Etiology of community acquired pneumonia among adult patients requiring hospitalization in Taiwan.

BACKGROUND: There has not been a comprehensive multi-center study investigating the microbial profile of community acquired pneumonia (CAP) in Taiwan. METHODS: A prospective study of adult CAP patients requiring hospitalization between December 2001 and April 2002 was carried out in 13 hospitals in Taiwan. Etiology was determined based on laboratory data from blood and sputum cultures plus serology from paired serum and urine antigen detection tests. RESULTS: Etiology was assigned to 99 (58.9%) of the 168 patients having the most complete data for etiology determination, with mixed infection in 21 (12.5%) patients. More than half (51.8%) of the patients were>60 years and 63.7% of the patients were males. The most common etiologic agent was Streptococcus pneumoniae (40, 23.8%), the majority (60%, 24 cases) of which was detected by positive urine antigen test. Other common agents included Mycoplasma pneumoniae (24, 14.3%), Chlamydia pneumoniae (12, 7.1%), Influenza A virus (11, 6.5%), Klebsiella pneumoniae (8, 4.8%) and Haemophilus influenzae (8, 4.8%). The prevalence of S. pneumoniae and M. pneumoniae was highest in patients>60 years (25/87, 28.7%), and<44 years (12/59, 19%), respectively; while K. pneumoniae comprised a larger proportion (4/22, 18%) in the 45-59 years group. CONCLUSIONS: S. pneumoniae was the most common etiology agent in adult patients hospitalized due to CAP in Taiwan and the spectrum of other major pathogens was similar to studies conducted elsewhere in the world. Empiric treatment recommendations developed in other parts of the world may be appropriately adapted for local use after taking into account local resistance profiles. Our data also support the recommendation that urine antigen test be added as an adjunct to adult CAP etiology diagnosis protocol.

High prevalence of phagocytic-resistant capsular serotypes of Klebsiella pneumoniae in liver abscess.

To better understand the role of capsular polysaccharide (CPS) K1 or K2 in Klebsiella pneumoniae liver abscess as well as the development of metastasis to eye, neutrophil phagocytosis of 70 CPS isolates including K1 (n = 23)/K2 (n = 10), non-K1/K2 (n = 37) was evaluated by flow cytometry, fluorescence imaging, and electron microscopy. K1/K2 isolates were significantly more resistant to phagocytosis (P < 0.0001) than non-K1/K2 isolates and displayed increased resistance to intracellular killing. Although mucoid phenotype (M-type) K1/K2 isolates were significantly more resistant to phagocytosis (P = 0.0029) than M-type non-K1/K2, no significant difference in the phagocytosis rate was observed between K1/K2 isolates with M-type and non-M-type (P = 0.0924). Mucoidy is an associated factor that was predominant in K1/K2 isolates, but which itself is not an independent influence on phagocytic resistance. The K1/K2 CPS proved significantly more resistant to phagocytosis than non-K1/K2 CPS in liver abscess isolates (P < 0.0001) and non-abscess isolates (P = 0.0001), suggesting that K1/K2 isolates were generally more virulent in both liver abscess and in non-liver abscess conditions. These findings indicate that resistance of CPS K1 or K2 K. pneumoniae to phagocytosis and intracellular killing presumably contributes to their high prevalence in liver abscess and uniquely in endophthalmitis.

Extended-spectrum cephalosporin compared to cefazolin for treatment of Klebsiella pneumoniae-caused liver abscess.

From January 1995 to May 2000, a total of 107 adults with liver abscess due to Klebsiella pneumoniae admitted at a large medical center in northern Taiwan were reviewed. Patients were considered to have received cefazolin or an extended-spectrum cephalosporin if they received at least 3 days of that antibiotic within the first 5 days of hospitalization. Fifty-nine (55.1%) patients received cefazolin, and 48 (44.9%) patients received an extended-spectrum cephalosporin. The demographic data, clinical features, severities of illness, and rates of early drainage for the two groups were comparable. However, the rates of developing complications for the two groups were significantly different (37.3 versus 6.3%, respectively; P < 0.001). Furthermore, six independent factors preventing severe complications following liver abscess due to K. pneumoniae were identified: normal platelet count, alkaline phosphatase less than 300 U/liter, no gas formation in the abscess, APACHE III score less than 40, use of an extended-spectrum cephalosporin, and early drainage. In conclusion, cefazolin therapy may be suboptimal for patients with liver abscess due to K. pneumoniae despite active in vitro susceptibility. Use of an extended-spectrum cephalosporin and early drainage for patients with liver abscess due to K. pneumoniae are suggested.

Klebsiella pneumoniae liver abscess in Taiwan is not caused by a clonal spread strain.

In Taiwan, the incidence of pyogenic liver abscess caused by Klebsiella pneumoniae has been increasing over the past 2 decades. Although most of the patients have no concurrent biliary tract disease, diabetes mellitus is thought to be an important risk factor for the disease. The incidence of metastatic infections in K. pneumoniae liver abscess, such as endogenous endophthalmitis and other extrahepatic infections, is also higher than that in liver abscess caused by other microbes. Furthermore, the incidence of metastatic infections in K. pneumoniae liver abscess in Taiwan is higher than Western countries. The reasons why K. pneumoniae liver abscess is so common in Taiwan and why diabetes mellitus is a risk factor for the disease are not clear. In this study, blood isolates from 40 patients with K. pneumoniae liver abscess treated at the Taipei Veterans General Hospital from 1995 through 2000 were randomly selected for study. Pulsed-field gel electrophoresis, ribotyping, and serotyping were used for cluster analysis. A total of 15 strains were of serotype K1 and 25 strains were of a serotype other than K1. No major cluster or a closely related strain of K. pneumoniae was found. In conclusion, the results obtained from pulse-field gel electrophoresis and ribotyping of K. pneumoniae isolates do not suggest that liver abscess in Taiwan is primarily caused by a single genetically related strain.