Effect of inhaled tobramycin on early Pseudomonas aeruginosa colonisation in patients with cystic fibrosis

Early antibiotic treatment of airway colonisation with Pseudomonas aeruginosa can delay onset of chronic lung infection in patients with cystic fibrosis. Whether the pathogen is eradicated by this treatment is unclear. We successfully eradicated the organism in 14 of 15 patients with cystic fibrosis who had been colonised by P aeruginosa. Patients inhaled 80 mg tobramycin twice daily for 12 months. Eradication was confirmed by sequential respiratory cultures and serum antibody titres that were negative for P aeruginosa. Our antibiotic therapy regimen maintained pulmonary function at high levels.     

Epidemiology and clinical outcomes of patients with multiresistant Pseudomonas aeruginosa.

We conducted a case-series study of multiresistant Pseudomonas aeruginosa in patients who did not have cystic fibrosis. Patient characteristics, antibiotic exposures, time course of emergence of resistance, and clinical outcomes were examined. Twenty-two patients were identified from whom P. aeruginosa resistant to ciprofloxacin, imipenem, ceftazidime, and piperacillin was isolated. Nineteen (86%) had clinical infection. Patients received prolonged courses of antipseudomonal antibiotics before isolation of multiresistant P. aeruginosa. Nine of 11 patients with soft-tissue infection exhibited resolution of clinical infection but usually required surgical removal of infected tissue with or without revascularization. Overall, three patients died. In two instances in which multiple isolates with different susceptibility profiles from the same patient were available, pulsed-field gel electrophoresis profiles of serial isolates were indistinguishable or closely related. This study illustrates that multiresistant P. aeruginosa emerges in a stepwise manner after exposure to antipseudomonal antibiotics and results in adverse outcomes.     

PCR identification and automated ribotyping of Pseudomonas aeruginosa clinical isolates from intensive care patients

Nosocomial isolates of Pseudomonas aeruginosa exhibit high rates of resistance to antibiotics, and are often multidrug resistant. P. aeruginosa clinical isolates (n = 56) were obtained from ICU patients in a hospital in Pakistan over a 3-y period. Antimicrobial susceptibility of the 56 P. aeruginosa clinical isolates was investigated using 7 antibiotics and the resistance rates were as follows: aztreonam (68% resistant), ceftazidime (67%), imipenem (66%), ofloxacin (59%), amikacin (56%), gentamicin (44%), and piperacillin-tazobactam (27%) (p < 0.01). In addition, 55% of the P. aeruginosa clinical isolates were resistant to 4 or more antibiotics. Imipenem-resistant strains were frequently associated with ceftazidime, ofloxacin, aztreonam, and more strikingly, amikacin resistance (p < 0.05). PCR (using P. aeruginosa-specific primers VIC1 + VIC2 and P1 + P2, respectively) was highly specific and sensitive, and was positive for all 56 P. aeruginosa isolates tested. Automated ribotyping was used to investigate the clonal diversity of the 56 P. aeruginosa isolates. Automated ribotyping indicated that the clinical isolates were clonally related and could be clustered into 4 major ribogroups based on their similarity index, with ribogroup II being the dominant one. The P. aeruginosa isolates in ribogroup II were correlated with their antibiotic resistance pattern and, interestingly, there seemed to be a gradual acquisition of multiple antibiotic resistance associated with the isolates within this group over time. The ribotyping data, together with the antibiotic resistance profile, provide valuable molecular epidemiology information for the control of hospital-acquired P. aeruginosa infections.     

Effects of azithromycin on clinical isolates of Pseudomonas aeruginosa from cystic fibrosis patients

There is considerable interest in the use of azithromycin for the treatment of lung disease in patients with cystic fibrosis (CF). Although its mechanism of action as an inhibitor of bacterial protein synthesis has been well-established, it is less clear how azithromycin ameliorates the lung disease associated with Pseudomonas aeruginosa, which is considered to be resistant to the drug. We tested the effects of azithromycin on clinical isolates (CIs) from CF patients and compared them with laboratory reference strains to establish how this drug might interfere with the production of bacterial virulence factors that are relevant to the pathogenesis of airway disease in CF patients. Azithromycin inhibited P aeruginosa PAO1 protein synthesis by 80%, inhibiting bacterial growth and the expression of immunostimulatory exoproducts such as pyocyanin, as well as the gene products necessary for biofilm formation. In contrast, the effects of azithromycin on CIs of P aeruginosa were much more variable, due in large part to their slow growth and limited exoproduct expression. Culture supernatants for two of three clinical strains induced appreciable CXCL8 expression from cultured epithelial cells. Azithromycin treatment of the organisms inhibited 65 to 70% of this induction; azithromycin had no direct effect on the ability of either normal cells or CF epithelial cells to produce CXCL8. Azithromycin does decrease the P aeruginosa synthesis of immunostimulatory exoproducts and is likely to be most effective against planktonic, actively growing bacteria. This effect is less predictable against CIs than the prototypic strain PAO1.     

Multidrug-resistant Pseudomonas aeruginosa and mortality in mechanically ventilated ICU patients

BackgroundThe link between bacterial resistance and prognosis remains controversial. Predominant pathogen causing ventilator-associated pneumonia (VAP) is Pseudomonas aeruginosa (Pa), which has increasingly become multidrug resistant (MDR). The aim of this study was to evaluate the relationship between MDR VAP Pa episodes and 30-day mortality.MethodsFrom a longitudinal prospective French multicenter database (2010-2016), Pa VAP onset and physiological data were recorded. MDR was defined as non-susceptibility to at least 1 agent in 3 or more antimicrobial categories. To analyze if MDR episodes were associated with greater in-hospital 30-day mortality, we performed a multivariate survival analysis using the multivariate nonlinear frailty model.ResultsA total of 230 patients presented 286 Pa VAP. A maximum of 3 episodes per patient was observed; 73 episodes were MDR and 213 were susceptible. In the multivariate model, factors independently associated with 30-day mortality included hospitalization in the 6 months preceding the first episode (hazard ratio [HR], 2.31; 95% confidence interval [CI], 1.50-3.60; P = .0002), chronic renal failure (HR, 2.34; 95% CI, 1.15-4.77; P = .0196), and Pa VAP recurrence (HR, 2.29; 95% CI, 1.79-4.87; P = .032). Finally, MDR Pa VAP was not associated with death (HR, 0.87; 95% CI; 0.52-1.45; P = .59).ConclusionsThis study did not identify a relationship between the resistance profile of Pseudomonas aeruginosa and mortality.     

耐亚胺培南铜绿假单胞菌外膜蛋白D基因突变检测

目的探讨耐亚胺培南铜绿假单胞菌临床分离株外膜蛋白D（oprD）基因突变与耐药关系.方法应用随机扩增DNA多态性分析（RAPD）技术对10株耐亚胺培南铜绿假单胞菌临床分离株进行DNA分型,并对不同克隆耐药株oprD基因编码区进行全基因扩增测序和金属酶检测.结果 10株耐亚胺培南铜绿假单胞菌均不产金属酶,可分为4个不同克隆.与X63152序列比较,所有耐药菌株oprD基因发生显著变异,变异率大于50%.30、11、9、20、31号克隆株编码区276～387 bp之间发生多处点突变,其中308 bp G→C突变使其编码的苏氨酸被丝氨酸代替,344 bp C→A突变使其编码的赖氨酸被苏氨酸代替,393～412位有20 bp DNA片段缺失,其后的核苷酸序列发生移码突变.13、21号克隆株编码区264～273位有10 bp DNA片段缺失,产生移码突变,形成终止密码子TAA（319～321 bp）.1号克隆株和22号克隆株oprD基因分别发生大片段的碱基置换和多处点突变,变异率分别为54.03%和74.89%.结论耐亚胺培南铜绿假单胞菌临床分离株oprD基因变异具有多样性.     

Proteases of Pseudomonas aeruginosa in patients with cystic fibrosis

Radioimmunoassays were used to determine titers of antibody to alkaline protease (AP) and elastase (Ela) produced by Pseudomonas aeruginosa in sera and bronchial secretions, in vitro production of AP and Ela by P. aeruginosa isolates, and occurrence of these enzymes in bronchial secretions from patients with cystic fibrosis. Titers of serum antibodies to AP ranging from 1:10 to 1:545 and to Ela ranging from 1:10 to 1:725 were found in 83%-88% of patients with cystic fibrosis and chronic lung infections due to P. aeruginosa. Antibody titers in liquified bronchial secretions were approximately 10% of the serum titers. Thirty-one (93%) of 34 isolates produced both proteases in vitro in comparable amounts (concentration of protease in culture supernatant: AP, 0.01-480 micrograms/ml; Ela, 0.02-490 micrograms/ml). AP and Ela were detected in vivo when antibodies to the enzymes were absent. The results suggest that specific immune responses in patients with cystic fibrosis neutralize proteases of P. aeruginosa.     

ICU 铜绿假单胞菌临床分布及耐药性分析

目的：调查 ICU 铜绿假单胞菌临床分布及耐药性分析,为临床诊断及合理应用抗生素提供科学依据。方法选择济宁医学院附属医院 ICU 一区2013年9月至2014年9月住院患者的临床标本进行常规细菌培养鉴定,以 K-B 纸片扩散法进行药物敏感性试验,对分离出的铜绿假单胞菌药敏试验结果进行统计分析。结果从各种标本中共分离到铜绿假单胞菌216株,其中呼吸道标本痰液百分比最高,占69%。在15种抗生素药敏试验中阿米卡星、头孢哌酮舒巴坦钠、头孢吡肟体外抗菌活性最好,铜绿假单胞菌株耐药性强,产生多重耐药菌63株。结论 ICU 铜绿假单胞菌感染主要为呼吸道感染,ICU中铜绿假单胞菌耐药率较高,应引起高度重视,要加强病原学检测,以有效控制感染。     

Resistance to imipenem in Pseudomonas aeruginosa: clinical experience and biochemical mechanisms

Emergence of resistance to imipenem during therapy for Pseudomonas aeruginosa infections is common and may result in treatment failure. Resistance emerges most often during therapy for lower respiratory tract infections. There are several unique features of this resistance to imipenem. First, cross-resistance to other beta-lactam agents is not observed. Second, the mechanism of resistance in most of the isolates studied to date appears to be related to a selective permeability barrier across the bacterial outer membrane, usually associated with discrete alterations in the electrophoretic profiles of outer membrane proteins. These data suggest that imipenem may traverse the outer membrane of P. aeruginosa via a specific porin protein that is not critical for penetration of other beta-lactam antibiotics.     

肺心病患者绿脓杆菌分型耐药质粒DNA分子杂交的临床意义

对８所医院住院肺心病患者痰培养获绿脓杆菌（ＰＡ）６００株进行分型分析，结果Ｐ６型占２５．６％。不同地区和医院的假单胞菌及ＰＡ型别分布不同，可作为流行病学调查依据。１５０株中的６８株ＰＡ含有质粒，用β－内酰胺酶和氨基苷钝化酶耐药基因探针各６种，与６０株含质粒的ＰＡ菌落杂交，证实从院内感染患者分离到的３株ＰＡ均带有ＯＸＡ－２、ＡＡＣ（６＇）－１ｂ同源的ＤＮＡ序列并均来自同一个菌株，在传播院内感染时，又     

Fluoroquinolone-resistant Pseudomonas aeruginosa: assessment of risk factors and clinical impact

Purpose

Pseudomonas aeruginosa infections have been associated with considerable morbidity and mortality. Fluoroquinolones (FQ) are the only oral therapy available for P. aeruginosa infections, but resistance is increasingly prevalent.

Methods

We examined annual trends in FQ-resistant P. aeruginosa (FQRPA) from 1991 to 2000. Subsequently, inpatients with a clinical culture positive for P. aeruginosa between January 1, 1999 and December 31, 2000 were included in a case control study to identify risk factors for FQ resistance and a cohort study to examine the impact of FQ resistance on outcomes in P. aeruginosa.

Results

Annual prevalence of FQRPA increased from 15% in 1991 to 41% in 2000 (P <0.001 trend). Between 1999 and 2000, 332 P. aeruginosa isolates were FQ resistant and 540 were FQ susceptible. Prior FQ use was the only independent risk factor for FQRPA (adjusted OR = 3.43; 95% confidence interval [CI] 2.37, 4.96). Subjects with FQRPA had greater median hospital charges ($62,325 vs $48,734) (P =.007) and higher mortality (47.5% vs 35.5%) (P =.004). However, in a multivariate model, only imipenem resistance of the isolate was significantly associated with mortality. FQ resistance was not an independent risk factor.

Conclusions

FQRPA has increased significantly and is associated with prior FQ use. Limiting FQ use may curb the emergence of resistance among P. aeruginosa. FQRPA is associated with increased hospital charges, but other resistance patterns may have a more significant impact on mortality.