Background and Goal of Study: Bacterial resistance to antibiotics is a daily concern in intensive care units and represent a major public health challenge in every country, with the emergence of pan-drug resistant bacteria. However, few data are available concerning clinical consequences of in-vitro defined resistances. This wide retrospective study aimed at comparing in-hospital mortality of intensive care infections, according to bacterial resistance profile.
Materials and Methods: Health-care associated infections are monitored in a national prospective registry, managed by the Investigation and Surveillance of Healthcare-Associated Infections Network (RAISIN). Data included in the registries from 2000 to 2013 were analyzed. Sub-group analysis was performed using one-way ANOVA.
Results and Discussion: Among the 87931 patients retrieved, 10001 presented a health-care related infection, including 3092 resistant germs (36.7% (95%CI [35.7-37.7]). Infections were caused by gram negative bacilli in 54.7% (95%CI [53.6 - 54.8]) of cases and gram positive cocci in 30.0% (95%CI [29.0-31.0]) of cases. Gram negative bacilli presented the highest rate of resistance (52.8% 95%CI [51.3-54.3]), in comparison to Gram positive cocci (48.1% 95%CI [46.3 - 49.9]).
In-hospital mortality was higher in case of infection if the germ had antibiotic resistance (51.9% 95%CI [50.1-53.7] vs 45.5% 95%CI [44.2-46.8], p< .001) and critical care length of stay was longer (33.5 ± 26.0 vs 29.5 ± 22.9 days, p< .001). These results remained significant after SAPS II matching (p< .001), and were identical in the gram negative bacilli and gram positive cocci sub-groups.
Comparing patients according to their origin before admission, no difference of mortality was found. However, more resistant bacteria were found in patients coming from intensive care units (45.8% 95%CI [41.5-50.1]) or conventional units (39.3% 95%CI [37.6-41]) than from home (33.5% 95%CI [32.1-34.9]) or long term care or rehabilitation centres (33.5% 95%CI [28.8-38.2]).
Central venous catheter infections were associated to the highest rate of resistance ((75.0% 95%CI [63.2-86.8]), in comparison to pneumopathies (48.2% 95%CI[46.6-49.8]), bacteraemia (48.7% 95%CI[45.3-52.1]) and urinary tract infections (40.8% 95%[37.5-44.1]).
Conclusion: Bacterial resistance is associated with a higher ICU mortality and increased length of stay, regardless of germ or origin of the patient.

Influence of bacterial resistance on mortality in intensive care units: a registry study from 2000 to 2013