Please select the eligibility criteria that correspond to the clinical trial below.
Title: Impact of Procalcitonin to Reduce Antibiotics Use in ICU Adults Patients
Brief Summary: The study is a prospective, randomized, controlled intervention trial conducted in 9 centers, comparing a conventional strategy versus a PCT-guided strategy to start or to discontinue antibiotics, in patients with suspected community or hospital- acquired infection.


Options:
A: Inclusion Criteria:

* Severe sepsis or septic shock according to ACCP/SCCM criteria
* Onset of severe sepsis or septic shock \<24 h
* Age \>= 18 years
* Informed consent

Exclusion Criteria:

* Pregnant or breast-feeding women
* Fertile female women without effective contraception
* Participation in interventional clinical trial within the last 30 days
* Current participation in any study
* Former participation in this trial
* Selenium intoxication
* No commitment to full patient support (i.e. DNR order)
* Patient's death is considered imminent due to coexisting disease
* Relationship of the patient to study team member (i.e. colleague, relative)
* Infection where guidelines recommend a longer duration of antimicrobial therapy (i.e. endocarditis, tuberculosis, malaria etc)
* Immunocompromised patients
B: Inclusion Criteria:

1. Patients 18 years of age or older, admitted from the community or a nursing home with acute (i.e., at least 1 day but less than 28 days) LRTI as the main diagnosis consisting of having at least two of the following:

   * new or increased respiratory signs or symptoms (i.e., cough, sputum production, dyspnea, auscultatory findings of abnormal breath sounds and rales, pleuritic chest pain) with or without inflammatory signs (core body temperature \> 38.0° C, leukocyte count \> 10 or \< 4 x 10\^9 cells L-1).
   * CAP is defined by the presence of LRTI along with a new or increased infiltrate on chest radiograph. Severity scores of CAP (pneumonia severity index \[PSI\] and CURB-65) will be calculated.
   * COPD is defined by post-bronchodilator spirometric criteria according to the GOLD-guidelines as a FEV1/FVC ratio below 70% and the severity categorized into mild (FEV1 \<= 80% of predicted), moderate (50% \>= FEV1 \< 80%), severe (30% \>= FEV1 \< 50%) and very severe (FEV1 \< 30%), respectively. Severity of acute exacerbations of COPD will be graded as proposed. Acute bronchitis is defined as LRTI in the absence of an underlying lung disease or focal chest signs and infiltrates on chest X-ray, respectively. Patients who are on admission judged as having an LRTI but have another final diagnosis, will be classified as "others".
2. Ability to understand verbal and written instructions and informed consent.

Exclusion Criteria:

1. Patients unable to give written informed consent, e.g. with severe dementia or patients not understanding German (or other local language) and no translation (e.g. family members) available.
2. Patients with active intravenous drug use.
3. Severe immunosuppression (e.g. patients infected with human immunodeficiency virus infection and a CD4 count below 350 x 10\^9/L, patients on immunosuppressive therapy after solid organ transplantation and neutropenic patients with present neutrophil count \< 500 x 10\^9/L and patients under chemotherapy with neutrophils 500-1000 x 10\^9/L with an expected decrease to values \< 500 x 10\^9/L); patients with cystic fibrosis, infection with M. tuberculosis, L. pneumophila, Listeria spp. hospital stay within 14 days of inclusion.
4. Accompanying chronic (e.g. osteomyelitis), abscess (e.g. brain, pleural empyema) infection or endocarditis.
5. Terminal and very severe medical co-morbidity where death is imminent or has to be expected in the current hospitalization (e.g. due to malignancy, cardiac, renal or hepatic failure, comfort therapy).
C: Inclusion Criteria:

* 18 years or older
* Informed consent
* Respiratory tract infection based on the clinical judgement of the primary care physician

Exclusion Criteria:

* Antibiotic pretreatment in previous 14 days
* 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
D: 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.

Answer: D