Nineteen patients (12.8%) died of bacteraemia. The case fatality rate differed in bacteraemias caused by different organisms: S. aureus 8/41 (19.5%), Str. pneumoniae 8/42 (19.0%), β-hml str.2/23 (8.7%), and E. coli 1/43 (2.3%). Bacteraemia was community-acquired in 119 patients (79.9%) and nosocomial in 30 (20.1%).
Predisposing factors and underlying diseases of bacteraemia are given in Table . Four differed bacteraemias differed statistically significantly from each other in the number of smoking patients (current smokers or ex-smokers, p = 0.007). Smoking was common in pneumococcal bacteraemic patients (65.0% of patients current smokers or ex-smokers) whereas 27.5% of E. coli bacteraemic patients were current smokers or ex-smokers. S. aureus bacteraemia was the most common pathogen in patients with rheumatoid arthritis. Bacteramias differed statistically significantly from each other in the number of male patients (p = 0.003). Only 30.2% of E. coli bacteramia patients were male whereas 68.3% of S. aureus bacteraemic patients were male. S. aureus was a common pathogen in nosocomial infection; 39% of S. aureus bacteraemias were nosocomial infections.
Predisposing factors and underlying diseases of bacteraemia
The sources of the infection were identifiable in 132 patients and are listed in Table . Clinical data on all patients and on patients with bacteraemia caused by different organisms are shown in Table . The case fatality rate in relation to predisposing factors and underlying diseases is given in Table . Obesity, smoking, alcohol abuse, COPD and rheumatoid arthritis proved significant risk factors for case fatality in univariate analysis (table ).
Clinical data on 149 patients with 4 different bacteraemias
Case fatality in relation to predisposing factors and underlying diseases (univariate analysis)
Myocardial infarction occurred in 11 (7.4%) patients and cerebral infarction in 7 (4.7%) during the month following positive blood culture. Twenty-six per cent of patients older than 60 years were treated in ICU compared to 38 per cent of those aged 60 or younger (p = 0.104).
Day 30 case fatality was higher in obese bacteraemic patients than in nonobese patients (25.9% vs. 3.4%, p = 0.002, RR 9.8; 95% CI 2.3–41.3). The median BMI was significantly higher among those who died compared to survivors (33 vs. 26, p = 0.003). Obese and nonobese study groups did not differ statistically significantly from each other in numbers needing ICU treatment (25.9% vs. 28.7%, p = 0.78, RR 0.9; 95% CI 0.3–2.3). Obese patients needed mechanical ventilation more often than nonobese, but the difference was not statistically significant (18.5% vs 8.0%, p = 0.152, RR 2.6; 95% CI 0.8–9.0). However, more obese than nonobese patients died in ICU treatment (5/7 vs. 3/25; p = 0.005, RR 18.3; 95% CI 2.4–140.4). The obese had high SOFA scores (value >4 on day 1–3 after positive blood culture finding) more often than nonobese, but the difference was not statistically significant (44.0% vs 23.8%, p = 0.05, RR 2.5; 95% CI 1.0–6.5). The obese and nonobese groups did not differ statistically significantly in the occurrence of hypotension (37.0% vs 31.0%, p = 0.561, RR 1.3; 95% CI 0.5–3.2), or in the number of patients with neurological deficit (lowered GCS) (44.4% vs 33.3%, p = 0.293, RR 1.6; 95% CI 0.7–3.9)
Forty-four per cent of obese bacteraemic patients had previously been diagnosed with type 2 diabetes as against 12.6% of nonobese patients (p < 0.001). Patients with type 2 diabetes died more often than those without type 2 diabetes, but the difference was not statistically significant (Table ).
The day 30 case fatality rate in bacteraemic patients was higher in current or ex-smokers than in nonsmokers (19.7% vs. 1.4%, p < 0.001, RR 16.9; 95% CI 2.1–133.5); ninety-three per cent of patients who died were current or ex-smokers (Table ). Current or ex-smokers needed ICU treatment (39.4% vs 18.6%, p = 0.007, RR 2.9; 95% CI 1.3–6.2) and mechanical ventilation (21.2% vs 5.7%, p = 0.008, RR 4.4; 95% CI 1.4–14.3) more often than nonsmokers during the bacteremia episode. Current or ex-smokers died more often in ICU treatment compared to nonsmokers (10/26 vs 1/13, p = 0.044, RR 7.5; 95% CI 0.8–66.9) and had high SOFA scores (value > 4 on day 1–3 after positive blood culture finding) more often than nonsmokers (33.3% vs 16.4%, p = 0.029, RR 2.6; 95% CI 1.1–6.0). The current or ex-smoker patient groups did not differ statistically significantly from the nonsmoker group in the occurrence of hypotension (42.4% vs 28.6%, p = 0.091, RR 1.8; 95% CI 0.9–3.8) or in numbers with neurological deficit (lowered GCS) (43.9% vs 32.9%, p = 0.184, RR 1.6; 95% CI 0.8–3.2).
Thirty-eight patients (35.2%) were current smokers while 70 (64.8%) had never smoked. When current smokers were compared to nonsmokers (ex-smokers excluded from this analysis) the adverse effect of smoking for prognosis of bacteraemia was emphasized. The day 30 case fatality rate in bacteraemic patients were higher in current smokers than in nonsmokers (21.1% vs. 1.4%, p < 0.001, RR 18.4; 95% CI 2.2–153.7). Current smokers needed ICU treatment (50.0% vs 18.6%, p = 0.001, RR 4.4; 95% CI 1.8–10.5) and mechanical ventilation (31.6% vs 5.7%, p < 0.001, RR 7.6; 95% CI 2.3–25.8) more often than nonsmokers during the bacteremia episode. This adverse effect remained even after smoking cessation; 5/28 (17.9%) patients died in the ex-smoker group compared to 1/70 (1.4%) of those who had never smoked (p = 0.007, RR 15.0; 95% CI 1.7–135.1). Fifty-nine per cent of males were current or ex-smokers as against 36.9% of females (p = 0.01).
The day 30 case fatality rate in bacteraemic patients was higher in alcohol abusers compared to those not given to alcohol abuse (29.2% vs 9.6%, p = 0.008, RR 3.9; 95% CI 1.3–11.2). Alcohol abusers needed ICU treatment (66.7% vs 24.8%, p < 0.001, RR 6.1; 95% CI 2.4–15.5) and mechanical ventilation (41.7% vs 9.6%, p < 0.001, RR 6.7;95% CI 2.5–18.4) more often than those not abusing. Alcohol abusers died more often in ICU treatment, the difference being, however, not statistically significant (7/16 vs 8/31, p = 0.211, RR 2.2, 95% CI 0.6–8.0). Alcohol abusers had high SOFA scores (value >4 on day 1–3 after positive blood culture finding) more often than those without alcohol abuse (65.2% vs 21.4%, p < 0.001, RR 6.9; 95% CI 2.6–18.1). The occurrence of hypotension was more common among abusers than in their counterparts (70.8% vs 31.2%, p < 0.001, RR 5.4; 95% CI 2.1–14.0) and were more likely to develop neurological deficit (lowered GSC) (75.0% vs 33.6%, p < 0.001, RR 5.9; 95% CI 2.2–16.0). Eighteen out of 21 (85.7%) alcohol abusers were current smokers or ex-smokers and 4 out of 24 (16.7%) had liver cirrhosis.
The effect of obesity, smoking and alcohol abuse on day 30 case fatality were studied together with age, sex and organism in a multivariate model. Obesity remained a significant risk factor associated with case fatality also in this adjusted model (p = 0.03, RR 6.4; 95% CI 1.2–34.4), together with smoking (P = 0.02, RR 23.0; 95% CI 1.7–321.6).