Auxotrophy of Pseudomonas aeruginosa in cystic fibrosis

Seventy-four of 403 (18.4%) sputum isolates of Pseudomonas aeruginosa from 49 of 136 (36.0%) adults with cystic fibrosis (CF) were auxotrophic mutants. Two of 11 (18.2%) isolates of P. aeruginosa taken from patients with non-CF bronchiectasis were also auxotrophic. All 99 strains taken from non-bronchiectatic sources were prototrophic. Forty-six of 55 (83.6%) CF auxotrophs required one or more of 36 growth factors tested; the requirements for the remaining 9 isolates were not identified. Methionine was the sole factor required by 17 of 22 (77.3%) isolated which depended on a single factor. We conclude that auxotrophy is a feature of P. aeruginosa infection in cystic fibrosis.     

临床分离铜绿假单胞菌对氟喹诺酮类抗菌药物的耐药性检测

目的了解临床分离铜绿假单胞菌对喹诺酮类等抗菌药物的耐药性。方法琼脂稀释法测定86株铜绿假单胞菌对5种氟喹诺酮类抗菌药物以及头孢吡肟、美罗培南的耐药性。结果铜绿假单胞菌对诺氟沙星、氧氟沙星、左氧氟沙星、环丙沙星、加替沙星的耐药率分别为50%、61.6%、51.2%、48.8%、51.2%;对头孢吡肟和美罗培南的耐药率分别为30.2%、23.2%。结论铜绿假单胞菌对氟喹诺酮类抗菌药物耐药显著,临床应加强检测和监测。     

耐喹诺酮类铜绿假单胞菌的耐药性分析及血清学分型

目的了解广州地区喹诺酮类耐药铜绿假单胞菌的耐药性及泵抑制剂对其耐药水平降低的作用,并调查血清型分布情况。方法用法国生物梅里埃公司的微生物鉴定和药敏分析系统VITEK-2对127株铜绿假单胞菌进行鉴定和药敏检测,并采用羰酰氰基-对-氯苯胺(CCCP)与环丙沙星共同作用,以琼脂稀释法测定耐药菌的最低抑菌浓度(M IC)的变化,同时用玻片凝集法对耐药株进行血清学分型。结果环丙沙星耐药菌对哌拉西林/他唑巴坦(65.5%)的敏感率最高,只有阿米卡星(64.4%)、哌拉西林(51.7%)和妥布霉素(50.6%)的敏感率大于50.0%,而敏感菌对美罗培南(97.5%)及左氧氟沙星(97.5%)的敏感率最高,妥布霉素(95.0%)次之,对临床常用的13种抗生素,耐药菌较敏感菌的敏感性明显降低(P值均<0.001);耐药菌受泵抑制CCCP作用,M IC降低1~4个稀释度;血清分型率为93.1%,耐药菌的血清型以B型(20.7%)和L型(19.5%)为主。结论耐喹诺酮类铜绿假单胞菌对临床常用抗生素的敏感性降低,并呈多重耐药,使用抗生素 泵抑制剂可提高药物对铜绿假单胞菌的敏感性;血清学分型可以快速简单地监测铜绿假单胞菌在医院内的流行情况。     

Simple co-agglutination assay for rapid identification of Pseudomonas aeruginosa

A new co-agglutination assay for the identification of Pseudomonas aeruginosa from culture was developed and evaluated. A total of 232 P. aeruginosa isolates, and 36 oxidase-positive, Gram-negative clinical isolates were tested. The sensitivity of the assay was 96%, and the specificity was 91.9%. The assay took <15 min to perform.     

Susceptibility of Pseudomonas aeruginosa to Gentamicin Sulfate In Vitro: Lack of Correlation Between Disc Diffusion and Broth Dilution Sensitivity Data

Seventy-eight of 420 clinical isolates of Pseudomonas aeruginosa yielded zones of inhibition of less than 12 mm in diameter around 10-mug discs of gentamicin sulfate when tested by the standardized Bauer-Kirby disc diffusion method. Of 153 strains chosen from these isolates, one strain (0.65%) required 25 mug of gentamicin per ml for inhibition; the remainder (99.35%) were inhibited by 6 mug/ml or less of the antibiotic. It is recommended that those isolates of P. aeruginosa that yield zones of inhibition less than 12 mm in diameter be disc susceptibility-tested once more; those isolates that give zones of inhibition of less than 12 mm upon repeated examination should then be subjected to the broth dilution test before they are designated as sensitive or resistant to gentamicin.     

Co-existence of colonies with different serotypes and other biological characteristics in clinical isolates of Pseudomonas aeruginosa.

The biological characteristics of individual colonies of Pseudomonas aeruginosa from 138 specimens were investigated. Of these isolates, 90 (65.2%) formed colonies of similar appearance and morphology, and 48 (34.8%) formed colonies which differed either in appearance or morphology. The individual colonies of 138 isolates were tested for serotype. The former 90 isolates formed only the colonies with one kind of serotype, whereas 17 of the latter 48 isolates formed the colonies with more than one kind of serotype. All the 9 isolates tested also differed in other biochemical characteristics: acid productions from xylose, mannitol and maltose, urease production and gelatin liquefaction. beta-Lactamase activity was investigated in 7 isolates forming colonies with more than one serotype. There were no marked differences in beta-lactamase activity among the different colonies in 5 isolates but marked differences among those in the other 2 isolates.     

Resistance of urinary tract infection pathogens and choice of antibacterial therapy in pediatric urologic practice]

The data on antibiotic resistance of the main uropathogens isolated from patients with urinary tract infection in an urologic department (319 isolates) and outpatient and diagnostic units (360 isolates) are presented. It was shown that by the antibiotic resistance the Escherichia coli isolates from the urologic department patients and outpatients did not practically differ: 44.1 and 47.8% of the isolates were resistant to ampicillin, 26.7 and 23.4% were resistant to amoxycillin/clavulanate, 28.9 and 24.9% were resistant to co-trimoxazole and 26.5% was resistance to cefuroxime (outpatients). The basic differences referred to Pseudomonas aeruginosa: resistance to ceftazidime in 38.5% of the isolates and resistance to gentamicin in 36.2% of the isolates. The activity against P. aeruginosa could be arranged as follows in the decreasing order: amikacin = meropenem > imipenem > cefepime = cefoperazone/sulbactam > gentamicin = ceftazidime. Resistance of P. aeruginosa to fluoroquinolones (ciprofloxacin and levofloxacin) remained low (7.4 and 8.0% respectively). No ampicillin resistance was revealed in the isolates of Enterococcus faecalis.     

Molecular characterization of Pseudomonas aeruginosa isolates resistant to all antimicrobial agents, but susceptible to colistin, in Daegu, Korea

Multi-drug resistant Pseudomonas aeruginosa has been implicated in a variety of serious therapeutic problems in clinical environments. Among the 968 P. aeruginosa isolates obtained from two hospitals in Daegu, Korea, we acquired 17 isolates that were resistant to all available tested antimicrobial agents, with the exception of colistin (colistin-only sensitive). We characterized the antimicrobial susceptibilities, metallo-beta-lactamases, and epidemiological relatedness among the colistin-only sensitive P. aeruginosa isolates. All colistin-only sensitive isolates were positive in the modified Hodge test and imipenem-EDTA synergy test, thereby indicating the production of metallo-beta-lactamases. 11 isolates from the secondary hospital and six isolates from the tertiary teaching hospital harbored blaVIM-2 and blaIMP-1, respectively. The pulsed-field gel electrophoretic analysis of the SpeI-digested DNA from P. aeruginosa isolates indicated that two different clones of colistin-only sensitive P. aeruginosa originated from each hospital, and had spread within the hospital environment. Overall, colistin-only sensitive P. aeruginosa was detected in Korea for the first time, but no pan-drug resistant bacteria were identified. Nationwide surveillance is required in order to monitor the emergence of colistin-only sensitive or pan-drug resistant bacteria.     

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.     

Characterization by pyocine typing and serotyping of oral and sputum strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients

Oral and sputum isolates of Pseudomonas aeruginosa in patients with cystic fibrosis were investigated. Of the 17 patients studied, 12 patients (71%) yielded both mucoid and nonmucoid variants of Pseudomonas aeruginosa from sputum and (or) various oral ecological sites, such as buccal mucosa, tongue dorsum, dental plaques, and saliva. A total of 51 strains of mucoid and nonmucoid Pseudomonas aeruginosa were isolated from these patients and were phenotypically characterized by both pyocine typing and serotyping. Five patients (42%) were colonized or infected by a single strain of Pseudomonas aeruginosa, whereas 7 patients (58%) were cocolonized or coinfected by two or more phenotypically different strains of Pseudomonas aeruginosa. To understand the mechanisms involved in Pseudomonas aeruginosa colonization, it may be necessary to identify multiple isolates of Pseudomonas aeruginosa not only from the sputum but also from the various oral ecological sites and to further explore the role of the oral cavity in this colonization.     

Changing the epidemiology of carbapenem-resistant Pseudomonas aeruginosa in a Brazilian teaching hospital: the replacement of São Paulo metallo-β-lactamase-producing isolates

In Brazil, carbapenem-resistant Pseudomonas aeruginosa isolates are closely related to the S?o Paulo metallo-β-lactamase (SPM) Brazilian clone. In this study, imipenem-resistant isolates were divided in two sets, 2002/2003 and 2008/2009, analysed by pulsed field gel electrophoresis and tested for the Ambler class B metallo-β-lactamase (MBL) genes blaSPM-1, blaIMP and blaVIM. The results show a prevalence of one clone related to the SPM Brazilian clone in 2002/2003. In 2008/2009, P. aeruginosa isolates were mostly MBL negative, genetically diverse and unrelated to those that had been detected earlier. These findings suggest that the resistance to carbapenems by these recent P. aeruginosa isolates was not due to the spread of MBL-positive SPM-related clones, as often observed in Brazilian hospitals.     

Comparison of three methods for identifying nonfermenting gram-negative rods.

Seventy-six strains of nonfermenting gram-negative rods were tested on the Analytab Products, Inc. (API) system and on conventional media. In addition, 51 strains were tested on the Oxi-Ferm system. When the identification results were compared, the API agreed with the conventional system on 41% of the isolates and Oxi-Ferm agreed with the conventional system on 72% of the isolates. API had the greatest difficulty in identifying Pseudomonas aeruginosa. API and Oxi-Ferm both had difficulty identifying P. cepacia. Oxi-Ferm had more individual discrepant biochemical reactions than did API when compared to the conventional media, but still maintained a higher percentage agreement with the conventional system.     

圈养林麝铜绿假单胞菌的分离鉴定及耐药性和病原特性分析

【背景】铜绿假单胞菌感染所致的化脓性疾病是困扰林麝驯养的重要因素,是一类较难防治的细菌性疾病,目前尚无疫苗可用来预防该病。【目的】研究林麝源铜绿假单胞菌的感染现状和分子流行病学规律。【方法】对2014年10月至2015年10月四川宝兴和陕西镇坪两个林麝养殖中心发病林麝中铜绿假单胞菌进行分离鉴定,并对其耐药情况进行分析,利用脉冲场凝胶电泳(PFGE)分型技术研究分离菌的PFGE指纹图谱,探究其流行病学趋势,并对部分菌株的致病性进行分析。【结果】分离得到60株铜绿假单胞菌,其中34株来自镇坪,26株来自宝兴。耐药结果表明:60株林麝源铜绿假单胞菌对17种抗菌药物呈现不同程度耐药性,不同地区和不同样本源间分离的铜绿假单胞菌对17种抗菌药物的耐药性总体趋于一致,多重耐药情况严重,以5耐、6耐为主。分型结果显示:60株铜绿假单胞菌PFGE图谱的相似性为49.1%-100%。经聚类分析得到A-O共15种基因簇,其中优势基因簇为C、E、G、J。致病性结果表明,流行菌株的致病力强弱依次为:动物源菌株环境源菌株,且主要流行菌株(基因簇E、F、J)的致病力大于其余菌群。【结论】铜绿假单胞菌在两地区具有水平传播的途径,本研究可为跨地区林麝化脓性炎症的防控提供理论依据。     

Susceptibility to chemotherapeutics and the occurrence of metallo-beta-lactamases in hospital Pseudomonas aeruginosa strains

The aim of the study was evaluation of susceptibility of Pseudomonas aeruginosa strains isolated from patients hospitalized in different wards of Rydygier's Hospital in Krakow in 2005. Bacteria were identified on the basis of typical morphology confirmed by Gram-staining microscopy and by biochemical tests--ID 32 GN strips using ATB system (bioMerieux, France). The susceptibility of all isolates to a panel of antimicrobial agents was performed using disk diffusion method. The highest in vitro activity against clinical strains demonstrated ceftazidime (88.6% of susceptible strains) while the lowest in vitro activity against clinical strains demonstrated imipenem (50.4% of susceptible strains). It was also observed that 40.2%(53) of strains were resistant to meropenem and imipenem. Carbapenem resistant P aeruginosa strains were tested for MBL production. We performed disk synergy test for MBL detection with EDTA, 2-MPA and ceftazidime, imipenem. The presence of a distorted inhibition zone was interpreted as a positive result for MBL production. Positive results of disk synergy tests were confirmed by Etest MBL strips. Metalo-beta-lactamases were detected in 13 isolates resistant to carbapenems.     

PER-1 is still widespread in Turkish hospitals among Pseudomonas aeruginosa and Acinetobacter spp

PER-1 type beta-lactamases were screened among ceftazidime-resistant clinical isolates of Acinetobacter spp. and Pseudomonas aeruginosa. A total of 176 non-repetitive isolates (84 Acinetobacter spp. and 92 P. aeruginosa) were collected during a three month surveillance period. Isolates were obtained from seven intensive care units of seven university hospitals. All strains were screened for bla(PER-1) alleles by PCR. Of the strains, 31% and 55.4% of Acinetobacter spp. and P. aeruginosa were positive for bla(PER-1) type genes, respectively.     

Microbiological monitoring for the causative agents of nosocomial infections (exemplified by resuscitation and intensive therapy units)]

More than 900 isolates from at least 1500 patients were tested within 1996-1998. Gram-negative organisms were the main pathogens isolated from patients with different forms of nosocomial complications such as late pneumonia, associated with artificial ventilation of the lungs, and various secondary wound or urinary tract infections. The prevalence of Pseudomonas aeruginosa was stated. Antibioticograms showed that the most active drugs were imipenem (more than 90 per cent of the susceptible isolates) and ticarcillin/clavulanate (48-58 per cent of the susceptible isolates). The activity of ticarcillin/clavulanate (Timentin) was practically the same as that of imipenem against 21 strains of P.aeruginosa isolated from the blood and cerebrospinal fluid of 21 patients with sepsis and 3 patients with secondary purulent meningitis.     

Production of cytotoxin by clinical strains of Pseudomonas aeruginosa

Presence of cytotoxin was studied in extracts of 57 strains of Pseudomonas aeruginosa (46 bacteremia, 4 environmental, and 7 Fisher immunotype), 10 Pseudomonas species, and 7 nonpseudomonas isolates. Cytotoxin was identified by Western immunoblot in extracts of all P. aeruginosa isolates. None of the Pseudomonas species or nonpseudomonas isolates were shown to produce this protein. No immunologic cross-reactivity was observed between cytotoxin antibody and P. aeruginosa alkaline protease, toxin A, or elastase. In partially purified extracts of two bacteremia strains and PA 158 (parent strain for cytotoxin production), detection of cytotoxin by Western immunoblot was correlated with biological activity, as measured by the cell swelling assay. Cytotoxin appears to be produced by all strains of P. aeruginosa and biological activity can be demonstrated in extracts of the strains tested. This biological activity is neutralized by specific antibody. Because of its known marked cytotoxic effect on most eukaryotic cells, P. aeruginosa cytotoxin might be an important factor in the pathogenesis of P. aeruginosa infections.     

Occurrence and antimicrobial resistance of Gram-negative bacteria isolated in haemodialysis water and dialysate of renal units: results of a Greek multicentre study

AIMS: To evaluate the occurrence, identity and antimicrobial resistance of Gram-negative bacteria isolated from municipal water supplies, treated water, and dialysate of all 85 Greek haemodialysis centres. METHODS AND RESULTS: A total of 141 Gram-negative bacterial isolates (98 non-fermentative and 43 enterobacteria) were recovered from 255 water samples. Twenty-four of them were isolated from tap water, 31 from treated water, and 86 from dialysate samples. The mean concentrations (CFU per 100 ml +/- s.d.) of the positive Gram-negative bacteria samples were 69.2 +/- 43.9, 31.2 +/- 28.7 and 3552.3 +/- 4485.0, respectively. The most common isolates, in order of frequency were Pseudomonas aeruginosa (22.7%), Chryseobacterium meningosepticum (14.9%), Stenotrophomonas maltophilia (13.5%), Escherichia coli (12.8%) and Enterobacter cloacae (7.8%), representing 71.6% of all isolates. Ps. aeruginosa was the most prevalent isolate in all types of water sample followed by C. meningosepticum in tap and treated water and by E. coli in dialysate. Nineteen per cent of the enterobacteria and 35% of the non-fermenters were resistant against three or more of the nine antibiotics tested. CONCLUSIONS: These data suggest that dialysate and treated water could be a source of infection for several non-fermentative and enterobacterial species. IMPACT OF THE STUDY: Microbiological monitoring of such samples is needed in order to know the identity and antibiotic resistance profiles of their potentially pathogenic bacterial population.     

Prevalence and genotypic relatedness of carbapenem resistance among multidrug-resistant P. aeruginosa in tertiary hospitals across Thailand

ABSTRACT: BACKGROUND: Increased infection caused by multidrug resistant (MDR) Pseudomonas aeruginosa has raised awareness of the resistance situation worldwide. Carbapenem resistance among MDR (CR-MDR) P. aeruginosa has become a serious life-threatening problem due to the limited therapeutic options. Therefore, the objectives of this study were to determine the prevalence, the antibiotic susceptibility patterns and the relatedness of CR-MDR P. aeruginosa in tertiary hospitals across Thailand. METHODS: MDR P. aeruginosa from eight tertiary hospitals across Thailand were collected from 2007--2009. Susceptibility of P. aeruginosa clinical isolates was determined according to the Clinical and Laboratory Standards Institute guideline. Selected CR-MDR P. aeruginosa isolates were genetically analyzed by pulsed-field gel electrophoresis. RESULTS: About 261 clinical isolates were identified as MDR P. aeruginosa and approximately 71.65% were found to be CR-MDR P. aeruginosa. The result showed that the meropenem resistance rate was the highest reaching over 50% in every hospitals. Additionally, the type of hospitals was a major factor affecting the resistance rate, as demonstrated by significantly higher CR-MDR rates among university and regional hospitals. The fingerprinting map identified 107 clones with at least 95% similarity. Only 4 clones were detected in more than one hospital. CONCLUSIONS: Although the antibiotic resistance rate was high, the spreading of CR-MDR was found locally. Specific strains of CR-MDR did not commonly spread from one hospital to another. Importantly, clonal dissemination ratio indicated limited intra-hospital transmission in Thailand.     

北京地区实验动物绿脓杆菌分离株MLVA分型

目的通过多位点可变数目串联重复序列分析（multiple-locus variable-number tandem-repeat analysis,MLVA）分型方法,研究北京地区实验动物绿脓杆菌分离株基因型和分布情况。方法选择13个可变数目重复序列（variable-number tandem-repeat,VNTR）位点,对实验动物及设施中检测出的141株绿脓杆菌的基因组DNA进行重复序列扩增,所得指纹图谱使用BioNumerics软件进行聚类分析,绘制系统发育树和最小生成树（minimum spanning tree,MST）。结果所采用的13个VNTR位点能够对全部分离株进行有效分型。141株绿脓杆菌主要被分为了3个基因群,56个基因型。各群所占比例分别为A群82.3%,B群占12.8%,C群占5.0%,辛普森多样性指数为0.763。同一区域内相邻实验动物单位的绿脓杆菌分离株同源关系较远。结论 MLVA方法对绿脓杆菌具有很好的分型能力,能够有效的追踪绿脓杆菌的来源。北京地区实验动物中绿脓杆菌分离株基因型多态性丰富,但无地域性同源关系。