Immune-stealth VP28-conjugated heparin nanoparticles for enhanced and reversible anticoagulation.

Heparins are a family of sulfated linear negatively charged polysaccharides that have been widely used for their anticoagulant, antithrombotic, antitumor, anti-inflammatory, and antiviral properties. Additionally, it has been used for acute cerebral infarction relief as well as other pharmacological actions. However, heparin's self-aggregated macrocomplex may reduce blood circulation time and induce life-threatening thrombocytopenia (HIT) complicating the use of heparins. Nonetheless, the conjugation of heparin to immuno-stealth biomolecules may overcome these obstacles. An immunostealth recombinant viral capsid protein (VP28) was expressed and conjugated with heparin to form a novel nanoparticle (VP28-heparin). VP28-heparin was characterized and tested to determine its immunogenicity, anticoagulation properties, effects on total platelet count, and risk of inducing HIT in animal models. The synthesized VP28-heparin trimeric nanoparticle was non-immunogenic, possessed an average hydrodynamic size (8.81 ± 0.58 nm) optimal for the evasion renal filtration and reticuloendothelial system uptake (hence prolonging circulating half-life). Additionally, VP28-heparin did not induce mouse death or reduce blood platelet count when administered at a high dosein vivo(hence reducing HIT risks). The VP28-heparin nanoparticle also exhibited superior anticoagulation properties (2.2× higher prothrombin time) and comparable activated partial thromboplastin time, but longer anticoagulation period when compared to unfractionated heparin. The anticoagulative effects of the VP28-heparin can also be reversed using protamine sulfate. Thus, VP28-heparin may be an effective and safe heparin derivative for therapeutic use.

Whole-genome-sequence-based characterization of an NDM-5-producing uropathogenic Escherichia coli EC1390.

BACKGROUND: Urinary tract infection (UTI) is one of the most common outpatient bacterial infections. In this study, we isolated and characterized an extensively-drug resistant (XDR) NDM-5-producing Escherichia coli EC1390 from a UTI patient by using whole-genome sequencing (WGS) in combination with phenotypic assays. METHODS: Antimicrobial susceptibility to 23 drugs was determined by disk diffusion method. The genome sequence of EC1390 was determined by Nanopore MinION MK1C platform. Conjugation assays were performed to test the transferability of EC1390 plasmids to E. coli recipient C600. Phenotypic assays, including growth curve, biofilm formation, iron acquisition ability, and cell adhesion, were performed to characterize the function of EC1390 plasmids. RESULTS: Our results showed that EC1390 was only susceptible to tigecycline and colistin, and thus was classified as XDR E. coli. A de novo genome assembly was generated using Nanopore 73,050 reads with an N50 value of 20,936 bp and an N90 value of 7,624 bp. WGS analysis showed that EC1390 belonged to the O101-H10 serotype and phylogenetic group A E. coli. Moreover, EC1390 contained 2 conjugative plasmids with a replicon IncFIA (pEC1390-1 with 156,286 bp) and IncFII (pEC1390-2 with 71,840 bp), respectively. No significant difference was observed in the bacterial growth rate in LB broth and iron acquisition ability between C600, C600 containing pEC1390-1, C600 containing pEC1390-2, and C600 containing pEC1390-1 and pEC1390-2. However, the bacterial growth rate in nutrition-limited M9 broth was increased in C600 containing pEC1390-2, and the cell adhesion ability was increased in C600 containing both pEC1390-1 and pEC1390-2. Moreover, these plasmids modulated the biofilm formation under different conditions. CONCLUSIONS: In summary, we characterized the genome of XDR-E. coli EC1390 and identified two plasmids contributing to the antimicrobial resistance, growth of bacteria in a nutrition-limited medium, biofilm formation, and cell adhesion.

Development of Bactericidal Peptides against Multidrug-Resistant Acinetobacter baumannii with Enhanced Stability and Low Toxicity.

Pathogenic superbugs are the root cause of untreatable complex infections with limited or no treatment options. These infections are becoming more common as clinical antibiotics have lost their effectiveness over time. Therefore, the development of novel antibacterial agents is urgently needed to counter these microbes. Antimicrobial peptides (AMPs) are a viable treatment option due to their bactericidal potency against multiple microbial classes. AMPs are naturally selected physiological microbicidal agents that are found in all forms of organisms. In the present study, we developed two tilapia piscidin 2 (TP2)-based AMPs for antimicrobial application. Unlike the parent peptide, the redesigned peptides showed significant antimicrobial activity against multidrug-resistant bacterial species. These peptides also showed minimal cytotoxicity. In addition, they were significantly active in the presence of physiological salts, 50% human serum and elevated temperature. The designed peptides also showed synergistic activity when combined with clinical antibiotics. The current approach demonstrates a fruitful strategy for developing potential AMPs for antimicrobial application. Such AMPs have potential for progression to further trials and drug development investigations.

In vitro and in vivo activities of imipenem combined with BLI-489 against class D ß-lactamase-producing Acinetobacter baumannii.

BACKGROUND: According to our preliminary study, BLI-489 has the potential to inhibit the hydrolysing activity of OXA-51-like ß-lactamase produced by carbapenem-resistant Acinetobacter baumannii (CRAb). OBJECTIVES: In the present study, the in vitro and in vivo activities of imipenem combined with BLI-489 against CRAb producing carbapenem-hydrolysing class D ß-lactamases (CHDLs), namely OXA-23, OXA-24, OXA-51 and OXA-58, were determined. METHODS: A chequerboard analysis of imipenem and BLI-489 was performed using 57 and 7 clinical CRAb isolates producing different CHDLs and MBLs, respectively. Four representative strains harbouring different CHDL genes were subjected to a time-kill assay to evaluate the synergistic effects. An in silico docking analysis was conducted to simulate the interactions between BLI-489 and the different families of CHDLs. The in vivo activities of this combination were assessed using a Caenorhabditis elegans survival assay and a mouse pneumonia model. RESULTS: Chequerboard analysis showed that imipenem and BLI-489 had a synergistic effect on 14.3, 92.9, 100, 16.7 and 100% of MBL-, OXA-23-, OXA-24-like-, OXA-51-like- and OXA-58-producing CRAb isolates, respectively. In the time-kill assay, imipenem and BLI-489 showed synergy against OXA-24-like-, OXA-51-like- and OXA-58-, but not OXA-23-producing CRAb isolates after 24 h. The in silico docking analysis showed that BLI-489 could bind to the active sites of OXA-24 and OXA-58 to confer strong inhibition activity. The combination of imipenem and BLI-489 exhibited synergistic effects for the rescue of CRAb-infected C. elegans and mice. CONCLUSIONS: Imipenem combined with BLI-489 has synergistic effects against CHDL-producing CRAb isolates.

Clinical and molecular characterization of Acinetobacter seifertii in Taiwan.

OBJECTIVES: Acinetobacter seifertii, a new member of the Acinetobacter baumannii group, has emerged as a cause of severe infections in humans. We investigated the clinical and molecular characteristics of A. seifertii. PATIENTS AND METHODS: This retrospective study enrolled 80 adults with A. seifertii bloodstream infection (BSI) at four medical centres over an 8 year period. Species identification was confirmed by MALDI-TOF MS, rpoB sequencing and WGS. Molecular typing was performed by MLST. Clinical information, antimicrobial susceptibility and the mechanisms of carbapenem and colistin resistance were analysed. Transmissibility of the carbapenem-resistance determinants was examined by conjugation experiments. RESULTS: The main source of A. seifertii BSI was the respiratory tract (46.3%). The 28 day and in-hospital mortality rates of A. seifertii BSI were 18.8% and 30.0%, respectively. High APACHE II scores and immunosuppressant therapy were independent risk factors for 28 day mortality. The most common MLST type was ST553 (58.8%). Most A. seifertii isolates were susceptible to levofloxacin (86.2%), and only 37.5% were susceptible to colistin. Carbapenem resistance was observed in 16.3% of isolates, mostly caused by the plasmid-borne ISAba1-blaOXA-51-like genetic structure. A. seifertii could transfer various carbapenem-resistance determinants to A. baumannii, Acinetobacter nosocomialis and other A. seifertii isolates. Variations of pmrCAB and lpxCAD genes were not associated with colistin resistance of A. seifertii. CONCLUSIONS: Levofloxacin and carbapenems, but not colistin, have the potential to be the drug of choice for A. seifertii infections. A. seifertii can transfer carbapenem-resistance determinants to other species of the A. baumannii group and warrants close monitoring.

Initial white blood cell count and revised Baux score predict subsequent bloodstream infection in burn patients: A retrospective analysis of severe burn patients from the Formosa color dust explosion of 2015.

BACKGROUND: Infections are the most common complications among hospitalized severe burn patients. However, limited literature reports early effective predictors of bloodstream infections (BSI) among burn patients. This study aimed to identify cost-effective biomarkers and valuable clinical scoring systems in the emergency department (ED) for the prediction of subsequent BSI in mass burn casualties. METHODS: In 2015, a flammable cornstarch-based powder explosion resulted in 499 burn casualties in Taiwan. A total of 35 patients were admitted at Taipei Veterans General Hospital. These severe burn patients (median total body surface area [TBSA] 54%) were young and previously healthy. We assessed the potential of various parameters to predict subsequent BSI, including initial laboratory tests performed at the ED, TBSA, and multiple scoring systems. RESULTS: Fourteen patients (40.0%) had subsequent BSI. The most common causative pathogen was the Acinetobacter baumannii (Ab) group, mostly carbapenem resistant and associated with a poor outcome. The area under the receiver operating characteristic curve revealed that the revised Baux score, TBSA, and initial white blood cell count had excellent discrimination ability in predicting subsequent BSI (0.898, 0.889, and 0.821, respectively). The rate of subsequent BSI differed significantly at the cut-off points of revised Baux score >76, TBSA >55%, and WBC count >16,200/mm3. CONCLUSION: The initial WBC count at the ED, TBSA, and revised Baux score were good and cost-effective biomarkers for predicting subsequent BSI after burn injuries.

Comparison of Cefepime-Cefpirome and Carbapenem Therapy for Acinetobacter Bloodstream Infection in a Multicenter Study.

Carbapenems are currently the preferred agents for the treatment of serious Acinetobacter infections. However, whether cefepime-cefpirome can be used to treat an Acinetobacter bloodstream infection (BSI) if it is active against the causative pathogen(s) is not clear. This study aimed to compare the efficacy of cefepime-cefpirome and carbapenem monotherapy in patients with Acinetobacter BSI. The population included 360 patients with monomicrobial Acinetobacter BSI receiving appropriate antimicrobial therapy admitted to four medical centers in Taiwan in 2012 to 2017. The predictors of 30-day mortality were determined by Cox regression analysis. The overall 30-day mortality rate in the appropriate antibiotic treatment group was 25.0% (90/360 patients). The crude 30-day mortality rates for cefepime-cefpirome and carbapenem therapy were 11.5% (7/61 patients) and 26.3% (21/80 patients), respectively. The patients receiving cefepime-cefpirome or carbapenem therapy were infected by Acinetobacter nosocomialis (51.8%), Acinetobacter baumannii (18.4%), and Acinetobacter pittii (12.1%). After adjusting for age, Sequential Organ Failure Assessment (SOFA) score, invasive procedures, and underlying diseases, cefepime-cefpirome therapy was not independently associated with a higher or lower 30-day mortality rate compared to that with the carbapenem therapy. SOFA score (hazard ratio [HR], 1.324; 95% confidence interval [CI], 1.137 to 1.543; P < 0.001) and neutropenia (HR, 7.060; 95% CI, 1.607 to 31.019; P = 0.010) were independent risk factors for 30-day mortality of patients receiving cefepime-cefpirome or carbapenem monotherapy. The incidence densities of 30-day mortality for cefepime-cefpirome versus carbapenem therapy were 0.40% versus 1.04%, respectively. The therapeutic response of cefepime-cefpirome therapy was comparable to that with carbapenems among patients with Acinetobacter BSI receiving appropriate antimicrobial therapy.

Hiccups as the only symptom of acute myocardial infarction.

Hiccups are usually benign, while myocardial infarction (MI) has the potential for morbidity and mortality. Here, we report 3 cases of MI, with hiccups being the only symptom on presentation to the emergency department. Attention should be given to patients who present with hiccups and multiple risk factors for acute coronary syndrome, especially those with factors predisposing them to atypical presentations, such as diabetes mellitus, and old age.

Risk of Mortality of Catheter-Related Bloodstream Infections Caused by Acinetobacter Species: Is Early Removal of the Catheters Associated With a Better Survival Outcome?

PURPOSE: Bloodstream infections (BSIs) caused by Acinetobacter species have been extensively reported, however, which majorly focused on respiratory tract infections. The risk of mortality and the effect of early catheter removal on survival in catheter-related BSIs (CRBSIs) caused by Acinetobacter spp. remain unclear. This study aims to investigate that. METHODS: This is a retrospective multicentric study conducted in Taiwan from 2012 to 2014. Patients with at least 1 positive blood culture and catheter culture for the same Acinetobacter spp., showing symptoms and signs of CRBSIs, were included (n = 119). Risk factors for 30-day mortality were analyzed using a logistic regression model. The characteristics of patients with early catheter removal (within 48 hours after CRBSIs) were compared to those without removal matching for age, sex, and disease severity. RESULTS: There were no differences in 30-day mortality with regard to causative Acinetobacter spp., catheter type, site, and appropriateness of antimicrobial therapy. Patients with higher Acute Physiologic and Chronic Health Evaluation (APACHE) II scores (odds ratio [OR]: 1.12; 95% confidence interval [CI]: 1.02-1.23; P = .014), shock (OR: 6.43; 95% CI: 1.28-32.33; P = .024), and longer hospitalization before CRBSIs (OR: 1.04; 95% CI: 1.00-1.08; P = .027) had a significantly higher 30-day mortality rate. Early removal of catheters after CRBSIs was not associated with better survival benefits. CONCLUSION: Higher disease severity (APACHE II score), shock, and longer hospitalization before bacteremia were independently associated with a higher 30-day mortality in CRBSIs caused by Acinetobacter spp. In previous published guidelines, infected catheters were suggested to be removed in CRBSIs caused by gram-negative bacilli. Even though early removal of catheters did not associate with a better survival outcome in current results, it should be judiciously evaluated according to the clinical conditions and risks individually. For better elucidation of these issues, further well-controlled prospective study may be warranted.

Multicenter Study of Clinical Features of Breakthrough Acinetobacter Bacteremia during Carbapenem Therapy.

Breakthrough Acinetobacter bacteremia during carbapenem therapy is not uncommon, and it creates therapeutic dilemmas for clinicians. This study was conducted to evaluate the clinical and microbiological characteristics of breakthrough Acinetobacter bacteremia during carbapenem therapy and to assess the efficacy of various antimicrobial therapies. We analyzed 100 adults who developed breakthrough Acinetobacter bacteremia during carbapenem therapy at 4 medical centers over a 6-year period. Their 30-day mortality rate was 57.0%, and the carbapenem resistance rate of their isolates was 87.0%. Among patients with carbapenem-resistant Acinetobacter bacteremia, breakthrough bacteremia during carbapenem therapy was associated with a significantly higher 14-day mortality (51.7% versus 37.4%, respectively; P = 0.025 by bivariate analysis) and a higher 30-day mortality (P = 0.037 by log rank test of survival analysis) than in the nonbreakthrough group. For the treatment of breakthrough Acinetobacter bacteremia during carbapenem therapy, tigecycline-based therapy was associated with a significantly higher 30-day mortality (80.0%) than those with continued carbapenem therapy (52.5%) and colistin-based therapy (57.9%) by survival analysis (P = 0.047 and 0.045 by log rank test, respectively). Cox regression controlling for confounders, including severity of illness indices, demonstrated that treatment with tigecycline-based therapy for breakthrough Acinetobacter bacteremia was an independent predictor of 30-day mortality (hazard ratio, 3.659; 95% confidence interval, 1.794 to 7.465; P < 0.001). Patients with breakthrough Acinetobacter bacteremia during carbapenem therapy posed a high mortality rate. Tigecycline should be used cautiously for the treatment of breakthrough Acinetobacter bacteremia that develops during carbapenem therapy.

Multicenter Study of the Relationship between Carbapenem MIC Values and Clinical Outcome of Patients with Acinetobacter Bacteremia.

The Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) offer different recommendations for carbapenem MIC susceptibility breakpoints for Acinetobacter species. In addition, the clinical efficacy of the intermediate category remains uncertain. This study was designed to determine the optimal predictive breakpoints based on the survival of patients with Acinetobacter bacteremia treated with a carbapenem. We analyzed the 30-day mortality rates of 224 adults who received initial carbapenem monotherapy for the treatment of Acinetobacter bacteremia at 4 medical centers over a 5-year period, according to the carbapenem MICs of the initial isolates. The 30-day mortality was about 2-fold greater in patients whose isolates had carbapenem MICs of ≥8 mg/liter than in those with isolates with MICs of ≤4 mg/liter. The differences were significant by bivariate analysis (53.1% [60/113] versus 25.2% [28/111], respectively; P < 0.001) and on survival analysis by the log rank test (P < 0.001). Classification and regression tree analysis revealed a split between MICs of 4 and 8 mg/liter and predicted the same difference in mortality, with a P value of <0.001. Carbapenem treatment for Acinetobacter bacteremia caused by isolates with carbapenem MICs of ≥8 mg/liter was an independent predictor of 30-day mortality (odds ratio, 4.218; 95% confidence interval, 2.213 to 8.039; P < 0.001). This study revealed that patients with Acinetobacter bacteremia treated with a carbapenem had a more favorable outcome when the carbapenem MICs of their isolates were ≤4 mg/liter than those with MICs of ≥8 mg/liter.

Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture.

Acinetobacter baumannii biofilms are difficult to eradicate. We investigated the effects of meropenem (2 mg/liter), imipenem (2 mg/liter), sulbactam (4 mg/liter), colistin (2 mg/liter), and tigecycline (2 mg/liter), alone or in combination, on biofilm-embedded carbapenem-resistant and carbapenem-susceptible A. baumannii (CRAb and CSAb, respectively) cells, as well as on the architecture of the biofilms. A. baumannii ATCC 15151 (Ab15151) and its OXA-82-overproducing transformant, along with two clinical CSAb and two clinical CRAb isolates of differing clonalities, were used. The minimal bactericidal concentrations for biofilm-embedded cells of the six tested isolates were >50-fold those of their planktonic cells. When used individually, meropenem exhibited a higher killing effect than the other four antimicrobials on biofilm-embedded CSAb cells in the colony biofilm assay. For two clinical CRAb isolates, meropenem plus sulbactam or sulbactam plus tigecycline showed >100-fold the bactericidal effect exhibited by these agents used alone after 48 h of treatment. The effect of antimicrobials on the architecture of Ab15151 biofilm emitting green fluorescence was determined by confocal laser scanning microscopy using COMSTAT software. Significant decreases in the maximum biofilm thickness were observed after exposure to meropenem and imipenem. Meropenem plus sulbactam significantly decreased the biomass and mean thickness and increased the roughness coefficient of biofilms, but sulbactam plus tigecycline only decreased the maximum and mean biofilm thickness compared to any of these agents used alone. Meropenem was active against biofilm-embedded CSAb, whereas meropenem plus sulbactam exhibited synergism against biofilm-embedded CRAb and caused significantly more damage to the biofilm architecture than did any of the agents used alone.

In vitro activity of SecA inhibitors in combination with carbapenems against carbapenem-hydrolysing class D ß-lactamase-producing Acinetobacter baumannii.

OBJECTIVES: According to our previous study, OXA-58 translocates to the periplasm via the Sec pathway in carbapenem-resistant Acinetobacter baumannii (CRAb). In the present study, carbapenem-hydrolysing class D ß-lactamases (CHDLs) belonging to the OXA-23, OXA-40 and OXA-51 families were examined to determine whether they are also Sec-dependent. Additionally, the effects of SecA inhibitors combined with carbapenems against CHDL-producing CRAb were examined. METHODS: Cell fractionation and western blot analyses were performed to detect periplasmic His-tagged CHDLs. A chequerboard analysis with pairwise combinations of carbapenems (imipenem or meropenem) and SecA inhibitors (rose bengal, sodium azide or erythrosin B) was performed using six clinical CRAb isolates harbouring different CHDL genes. The fractional inhibitory concentration (FIC) index was determined. The combination with the lowest FIC index was subjected to a time-kill analysis to examine synergistic effects. RESULTS: In an in silico analysis, the CHDLs OXA-23, OXA-40 and OXA-51 were preferentially translocated via the Sec system. The SecA inhibitor rose bengal decreased periplasmic translocation of His-tagged OXA-23 and OXA-83 (belonging to the OXA-51 family), but not OXA-72 (belonging to the OXA-40 family) from ATCC 15151 transformants. Imipenem or meropenem with rose bengal showed synergistic effects (FIC index, ≤0.5) for six and four clinical isolates, respectively. Imipenem or meropenem with sodium azide showed no interactions (FIC index, 0.5-4) against all clinical isolates. Imipenem and rose bengal had the lowest FIC index and showed synergy at 24 h in the time-kill assay. CONCLUSIONS: Combinations of SecA inhibitors and carbapenems have synergistic effects against CHDL-producing CRAb.

Efficacy of tigecycline for secondary Acinetobacter bacteremia and factors associated with treatment failure.

We describe the clinical outcome of 17 patients with secondary Acinetobacter bacteremia whose isolates had a tigecycline MIC of ≤2 mg/liter and who received tigecycline within 2 days of bacteremia onset. The 14-day mortality rate of the tigecycline cohort was 41.2% (7/17), which was significantly higher than that of those receiving other appropriate antimicrobial agents (13.8%, 9/65; P = 0.018). However, the percentages of end-stage renal disease and congestive heart failure were higher in the tigecycline cohort. The efficacy of tigecycline was contingent upon the illness severity and bacterial species. Tigecycline should be applied cautiously for treatment of Acinetobacter bacteremia.

Acinetobacter baumannii Extracellular OXA-58 Is Primarily and Selectively Released via Outer Membrane Vesicles after Sec-Dependent Periplasmic Translocation.

Carbapenem-resistant Acinetobacter baumannii (CRAb) shelter cohabiting carbapenem-susceptible bacteria from carbapenem killing via extracellular release of carbapenem-hydrolyzing class D ß-lactamases, including OXA-58. However, the mechanism of the extracellular release of OXA-58 has not been elucidated. In silico analysis predicted OXA-58 to be translocated to the periplasm via the Sec system. Using cell fractionation and Western blotting, OXA-58 with the signal peptide and C terminus deleted was not detected in the periplasmic and extracellular fractions. Overexpression of enhanced green fluorescent protein fused to the OXA-58 signal peptide led to its periplasmic translocation but not extracellular release, suggesting that OXA-58 is selectively released. The majority of the extracellular OXA-58 was associated with outer membrane vesicles (OMVs). The OMV-associated OXA-58 was detected only in a strain overexpressing OXA-58. The presence of OXA-58 in OMVs was confirmed by a carbapenem inactivation bioassay, proteomic analysis, and transmission electron microscopy. Imipenem treatment increased OMV formation and caused cell lysis, resulting in an increase in the OMV-associated and OMV-independent release of extracellular OXA-58. OMV-independent OXA-58 hydrolyzed nitrocefin more rapidly than OMV-associated OXA-58 but was more susceptible to proteinase K degradation. Rose bengal, an SecA inhibitor, inhibited the periplasmic translocation and OMV-associated release of OXA-58 and abolished the sheltering effect of CRAb. This study demonstrated that the majority of the extracellular OXA-58 is selectively released via OMVs after Sec-dependent periplasmic translocation. Addition of imipenem increased both OMV-associated and OMV-independent OXA-58, which may have different biological roles. SecA inhibitor could abolish the carbapenem-sheltering effect of CRAb.

A retrospective study of the incidence, clinical characteristics, identification, and antimicrobial susceptibility of bacteremic isolates of Acinetobacter ursingii.

BACKGROUND: Acinetobacter ursingii bacteremia is rarely reported. We investigated the incidence and clinical features of A. ursingii bacteremia, performance of the identification system, and antimicrobial susceptibility of the isolates. Acinetobacter ursingii bacteremia patients were compared with A. baumannii bacteremia patients. METHODS: In this 9-year retrospective study, A. ursingii was identified using 16S rRNA and 16S-23S rRNA internal transcribed spacer sequence analysis. The performances of the Vitek 2, Phoenix, and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometer systems for identifying isolates were tested. Pulsed-field gel electrophoresis (PFGE) was used to determine the clonality of the isolates. The minimal inhibitory concentrations of the antimicrobials were determined using the Vitek 2 system. RESULTS: Nineteen patients were identified. Acinetobacter ursingii was noted in 1.5-5.2 % of all Acinetobacter bacteremia cases. For the PFGE analysis, two isolates had smeared DNA, two had 93 % similarity, and 15 had similarity <80 %. Among 16 patients with complete medical records, 10 (62.5 %) had no identifiable source of A. ursingii bacteremia. Most patients (n = 12) had underlying malignant disease. Patients with A. ursingii bacteremia had lower Acute Physiology and Chronic Health Evaluation II scores than those with A. baumannii bacteremia (median [interquartile range], 17.1 [10.0-24.7] vs. 24.9 [14.6-35.1]). Patients with A. ursingii bacteremia were also less likely admitted to the intensive care unit than patients with A. baumannii bacteremia (18.8 % vs 63.5 %, p value < 0.01). About half of the patients with A. ursingii (50.8 %) and A. baumannii bacteremia (62.5 %) had received inappropriate antimicrobial therapy within 48 h after bacteremia onset. However, patients with A. ursingii bacteremia had significantly lower 14-day (6.25 % vs 29.8 %, p value = 0.04) and 28-day mortality rates (6.25 % vs 37.3 %, p value = 0.02) than patients with A. baumannii bacteremia. Nine isolates (47.4 %) were correctly identified as A. ursingii and the other 10 isolates (52.6 %) were incorrectly identified as A. lwoffii by the Vitek 2 system. The Phoenix system incorrectly identified all 19 isolates. The MALDI-TOF mass spectrometer system correctly identified all 19 isolates. All the A. ursingii isolates were resistant or showed intermediate susceptibility to ceftriaxone and ceftazidime, but were susceptible to levofloxacin and imipenem. CONCLUSIONS: Acinetobacter ursingii is a rare pathogen that mostly caused primary bacteremia in patients with malignancies. Patients with A. ursingii bacteremia had significantly lower disease severity and mortality rates than patients with A. baumannii bacteremia.

Association between recent use of proton pump inhibitors and nontyphoid salmonellosis: a nested case-control study.

BACKGROUND: The association between proton pump inhibitors (PPIs) and nontyphoid salmonellosis (NTS) continues to be debated. The current study was designed to determine the association between use of oral PPIs and the diagnosis of NTS. METHODS: The Taiwan National Health Insurance Research Database from 2000 to 2010 was searched for cases of NTS, defined by the International Classification of Disease, Ninth revision, Clinical Modification. A nested case-control study in hospitalized population was conducted using 4 controls for each case patient (14 736 case patients and 58 944 controls), matched for age, month and year of entry, Charlson comorbidity index score, and well-known predisposing factors for NTS, including autoimmune diseases, acquired immunodeficiency syndrome, diabetes, cirrhosis, transplantation, gastrointestinal operations or diseases, and malignancies. RESULTS: Persons with NTS had a higher rate of using oral PPIs within the prior year (adjusted odds ratio [OR], 2.09; 95% confidence interval [CI], 1.95-2.24; P < .001). The association was greatest for current PPI use (adjusted OR, 5.39; 95% CI, 4.79-6.06; P < .001). Although use of H2-receptor antagonists (adjusted OR, 1.84; 95% CI, 1.71-1.98), antibiotics (5.21; 4.81-5.64), steroids (3.18; 2.99-3.39), and nonsteroidal anti-inflammatory drugs (2.37; 2.26-2.48) within the 30 days were also associated with NTS, the linkage between PPI use and NTS remained significant in the subgroup without these medications. CONCLUSIONS: The use of oral PPIs was associated with the occurrence of NTS. The risk waned with time after discontinuation.

Association between recent use of fluoroquinolones and rhegmatogenous retinal detachment: a population-based cohort study.

BACKGROUND: An association between use of oral fluoroquinolones (FQs) and retinal detachment remains controversial. This study was to determine the association of recent use of oral FQs and rhegmatogenous retinal detachment (RRD) after adjustment for confounding factors known to be associated with RRD. METHODS: This retrospective population-based cohort study with parallel groups included adults treated with an oral FQ (FQ cohort = 178 179 prescriptions) and propensity score-matched adults treated with oral amoxicillin (amoxicillin cohort = 178 179 prescriptions). The data were extracted from the Taiwan National Health Insurance Research Database from 1998 to 2010. Interaction terms were used to identify populations at risk. RRD was defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification. RESULTS: During the 90-day follow-up period, 96 patients (0.054%) in the FQ cohort developed RRD compared to 46 (0.026%) among the matched amoxicillin cohort. The overall adjusted hazard ratio (HR) for FQ use and RRD was 2.07 (95% confidence interval [CI], 1.45-2.96). The interval between use of oral FQs and onset of RRD was 35.5 days (interquartile range, 14-57 days). Interaction terms were not significant for age, sex, diabetes, indications for antimicrobials, or underlying ophthalmic conditions. The adjusted HRs differed for specific FQs. These were 10.68 (95% CI, 3.28-34.82) for ciprofloxacin, 2.41 (95% CI, .76-7.68) for levofloxacin, 2.00 (95% CI, 1.06-3.79) for norfloxacin, and 1.17 (95% CI, .59-2.31) for ofloxacin. CONCLUSIONS: The use of oral FQs was associated with the subsequent occurrence of RRD. The FQ risk was independent of age, sex, diabetes, indications for antimicrobials, and underlying ophthalmic conditions. Certain FQs carried higher risk of RRD.

Sheltering effect and indirect pathogenesis of carbapenem-resistant Acinetobacter baumannii in polymicrobial infection.

The role of carbapenem-resistant Acinetobacter baumannii (CRAb) in polymicrobial infection remains elusive. Having observed the ability of CRAb to shelter other susceptible bacteria from carbapenem killing, we sought to determine the factors contributing to this sheltering effect by transforming different recombinant plasmids into recipient A. baumannii cells. The sheltering effects of CRAb were reproduced in recipient A. baumannii cells that highly expressed carbapenem-hydrolyzing class D ß-lactamases (CHDLs) through their associated strong promoter. With the use of Western blot analysis and a bioassay, the highly expressed CHDLs were found to be extracellularly released and led to hydrolysis of carbapenem. The level of extracellular CHDLs increased after challenge with a higher concentration of CHDL substrates, such as carbapenem and ticarcillin. This increased CHDL may, in part, be attributed to cell lysis, as indicated by the presence of extracellular gyrase. In the planktonic condition, the sheltering effect for the cocultured susceptible bacteria might represent an indirect and passive effect of the CRAb self-defense mechanism, because coculture with the susceptible pathogen did not augment the amount of the extracellular CHDLs. Polymicrobial infection caused by CRAb and a susceptible counterpart exerted higher pathogenicity than monomicrobial infection caused by either pathogen alone in mice receiving carbapenem therapy. This study demonstrated that CHDL-producing CRAb appears to provide a sheltering effect for carbapenem-susceptible pathogens via the extracellular release of CHDLs and, by this mechanism, can enhance the pathogenesis of polymicrobial infection in the presence of carbapenem therapy.

A 19-year longitudinal study to characterize carbapenem-nonsusceptible Acinetobacter isolated from patients with bloodstream infections and the contribution of conjugative plasmids to carbapenem resistance and virulence.

BACKGROUND: This study aimed to characterize carbapenem-nonsusceptible Acinetobacter (CNSA) isolated from patients with bacteremia from 1997 to 2015. METHODS: A total of 173 CNSA (12.3%) was recovered from 1403 Acinetobacter isolates. The presence of selected ß-lactamase genes in CNSA was determined by PCR amplification. The conjugation test was used to determine the transferability of metallo-ß-lactamase (MBL)-carrying plasmids. Whole genome sequencing in combination with phenotypic assays was carried out to characterize MBL-plasmids. RESULTS: In general, a trend of increasing numbers of CNSA was observed. Among the 173 CNSA, A. baumannii (54.9%) was the most common species, followed by A. nosocomialis (23.1%) and A. soli (12.1%). A total of 49 (28.3%) CNSA were extensively drug-resistant, and all were A. baumannii. The most common class D carbapenemase gene in 173 CNSA was blaOXA-24-like (32.4%), followed by ISAba1-blaOXA-51-like (20.8%), ISAba1-blaOXA-23 (20.2%), and IS1006/IS1008-blaOXA-58 (11.6%). MBL genes, blaVIM-11,blaIMP-1, and blaIMP-19 were detected in 9 (5.2%), 20 (11.6%), and 1 (0.6%) CNSA isolates, respectively. Transfer of MBL genes to AB218 and AN254 recipient cells was successful for 7 and 6 of the 30 MBL-plasmids, respectively. The seven AB218-derived transconjugants carrying MBL-plasmids produced less biofilm but showed higher virulence to larvae than recipient AB218. CONCLUSIONS: Our 19-year longitudinal study revealed a stable increase in CNSA during 2005-2015. blaOXA-24-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23 were the major determinants of Acinetobacter carbapenem resistance. MBL-carrying plasmids contribute not only to the carbapenem resistance but also to A. baumannii virulence.