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TMexCD1-TOprJ1, which is associated with phenotypic resistance to multiple classes of antibiotics, is a transmissible resistance-nodulation-division (RND) family efflux pump. However, the prevalence and genomic and phenotypic characteristics of clinical isolates with this important resistance determinant are poorly understood. In this study, we aimed to survey tmexCD-toprJ among clinical Gram-negative isolates collected from hospitals in China between 1991 and 2020 and characterise tmexCD-toprJ-positive clinical isolates.We conducted online data retrieval and active nationwide surveillance in China to screen tmexCD-toprJ-positive strains. We characterised tmexCD-toprJ-positive clinical strains for their antimicrobial susceptibility, genetic and functional characteristics, and the potential inter-species transmission route of tmexCD-toprJ with whole genome sequencing and bioinformatics analyses. The function of tmexCD-toprJ in Pseudomonas sp and Proteus sp was investigated by tmexD gene knockdown using an isopropylthio-β-galactoside-inducible CRISPR interference system.Data retrieval obtained 53 strains carrying tmexCD-toprJ, comprising 32 Pseudomonas spp, 11 Klebsiella pneumoniae, one Aeromonas spp, one Citrobacter freundii, and one uncultured bacterium from diverse niches. 48 (0·64%) of 7517 clinical isolates from China, including seven Klebsiella spp, one Proteus mirabilis, and 40 Pseudomonas spp, carried tmexCD-toprJ. These isolates exhibited multidrug resistance phenotypes and co-harboured resistance genes, such as mcr and carbapenemases genes. tmexCD-toprJ was encoded on both plasmids and chromosomes in all Klebsiella spp that carried plasmid-borne tmexCD-toprJ (n=7), P mirabilis carried chromosome-borne tmexCD-toprJ, and Pseudomonas spp carried either plasmid-borne (n=19) or chromosome-borne (n=21) ones. tmexCD-toprJ had undergone clonal and horizontal transmission among clinical pathogens. Eight different types of genetic context of tmexCD-toprJ were identified, each of which was associated with different mobile elements, including IntI, IS6100, TnAs1-like, ISRor5, ISVsa3, ISCfr-like, Tn5393, and IS222-like, which might facilitate its transmission. Knockdown of tmexD led to a four times decrease in tigecycline minimum inhibitory concentrations in both Pseudomonas spp and Proteus spp.Our study provides evidence to suggest that tmexCD-toprJ contributes to the antimicrobial resistance phenotypes in different bacterial species. tmexCD-toprJ has disseminated among diverse species of clinical pathogens, which warrants timely monitoring in clinical pathogens.National Natural Science Foundation of China, Guangdong Major Project of Basic and Applied Basic Research, Natural Science Foundation of Jiangsu Province.

Objectives To investigate the molecular characteristics and transferability of plasmid-borne linezolid resistance genes optrA, cfr, poxtA2 and cfr(D) genes in one linezolid-resistant Enterococcus faecalis DM86 from retail meat. Methods E. faecalis DM86 was screened for the presence of known linezolid resistance genes via PCR analysis. Conjugation experiments were used to evaluate the transferability of the resistance genes. The complete genome of E. faecalis DM86 was obtained using both the Illumina and Nanopore platforms. Results Analysis of the complete sequence showed that E. faecalis DM86 belonged to sequence type 116 (ST116). Four linezolid resistance genes were identified on three plasmids, designated as pDM86-2-cfr, pDM86-3-optrA and pDM86-4-poxtA [cfr(D) co-located]. IS1216 mobile elements were found to flank the cfr and optrA locus on these two plasmids. pDM86-3-optrA encoded the RDK-type OptrA protein and a common genetic array of ‘IS1216-fexA-optrA-erm(A)-IS1216’ was identified on this plasmid. The cfr(D) gene was closely associated with the poxtA2 gene on pDM86-4-poxtA, and similar plasmids and structures were reported recently in the E. faecalis of animal origin. The intra- and inter-species horizontal transferability of this plasmid to E. faecalis JH2-2, Enterococcus faecium BM4105RF and Staphylococcus aureus RN4220 was also proved, with a frequency of 2.8 × 10−3, 1.7 × 10−3 and 3.4 × 10−5, respectively. Conclusions This was the first report of the co-existence of up to four plasmid-borne linezolid resistance genes in one E. faecalis. Thus, efficient actions should be exerted to circumvent the microbiota contamination of food and the further spread of these antimicrobial resistance reservoirs.

Background. Although the clinical features of Acinetobacter baumannii bloodstream infection are well described, the specific clinical characteristics of polymicrobial Acinetobacter baumannii bloodstream infection have been rarely reported. The objective of this study was to examine the risk factors for and clinical outcomes of polymicrobial Acinetobacter baumannii bloodstream infection. Methods. A retrospective observational study was performed from January 2013 to December 2018 in a tertiary hospital. All patients with Acinetobacter baumannii bloodstream infection were enrolled, and the data were collected from the electronic medical records. Results. A total of 594 patients were included, 21% (126/594) of whom had polymicrobial infection. The most common copathogen was Klebsiella pneumoniae (20.81%), followed by Pseudomonas aeruginosa (16.78%) and Enterococcus faecium (12.08%). Compared with monomicrobial Acinetobacter baumannii bloodstream infection, polymicrobial Acinetobacter baumannii bloodstream infection mostly originated from the skin and soft tissue (28.6% vs. 10.5%, p < 0.001 ). Multivariate analysis revealed that burn injury was independently associated with polymicrobial Acinetobacter baumannii bloodstream infection (adjusted odds ratio, 3.569; 95% confidence interval, 1.954-6.516). Patients with polymicrobial Acinetobacter baumannii bloodstream infection were more likely to have a longer hospital length of stay [40 (21, 68) vs. 27 (16, 45), p < 0.001 ] and more hospitalization days after bloodstream infection than those with monomicrobial Acinetobacter baumannii bloodstream infection [22 (8, 50) vs. 13 (4, 28), p < 0.001 ]. However, no significant difference in mortality was observed between the two groups. Conclusions. Approximately one-fifth of Acinetobacter baumannii bloodstream infections were polymicrobial in this cohort. The main sources were skin and soft tissue infections, and burn injury was the only independent risk factor. Although mortality did not differ between the groups, considering the limitations of the study, further studies are required to assess the impact of polymicrobial (vs. monomicrobial) Acinetobacter baumannii bloodstream infection on outcomes.

The multidrug resistance gene

Colistin is recognized as a last-resort treatment option against multi-drug resistant bacteria including carbapenem-resistant Enterobacteriaceae (CRE). However, the plasmid-mediated colistin-resistance gene mcr-1 has been reported globally resulting in an increase of colistin-resistant bacteria. A quick and accurate method for determining the pathogen resistance of colistin is therefore crucial in the clinic. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a potential tool forto be applied for antimicrobial susceptibility testing. We compared the growth of Escherichia coli strains in the presence or absence of colistin. Automated analyses of the spectra were performed with a prototype software tool written with package R. Three mcr-1-positive and six mcr-1-negative E. coli were used for establishing the model to obtain the optimal incubation time, the breakpoint concentration of colistin and cut-off of the relative growth (RG) value. The distinction between susceptible and resistant strains was already noticeable after 2 h of incubation. The best separation between the susceptible and resistant strains was achieved at a concentration of 4 µg ml-1 and a relative growth cut-off value of 0.6. Application of the model for the analysis of 128 E. coli isolates, a sensitivity of 97.4% and a specificity of 88.2% were achieved compared with colistin MIC results. The rapid MALDI-TOF MS-based method approach is simple to set-up, uses a short incubation time, and had excellent outcomes with respect to sensitivity and specificity for colistin sensitivity testing in Escherichia coli.

Dissemination of the

Emergence of tigecycline-resistance tet(X) gene orthologues rendered tigecycline ineffective as last-resort antibiotic. To understand the potential origin and transmission mechanisms of these genes, we survey the prevalence of tet(X) and its orthologues in 2997 clinical E. coli and K. pneumoniae isolates collected nationwide in China with results showing very low prevalence on these two types of strains, 0.32% and 0%, respectively. Further surveillance of tet(X) orthologues in 3692 different clinical Gram-negative bacterial strains collected during 1994–2019 in hospitals in Zhejiang province, China reveals 106 (2.7%) tet(X)-bearing strains with Flavobacteriaceae being the dominant (97/376, 25.8%) bacteria. In addition, tet(X)s are found to be predominantly located on the chromosomes of Flavobacteriaceae and share similar GC-content as Flavobacteriaceae. It also further evolves into different orthologues and transmits among different species. Data from this work suggest that Flavobacteriaceae could be the potential ancestral source of the tigecycline resistance gene tet(X)., Emergence of tigecycline-resistance tet(X) genes is of concern. Here, the authors determine tet(X) prevalence in more than 6,000 clinical Gram-negative bacterial isolates collected between 1994 to 2019 in hospitals in China and suggest that Flavobacteriaceae could be the potential ancestral source of the tigecycline resistance genes.

Purpose Although the enterococcal bloodstream infections (EBSI) are often observed in clinic, the mixed-EBSI are few reported. The aim of this study was to investigate the clinical characteristics and risk factors of mixed-EBSI in comparison with monomicrobial EBSI (mono-EBSI). Methods A single-center retrospective observational study was performed between Jan 1, 2013 and Dec 31, 2018 in a tertiary hospital. All patients with EBSI were enrolled, and their data were collected by reviewing electronic medical records. Results A total of 451 patients with EBSI were enrolled including 157 cases (34.8%) with mixed-EBSI. The most common co-pathogens were Coagulase-negative Staphylococcus (26.86%), followed by Acinetobacter baumannii (23.43%) and Klebsiella pneumoniae (8.57%). In multivariable analysis, burn injury (adjusted odds ratio [aOR], 7.39; 95% confidence interval [CI], 2.69-20.28), and length of prior hospital stay (aOR, 1.01; 95% CI, 1.00-1.02) were associated with mixed-EBSI. Patients with mixed-EBSI developed with more proportion of septic shock (19% vs. 31.8%, p=0.002), prolonged length of intensive care unit (ICU) stay [9(0,25) vs. 15(2.5,36), p

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) pneumonia (MP) and MRSA bloodstream infections (MRSA-BSI) are relatively often described, but MP with secondary MRSA-BSI (termed as MP-BSI) is few reported. Herein, we attempted to investigate the clinical features, risk factors and outcomes of MP-BSI in comparison with MP alone.MethodsClinical data from patients with MP was retrospectively collected. The cases were divided into groups of MP alone and MP-BSI. Determination of independent risk factors for MP-BSI relied on binomial logistic regression analysis. In addition, the outcomes were also compared.ResultsA total of 435 patients with MP were recruited, 18.9% (82/435) of whom was MP-BSI. The median age was 62 (interquartile range,51,72) years, and 74.5% were male. Multivariate analysis revealed that high SOFA score, immunosuppression, community-acquired MRSA pneumonia (CA-MP), time from initial to targeted antibiotics, accelerated respiratory rate, elevated γ-GT (all p

Although the clinical features ofA retrospective observational study was performed from January 2013 to December 2018 in a tertiary hospital. All patients withA total of 594 patients were included, 21% (126/594) of whom had polymicrobial infection. The most common copathogen wasApproximately one-fifth of

Three carbapenem-resistant Klebsiella pneumoniae (CRKP; strains KP-426, KP-C76, and KP-CT77) were isolated from a patient with severe burns during the treatment of colistin and tigecycline. Single-nucleotide polymorphism typing showed that three ST11 CRKP were clonally related. Three isolates harbored the same set of antimicrobial resistance genes. blaKPC-2, blaSHV-12, blaTEM-1, and rmtB genes were located on the same 128,928-bp IncFII/IncR plasmid. Tet(A), catA2, sul2, and dfrA14 genes were located on a plasmid with an unknown Inc-type. blaSHV-11, fosA, and aadA2 were chromosomal genes. An IS1 and an ISKpn14 were found in the promoter region of the mgrB gene of two colistin-resistant CRKP, K. pneumoniae KP-C76, and KP-CT77, respectively. A novel amino acid substitution, G300E, was identified in the type 1 Tet(A) variant of K. pneumoniae KP-CT77 which exhibited high-level tigecycline resistance compared to strains KP-426 and KP-C76 (MIC of 32, 4, and 4mg/l, respectively). Conjugation and cloning experiments confirmed that the mutated Tet(A) resulted in a 4-fold increase in tigecycline minimal inhibitory concentration (MIC) of Escherichia coli. Three CRKP belonged to the K64 serotype and possessed a similar IncHI1B/repB virulence plasmid carrying rmpA, rmpA2, and iucABCDiutA. The survival rates of Galleria Mellonella injected with K. pneumoniae KP-426, KP-C76, and KP-CT77 were 4.2, 20.8, and 8.3%, respectively. The emergence of colistin and tigecycline resistance in carbapenem-resistant hypervirulent K. pneumoniae posed a serious threat to clinical anti-infective therapy. The type 1 Tet(A) variant carrying G300E mutation, which conferred significantly elevated tigecycline MIC and was located on a conjugative plasmid, needs attention.

Fengqi Liu,1,2,&ast; Li Zhong,1,2,&ast; Feifei Zhou,3,&ast; Cheng Zheng,1,4 Kai Zhang,1 Jiachang Cai,5 Hongwei Zhou,5 Kankai Tang,2 Zhaohui Dong,2 Wei Cui,1 Gensheng Zhang1 1Department of Critical Care Medicine, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310009, People’s Republic of China; 2Department of Critical Care Medicine, First Affiliated Hospital, Huzhou Teachers College, The First People’s Hospital of Huzhou, Huzhou, 313000, Zhejiang, People’s Republic of China; 3Department of Critical Care Medicine, Ningbo Medical Center, Li Huili Hospital, Ningbo, Zhejiang, 315040, People’s Republic of China; 4Department of Critical Care Medicine, Taizhou Municipal Hospital, Taizhou, Zhejiang, 318000, People’s Republic of China; 5Department of Clinical Microbiology Laboratory, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Gensheng Zhang; Wei CuiDepartment of Critical Care Medicine, Second Affiliated Hospital, Zhejiang University School of Medicine, cc88 Jiefang Road, Hangzhou, 310009, People’s Republic of ChinaTel +86-571-8778-3636; +86-571-8778-3551Fax +86-571- 87022776Email genshengzhang@zju.edu.cn; zricu@zju.edu.cnPurpose: Candida albicans (C. albicans) candidemia has been well reported in previous studies, while research on non-albicans Candida (NAC) bloodstream infections remains poorly explored. Therefore, the present study aimed to investigate the clinical characteristics and outcomes of patients with NAC candidemia.Patients and Methods: We recruited inpatients with candidemia from January 2013 to June 2020 in a tertiary hospital for this retrospective observational study.Results: A total of 301 patients with candidemia were recruited in the current study, including 161 (53.5%) patients with NAC candidemia. The main pathogens in NAC candidemia were Candida tropicalis (C. tropicalis) (23.9%), Candida parapsilosis (15.6%) and Candida glabrata (10.3%). Patients with NAC candidemia had more medical admissions (P=0.034), a higher percentage of hematological malignancies (P=0.007), a higher frequency of antifungal exposure (P=0.012), and more indwelling peripherally inserted central catheters (P=0.002) than those with C. albicans candidemia. In a multivariable analysis, prior antifungal exposure was independently related to NAC candidemia (adjusted odds ratio [aOR], 0.312; 95% confidence interval [CI], 0.113– 0.859). Additionally, NAC was obviously resistant to azoles, especially C. tropicalis had a high cross-resistance to azoles. However, no significant differences were noted in the mortality rates at 14 days, 28 days and 60 days between these two groups.Conclusion: NAC is dominant in candidemia, and prior antifungal exposure is an independent risk factor. Of note, although the outcomes of NAC and C. albicans candidemia are similar, drug resistance to specific azoles as well as cross-resistance frequently occurs in patients with NAC candidemia, and this drug resistance deserves attention in clinical practice and further in-depth investigation.Keywords: non-albicans candidemia, clinical features, risk factor, cross-resistance

Neddylation, a posttranslational modification in which NEDD8 is covalently attached to target proteins, has emerged as an endogenous regulator of innate immunity. However, the role of neddylation in methicillin-resistant Staphylococcus aureus (MRSA) infection remains unknown. In this study, we found that neddylation was activated after MRSA infection in vivo and in vitro. Inhibition of neddylation with MLN4924 promoted injury of liver and kidneys in C57BL/6 mice with MRSA bloodstream infection and increased mortality. Blockade of neddylation, either pharmacologically (MLN4924, DI591) or through the use of Uba3 small interfering RNA, inhibited Cullin3 neddylation and promoted Nrf2 accumulation, thus reducing reactive oxygen species (ROS) induction and bacterial killing ability in mouse peritoneal macrophages. In summary, our findings suggest that activation of neddylation in macrophages plays a critical protective role against MRSA infection by increasing ROS production, partially by signaling through the NEDD8-Cullin3-Nrf2-ROS axis. Furthermore, our results may provide a new non-antibiotic treatment strategy for MRSA infection through targeting of neddylation.

The acquisition of resistance to one antibiotic sometimes leads to collateral sensitivity to a second antibiotic. Here, we show that vancomycin resistance in Enterococcus faecium is associated with a remarkable increase in susceptibility to pleuromutilin antibiotics (such as lefamulin), which target the bacterial ribosome. The trade-off between vancomycin and pleuromutilins is mediated by epistasis between the van gene cluster and msrC, encoding an ABC-F protein that protects bacterial ribosomes from antibiotic targeting. In mouse models of vancomycin-resistant E. faecium colonization and septicemia, pleuromutilin treatment reduces colonization and improves survival more effectively than standard therapy (linezolid). Our findings suggest that pleuromutilins may be useful for the treatment of vancomycin-resistant E. faecium infections.

Background Candida albicans (C. albicans) candidemia were well reported in previous studies, while researches on Candida non-albicans (C. non-albicans) candidemia remain poorly explored. Therefore the present study was aimed to investigate the clinical characteristics, and outcomes of C. non-albicans candidemia. Methods We recruited inpatients with candidemia from January 2013 to June 2020 in a tertiary hospital for this retrospective observational study. Results Total 301 patients with candidemia were recruited in current study, including 161 (53.5%) patients with C. non-albicans candidemia. The main pathogens in C. non-albicans candidemia were Candida tropicalis (23.9%), Candida parapsilosis (15.6%) and Candida glabrata (10.3%). Patients with C. non-albicans candidemia had more medical admissions (P = 0.034), more percentage of hematological malignancies (P = 0.007), more frequency of antifungal exposure (P = 0.012), and more indwelling peripherally inserted central catheter (P = 0.002) in comparison with C. albicans candidemia. In multivariable analysis, prior antifungal exposure was independently related to C. non-albicans candidemia (adjusted odds ratio [aOR], 0.312; 95% confidence interval [CI], 0.113–0.859). Additionally, C. non-albicans was obviously resistant to azoles, especially for C. tropicalis with a high cross-resistance to azoles. However, no significant differences were noted about the mortalities of 14 days, 28 days and 60 days between these two groups. Conclusions C. non-albicans are dominant in candidemia, and prior antifungal exposure is an independent risk factor. Of note, although outcomes between C. non-albicans and C. albicans candidemia are similar, the drug-resistance to specific azoles as well as cross-resistance frequently occurs in patients with C. non-albicans candidemia, which deserves attentions in clinical practice and further in-depth investigation.

Background: Although the clinical features of Acinetobacter baumannii bloodstream infection are well described, the specific clinical characteristics of mixed Acinetobacter baumannii bloodstream infection are rarely reported. The objective of this study was to examine the risk factors and clinical outcomes of mixed Acinetobacter baumannii bloodstream infection. Methods: A retrospectively observational study was performed from January 2013 to December 2018 in a tertiary hospital. All patients with Acinetobacter baumannii bloodstream infection were enrolled,the data were collected from electronic medical records. Results: A total of 594 episodes were enrolled, 21% (126/594) of which were mixed Acinetobacter baumannii bloodstream infection.The most common co-pathogens were Klebsiella pneumoniae (20.81%), followed by Pseudomonas aeruginosa (16.78%) and Enterococcus faecium (12.08%). Compared with monomicrobial Acinetobacter baumannii bloodstream infection, the main source of mixed Acinetobacter baumannii bloodstream infection was from skin and soft tissue(28.6% vs.10.5%, PConclusions: Mixed Acinetobacter baumannii bloodstream infection is not a rare event, which accounts for one fifth of all Acinetobacter baumannii bloodstream infection. The main source is from skin and soft tissue, and burn injury is an independent risk factor. Although the mortality is not different, patients with mixed Acinetobacter baumannii bloodstream infection might have poor outcomes, which merits more attention by physicians in the future.

Background Polymicrobial Klebsiella pneumoniae bloodstream infection (KP-BSI) has been reported to account for more than 10% of all KP-BSI, but few studies have characterized polymicrobial KP-BSI. Our study investigated the clinical characteristics, risk factors, and outcomes of polymicrobial KP-BSI by comparing with monomicrobial KP-BSI. Methods We conducted a single-center retrospective cohort study of patients with KP-BSI from 1 January 2013 to 31 December 2018 and collected the clinical data by reviewing electronic medical records. Results Of the 818 patients with KP-BSI recruited, 13.9% (114/818) were polymicrobial KP-BSI. The severity of illness in polymicrobial and monomicrobial KP-BSI was similar, while the rate of resistance to carbapenems was obviously higher in polymicrobial KP-BSI (78.1% vs. 65.6%, p = 0.009). On multivariate analysis, hospitalization in burn ward (odds ratio (OR) 6.13, 95% confidence interval (CI) 2.00-18.76, p = 0.001) and intensive care unit (OR 2.39, 95% CI 1.05-5.43, p = 0.038) was independently associated with polymicrobial KP-BSI. Gram-negative bacteria accounted for the highest proportion (68.9%) among copathogens of polymicrobial KP-BSI, whereas gram-positive bacteria (22.9%) and Candida (8.2%) ranked the second and the third, respectively, with Acinetobacter baumannii being the most common (23.0%). Patients with polymicrobial KP-BSI had longer hospital days after BSI onset and total hospital days than patients with monomicrobial KP-BSI (median (interquartile range (IQR)), 19 (5, 39) vs. 12 (6, 25), 37 (21, 67) vs. 29 (16, 53), respectively, p < 0.05). The mortality did not differ between polymicrobial KP-BSI and monomicrobial KP-BSI (all p > 0.05). Conclusions It was observed that polymicrobial KP-BSI accounted for a significant proportion among all KP-BSI in the current study. Hospitalization in burn ward and intensive care unit was an independent risk factor for the development of polymicrobial KP-BSI. The patients with polymicrobial KP-BSI had a higher rate of carbapenem-resistant K. pneumoniae and might have poor outcomes compared to monomicrobial KP-BSI.

Background. Polymicrobial Klebsiella pneumoniae bloodstream infection (KP-BSI) has been reported to account for more than 10% of all KP-BSI, but few studies have characterized polymicrobial KP-BSI. Our study investigated the clinical characteristics, risk factors, and outcomes of polymicrobial KP-BSI by comparing with monomicrobial KP-BSI. Methods. We conducted a single-center retrospective cohort study of patients with KP-BSI from 1 January 2013 to 31 December 2018 and collected the clinical data by reviewing electronic medical records. Results. Of the 818 patients with KP-BSI recruited, 13.9% (114/818) were polymicrobial KP-BSI. The severity of illness in polymicrobial and monomicrobial KP-BSI was similar, while the rate of resistance to carbapenems was obviously higher in polymicrobial KP-BSI (78.1% vs. 65.6%, p = 0.009 ). On multivariate analysis, hospitalization in burn ward (odds ratio (OR) 6.13, 95% confidence interval (CI) 2.00-18.76, p = 0.001 ) and intensive care unit (OR 2.39, 95% CI 1.05-5.43, p = 0.038 ) was independently associated with polymicrobial KP-BSI. Gram-negative bacteria accounted for the highest proportion (68.9%) among copathogens of polymicrobial KP-BSI, whereas gram-positive bacteria (22.9%) and Candida (8.2%) ranked the second and the third, respectively, with Acinetobacter baumannii being the most common (23.0%). Patients with polymicrobial KP-BSI had longer hospital days after BSI onset and total hospital days than patients with monomicrobial KP-BSI (median (interquartile range (IQR)), 19 (5, 39) vs. 12 (6, 25), 37 (21, 67) vs. 29 (16, 53), respectively, p < 0.05 ). The mortality did not differ between polymicrobial KP-BSI and monomicrobial KP-BSI (all p > 0.05 ). Conclusions. It was observed that polymicrobial KP-BSI accounted for a significant proportion among all KP-BSI in the current study. Hospitalization in burn ward and intensive care unit was an independent risk factor for the development of polymicrobial KP-BSI. The patients with polymicrobial KP-BSI had a higher rate of carbapenem-resistant K. pneumoniae and might have poor outcomes compared to monomicrobial KP-BSI.

We isolated 47 Acinetobacter strains carrying tet (X3) and 4 ST767 E. coli strains carrying tet (X4) from 296 rectal swab samples from dairy cows on a Chinese farm. tet (X3) was located on chromosomes or diverse plasmids, and tet (X4) was located on IncFIBκ/FIA(HI1)/X1 nontransferable plasmid. The coexistence of tet (X3) and carbapenemase genes, including bla OXA-58 and bla NDM-1 , was detected in 9 Acinetobacter spp.

Purpose The purpose of this study was to explore the clinical features, risk factors, and outcomes of mixed Candida albicans/bacterial bloodstream infections (mixed-CA/B-BSIs) compared with monomicrobial Candida albicans bloodstream infection (mono-CA-BSI) in adult patients in China. Methods All hospitalized adults with Candida albicans bloodstream infection (CA-BSI) were recruited for this retrospective observational study from January 1, 2013, to December 31, 2018. Results Of the 117 patients with CA-BSI, 24 patients (20.5%) had mixed-CA/B-BSIs. The most common copathogens were coagulase-negative Staphylococcus (CNS) (24.0%), followed by Klebsiella pneumoniae (20.0%) and Staphylococcus aureus (16.0%). In the multivariable analysis, a prior ICU stay > 2 days (adjusted odds ratio [OR], 7.445; 95% confidence interval [CI], 1.152–48.132) was an independent risk factor for mixed-CA/B-BSIs. Compared with patients with mono-CA-BSI, patients with mixed-CA/B-BSIs had a prolonged length of mechanical ventilation [17.5 (4.5, 34.8) vs. 3.0 (0.0, 24.5), p = 0.019] and prolonged length of ICU stay [22.0 (14.3, 42.2) vs. 8.0 (0.0, 31.5), p = 0.010]; however, mortality was not significantly different. Conclusions There was a high rate of mixed-CA/B-BSIs cases among CA-BSI cases, and CNS was the predominant coexisting species. A prior ICU stay > 2 days was an independent risk factor for mixed -CA/B-BSIs. Although there was no difference in mortality, the outcomes of patients with mixed -CA/B-BSIs, including prolonged length of mechanical ventilation and prolonged length of ICU stay, were worse than those with mono-CA-BSI; this deserves further attention from clinicians.

Background Although Staphylococcus aureus bloodstream infections (SA-BSI) are a common and important infection, polymicrobial SA-BSI are infrequently reported. The aim of this study was to investigate the clinical characteristics and risk factors of polymicrobial SA-BSI in comparison with monomicrobial SA-BSI. Methods A single-center retrospective observational study was performed between Jan 1, 2013, and Dec 31, 2018 at a tertiary hospital. All patients with SA-BSI were enrolled, and their clinical data were gathered by reviewing electronic medical records. Results A total of 349 patients with SA-BSI were enrolled including 54 cases (15.5%) with polymicrobial SA-BSI. In multivariable analysis, burn injury (adjusted odds ratio [OR], 7.04; 95% confidence interval [CI], 1.71–28.94), need of blood transfusion (aOR, 2.72; 95% CI, 1.14–6.50), use of mechanical ventilation (aOR, 3.11; 95% CI, 1.16–8.30), the length of prior hospital stay (aOR, 1.02; 95% CI, 1.00–1.03), and pneumonia as primary site of infection (aOR, 4.22; 95% CI, 1.69–10.51) were independent factors of polymicrobial SA-BSI. In comparison with monomicrobial SA-BSI, patients with polymicrobial SA-BSI had longer length of ICU stay [median days, 23(6.25,49.25) vs. 0(0,12), p p p = 0.01). Conclusions Burn injury, blood transfusion, mechanical ventilation, the length of prior hospital stay, and pneumonia as a primary site of infection are independent risk factors for polymicrobial SA-BSI. In addition, patients with polymicrobial SA-BSI might have worse outcomes compared with monomicrobial SA-BSI.

Whether autophagy affects methicillin-resistant Staphylococcus aureus (MRSA)-induced sepsis and the associated mechanisms are largely unknown. This study investigated the role of autophagy in MRSA-induced sepsis. The levels of microtubule-associated protein light chain 3 (LC3)-II/I, Beclin-1 and p62 after USA300 infection were examined by Western blotting and immunohistochemical staining. Bacterial burden analysis, hematoxylin-eosin staining, and Kaplan-Meier analysis were performed to evaluate the effect of autophagy on MRSA-induced sepsis. IFN-γ and IL-17 were analyzed by ELISA, and CD4+ T cell differentiation was assessed by flow cytometry. Our results showed that LC3-II/I and Beclin-1 were increased, while p62 was decreased after infection. Survival rates were decreased in the LC3B-/- and Beclin-1+/- groups, accompanied by worsened organ injuries and increased IFN-γ and IL-17 levels, whereas rapamycin alleviated organ damage, decreased IFN-γ and IL-17 levels, and improved the survival rate. However, there was no significant difference in bacterial burden. Flow cytometric analysis showed that rapamycin treatment decreased the frequencies of Th1 and Th17 cells, whereas these cells were upregulated in the LC3B-/- and Beclin-1+/- groups. Therefore, autophagy plays a protective role in MRSA-induced sepsis, which may be partly associated with the alleviation of organ injuries via the downregulation of Th1 and Th17 responses. These results provide a nonantibiotic treatment strategy for sepsis.

vanM, an uncommon glycopeptide resistance gene, was first identified in an Enterococcus faecium isolate (Efm-HS0661) from Shanghai, China, in 2006 and has been predominant in this city since 2011. A vanM-carrying E. faecium was isolated from the bloodstream of a patient in an intensive care unit (ICU) in Hangzhou, China, in 2014. Further surveillance screening of a rectal swab and environmental surfaces of the patient yielded a large number of vanM-positive E. faecium. These isolates (including 1 from the bloodstream, 1 from the rectal swab and 43 representative isolates from environmental samples) were classified into four pulsed-field gel electrophoresis (PFGE) patterns and two sequence types (ST78 and ST564). PCR amplification and sequence analysis indicated that the genetic structure surrounding the vanM gene of these isolates was similar to that of the original vanM-carrying isolate Efm-HS0661. This study highlights the emergence of infections and environmental contamination caused by vanM-carrying E. faecium in an ICU of another Chinese city outside of Shanghai.

Purpose Although the enterococcal bloodstream infections (EBSI) are often observed in clinic, the mixed-EBSI are few reported. The aim of this study was to investigate the clinical characteristics and risk factors of mixed-EBSI in comparison with monomicrobial EBSI (mono-EBSI). Methods A single-center retrospective observational study was performed between Jan 1, 2013 and Dec 31, 2018 in a tertiary hospital. All patients with EBSI were enrolled, and their data were collected by reviewing electronic medical records. Results A total of 451 patients with EBSI were enrolled including 157 cases (34.8%) with mixed-EBSI. The most common co-pathogens were Coagulase-negative Staphylococcus (26.86%), followed by Acinetobacter baumannii (23.43%) and Klebsiella pneumoniae (8.57%). In multivariable analysis, burn injury (adjusted odds ratio [aOR], 7.39; 95% confidence interval [CI], 2.69–20.28), and length of prior hospital stay (aOR, 1.01; 95% CI, 1.00–1.02) were associated with mixed-EBSI. Patients with mixed-EBSI developed with more proportion of septic shock (19% vs. 31.8%, p=0.002), prolonged length of intensive care unit (ICU) stay [9(0,25) vs. 15(2.5,36), p

The recent emergence of a transferable colistin resistance mechanism, MCR-1, has gained global attention because of its threat to clinical treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, the possible transmission route of mcr-1 among Enterobacteriaceae species in clinical settings is largely unknown. Here, we present a comprehensive genomic analysis of Escherichia coli isolates collected in a hospital in Hangzhou, China. We found that mcr-1-carrying isolates from clinical infections and feces of inpatients and healthy volunteers were genetically diverse and were not closely related phylogenetically, suggesting that clonal expansion is not involved in the spread of mcr-1. The mcr-1 gene was found on either chromosomes or plasmids, but in most of the E. coli isolates, mcr-1 was carried on plasmids. The genetic context of the plasmids showed considerable diversity as evidenced by the different functional insertion sequence (IS) elements, toxin-antitoxin (TA) systems, heavy metal resistance determinants, and Rep proteins of broad-host-range plasmids. Additionally, the genomic analysis revealed nosocomial transmission of mcr-1 and the coexistence of mcr-1 with other genes encoding β-lactamases and fluoroquinolone resistance in the E. coli isolates. These findings indicate that mcr-1 is heterogeneously disseminated in both commensal and pathogenic strains of E. coli, suggest the high flexibility of this gene in its association with diverse genetic backgrounds of the hosts, and provide new insights into the genome epidemiology of mcr-1 among hospital-associated E. coli strains., IMPORTANCE Colistin represents one of the very few available drugs for treating infections caused by extensively multidrug-resistant Gram-negative bacteria. The recently emergent mcr-1 colistin resistance gene threatens the clinical utility of colistin and has gained global attention. How mcr-1 spreads in hospital settings remains unknown and was investigated by whole-genome sequencing of mcr-1-carrying Escherichia coli in this study. The findings revealed extraordinary flexibility of mcr-1 in its spread among genetically diverse E. coli hosts and plasmids, nosocomial transmission of mcr-1-carrying E. coli, and the continuous emergence of novel Inc types of plasmids carrying mcr-1 and new mcr-1 variants. Additionally, mcr-1 was found to be frequently associated with other genes encoding β-lactams and fluoroquinolone resistance. These findings provide important information on the transmission and epidemiology of mcr-1 and are of significant public health importance as the information is expected to facilitate the control of this significant antibiotic resistance threat.

Emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that also exhibit resistance to tigecycline and colistin have become a major clinical concern, as these two agents are the last-resort antibiotics used for treatment of CRKP infections. A leukemia patient infected with CRKP was subjected to follow-up analysis of variation in phenotypic and genotypic characteristics of CRKP strains isolated from various specimens at different stages of treatment over a period of 3 years. Our data showed that (1) carbapenem treatment led to the emergence of CRKP in the gastrointestinal (GI) tract of the patient, which subsequently caused infections at other body sites as well as septicemia; (2) treatment with tigecycline led to the emergence of tigecycline-resistant CRKP, possibly through induction of the expression of a variant tet(A) gene located in a conjugative plasmid; (3) colistin treatment was effective in clearing CRKP from the bloodstream but led to the emergence of mcr-1-positive Enterobacteriaceae strains as well as colistin-resistant CRKP in the GI tract due to inactivation of the mgrB gene; and (4) tigecycline- and colistin-resistant CRKP could persist in the human GI tract for a prolonged period even without antibiotic selection pressure. In conclusion, clinical CRKP strains carrying a conjugative plasmid that harbors the blaKPC-2 and tet(A) variant genes readily evolve into tigecycline- and colistin-resistant CRKP upon treatment with these two antibiotics and persist in the human GI tract.

Combined treatment with caspofungin and trimethoprim/sulfamethoxazole (TMP/SMZ) as salvage therapy in non-HIV positive patients with severe pneumocystis pneumonia (PCP) yields poor outcomes. It remains unknown whether the use of this combination strategy as a first-line therapy would improve patient outcomes. The present study aimed to assess the efficacy of caspofungin combined with TMP/SMZ as a first-line therapy in non-HIV positive patients with severe PCP. A retrospective cohort study was conducted between March 2016 and February 2017. Patient clinical characteristics and outcomes were compared between two groups receiving first-line and second-line therapy respectively. In addition, similar cases from previous studies were assessed. A total of 14 patients were included in the present study (mean age, 58.79±14.41 years); including 9 patients receiving caspofungin and TMP/SMZ as a first-line therapy and 5 that received it as a second-line therapy. The overall positive response rate was 71.43% (10/14), with 88.89 (8/9) and 40.00% (2/5) in the first-line and second-line therapy groups, respectively (P=0.095). The positive response rates of patients requiring invasive mechanical ventilation differed significantly between the first-line (5/6, 83.33%) and the second-line (0/3, 0%) therapy groups (P=0.048). All-cause hospital mortality was 42.86% (6/14), with mortality rates of 33.33 (3/9) and 60.00% (3/5) in the first-line and second-line therapy groups, respectively (P=0.580). Combined with previously reported cases (n=27), the positive response rate was significantly greater in the first-line therapy group (11/12, 91.67%) than in the second-line therapy group (8/15, 53.33%, P=0.043). No significant differences were in all-cause mortality rates between the two groups (25.00 vs. 46.67%, P=0.424) were identified, despite the fact that all-course mortality in the first-line therapy group was ~50% that of the second-line therapy group. Therefore, the results of the present study indicate that combined caspofungin and TMP/SMZ as first-line therapy may be a promising and effective strategy to treat non-HIV positive patients with severe PCP, particularly for those requiring invasive mechanical ventilation.

Objectives The oxazolidinone-resistant Enterococcus faecalis E349 from a human patient tested negative for the cfr gene and 23S rRNA mutations. Here we report the identification of a novel oxazolidinone resistance gene, optrA, and a first investigation of the extent to which this gene was present in E. faecalis and Enterococcus faecium from humans and food-producing animals. Methods The resistance gene optrA was identified by whole-plasmid sequencing and subsequent cloning and expression in a susceptible Enterococcus host. Transformation and conjugation assays served to investigate the transferability of optrA. All optrA-positive E. faecalis and E. faecium isolates of human and animal origin were analysed for their MICs and their genotype, as well as the location of optrA. Results The novel plasmid-borne ABC transporter gene optrA from E. faecalis E349 conferred combined resistance or elevated MICs (when no clinical breakpoints were available) to oxazolidinones (linezolid and tedizolid) and phenicols (chloramphenicol and florfenicol). The corresponding conjugative plasmid pE349, on which optrA was located, had a size of 36 331 bp and also carried the phenicol exporter gene fexA. The optrA gene was functionally expressed in E. faecalis, E. faecium and Staphylococcus aureus. It was detected more frequently in E. faecalis and E. faecium from food-producing animals (20.3% and 5.7%, respectively) than from humans (4.2% and 0.6%, respectively). Conclusions Enterococci with elevated MICs of linezolid and tedizolid should be tested not only for 23S rRNA mutations and the gene cfr, but also for the novel resistance gene optrA.