Background Patients hospitalised in the Intensive Care Unit (ICU) are often intubated and thus their lower airways are exposed to colonisation by flora in ambient air. Colonisation is often followed by nosocomial pneumopathies; prophylactic antibiotics are used to prevent them, usually associated with the emergence of multi-drug-resistant strains (MDR), the cause of nosocomial infections. One common etiological agent involved in lung disease is Staphylococcus aureus (SA).

Purpose To see if there is a correlation between the use of certain antimicrobial agents in the emergency section and the emergence of resistant SA strains isolated from patients hospitalised in the same ward. To establish the resistance profile of strains of SA in theICU, to guide the selection of antimicrobial drugs and to prevent selection of MDR strains.

Materials and methods We collected samples of tracheal secretions from 130 endotracheal intubated patients admitted to the ICU ward between 1.03.2012–30.06.2013 and conducted microbiological testing. We identified 138 strains of SA and we tested their susceptibility to the following antimicrobial agents: amoxicillin with clavulanic acid, oxacillin, chloramphenicol, clarithromycin, ciprofloxacin, moxifloxacin, linezolid, rifampicin, tetracycline, teicoplanin, tigecycline and vancomycin.

Hospital pharmacy records provided data on the use of antimicrobial agents (number of vials) in ICU.

Results The prevalence of Staphylococcus respiratory infections ranged from 17% to 25% in every 3 month period and it correlated with the consumption of moxifloxacin (r = 0.8899, p = 0.0175), linezolid (r = 0.8494, p = 0.0323) and tigecycline (r = 0.5534, p = 0.0774).

SA resistance to chloramphenicol was negatively correlated with the consumption of teicoplanin (r = -0.7625, p = 0.0779). Mean antibiotic resistance (MAR) was significantly correlated with the consumption of moxifloxacin (r = 0.4018, p = 0.0983) and inversely correlated with meropenem consumption (r = -0.4517, p = 0.0599).

Isolated SA strains were resistant to: ampicillin (100%), penicillin (94.26%), amoxicillin with clavulanic acid (69.32%), oxacillin (67.63%), clarithromycin (54.88%), rifampicin (58.82%), tetracycline (57.89%), ciprofloxacin (45.83%), chloramphenicol (24.51%). We found low resistance to teicoplanin (3.01%), linezolid (2.22%) and tigecycline (1.96%).

Conclusions The use of certain antimicrobial agents in ICU correlates with staphylococcal lower respiratory tract infections and the emergence of multidrug-resistant strains.

The therapeutic management of patients admitted to ICU requires teams of clinicians, microbiologists, epidemiologists, hygienists, pharmacists, even hospital economists, to benefit each other and especially patients.

No conflict of interest.