Comparison of phylogenetic and virulence factors between Escherichia coli isolated from biliary tract infections and uropathogenic Escherichia coli.

Escherichia coli is a gram-negative intestinal commensal that can also cause various infections, including urinary tract infections, biliary tract infections, neonatal meningitis, and septicemia. Although the characteristics of uropathogenic E. coli and the mechanisms of urinary tract infection have been well studied, the genetic distinctions among E. coli isolates from different types of infections have not yet been determined. This study compared the phylogenetic and virulence factors of E. coli isolates from bacteremic biliary tract infections with those from bacteremic urinary tract infections. The phylogenetic B2 group was the most prevalent in both pathogenic groups (68 % in biliary pathogenic isolates and 85 % in uropathogenic isolates), but the frequency pattern of the phylogenetic group was different. Half of the uropathogenic isolates belonged to ST95 and ST131 (51 %). Among the biliary pathogenic isolates, ST131 was the most prevalent, while the remaining half belonged to other STs outside the four major STs. The frequency of some virulence factors, such as papC, papG2, hlyA, tcpC, fyuA, kpsMT2, sat, and traT, was lower in the biliary pathogenic isolates than in the uropathogenic isolates. The frequency of phylogenetic groups and STs in MLST differed between E. coli isolates from bacteremic biliary tract infections and urinary tract infections. Additionally, some virulence factors, including adhesion and toxin gene groups, showed lower frequencies in the biliary pathogenic group than in the uropathogenic group. Studying the differences in E. coli pathovars from different infection sites is important for developing pathovar-specific targeted therapies such as vaccine therapy.

Prospective audit and feedback implementation by a multidisciplinary antimicrobial stewardship team shortens the time to de-escalation of anti-MRSA agents.

Prospective audit and feedback (PAF) is considered an effective procedure for appropriate antibiotic use. However, its effect on the time to de-escalation is unclear. We aimed to evaluate the effect of daily PAF implementation, focusing on the time to de-escalation of anti-methicillin-resistant Staphylococcus aureus (MRSA) agents as an outcome measure. To this end, a single-center, retrospective, quasi-experimental study including patients treated with intravenous anti-MRSA agents during pre-PAF (April 1, 2014 to March 31, 2015) and post-PAF (April 1, 2015 to March 31, 2016) periods was conducted. The time to de-escalation was estimated using the Kaplan-Meier method, and Cox proportional hazard analysis was performed to assess the effect of daily PAF implementation on the time to de-escalation. Interrupted time series analysis was used to evaluate the relationship between daily PAF implementation and anti-MRSA agent utilization data converted to defined daily dose (DDD) and days of therapy (DOT) per 1,000 patient days. The median time to de-escalation was significantly shorter in the post-PAF period than in the pre-PAF period (6 days vs. 7 days, P < 0.001). According to multivariate analysis, PAF implementation was independently associated with a shorter time to de-escalation (hazard ratio [HR], 1.18; 95% confidence interval [CI], 1.02 to 1.35). There were no significant differences in hospital mortality, 30-day mortality, and length of stay between the two periods. Interrupted time series analysis showed significant reductions in the trends of DDD (trend change, -0.65; 95% CI, -1.20 to -0.11) and DOT (trend change, -0.74; 95% CI, -1.33 to -0.15) between the pre-PAF and post-PAF periods. Daily PAF implementation for patients treated with intravenous anti-MRSA agents led to a shorter time to de-escalation and lower consumption of anti-MRSA agents without worsening the clinically important outcomes.

The prevalence of the iutA and ibeA genes in Escherichia coli isolates from severe and non-severe patients with bacteremic acute biliary tract infection is significantly different.

BACKGROUND: Although Escherichia coli is the most frequently isolated microorganism in acute biliary tract infections with bacteremia, data regarding its virulence are limited. RESULTS: Information on cases of bacteremia in acute biliary tract infection in a retrospective study was collected from 2013 to 2015 at a tertiary care hospital in Japan. Factors related to the severity of infection were investigated, including patient background, phylogenetic typing, and virulence factors of E. coli, such as adhesion, invasion, toxins, and iron acquisition. In total, 72 E. coli strains were identified in 71 cases, most of which primarily belonged to the B2 phylogroup (68.1%). The presence of the iutA gene (77.3% in the non-severe group, 46.4% in the severe group, P = 0.011) and the ibeA gene (9.1% in the non-severe group, and 35.7% in the severe group, P = 0.012) was significantly associated with the severity of infection. Among the patient characteristics, diabetes mellitus with organ involvement and alkaline phosphatase were different in the severe and non-severe groups. CONCLUSIONS: We showed that bacteremic E. coli strains from acute biliary tract infections belonged to the virulent (B2) phylogroup. The prevalence of the iutA and ibeA genes between the two groups of bacteremia severity was significantly different.

Epidemiology and virulence-associated genes of Clostridioides difficile isolates and factors associated with toxin EIA results at a university hospital in Japan.

INTRODUCTION: Clostridioides difficile is one of the most important nosocomial pathogens; however, reports regarding its clinical and molecular characteristics from Japan are scarce. AIMS: We studied the multilocus sequence typing (MLST)-based epidemiology and virulence-associated genes of isolates and the clinical backgrounds of patients from whom the isolates had been recovered. METHODS: A total of 105 stool samples tested in a C. difficile toxin enzyme immune assay (EIA) were analysed at the University of Tokyo Hospital from March 2013 to July 2014. PCR for MLST and the virulence-associated genes tcdA, tcdB, cdtA, cdtB and tcdC was performed on C. difficile isolates meeting our inclusion criteria following retrospective review of medical records. EIA-positive and EIA-negative groups with toxigenic strains underwent clinical and molecular background comparison. RESULTS: The toxigenic strains ST17, ST81, ST2, ST54, ST8, ST3, ST37 and ST53 and the non-toxigenic strains ST109, ST15 and ST100 were frequently recovered. The prevalence rate of tcdA-negative ST81 and ST37, endemic in China and Korea, was higher (11.4%) than that reported in North America and Europe, and hypervirulent ST1(RT027) and ST11(RT078) strains that occur in North America and Europe were not recovered. The linkage between the EIA results and cdt A/B positivity, tcdC deletion, or tcdA variation was absent among toxigenic strains. Compared with the 38 EIA-negative cases, the 36 EIA-positive cases showed that the patients in EIA-positive cases were older and more frequently had chronic kidney disease, as well as a history of beta-lactam use and proton pump inhibitor therapy. CONCLUSION: In Japan, the prevalence rates for tcdA-negative strains are high, whereas the cdtA/B-positive strains are rare. EIA positivity is linked to older age, chronic kidney disease and the use of beta-lactams and proton pump inhibitors.

Clinical Features of Bloodstream Infections Associated with Peripheral Versus Central Venous Catheters.

INTRODUCTION: This study aimed to compare the clinical characteristics and prognoses of central venous catheter-associated bloodstream infections (CVC-BSIs) with peripheral venous catheter-associated BSIs (PVC-BSIs). METHODS: This retrospective observational study was conducted between April 2011 and March 2013 at a teaching hospital in Tokyo, Japan. Adult patients who developed CVC-BSIs and PVC-BSIs more than 2 days after admission were included. Patients with both CVC-BSIs and PVC-BSIs were excluded. Clinical characteristics of patients with CVC-BSIs and PVC-BSIs were obtained from medical records, and 30-day all-cause mortality was measured as the clinical outcome. RESULTS: We enrolled 124 PVC-BSI cases and 110 CVC-BSI cases. Median age, age-adjusted Charlson score, Sequential Organ Failure Assessment score, sex, and ward type at BSI onset did not differ significantly between the two groups. The median duration of catheter indwelling was significantly shorter in the PVC-BSI group than in the CVC-BSI group. Staphylococcus aureus and Gram-negative bacilli infections were more frequent and coagulase-negative staphylococci (CNS) and Candida spp. infections were less frequent in the PVC-BSI group than in the CVC-BSI group. The prevalence of oxacillin resistance among causative S. aureus and CNS, 30-day all-cause mortality, and appropriateness of empirical and definitive antimicrobial therapies did not differ significantly between the two groups. CONCLUSION: The pathogen species distribution varies between PVC-BSIs and CVC-BSIs. However, all-cause mortality does not differ between the two groups. PVCs are not safer than CVCs with respect to BSIs; therefore, it is necessary to use similar precautions relevant to CVC use in order to avoid unnecessary use of PVCs.

A rare case of a prostatic abscess, bacteremia and chronic granulomatous disease associated with Klebsiella pneumoniae.

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease characterized by severe recurrent infections such as pneumonia, liver and skin infections. However, prostatic abscesses are rare as only two cases have been reported thus far. We present the case of a 41-year-old patient with CGD who was admitted to the hospital with fever and subsequently, Klebsiella pneumoniae was identified on blood culture. Abdominal computed tomography revealed a prostatic abscess. He improved with intravenous antibiotics and drainage of the abscess. After he was taken off the intravenous antibiotics and started on an oral agent, he was discharged from the hospital. We confirmed a reduction in the prostatic abscess size and continued the antibiotic therapy for 52 days. A prostatic abscess is an uncommon disease being diagnosed at a median age of 49 years. Sometimes it is discovered in patients with fever of unknown origin and might be considered as an infection site of CGD patients.

Clinical and microbiological characteristics and occurrence of Klebsiella pneumoniae infection in Japan.

PURPOSE: Klebsiella pneumoniae is a pathogen that causes pneumonia and urinary tract infection. Hypervirulent K. pneumoniae strains often show hypermucoviscosity, are of the K1 or K2 serotype, and harbor the rmpA and magA genes. However, the differences in the prevalence of K. pneumoniae with these hypervirulent characteristics between the infection and colonization status are not well understood. Therefore, in this study, we compared the clinical and microbiological characteristics of K. pneumoniae isolated from urine or sputum samples of cases of infection and colonization. PATIENTS AND METHODS: This retrospective study was conducted at a tertiary care teaching hospital in Tokyo, Japan. Patients whose sputum or urine tested positive for the presence of K. pneumoniae isolates were randomly included in the study. Clinical and microbiological data were collected from medical records. RESULTS: Of the 130 cases investigated, 68 and 62 cases showed the presence of K. pneumoniae in the sputum and urine, respectively. There were 49 infection cases, including 21 in the sputum group and 28 in the urine group. The infections were not accompanied by liver abscess. Of the 130 K. pneumoniae isolates, 25 (19.2%) showed capsular serotype K1 or K2, whereas 33 (25.4%) showed hypermucoviscosity. The prevalence of virulence genes magA, allS, rmpA, mrkD, uge, kfu-BC, and wabG was 10% (all in K1), 13.1%, 16.9%, 85.4%, 79.2%, 36.9%, and 91.5%, respectively. In both the sputum and urine groups, there was no difference in the characteristics of patients with infection and those with colonization. Analysis of microbiological characteristics revealed that only rmpA was significantly more frequent in the infection cases than in the colonization/asymptomatic cases in both the sputum and urine groups. CONCLUSION: The rmpA-positive K. pneumoniae isolates were dominant in the infection cases compared with those in the colonization/asymptomatic cases, suggesting that rmpA may play a crucial role in the development of urinary tract infection and pneumonia.

Bilateral Candida endophthalmitis accompanying Candida lusitaniae bloodstream infection: A case report.

Candida lusitaniae is an uncommon cause of candidiasis in humans. Ocular manifestations of C. lusitaniae infection have not been reported. C. lusitaniae is either intrinsically resistant to amphotericin B or can acquire such resistance. We describe a case of bilateral endophthalmitis due to C. lusitaniae bloodstream infection in a liver transplant patient with rectal cancer. The patient suffered fungemia and endophthalmitis and was treated with liposomal amphotericin B. The isolate was identified as C. lusitaniae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, the system based on biochemical tests, and sequencing of the internal transcribed spacer region. The minimal inhibitory concentrations were 0.06 µg/mL for amphotericin B and 2.0 µg/mL for fluconazole. Repeat blood cultures were negative and the endophthalmitis improved following treatment with liposomal amphotericin B. However, the treatment was changed to fluconazole due to nephrotoxicity. No recurrence occurred after completion of treatment.

D-cycloserine increases the effectiveness of vancomycin against vancomycin-highly resistant Staphylococcus aureus.

Vancomycin is a widely used clinical drug to treat for infection by methicillin-resistant Staphylococcus aureus. Some patients show a weak response to vancomycin treatment. We previously reported that ß-lactams increase the susceptibility to vancomycin by vancomycin-highly resistant S. aureus (VRSA) strains obtained following repeated in vitro mutagenesis and vancomycin selection. Here we found that the susceptibility of the VRSA strains to vancomycin was remarkably increased by combined treatment with D-cycloserine. On the other hand, VRSA did not show increased susceptibility to vancomycin in combination with bacitracin, fosfomycin, erythromycin, lincomycin, gentamicin, levofloxacin or nisin. Furthermore, in an in vivo infection model with silkworms, combined treatment with vancomycin and D-cycloserine exhibited therapeutic effects, whereas treatment with each compound alone did not. These findings suggest that combined treatment with vancomycin and D-cycloserine could be therapeutically effective against infectious diseases caused by VRSA.

Synergistic effects of vancomycin and ß-lactams against vancomycin highly resistant Staphylococcus aureus.

We previously reported isolating vancomycin (VAN) highly resistant Staphylococcus aureus (VRSA) strains from clinical methicillin-resistant S. aureus strains by repeating steps of in vitro mutagenesis and VAN selection. Here we describe that the in vitro susceptibility of these VRSA strains to VAN was markedly increased by combined treatment with ß-lactams such as ceftriaxone and oxacillin. Furthermore, in an in vivo silkworm infection model with VRSA, a combination of VAN and ceftriaxone exhibited therapeutic effects, whereas a combination of VAN and oxacillin did not. These findings suggest that combining VAN with an appropriate ß-lactam, such as ceftriaxone, is therapeutically effective against infectious diseases caused by VRSA.

Catheter-related bloodstream infection caused by Kodamaea ohmeri: A case report and literature review.

Kodamaea ohmeri is a rare yeast pathogen that has recently emerged as an important cause of fungemia in immunocompromised patients. However, appropriate therapy for this infection remains unclear. We report a case of catheter-related blood stream infection caused by K. ohmeri in a 58-year-old patient who improved after removal of the central venous catheter and administration of micafungin. Considering the antibiotic susceptibility of this pathogen and reviewing literature, echinocandins may be the first choice for an empiric therapy for this pathogen.

Scedosporium prolificans Endocarditis: Case Report and Literature Review.

Scedosporium prolificans, a hyaline filamentous fungus, is widely distributed in the environment and is currently an emerging human pathogen, especially among immunocompromised patients. However, S. prolificans endocarditis is rare. We herein report a case of S. prolificans endocarditis in a 64-year-old patient with breast cancer in complete remission for 30 years after chemotherapy and radiation treatment who was not cured. Susceptibility testing showed resistance to all antifungal drugs, except echinocandin. A review of the literature revealed 10 cases of S. prolificans endocarditis; of these, only one involved an immunocompetent host with no risk factors and only two patients survived. In order to improve the mortality rate, it is necessary to establish rapid diagnostic methods and efficient therapeutic approaches.

Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis.

The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 µg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.

Clinical characteristics and antimicrobial susceptibility of Bacillus cereus blood stream infections.

BACKGROUND: Bacillus cereus is one of the pathogens causing nosocomial bloodstream infections (BSIs). However, few reports have documented the antimicrobial susceptibility and clinical characteristics of Bacillus cereus BSI and the importance of empirical therapy. The aim of this study was to investigate the clinical characteristics and antimicrobial susceptibility of B. cereus isolates from patients with BSI and to analyze the impact of appropriate empirical therapy on the outcome of patients with B. cereus BSI. METHODS: All adult cases of bacteremia between April 2003 and March 2012 in a teaching hospital in Tokyo, Japan were reviewed retrospectively. Clinical data were collected from the patients' medical records and charts. Antimicrobial susceptibility testing was performed by broth microdilution method. The patients with B. cereus BSI were divided into an appropriate empirical therapy group and an inappropriate empirical therapy group. The primary outcome was all-cause mortality at 4 weeks after the start of BSI. The secondary outcome was early defervescence within 2 days after starting empirical therapy. RESULTS: There were 29 B. cereus bloodstream infection cases. No vancomycin, gentamicin, and imipenem-resistant isolates were found. However, 65.5 % were resistant to clindamycin and 10.3 % were resistant to levofloxacin. The main etiology was venous catheter-related (69 %). All-cause mortality at 4 weeks was not significantly different between the appropriate empirical therapy group (9 cases) and the inappropriate group (20 cases) in this study. However, early defervescence within 2 days after starting empirical therapy was significantly different (p = 0.032). CONCLUSIONS: The BSI of B. cereus is mostly caused by venous catheter-related infections. Appropriate empirical therapy is important to achieve early clinical resolution in B. cereus BSI. Vancomycin is one of the appropriate selections of empirical therapy for B. cereus BSI.

A Case of Liver Abscess with Desulfovibrio desulfuricans Bacteremia.

Desulfovibrio spp. are gram-negative, sulfate-reducing, and anaerobic bacteria found in the digestive tract of humans. Because Desulfovibrio spp. are infrequent causative agents of infectious diseases and are difficult to isolate and to identify from clinical specimens, the appropriate antibiotic therapy to infection with Desulfovibrio spp. has not been determined. We report the first case of liver abscess with bacteremia due to Desulfovibrio desulfuricans to show the clinical presentation and treatment. The patient was successfully treated with intravenous piperacillin-tazobactam and oral amoxicillin-clavulanic acid.

Recurrent cerebral aneurysm formation and rupture within a short period due to invasive aspergillosis of the nasal sinus; pathological analysis of the catastrophic clinical course.

Destructive infiltration of invasive fungal sinusitis can easily occur into the central nervous system (CNS). Cerebral aneurysms associated with fungal infection are highly vulnerable to rupture, and can frequently and rapidly take a serious clinical course. We experienced a patient who twice developed cerebral aneurysm followed by rupture due to invasive fugal sinusitis. This 77-year-old man was admitted for progressive bilateral visual disturbance, which was initially treated as idiopathic hypertrophic pachymeningitis. The patient subsequently suffered subarachnoid hemorrhage (SAH) twice in only 12 days. Both SAH originated from different newly formed cerebral aneurysms. Trapping was performed for both ruptured aneurysms. Pathological examination of the resected aneurysms indicated the presence of fungi determined to be Aspergillus. This Aspergillus infection was also discovered inside the frontal sinus by endoscopic biopsy, so a regimen of antifungal agents was instituted. Prolonged antifungal therapy caused renal impairment, which ultimately led to the patient's death. Autopsy detected no mycotic infiltration of the major cerebral arteries, except for the 2 ruptured cerebral aneurysms. However, prolonged mycosis of the CNS, such as in the deep part in the falx cerebri and in the small veins proximal to the tentorium cerebelli, was observed, indicating that mycosis invading the cranium is refractory even to long-term administration of antifungal agents. The present case strongly suggests that urgent and proactive definitive diagnosis is essential to successfully treat invasive paranasal sinus aspergillosis. If infiltration of the CNS is suspected, early surgical resection and antifungal therapy must be initiated immediately.

Changes in the mean platelet volume levels after bloodstream infection have prognostic value.

OBJECTIVE: Thrombocytopenia is frequently observed during bloodstream infection (BSI); however, little is known about the trends in platelet size during BSI. The aim of this study was to investigate trends in platelet indices during BSI and to determine the relationship between the mean platelet volume (MPV) levels and the prognosis of BSI patients. METHODS: We conducted a four-year retrospective study to assess the trends in the platelet indices and the clinical features of BSI. We enrolled 350 patients with positive blood cultures and measured the platelet indices during five periods: 30 to seven days before onset (1st period); within one day of onset (2nd period); three to five days after onset (3rd period); seven to 10 days after onset (4th period); and 14 to 19 days after onset (5th period). The end point was defined as 30-day mortality. RESULTS: Among the BSI patients, the average platelet count decreased during BSI (29.4 *10(9)/L to 24.0 *10(9)/L, p<0.001), while the average MPV level increased (7.33 fL to 7.89 fL, p<0.001). The degree of MPV elevation in the nonsurvivors (n=25) was lower than that observed in the survivors (n=325) between the 1st and 2nd periods (0.00 fL vs. 0.35 fL, p=0.006), whereas between the 2nd and 3rd periods, the degree of MPV elevation in the nonsurvivors was higher than that observed in the survivors (0.74 fL vs. 0.19 fL, p=0.03). MPV elevation after BSI was identified to be a negative prognostic factor for BSI (odds ratio: 1.82; 95% confidence interval: 1.00-3.32; p=0.027). CONCLUSION: Changes in the MPV levels after BSI may therefore be a useful prognostic marker for BSI.

A case of Schizophyllum commune sinusitis following unrelated cord blood transplantation for acute lymphoblastic leukemia.

Schizophyllum commune is a globally distributed basidiomycete fungus that is known as a rare cause of sinusitis, for which no prompt treatment has been established. We describe the first report of S. commune sinusitis following unrelated cord blood transplantation for acute lymphoblastic leukemia. Thirteen days after transplantation, a 23-year-old female developed maxillary and ethmoid sinusitis. The sinusitis was antimicrobial-resistant, and the sinus aspirate culture revealed white wooly mold, which was identified as S. commune by nucleotide sequencing. The patient was successfully treated with intravenous administration of liposomal amphotericin B for 2 months, followed by oral voriconazole. This report suggests the effectiveness of liposomal amphotericin B and voriconazole for S. commune infection in immunocompromised patients. Given the difficulty in distinguishing S. commune infection from aspergillosis by standard culture methods, the incidence of S. commune infection following allogeneic hematopoietic stem cell transplantation may be underestimated. Nucleotide sequencing may be useful in the diagnosis of S. commune infection.

Two cases of bacteremia caused by Leptotrichia trevisanii in patients with febrile neutropenia.

We present two cases of bacteremia caused by Leptotrichia trevisanii: a 12-year-old girl with recurrent myeloid leukemia of the mandible and a 66-year-old man with esophageal carcinoma. As this filamentous bacillus showed indefinite Gram staining and the identification based on biochemical enzymatic reactions was not definitive, identification required 16s rRNA analysis. For this organism, drug sensitivity testing showed susceptiblity to each ß-lactam antibiotics and clindamycin, but resistance to fluoroquinolone and erythromycin. This filamentous bacillus needs careful identification and appropriate antibiotic treatment.