Characteristics of bloodstream and complicated skin infections in patients with alcoholism

Introduction: Alcohol has been consumed for thousands of years as a part of tradition, celebration and even medicinally. Despite the cultural role of alcoholic beverages historically and today, addiction and excessive alcohol consumption are increasingly associated with social and physical harms, including infectious diseases. Alcoholism is a recognized risk factor for pneumonia. Additionally, alcoholism has been associated with bloodstream infection risk and severity. Many authors speculate that the detrimental effects of chronic alcohol use on the immune system are a part of the reason alcohol is associated with infectious diseases. Poor socioeconomic standing and impaired care seeking in persons with alcoholism may contribute to increased risk and severity of infections. This thesis aimed to study the characteristics of three infections in patients with alcoholism, a subject not previously investigated. We compared patient and disease characteristics, treatment and outcomes, of patients with alcoholism to patients without alcoholism, in Staphylococcus aureus bacteremia (SAB), complicated skin and skin structure infections (cSSSIs), and candidemia. Study population: This thesis had three different study populations. The data in each study population was stratified according to the presence or absence of comorbid alcoholism to compare the characteristics of each infection in patients with alcoholism to patients without alcoholism. Study I. A multicenter pro- and retrospective study in Finland including all adult patients with SAB from January to May 1999, January 2000 to August 2002, and all adult patients with SAB from one study site in January 2006 to December 2007. A total of 617 cases of SAB were included, of which 13% (N = 83) had comorbid alcoholism. Study II. All hospitalized adult patients with ICD-10 codes for skin and skin structure infection (SSSI) treated in two cities, Helsinki, Finland and Gothenburg, Sweden from 2008 to 2011 were retrospectively identified. After applying criteria for cSSSI the study population had a total of 460 patients, of which 9% (N = 40) had comorbid alcoholism. Study III. All adult patients hospitalized in the Helsinki and Uusimaa hospital district with a blood culture positive for Candida species from January 2007 to December 2016 were retrospectively identified. A total of 329 patients were included and comorbid alcoholism was present in 21% (N = 69). Main results: Study I. Patients with alcoholism, compared to patients without alcoholism, had more cases of severe sepsis (25% vs. 7%, P < 0.001), intensive care unit (ICU) admission (39% vs. 17%, P < 0.001) and higher Pitt bacteremia scores. Mortality in patients with alcoholism was twofold compared to non-alcoholics at 14 days (14% vs. 7%, P = 0.018) and thereafter throughout the 90 days of follow-up. Patients with alcoholism were slightly younger. No differences were observed in McCabe´s classification of underlying conditions. Deep infection foci were identified in three-fourths of both patients with and without alcoholism. Infectious disease specialist (IDS) consultation and diagnostic procedures were provided equally. Study II. Patients with alcoholism had comparatively longer length of hospital stay, more ICU admission, more surgical interventions, bacteremia, interdepartmental transfers and clinical failure. Mortality at 30 days was low and no differences were observed (4% vs. 5%, NS). Patients with alcoholism were somewhat younger, and with the exception for liver diseases and post-traumatic wound, had equal rates of comorbidities and predisposing factors to skin infection compared to non-alcoholics. No differences were observed in infection type. Streptococcal etiology was more common in patients with alcoholism. Study III. One fifth of patients with candidemia had alcoholism. No differences were found in 30-day mortality (29% vs. 31%), ICU admission, metastatic foci or Candida species distribution. Typical candidemia risk factors were equally or less common in patients with alcoholism compared to non-alcoholics, including malignancy (20% vs. 34%, P = 0.026), central venous catheter (48% vs. 50%, NS), and gastrointestinal surgery (20% vs. 24%, NS). Candidemia onset during ICU treatment was more common in patients with alcoholism than in patients without alcoholism (19% vs. 10%, P = 0.033). Patients with alcoholism were on average five years younger than patients without alcoholism and had fewer serious or life-threatening comorbidities. Patients with alcoholism had prompt central venous catheter (CVC) removal compared to non-alcoholics (61% vs. 37%, P = 0.017), as well as high rates of non-delayed appropriate antifungal therapy. Conclusions: Patients with alcoholism had higher SAB mortality and increased disease severity compared to non-alcoholics. The disease severity and resource utilization in the treatment of cSSSI was higher in patients with alcoholism. Alcoholism affects a significant proportion of patients with candidemia, and patients with alcoholism do not have typical candidemia risk factors or worse outcomes than non-alcoholics with candidemia.