Jen Chieh Lee

Azole-resistant Aspergillus fumigatus isolates carrying TR34/L98H mutations in Taiwan

Cumulative evidence described the emergence and geographical expansion of azole‐resistant A. fumigatus associated with azole treatment failure. To investigate the status of azole resistance in A. fumigatus in Taiwan, we studied 38 A. fumigatus clinical isolates cultivated from 31 patients at two teaching hospitals from 2011 to 2014. Three isolates obtained from respiratory samples of two azole‐naïve patients with pulmonary aspergillosis were found to display multi‐azole resistance and cross resistance to agricultural azole fungicides, and all carried TR34/L98H mutations in cyp51A gene. The prevalence rates of azole resistance were 7.9% and 6.5% based on isolates and patients respectively. A phylogenetic analysis suggested genetic diversity of the TR34/L98H isolates in Taiwan, including a unique genotype distinct from strains outside Taiwan. The result underlines the emergence of such isolates in Taiwan as well, emphasising the importance of further surveillance for azole‐resistant A. fumigatus and implementation of strategies that prevent fungicide‐driven resistance selection.

Clinical impact of Clostridium difficile colonization

Clostridium difficile can cause antibiotic-associated diarrhea in hospitalized patients. Asymptomatic colonization by C. difficile is common during the neonatal period and early infancy, ranging from 21% to 48%, and in childhood. The colonization rate of C. difficile in adult hospitalized patients shows geographic variation, ranging from 4.4% to 23.2%. Asymptomatic carriage in neonates caused no further disease in many studies, whereas adult patients colonized with toxigenic C. difficile were prone to the subsequent development of C. difficile-associated diarrhea (CDAD). However, the carriage of nontoxigenic C. difficile strains appears to prevent CDAD in hamsters and humans. Risk factors for C. difficile colonization include recent hospitalization, exposure to antimicrobial agents or gastric acid-suppressing drugs (such as proton-pump inhibitors and H2 blockers), a history of CDAD or cytomegalovirus infection, the presence of an underlying illness, receipt of immunosuppressants, the presence of antibodies against toxin B, and Toll-like receptor 4 polymorphisms. Asymptomatic C. difficile carriers are associated with significant skin and environmental contamination, similar to those with CDAD, and contact isolation and hand-washing practices should therefore be employed as infection control policies for the prevention of C. difficile spread. Treating patients with asymptomatic C. difficile colonization with metronidazole or vancomycin is not suggested by the currently available evidence. In conclusion, asymptomatic C. difficile colonization may lead to skin and environmental contamination by C. difficile, but more attention should be paid to the clinical impact of those with C. difficile colonization.

Risk factors for Clostridium difficile-associated diarrhea among hospitalized adults with fecal toxigenic C. difficile colonization.

BACKGROUND Patients with toxigenic Clostridium difficile colonization (tCDC) are at risk of developing C. difficile-associated diarrhea (CDAD). However, the risk factors of hospitalized patients with tCDC developing CDAD are not clear. METHODS We conducted an 18-month prospective study at a medical ward in a district hospital in southern Taiwan. Within 48 hours of admission, weekly stool samples from asymptomatic hospitalized patients were obtained to detect fecal CDC. A polymerase chain reaction for tcdB was performed to determine toxigenic isolates. CDAD was diagnosed if the patient had diarrhea and toxigenic C. difficile present in a stool sample. RESULTS A total 483 patients with stool samples were eligible for the study. Eighty-six (17.8%) patients had tCDC after screening, of whom 14 (16.3%) developed CDAD during follow-up. Among those with tCDC, patients with subsequent CDAD were more likely to have diabetes mellitus (p = 0.01) and to have received piperacillin-tazobactam (p = 0.04), or proton-pump inhibitors (PPIs; p = 0.04) than those without developing CDAD. The variables were statistically significant as determined by multivariate analysis. However, the 60-day crude mortality rates among tCDC patients with and without subsequent development of CDAD were similar. CONCLUSION Diabetes mellitus and recent receipt of piperacillin-tazobactam or PPIs are independent risk factors for the development of CDAD among hospitalized patients with tCDC.

Risk Factors of Fecal Toxigenic or Non-Toxigenic Clostridium difficile Colonization: Impact of Toll-Like Receptor Polymorphisms and Prior Antibiotic Exposure

Background This study is to investigate the significance and risk factors of fecal toxigenic (tCdC) or non-toxigenic Clostridium difficile colonization (ntCdC) among hospitalized patients. Methods Adults admitted to medical wards in a district hospital between January 2011 and June 2012 were enrolled, and those with a history of colectomy, C. difficile fecal colonization or infection or receipt of either metronidazole or oral vancomycin within 3 months, were excluded. Stools collected within 48 hours after admission and every week during hospitalization were cultured for C. difficile. Findings Among the 441 enrolled patients, 84 (20.0%) had CdC at initial screening, including 58 (13.2%) with tCdC and 26 (6.8%) with ntCdC. Among patients with initial negative fecal screening for CdC, it took an average of 70.6 days or 66.5 days to develop tCdC or ntCdC during the study period. Finally 78 (17.7%) had tCdC and 34 (7.7%) had ntCdC. During the follow-up period, the patients with tCdC had a higher risk of CDAD (11/79, 14.1%) than those without CdC (3/328, 0.9%) and those with ntCdC (0/34, 0%) (P<0.001). In multivariate analysis, the TLR4 rs1927914 polymorphism (GG genotype) (odds ratio [OR] 4.4, 95% confidence interval [CI] 1.6–11.8, P = 0.003) and recent cefepime therapy (OR 5.3, 95% CI 2.1–13.2, P<0.001) were independently associated with tCdC, whereas recent cefuroxime (OR 11.7, 95% CI 2.3–60.2, P = 0.003) and glycopeptide therapy (OR 10.9, CI: 2.1–57.2, P = 0.005) associated with ntCdC. Conclusion The incidence of CDAD is highest in patients with tCdC and lowest in patients with ntCdC, and the TLR4 rs1927914 polymorphism GG genotype and recent cefepime therapy were independently associated with tCdC.

Proton-Pump Inhibitor Exposure Aggravates Clostridium difficile–Associated Colitis: Evidence From a Mouse Model

BACKGROUND Clostridium difficile is currently the leading cause of infectious diarrhea in hospitalized patients. In addition to the infection due to toxigenic C. difficile in the gastrointestinal tract of susceptible hosts, other predisposing factors for C. difficile infection (CDI) are identified, including advanced age, a prolonged hospital stay, and use of acid-suppressive drugs. Of note, exposure to gastric acid-reducing agents, such as H2 blockers and proton pump inhibitors (PPIs), remains a controversial risk factor, and has been associated with CDI in some studies but not in others. A mouse model of antibiotic-associated clostridial colitis was established to examine the role of PPIs for CDI. MATERIALS AND METHODS A mouse model of antibiotic-associated clostridial colitis was set up. NF-κB reporter mice were used to address the in vivo spatial and temporal inflammatory patterns of C. difficile-associated colitis. Serum levels of lipopolysaccharide and dextran-FITC were measured to reflect the barrier permeability of affected intestines. RESULTS Mice with CDI that were exposed to PPI exhibited greater losses of stool consistency and body and cecal weights than those that were not exposed to PPI. Further, more neutrophilic infiltrations, epithelial damage, and inflammatory cytokine expression were noted in colon specimens of the mice with PPI exposure. More-evident inflammatory responses were detected by in vivo imaging of NF-κB reporter mice with CDI that were exposed to PPI. Gut barrier permeability was increased to a greater extent, as reflected by higher serum levels of lipopolysaccharide and dextran-FITC in mice with CDI that were exposed to PPI. CONCLUSIONS Our mouse model demonstrates that PPI exposure increases the severity of intestinal inflammation in mice with C. difficile-associated colitis.

Doxycycline and Tigecycline: Two Friendly Drugs with a Low Association with Clostridium Difficile Infection

Clostridium difficile infection (CDI) is known to be associated with prior exposure to many classes of antibiotics. Standard therapy for CDI (i.e., metronidazole and vancomycin) is associated with high recurrence rates. Although tetracycline derivatives such as tetracycline, doxycycline or tigecycline are not the standard therapeutic choices for CDI, they may serve as an alternative or a component of combination therapy. Previous tetracycline or doxycycline usage had been shown to have less association with CDI development. Tigecycline, a broad-spectrum glycylcycline with potency against many gram-positive or gram-negative pathogens, had been successfully used to treat severe or refractory CDI. The in vitro susceptibility of C. difficile clinical isolates to tigecycline in many studies showed low minimal inhibitory concentrations. Tigecycline can suppress in vitro toxin production in both historical and hypervirulent C. difficile strains and reduce spore production in a dose-dependent manner. Tetracycline compounds such as doxycycline, minocycline, and tigecycline possess anti-inflammatory properties that are independent of their antibiotic activity and may contribute to their therapeutic effect for CDI. Although clinical data are limited, doxycycline is less likely to induce CDI, and tigecycline can be considered one of the therapeutic choices for severe or refractory CDI.

The first case of severe Clostridium difficile ribotype 027 infection in Taiwan.

The authors are grateful to Dr. Evelina Menna and Dr. Fabio Soldani (Department of Pathology and Diagnostics, Section of Infectious Diseases, Verona) and to all the nurses working at the Section of Infectious Diseases of the “G.B. Rossi” Hospital of Verona for their invaluable help in carrying out this study. The authors also acknowledge Dr. Stanley Pang (Centre d’Immunologie et des Maladies Infectieuses, E13, Paris) for its contribution.

Predominance of Clostridium difficile Ribotypes 017 and 078 among Toxigenic Clinical Isolates in Southern Taiwan.

Ribotypes and toxin genotypes of clinical C. difficile isolates in Taiwan are rarely reported. A prospective surveillance study from January 2011 to January 2013 was conducted at the medical wards of a district hospital in southern Taiwan. Of the first toxigenic isolates from 120 patients, 68 (56.7%) of 120 isolates possessed both tcdA and tcdB. Of 52 (43.3%) with tcdB and truncated tcdA (tcdA-/tcdB+), all were ribotype 017 and none had binary toxin or tcdC deletion. Eighteen (15%) toxigenic isolates harbored binary toxins (cdtA and cdtB) and all had tcdC deletion, including Δ39 (C184T) deletion (14 isolates), Δ18 in-frame deletion (3 isolates), and Δ18 (Δ117A) deletion (1 isolate). Eleven of 14 isolates with Δ39 (C184T) deletion belonged to the ribotype 078 family, including ribotype 127 (6 isolates), ribotype 126 (4 isolates), and ribotype 078 (1 isolate). Among 8 patients with consecutive C. difficile isolates, these isolates from 6 (75%) patients were identical, irrespective of the presence or absence of diarrhea, suggestive of persistent fecal carriage or colonization. In conclusion in southern Taiwan, ribotype 017 isolates with a tcdA-/tcdB+ genotype were not uncommon and of C. difficile isolates with binary toxin, the ribotype 078 family was predominant.

A Cohort Study of Adult Patients with Severe Dengue in Taiwanese Intensive Care Units: The Elderly and APTT Prolongation Matter for Prognosis

Background There was a large dengue outbreak in Taiwan in 2015, in which the ages of the affected individuals were higher than those in other countries. The aim of this study was to explore the characteristics and prognostic factors for adults with severe dengue in intensive care units (ICUs). Methods All adults admitted to ICUs with dengue virus infection (DENV) at a medical center from July 1, 2015 to December 31, 2015 were enrolled. DENV was diagnosed by the presence of serum NS1 antigen, IgM antibodies to dengue virus, or dengue virus RNA by real-time reverse transcriptase polymerase chain reaction. Demographic data, clinical features, and lab data were collected, and a multivariate Cox model was used to identify the predictive factors for in-hospital mortality. Results Seventy-five patients admitted to ICUs with laboratory-confirmed DENV were enrolled (mean age 72.3±9.3 years). The most common comorbidities included hypertension (72.0%), diabetes (43.7%), and chronic kidney disease (22.7%). The in-hospital case fatality rate (CFR) was 41.3%. The patients who died were predominantly female, had higher disease severity at ICU admission, shorter ICU/hospital stay, longer initial activated partial thromboplastin time (APTT), and higher initial serum aspartate transaminase levels. Cardiac arrest before ICU admission (hazard ratio [HR]: 6.26 [1.91–20.54]), prolonged APTT (>48 seconds; HR: 3.91 [1.69–9.07]), and the presence of acute kidney injury on admission (HR: 2.48 [1.07–5.74]), were independently associated with in-hospital fatality in the Cox multivariate analysis. Conclusion During the 2015 dengue outbreak in Taiwan, the patients with severe dengue in ICUs were characterized by old age, multiple comorbidities, and a high CFR. Organ failure (including cardiac failure, and renal failure) and coagulation disturbance (prolongation of initial APTT) were independent predictive factors for in-hospital fatality.

Clostridium difficile infections in medical intensive care units of a medical center in Southern Taiwan: Variable seasonality and disease severity

Critical patients are susceptible to Clostridium difficile infections (CDIs), which cause significant morbidity and mortality in the hospital. In Taiwan, the epidemiology of CDI in intensive care units (ICUs) is not well understood. This study was aimed to describe the incidence and the characteristics of CDI in the ICUs of a medical center in southern Taiwan. Adult patients with diarrhea but without colostomy/colectomy or laxative use were enrolled. Stool samples were collected with or without 5 ml alcohol and were plated on cycloserine-cefoxitin-fructose agar. C. difficile identification was confirmed by polymerase chain reaction. There were 1,551 patients admitted to ICUs, 1,488 screened, and 145 with diarrhea. A total of 75 patients were excluded due either to laxative use, a lack of stool samples, or refusal. Overall, 70 patients were included, and 14 (20%) were diagnosed with CDI, with an incidence of 8.8 cases per 10,000 patient-days. The incidence of CDI was found to be highest in March 2013 and lowest in the last quarter of 2013. The cases were categorized as the following: 5 severe, complicated, 5 severe, and 4 mild or moderate diseases. Among the 14 cases of CDI, the median patient age was 74 (range: 47–94) years, and the median time from admission to diarrhea onset was 16.5 (4–53) days. Eight cases received antimicrobial treatment (primarily metronidazole), and the time to diarrheal resolution was 11.5 days. Though 6 cases were left untreated, no patients died of CDI. The in-hospital mortality of CDI cases was 50%, similar to that of patients without CDI (46.4%; P = 1.0). We concluded that the overall incidence of CDI in our medical ICUs was low and there were variable seasonal incidences and disease severities of CDI.