Effects of subinhibitory concentrations of pefloxacin on the adherence of Staphylococcus aureus to human cells

The adherence of bacterial strains to eukaryotic cells can be influenced by subinhibitory concentrations of antibiotics. The effect of sub- and infra-MICs of pefloxacin, a new broad-spectrum antibacterial quinolone, on the adherence of Staphylococcus aureus to human buccal cells, was studied. Six S. aureus strains belonging to several serotypes and all sensitive to pefloxacin were pretreated with serial twofold dilutions of the drug (from 1/2 to 1/1024 the MIC). After the adhesion test, 100 buccal cells were counted in randomly chosen microscopic fields using a Nomarski interference microscope and attachment was measured as the percentage of cells with at least 50 or more adhering bacteria. Sub-MICs (1/2 and 1/4 the MIC) of pefloxacin increased the diameter of the six staphylococci. All of the strains, grown in the presence of pefloxacin, exhibited a markedly altered capacity for adhesion to buccal cells. The highest significant decrease was observed for 1/2 to 1/8 the MIC, although infra-MICs such as 1/1024 the MIC also decreased the attachment of S. aureus to buccal cells. These results were compared with those obtained with other antibiotics active against S. aureus.     

万古霉素治疗耐甲氧西林金黄色葡萄球菌的疗效和血药浓度分析

目的：探讨万古霉素治疗耐甲氧西林金黄色葡萄球菌感染的临床疗效、血药谷浓度、不良反应三者的关系。方法：调查本院2008年1月-2009年10月住院部确诊为耐甲氧西林金黄色葡萄球菌感染并使用万古霉素治疗者82例,观察其临床疗效、细菌学疗效及不良反应,并测定其血药谷浓度。结果：万古霉素血药谷浓度小于5μg/mL、5～10μg/mL及大于10μg/mL的治疗有效率分别为68.75%、72.73%和81.82%;细菌清除率分别为62.50%、68.18%和72.73%,1例血药谷浓度为14.6μg/mL的患者出现肾毒性。结论：增加万古霉素血药谷浓度可提高治疗耐甲氧西林金黄色葡萄球菌感染的疗效和细菌清除率,但出现肾毒性不良反应几率也相应增大。     

曲伐沙星滴眼液治疗细菌性角膜炎

目的:评价新型氟喹诺酮类抗生素曲伐沙星治疗兔实验性金葡菌性角膜炎的有效性。方法:采用兔角膜基质注射5μL金葡菌(ATCC25923)菌液(含菌100 CFU)的方法建立细菌性角膜炎模型。接种菌9 h后,将炎症发展程度较一致的兔随机分为4组,即接种菌9 h(或16 h)基线组、空白对照组、0.5%左氧氟沙星滴眼液组和0.5%曲伐沙星滴眼液组。按预定给药方案给药,最后一次给药后的1 h对实验兔角膜炎情况进行观察,并进行病理组织观察和房水细菌培养,评价药物治疗细菌性角膜炎的有效性。结果:曲伐沙星和左氧氟沙星对金葡菌(ATCC25923)的MIC分别为0.062 5和0.125 mg·L-1。实验结果表明,相比于空白组,左氧氟沙星组和曲伐沙星组显著降低角膜炎感染的临床症状(P=0.000),而左氧氟沙星组和曲伐沙星则在临床评分方面疗效相当(P=0.766)。菌落计数中,左氧氟沙星组和曲伐沙星组均显著降低角膜菌落数(P=0.000),但曲伐沙星组优于左氧氟沙星组(P=0.001)。结论:曲伐沙星在眼局部给药用于治疗金葡菌性角膜炎方面具有改善临床症状、降低角膜菌落计数的治疗效果。     

Efficacy of ME1036 against meticillin-resistant Staphylococcus aureus and vancomycin-insensitive S. aureus in a model of haematogenous pulmonary infection

ME1036, a novel parenteral carbapenem, was developed for the treatment of meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-intermediate S. aureus (VISA). A model of haematogenous pulmonary infection was induced in mice by tail vein injection of MRSA strain NUMR101 or VISA Mu50 enmeshed in agar beads. After 24h of infection, mice were treated twice daily for 7 days with 200mg/kg/day vancomycin (VCM) or ME1036. Mice infected with VISA were also pre-treated with cyclophosphamide to induce an immunocompromised state. The number of viable bacteria in the lungs was counted 12h after the final drug treatment. VCM decreased the number of viable MRSA in the lungs in comparison with the control, although the difference was not significant (mean+/-standard error of the mean log(10) colony-forming units (CFU)/lung=6.876+/-0.54 vs. 8.25+/-0.41, respectively). In contrast, treatment with ME1036 resulted in a significant decrease in the number of viable MRSA (log(10)CFU/lung=2.69+/-0.44 (n=6); P<0.0001) compared with both the VCM-treated and control mice. In the VISA-infected mice, ME1036 significantly reduced the number of viable bacteria compared with VCM and control (log(10)CFU/lung=3.65+/-0.68 for ME1036 vs. 5.71+/-0.75 for VCM (P<0.05) and 7.07+/-0.45 for control (P<0.001)). ME1036 produced >3 log(10) reduction versus control against both MRSA strains (>5 log for the VCM-susceptible strain and 3.4 log for the VISA), whereas VCM produced <1.3 log for both strains.     

耐药葡萄球菌及其感染的治疗

葡萄球菌为革兰阳性球菌，多数为非致病菌，少数可导致疾病。除金黄色葡萄球菌(金葡菌)产生血浆凝固酶外，其它菌种凝固酶皆属阴性，称为凝固酶阴性葡萄球菌(CNS)，其中较常见的致病菌为表皮葡萄球菌(表葡菌)、溶血葡萄球菌和腐生葡萄球菌(腐葡菌)。     

Antimicrobial therapy of Staphylococcus aureus bloodstream infection

Staphylococcus aureus bloodstream infection (BSI) contributes significantly to the morbidity and mortality of in-patients. The optimal therapy for methicillin-susceptible S. aureus BSI consists of penicillins. The efficacy of these drugs is well documented from several published data and supported from a long clinical experience. Methicillin-resistant S. aureus (MRSA) strains are responsible for the majority of nosocomial BSI and are recovered with increasing frequency at hospital admission. Although glycopeptides still represent the drugs of choice, there are several concerns on the treatment of MRSA BSI: reports of clinical failure with vancomycin treatment, regardless of the in vitro susceptibility; increasing reports of MRSA strains with reduced vancomycin susceptibility; difficulty in therapeutic dosage monitoring of teicoplanin; lack of evidence on the efficacy of combination therapy. Recently, new drugs have been introduced in the therapeutic arsenal for MRSA infections, but their clinical use is not yet clearly established for BSI. The review summarises evidence on present therapeutic options for the treatment of S. aureus BSI.     

Antimicrobial therapy of Staphylococcus aureus bloodstream infection

Staphylococcus aureus bloodstream infection (BSI) contributes significantly to the morbidity and mortality of in-patients. The optimal therapy for methicillin-susceptible S. aureus BSI consists of penicillins. The efficacy of these drugs is well documented from several published data and supported from a long clinical experience. Methicillin-resistant S. aureus (MRSA) strains are responsible for the majority of nosocomial BSI and are recovered with increasing frequency at hospital admission. Although glycopeptides still represent the drugs of choice, there are several concerns on the treatment of MRSA BSI: reports of clinical failure with vancomycin treatment, regardless of the in vitro susceptibility; increasing reports of MRSA strains with reduced vancomycin susceptibility; difficulty in therapeutic dosage monitoring of teicoplanin; lack of evidence on the efficacy of combination therapy. Recently, new drugs have been introduced in the therapeutic arsenal for MRSA infections, but their clinical use is not yet clearly established for BSI. The review summarises evidence on present therapeutic options for the treatment of S. aureus BSI.     

Imported methicillin-resistant Staphylococcus aureus infection: a case report.

The first isolate of a methicillin-resistant strain of Staphylococcus aureus at the Wellington Hospital was made on 31 March 1976, from a man who had emigrated from the United Kingdom in 1973. The infection was successfully treated with co-trimoxazole and fucidin. The epidemiological implications of this infection are discussed.     

Antimicrobial therapy of methicillin resistant Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) is now one of the commonest causes of nosocomial infection worldwide. The mainstay of treatment until now has been the glycopeptides (vancomycin and teicoplanin). They are not without toxicity and need parenteral administration and monitoring of levels. The increasing frequency of MRSA infections, coupled with the emergence of glycopeptide resistance in S. aureus has made the introduction of new drugs active against Gram-positive organisms essential. New agents active against Gram-positive organisms represent either genuinely novel classes of antimicrobials (e.g., oxazolidinones and lipoproteins) or those derived from existing classes (e.g., tetracyclines, glycopeptides, streptogramins and cephalosporins). Some of these newer antibiotics appear to be effective against multi-resistant organisms including MRSA.     

Methicillin-resistant Staphylococcus aureus infection of percutaneous endoscopic gastrostomy sites

BACKGROUND: Antibiotic prophylaxis for percutaneous endoscopic gastrostomy insertion remains controversial. The bacteriology of peristomal infection following percutaneous endoscopic gastrostomy insertion has been poorly studied, leading to uncertainty regarding the optimum choice of antibiotic for prophylaxis. AIM: To investigate the bacteriology of peristomal infection following percutaneous endoscopic gastrostomy insertion and to determine the contribution of methicillin-resistant Staphylococcus aureus. METHODS: Nasal and pharyngeal swabs were taken from a consecutive series of patients prior to percutaneous endoscopic gastrostomy insertion over a 6-month period. Bacterial colonization and infection at the peristomal site were prospectively evaluated at days 2/3 and 7 post-insertion. RESULTS: Thirty-one patients underwent percutaneous endoscopic gastrostomy insertion (mean age, 68 years; cerebrovascular disease, 52%). Naso-pharyngeal colonization by methicillin-resistant Staphylococcus aureus (35%) invariably led to peristomal colonization following percutaneous endoscopic gastrostomy insertion. Peristomal infection occurred in eight (26%) cases (seven (88%) methicillin-resistant Staphylococcus aureus- positive). Peristomal infection was significantly more likely to occur in patients with naso-pharyngeal methicillin-resistant Staphylococcus aureus colonization (odds ratio, 10.8; 95% confidence interval, 1.6-70.9). CONCLUSIONS: Naso-pharyngeal methicillin-resistant Staphylococcus aureus colonization invariably predicts peristomal methicillin-resistant Staphylococcus aureus colonization following percutaneous endoscopic gastrostomy insertion, and is associated with an increased peristomal infection rate. Currently recommended antibiotic prophylaxis regimens may be inappropriate in institutions with significant methicillin-resistant Staphylococcus aureus colonization rates.     

Activity of combinations of ceftazidime, imipenem and pefloxacin against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa

The chequerboard technique was used to look for synergistic combinations of ceftazidime, imipenem and pefloxacin. The synergistic combinations were used in vivo in mice experimentally infected with Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa. In vitro ceftazidime/imipenem, ceftazidime/pefloxacin and pefloxacin/imipenem combinations showed synergistic effects against Staphylococcus aureus and S. typhimurium and additive effects against P. aeruginosa. Only the ceftazidime/pefloxacin combination was synergistic against E. coli while the ceftazidime/imipenem and pefloxacin/imipenem combinations resulted in additive effects. In vivo, combination of ceftazidime/imipenem against E. coli infection and the pefloxacin/imipenem combination against S. typhimurium infection were protective.     

Outbreak of methicillin-resistant Staphylococcus aureus infection in a New Zealand hospital

During a 17 month period from March 1985 to July 1986, 30 patients and four members of staff became infected or colonised with a single strain of methicillin-resistant Staphylococcus aureus (MRSA) during an outbreak which originated at Wellington Hospital. Initially, crossinfection occurred within the intensive care unit but infected or colonised patients became distributed to 14 hospital wards and to five other hospitals within New Zealand. MRSA septicaemia contributed to the death of two patients. The source of the epidemic strain of MRSA has not been established with certainty, but may have been introduced by a staff nurse known to be a carrier when employed at an Australian hospital. The investigation, management and eventual control of this first outbreak in New Zealand are described.     

侵袭性甲氧西林敏感金黄色葡萄球菌感染因素及耐药分析

目的 回顾性分析通过无菌体液标本培养确诊的甲氧西林敏感金黄色葡萄球菌(MSSA)感染病例的临床分布特点、感染危险因素及不同感染途径耐药率，为管控院内感染提供依据。方法 共纳入通过无菌体液培养确诊的MSSA感染且病例资料完整的80例患者为病例组，以同期感染甲氧西林耐药金黄色葡萄球菌(MRSA)的患者70例作为对照组，细菌培养和鉴定采用法国梅里埃VITEK2-COMPACT全自动细菌鉴定及药敏分析系统，收集患者临床资料，包括住院时间、感染季节、基础疾病及诊疗信息等，危险因素单因素分析分别采用了Person卡方检验，多因素分析使用非条件Logistic回归模型。结果 住院时间、感染季节、多器官衰竭、烧伤、白细胞低下、糖尿病、皮肤组织感染、术后伤口感染、肾功能衰竭、低蛋白血症、恶性肿瘤、肝硬化、白血病及骨髓增生异常综合征(MDS)、感染前使用糖皮质激素和留置静脉导管是MSSA感染的单因素危险因素(P<0.05);夏季感染(OR=14.040,P=0.002)、秋季感染(OR=8.673,P=0.003)、烧伤(OR=16.125,P=0.001)、糖尿病(OR=4.321,P=0.029)、术后伤口感染(OR=5.602,P=0.010)、恶性肿瘤(OR=12.968,P=0.034)、感染前使用糖皮质激素(OR=4.422,P=0.031)、留置静脉导管(OR=0.243,P=0.049)和住院时间(OR=0.037,P=0.000)是MSSA感染的独立危险因素。MSSA对万古霉素、利奈唑胺、替考拉宁、替加环素、奎奴普丁/达福普汀、利福平和苯唑西林的耐药率为0%。血流、尿液、浆膜腔积液感染MSSA对四环素、莫西沙星、左氧氟沙星、庆大霉素和复方新诺明的耐药率均较低，对克林霉素和红霉素的耐药率均大于60.0%;对青霉素的耐药率均大于90.0%。结论 住院时间、感染季节、多器官衰竭、烧伤、白细胞低下、糖尿病、皮肤组织感染、术后伤口感染、肾衰、低蛋白血症、恶性肿瘤、肝硬化、白血病及MDS、感染前使用糖皮质激素和留置静脉导管是MSSA感染的单因素危险因素；住院时间、夏秋季感染、烧伤、糖尿病、术后伤口感染、恶性肿瘤、感染前使用糖皮质激素和留置静脉导管是MSSA感染的独立危险因素。MSSA对抗菌药物均较敏感，血流感染MSSA耐药率低于其他途径。     

耐甲氧西林金黄色葡萄球菌感染情况调查及药敏分析

目的利用药敏试验,对耐甲氧西林表皮葡萄球菌(MRSA)感染情况进行调查分析,研究其耐药性,探究抗生素的合理应用。方法 2014年2月至2015年2月在我院分离出MRSA的86例患者进行回顾性分析,经细菌鉴定后得出40株MRSA,作为观察组;46株耐甲氧西林敏感型表皮葡萄球菌(MSSA),作为对照组。结果观察组MRSA在新生儿科、重症监护室的检出率明显少于对照组MSSA的检出率(P<0.05),而观察组在外科、内科、骨科的检出率明显高于对照组的检出率,尽管2组在内科和骨科检出率的比较无明显差别,但2组在新生儿科、重症监护室、外科的检出率差异有统计学意义(P<0.05)。观察组对青霉素、头孢西丁、红霉素、阿奇霉素的耐药率明显高于对照组的耐药率(P<0.05),而对于万古霉素和庆大霉素,2组耐药率虽差异有统计学意义(P<0.05),但耐药率相对青霉素、头孢西丁、红霉素、阿奇霉素已大大下降,甚至为0。结论 MRSA感染多发生在新生儿科,其次是重症监护室和外科,MRSA比MSSA耐药更明显。     

Influence of ticlopidine on the development of experimental Staphylococcus aureus endocarditis

Previously, we have shown that aspirin administration reduces the bacterial density and weight of aortic vegetations in a rabbit model of Staphylococcus aureus endocarditis. In the present paper, we sought to determine if ticlopidine, another potent inhibitor of platelet aggregation, also influences the development of endocarditis. Animals received either no ticlopidine (control), or oral doses of 10, 50, and 100 mg/kg daily. The 10 and 100 mg/kg treated groups had a statistically significant reduction of the vegetative weight as compared with the untreated controls. Although the 50 mg/kg dose did not result in a statistically significant difference (P = 0.058) in weight when compared with control, this dose also produced a substantial reduction in aortic value vegetation weights. None of the ticlopidine doses tested significantly altered the bacterial density relative to untreated controls. These findings suggest that ticlopidine alters the development of cardiac vegetations and may be useful agent for the prevention and/or treatment of infective endocarditis.     

Chemotherapy of experimental leptospiral infection in mice

A strain of Leptospira zanoni was used to produce chronic renal infections in young white mice. A variant of this strain produced an acute disease with over 50% mortality. The responses of both forms of disease to chemotherapy were studied. When treatment of the acute disease was initiated before jaundice occurred, suitable single doses of streptomycin, chlortetracycline, tetracycline, erythromycin, oxytetracycline and oxytetracycline (in oil) prevented death and chronic renal infection in a high percentage of mice. Bicillin, a long-acting penicillin preparation, was more effective than other penicillins, but it prevented the development of chronic renal infection in only half the treated mice. Streptomycin was the only antibiotic of which a single administration regularly cured the chronic renal infections: chlortetracycline, tetracycline and oxytetracycline (in oil) were partially effective. Oxytetracycline, chloramphenicol, Bicillin, fortified penicillin, procaine penicillin and potassium penicillin had no permanent action. The suitability of mice as laboratory animals in the study of experimental leptospirosis and the need for complete cure of carriers of chronic renal infection are emphasized. The above findings indicate that streptomycin is the drug of choice for the treatment of leptospirosis in animals, and that it is worthy of further trial in man.