ARCHIVED - Infectious Diseases News Brief - January 18, 2013

COPD Patients at Risk of Dangerous Bacterial Infections

It is well known that COPD patients run a higher risk of contracting respiratory infections. However, a new thesis from Lund University in Sweden shows that they are also at higher risk of other bacterial infections, such as tuberculosis (TB) and pneumococcal and staphylococcal infections that can cause serious illness.

The abbreviation COPD stands for chronic obstructive pulmonary disease and the disease makes it difficult for patients to breathe. However, the disease affects other organs as well as the lungs. It is also linked to an increased risk of conditions such as diabetes, cancer and heart failure.

"Despite this, until now most focus has been on respiratory infections; infections in other organs have not been studied to the same extent," says Dr Malin Inghammar. In her thesis, Dr Inghammar has shown that individuals in Sweden who have been diagnosed with COPD have a three times higher risk of active tuberculosis than the population in general. They are also at higher risk of invasive pneumococcal disease, a type of infection that can cause meningitis and septicaemia.

In another study, Malin Inghammar has looked at the presence of bacteria in the blood of COPD patients and control subjects from the general population. A wide range of bacteria, such as coliform bacteria and staphylococcus aureus, were seen to be 2.5 times more frequent in the blood of patients with COPD.

Tuberculosis is a rare disease in Sweden, so the association between COPD and TB is not of great importance in Sweden. However, the association could be important for countries such as India and China, where TB is still a common disease and where smoking is on the increase. Doctors may need to have increased awareness of dangerous infection-causing bacteria in any country.

"The next step is to study what causes the link. Does the cortisone treatment that is usually given to COPD patients make them vulnerable to infections? Or is the susceptibility to infection due to other factors, such as the weight loss, muscle weakness and anemia that are associated with the condition?" asks Malin Inghammar.

Her findings could in the future lead to changes in the treatment of COPD. If COPD patients are at extra high risk of hospital-acquired infections, then perhaps more care should be taken before admitting them to hospital, and greater reflection made on all the factors that could entail an increased risk of infection.

Source: COPD Patients at Risk of Dangerous Bacterial Infections

Screening for Hepatitis C Virus Infection in Adults: A Systematic Review for the U.S. Preventive Services Task Force

Background
Identification of hepatitis C virus (HCV)–infected persons through screening could lead to interventions that improve clinical outcomes.

Purpose
To review evidence about potential benefits and harms of HCV screening in asymptomatic adults without known liver enzyme abnormalities.

Data Sources
English-language publications identified from MEDLINE (1947 to May 2012), the Cochrane Library Database, clinical trial registries, and reference lists.

Study Selection
Randomized trials and cohort, case–control, and cross-sectional studies that assessed yield or clinical outcomes of screening; studies reporting harms from HCV screening; and large series reporting harms of diagnostic liver biopsies.

Data Extraction and Data Synthesis
Multiple investigators abstracted and checked study details and quality by using predefined criteria. No study evaluated clinical outcomes associated with screening compared with no screening or of different risk- or prevalence-based strategies. Three cross-sectional studies in higher prevalence populations found that screening strategies that targeted multiple risk factors were associated with sensitivities greater than 90% and numbers needed to screen to identify 1 case of HCV infection of less than 20. Data on direct harms of screening were sparse. A large study of percutaneous liver biopsies (n = 2740) in HCV-infected patients with compensated cirrhosis reported no deaths and a 1.1% rate of serious adverse events (primarily bleeding and severe pain).

Limitations
Modeling studies were not examined. High or unreported proportions of potentially eligible patients in the observational studies were not included in calculations of screening yield because of unknown HCV status.

Conclusion
Although screening tests can accurately identify adults with chronic HCV infection, targeted screening strategies based on the presence of risk factors misses some patients with HCV infection. Well-designed prospective studies are needed to better understand the effects of different HCV screening strategies on diagnostic yield and clinical outcomes.

Source: Screening for Hepatitis C Virus Infection in Adults