ObjectiveTo explore the relationship between imipenem-resistant Pseudomonas aeruginosa (IRPA) and outer membrane porin protein OprD2 gene mutation.MethodsIRPA strains (n=30) and imipenem-sensitive Pseudomonas aeruginosa strains (n=30) isolated from the clinical specimens in the First Affiliated Hospital of Chengdu Medical College from December 2018 to December 2019 were collected. Bacteria identification and drug sensitivity experiments were performed by VITEK-2 Compact combined with Kirby-Bauer method. Quantitative real-time polymerase chain reaction was used to detect the expression levels of OprD2 gene in the imipenem-resistant group and the imipenem-sensitive group, and then the strains with decreased expression were sequenced.ResultsThe expression level of OprD2 gene in the imipenem-resistant group was significantly lower than that in the imipenem-sensitive group (P=0.048). Compared with the X63152 sequence, all the 11 Pseudomonas aeruginosa strains with significantly decreased OprD2 expression carried genetic variation, which occurred in coding regions. The variation sites presented diversity. The missense mutation of c.308C→G, c.344A→C, c.379G→C, c.471G→C, c.508T→C, c.553G→C, c.556-558CCG→GGC and c.565-566TG→AC caused amino acid change in the loop L2 and L3 of OprD2 porin, which affected the binding to imipenem. In addition, the mutations at 127, 169-171, 175, 177, 604, 628-630, 688, 719, 785, 826, 828, 842-843, 886, 901, 928-930, 934, 936, 944-945, 1039, 1041 and 1274 all resulted in the changes of amino acid. We also detected a deletion (c.1114-1115delAT) and other nonsense mutations. Large fragment deletion of OprD2 gene occurred in Strain 12. ConclusionsThe mutation and deletion of OprD2 gene can reduce the expression lever of OprD2 gene, leading to the resistance to imipenem of Pseudomonas aeruginosa. The variation of OprD2 gene of IRPA from clinical strains is diverse.
Objectives To retrospectively analyze the isolation rate and drug-resistance of pseudomonas aeruginosa in Fuwai Hospital of Chinese Academy of Medical Sciences from 2013 to 2016. Methods The specimens were collected and cultured. If the isolated bacteria were from the same part of the same patient, the first isolated strains were only counted. The isolated pathogens were identified and the drug-resistance were analyzed. Results A total of 1 404 pseudomonas aeruginosa were isolated. The majority of them were from postoperative recovery room of surgery department (62.1%) and ICU of internal medicine (22.3%). The specimen source were mainly from respiratory tract (75.7%), followed by blood (10.0%) and venous catheter (5.5%). The resistance rate of piperacillin and piperacillin/sulbactam to pseudomonas aeruginosa was 0.6% to 10.4%. The resistance rate of ceftazidime and cefepime was 0.3% to 11.7%. The resistance rate of imipenem and meropenem was 7.6% to 20.1%. The resistance rate of amikacin, gentamicin, and tobramycin was 0.3% to 3.2%. The resistance rate of ciprofloxacin and levofloxacin was 0.6% to 5.2%. Conclusions The isolates of pseudomonas aeruginosa are mainly from postoperative recovery room of surgery department and ICU of internal medicine . Imipenem and meropenem are not the best choices for pseudomonas aeruginosa infection. It has great value to combine piperacillin, piperacillin/sulbactam, ceftazidime and cefepime with aminoglycoside or quinolone antibiotics for the treatment of pseudomonas aeruginosa infection which will reduce drug resistance.
Objective To describe and compare the distributions of aminoglycosides modifying enzymes ( AMEs) in imipenem-resistant Pseudomonas aeruginosa ( IRPA) collected from5 cities in China. Methods A total of 146 strains of IRPA were collected from 5 cities of China ( Chengdu, Hangzhou, Beijing, Shanghai, and Guangzhou) . The polymerase chain reaction ( PCR) were used to amplify the genes of AMEs in IRPA. Results Six positive genotypes were amplified out of 16 genotypes of AMEs by PCR. The total positive rate of AMEs is 65. 06% . The positive rates of genes of aac( 3) -Ⅱ, aac( 6′) -Ⅰ, aac( 6′) -Ⅱ, ant( 2″) -Ⅰ, ant ( 3″) -Ⅰ and aph( 3′) -Ⅵ were 33. 6% , 15. 8% , 19. 9% , 28. 8% , 14. 4%, and 4. 8% , respectively. The genotypes of AMEs were discrepant in different areas as 6 genotypes in Huangzhou and Shanghai, 4 genotypes in Chengdu and Beijing, and 3 genotypes in Guangzhou. Conclusion The results show that the positive rate of AMEs genes is high in IRPA, and the distribution is discrepant among different areas.
ObjectiveTo get a picture of the distribution of aminoglycoside-resistant genes in pseudomonas aeruginosa in China. MethodsWe electronically searched CBM, CNKI, VIP and WanFang Data for studies that reported aminoglycoside-resistant genes in pseudomonas aeruginosa in China from inception to December 2012. Two reviewers independently screened literature according to the inclusion and exclusion criteria, and extracted data. Then statistical analysis was performed using SPSS 17.0 software. ResultsA total of 1 144 strains of aminoglycoside-resistant pseudomonas aeruginosa from 10 provinces/cities were included. The positive rates of aac(3')-I, aac(3')-Ⅱ, aac(6')-I, aac(6')-Ⅱ, ant(2")-I, ant(3")-I and aph(3')-VI of aminoglycoside modifying enzyme genes were 13.3%, 40.1%, 21.6%, 40.3%, 38.1%, 23.7% and 2.9%, respectively to the north of Huai River, while the rates were 3.2%, 20.2%, 15.9%, 37.6%, 28.3%, 28.5% and 9.1%, respectively to the south of Huai River. The positive rates of rmtA, rmtB and armA of 16S rRNA methylases genes were 20.4%, 19.4% and 0.7%, respectively, while other 16S rRNA methylases genes were not found. ConclusionIn China, aminoglycoside modifying enzyme is the primary mechanism of pseudomonas aeruginosa aminoglycoside-resistant drugs, while 16S rRNA methylation enzyme mechanism is secondary.
Objective To investigate the predictors for carbapenem-resistant Acinetobacter baumannii, Enterobacteriaceae and Pseudomonas aeruginosa (CR-AEP) as the pathogens of bloodstream infection (BSI) for intensive care unit (ICU) patients. Methods A retrospective case-control study based on ICU- healthcare-associated infection (HAI) research database was carried out. The patients who have been admitted to the central ICU between 2015 and 2019 in the ICU-HAI research database of West China Hospital of Sichuan University were selected. The included patients were divided into two groups, of which the patients with ICU-acquired BSI due to CR-AEP were the case group and the patients with BSI due to the pathogens other than CR-AEP were the control group. The clinical features of the two groups of patients were compared. Logistic regression model was used to identify the predictors of BSI due to CR-AEP.ResultsA total of 197 patients with BSI were included, including 83 cases in the case group and 114 cases in the control group. A total of 214 strains of pathogenic bacteria were isolated from the 197 BSI cases, including 86 CR-AEP strains. The results of multivariate logistic regression analysis showed that previous use of tigecycline [odds ratio (OR)=2.490, 95% confidence interval (CI) (1.141, 5.436), P=0.022] was associated with higher possibility for CR-AEP as the pathogens of BSI in ICU patients with BSI, while previous use of antipseudomonal penicillin [OR=0.497, 95%CI (0.256, 0.964), P=0.039] was associated with lower possibility for that. Conclusion Previous use of tigecycline or antipseudomonal penicillin is the predictor for CR-AEP as the pathogens of BSI in ICU patients with BSI.
Objective To establish a rat model of chronic pulmonary infection by inoculating Pseudomonas aeruginosa to Sprague-Dawley(SD) rats.Metods Sixty SD rats were divided into 2 groups,ie.the P.aeruginosa group and the control group. Silicone tube precoated with P.aeruginosa was placed into the main bronchus. For the control group, sterile silicon tube was intubated. Results P ． aeruginosa was detected from lung tissue of rats in infected groups.Bacterial number was higher than 103cfu ／ g 28 days after inoculation.The pathological study showed fibrinous proliferation and granulomas formation in the lungs of infected rats 28 days after inoculation.Microscopy examination showed a inflammation predominantly with lymphocyte infiltration.In control group, no bacterial and pathological changes could be detected. Conclusions The animal model with P.aeruginosa chronic pulmonary infection can be established successfully by silicone tubes precoated with P.aeruginosa intubated into the main bronchus.
ObjectiveTo investigate the impact of postoperative application of Pseudomonas aeruginosa injection on recurrence free survival (RFS) and overall survival (OS) in patients with abnormal serum calcitonin levels following surgery for medullary thyroid carcinoma (MTC). MethodsA retrospective collection of data was conducted for 214 patients with abnormal serum calcitonin levels following MTC surgery at West China Hospital of Sichuan University from January 2015 to April 2024. Propensity score matching (1∶2) was utilized to match patients’ data to reduce confounding bias, comparing RFS and OS between patients who used (Pseudomonas group) and did not use (control group) Pseudomonas aeruginosa injection. ResultsAfter propensity score matching, 72 patients with abnormal postoperative calcitonin levels were included, with 24 in the Pseudomonas group and 48 in the control group. The median follow-up time for the 72 patients was 66 months (11–168 months). The 1-year RFS rates for the Pseudomonas group and the control group were 100% and 75.0%, respectively, and the 2-year RFS rates were 87.5% and 56.3%, respectively. The RFS in the Pseudomonas group was superior to that in the control group (χ2=4.791, P=0.029). The 5-year OS rates for the Pseudomonas group and the control group were 90.9% and 93.5%, respectively, with no significant difference between the two groups (χ2=0.469, P=0.491). The Cox proportional hazards regression model indicated that the median RFS was extended in the Pseudomonas group [25 months vs. 21 months, RR=0.350, 95%CI (0.135, 0.900), P=0.029], but there was no significant impact on OS [66 months vs. 69 months, RR=2.22, 95%CI (0.229, 21.444), P=0.503]. ConclusionPostoperative use of Pseudomonas aeruginosa injection in MTC patients with abnormal serum calcitonin level shows significant improvement in RFS, but no significant change in OS.
Objective To explore the overall outcome and its factors of patients with carbapenem-resistant Pseudomonas aeruginosa bloodstream infection (CRPA-BSI). Methods A single-center, retrospective cohort study was carried out. The demographic and clinical data of all emergency patients and inpatients in West China Hospital of Sichuan University from 2017 to 2021 were collected. Firstly, the prognosis of patients with CRPA-BSI was compared with those with carbapenem-sensitive Pseudomonas aeruginosa bloodstream infection (CSPA-BSI). Then Cox regression was used to analyze the factors affecting the prognosis of CRPA-BSI patients. Results A total of 53 patients with CRPA-BSI and 175 patients with CSPA-BSI were enrolled, and they were 1∶1 matched according to the age-adjusted Charlson Comorbidity Index (aCCI) to control for confounding factors. When aCCI was similar, the incidence of poor prognosis in CRPA-BSI patients was significantly higher than that in CSPA-BSI patients [41.5% vs. 18.9%; relative risk=2.20, 95% confidence interval (CI) (1.16, 4.19), P=0.011]. The median length of hospital stay in the CRPA-BSI group was 3 d longer than that in the CSPA-BSI group but the difference was not statistically significant (29 vs. 26 d, P=0.388). With regard to prognostic factors, univariate Cox regression analyses showed that the highest temperature ≤39℃ (P=0.014), hepatobiliary and pancreatic diseases (P=0.011), days of central venous catheterization (P=0.025), days of indwelling urinary catheters (P=0.037), adjustment of medication duration according to drug sensitivity results (P=0.015) and Pitt bacteremia score (P=0.007) were related to the poor prognosis of CRPA-BSI patients. Multiple Cox regression analysis showed that hepatobiliary and pancreatic disease [hazard ratio (HR)=3.434, 95%CI (1.271, 9.276), P=0.015] and Pitt bacteremia score [HR=1.264, 95%CI (1.057, 1.510), P=0.010] were independently associated with poor outcome in CRPA-BSI patients. Conclusions The prognosis of CRPA-BSI patients is worsen than that of CSPA-BSI patients. Hepatobiliary and pancreatic diseases significantly increase the risk of poor outcome in CRPA-BSI patients. Pitt bacteremia score is a predictor of prognosis in patients with CRPA-BSI.
Objective To investigate the mutations of quinolone resistance determinational region ( QRDR) in fluoroquinolon-resistant Pseudomonas aeruginosa strains isolated from patients with nosocomial pneumonia. Methods Eight-four Pseudomonas aeruginosa strains isolated from patients with nosocomial pneumonia in Xinhua Hospital during January 2006 to December 2007, from whom fluoroquinolon-resistant resisitant ( case) and fluoroquinolon-susceptible ( control ) Pseudomona aeruginosa were identified. The mutation of QRDR was tested by restriction fragment length polymorphism ( RFLP) and gene sequencing.The relationship between QRDR mutations and clinical prescription was analyzed. Results Mutation in QRDR was found in 42 isolates among the 50 fluoroquinlon-resisitant isolates( 84. 0% ) , while no mutation was found in fluoroquinlon-susceptible isolates. The mutation in GyrB Ser464 was found in 34 isolates ( 68. 0% ) . There was statistical difference in the usage of β-lactams between the GyrB-Ser464-mutated group and the non-GyrB-Ser464-mutated group( OR = 11. 3, P = 0. 003 and OR = 3. 5, P = 0. 023) , also in the time of fluoroquinolon usage before isolated ( P = 0. 038) . Conclusions The mutation of QRDR is contributing to fluoroquindor-resisitance of Pseudomona aeruginosa, most of which lies in GyrB Ser464.Abuse of β-lactams and fluoroquinolon may be the risk factors of mutation in GyrB Ser464.
Objective To evaluate the efficacy and safety of colistin in the treatment of severe infections. Methods PubMed, ISI Web of Knowledge and Wanfang databases were searched. The initial literatures and references listed in the literature were manually searched. Controlled studies were analyzed using RevMan 5. 0 software.Results Eleven studies were enrolled, including five prospective studies and six retrospective studies. Pooled analysis showed that, compared with other therapies, treatment with colistin in severe infections did not improve 28 or 30-day mortality, clinical symptoms, or bacteria clearance,however, increased the risk of kidney damage. Subgroup analysis showed that colistin did not improve symptoms, mortality ( which was even higher in the patients with drug resistant bacteria infection) , or kidney damage in drug resistant bacteria infections and ventilator associated pneumonia ( VAP) compared with the other antibiotic group. Conclusions Colistin is not superior to the other antibiotics in severe infections.However, there are some shortcomings in our meta-analysis due to limited high-quality RCTs, thus welldesigned RCTs are still needed before final conclusion is made.