Pyogenic liver abscess in the elderly: What we have learned?

Pyogenic liver abscess (PLA) remains a health problem in Taiwan. The annual incidence of PLA in Taiwan was 17.5 per 100,000 individuals in 2004, in contrast to only 2.3 and 3.6 per 100,000 individuals in Canada and the United States in 2003 and 2005, respectively. In Taiwan, Klebsiella pneumoniae is the leading pathogen, presenting in 78e80% of culture-confirmed cases, which is different from Western countries, where the most frequent etiological agents of PLA are Streptococcus, Escherichia coli, Staphylococcus, and anaerobic bacteria. The initial clinical symptoms and signs of PLA were not significantly different in both K. pneumoniae and non-K. pneumoniae patients. However, the K. pneumoniae patients were more likely to be younger and frequently associated with diabetes mellitus (DM) and had a high incidence of septic endophthalmitis (mostly due to serotypes K1 and K2 K. pneumoniae) and other metastatic infections, but with a lower mortality. The non-K. pneumoniae patients were more likely to be older and frequently associated with malignancy and had a higher mortality. In the latest issue of the Journal, Kang and Hwang analyzed 2319 cases of PLA from the National Health Insurance database of Taiwan in 2007 and reported that older patients (age 65 years) had a higher rate of gastroenterological cancers compared to younger patients (age <65 years). Our recent investigation further explored the association between hepatocellular carcinoma and PLA. The impact of advanced age on PLAwas also addressed in this study. We found that around 2% (698/32,454) of PLA patients in Taiwan presented with the disease as the initial manifestation of underlying hepatocellular carcinoma. Age 65 years was one of the independent risk factors. Physicians should not ignore the possibility of underlying hepatocellular carcinoma in PLA patients with advanced age. In older patients with PLA, a variety of microorganisms could be identified. In addition to K. pneumoniae, other causative agents such as E. coli and polymicrobial with or without anaerobic bacteria were also more frequently found in older patients. Previous studies revealed that a high ratio of hepatobiliary malignancy was found in non-K. pneumoniae patients. Physicians should pay attention to the associated malignancy in geriatric PLA patients, which can lead to a poor prognosis. Kang and Hwang reported that older patients had longer hospital stays and higher in-hospital mortality rate. Indeed,