Changes in sensitivity of clinical strains of bacteria to dioxidine from 1984 to 1988

Dioxidine sensitivity of 7291 strains of aerobic bacteria and 163 strains of anaerobic bacteria was assayed with the disk diffusion method. The sensitivity of the aerobes was studied in the time course from 1984 to 1988. It was shown that during the 5-year period, the sensitivity of gram-positive bacteria to dioxidine gradually decreased. At the same time no increase in resistance of gram-negative organisms to dioxidine was observed. A high dioxidine sensitivity of obligate anaerobes, i.e. Clostridium spp., Bacteroides spp., Fusobacterium spp., anaerobic cocci and others was demonstrated.     

Distribution of phage-resistant Pseudomonas aeruginosa strains

The sensitivity of a number of P. aeruginosa clinical strains to virulent bacteriophages has been studied. Phage-resistant strains have been found to constitute a considerable proportion among the tested P. aeruginosa strains. The strains under study fall into 19 groups differing in their sensitivity to the bacteriophages used in this investigation. The strains belonging to some groups are phenotypically identical to experimentally obtained P. aeruginosa phage-resistant mutants PAO. The use of bacteriophage mutants has made it possible to demonstrate that in most cases the resistance of P. aeruginosa natural strains to type phi k phages is due to disturbances in their adsorption, whereas their resistance to type phi m and phi mn phages is, seemingly, not linked with disturbances in their capacity for adsorption on the cell membranes of the bacteria.     

In vitro effect of subinhibitory concentrations of ceftazidime and meropenem on the serum sensitivity of Pseudomonas aeruginosa strains

The aim of this study was to determine the effect of subminimal inhibitory concentrations (subMICs) of ceftazidime, meropenem and gentamicin on the in vitro serum sensitivity of Pseudomonas aeruginosa strains isolated from a variety of isolation sites at two medical wards and an intensive care unit in a government university hospital in Croatia. A total of 20 serum-resistant P aeruginosa strains isolated from different clinical specimens were selected. Bacteria were exposed to 1/2, 1/4, 1/8, 1/16, and 1/32 x MIC of each antibiotic tested. Sensitivity of P. aeruginosa strains to bactericidal activity of normal human serum before and after bacterial exposure to subMICs was determined. Significant difference in serum sensitivity of the strains was observed after the bacteria were exposed to subMICs of ceftazidime and meropenem (p < 0.01), while the exposure to subMICs of gentamicin did not affect significantly the resistance of tested strains to the serum bactericidal activity. Comparing the number of serum-resistant strains before and after exposure to subMICs of antibiotics, statistically significant differences were determined (p < 0.01) after exposure of the strains to 1/2, 1/4, 1/8 and 1/16 x MIC of meropenem, and after exposure to 1/2, 1/4 and 1/8 x MIC of ceftazidime. SubMICs of ceftazidime and meropenem affected not only the resistance to serum bactericidal activity of bacteria, but also their morphology. The alterations in bacterial morphology caused by subMICs of ceftazidime and meropenem could be connected with consecutive bacterial serum sensitivity.     

Antiseptic resistance of clinical strains of Staphylococcus aureus

To evaluate the activity of antiseptics and the sensitivity-resistance of bacteria to antiseptics, a number of characteristics has been used, including the minimum inhibiting concentration for different strains, the frequency of statistical and clinical resistance, the antiseptic activity index. A wide spread of S. aureus strains isolated from patients with hospital infections has been revealed. Differences in the resistance of bacterial strains have been established, depending on the type of the antiseptic and the ecovar of bacteria: among hospital ecovars, resistant strains occur more frequently and can resist a wider range of antibiotics. In staphylococcal hospital ecovars the occurrence and level of resistance to a number of widely used antiseptics increase with time. In connection with a wide spread of staphylococcal hospital strains resistant to antiseptics, measures on the control of the circulation of such strains should be introduced into hospitals, and the data thus obtained should be used for the periodic reevaluation of antiseptics used in medical practice and for the choice of preparations to be used for individual therapeutic and prophylactic antisepsis.     

Experimental criteria for interpretation of bacterial sensitivity to dioxidine determined by diffusion from the disks

Antibacterial activity of dioxidine against aerobic and facultative anaerobic organisms under conditions of anaerobiosis i. e. conditions really observed for example in abscess cavities or necrotic tissues is 30 to 100 times as high as that under aerobic conditions. There is a relationship between sensitivity of bacteria to dioxidine under aerobic and anaerobic conditions which is expressed by the regression equation. Therefore, comparison of the MICs determined under anaerobic conditions with the growth inhibition zones formed by disks with the drug under aerobic conditions is possible. The MIC of dioxidine was determined under anaerobic conditions for 179 clinical strains of aerobic and facultative anaerobic bacteria and the growth inhibition zones of the same bacteria under aerobic conditions were evaluated with the use of disks containing 100, 75, 50, 25, 20, and 15 micrograms of the drug. The border line. MIC differentiating between resistant and sensitive strains was chosen to be equal to 4 micrograms/ml. Differentiation of the strains into sensitive and resistant ones by the values of the growth inhibition zones was performed with the method of error minimization described by C. Metzler and R. De Haan in 1974. Disks containing 25 micrograms of the drug allowed one to differentiate the strains under aerobic conditions into sensitive and resistant ones: the growth inhibition zones greater than 11 mm corresponded to the sensitive strains (the MIC smaller than 4 micrograms/ml) and the growth inhibition zones smaller than 11 mm corresponded to the resistant strains (the MIC greater than 4 micrograms/ml).     

伤口感染病原菌分布及耐药谱分析

目的探讨创伤患者伤口感染的常见病原菌及其耐药性,指导临床合理用药。方法回顾分析2010年至2012年创伤患者感染伤口分泌物的细菌分离培养及体外药物敏感试验,对感染的主要病原菌及耐药性进行分析。结果分离到细菌1086株,居于感染首位的是金黄色葡萄球菌（23．6％）,其次是大肠埃希菌（23．2％）,肺炎克雷伯菌（10．2％）,鲍曼不动杆菌（8．8％）,铜绿假单胞菌（6．6％）,分离到8株白色假丝酵母菌（0．7％）;耐甲氧西林金黄色葡萄球菌（metieillin—multiple resistance S．attrelts,MRSA）检出率为71．5％,MRSA除对万古霉素、利奈唑胺100％敏感外,对其他常用抗菌药物均存在较高的耐药性,与MRSA的耐药性明显高于MSSA（P〈0．01）。产超广谱B一内酰胺酶菌株（extended—spectrumbeta—lactamase,ESBLs）的检出率为64．5％,除碳青霉烯类抗菌药物外,ESBLs对喹诺酮类、氨基糖甙类等的常用抗菌药物存在较高的耐药率;其耐药率远高于非ESBLs（P〈0．01）;多重耐药的铜绿假单胞菌（multi—drug resistant Pesudomonas aeruginosa,MDRPA）检出率为40．3％（29／72）,耐碳青霉烯的鲍曼不动杆菌（Carbapenems—resistant Acineto—bacterbaumannii,CA—Ab）的检出率为43．2％（41／95）。仅头孢哌酮／舒巴坦及阿米卡星有良好的敏感性（〉50％）,而对其余绝大部分常用抗菌药物的耐药性相当严重。结论伤口感染以革兰阳性球菌为主,感染病原菌多为多重／泛耐药菌株,对常用抗菌药物甚至碳青霉烯类耐药性严重,应该引起高度重视,临床应据细菌药物敏感性试验报告选用抗菌药物。     

Effect of tannin extract against Pseudomonas aeruginosa producing metallo beta-lactamase

Carbapenems are the most potent beta-lactam agents with a broad-spectrum activity against Gram-negative and Gram-positive bacteria. They are stable in the presence of penicillinases and cephalosporinases. This study was focused on frequency of metallo beta- lactamase (MBL) among Pesudomonas aeruginosa strains isolated in patients with urinary tract infection, effect of tannin against PA positive strains which produced blaVIM or blaIMP and both of these genes (Species). Detection of MBL was performed by phonotypic and genotypic methods. Tannin extract was tested against P. aeruginosa producing MBL. During the study period, 240 P. aeruginosa isolates were identified. Among them 64 (26.6 percent) isolates were imipenem non-susceptible and confirmed by imipenem/EDTA. Our results revealed that the growth of blaVIM positive P. aeruginosa inhibited at 15 microg/ml concentration. The experiment repeated for blaIMP-positive P. aeruginosa and P. aeruginosa which harbored blaIMP and blaVIM, the results showed 35 microg/ml was the best concentration for inhibition of P. aeruginosa-positive blaIMP and also P. aeruginosa blaIMP and blaVIM. In conclusion, tannin was effective against P. aeruginosa producing blaVIM and blaIMP and both of them so it can be substituted with common antibiotics. The result showed significantly P. aeruginosa-harbored blaIMP was more responsible for imipenem resistance than P. aeruginosa-positive blaVIM. Interestingly, tannin was more effective against MBL-P. aeruginosa in comparison with current antibiotics.     

An evaluation of the suitability of the European suspension test to reflect in vitro activity of antiseptics against clinically significant organisms

The effectiveness of four antiseptics representing soluble phenolics (Dettol), Quaternary Ammonium Compounds (QAC) (Dettol Hospital Concentrate: DHC), mixed QAC/chlorhexidine (Hibicet Hospital Concentrate: HHC) and povidone iodine (Betadine) was assessed using the proposed phase 2 step 1 European Suspension test. The in vitro activity of the antiseptics against two of the proposed challenge strains, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, was compared with that of 14 problematic clinical isolates of bacteria from a range of genera, including some multiple antibiotic resistant strains, and a clinical isolate of Candida albicans. In addition to the 5 min contact time recommended in the European test, a 1 min time was included. All four products, at their recommended use dilutions and a contact time of 5 min, achieved a Microbicidal Effect (ME) log reduction of at least 5 against the majority of organisms. Differences in activity between products were more pronounced and therefore the tests more discriminatory, when the contact time was reduced to 1 min. The clinical strains were not overtly more resistant to antiseptics than the standard test strains, suggesting that the CEN test strains mimic the antiseptic susceptibility of clinical isolates.     

Drug susceptibility of Pseudomonas aeruginosa strains isolated from patients of a hospital and specialistic outpatients clinics of the SP ZOZ in Nidzica

The aim of this study was to evaluate a frequency of isolation and antimicrobial susceptibility testing (AST) of Pseudomonas aeruginosa strains cultured from clinical specimens collected from patients hospitalized in wards and specialistic outpatients clinics of a hospital in Nidzica (01. 09. 2000 -31. 12. 2003). During over three years 392 Pseudomonas aeruginosa strains were cultured from 16346 clinical samples provided to bacteriological laboratory. P. aeruginosa strains were isolated from 2.5% of examined specimens. Susceptibility of Pseudomonas aeruginosa strains to antimicrobial agents was tested. The highest in vitro activity against clinical P. aeruginosa strains demonstrated imipenem. One strain was resistant to imipenem. This strain was isolated from a patient of a surgical department. Metalo-beta-lactamase was not detected (MBL-negative strain).Twenty nine strains were ESBL producer (7.4% of all strains). The contribution of Pseudomonas aeruginosa strains to the etiology of nosoconial and ambulatory infections increases. In vitro activity of antibacterial agents against P. aeruginosa strains should be monitored during therapy of infections. Resistance to antibiotics/chemothe-rapeutics may be acquired during treatment with antibacterial agent to which P. aeruginosa strain was susceptible according to the antibiogram.     

Antibiotic resistance in clinical strains of Pseudomonas aeruginosa isolated from 1979-1984

The levels and spectra of drug resistance were determined in 530 strains of P. aeruginosa isolated in hospitals of three cities of the USSR within 1979-1984. Their conjugative R plasmids were searched for and distribution of various type resistance determinants in the composition of these plasmids was investigated. The results were compared with the findings of analogous studies on clinical strains of P. aeruginosa isolated within 1976-1979. It was shown that there were a rise in the relative number of the strains resistant to kanamycin and a decrease in the occurrence of the P. aeruginosa strains resistant to streptomycin, tetracycline and sulfanilamides. The frequency of the kanamycin, carbenicillin and gentamicin resistance genes in the composition of the detected conjugative R plasmids increased. Hybridization of 32P-labeled probes containing various type antibiotic resistance determinants with strains of P. aeruginosa ML (PAO) containing conjugative R plasmids was indicative of wide spread of genes determining APH(3')II and APH(3") and determinants of classes A and C in the composition of the studied plasmids.     

无多重耐药危险医院获得性肺炎病原菌分布特点与耐药性分析

目的分析温州医科大学附属义乌医院无多重耐药危险医院获得性肺炎（HAP）病原菌分布特点及耐药性。方法人选无多药耐药危险因素的医院获得性肺炎（HAP）患者352例,按照发病时间分为早发HAP组与晚发HAP组,采集合格痰标本,进行细菌分离、鉴定和药敏试验,并分析比较患者病原菌分布特点及耐药性。结果人选的352例患者共分离m393株病原菌,HAP最常见的病原菌排名前五位的分别是为肺炎克雷伯杆菌、大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌及鲍曼不动杆菌,早发HAP排名前五位的分别是肺炎克雷伯杆菌、大肠埃希菌、金黄色葡萄球菌、肺炎链球菌和铜绿假单胞菌,晚发HAP排名前五位的分别是肺炎克雷伯杆菌、大肠埃希菌、铜绿假单胞菌、鲍曼不动杆菌和金黄色葡萄球菌,两组患者革兰阳性菌与革兰阴性菌所占比例差异无统计学意义（P〉0．05）,78株革兰阳性菌对常用抗生素的耐药率早发与晚发HAP差异无统计学意义（P〉0．05）,296株革兰阴性菌对常用抗生素的耐药率,早发HAP与晚发HAP除了对哌拉西林和阿莫西林克拉维酸钾的耐药率差异有统计学意义（P〈0．05）,其余的差异有统计学意义（P〉0．05）,但是晚发HAP中检出耐甲氧西林金葡菌（MRSA）、产ESBLs肺炎克雷伯杆菌及耐碳青霉烯鲍曼不动杆菌（CR—AB）比例增高。结论无多重耐药危险因素的医院获得性肺炎（HAP）患者,早发与晚发HAP感染病原菌差别不大,虽晚发HAP的耐药率相对较高,但对大部分抗菌素敏感,所以适当使用抗菌素,对于减轻选择抗菌药物的压力、减少耐药菌株的产生和二重感染有重要意义。     

肺结核合并非发酵菌下呼吸道感染的临床特征及耐药性分析

目的了解肺结核患者合并非发酵菌下呼吸道感染的临床特征及耐药性,为临床合理使用抗菌药物提供依据。方法采用ATB全自动细菌鉴定仪,对临床分离菌株进行菌种鉴定,用K．B法对非发酵菌做药物敏感试验。结果从肺结核患者下呼吸道标本中共分离非发酵菌156株,其中铜绿假单胞菌最多,占46．5％,其次为鲍曼不动杆菌和嗜麦芽寡养单胞菌,分别占37．8％和9．6％。药敏试验显示5种非发酵菌对多种抗生素均表现为高度耐药或多重耐药,高于相关研究,差异有统计学意义（P≤0．05）。结论肺结核患者肺部感染非发酵菌的分离率较高,多重耐药现象严重,临床应重视非发酵菌感染和耐药性监测。     

Genetic transfer of Pseudomonas aeruginosa R factors to plant pathogenic Erwinia species.

The R factors RP1, R68 and R91 were freely transmissible to and from Pseudomonas aeruginosa, Salmonella typhimurium, and various plant pathogenic Erwinia spp. The antibiotic resistance spectrum of R+ Erwinia recipients was similar to those of other bacteria harboring these R factors, but maximum resistance levels differed with each recipient. The sponstaneous elimination of these factors from the Erwinia strains and the ability to transfer multiple antibiotic resistance suggest that these exist as plasmids in these hosts. Several, but not all, RP1-carrying Erwinia strains were sensitive to the RP1 specific phage PRR1. The R factor R18-1 was also transferred from P. aeruginosa to Erwinia spp. R18-1 was unstable in all Erwinia strains. Stable strains were isolated in which R18-1 could not be eliminated by sodium dodecyl sulfate and could not be transferred to other strains.     

Antipseudomonal Activity of α-Sulfoaminopenicillins

A series of penicillins characterized by the presence of a sulfoamino or a modified sulfoamino group in the side chain was subjected to in vitro antimicrobial screening tests. Although the most potent members of the series were less active than benzylpenicillin against gram-positive bacteria and comparably active against most gram-negative bacteria, they were, on the average, 8 to 16 times more effective against strains of Pseudomonas aeruginosa. In other comparative laboratory tests against P. aeruginosa, these compounds were about as active as carbenicillin and four to eight times more active than ampicillin. An examination of structure-activity relationships indicated that maximal potency was obtained with penicillins having an alpha-(aromatic or heteroaromatic)-alpha-sulfoaminoacetamido side chain. The compound with an alpha-phenyl group was comparable in activity to those having an alpha-(2- or 3-thienyl) group, whereas any modification in position or structure of the alpha-sulfoamino group reduced activity. Results of studies with a cell-free P. aeruginosa beta-lactamase suggest that the marked inhibitory effects of alpha-sulfoamino penicillins for P. aeruginosa can be attributed, at least in part, to their high degree of resistance to this enzyme. Some derivatives, however, had weak antipseudomonal activity, despite possessing a high degree of beta-lactamase resistance.     

Conservation of components of the Escherichia coli export machinery in prokaryotes

Esterase electrophoretic typing was used to classify clinical isolates of Pseudomonas aeruginosa. One hundred and twenty-seven P. aeruginosa strains belonging to 16 serotypes (including 16 non-typeable strains) and isolated from diverse human infections in three hospitals, and the type strain ATCC 10 145, were tested. Four main kinds of esterase and 4 additional esterases were distinguished by their spectra of hydrolytic activity toward synthetic substrates and by their sensitivity or resistance to di-isopropyl fluorophosphate. The electrophoretic variations of these enzymes were used to define 42 zymotypes. Electrophoretic typing of esterase appeared to be more sensitive than serotyping and the results of the two methods did not correlate. When the two typing methods were used in parallel, 78 different combinations of serotype and zymotype were obtained.     

A comparative analysis of the antibacterial activity of antiseptics and antibiotics on samples of Pseudomonas aeruginosa

Antibiotic and antiseptic preparations, currently used in medical practice, have been tested on the same P. aeruginosa samples and compared by the amplitude of their minimal inhibiting concentration (MIC) values, determined as the average MIC values for the samples under test, by the proportion of variants resistant to the tested preparations, by the distribution of strains in the resistance spectrum, and by the pace of the increase of resistant variants under natural conditions in 5-10 years. On the basis of the results obtained in this study a conclusion has been made that in some cases of local application antiseptic preparations have advantages over antibiotics, especially in controlling hospital strains of microorganisms. The authors believe that the heterogeneity of microbial populations, as well as the frequency of the appearance of resistant variants and the activity of the mechanisms of their selection in hospitals, is of great importance in the development of new preparations, in the re-evaluation of currently used preparations and in the choice of the optimum preparation in concrete situations.     

Frequency and susceptibility patterns of non-fermenting gram-negative rods isolated from patients hospitalised in intensive care units of a tertiary care hospital

The aim of the study was to assess frequency and susceptibility to antimicrobial agents of non-fermenting gram-negative rods isolated from clinical specimens obtained from patients requiring intensive care, with emphasis on profile of the unit. Identification of cultured isolates was done using automated VITEK and API systems (bioMerieux, France). Susceptibility to antimicrobial agents was tested by a disk-diffusion method according to the NCCLS recommendations. In total the analysis comprised 425 strains of non-fermenting gram-negative rods, constituting 58.9% of all isolates of gram-negative bacteria. In blood cultures predominated strains of A. baumannii (46.8%) and P. aeruginosa (40.4%), while in cultures of other clinical specimens these bacteria comprised 42.9% and 43.9% of isolates. Major differences were observed in frequency of these species on both ICU units. Strains of non-fermenting rods isolated from blood cultures comprised a lower percentage of strains susceptible to antimicrobials (particularly cefepime and carbapenems) than isolates cultured from other specimens. Strains of A. baumannii resistant to imipenem and meropenem were detected with a frequency of 12.5% and 26.7%, respectively. Resistance of P. aeruginosa strains to carbapenems was 62.2% and 44.3%, respectively. There was a relatively high percentage of strains susceptible to cefepime (82.0%), ceftazidime (78.9%), amikacin (77.8%) and piperacillin/tazobactam (69.7%). Conclusions: 1. There was a predominance (58.9%) of strains of gram-negative non-fermenting rods. 2. Isolates from blood cultures were characterised by a much higher percentage of resistant strains in comparison to other specimens. 3. Strains of A. baumannii resistant to carbapenems were recorded. 4. There were differences in frequency and antimicrobial susceptibility among the strains of P. aeruginosa and A. baumannii depending on the type of clinical specimen and ICU profile.     

2004～2010年武汉同济医院临床分离多重耐药菌株监测分析

目的了解武汉同济医院2004年至2010年临床分离多重耐药菌株的检出情况。方法对临床分离菌株,采用纸片扩散法按统一的方案进行药敏试验。按照CLSI 2009年标准进行判断。结果 2004年至2010年该院耐甲氧西林金葡菌（MRSA）和耐甲氧西林凝固酶阴性葡萄球菌（MRSCN）的检出率分别在35.6%～63.8%和21.5%～61.4%。2004年至2010年共检出36株耐万古霉素肠球菌（VRE）。大肠埃希菌产ESBLs株检出率在29.6%～81.7%,肺炎克雷伯菌产ESBLs株检出率在36.0%～56.6%,产酸克雷伯产ESBLs株检出率在35.3%～67.4%,奇异变形杆菌产ESBLs株检出率在0～26.2%。自2005年起每年均有泛耐药的铜绿假单胞菌和鲍曼不动杆菌的检出。结论该院2004年至2010年多重耐药菌株呈增多趋势,尤其是VRE和泛耐药的铜绿假单胞菌和鲍曼不动杆菌的出现,给临床治疗带来了严峻挑战。     

Antimicrobial profile of ceftazidime: the situation in three larger hospitals in Prague between 1981 and 1983

As a part of preclinical trials of 2,996 clinical isolates from three larger hospitals in Prague were qualitatively and quantitatively assayed for in vitro sensitivity to ceftazidime. In gramnegative bacteria the incidence of resistance to ceftazidime in strain of Enterobacter, Serratia Proteus and Pseudomonas species ranged from 4% to 6% of strains. In grampositive bacteria only strains of enterococci, listeriae and anaerobic bacteria are excluded from the action of this broad-spectrum antibiotic. According to present experiences the antipseudomonal activity of ceftazidime is approximately the same as that of cefsulodine and cefoperazone. Alarmingly, one of the Pseudomonas aeruginosa isolates was found to show a distinct multiresistance to all available lactam, aminoglycoside and broad-spectrum antimicrobials, including ceftazidime.