[Recommendations for the diagnosis, therapy and prevention of pneumonia in the immunocompromised host]

High Diagnostic Value of a New Real-Time Pneumocystis PCR from Bronchoalveolar Lavage in a Real-Life Clinical Setting

BACKGROUND

To diagnose Pneumocystis jirovecii pneumonia (PCP), PCR testing in bronchoalveolar lavage (BAL) fluid has recently become an alternative to immunofluorescence testing (IFT); however, its diagnostic accuracy is less clear.

OBJECTIVE

To analyze the diagnostic value of a new semiquantitative real-time PCR (RT-PCR) in BAL in a real-life clinical setting.

METHODS

Retrospective analysis of all RT-PCR results [semiquantitative: negative, weakly positive, and strongly positive; measured in cycle thresholds (Ct)] in BAL in the period between 2010 and 2014. The diagnosis of PCP was defined by clinical, radiological, and laboratory signs and by treatment initiation. Any positive PCR was compared with subsequent IFT.

RESULTS

Of 128 patient samples, 32 had PCP. There is a relevant correlation of high significance between positive PCR Ct and IFT (r = -0.7781, p < 0.001), which amounts to about 60% of the variance. Sensitivity, specificity, and positive predictive values (PPV) of any positive RT-PCR were 100, 80, and 63%, respectively. No patient with negative RT-PCR had PCP. Specificity and PPV are 100% in strongly positive RT-PCR, whereas they decrease to 80 and 21% in weakly positive RT-PCR.

CONCLUSION

A negative RT-PCR (Ct >45) rules out PCP. A strongly positive PCR (Ct <31.5) confirms PCP. In these cases, the diagnostic value of the new method is at least equal to the IFT. A weakly positive PCR probably represents pneumocystis colonization and can occur under PCP treatment.

[Interferon-gamma release assays in tuberculosis diagnostics]

Two years ago, CE certified interferon-gamma release assays (IGRA) were launched on the German market (QuantiFERON-TB Gold In-Tube and T-SPOT-TB). Since this time, a multitude of studies have analysed these assays. Guidelines have been elaborated by national expert committees of England, the USA and Switzerland. However, standards of tuberculosis diagnostics and management may vary from country to country. This statement provides practice relevant recommendations for indications, pre-analytics and the interpretation of IGRA test results under different clinical conditions. The IGRA are integrated into existing guidelines for the management of tuberculosis.

[Pneumonias and immunosuppression]

Pneumonias are common, life threatening complications in immunodeficient patients. A rapid, targeted diagnosis and therapy are decisive for the course of the disease. The etiological spectrum is substantially broader than for immunocompetent patients. Important indications are provided by the type and intensity of the immunosuppression, gaps in the prophylactic concept and particular exposures. For diagnostic planning, high resolution computed tomogram of the thorax is necessary. The standard method for isolating the pathogen is flexible bronchoscopy with bronchoalveolar lavage. Indications for invasive bioptic measures depend on the individual situation, the expected spectrum of pathogens as well as risk factors and adverse effects. Non-invasive antigen and PCR tests complement the diagnostic spectrum, especially for difficult to cultivate pathogens such as fungi and Herpes viruses. The selection of the initial, targeted antimicrobial therapy is based on guidelines. The treatment should be followed after obtaining the relevant microbiological data.

[The radiology of opportunistic pneumonias. I: Epidemiological, laboratory and clinical background]

In the guidelines of the German Society of Pneumology on diagnosis and therapy of opportunistic pneumonias, chest x-ray is listed as the basic diagnostic method in congenital and acquired immunodepression. In case of discrepancy between radiographic and the clinical findings or in cases of bilateral infiltrates, infection refractory to therapy or a difficult course in patients requiring artificial ventilation, a CT, or if necessary, ultrasound or MRI should be carried out. Cross-sectional imaging allows more precise assessment of the radiological pattern, estimation of the degree of severity (number of infiltrated segments) and detection of complications (pleural effusion, empyema, thorax wall infiltration). Clinical and laboratory parameters, bacteriological and serological examinations as well as information on the underlying immunocompromising factors must be taken into account in the differential diagnosis. The radiographic finding is an important diagnostic parameter which is used in the determination of the degree of severity of the pneumonia. The pattern of findings is one of rationales for the use of antibiotic therapy. In the first part of this contribution the epidemiological, laboratory and clinical background of the diagnosis of opportunistic pneumonias is discussed.

Das Kompetenznetzwerk „Ambulant erworbene Pneumonie“ (CAPNETZ)

Community acquired pneumonia (CAP) is a disease with high morbidity and mortality in Germany. However, no reliable data are available about spectrum and resistance of pathogens, course of the disease, evidence based guidelines for treatment, and pathogen-host interactions. The German Ministry of Education and Research recognized these deficits and therefore decided to fund CAPNETZ, a network of competence for community acquired pneumonia. CAPNETZ integrates components of health research as well as clinical and basic research (horizontal network) on one hand and supports cooperation among general practitioners, community hospitals and universities (vertical network). Since October 2002, 1547 patients with CAP have been recruited within the network. First results indicate, that new observations made in terms of symptoms, spectrum of pathogens involved, and treatment modalities will impact on the formulation of new guidelines for the management of community acquired pneumonia.

Ambulant erworbene und nosokomiale Pneumonie

Mortality of pneumonia is low in the outside setting (1%) but rises up to 20% in hospital admitted patients. Early diagnosis and standardized therapy improve patient's prognosis. For community acquired pneumonia age, comorbidity and the setting of therapy (outside department, normal ward or intensive care unit) are the most important variables to choose an adequate antibiotic treatment. For nosocomial pneumonia risk stratification is according to severity of illness, length of hospital stay and antibiotic pretreatment. In the outpatient setting a 7-day monotherapy is mostly successful. In severe illness the combination of a betalactam antibiotic with a new fluorchinolon seems to be superior to an aminoglycosid therapy. Antibiotic resistance due to mistakes in antibiotic therapy is an increasing problem in the intensive care unit. Therefore, pneumonia preventive measures like influenza and pneumococcal vaccination become more important. Standardized hygienical procedures help to reduce nosocomial, mainly ventilator associated pneumonia.