Please select the eligibility criteria that correspond to the clinical trial below.
Title: N/A
Brief Summary: Objective: To evaluate PCT as a marker of bacterial community acquired pneumonia in a Danish Hospital setting. To test if it is possible to reduce the use of antibiotics and the length of stay in hospital, and the willingness of the clinicians to take this new marker under advisement in their choice of treatment.

The study is a randomised, controlled intervention study. All adult patients admitted to the Department of Infectious Disease at Skejby hospital suspected of a lower respiratory tract infection (e.g. CAP, acute exacerbation of COPD and bronchitis) are eligible for inclusion. Patients are randomised to have either PCT guided treatment or standard care, in which case the doctor will not learn the PCT test result. In the PCT group the antibiotic treatment will be based on serum PCT as follows: If PCT is less than 0.25 µg/L antibiotic treatment is discouraged; if PCT is greater than 0.25 µg/L antibiotic treatment is encouraged and if PCT is greater than 0.5 µg/L antibiotic treatment is strongly encouraged. The treating doctor is allowed to overrule the treatment guidelines. The control group will receive antibiotics according to usual practice.

The primary endpoints are antibiotic use and length of stay in hospital. Secondary endpoint is the proportion of patients where the treating doctor chooses to disregard the guidelines.


Options:
A: Inclusion Criteria:

* suspected lower respiratory tract infection
* must be able to give consent

Exclusion Criteria:

* age under 18 years
* not able to give consent
* admitted not primarily because of the respiratory tract infection
* hospital acquired infections
B: Inclusion Criteria:

* written informed consent
* all types of respiratory tract infection according to investigator´s diagnosis

Exclusion Criteria:

* pretreatment with antibiotics in the past 2 weeks
* portal hypertension
* Major surgeries or multiple trauma which require hospitalization, in previous 4 weeks
* Autoimmune disease and systemic diseases (lupus erythematodes, wegener´s disease)
* Peritoneal dialysis
* Acute treated or recently operated medullary c-cell-carcinoma, SCLC, carcinoid
* Other inflammatory diseases (e.g. urinary tract infection, pyelonephritis, pancreatitis
C: Inclusion Criteria:

* Patient hospitalised in the ICU
* Bacterial infection suspected
* At ICU admission the patient do not receive antibiotics or receive antibiotics for less than 24hours and an interval between admission and inclusion \< 12 hours
* During ICU stay, provided that the interval between the start of suspected infection and inclusion is \< 12hours
* Written inform consent from the patient or relatives. The consent may be obtained after the enrollment if the patient is not able to give consent and if there is no relatives

Exclusion Criteria:

* Age \< 18 years
* Pregnancy
* Patient expected to remain hospitalised in the ICU for less than 3 days
* Neutropenia
* Infection or presumed infection requiring prolonged antibiotic therapy (endocarditis,osteo-articular infection, mediastinitis, deep abscess, tuberculosis, pneumocystis pneumonia, toxoplasmosis).
* Simplified Acute Physiology Score II at ICU admission (calculated during the first 12h)
* Attending physician declining to use full life support.
D: Inclusion Criteria:

Fulfilment of all of the following three criteria:

1. Male or female, aged \> 18 years of age.
2. Admitted to the participating Intensive Care Units (ICUs) at the following hospitals: Hvidovre Hospital, Bispebjerg Hospital, Amager Hospital, Herlev Hospital, Glostrup Hospital, and Gentofte Hospital
3. Ability to understand and provide written informed consent to participate in this trial; or ability to understand and provide oral informed consent in the presence of at least one impartial witness who should sign and personally date the consent form; or the subject's legally acceptable representative can understand and provide written informed consent if the subject is not capable of this because of the present mental or physical condition of the subject.

Exclusion Criteria:

A subject will NOT be eligible for inclusion in this trial if any of the following criteria apply:

1. Subjects with known hyperbilirubinaemia (\> 0.4 mg/ml) or hypertriglyceridaemia (\> 10 g/l) since this can interfere with measurements. If subjects with unknown status on these points are included and have PCT measurements, the measuring equipment will detect these conditions.
2. Subjects suffering from a blood disorder, where daily sampling of 7 ml of blood for a maximum of 28 days (210 ml distributed on 28 days) will be an inconvenience or a potential risk, which could compromise the safety of the subject.
3. Subjects who are pregnant or breast feeding

The a priori probability of surviving with the normal recommended diagnostics and treatment with the presently available means to detect infections and, on the other hand, the normal diagnostics and treatment together with daily procalcitonin measurements and prompt clinical reaction should be equal.

Answer: A