Ting-Shu Wu

Severe Cutaneous Adverse Reactions Related to Systemic Antibiotics

BACKGROUND Systemic antibiotics are a major cause of severe cutaneous adverse reactions (SCARs). The selection of alternative antibiotics and management for SCARs patients with underlying infections can be challenging. METHODS We retrospectively analyzed 74 cases of SCARs, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP), related to use of systemic antibiotics in Taiwan from January 2006 to January 2012. We analyzed the causative antibiotics, clinical features, organ involvements, and mortality. We also assessed patient tolerability to alternative antibiotics after the development of antibiotic-related SCARs. RESULTS The most common causes of SCARs were penicillins and cephalosporins for SJS/TEN and AGEP; glycopeptides for DRESS. Fatality was more frequent in the SJS/TEN group. In patients with SJS/TEN, higher mortality was associated with old age and underlying sepsis before the development of SCARs. The majority of patients with penicillin- or cephalosporin-related SCARs were able to tolerate quinolones, glycopeptides, and carbapenems. CONCLUSIONS Complicated underlying conditions and infections may increase mortality in patients with antibiotic-related SCARs. The selection of structurally different alternative drugs is important to avoid recurrence.

Activation of an NLRP3 Inflammasome Restricts Mycobacterium kansasii Infection

Mycobacterium kansasii has emerged as an important nontuberculous mycobacterium pathogen, whose incidence and prevalence have been increasing in the last decade. M. kansasii can cause pulmonary tuberculosis clinically and radiographically indistinguishable from that caused by Mycobacterium tuberculosis infection. Unlike the widely-studied M. tuberculosis, little is known about the innate immune response against M. kansasii infection. Although inflammasome activation plays an important role in host defense against bacterial infection, its role against atypical mycobacteria remains poorly understood. In this report, the role of inflammasome activity in THP-1 macrophages against M. kansasii infection was studied. Results indicated that viable, but not heat-killed, M. kansasii induced caspase-1-dependent IL-1β secretion in macrophages. The underlying mechanism was found to be through activation of an inflammasome containing the NLR (Nod-like receptor) family member NLRP3 and the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD). Further, potassium efflux, lysosomal acidification, ROS production and cathepsin B release played a role in M. kansasii-induced inflammasome activation. Finally, the secreted IL-1β derived from caspase-1 activation was shown to restrict intracellular M. kansasii. These findings demonstrate a biological role for the NLRP3 inflammasome in host defense against M. kansasii.

NK cells kill mycobacteria directly by releasing perforin and granulysin

Although the mechanisms underlying the cytotoxic effect of NK cells on tumor cells and intracellular bacteria have been studied extensively, it remains unclear how these cells kill extracellular bacterial pathogens. In this study, we examine how human NK cells kill Mycobacterium kansasii and M.tb. The underlying mechanism is contact dependent and requires two cytolytic proteins: perforin and granulysin. Mycobacteria induce enhanced expression of the cytolytic proteins via activation of the NKG2D/NCR cell‐surface receptors and intracellular signaling pathways involving ERK, JNK, and p38 MAPKs. These results suggest that NK cells use similar cellular mechanisms to kill both bacterial pathogens and target host cells. This report reveals a novel role for NK cells, perforin, and granulysin in killing mycobacteria and highlights a potential alternative defense mechanism that the immune system can use against mycobacterial infection.

Resveratrol induces apoptosis of human nasopharyngeal carcinoma cells via activation of multiple apoptotic pathways

Resveratrol, a naturally occurring dietary compound with chemopreventive properties has been reported to trigger a variety of cancer cell types to apoptosis. Whether resveratrol shows any activity on human nasopharyngeal carcinoma (NPC) cells remained to be determined. The aim of this study was to investigate the effect and mechanism of resveratrol on human NPC cells. Treatment of resveratrol resulted in significant decrease in cell viability of NPC cell lines in a dose‐ and time‐dependent manner. A dose‐dependent apoptotic cell death was also measured by flow cytometery analysis. Molecular mechanistic studies of apoptosis unraveled resveratrol treatment resulted in a significant loss of mitochondrial transmembrane potential, release of cytochrome c, enhanced expression of Fas ligand (FasL), and suppression of glucose‐regulated protein 78 kDa (GRP78). These were followed by activation of caspases‐9, ‐8, ‐4, and ‐3, subsequently leading to DNA fragmentation and cell apoptosis. Furthermore, up‐regulation of proapoptotic Bax and down‐regulation of antiapoptotic Bcl‐2 protein were also observed. Taken together, resveratrol induces apoptosis in human NPC cells through regulation of multiple apoptotic pathways, including death receptor, mitochondria, and endoplasmic reticulum (ER) stress. Resveratrol can be developed as an effective compound for human NPC treatment. J. Cell. Physiol. 226: 720–728, 2011.

Rapid Identification of Mycobacteria from Smear-Positive Sputum Samples by Nested PCR-Restriction Fragment Length Polymorphism Analysis

ABSTRACT The rapid identification of mycobacteria from smear-positive sputum samples is an important clinical issue. Furthermore, the availability of a cheap, technically simple, and accurate method also would benefit mycobacterial laboratories in developing countries. In the present study, we aimed to develop an assay allowing the identification of the Mycobacterium tuberculosis complex (MTBC) and other frequently isolated nontuberculous mycobacteria (NTM) directly from smear-positive sputum samples. A nested PCR-restriction fragment length polymorphism analysis (nested-PRA) assay that focuses on the analysis of the hsp65 gene was developed and evaluated for its efficiency compared to that of traditional culture methods and 16S rRNA gene sequencing identification. A total of 204 smear-positive and culture-positive sputum specimens were prospectively collected for analysis between November 2005 and May 2006. The samples were classified according to an acid-fast bacillus (AFB) staining scale as rare/1+, 2+, or 3+. The results of the nested-PRA showed that the identification rate for AFB 3+, AFB 2+, and AFB rare/1+ samples was 100, 95, and 53%, respectively, and that the overall identification rate was 89%. All positive results by the nested-PRA method agreed with the results by culture and 16S rRNA gene sequence analysis. The nested-PRA appears to have clinical applicability when used for the direct identification of mycobacterial organisms (both MTBC and NTM) that are present in smear-positive sputum samples, especially for countries in which MTBC is endemic.

Molecular signature of clinical severity in recovering patients with severe acute respiratory syndrome coronavirus (SARS-CoV)

BackgroundSevere acute respiratory syndrome (SARS), a recent epidemic human disease, is caused by a novel coronavirus (SARS-CoV). First reported in Asia, SARS quickly spread worldwide through international travelling. As of July 2003, the World Health Organization reported a total of 8,437 people afflicted with SARS with a 9.6% mortality rate. Although immunopathological damages may account for the severity of respiratory distress, little is known about how the genome-wide gene expression of the host changes under the attack of SARS-CoV.ResultsBased on changes in gene expression of peripheral blood, we identified 52 signature genes that accurately discriminated acute SARS patients from non-SARS controls. While a general suppression of gene expression predominated in SARS-infected blood, several genes including those involved in innate immunity, such as defensins and eosinophil-derived neurotoxin, were upregulated. Instead of employing clustering methods, we ranked the severity of recovering SARS patients by generalized associate plots (GAP) according to the expression profiles of 52 signature genes. Through this method, we discovered a smooth transition pattern of severity from normal controls to acute SARS patients. The rank of SARS severity was significantly correlated with the recovery period (in days) and with the clinical pulmonary infection score.ConclusionThe use of the GAP approach has proved useful in analyzing the complexity and continuity of biological systems. The severity rank derived from the global expression profile of significantly regulated genes in patients may be useful for further elucidating the pathophysiology of their disease.

Fish Tank Granuloma Caused by Mycobacterium marinum

Introduction Mycobacterium marinum causes skin and soft tissue, bone and joint, and rare disseminated infections. In this study, we aimed to investigate the relationship between treatment outcome and antimicrobial susceptibility patterns. A total of 27 patients with M. marinum infections were enrolled. Methods Data on clinical characteristics and therapeutic methods were collected and analyzed. We also determined the minimum inhibitory concentrations of 7 antibiotics against 30 isolates from these patients. Results Twenty-seven patients received antimycobacterial agents with or without surgical debridement. Eighteen patients were cured, 8 failed to respond to treatment, and one was lost to follow-up. The duration of clarithromycin (147 vs. 28; p = 0.0297), and rifampicin (201 vs. 91; p = 0.0266) treatment in the cured patients was longer than that in the others. Surgical debridement was performed in 10 out of the 18 cured patients, and in 1 of another group (p = 0.0417). All the 30 isolates were susceptible to clarithromycin, amikacin, and linezolid; 29 (96.7%) were susceptible to ethambutol; 28 (93.3%) were susceptible to sulfamethoxazole; and 26 (86.7%) were susceptible to rifampicin. However, only 1 (3.3%) isolate was susceptible to doxycycline. Discussion Early diagnosis of the infection and appropriate antimicrobial therapy with surgical debridement are the mainstays of successful treatment. Clarithromycin and rifampin are supposed to be more effective agents.

Clinical manifestations, antibiotic susceptibility and molecular analysis of Mycobacterium kansasii isolates from a university hospital in Taiwan

OBJECTIVES Mycobacterium kansasii causes a variety of infections. Although previous reports on the prognosis of antimicrobial therapy have been mostly satisfactory, problems involving treatment failure or relapse have been encountered. The purpose of this study was to establish a relationship between the clinical treatment outcomes of M. kansasii infections and bacterial drug susceptibility, and their clonality. METHODS A total of 37 M. kansasii clinical isolates and clinical information on 34 patients were retrospectively collected in a tertiary medical centre in Taiwan. Bacterial drug susceptibility was determined by the microdilution method. The phylogenetic relationship was analysed by PFGE analysis. RESULTS Results of PFGE typing revealed a major cluster (cluster I) and eight other divergent patterns. Two/three strains leading to treatment failure were also multidrug resistant and belonged to cluster I. CONCLUSIONS A relationship between high drug resistance and genetic relatedness of some M. kansasii strains was established. This was associated with clinical treatment failure.

Change in Demographic Picture and Increase of Drug Resistance in Pulmonary Tuberculosis in a 10-Year Interval in Taiwan

AbstractBackground: This study was designed to compare the change in demographics, medical characteristics and drug resistance of patients with active pulmonary tuberculosis (TB) betwen two time periods within a 10-year interval. Patients and Methods: We retrospectively reviewed the clinical records and chest radiographs of 1,826 patients with active pulmonary TB for two time periods from 1992–1996 (n = 884) and 1982–1986 (n = 942). Results: The mean age was significantly higher and there were significantly more female patients in the 1992–1996 period than in the 1982–1986 period. In the 1992–1996 period, there were significantly fewer patients with the main complaints of cough, fever and body weight loss at the time of diagnosis but significantly more patients who had diabetes mellitus, obstructive airway disease, cancer other than lung cancer or who were on corticosteroid therapy. During the 1992–1996 period, single drug resistance against isoniazid (INH), rifampin (RIF) and streptomycin increased by 0.5%, 3% and 0.7%, respectively. Multiple drug resistance against both INH and RIF increased by 2% in the 1992–1996 period. A history of pulmonary TB and extensive pulmonary involvement were two significant factors for drug resistance against INH, RIF or ethambutol (EMB). Conclusion: In the 1992–1996 period, the mean age of patients and number of female patients significantly increased. There were more patients with diabetes mellitus, obstructive airway diseases, cancer other than lung cancer and prior steroid therapy but fewer patients presenting with classic clinical symptoms of TB. In consideration of the high prevalence and increasing rate of single and multiple drug resistance, we recommend an initial four-drug regimen (INH, RIF, EMB, pyrazinamide) for the treatment of pulmonary TB in Taiwan.

Rapid identification of Mycobacterium avium clinical isolates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

BACKGROUND Rapid and accurate discrimination of Mycobacterium avium from other mycobacteria is essential for appropriate therapeutic management and timely intervention for infection control. However, routine clinical identification methods for M. avium are both time consuming and labor intensive. In the present study, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify specific cellular protein pattern for rapid identification of M. avium isolates. METHODS A total of 40 clinically relevant Mycobacterium strains comprising 13 distinct species were enrolled for the MALDI-TOF MS identification. A 10-minute extraction-free examination procedure was set up to obtain mass spectral fingerprints from whole bacterial cells. RESULTS The characteristic mass spectral peak patterns in the m/z (mass/charge ratio) range of 5-20 kDa can be obtained within 10 minutes. The species-specific mass spectra for M. avium is identified and can be differentiated from as Mycobacterium strains. This technique shortens and simplifies the identification procedure of MALDI-TOF MS and may further extend the mycobacterial MALDI-TOF MS database. CONCLUSION Simplicity and rapidity of identification procedures make MALDI-TOF MS an attractive platform in routine identification of mycobacteria. MALDI-TOF MS is applicable for rapid discrimination of M. avium from other Mycobacterium species, and shows its potential for clinical application.