浓度(MICs);荧光定量RTPCR技术检测诱导菌株和母株外排泵基因acr AB的mRNA的转录水平。结果 经苯扎溴铵诱导16株临床菌株对其MICs值提高了2倍～8倍; 8株CIP敏感株诱导后5株仍敏感、1株对CIP的MIC=2 mg/L为中介耐药株、2株MIC分别为8 mg/L和16 mg/L成为CIP耐药株; 8株CIP耐药株苯扎溴铵诱导后对CIP的MICs提高2倍～8倍。诱导株acr AB基因相对表达量明显高于母株(P 0. 05)。结论 Acr AB-Tol C外排泵表达与季铵盐和喹诺酮类抗生素交叉耐药有一定的相关性。     

流式细胞仪检测环丙沙星对淋球菌杀菌作用的研究

目的探讨快速检测细菌对药物敏感性的方法.方法淋球菌经环丙沙星作用后,用流式细胞仪检测,进行双参数分析.结果活的淋球菌和死的淋球菌平均荧光通道值分别为0.43和75.7;淋球菌经环丙沙星2μg/ml作用2h后,6株敏感菌的死亡率为(40.1±5.8)%,6株耐药菌的死亡率为(14.1±4.5)%,两者差异显著(P＜0.001);6株敏感菌的死菌相对DNA含量为(47.6±13.6),6株耐药菌的死菌相对DNA含量为(20.9±6.5),两者差异显著(P＜0.05).结论流式细胞仪可以用于快速检测淋球菌对环丙沙星的敏感性.     

连翘对多药耐药鲍氏不动杆菌主动外排泵影响的研究

目的探讨中药连翘对多药耐药鲍氏不动杆菌(ABA)主动外排泵的影响。方法从临床分离的30株多药耐药鲍氏不动杆菌中筛选出对环丙沙星(CIP)外排表型和外排泵编码基因均阳性的9株菌作为试验菌株,应用琼脂对倍稀释法检测连翘水煎剂0、1.25、2.5、5 mg/ml作用后CIP对上述9株菌的最低抑菌浓度(MIC)的变化。结果连翘对ABA1~9的MIC值分别为20、40、10、20、10、10、20、40、20 mg/ml;5 mg/ml和2.5 mg/ml组与0 mg/ml组比较,差异有统计学意义(P<0.05),1.25 mg/ml组与0 mg/ml组比较,差异无统计学意义。结论连翘水煎剂可抑制鲍氏不动杆菌的主动外排泵,对改善鲍氏不动杆菌对CIP的耐药性具有一定的作用。     

199株淋球菌对环丙沙星和头孢三嗪的敏感性测定

目的 了解南宁地区淋球菌对环丙沙星,头孢三嗪的敏感性。方法 采用琼脂稀释法分别测定环丙沙星、头孢三嗪对199株淋球菌的最小抑菌浓度。结果 环丙沙星MIC范围为0．002－2mg/L,其中1999年MIC范围为0．25－≥16mg/L;14．5％菌株对环丙沙星敏感,41．71％为低度敏感,43．72％为耐药,其中1999年有4株淋球菌MIC≥16mg/L。头孢三嗪MIC为0．02－1mg/L,MIC50为0．03mg/L,MIC90为0．5mg/L;55.28％菌株对头孢三嗪敏感,39.20%为低度敏感,5．53％为耐药。其中,1999年末发现耐药菌株。结论 南宁地区已经不能把环丙沙星作为治疗淋病患者的首选药物;头孢三嗪是否仍能作为治疗淋病的一线药物,尚需进一步研究。     

淋球菌对4种抗生素敏感性的研究

[目的 ]研究淋球菌对 4种抗生素的敏感性。 [方法 ] 2 0 0 1年 1月至 2 0 0 2年 6月分离出 2 3 2株淋球菌 ,应用琼脂稀释法测定青霉素、环丙沙星、头孢曲松钠、大观霉素对淋球菌的最小抑菌浓度 (MIC) ,采用纸片法对菌株作 β 内酰胺酶测定。 [结果 ] 2 3 2株淋球菌中有耐青霉素株 87株 (3 7 5 0 % ) ,环丙沙星高度耐药株 (MIC≥ 16mg/L) 2 5株 (10 77% ) ,没有发现对头孢曲松钠、大观霉素的耐药菌株。 [结论 ]应首选头孢曲松钠或大观霉素治疗淋球菌感染。     

acrAB外排泵对肺炎克雷伯菌耐环丙沙星作用的研究

目的研究临床分离的肺炎克雷伯菌中外排泵基因表达及其对环丙沙星耐药性的影响,明确外排泵在肺炎克雷伯菌对环丙沙星耐药中的作用。方法收集医院2014年9月-2015年2月临床标本中分离的肺炎克雷伯菌36株,采用VITEK-2Compact全自动微生物鉴定仪进行鉴定;K-B纸片扩散法对抗菌药物进行敏感性测定;用PCR方法检测菌株中的外排泵基因;用微量稀释法检测抗菌药物的最低抑菌浓度(MIC)以及泵抑制剂羰基氰氯苯腙(CCCP)存在情况下,肺炎克雷伯菌对环丙沙星MIC值的变化。结果 36株肺炎克雷伯菌中,有16株对环丙沙星耐药,耐药率为44.44%;采用PCR技术对16株耐药菌的外排泵acrAB基因进行检测,其中只有9株耐药菌株的检测结果为阳性,acrAB基因的检出率为56.25%;加入CCCP后,acrAB基因阳性株中,有5株(55.56%)MIC值下降4~16倍,2株(22.22%)MIC值下降两倍,还有2株(22.22%)MIC值未下降。结论 acrAB外排系统是肺炎克雷伯菌耐环丙沙星的一个重要机制,泵抑制剂CCCP可有效抑制acrAB基因的外排作用。     

鲍曼不动杆菌对喹诺酮类耐药机制

目的 探讨鲍曼不动杆菌对氟喹诺酮类药物的耐药机制。方法 采用K-B法检测35株鲍曼不动杆菌对氟喹诺酮类药物的药敏情况。十二烷基磺酸钠一聚丙酰胺凝胶电泳(SDS-PAGE)法检测鲍曼不动杆菌的外膜蛋白(OMP)，直接荧光法检测鲍曼不动杆菌对环丙沙星的吸收和积累，PCR法扩增gyrA基因并对其进行测序。结果 35株鲍曼不动杆菌中有20株对氟喹诺酮类药物耐药，耐药菌株与敏感菌株相比，外膜蛋白在约29Ku条带处消失，在26Ku条带处明显增强。耐药菌株药物积累量不及敏感菌株，经叠氮钠处理后，积累量上升并接近敏感菌株，对PCR扩增产物gyrA测序未发现有突变。结论 鲍曼不动杆菌对氟喹诺酮类药物的耐药与外膜蛋白的低通透性和主动外运有关。     

80株大肠埃希菌靶位基因突变对喹诺酮耐药影响

目的　探讨大肠埃希菌靶位基因突变对喹诺酮类药物耐药的影响。方法　本研究分别用琼脂稀释法和K -B纸片扩散法药敏试验检测了 80株致泌尿系感染的大肠埃希菌环丙沙星MIC的分布和对四种喹诺酮类药物的敏感性 ;PCR扩增大肠埃希菌的gyrA和 parC基因的QRDR区 ,分别对其进行限制性内切酶酶切分析和SSCP分析 ,以检测药物靶位基因可能存在的突变。结果　 80株致泌尿系感染的大肠埃希菌中有 4 7株对环丙沙星耐药 ,耐药率达 5 8.75 % ,2 0株对环丙沙星敏感的菌株 gyrA基因QRDR区未发生改变 ,而 13株敏感株和 4 7株耐药株gyrA 2 4 7bp位点处均存在突变 ,且这 13株对环丙沙星敏感的菌株均对萘啶酸耐药。 33株对环丙沙星敏感的菌株parCSSCP分析 ,均未存在突变。 结论　① 80株致泌尿系感染的大肠埃希菌对环丙沙星的敏感性和对萘啶酸的敏感性存在明显差异 ;②gyrA基因是大肠埃希菌喹诺酮类药物的主要作用靶位。在某些菌株中 ,其 2 4 7位核苷酸位点的改变仅使细菌对环丙沙星的敏感性下降 ,parCQRDR区的突变使细菌的耐药程度增加。     

深圳地区淋球菌耐药性及质粒关系的研究

目的 了解深圳地区淋球菌的营养型分布和4种抗生素的耐药性以及与质粒的关系.方法 对深圳地区113株淋球菌进行最低抑菌浓度测定和产青霉素酶淋球菌检测,同时对其中44例进行质粒分型.结果 113株淋球菌中检出产青霉素酶淋球菌菌株9株(7.96%),质粒介导高度耐四环素菌株16株(14.16%),青霉素耐药菌株73株(64.60%),环丙沙星耐药菌株88株(77.88%),大观霉素、头孢曲松未发现耐药菌株.113株淋球菌分16种营养型,以Pro-、Proto-、Pro-lle、Lle-、Pro-lle Ser 5种营养型为主,占86.73%,其余11种营养型占13.27%.结论 青霉素和环丙沙星的耐药菌株主要分布于Pro-型,质粒介导高度耐四环素菌株主要分布于Lle-型,产青霉素酶淋球菌菌株散在于各种营养型中.     

纸片扩散法常规检测淋球菌药敏试验可靠性研究

目的了解纸片扩散法（K-B法）常规检测淋球菌药敏结果可靠性。方法使用K-B法临床常规检测淋球菌分离株的药物敏感性,采用琼脂稀释法测定上述保存菌株的最低抑菌浓度（MIC）,对两者符合率和敏感性、耐药性进行比较。结果检测72株淋球菌对5种药物的敏感性和MIC,K-B法与琼脂稀释法的符合率分别为青霉素72.2%（52/72）、四环素86.1%（62/72）、环丙沙星59.7%（43/72）、头孢曲松37.5%（27/72）、壮观霉素98.6%（71/72）;两种方法检测菌株对四环素的耐药率均为91.7%,对大观霉素的敏感性差异无统计学意义（P〉0.05）,青霉素K-B法耐药率低于琼脂稀释法,差异有统计学意义（P〈0.05）;环丙沙星K-B法耐药率高于琼脂稀释法,差异有统计学意义（P〈0.01）,头孢曲松K-B法敏感率高于琼脂稀释法,差异有统计学意义（P〈0.01）。结论采用K-B法常规检测淋球菌药物敏感性：（1）大观霉素、四环素符合率高,结果可靠,头孢曲松一致率低,应慎用其结果;（2）K-B法可漏检部分青霉素耐药菌、漏检多数头孢曲松中敏菌株,影响头孢曲松耐药趋势的观察,部分环丙沙星K-B法耐药菌为假阳性;（3）头孢曲松和大观霉素耐药的菌株必须采用琼脂稀释法确证其结果。     

Contribution of AcrAB efflux pump to ciprofloxacin resistance in Klebsiella pneumoniae isolated from burn patients

Resistance to fluoroquinolones has been recently increased among bacterial strains isolated from outpatients. Multidrug-resistant K. pneumoniae is one of the major organisms isolated from burn patients and the AcrAB efflux pump is the principal pump contributing to the intrinsic resistance in K. pneumoniae against multiple antimicrobial agents including ciprofloxacin and other fluoroquinolones. Fifty-two K. pneumoniae isolated from burn patients in Shahid Motahari hospital and confirmed by conventional biochemical tests. Antimicrobial susceptibility testing was done according to CLSI 2011 guidelines, to determine the antimicrobial resistance pattern of isolates. AcrA gene was detected among ciprofloxacin-resistant isolates by PCR assay. MICs to ciprofloxacin were measured with and without carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Forty out of the 52 K. pneumoniae isolated from burn patients in Shahid Motahari hospital were resistant to ciprofloxacin according to breakpoint of CLSI guideline. PCR assay for acrA gene demonstrated that all ciprofloxacin-resistant isolates harbored acrA gene coding the membrane fusion protein AcrA and is a part of AcrAB efflux system. Among these isolates, 19 strains (47.5%) showed 2 to 32 fold reduction in MICs after using CCCP as an efflux pump inhibitor. The other 21 strains (52.5%) showed no disparity in MICs before and after using CCCP. In conclusion, the AcrAB efflux system is one of the principal mechanisms contribute in ciprofloxacin resistance among K. pneumoniae isolates but there are some other mechanisms interfere with ciprofloxacin resistance such as mutation in target proteins of DNA gyrase of topoisomerase IV enzymes.     

Clinical epidemiology of ciprofloxacin resistance and its relationship to broad-spectrum cephalosporin resistance in bloodstream infections caused by Enterobacter species.

OBJECTIVES: To evaluate the clinical features of ciprofloxacin-resistant Enterobacter bacteremia and to examine the risk factors for ciprofloxacin resistance in Enterobacter species isolates causing bacteremia. DESIGN: A case-control study. SETTING: A 1,500-bed, tertiary-care university hospital and referral center. PATIENTS: All patients older than 16 years with Enterobacter species isolated from blood were enrolled. The medical records of 183 patients with clinically significant Enterobacter bacteremia from January 1998 to December 2002 were identified. We compared patients with bacteremia caused by ciprofloxacin-susceptible isolates with patients with bacteremia caused by ciprofloxacin-resistant isolates. RESULTS: Twenty-three (12.6%) of the patients had bacteremia caused by isolates resistant to ciprofloxacin. There were no significant differences in age, gender, underlying diseases, primary site of infection, or Acute Physiology and Chronic Health Evaluation II score between the ciprofloxacin-resistant and the ciprofloxacin-susceptible groups. Broad-spectrum cephalosporin resistance, defined as resistance to cefotaxime or ceftazidime in vitro, was detected in 21 (91.3%) of 23 ciprofloxacin-resistant isolates compared with 65 (40.6%) of 160 ciprofloxacin-susceptible isolates (P < .001). Multivariate analysis revealed that independent risk factors for ciprofloxacin resistance were the prior receipt of fluoroquinolones (P < .001) and broad-spectrum cephalosporin resistance (P < .001). CONCLUSIONS: In Enterobacter species isolates causing bacteremia, ciprofloxacin resistance was closely associated with the prior receipt of fluoroquinolones and broad-spectrum cephalosporin resistance. The close relationship between ciprofloxacin resistance and broad-spectrum cephalosporin resistance is particularly troublesome because it severely restricts the therapeutic options for Enterobacter species infection.     

淋球菌耐环丙沙星与螺旋酶A亚基突变的关系

目的 研究淋球菌对环阿沙星(CIP)耐药与螺旋酶A亚基基因(gyrA)上的喹诺酮耐药决定区(QRDR)突变的关系，方法 PCR扩增gyrA QRDR区，回收扩增片段，再用直接基法进行DNA测序以观察是否存在突变，结果 6株CIP耐药淋球菌的gyrA QRDR区均未发现突变。结论 淋球菌CIP耐药不是由gyrA QRDR突变引起，可能存在其它机制。     

Bacteraemia due to ciprofloxacin-resistant Salmonella enterica serotype Choleraesuis in adult patients at a university hospital in Taiwan, 1996-2004

Eighty-one adult patients with Salmonella enterica serotype Choleraesuis (S. Choleraesuis) bacteraemia treated at a university hospital from 1996 to 2004 were evaluated. Multivariate analysis with a logistic regression model was used to characterize risk factors for primary bacteraemia and mycotic aneurysm and to determine the association of clinical characteristics of patients based on ciprofloxacin susceptibility of the causative organism. The incidence per 100,000 discharges was 0.76 in 1996 and 3.9 in 2004. The overall rate of ciprofloxacin resistance among these isolates was 59% (87 isolates) and the annual rate increased with time from 0% prior to 2000 to 80% in 2004. Among these patients, 48 (59%) had primary bacteraemia and 13 (16%) had secondary bacteraemia with mycotic aneurysm. Seventy (86%) patients had fever at presentation, 22 (27%) developed shock during hospitalization, and eight (10%) died of S. Choleraesuis bacteraemia. Patients with immunocompromised conditions had a higher risk of developing primary bacteraemia (OR 18.442, P < 0.001). Hypertension (OR 15.434, P = 0.002) and male gender (OR 7.422, P = 0.039) were associated with mycotic aneurysm. Patients with mycotic aneurysm were more frequently infected with ciprofloxacin-susceptible isolates (P = 0.028) and ciprofloxacin-susceptible isolates were also more frequently associated with recurrent infection than ciprofloxacin-resistant isolates (P = 0.038). The incidence of S. Choleraesuis bacteraemia has increased in the past 8 years, and this increase is associated with the upsurge of ciprofloxacin-resistant isolates.     

主动外排系统与肺炎克雷伯菌耐药关系研究

目的探讨国内肺炎克雷伯菌对氟喹诺酮类药物耐药与主动外排系统的关系。方法用荧光分光光度法检测氰氯苯腙(CCCP)作用前后细菌对环丙沙星的蓄积,以明确肺炎克雷伯菌耐药与主动外排系统是否有关,分别以聚合酶链反应(PCR)、逆转录-聚合酶链反应(RT-PCR)检测主动外排基因acrA及其表达水平。结果耐药组细菌环丙沙星的聚积浓度明显低于敏感组,CCCP作用后其大幅提高,可达到敏感组的水平,RT-PCR发现耐药组acrA基因表达水平明显高于敏感组。结论国内临床分离的肺炎克雷伯菌对氟喹诺酮的耐药与AcrAB-TolC外排系统有关,其外排作用能被CCCP抑制,为临床提供一种敏感的检测肺炎克雷伯菌主动外排系统的方法。     

鲍氏不动杆菌对喹诺酮类抗菌药物的耐药性分析

目的 分析临床分离的鲍氏不动杆菌对喹诺酮类抗菌药物的耐药特点及耐药机制.方法 采用K-B纸片法测定33株鲍氏不动杆菌对喹诺酮类等21种抗菌药物的耐药性;用PCR技术扩增33株鲍氏不动杆菌的gyrA基因的耐药决定区,PCR产物经纯化后测序与GenBank中的标准序列比较,分析其突变情况.结果 33株鲍氏不动杆菌中,8株对环丙沙星耐药,占24.2％,4株对左氧氟沙星耐药占12.1％;对环丙沙星耐药的8个菌株均有gyrA基因突变,导致氨基酸变异为Ser-83→Leu,其中包括对左氧氟沙星耐药的4个菌株;所有对环丙沙星敏感的菌株未出现gyrA基因突变.结论 gyrA基因突变决定鲍氏不动杆菌对喹诺酮类抗菌药物的耐药.     

鲍曼不动杆菌RND主动外排泵的表达与耐药性的关系

目的检测鲍曼不动杆菌耐药结节分化家族(RND)外排系统的分布,探索其表达与耐药性的关系。方法对南昌大学第一附属医院临床标本分离的59株多重耐药鲍曼不动杆菌进行细菌的鉴定与药敏分析,采用PCR技术检测鲍曼不动杆菌中RND主动外排系统的分布情况,比较不同耐药表型的鲍曼不动杆菌间外排泵基因的表达情况,分析其表达量与耐药的关系,并对RND外排系统的扩增产物进行测序。结果鲍曼不动杆菌对氨苄西林/舒巴坦、亚胺培南、庆大霉素、环丙沙星、左氧氟沙星耐药率高达93.2%、94.9%、88.1%、96.6%、52.5%。59株鲍曼不动杆菌经外排泵及整合子基因PCR扩增检测,adeR、adeS、adeB、adeJ、adeG基因的携带率分别为81.4%、91.5%、93.2%、100.0%、61.0%。不同菌株外排泵基因的表达均不相同,其中庆大霉素、亚胺培南、氨苄西林/舒巴坦耐药组与非耐药组鲍曼不动杆菌adeB、adeJ基因的表达量相比,差异均有统计学意义(均P0.05)。adeABC外排泵的调控基因adeR、adeS的碱基序列未出现基因突变或插入序列。结论 RND外排系统在鲍曼不动杆菌中普遍存在,RND外排系统中adeB、adeJ基因的表达水平升高与细菌对庆大霉素、亚胺培南、氨苄西林/舒巴坦的耐药性有关。     

Risk factors associated with resistance to ciprofloxacin in clinical bacterial isolates from intensive care unit patients.

OBJECTIVE: To determine risk factors and outcomes associated with ciprofloxacin resistance in clinical bacterial isolates from intensive care unit (ICU) patients. DESIGN: Prospective cohort study. SETTING: Twenty-bed medical-surgical ICU in a Canadian tertiary care teaching hospital. PATIENTS: All patients admitted to the ICU with a stay of at least 72 hours between January 1 and December 31, 2003. METHODS: Prospective surveillance to determine patient comorbidities, use of medical devices, nosocomial infections, use of antimicrobials, and outcomes. Characteristics of patients with a ciprofloxacin-resistant gram-negative bacterial organism were compared with characteristics of patients without these pathogens. RESULTS: Ciprofloxacin-resistant organisms were recovered from 20 (6%) of 338 ICU patients, representing 38 (21%) of 178 nonduplicate isolates of gram-negative bacilli. Forty-nine percent of Pseudomonas aeruginosa isolates and 29% of Escherichia coli isolates were resistant to ciprofloxacin. In a multivariate analysis, independent risk factors associated with the recovery of a ciprofloxacin-resistant organism included duration of prior treatment with ciprofloxacin (relative risk [RR], 1.15 per day [95% confidence interval {CI}, 1.08-1.23]; P<.001), duration of prior treatment with levofloxacin (RR, 1.39 per day [95% CI, 1.01-1.91]; P=.04), and length of hospital stay prior to ICU admission (RR, 1.02 per day [95% CI, 1.01-1.03]; P=.005). Neither ICU mortality (15% of patients with a ciprofloxacin-resistant isolate vs 23% of patients with a ciprofloxacin-susceptible isolate; P=.58) nor in-hospital mortality (30% vs 34%; P=.81) were statistically significantly associated with ciprofloxacin resistance. CONCLUSIONS: ICU patients are at risk of developing infections due to ciprofloxacin-resistant organisms. Variables associated with ciprofloxacin resistance include prior use of fluoroquinolones and duration of hospitalization prior to ICU admission. Recognition of these risk factors may influence antibiotic treatment decisions.     

Ciprofloxacin-resistant Salmonella enterica Typhimurium and Choleraesuis from pigs to humans, Taiwan

We evaluated the disk susceptibility data of 671 nontyphoid Salmonella isolates collected from different parts of Taiwan from March 2001 to August 2001 and 1,261 nontyphoid Salmonella isolates from the National Taiwan University Hospital from 1996 to 2001. Overall, ciprofloxacin resistance was found in 2.7% (18/671) of all nontyphoid Salmonella isolates, in 1.4% (5/347) of Salmonella enterica serotype Typhimurium and in 7.5% (8/107) in S. enterica serotype Choleraesuis nationwide. MICs of six newer fluoroquinolones were determined for the following isolates: 37 isolates of ciprofloxacin-resistant (human) S. Typhimurium (N = 26) and Choleraesuis (N = 11), 10 isolates of ciprofloxacin-susceptible (MIC <1 mg/mL) (human) isolates of these two serotypes, and 15 swine isolates from S. Choleraesuis (N = 13) and Typhmurium (N = 2) with reduced susceptibility to ciprofloxacin (MIC >0.12 microg/mL). Sequence analysis of the gryA, gyrB, parC, parE, and acrR genes, ciprofloxacin accumulation, and genotypes generated by pulsed-field gel electrophoresis with three restriction enzymes (SpeI, XbaI, and BlnI) were performed. All 26 S. Typhimurium isolates from humans and pigs belonged to genotype I. For S. Choleraesuis isolates, 91% (10/11) of human isolates and 54% (7/13) of swine isolates belonged to genotype B. These two genotypes isolates from humans all exhibited a high-level of resistance to ciprofloxacin (MIC 16-64 mg/mL). They had two-base substitutions in the gyrA gene at codons 83 (Ser83Phe) and 87 (Asp87Gly or Asp87Asn) and in the parC gene at codon 80 (Ser80Arg, Ser80Ile, or Ser84Lys). Our investigation documented that not only did these two S. enterica isolates have a high prevalence of ciprofloxacin resistance nationwide but also that some closely related ciprofloxacin-resistant strains are disseminated from pigs to humans.     

Fluoroquinolone resistance among Streptococcus pneumoniae in Hong Kong linked to the Spanish 23F clone.

Serotypes 6A/B, 19F, and 23F accounted for 73% of 140 mucosal isolates of Streptococcus pneumoniae from Hong Kong. In pulsed-field gel electrophoresis analysis, a group of related patterns was shared by 14 of 15 ciprofloxacin-resistant and 12 of 16 ciprofloxacin-susceptible isolates. These strains exhibited capsular switching and were highly similar to the Spanish 23F clone.