We investigated the epidemiology of different serotypes of Klebsiella pneumoniae isolates causing bacteremic liver abscess (LA) using multilocus sequence typing (MLST). MLST and molecular typing were performed for 41 K1 (19 LA), 37 K2 (5 LA), and 33 non-K1/K2 (6 LA) isolates that were derived from a previous one-year K. pneumoniae bacteremia cohort. Capsular serotypes and rmpA of these isolates were determined by polymerase chain reaction (PCR) methods. Among the 41 K1 isolates, 39 were ST23 and the remaining two isolates were ST23 single-locus variant. There were 11 STs among K2 isolates. ST65 was the most common (n = 10), followed by ST86, ST373, and ST375. Only ST65 (n = 3), ST373 (n = 1), and ST375 (n = 1) caused LA, and ST65 was a three-locus variant of ST23. For non-K1/K2 isolates, the ST types varied widely. ST218 (K57) was the most common type (n = 6, 18 %), and it was a single-locus variant of ST23 and caused two cases of LA. The existences of rmpA among serotypes varied (100 % for K1, 89 % for K2, and 55 % for non-K1/K2). For isolates causing LA, all of them were positive for rmpA. For non-K1/K2 isolates causing infections other than LA, the positivity of rmpA ranged from 0 % (biliary tree infection) to 67 % (pneumonia). In this one-year cohort, all K1 isolates were ST23 or its single-locus variants, but the composition of ST types among K2 isolates was quite variable. ST23 and its one- (ST1005 and ST218) and three-locus (ST65) variants comprised 80 % of isolates causing LA.

Time to positivity (TTP) of blood cultures in patients with bacteraemia is considered to be a predictor of outcome for some bacterial species. Two hundred and thirty-one patients with Klebsiella pneumoniae monomicrobial bacteraemia at a hospital from 1 January to 31 December 2007 were prospectively enrolled. TTP <7 h (46 patients, 19.9%) was associated with a higher Pittsburg bacteraemia score (6.2 +/- 5.5 vs. 3.7 +/- 4.3, p 0.002), fewer non-fatal diseases by the McCabe classification (39.1% vs. 64.9%, p 0.002), a higher percentage of patients with liver cirrhosis, active malignancy, and chemotherapy within 3 months (28.3% vs. 11.9%, p 0.007; 28.3% vs. 14.6%, p 0.031; 23.9% vs. 5.4%, p <0.001), more primary bacteraemia (45.7% vs. 22.2%, p 0.002), and a higher 30-day mortality rate (47.8% vs. 21.1%, p <0.001). Risk factors for 30-day mortality in the univariate analysis included higher Pittsburg bacteraemia score (5.8 +/- 5.3 vs. 3.7 +/- 4.3, p 0.002), primary bacteraemia (41.0% vs. 21.8%, p 0.004), TTP <7 h (36.1% vs. 14.1%, p <0.001), and the presence of active malignancy (29.5% vs. 12.9%, p 0.004). In the multivariate analysis, higher Pittsburg bacteraemia score (OR 1.07; 95% CI 1.01-1.14), TTP <7 h (OR 2.46; 95% CI 1.20-5.05) and active malignancy (OR 2.21; 95% CI 1.03-4.73) were the significant factors associated with 30-day mortality. In the Kaplan-Meier survival curve, short TTP was significantly associated with mortality at all time-points after admission. TTP of blood cultures, interpreted with a cut-off point of <7 h, in patients with K. pneumoniae bacteraemia can provide useful prognostic information.

A short time to positivity (TTP) correlates with poor clinical outcome in patients with Staphylococcus aureus bacteraemia, but the association between sequential TTPs and the outcome of these patients is unclear. Sequential TTPs from patients with S. aureus bacteraemia persisting for >48 h were analysed with respect to clinical parameters and patient outcome at a tertiary hospital. During the 5-year study period, 87 patients (9.2%; mean age of 64 years) had persistent S. aureus bacteraemia, with an average Pittsburgh bacteraemia score of 2.7. Forty-eight patients (55%) had methicillin-resistant S. aureus infection, and 28 (32%) had nosocomial infection. The most common underlying disease was end-stage renal disease (43%). The most common type of infection was catheter-related infection (31%), followed by infective endocarditis (18%). The in-hospital mortality rate was 40%. Higher Pittsburgh scores (p 0.005; OR 1.37; 95% CI 1.1-1.7) and a second TTP/first TTP ratio of <1.5 (p 0.004; OR 0.2; 95% CI 0.07-0.6) were independent risk factors for mortality. Among patients receiving adequate empirical therapy, a second positive blood culture growing within 12 h was more frequent in patients who finally died. Factors associated with a second TTP/first TTP ratio of <1.5 included older age (p 0.02; OR 0.96; 95% CI 0.92-0.99) and inadequate empirical antimicrobial therapy (p 0.01; OR 3.53; 95% CI 1.42-8.78). Among patients with persistent S. aureus bacteraemia, a second TTP/first TTP ratio of <1.5 is a predictor of poor outcome. Physicians should search for interventions guaranteeing that all patients with S. aureus bacteraemia receive adequate empirical therapy.

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