The objective of this single-center prospective observational study is to evaluate possible independent risk factors for multidrug-resistant (MDR) bacteria upon ICU admission by analyzing comorbidities, epidemiological data, and laboratory/microbiological information of the subjects.

Background: Infection is one of the main reason for a patient to be admitted to an intensive care unit (ICU) and it's fundamental to use the right antibiotic as soon as possible, possibly needing broad-spectrum antibiotics. However, the main problem is that widening the spectrum of drugs will generate pressure on the hospital microbiota, leading to the development of multi-drug resistant bacteria

Purpose: A large number of ICU-admitted patients have infection/sepsis as their major problem, requiring treatment with antibiotics. With knowledge of the presumed risk factors for antibiotic resistance, the assistant physician could use broad-spectrum drugs with greater certainty.

Objectives: Our objective will be to evaluate risk factors for infection caused by multi-drug resistant germs upon ICU admission and assess the severity of the disease in comparison to patients infected with susceptible bacteria. Ultimately, we aim to develop and validate a clinical tool to assist physicians in selecting the appropriate antibiotic for their patients

Methods: An observational prospective study with a control group will be conducted, including all patients admitted to the ICU with an infectious disease initiated within 48 hours of hospital admission and with a positive microbiologic result. Patients with isolation of only susceptible bacteria will be allocated to the control group, while patients with MDR bacteria will be assigned to the study group, referred to as the MDR group. The data to be collected will include sex, age, previous use of antibiotics in the last three months, previous hospital admissions, previous isolation of MDR germs, sensitivity profile of the isolated germs, severity of disease (measured by SAPS 3), presence of sepsis diagnosis at admission, length of stay in the ICU, and 28-day mortality

Inclusion Criteria:

• All patients admitted to the ICU with an infectious disease initiated within 48 hours of hospital admission and a microbiological positive result for bacteria

Exclusion Criteria:

• Patients with results considered as contamination according to the institutional protocol.
• Surgical wound and bloodstream infections.
• Microbiological isolation of only fungi.
• Vigilance cultures, such as anal, rectal, nasal, and axillary swabs.

Adult patients admitted to the ICU with an infectious disease initiated within 48 hours of hospital admission and with a positive microbiologic result.