KlebsiellaLiver Abscess: A Coast‐to‐Coast Phenomenon

SIR—We were delighted to read the article by Rahimian et al. [1], in which the authors reported that Klebsiella pneumoniae was the organism that was most commonly associated with pyogenic liver abscess (PLA) at their New York City institutions (Bellevue Hospital and New York University Downtown Hospital). In February 2005, we described a 5-year study from our institution, Naval Medical Center San Diego, which revealed the same high frequency of K. pneumoniae liver abscesses and showed that several of cases occurred in patients with atypical characteristics (i.e., nondiabetics and non-Asians) [2]. In addition, Rahimian and colleagues noted a markedly decreased mortality rate among patients with K. pneumoniae liver abscess (2.5%). Although we did not focus on this particular point, the mortality rate in our series was atypically low as well (0%). These 2 studies indicate a trend in the United States toward a predominance of K. pneumoniae as the bacterial agent responsible for PLA. This subtype of PLA is noteworthy, because it leads to a high frequency of bacteremia (which was observed in both studies), as well as to metastatic complications in up to 10% of patients. This latter feature is well described in the Asian literature [3] but is strikingly absent from both of these US-based studies. Several questions remain unanswered, including what the extent of this trend is throughout the United States and other western countries and whether PLA is becoming associated with decreasing morbidity and mortality rates because of a change in the microbiological characteristics of Klebsiella species or because of improved therapeutic interventions. In addition, we would be interested to know whether more of the patients in the authors' series presented to the hospital with this condition during the later stages of the 10-year study period, which would indicate a gradual, recent shift in frequency rather than an unrecognized chronic phenomenon. In our review of all US cases of Klebsiella PLA, we found that 7 (58%) of 12 cases were reported after 1998, indicating that the former pattern is more likely. Potential conflicts of interest. All authors: no conflicts.