In vitro activity of aminoglycosides,clofazimine, d-cycloserine and dapsone against 83 Mycobacterium avium complex clinical isolates

Background/Purpose

Treatment success rates for Mycobacterium avium complex (MAC) diseases range from 50% to 55% only. To explore effective antimicrobials against either Mycobacterium intracellulare or M. avium, we determined in vitro activities of five aminoglycosides, clofazimine, dapsone and d-cycloserine compared with primary (clarithromycin) and secondary (moxifloxacin and linezolid) antimycobacterial agents.

Characterization of an antimicrobial substance produced by Lactobacillus plantarum NTU 102

Background/PurposeLactic acid bacteria (LAB) are used in a variety of bio-industrial processes, including milk fermentation, and have been reported to have bactericidal activities. We previously isolated Lactobacillus plantarum NTU 102 from homemade Korean-style cabbage pickles. The aims of this work were to perform a screen of the antimicrobial substances produced by L. plantarum NTU 102 and to characterize it.MethodsIn this study, we investigated the bactericidal activity of this LAB strain and demonstrated that the cell-free supernatant of L. plantarum NTU 102 had antimicrobial activity.ResultsThe antibacterial activity was significantly decreased by proteolytic enzymes, including pepsin, proteinase K, and trypsin, suggesting that the antimicrobial substance had proteinaceous properties. Additionally, this activity was heat stable and not affected by alterations in the pH from 1.0 to 4.0. The antibacterial substance produced by L. plantarum NTU 102, which we named LBP102, exhibited a broad inhibitory spectrum. The active compound was identified by nuclear magnetic resonance (NMR) techniques (¹H NMR and ¹³C NMR). The IUPAC name was 2-(2-1 mino-1-hydroxyethoxy) ethyl 2-methylpropanoate. The substance showed antibacterial activity against Vibrio parahaemolyticus, and completely inhibited the growth of V. parahaemolyticus on agar plates at a concentration of 75 μg/mL.ConclusionThe proposed antimicrobial substance, LBP102 was found to be effective against V. parahaemolyticus BCRC 12864 and Cronobacter sakazakii BCRC 13988. The remarkable effects of LBP102 against this and other pathogens indicated its potential as a natural preservative/food additive.     

Methicillin-resistant Staphylococcus aureus nasal carriage in international medical conference attendees

Background

Carriage of methicillin-resistant Staphylococcus aureus (MRSA) is associated with its transmission. International travels and massive gatherings may accelerate such transmission. MRSA carriage was surveyed among the attendees of two international medical conferences held in Taipei in 2010.

Metabolic reprogramming of hydrogenosomal amino acids in Trichomonas vaginalis under glucose restriction

BackgroundGlucose is the major energy source that is converted to pyruvate for ATP generation in the trichomonad hydrogenosome. Under glucose restriction (GR), the regulation of amino acids metabolism is crucial for trichomonad growth and survival. RNA-sequencing (RNA-seq) analysis has been used to identify differentially expressed genes in Trichomonas vaginalis under GR, leading to significant advances in understanding adaptive responses of amino acid metabolism to GR. However, the levels of amino acid metabolites modulated by GR are unknown in T. vaginalis.MethodsHerein, we describe a comprehensive metabolomic analysis of amino acid metabolites in the hydrogenosome using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC-FT MS). The relative abundance of 17 hydrogenosomal amino acids was analyzed under GR and high-glucose (HG) conditions.ResultsLevels of most amino acids were higher in GR culture. Arginine was not detectable in either HG or GR cultures; however, its metabolic end-product proline was slightly increased under GR, suggesting that the arginine dihydrolase pathway was more activated by GR. Additionally, methionine catabolism was less stimulated under GR because of greater methionine accumulation. Furthermore, branched chain amino acids (BCAA), including leucine, isoleucine and valine, as well as phenylalanine and alanine, markedly accumulated under GR, indicating that glutamate-related metabolic pathways were remarkably enhanced in this setting. Our metabolomic analysis combined with previous RNA-seq data confirm the existence of several amino acid metabolic pathways in the hydrogenosome and highlight their potentially important roles in T. vaginalis under glucose deprivation.     

Early Detection of Left Ventricular Diverticulum by Transthoracic Echocardiography

Left ventricular diverticulum is a very rare entity to be found in adults. Noninvasive echocardiography can offer useful information prior to contrast-enhanced computer tomography or invasive angiography. We evaluated a patient with left ventricular apical diverticulum but complained no symptoms. Transthoracic echocardiography demonstrated a outpouching at left ventricle apex. A 640-slice computed tomography later confirmed the left ventricular diverticulum.     

C-reactive protein levels can predict positive 18F-FDG PET/CT findings that lead to management changes in patients with bacteremia

Background/purpose

Bacteremia portends high rates of morbidity and mortality. Although ¹⁸F-fluorodeoxyglucose positron emission tomography and computed tomography (¹⁸F-FDG PET/CT) imaging has clinical value in assessing fever of unknown origin, its usefulness in bacteremia has not been entirely elucidated. We therefore designed the current single-center retrospective study to investigate 1) the clinical value of ¹⁸F-FDG PET/CT imaging in assessing bacteremia and 2) the association between laboratory data and imaging findings.

Propensity-matched analysis of the impact of extended-spectrum β-lactamase production on adults with community-onset Escherichia coli,Klebsiella species,and Proteus mirabilis bacteremia

Background

The presence of extended-spectrum β-lactamase (ESBL) in Escherichia coli, Klebsiella species, and Proteus mirabilis (EKP) is of great microbiological and clinical importance. The study dealing with the direct impact of ESBL producers on the outcome of patients with community-onset bacteremia is lacking.

Clinical significance of human cytomegalovirus viruria and the effect of antiviral therapy in hematopoietic stem cell transplant recipients

BackgroundCytomegalovirus (CMV) causes life-threatening infections in immunocompromised host. The clinical significance of asymptomatic CMV viruria in patients receiving hematopoietic stem cell transplantation (HSCT) remains unclear. This study aims to clarify whether antiviral therapy is associated with a favorable clinical outcome.MethodsHSCT recipients whose urine was culture-positive for CMV were retrospectively reviewed and followed. Viruria episodes were divided according to whether or not antiviral therapy was used. Mortality and the estimated glomerular filtration rate (eGFR) in 2 years following CMV viruria were compared between patients with and without antiviral therapy.ResultsSixty-two episodes of culture-proven asymptomatic CMV viruria were identified in 28 HSCT recipients. Antiviral therapy was used in 35 (56.5%) and spared in 27 (43.5%) viruric episodes. Compared with the baselines, there were no significant difference in the decrements of eGFR between the two groups at the end the 1st year (4.78 vs 5.02 mL/min/1.73 m², p = 0.968) and the 2nd year (1.13 vs 7.66 mL/min/1.73 m², p = 0.276). Antiviral therapy for asymptomatic CMV viruria was also not associated with a favorable survival (p = 0.288). On the other hand, presence of CMV viremia correlated with a poorer survival (2-year mortality rate 60% vs 13.33%, p < 0.001).ConclusionAntiviral therapy for asymptomatic CMV viruria is not associated with a clear clinical benefit in HSCT recipients. Further studies may be needed to identify if specific patient populations may benefit from antiviral therapy in CMV viruria.     

Using groEL as the target for identification of Enterococcus faecium clades and 7 clinically relevant Enterococcus species

Background/Purpose

Accurate identification is important for effective treatment because Enterococcus species have talents to cope with various antibiotics either by intrinsic resistance or by acquisition of mobile genetic elements. The groEL gene is a permissive target in identification of bacteria. We aimed to develop simple assays based on groEL for identification of enterococci.

The epidemiology of non-typhoidal Salmonella gastroenteritis and Campylobacter gastroenteritis in pediatric inpatients in northern Taiwan

BackgroundCampylobacter and Non-typhoidal Salmonella (NTS) are the two most common bacterial pathogens associated with acute gastroenteritis in children. This study aims to elucidate the epidemiology of Campylobacter and NTS gastroenteritis and develop a scoring system to differentiate them.Materials and methodsThis retrospective study enrolled 886 children ≤18 years of age, hospitalized due to acute gastroenteritis with stool culture-proven Campylobacter or NTS infection from July 2012 to December 2015. Pearson's chi-square test and multivariate logistic regression were used to compare clinical manifestations and laboratory data. Receiver operating characteristic curves were plotted to evaluate the scoring system.ResultsSeasonality was found in NTS gastroenteritis from May to September, but no seasonality in Campylobacter gastroenteritis. Campylobacter jejuni and Salmonella serogroup B were the most common pathogens. The median ages were 68.2 and 18.5 months and the incidence rates of bacteremia were 0.6% and 7.1% in the Campylobacter and NTS groups, respectively. Salmonella serogroup C2 infection had the highest risk of bacteremia (OR: 5.9, 95% CI: 2.8–12.7, p < 0.001). Multivariate analysis showed significant differences in sex, age, fever, dehydration, immature WBC, CRP and Na between the two groups. A score of ≥2 points indicated Campylobacter gastroenteritis, with sensitivity 75%, specificity 77%. The positive and negative predictive values were of 73.3% and 93.9% after validation.ConclusionCampylobacter gastroenteritis is associated with older age and male sex, while NTS gastroenteritis is associated with moderate to severe dehydration and bacteremia. Salmonella serogroup C2 infection has the highest risk of bacteremia.     

Distribution of virulence genes in bacteremic methicillin-resistant Staphylococcus aureus isolates from various sources

Background/purposeMethicillin-resistant Staphylococcus aureus (MRSA) can encode proteins which directly bind bacteria to many tissues and medical devices or catheters to trigger pathogenesis. However, the relationship between genetic backgrounds and virulent factors in MRSA isolates remained incompletely understood yet.MethodsMRSA isolates were collected from blood cultures of patients with infective endocarditis, bone/joint infection, skin/soft tissue infection, or catheter-related bacteremia in hemodialysis at a tertiary medical center between 2005 and 2011. MRSA isolates were characterized by the methods of spa, multilocus sequence, and staphylococcal cassette chromosome mec (SCCmec) typing. Identification of virulence gene expression was measured by Power SYBR Green PCR Master Mix.ResultsOverall collected were 136 MRSA bacteremic isolates, including those from the cases of infective endocarditis (n = 23), bone/joint infection (n = 49), skin/soft tissue infection (n = 20), or catheter-related bacteremia in patients with acute kidney injury or end-stage renal stage receiving hemodialysis (n = 54). CC8-ST239-MRSA-SCCmec type III-spa type t037 was the most prevalent type observed in all of 136 MRSA bacteremic isolates. The prevalent genes in the group of infective endocarditis were clfA, clfB, fnbA, ebpS, eap, emp, sae, and eno; bone/joint infections clfA, emp, sae, and eno; skin/soft tissue infection eno; hemodialysis catheter-related bacteremia clfA and sae. The distribution of each gene was not statically different among four groups.ConclusionsA major MRSA lineage, CC8-ST239-MRSA-SCCmec type III-spa type t037, is noted among bacteremic MRSA isolates. No disease-specific virulent genes can be identified.     

Effectiveness of an ultraviolet-C disinfection system for reduction of healthcare-associated pathogens

BackgroundHealthcare-associated infections caused by multidrug-resistant (MDR) pathogens are significantly associated with increased mortality and morbidity. Environmental cleaning can reduce transmission of these pathogens but is often inadequate. Adjunctive methods are warranted to enhance the effectiveness of disinfection particularly in hospital settings where healthcare-associated infections are of major concern.MethodsWe conducted a study to examine the effectiveness of a mobile, automatic device, Hyper Light Disinfection Robot (model: Hyper Light P3), which utilized ultraviolet-C (UV-C) to kill MDR-Pseudomonas aeruginosa, MDR- Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), Mycobacterium abscessus and Aspergillus fumigatus. The performance of this device in disinfecting hospital rooms previously admitted by patients harboring MRSA and VRE was also assessed.ResultsExcept for VRE and M. abscessus, more than 3 log₁₀ reduction of vegetative bacteria colonies was observed after UV-C irradiation of 5 min at a distance of 3 m from the device. At the distance of 1 m, substantial and comparable reduction of colonies was observed across all tested microorganisms regardless of exposure time. The killing effect was less pronounced for A. fumigatus particularly at the distance of 2–3 m. In uncleaned hospital rooms, there was significant reduction in the number of bacteria colonies sampled from different surfaces after UV-C irradiation for 15 min.ConclusionsUV-C disinfection system was effective in killing MDR pathogens. Further study is warranted to confirm its effectiveness as an adjunctive method in disinfecting hospital environment.     

Risk factors for healthcare-associated infection caused by carbapenem-resistant Pseudomonas aeruginosa

Background/purpose

The incidence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) related healthcare-associated infection (HAI) has increased in recent year worldwide. This study is to investigate the risk factors associated with CRPA infections in a university hospital setting in Taiwan to provide more information for clinician and infection control system.