Cheng-Yi Liu

A 5-Year Study of the Seroepidemiology of Klebsiella pneumoniae: High Prevalence of Capsular Serotype K1 in Taiwan and Implication for Vaccine Efficacy

Seroepidemiology of Klebsiella pneumoniae was determined for 1000 nonrepetitive K. pneumoniae isolates collected by a medical center in Taiwan during 1993-1997. Of these, 630 isolates (63%) were from community-acquired infections; the rest were from hospital-acquired infections. The isolates were serotyped according to capsular antigen by countercurrent immunoelectrophoresis. About 77% were typeable. Serotypes K1 and K2 accounted for 21.7% and 9.3% of the isolates, respectively, followed by K57 (5.1%), K54 (4.2%), K21 (3. 3%), and K16 (3%). The frequency of serotype K1 among bacteremic isolates (30.8%) far exceeded that reported by other investigators worldwide. Molecular typing of random K1 isolates by pulsed-field gel electrophoresis revealed several different pulsotypes, suggesting a nonclonal spread. This study indicates that a Klebsiella vaccine developed in Europe is not optimal for use in Taiwan because it does not contain the most predominant serotypes-K1, K54, and K57.

Risk factors and mortality in patients with nosocomial Staphylococcus aureus bacteremia

BACKGROUND Infections due to methicillin-resistant Staphylococcus aureus have become increasingly common in hospitals worldwide. S aureus continues to be a cause of nosocomial bacteremia. METHODS We analyzed the clinical significance (mortality) of MRSA and methicillin-susceptible S aureus bacteremia in a retrospective cohort study in a 2900-bed tertiary referral medical center. Survival and logistic regression analyses were used to determine the risk factors and prognostic factors of mortality. RESULTS During the 15-year period, 1148 patients were diagnosed with nosocomial S aureus bacteremia. After controlling potential risk factors for MRSA bacteremia on logistic regression analysis, service, admission days prior to bacteremia, age, mechanical ventilator, and central venous catheter (CVC) were independent risk factors for MRSA. The crude mortality rate of S aureus bacteremia was 44.1%. The difference between the mortality rates of MRSA (49.8%) and MSSA bacteremia (27.6%) was 22.2% (P < .001). Upon logistic regression analysis, the mortality with MRSA bacteremia was revealed to be 1.78 times higher than MSSA (P < .001). The other predicted prognostic factors included age, neoplasms, duration of hospital stay after bacteremia, presence of mechanical ventilator, and use of CVC. CONCLUSIONS Resistance to methicillin was an important independent prognostic factor for patients with S aureus bacteremia.

Clinical and microbiological characteristics of Chryseobacterium indologenes bacteremia.

BACKGROUND/PURPOSE Reports detailing bacteremia caused by Chryseobacterium indologenes remain limited, with most cases reported in Taiwan. The clinical significance of C. indologenes has not been fully established. This retrospective study investigated the clinical features and antimicrobial susceptibility of C. indologenes bacteremia. METHODS Patients with C. indologenes bacteremia were identified at a medical center/teaching hospital in northern Taiwan between January 1, 2004 and January 31, 2008. Clinical features and the antimicrobial susceptibilities of these patients were analyzed. RESULTS Sixteen isolates of C. indologenes from 16 episodes in 16 patients were identified, with all patients having underlying diseases. Two patients (12.5%) had polymicrobial bacteremia. The portal of bacteremia was not determined in most cases. Other clinical syndromes included catheter-related bacteremia, urinary tract infection and peritonitis. The majority of patients had undergone invasive procedures. Other associated conditions included immunosuppression, neutropenia and prolonged use of antibiotics. Only three patients were treated with appropriate antibiotics according to minimum inhibitory concentrations. The susceptibilities of isolates to trimethoprim-sulfamethoxazole (75.0%), levofloxacin (62.5%), piperacillin-tazobactam (50.0%), ciprofloxacin (43.75%) and cefepime (12.5%) were variable and the bacteremia-related mortality rate was 6.25%. CONCLUSION C. indologenes isolates are resistant to multiple antibiotics, with newer fluoroquinolones and trimethoprim-sulfamethoxazole possibly representing the most appropriate antimicrobial agents to treat infections caused by this pathogen. However, the pathogenicity and factors of virulence for C. indologenes remain unclear, with our study revealing favorable outcomes of C. indologenes bacteremia. Epidemiological surveillance of this organism in Taiwan and extensive worldwide surveillance programs are required.

Up-Regulation of Fas Ligand Expression by Human Cytomegalovirus Immediate-Early Gene Product 2: A Novel Mechanism in Cytomegalovirus-Induced Apoptosis in Human Retina

Human CMV (HCMV) is an important pathogen that causes widespread diseases in immunocompromised individuals. Among the opportunistic HCMV infections, HCMV retinitis is most common in transplant recipients and AIDS patients. It often leads to blindness if left untreated. The question as to how HCMV infection causes retinal pathogenesis remains unresolved. Here, we report that viral immediate-early gene product 2 (IE2), but not IE1, up-regulates the Fas ligand (FasL) expression in HCMV-infected human retinal pigment epithelium cells. Increased secretion of FasL from virally infected cells into cultured medium was observed upon HCMV infection. The capability of such cell-free medium to induce apoptosis of Fas (CD95)-expressing Jurkat cells further implies that Fas-FasL interaction might mediate cell death in the lesion of HCMV retinitis. To support this idea, we observed augmented soluble FasL levels in vitreous from AIDS patients with HCMV retinitis as compared with that from AIDS patients without HCMV infection. In addition, by in situ hybridization and immunohistochemistry, we detected enhanced signals of FasL, the existence of viral IE Ags and apoptotic cells at the same sites in the lesion of HCMV-infected retina. These results strongly suggest that IE2 induction of FasL expression in human retina might be an important event that takes place in the early stage of infection and finally leads to visual loss in individuals affiliated with HCMV retinitis.

Brevundimonas bacteremia: Two case reports and literature review

Brevundimonas spp. are infrequently isolated from clinical samples, including blood. The vast majority of reported cases have underlying diseases. Whether these microorganisms represent true pathogens of human disease in all populations remains to be explored. We present 2 cases of bloodstream infection caused by Brevundimonas sp., with one of these individuals immunocompetent, and discuss the possible role of these organisms in different patient populations.

Clinical and microbiological analysis of Elizabethkingia meningoseptica bacteremia in adult patients in Taiwan.

A limited number of reports have documented bacteremia caused by Elizabethkingia meningoseptica (Chryseobacterium meningosepticum) in adults. Most cases have occurred in Taiwan. This study investigated the clinical features and risk factors for mortality from E. meningoseptica bacteremia and the antimicrobial susceptibilities of the isolates. Patients with E. meningoseptica bacteremia were retrospectively analyzed at a medical center/teaching hospital in northern Taiwan over a 3-y period. We analyzed clinical features and outcomes of patients and antimicrobial susceptibilities and pulsed-field gel electrophoresis (PFGE) results of the isolates. 28 patients had nosocomial bacteremia and 4 patients had healthcare associated bacteremia. The isolates exhibited variable susceptibilities to levofloxacin, ciprofloxacin, piperacillin-tazobactam, tigecycline, and trimethoprim-sulfamethoxazole. PFGE demonstrated that most isolates were epidemiologically unrelated. The 28-d mortality rate was 41%. Multivariate analysis indicated that shock and use of inappropriate antibiotics were independent risk factors for mortality. In conclusion, nosocomial bloodstream infection due to E. meningoseptica is an increasing problem in Taiwan. Our study indicates that patients with E. meningoseptica bacteremia face poor prognoses, with shock and use of inappropriate antibiotics as the main risk factors for mortality. Further clinical study is needed to establish the optimal therapy for E. meningoseptica bacteremia.

Clinical features and outcomes of severe acute respiratory syndrome and predictive factors for acute respiratory distress syndrome.

Background: Severe acute respiratory syndrome (SARS) is an emerging infectious disease, and indeed, the SARS epidemic in Taiwan from March to July 2003 had a great impact. This study depicts the clinical characteristics and short‐term outcomes of patients with SARS treated at Taipei Veterans General Hospital; potential predictive factors for acute respiratory distress syndrome (ARDS) are also analyzed. Methods: This study retrospectively analyzed data for 67 SARS patients, who were grouped according to whether or not ARDS developed during the clinical course of SARS. Results: There were 32 males (mean age, 50.3 years; range, 20–75 years) and 35 females (mean age, 51.1 years; range, 23–86 years). Twenty‐five patients (37.3%) were health care workers. At admission, 50 patients (74.6%) had abnormal chest radiographs, and all patients developed pulmonary infiltrates during the following week. During hospitalization, lymphopenia was found in 57 patients (85.1%); and elevated levels of lactate dehydrogenase (LDH; n = 55; 83.3%), C‐reactive protein (n = 55; 83.3%), aminotransferases (n = 44; 65.7%), and creatine kinase (n = 14; 20.9%) were also noted. ARDS developed in 33 patients (49.3%), who were generally older than the patients in whom ARDS did not develop, male, non‐health care workers, and who generally had dyspnea at the time of diagnosis, and a history of diabetes mellitus, hypertension or cerebrovascular accident. Patients with, versus those without, ARDS also tended to present with more severe lymphopenia and leukocytosis, and with higher levels of LDH and aspartate aminotransferase. The overall mortality rate was 31.3% (21/67), whereas the rate for patients who developed ARDS was 63.6% (21/33). Multivariate analyses showed that age greater than 65 years (odds ratio, OR, 10.6; 95% confidence interval, CI, 2.1–54.1), pre‐existing diabetes mellitus (OR, 13.7; 95% CI, 1.3–146.9), and elevated levels of LDH (OR, 8.4; 95% CI, 1.9–36.9) at admission, were independent predictors of ARDS. Conclusion: The clinical manifestations of SARS showed high variability, and were related to the underlying health status of individual patients. Importantly, the development of ARDS was associated with significant mortality, despite aggressive therapy.

Successful Treatment of Metastatic Endophthalmitis

Endophthalmitis is a well-recognized complication of intraocular surgery, penetrating ocular trauma and systemic infection. Metastatic bacterial endophthalmitis is rare. However, once it happens, the visual outcome is very poor. In order to prevent visual damage, early diagnosis and treatment is essential. Due to the blood-ocular barrier, intravitreal drug concentrations are low after systemic administration. Strong antibiotics with good penetration into the vitrous humor are needed to obtain adequate bactericidal concentrations. We report two cases with liver abscess complicated by septic events to the eye. One was uveitis, and the other was endophthalmitis. They were diagnosed early and were successfully treated with parenteral ceftriaxone and good vision was preserved.

Clinical significance of Acinetobacter species isolated from cerebrospinal fluid

Medical records of 54 patients whose cerebrospinal fluid (CSF) cultures were positive for Acinetobacter were retrospectively reviewed. In 34 (63.0%) patients, the Acinetobacter isolates were clinically insignificant. In the other 20 (37.0%) patients, presence of the organism was regarded as clinically significant and specific antimicrobial therapy was administered. Patients with clinically significant Acinetobacter in CSF more frequently resided in intensive care units (p = 0.011), had intracerebral hemorrhage (p = 0.012) or previous CNS infection (p = 0.003), had prior antibiotic exposure (p = 0.011), and had undergone neurosurgical procedures (p = 0.003). Their CSF was characteristic of neutrophilic pleocytosis, an elevated protein level, and a low CSF-to-serum glucose ratio. Apart from fever, no significant statistical differences existed in individual clinical symptoms and signs between the 2 groups of patients, while a combination of symptoms efficiently differentiated clinically significant and insignificant Acinetobacter. The finding of multiple CSF specimens positive for Acinetobacter was highly suggestive of an active CNS infection (p<0.001). The high ratio of clinically insignificant Acinetobacter CSF isolates highlights the importance of careful judgment when the organism is cultured from CSF. Antimicrobial therapy must be initiated promptly in patients with identified risk factors, while unnecessary treatment should be avoided in those without them.

Clostridium perfringens septicemia with massive hemolysis.

Massive hemolysis with acute renal failure occurred in a previously healthy 69-year-old patient as a complication of Clostridium perfringens septicemia secondary to gall bladder empyema. To our knowledge, this is one of the few patients with C. perfringens septicemia and massive intravascular hemolysis who survived the episode and regained a normal renal function.