Increased risk of incident primary cancer after Staphylococcus aureus bacteremia: A matched cohort study

Susceptibility to infectious disease may be a marker of immunodeficiency caused by unrecognized cancer. To test the hypothesis, the risk of incident primary cancer was estimated among survivors of Staphylococcus aureus bacteremia (SAB) and compared to a random population cohort.Nation-wide population-based matched cohort study. Cases of SAB were identified from a national database and incident primary cancers were ascertained by record linkage. Incidence rate (IR) and ratio (IRR) with 95% confidence interval (CI) of 27 cancers was calculated by Poisson regression.During the first year of follow-up, 165 and 943 incident cases of cancer occurred in the case cohort (n = 12,918 (1.3%)) and the population cohort (n = 117,465 (0.8%)) for an IR of 3.78 (3.22-4.40) and 2.28 (2.14-2.43) per 100,000 person-years. The IRR was 1.65 (1.40-1.95). Of 27 cancers, 7 cancers occurred more frequently amongst cases than controls: cervical cancer (IRR 37.83 (4.23-338.47)), multiple myeloma (IRR 6.31 (2.58-15.44)), leukemia (IRR 4.73 (2.21-10.10)), sarcoma (IRR 4.73 (1.18-18.91)), liver cancer (IRR 3.64 (1.30-10.21)), pancreatic cancer (IRR 2.8 (1.27-6.16)), and urinary tract cancer (IRR 2.58 (1.23-5.39)). Compared to the control population, the risk of cancer was higher for those without comorbidity and with younger age. The overall risk of cancer during 2 to 5 years of follow-up was not increased (IRR 0.99 (95% CI: 0.89-1.11). However, the risk of pharyngeal cancer was increased (IRR 1.88 (1.04-3.39)) and the risk of liver cancer remained increased (IRR 3.93 (2.36-6.55)).The risk of primary incident cancer was 65% higher in the SAB cohort compared to the population cohort during the first year of follow-up and included 7 specific cancers. The risk was higher for those without comorbidity and with younger age. Screening for these specific cancers in selected populations may allow for earlier detection.

Ribavirin inhibition of cell-culture infectious hepatitis C genotype 1-3 viruses is strain-dependent

Ribavirin remains relevant for successful treatment of chronic hepatitis C virus (HCV) infections in low-income settings, as well as for therapy of difficult-to-treat HCV patients. We studied the effect of ribavirin against cell-culture adapted HCV of genotypes 1, 2 and 3, representing ~80% of global infections. TNcc(1a) was the most sensitive to ribavirin, while J6/JFH1(2a) was the most resistant. EC₅₀s ranged from 21 μM (95%CI: 20-22 μM) to 189 μM (95%CI: 173-207 μM). Substitutions at position 415 of NS5B resulted in little or no change to ribavirin sensitivity (0.7-0.9 fold) but conferred moderate drug resistance during extended treatment of genotype 1 (1.8-fold). NS5A and NS5B sequences could alter ribavirin sensitivity 2-4-fold, although their contribution was not simply additive. Finally, we detected limited accumulation of mutations associated with ribavirin treatment. Our findings show that the antiviral effect of ribavirin on HCV is strain-dependent and is influenced by the specific sequence of multiple HCV nonstructural proteins.

Prevalence of anti-hepatitis E virus immunoglobulin G in HIV-infected individuals over three decades

BACKGROUND

Hepatitis E virus (HEV) genotype 3 is endemic in Europe, and the infection is mostly subclinical or acute and self-limiting. However, persistent infection is described among HIV-infected individuals. The prevalence of antibodies against HEV (anti-HEV) among HIV-infected persons varies geographically and is unknown in Denmark. Rates of co-infection with HEV among HIV-infected individuals in Denmark over three decades, from the early 1980s to 2013, were investigated.

METHODS

A total of 2506 HIV-infected persons were investigated from two cohorts followed at Hvidovre Hospital, Denmark. Blood samples were tested retrospectively for anti-HEV, including samples from 2216 persons who were enrolled in a prospective clinical cohort and followed between 1995 and 2013, as well as samples from 290 persons from a historical cohort followed between 1980 and 1994. For anti-HEV seroconverting individuals, serial samples were tested for HEV RNA. Factors associated with anti-HEV status were explored using multivariable logistic regression analysis.

RESULTS

The overall HEV seroprevalence rates were stable during the 1980s, 1990s, and 2000-2013 (23.1%, 22.9%, and 23.7%, respectively). In all decades, rates of anti-HEV increased with older age, and anti-HEV seropositivity was associated with older generations, HIV risk group, and geographic origin. Persistent HEV infection was not detected in any of 57 individuals with anti-HEV seroconversion.

CONCLUSIONS

HEV seroprevalence rates were stable in HIV-infected individuals from the early 1980s to 2013. Rates increased with age. No evidence of persistent HEV infection was detected. Infection with HEV is frequent, but persistent HEV infection is rare among HIV-infected individuals.

Increased risk of diabetes mellitus five years after an episode of Staphylococcus aureus bacteraemia

Background: Diabetes mellitus is a risk factor for infection with Staphylococcus aureus, but it is unclear whether S. aureus infection is a prediabetic condition. Methods: Nationwide population-based matched cohort study. Incidence rate and ratio with 95% confidence interval of diabetes were estimated by negative binomial regression. Results: Of 19,988 individuals with S. aureus bacteraemia and 185,579 population comparators, 667 and 4974 had a primary diagnose of diabetes within five years after discharge of S. aureus bacteraemia corresponding to a more than double risk of diabetes (adjusted incidence rate ratio 2.28 (95% confidence interval: 2.10-2.46)). Other factors associated with an increased risk of diabetes during follow-up were male sex, increasing age and level of comorbidity. Of the S. aureus bacteraemia and population cohort, 422 (2.11%) and 4048 (2.18%), respectively, developed diabetes without complications, while 245 (1.23%) and 926 (0.50%), respectively, developed diabetes with complications. Rates of diabetes without complication were increased for individuals in the S. aureus bacteraemia cohort compared to the population cohort within the first two years after which rates were comparable while rates of diabetes with complications remained higher throughout the five year follow-up period compared to the population cohort. Conclusions: The risk of diabetes was markedly increased up to five years after S. aureus bacteraemia compared to a population cohort. In addition to screening for diabetes during hospital admittance, screening cases of S. aureus bacteraemia for diabetes in the years following S. aureus bacteraemia may allow for earlier detection of diabetes.

Ribavirin-induced mutagenesis across the complete open reading frame of hepatitis C virus genotypes 1a and 3a

Ribavirin (RBV) has been used for the last 20 years to treat patients with chronic hepatitis C virus (HCV) infection. This pluripotent drug is believed to induce mutagenesis in HCV RNA. However, for cell-cultured HCV (HCVcc) this phenomenon has only been investigated in genotype 2a recombinants. Here we studied the mutations that developed in HCVcc of genotypes 1a and 3a treated with RBV or ribavirin triphosphate (RBV-TP) compared to non-treated controls. Analysis was performed on the amplified full-length open reading frame (ORF) of recovered viruses following next-generation sequencing and clonal analyses. Compared to non-treated controls, the spread of TNcc(1a) and DBN3acc(3a) HCVcc was delayed by RBV and RBV-TP at concentrations of 40 µM or higher. The delay in HCVcc spread was associated with increased new single-nucleotide polymorphisms (SNP). Significantly higher numbers of new SNP were observed in TNcc(1a) viruses treated with RBV or RBV-TP compared to matched non-treated controls. RBV or RBV-TP treatment led to significantly increased proportions of new G-to-A and C-to-U SNP compared to non-treated TNcc(1a). Clonal analyses confirmed a significantly increased mutation rate in RBV-treated TNcc(1a). Synonymous pairwise distances increased in both viruses across the complete ORF under RBV and RBV-TP treatment compared to controls. Consensus-shifts in single samples of RBV- or RBV-TP-treated TNcc(1a) viruses occurred in proteins E1, p7, NS3 and NS4B. No non-synonymous consensus changes were observed in DBN3acc(3a). This study supports a biased G-to-A and C-to-U mutagenic effect of RBV and RBV-TP throughout the entire ORF of HCV genotypes 1a and 3a.

Soluble Urokinase Plasminogen Activator Receptor Is a Predictor of Incident Non-AIDS Comorbidity and All-Cause Mortality in Human Immunodeficiency Virus Type 1 Infection

Persistent inflammation and immune activation have been associated with non-AIDS comorbidity and mortality in human immunodeficiency virus (HIV) infection. We aimed to investigate the potential association between soluble urokinase plasminogen activator receptor (suPAR) and incident non-AIDS comorbidity and all-cause mortality in a well-treated HIV-infected population. suPAR was measured by enzyme-linked immunosorbent assay, and events of comorbidity and mortality were ascertained by registry linkage. The study showed an independent association between a high suPAR level at baseline and increased hazard rates for both non-AIDS comorbidities (cardiovascular disease, chronic kidney disease, chronic lung disease, liver disease, and cancer) and all-cause mortality.

Diabetes increases the risk of disease and death due to Staphylococcus aureus bacteremia. A matched case-control and cohort study

BACKGROUND

This study investigated the effect and influence of diabetes severity on susceptibility and 30-day mortality of Staphylococcus aureus bacteremia (SAB).

METHODS

Nationwide population-based study of individuals with SAB and matched population controls. Diabetes severity was categorized based on International Classification of Diseases codes and the odds ratio (OR) with 95% confidence intervals (CI) of SAB associated with diabetes was estimated by conditional logistic regression analysis. Hazard ratios (HR) were analyzed by Cox proportional regression. Analyses were adjusted for age, sex, comorbidity, hospital contact and diabetes duration.

RESULTS

Of 25,855 SAB cases, 2797 (10.8%) had diabetes and 2913 (11.3%) had diabetes with complications compared to 14,189 (5.5%) and 5499 (2.1%) of 258,547 controls. This corresponded to an increased risk of SAB associated with diabetes without complications (OR 1.83 (95% CI 1.74-1.92)) and of diabetes with complications (OR 3.62 (95% CI 3.43-3.81) compared to no diabetes. The risk of SAB was highest within the first year of diabetes. Diabetes without complications was associated with an increased risk of 30-day mortality (HR 1.62 (95% CI 1.01-2.60)) compared to no diabetes. Diabetes with complications was overall not associated with increased 30-d mortality (HR 1.36 (95% CI 0.84-2.20)) except for individuals with ketoacidosis/coma (HR 2.01 (95% 1.17-3.45)).

CONCLUSIONS

Diabetes, particularly, diabetes with complications significantly increased the risk of SAB. In contrast, there was an increased risk of 30-day mortality after SAB for diabetes without complications but not for diabetes with complications overall. Diabetes with ketoacidosis/coma conferred the highest relative risk of 30-day mortality.

Long-term mortality and causes of death associated with Staphylococcus aureus bacteremia. A matched cohort study

OBJECTIVES

Data describing long-term mortality in patients with Staphylococcus aureus bacteremia (SAB) is scarce. This study investigated risk factors, causes of death and temporal trends in long-term mortality associated with SAB.

METHODS

Nationwide population-based matched cohort study. Mortality rates and ratios for 25,855 cases and 258,547 controls were analyzed by Poisson regression. Hazard ratio of death was computed by Cox proportional hazards regression analysis.

RESULTS

The majority of deaths occurred within the first year of SAB (44.6%) and a further 15% occurred within the following 2-5 years. The mortality rate was 14-fold higher in the first year after SAB and 4.5-fold higher overall for cases compared to controls. Increasing age, comorbidity and hospital contact within 90 days of SAB was associated with an increased risk of death. The overall relative risk of death decreased gradually by 38% from 1992-1995 to 2012-2014. Compared to controls, SAB patients were more likely to die from congenital malformation, musculoskeletal/skin disease, digestive system disease, genitourinary disease, infectious disease, endocrine disease, injury and cancer and less likely to die from respiratory disease, nervous system disease, unknown causes, psychiatric disorders, cardiovascular disease and senility. Over time, rates of death decreased or were stable for all disease categories except for musculoskeletal and skin disease where a trend towards an increase was seen.

CONCLUSION

Long-term mortality after SAB was high but decreased over time. SAB cases were more likely to die of eight specific causes of death and less likely to die of five other causes of death compared to controls. Causes of death decreased for most disease categories. Risk factors associated with long-term mortality were similar to those found for short-term mortality. To improve long-term survival after SAB, patients should be screened for comorbidity associated with SAB.

Increased risk of arterial thromboembolic events after Staphylococcus aureus bacteremia: A matched cohort study

OBJECTIVES

An association between infection and arterial thromboembolic events (ATE) has been suggested. Here we examined the risk of myocardial infarction (MI), stroke and other ATE after Staphylococcus aureus bacteremia (SAB).

METHODS

Danish register-based nation-wide observational cohort study between 1995 and 2008 with matched control subjects from the general population.

RESULTS

Within a year, 278 of 15,669 SAB patients and 2570 of 156,690 controls developed MI, stroke or another ATE. The incidence rates among SAB patients were highest within the first 30 days and decreased over a year. The adjusted relative risk of MI, stroke and other ATE during the first 30 days after SAB in patients compared to controls were 2.2 (95% CI: 1.6-3.1), 5.5 (95% CI: 3.8-8.3) and 15.5 (95% CI: 6.9-35), respectively. Compared to controls, the increased adjusted relative risk persisted for 30 days for MI, 180 days for stroke and one year for other ATE. Increasing age, hypertension, atrial flutter/fibrillation, prior ATE and endocarditis in SAB patients were associated with an increased risk of ATE.

CONCLUSIONS

SAB was associated with a short-term increased risk of ATE that persisted longer dependent on type of event. Studies are warranted to investigate treatment strategies to diminish ATE after SAB.

Increased risk of venous thromboembolism within the first year after Staphylococcus aureus bacteraemia: a nationwide observational matched cohort study

OBJECTIVES

Recent evidence suggests that there is an association between infection and venous thromboembolism (VTE). Here, we examined the risk of VTE after Staphylococcus aureus bacteraemia (SAB) compared to the risk in control subjects.

DESIGN AND SETTING

Register-based nationwide observational cohort study of hospitalized patients and matched control subjects from the general population in Denmark between 1995 and 2008.

RESULTS

Amongst 15 669 SAB cases and 156 690 controls, 182 and 511, respectively, experienced VTE within 1 year. The overall incidence rate (IR) of VTE amongst cases was highest within the first 30 days [IR of deep vein thrombosis (DVT), 39.3 (95% confidence interval (CI) 28.9-53.4)/1000 person-years (PYs); IR of pulmonary embolism (PE), 16.3 (95% CI 10.1-26.2)/1000 PYs]. IRs of DVT were particularly increased amongst cases with a previous diagnosis of VTE, community-acquired infection, a history of injection drug use and in younger age groups. The overall hazard ratio of VTE for cases compared to controls declined from 15.6 (95% CI 10.3-23.5) in the first 30 days after SAB to 4.5 (95% CI 3.2-6.2) from 181 to 365 days after infection. The increased risk of VTE amongst SAB patients persisted after excluding cases with identified VTE risk factors.

CONCLUSIONS

There was a particularly high risk of VTE during the first month following an episode of SAB. The risk declined over time, but remained at a threefold increased level compared to control subjects, suggesting that there are shared risk factors for SAB and VTE. Patients with SAB and well-documented risk factors for VTE may benefit from thromboprophylaxis.

A nationwide study of comorbidity and risk of reinfection after Staphylococcus aureus bacteraemia

BACKGROUND

Data on risk factors and rates of reinfection associated with Staphylococcus aureus bacteraemia (SAB) are sparse.

METHODS

We conducted a nationwide cohort study of cases of SAB diagnosed between 1995 and 2008. Reinfection was defined as an episode of SAB more than 90 days after the initial episode of SAB. Comorbidity was evaluated by the Charlson Comorbidity Index (CCI). Cox proportional hazards modelling was used to estimate hazard rates (HR).

RESULTS

Of 10,891 eligible patients, 774 (7.1%) experienced reinfection a median of 458 days (range 90-5021 days) after their primary SAB episode corresponding to a reinfection rate of 1459 (95% confidence interval (CI): 1357-1562) per 100,000 personyears. In multivariate analysis, sex, origin, a vascular or peritoneal device, endocarditis and comorbidity were associated with reinfection. The association was more than two-fold higher among patients in dialysis and for patients with severe comorbidity (CCI ≥ 2). HIV infection (Hazard ratio (HR) 6.18, 95% CI: 4.17-9.16), renal disease (HR 3.92, 95% CI: 3.22-4.78), diabetes with complications (HR 2.11, 95% CI: 1.69-2.62), diabetes without complications (HR 1.61, 95% CI: 1.34-1.93), mild (HR: 1.94, 95% CI: 1.36-2.76) and severe liver disease (HR 2.08, 95% CI: 1.08-4.03), peptic ulcer (HR 1.33, 95% CI: 1.03-1.72), and paraplegia (HR 2.15, 95% CI: 1.02-4.54) were each associated with an increased risk of reinfection.

CONCLUSIONS

Patients with previous SAB have a 60-fold higher risk of SAB compared to the general population. Patients with HIV infection, renal disease, diabetes, liver disease, peptic ulcer and paraplegia had the highest rates of reinfection.

Stable incidence and continued improvement in short term mortality of Staphylococcus aureus bacteraemia between 1995 and 2008

Background

The objective of this study was to assess temporal changes in incidence and short term mortality of Staphylococcus aureus bacteraemia (SAB) from 1995 through 2008.

Methods

The study was conducted as a nation-wide observational cohort study with matched population controls. The setting was hospitalized patients in Denmark 1995-2008. Uni- and multivariate analyses were used to analyze the hazard of death within 30 days from SAB.

Results

A total of 16 330 cases of SAB were identified: 57% were hospital-associated (HA), 31% were community-acquired (CA) and 13% were of undetermined acquisition. The overall adjusted incidence rate remained stable at 23 per 100 000 population but the proportion of SAB cases older than 75 years increased significantly. Comorbidity in the cohort as measured by Charlson comorbidity index (CCI) score and alcohol-related diagnoses increased over the study period. In contrast, among the population controls the CCI remained stable and alcohol-related diagnoses increased slightly. For HA SAB crude 30-day mortality decreased from 27.8% to 21.8% (22% reduction) whereas the change for CA SAB was small (26.5% to 25.8%). By multivariate Cox regression, age, female sex, time period, CCI score and alcohol-related diagnoses were associated with increased mortality regardless of mode of acquisition.

Conclusions

Throughout a 14-year period the overall incidence of SAB remained stable while the overall short term prognosis continued to improve despite increased age and accumulation of comorbidity in the cohort. However, age and comorbidity were strong prognostic indicators for short term mortality.