Nosocomial Infections in Nonsurgical Patients Undergoing Extracorporeal Membrane Oxygenation: A Retrospective Analysis in a Chinese Hospital.

Background: The effect of nosocomial infections (NIs) in adult patients undergoing ECMO has been rarely reported in China. Moreover, the effect of NIs on ECMO patients' mortality is still unclear and inconclusive according to literature data. In this study, we examined the prevalence, risk factors, causative organisms, and effects on outcomes of NIs in ECMO patients. Methods: A total of 79 nonsurgical patients (mean age 53.3±15.2 year (yr); 66% male) who underwent ECMO between January 2011 and September 2020 were enrolled in this retrospective study. Patients' demographic and clinical data and ECMO parameters were collected from all patients. Results: Among 79 patients who underwent ECMO for a total of 1253 ECMO days (mean time 15.9±14.1 d), 42 developed NIs. We observed 30 ventilator-associated pneumonia (VAP), 19 bloodstream infections (BSIs), and 4 urinary tract infections, corresponding to 23.9/1000 ECMO days, 15.2/1000 ECMO days, and 3.2/1000 ECMO days, respectively. ECMO duration (22.0±16.5 VS 8.9±5.3 d, P < 0.001), invasive mechanical ventilation (IMV) duration (27.4±20.5 VS 11.4±10.1 d, P < 0001), and ICU length of stay (35.9±22.9 VS 15.7±9.2 d, P < 0.001) were longer in patients with NIs. The independent risk factors for NIs were ECMO duration (Odds Ratio [OR], 1.414; 95% Confidence Interval [CI], (1.051-1.238); P = 0.002) and viral pneumonia (OR, 5.788; 95% CI, (1.551-21.596); P = 0.009). Gram-negative bacteria were the most common causative organisms of NIs; Acinetobacter baumannii (A. baumannii), Klebsiella pneumoniae (K. pneumoniae), and Pseudomonas aeruginosa (P. aeruginosa) were the most common bacteria. BSI (OR, 8.106; 95% CI, (1.384-47.474); P = 0.02) was an independent predictor for mortality. Conclusion: NIs are common complications in patients during ECMO treatment, especially VAP, followed by BSI. Also, BSI can negatively affect the survival rate.

Amino-Functionalized Polystyrene Nano-Plastics Induce Mitochondria Damage in Human Umbilical Vein Endothelial Cells.

As emerging contaminants, nano-plastics have become a major cause for concern for their adverse effects on the ecosystem and human health. The nano-sized properties of nano-plastics enable their exposure risks to humans through the food chain or other ways. However, the fate and adverse impact of nano-plastics on the human cardiovascular system are lacking. In this regard, the human umbilical vein endothelial cell line HUVEC was applied as a cell model to investigate the biological effects of noncharged polystyrene nano-plastics (PS NPs) and amino-functionalized nano-plastics (NH2-PS NPs). The positively charged PS NPs exhibited higher cytotoxicity to HUVEC, as evidenced by the decreased cell viability, enhanced ROS generation, and decreased mitochondria membrane potential triggered by NH2-PS NPs. Importantly, RT-PCR analysis revealed that NH2-PS NPs dysregulated the mitochondrial dynamics, replication, and function-related gene expression. This study demonstrated that NH2-PS NPs presented higher risks to endothelial cells than non-charged nano-plastics by interfering with mitochondria, which supported the direct evidence and expanded the potential risks of PS NPs.

Emergence of transferable ceftazidime-avibactam resistance in KPC-producing Klebsiella pneumoniae due to a novel CMY AmpC ß-lactamase in China.

OBJECTIVES: To evaluate the molecular mechanisms of ceftazidime/avibactam (CAZ/AVI) resistance in six Klebsiella pneumoniae strains that co-produce K. pneumoniae carbapenemase (KPC)-2 and a novel variant of CMY cephalosporinase in a Chinese hospital. METHODS: Antimicrobial susceptibility was determined by broth microdilution. Whole-genome sequencing (WGS) was performed to investigate potential resistance determinants. Plasmid conjugation, electroporation, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) hybridization and cloning experiment were carried out to investigate the resistance plasmids and genes. RESULTS: A high level of CAZ/AVI resistance was observed in six KPC-Kp strains (MIC 128 mg/L). Five strains were isolated in 2015 and one in 2016, before the approval of CAZ/AVI in China. Sequence analysis indicated that all the strains belonged to sequence type (ST) 11 and uniformly carried a novel CMY AmpC ß-lactamase gene, designated blaCMY-172. When compared with CMY-2, CMY-172 has a deletion of three consecutive amino acids (K290, V291 and A292) in the R2-loop region and a non-synonymous amino acid substitution at position 346 (N346I). The blaCMY-172-bearing plasmid, pKPCZA02_4, was 93.3 Kb, IncI1-I type, and conjugative; blaCMY-172 was located in an IS1294-mediated transposon. Plasmid conjugation and DNA fragment cloning proved that blaCMY-172 was responsible for CAZ/AVI resistance. CONCLUSIONS: Our study identified conjugative plasmid-mediated blaCMY-172 as a new mechanism for CAZ/AVI resistance in clinical KPC-Kp strains. Careful monitoring of CAZ/AVI susceptibility is imperative for preventing the spread of the resistance gene.

Safety and efficacy of anti-PD-1 inhibitors in Chinese patients with advanced lung cancer and hepatitis B virus infection: a retrospective single-center study.

BACKGROUND: Programmed death protein (ligand) 1 [PD-(L)1] inhibitors have provided new therapeutic options for advanced lung cancer. However, patients with hepatitis B virus (HBV) infection have been traditionally excluded from most registered trials of this form of treatment. METHODS: We performed a retrospective analysis of patients with HBV and advanced lung cancer who received anti-PD-1 immunotherapy from September 2018 to May 2020 in our department. Treatment-related hepatotoxicity was evaluated and recorded. Overall response rate and progression free survival were also assessed in the patients using iRECIST. RESULTS: Seventeen patients were evaluated in this analysis. Of these, six (35.3%) experienced hepatic transaminase elevation during immunotherapy. Three of these patients developed Grade 3 hepatic immune-related adverse events and received systemic corticosteroids, following which aminotransferase levels recovered to normal in all patients and no adverse events were observed in subsequent treatment. No patient experienced HBV reactivation or flare. One patient developed active pulmonary tuberculosis (TB). Other adverse events were mild, well tolerated and short term. The objective response rate (ORR) of the cohort was 62.5%, and the median progression-free survival (PFS) was 3 months. CONCLUSIONS: Lung cancer patients can be treated safely with anti-PD-1 inhibitors in the context of HBV infection. Close monitoring for hepatotoxicity and prophylactic antiviral therapy is advised. Further studies on the use of anti-PD-1 inhibitors in HBV-infected patients are needed.

Secondary Bacterial Infections in Critical Ill Patients With Coronavirus Disease 2019.

Secondary bacterial infections occurred in 13.9% (5 of 36) of critical ill patients with coronavirus disease 2019. All 5 patients had been admitted to intensive care unit and received mechanical ventilation before developing bacterial infection. Active surveillance of culture should be performed for critically ill patients. Prevention of nosocomial infection should to be taken seriously.

Microbiological and clinical characteristics of cryptococcemia: a retrospective analysis of 85 cases in a Chinese hospital.

Cryptococcemia is a life-threatening fungal infection. Sometimes, it is hard to diagnose. The studies to describe the characteristics of cryptococcemia specifically were limited. We performed this retrospective analysis in a Chinese hospital during 2002-2015, including 85 cryptococcemia cases and 52 Cryptococcus spp. isolates. The species, mating type, antifungal susceptibility and multilocus sequence typing of Cryptococcus spp. were determined. C. neoformans var. grubii MATα of sequence type (ST) 5 is the representative strain of cryptococcemia, accounting for 51 isolates. The MIC50/90 values were 0.5/0.5, 1.0/1.0, 2.0/4.0, ≤0.06/0.25, and ≤0.06/≤0.06 µg/ml for amphotericin B, flucytosine, fluconazole, itraconazole, and voriconazole, respectively. Cryptococcemia was the first diagnostic proof of cryptococcosis in 37 patients (43.5%, 37/85). Compared with the patients initially diagnosed of cryptococcosis in other sites (mainly cerebrospinal fluid), the patients firstly diagnosed by blood culture had prolonged time from admission to diagnosis of cryptococcosis (9 days vs. 2 days, P < .001) and higher 30-day mortality (54.1% vs. 20.8%, P = .003), while fewer symptoms of meningitis (45.9% vs. 100%, P < .001). For the patients receiving lumbar puncture, the occurrence of meningitis was similar between the patients firstly diagnosed by blood culture and those firstly diagnosed in other sites (94.1% vs. 100%, P = .26). However, the patients first diagnosed by blood culture had lower baseline intracranial pressure (250 mm H2O vs. 342.5 mm H2O, P = .001). In conclusion, patients with cryptococcemia as the first diagnostic proof of cryptococcosis usually had neglected subtle symptoms of meningitis, which may result in delayed diagnosis and catastrophic outcome.

High prevalence of KPC-2-producing hypervirulent Klebsiella pneumoniae causing meningitis in Eastern China.

BACKGROUND: Klebsiella pneumoniae has been the leading causative pathogen for adult bacterial meningitis in several Asian countries. The clinical and microbiological characteristics of K. pneumoniae meningitis in mainland China are still unknown. MATERIALS AND METHODS: The clinical data of patients with K. pneumoniae meningitis from January 2011 to July 2017 in a tertiary hospital were retrospectively evaluated. The isolates were tested for antibiotic-resistance genes, virulence-associated genes, and molecular subtypes. Hyper-virulent K. pneumoniae (hvKP) was defined as the presence of pLVPK-like virulence plasmid. RESULTS: During the study period, a total of 48 patients with meningitis caused by K. pneumoniae were identified, accounting for 21.2% (48/226) of Gram-negative bacilli meningitis. Of the 44 available isolates, 65.9% (29/44) were carbapenem resistant, and all except one har-bored bla KPC-2. K64 was the most common serotype (n=13), followed by K47 (n=11) and K1 (n=5). The pLVPK-related genetic loci were found in about half of isolates (iutA: 56.8%, iucA: 56.8%, rmpA2:50.0%, rmpA: 43.2%, and iroN: 40.9%). Twenty-two strains carrying pLVPK-derived virulence plasmid were defined as hvKP. Notably, the coexistence of bla KPC-2-encoding plasmid and the pLVPK-derived virulence plasmid was detected in 15 strains (34.1%, 15/44), suggesting K. pneumoniae carbapenemase-2 (KPC-2)-producing hvKP. The proportion of KPC-2-producing hvKP by year increased remarkably from 0% (2011) to 71.4% (2017). Of the 15 KPC-2-producing hvKP strains, 80.0% (12/15) were assigned to sequence type 11 and 2 strains (13.3%) belonged to clonal complex 23. Most of the patients infected with KPC-2-producing hvKP had preceding postneurosurgical state (93.3%, 14/15) and severe pneumonia (73.3%, 11/15). All the cases (100%, 15/15) had fatal outcome. CONCLUSION: The high prevalence and mortality of K. pneumoniae, especially KPC-2-producing hvKP meningitis, in China should be of concern. The implementation of epidemiological surveillance and identification of an effective clinical treatment are paramount.

Risk factors for acquisition and mortality of multidrug-resistant Acinetobacter baumannii bacteremia: A retrospective study from a Chinese hospital.

Bloodstream infection caused by Acinetobacter baumannii has become a major clinical concern, especially multidrug-resistant A baumannii (MDRAB). The aim of this study was to identify the risk factors of nosocomial acquired MDRAB bacteremia and to determine the risk factors related to the mortality of patients with MDRAB bacteremia. Patients with nosocomial acquired A baumannii bacteremia were enrolled between January, 2013 and December, 2017 at the First Affiliated Hospital, School of Medicine, Zhejiang University. Medical records were reviewed, and the clinical and microbial characteristics were collected. Among the 338 patients suffering from A baumannii bacteremia, 274 patients were infected with MDRAB bacteremia. Bacteremia-related mortality was 46.4% for the overall sample; 56.2% for MDRAB bacteremia patients, 4.7% for non-MDRAB bacteremia patients. The identified risk factors for developing MDRAB bacteremia were previous exposure to carbapenems [odds ratio (OR) 5.78, P = .005] and penicillins+ß-lactamase inhibitors (OR 4.29, P = .009). Primary bacteremia tended to develop non-MDR bacteremia (OR 0.10, P = .002). The risk factors for MDRAB bacteremia-related mortality were old age (OR 1.02, P = .036), a high Pitt bacteremia score (OR 1.32, P < .001), bacteremia occurring after severe pneumonia (OR 8.66, P < .001), while catheter-related infection (OR 0.47, P = .049) and operations for treating infection (OR 0.51, P = .043) may have a better outcome. Patients with MDRAB had a higher mortality rate. Patients with previous carbapenems and penicillins+ß-lactamase inhibitor exposure are at an increased risk of MDRAB bacteremia, whereas patients with primary bacteremia tended to develop non-MDR bacteremia. The risk factors for MDRAB bacteremia-related mortality were old age, a high Pitt bacteremia score, and bacteremia occurring after severe pneumonia, whereas catheter-related infection and operations for the treatment of infection may have a better outcome.

Virulence and genomic features of a bla CTX-M-3 and bla CTX-M-14 coharboring hypermucoviscous Klebsiella pneumoniae of serotype K2 and ST65.

BACKGROUND: Capsular serotype K2 Klebsiella pneumoniae of sequence type (ST) 65 has been recognized as a hypervirulent clone. Simultaneous presence of different bla CTX-M genes has never been reported in this clone. In the present study, the genetic characteristics and virulence phenotype of a CTX-M-3 and CTX-M-14 coproducing ST65 K. pneumoniae human isolate, KP_06, that caused an intracranial infection, are evaluated. METHODS: The potential virulence of KP_06 was assayed by in vitro and in vivo methods. The molecular biology and whole-genome sequencing technology were used to analyze the genomic features associated with the virulence of this strain. RESULTS: The KP_06 exhibited typical features of hypervirulent K. pneumoniae (hvKP), showing hypermucoviscosity phenotype and belonging to K2 and ST65. Apart from virulence genes linked to hvKP, including rmpA, rmpA2, and clb cluster and genes encoding siderophores, it was found to harbor a ~170 kb pLVPK-like virulence plasmid. In contrast to most hvKP, KP_06 was resistant to cephalosporins and the coexistence of bla CTX-M-3 and bla CTX-M-14 was detected. Further experiments demonstrated that this strain was classified as a nonbiofilm producer and serum sensitivity (grade 1) and killed only 30% of Galleria mellonella inoculated with 1×106 colony-forming unit of the specimen within 48 hours, suggesting relatively low virulence. Comparative genomic analysis of KP_06 with five K2 hypermucoviscous K. pneumoniae (HMKP) revealed seven unique orthologies with varied function in this strain. Intriguingly, the virulence genes identified in KP-06 were unexpectedly more diverse than those observed in five other K2 HMKP strains. CONCLUSION: Our data support the notion that neither virulence-associated genes (clusters) nor the pLVPK-like virulence plasmid is sufficient for the hypervirulence of K. pneumoniae. Future studies aiming to explore the virulence of K. pneumoniae should take genome-based profile together with experimental work. The detailed mechanism involving in the impaired virulence of KP_06 remains to be further explored.

Endogenous endophthalmitis caused by a multidrug-resistant hypervirulent Klebsiella pneumoniae strain belonging to a novel single locus variant of ST23: first case report in China.

BACKGROUND: Endogenous endophthalmitis caused by hypervirulent Klebsiella pneumoniae (HVKP) is an emerging infectious disease commonly with a devastating visual outcome. Most HVKP strains display a wild-type susceptibility profile to antibiotics. However, reports of antimicrobial-resistant HVKP have increased over time, which poses a serious therapeutic dilemma. CASE PRESENTATION: A 25-year-old man with a liver abscess and poorly controlled diabetes mellitus was admitted for endophthalmitis due to K. pneumoniae. The isolate displayed hypermucoviscosity as determined by a positive string test and exhibited resistance to ceftazidime, piperacillin-tazobactam and amikacin. Whole genome sequencing (WGS) analysis demonstrated the isolate to be a K1-serotype strain and belong to a novel single locus variant of ST23, ST2922. In addition to the virulence genes linked to HVKP, rmpA, magA, iucABCDiutA (aerobactin), ybtAPSTUX (yersiniabactin) and iroBDN (salmochelin), it was found to harbor extended-spectrum ß-lactamase (ESBL) gene (blaCTX-M-14), AmpC ß-lactamase gene (blaDHA), and 16S rRNA methylase gene (armA). CONCLUSIONS: This is the first known case of endogenous endophthalmitis caused by a multidrug-resistant HVKP strain ever reported in China. Early diagnosis and treatment with intravenous and intravitreal injection of carbapenem were essential for a favorable visual outcome.

Evaluation of a quantitative serum Aspergillus fumigatus-specific IgM assay for diagnosis of chronic pulmonary aspergillosis.

BACKGROUND: The early diagnosis of chronic pulmonary aspergillosis (CPA) remains challenging. Currently, a new quantitative IgM antibody assay that enveloped purified galactomannan extracted from Aspergillus fumigatus as antigen was commercially available in China, but its diagnostic value remains to be established. METHODS: To evaluate the role of this commercial IgM assay for diagnosis of CPA, a multi-center prospective study was performed in 12 hospitals in Zhejiang Province, from January 1 to December 31, 2016. Adult inpatients without severe immunocompromised condition and those with persistent clinical symptoms/radiological findings ≥3 months or a consistent appearance in chest CT that was suggestive of CPA were included. The clinical data were compiled using a structured questionnaire. RESULTS: A total of 87 cases were enrolled, including 43 CPA. The sensitivity ranged from 16.3% to 46.5%, and the specificity from 77.3% to 95.5% when cutoffs were from 50 to 80 arbitrary unit (AU)/mL. The receiver operating characteristic analysis revealed an area under the curve of 0.627. When a cutoff of 38.12 AU/mL was applied, the sensitivity and specificity were 69.8% and 56.8%, respectively, which represents the best performance. CONCLUSIONS: To our knowledge, this study was the first to evaluate this commercial A. fumigatus-specific IgM antibody assay in CPA patients in China and indicates that this IgM assay has a limited value and should not be a prior recommendation for CPA diagnosis.

Bloodstream infections caused by Klebsiella pneumoniae: prevalence of blaKPC, virulence factors and their impacts on clinical outcome.

BACKGROUND: Klebsiella pneumoniae bloodstream infections (BSIs) occur with significant prevalence and high mortality worldwide. Antimicrobial resistance and virulence are two main factors participating in the pathogenicity of K. pneumoniae. Here we investigated the prevalence of blaKPC and virulence factors in K. pneumoniae isolated from patients with BSIs and their association with clinical outcome. METHODS: The clinical data of 285 K. pneumoniae BSI cases diagnosed from January 2013 to December 2015 in a Chinese university hospital were retrospectively evaluated. The "string test" was performed to identify hypermucoviscous K. pneumoniae (HMKP). blaKPC, rmpA, magA and serotype-specific genes were detected by PCR amplification. Finally, a Cox proportional hazards model was employed to determine the predictors of 14-day mortality. RESULTS: Of these isolates, the prevalence of blaKPC and rmpA were 33.3% (95/285) and 31.6% (90/285) respectively. 69 isolates (24.2%, 69/285) were HMKP. rmpA was strongly associated with HM phenotype. The KPC-producing KP and HMKP were almost non-overlapping and only three HMKP isolates harbored blaKPC. K1 (28, 40.6%) and K2 (22, 31.9%) were the most common serotypes in HMKP. 44.9% of HMKP BSIs had origin of biliary tract infection or liver abscess. The 14-day mortality was 100% in blaKPC+/HM+ subgroup (3/3), followed by blaKPC+/HM- (39/92, 42.4%), blaKPC-/HM+ (5/66, 7.6%) and blaKPC-/HM- (7/124, 5.6%). The 14-day cumulative survival was significantly different between blaKPC+ and blaKPC- subgroup (Log-rank p < 0.001) but almost equal between blaKPC-/HM+ and blaKPC-/HM- subgroup (Log-rank p = 0.578) under the condition of comparable illness severity between blaKPC-/HM+ and blaKPC-/HM- subgroup. Independent risk factors for 14-day mortality were Pitt bacteremia score (HR 1.24, CI 95% 1.13-1.36, p < 0.001), Charlson comorbidity index (HR 1.24, CI 95% 1.09-1.41, p = 0.001), septic shock (HR 2.61, CI 95% 1.28-5.35, p = 0.009) and blaKPC (HR 2.20, CI 95% 1.06-4.54, p = 0.034). CONCLUSIONS: Most of HMKP were antibiotic-susceptible and people infected received appropriate antimicrobial therapy, which may explain the favorable outcome of HMKP BSIs. The KPC-producing HMKP BSIs were scarce but life-threatening. blaKPC was valuable in predicting 14-day mortality.

Evaluation of a commercial quantitative Aspergillus fumigatus-specific IgM assay for the diagnosis of invasive pulmonary aspergillosis.

Invasive pulmonary aspergillosis (IPA) is a common fungal infection with high mortality rates in immunocompromised patients. Early diagnosis of IPA is still challenging because of its nonspecific clinical symptoms and radiological presentations.To evaluate the clinical value of a commercial Aspergillus fumigates-specific IgM antibody assay in diagnosis of IPA, a multicenter prospective study was performed in 12 hospitals in Zhejiang Province, China, from January 1 to December 31, 2016.A total of 59 patients were enrolled in this study, including 30 IPA and 29 non-IPA patients. The sensitivities of IgM assay were 30.0%, 26.7%, 23.3%, and 20.0%, and the specificities were 79.3%, 86.2%, 86.2%, and 96.6% at the cutoff values of 50, 60, 70 and 80 AU/mL, respectively. The area under the curve of the IgM assay revealed by the receiver-operating characteristic analysis was 0.511 in the IPA cases. This study is the first to evaluate the clinical performance of a commercial A. fumigatus-specific IgM antibody assay that uses envelopes galactomannan extracted from A. fumigatus as the sole antigen in diagnosis of IPA.In conclusion, the A. fumigatus-specific IgM antibody assay has limited value and should not be a prior recommendation for IPA diagnosis.

Combination of Tigecycline and Levofloxacin for Successful Treatment of Nosocomial Pneumonia Caused by New Delhi Metallo-ß-Lactamase-1-Producing Raoultella planticola.

Raoultella planticola is a gram-negative bacterium that rarely causes diseases in humans. Here, we present a case of hospital-acquired pneumonia caused by R. planticola that likely originated in the gastrointestinal tract. To the best of our knowledge, this is the second report describing the detection of the gene New Delhi Metallo-ß-lactamase-1 (blaNDM-1) in multidrug-resistant R. planticola. Clinical samples were collected for bacterial culture and antimicrobial susceptibility testing from a patient during hospitalization. The presence of blaNDM-1 was detected by PCR and sequencing. An NDM-1-positive R. planticola was isolated from the sputum and stool of the same patient. Further findings confirmed that blaNDM-1 was located on a plasmid. Isolates from the sputum and stool cultures were identical, suggesting that the R. planticola may have originated in the gastrointestinal tract. The patient completely recovered and was discharged after treatment with tigecycline combined with levofloxacin, for a week. In conclusion, R. planticola is a possibly underestimated pathogen that contributes to the spread of the blaNDM-1 gene. Early and precise identification of this pathogen can lead to better prognosis of the associated infections and an improved approach to controlling the spread of carbapenemase-resistant gram-negative bacteria.

Diagnostic accuracy of a novel lateral-flow device in invasive aspergillosis: a meta-analysis.

A novel lateral-flow device (LFD) has been invented for use as a diagnostic tool for invasive aspergillosis (IA). We conducted a meta-analysis to assess the diagnostic accuracy of the device. Published studies that used the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria and provided sufficient data were included. Two reviewers independently collected the data from each study and assessed the risk bias using the Quality Assessment of Diagnostic Accuracy Studies-2. The pooled sensitivity, specificity and diagnostic odds ratio (DOR) were computed and reported with a 95  % confidence interval (CI). Seven studies published between 2008 and March 2015 were included. The pooled sensitivity, specificity and DOR for the proven/probable versus no IA cases were 0.86 (95  % CI, 0.76-0.93), 0.93 (95  % CI, 0.89-0.96) and 65.94 (95  % CI, 27.21-159.81) in the LFD test using bronchoalveolar lavage (BAL) fluid, and 0.68 (95  % CI, 0.52-0.81), 0.87 (95  % CI, 0.80-0.92) and 11.90 (95  % CI, 3.54-39.96) in the LFD test using serum. We concluded that the Aspergillus LFD had a good diagnostic value in immunocompromised patients at risk of IA. The BAL LFD might have a better performance than the serum LFD test.

Dissemination of blaOXA-23 in Acinetobacter spp. in China: main roles of conjugative plasmid pAZJ221 and transposon Tn2009.

Production of the OXA-23 carbapenemase is the most common reason for the increasing carbapenem resistance in Acinetobacter spp. This study was conducted to reveal the genetic basis of blaOXA-23 dissemination in Acinetobacter spp. in China. A total of 63 carbapenem-resistant OXA-23-producing Acinetobacter sp. isolates, representing different backgrounds, were selected from 28 hospitals in 18 provinces for this study. Generally, two patterns of plasmids carrying blaOXA-23 were detected according to S1-nuclease pulsed-field gel electrophoresis and Southern blot hybridization. A ca. 78-kb plasmid, designated pAZJ221, was found in 23 Acinetobacter baumannii and three Acinetobacter nosocomialis isolates, while a novel ca. 50-kb plasmid was carried by only two other A. baumannii isolates. Three of these isolates had an additional copy of blaOXA-23 on the chromosome. Transformation of the two plasmids succeeded, but only pAZJ221 was conjugative. Plasmid pAZJ221 was sequenced completely and found to carry no previously known resistance genes except blaOXA-23. The blaOXA-23 gene of the remaining 35 isolates was chromosome borne. The blaOXA-23 genetic environments were correlated with Tn2009 in 57 isolates, Tn2008 in 5 isolates, and Tn2006 in 1 isolate. The MIC values for the carbapenems with these isolates were not significantly associated with the genomic locations or the copy numbers of blaOXA-23. Overall, these observations suggest that the plasmid pAZJ221 and Tn2009 have effectively contributed to the wide dissemination of blaOXA-23 in Acinetobacter spp. in China and that horizontal gene transfer may play an important role in dissemination of the blaOXA-23 gene.

Characterization of a novel plasmid type and various genetic contexts of bla OXA-58 in Acinetobacter spp. from multiple cities in China.

BACKGROUND/OBJECTIVE: Several studies have described the epidemiological distribution of blaOXA-58-harboring Acinetobacter baumannii in China. However, there is limited data concerning the replicon types of blaOXA-58-carrying plasmids and the genetic context surrounding blaOXA-58 in Acinetobacter spp. in China. METHODOLOGY/PRINCIPAL FINDINGS: Twelve non-duplicated blaOXA-58-harboring Acinetobacter spp. isolates were collected from six hospitals in five different cities between 2005 and 2010. The molecular epidemiology of the isolates was carried out using PFGE and multilocus sequence typing. Carbapenemase-encoding genes and plasmid replicase genes were identified by PCR. The genetic location of blaOXA-58 was analyzed using S1-nuclease method. Plasmid conjugation and electrotransformation were performed to evaluate the transferability of blaOXA-58-harboring plasmids. The genetic structure surrounding blaOXA-58 was determined by cloning experiments. The twelve isolates included two Acinetobacter pittii isolates (belong to one pulsotype), three Acinetobacter nosocomialis isolates (belong to two pulsotypes) and seven Acinetobacter baumannii isolates (belong to two pulsotypes/sequence types). A. baumannii ST91 was found to be a potential multidrug resistant risk clone carrying both blaOXA-58 and blaOXA-23. blaOXA-58 located on plasmids varied from ca. 52 kb to ca. 143 kb. All plasmids can be electrotransformed to A. baumannii recipient, but were untypeable by the current replicon typing scheme. A novel plasmid replicase named repAci10 was identified in blaOXA-58-harboring plasmids of two A. pittii isolates, three A. nosocomialis isolates and two A. baumannii isolates. Four kinds of genetic contexts of blaOXA-58 were identified. The transformants of plasmids with structure of IS6 family insertion sequence (ISOur1, IS1008 or IS15)-ΔISAba3-like element-blaOXA-58 displayed carbapenem nonsusceptible, while others with structure of intact ISAba3-like element-blaOXA-58 were carbapenem susceptible. CONCLUSION: The study revealed the unique features of blaOXA-58-carrying plasmids in Acinetobacter spp. in China, which were different from that of Acinetobacter spp. found in European countries. The diversity of the genetic contexts of blaOXA-58 contributed to various antibiotics resistance profiles.

Changes of fecal Bifidobacterium species in adult patients with hepatitis B virus-induced chronic liver disease.

The beneficial effects of Bifidobacteria on health have been widely accepted. Patients with chronic liver disease have varying degrees of intestinal microflora imbalance with a decrease of total Bifidobacterial counts. Since different properties have been attributed to different Bifidobacterium species and there is no information available for the detailed changes in the genus Bifidobacterium in patients with chronic liver disease heretofore, it is meaningful to investigate the structure of this bacterium at the species level in these patients. The aim of this study was to characterize the composition of intestinal Bifidobacterium in patients with hepatitis B virus-induced chronic liver disease. Nested-PCR-based denaturing gradient gel electrophoresis (PCR-DGGE), clone library, and real-time quantitative PCR were performed on the fecal samples of 16 patients with chronic hepatitis B (CHB patients), 16 patients with hepatitis B virus-related cirrhosis (HBV cirrhotics), and 15 healthy subjects (Controls). Though there was no significant difference in the diversity among the three groups (P = 0.196), Bifidobacterium dentium seems to be specifically enhanced in patients as the PCR-DGGE profiles showed, which was further validated by clone library and real-time quantitative PCR. In contrast to the B. dentium, Bifidobacterium catenulatum/Bifidobacterium pseudocatenulatum were detected less frequently in the predominant profile and by quantitative PCR in HBV cirrhotics than in the controls, and the level of this species was also significantly different between these two groups (P = 0.023). Although having no quantitative difference among the three groups, Bifidobacterium longum was less commonly detected in HBV cirrhotics than in CHB patients and Controls by quantitative PCR (P = 0.011). Thus, the composition of intestinal Bifidobacterium was deeply altered in CHB and HBV cirrhotic patients with a shift from beneficial species to opportunistic pathogens. The results provide further insights into the dysbiosis of the intestinal microbiota in patients with hepatitis B virus-induced chronic liver disease and might potentially serve as guidance for the probiotics interventions of these diseases.

Clinical carbapenem-resistant Acinetobacter baylyi strain coharboring blaSIM-1 and blaOXA-23 from China.

bla(SIM-1) and bla(OXA-23) were codetected in clinical carbapenem-resistant Acinetobacter baylyi strain NB09A30. Both of carbapenemase genes were located on a large plasmid (ca. 360 kb). bla(SIM-1) was found as a gene cassette inserted into a class 1 integron identical to that determined in Acinetobacter sp. isolates from South Korea. The genetic structure of bla(OXA-23) in NB09A30 was different from that in the prevalent Acinetobacter baumannii of clonal complex 92 (CC92) from the same hospital.

Wide dissemination of OXA-23-producing carbapenem-resistant Acinetobacter baumannii clonal complex 22 in multiple cities of China.

OBJECTIVES: In this study, multilocus sequence typing (MLST) was used to describe the genetic backgrounds of carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-susceptible A. baumannii (CSAB) from multiple cities of China. METHODS: One hundred and fifty-two CRAB and 74 CSAB isolates obtained from 16 cities of China were selected for molecular characterization by MLST. eBURST was used to cluster sequence types (STs) into clonal complex (CCs) and infer evolutionary descent. PCR was used to detect carbapenemase-encoding genes and bla(AmpC) with the upstream element ISAba1. RESULTS: CSAB showed more diverse genetic backgrounds than CRAB since 36 distinct STs were identified in CSAB while only 8 STs were identified in CRAB. ST22 and its three single-locus variants, all clustered into CC22, were the most prominent STs, accounting for 86.8% of CRAB and 45.9% of CSAB, distributed in all 16 cities and possessing more noticeable antibiotic resistance than other STs. PCR amplification was positive for bla(OXA-23) in most CRAB isolates but negative in CSAB isolates. The presence of ISAba1 upstream of bla(AmpC) was variable in distinct STs of CRAB. eBURST reveals that CC22 is the largest group in the Pubmlst database, which also contains ST6 previously identified in a European clone II isolate as a member of a subgroup of CC22. CONCLUSIONS: We describe the wide dissemination of CRAB CC22 in China. The close relatedness between CC22 and European clone II implies the probable global spread of CC22. It is inferred that ST22-CSAB evolves to ST22-CRAB through acquiring bla(OXA-23) as a determinative factor.