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Genotypes of Aminoglycosides Modifying Enzymes in Imipenem-Resistant Pseudomonas Aeruginosa

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.

Study of OprD2 gene polymorphism in imipenem-resistant Pseucionionas aeruginosa

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.

无外伤铜绿假单胞菌性全眼球炎一例

抗菌药物对铜绿假单胞菌引起的呼吸机相关性肺炎患者下呼吸道菌群变化的影响

目的探讨由铜绿假单胞菌引起的呼吸机相关性肺炎（VAP）患者经抗菌药物治疗后，其下呼吸道菌群的变化情况。 方法纳入济宁市第一人民医院重症医学科（ICU）2010年9月至2012年9月间培养出铜绿假单胞菌且临床肺部感染评分≤6分的54例VAP患者。将患者随机分为抗菌药物组（头孢他啶+阿米卡星，n=28）与对照组（n=26），治疗7 d后，再次行下呼吸道分泌物培养，分别观察两组未培养出细菌（培养阴性率）以及转变为其他细菌的例数（菌群变化率）。 结果抗菌药物组中细菌培养阴性者10例（占35.7%），菌群变化者11例（占39.3%，且包含2例多重耐药铜绿假单胞菌）。对照组中细菌培养阴性者11例（占42.3%），菌群变化者3例（占11.5%）。两组间细菌培养阴性率差异无统计学意义（35.7%比42.3%，P>0.05），而抗菌药物组菌群变化率则明显高于对照组（39.3%比11.5%，P < 0.05）。 结论在铜绿假单胞菌引起的临床肺部感染评分≤6分的VAP患者，经抗菌药物治疗后易导致其下呼吸道菌群发生变化，甚至多重耐药菌的出现。

Effect of local spraying of Pseudomonas aeruginosa injection on recurrent laryngeal nerve after total thyroidectomy and bilateral central lymph node dissection

ObjectiveTo evaluate the safty of recurrent laryngeal nerve (RLN) and parathyroid if Pseudomonas aeruginosa injection (PAI) is used after total thyroidectomy and central neck dissection (CND).MethodsFrom Mar. 2016 to Oct. 2017, we recruited 113 patients with papillary thyroid cancer (PTC) who accepted total thyroidectomy and CND. During operation, 1 mL of PAI was applied in 58 patients (local spray group) and 55 not (control group). The hoarseness, hypoparathyroidism, chylous fistula, drainage volume, hospital stay, and incidence of complications were compared between the two groups.ResultsThe two groups embraced few difference in age, gender, BMI, tumor site, the diameter of tumor and the number of metastatic and the harvested lymph nodes (P>0.05). There were nobody who has suffered in hoarseness and permanent hypoparathyroidism in both groups at any time after operation. There was no significant differences of complication between the two groups. The drainage volume at 24 h after operation in the local spraying group was more than that in the control group, and the difference was statistically significant (P=0.023). There were 2 patients had chylous fistula after surgery in the control group but none in the local spray group. The total volumes of drainage, incidence of fever and incision infection, the mean stay in the hospital, and the postoperative pain score had no statistic significance in the both groups.ConclusionAfter total thyroidectomy and CND, local spraying of PAI in the wound cavity is safe and will not damage the recurrent laryngeal nerve.

Infection Status and Risk Factors of Nosocomial Infections Caused by Imipenemresistant Pseudomonas Aeruginosa

摘要:目的:探讨老年耐亚胺培南铜绿假单胞菌(IRPA)感染的危险因素以指导临床救治。 方法:采用病例对照研究,选取四川省人民医院干部科2006年1月~2008年12月IRPA院内感染老年患者32例,并随机选择同时期敏感铜绿假单胞菌院内感染48例作为对照,采用单因素(t检验,χ2检验)及多因素Logistic回归进行分析。结果:IRPA分离率为34.8%,IRPA对抗生素的耐药性远远高于敏感铜绿假单胞菌组,但对阿米卡星敏感率达81.3%。单因素分析发现,下列因素与IRPA感染有关:高龄、住院时间≥4周、高急性生理和慢性健康状况(APACHEⅡ)评分、慢性肺部疾病(慢性阻塞性肺疾病COPD/支气管扩张)、分离出IRPA前2周用过亚胺培南/美罗培南、早期联用抗生素、院内获得性肺炎(HAP)。多因素Logistic回归分析表明:长程住院［比值比(OR)= 14.887］,APACHEⅡ评分≥16分(OR=38.908)以及分离出IRPA前2周用过亚胺培南/美罗培南(OR =12.945)是IRPA感染的独立危险因素。结论:长程住院、APACHEⅡ评分≥16分以及亚胺培南/美罗培南的使用是IRPA感染的危险因素。IRPA对阿米卡星敏感率相对较高,但治疗难度大。Abstract: Objective: To study the infection status and risk factors of nosocomial infection caused by imipenemresistant Pseudomonas aeruginosa (IRPA) in elderly patients. Methods: By a casecontrol study, the data of 32 cases of IRPA nosocomial infections were analyzed from Jan. 2006. to Dec. 2008 in cadres Ward of Sichuan Provincial People’s Hospital; 48 cases of Imipenemsensitive pseudomonas aeruginosa infection were randomized as control. Univariate analysis (T test and chisquare test )and multivariate logistic regression analysis were used for statistics. Results: The resistance to antibiotics of IRPA is much higher than the sensitive group.81.3％ of IRPA were sensitive to amikacin. According to univariate analysis,the factors associated with the infection caused by IRPA were age, length of stay in hospital more than 4 weeks, high score of APACHEⅡ, chronic pulmonary disease (COPD/bronchiectasis),imipenem/meropenem used 2 weeks before isolation of IRPA, early combination therapy of antibiotics and hospital acquired pneumonia (HAP). Multivariate logistic regression analysis identified three independent factors: Length of stay in hospital more than 4 weeks, APACHEⅡ score≥16 and imipenem/meropenem used 2 weeks before isolation of IRPA. Conclusion: Long length of stay in hospital, APACHEⅡ score ≥16 and previous imipenem/meropenem use were independent risk factors for IRPA infection. Although the sensitivity of IRPA to amikacin was relatively high, it was difficult to treat in clinical practice.

Role of CD4+CD25+ Treg cells in chronic lung infection by Pseudomonas aeruginosa

Objective To explore the role of CD4+CD25+ Treg cells in chronic pulmonary infection caused by Pseudomonas aeruginosa(PA).Methods Sixty SD rats were randomly divided into a PA group and a control group(n=30 in each group).Chronic lung infection model was established by implantation of silicone tube precoated with PA into the main bronchus.Twenty-eight days later Treg cells in peripheral blood were measured by fluorescence-activated cell sorting（FACS）.Levels of IL-10 and TGF-β in serum were assayed by ELISA.The expression of Foxp3 mRNA in spleen was measured by RT-PCR.Pathological changes of lung tissue were studed by HE staining.Results Treg/CD4+ T cells in the PA group were significantly more than those in the control group[（19.79±6.45）% vs （5.15±0.47）%，Plt;0.05].The levels of IL-10 and TGF-β were (231.52±54.48)pg/mL and （121.05±7.98）pg/mL in the PA group respectively，which were significantly higher than those in the control group[（35.43±23.56）pg/mL and （36.02±8.94）pg/mL].The expression of Foxp3 mRNA in the PA group was significantly higher compared with the control group(0.80±0.044 vs 0.25±0.054，Plt;0.05）.HE staining revealed that PA caused a intensive inflammatory reaction with lymphocytes infiltration.Conclusion CD4+CD25+ Treg cell is up-regulated and plays an important role in chronic lung infection caused by Pseudomonas aeruginosa.

Study on Newborn Pneumonia of Pseudomonas Aeruginosa

摘要:目的:探讨新生儿铜绿假单胞菌肺炎的临床特点及药敏特点,为合理治疗提供依据。方法:对我院新生儿科2006年8月到2008年7月收治新生儿肺炎痰标本进行培养分离鉴定,选择培养结果为铜绿假单胞菌者做药敏及临床分析。结果:铜绿假单胞菌对碳青霉烯类,如:亚胺培南,美洛培南敏感率达100%,对近几年在新生儿较少用的或不用的氨基糖甙类,环丙沙星敏感率为85%～100%,而对常用的氨苄西林+舒巴坦不敏感,对头孢他啶敏感率gt;70%,临床根据药敏结果选择敏感抗生素治疗,疗效满意。结论:近年新生儿铜绿假单胞菌肺炎有上升趋势,病死率极高,故应根据药敏试验结果选择敏感抗生素,以控制疾病发展,降低病死率。

Predictors for carbapenem-resistant bacteria as the pathogens of bloodstream infections

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.

QRDR Mutations in Fluoroquinolon-Resistant Pseudomonas aeruginosa and Its Relationship with the Usage of Antibiotics in Nosocomial Pneumonia

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.