[Impact on morbidity and costs of methicillin-resistant Staphylococcus aureus nosocomial pneumonia in intensive care patients]

[Risk factors of nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus]

BACKGROUND AND OBJECTIVE

To include a specific antibiotic in the empiric therapy, it is necessary to predict when a nosocomial pneumonia (NP) is caused by methicillin-resistant Staphylococcus aureus (MRSA). We have developed a model for the prediction of the probability of a NP being caused by MRSA, when the carrier status and the microbiological diagnosis are unknown.

PATIENTS AND METHODS

A retrospective case-control study (1999-2005) was designed. A univariate and multivariate logistic regression was performed to identify the risk factors for suffering a NP due to MRSA. Demographic factors, related to hospitalization, immunosuppression or neutropenia, to medication and severity were included.

RESULTS

Three hundred and sixty three patients (121 cases and 242 controls) were studied. The final model of multivariate logistic regression included an age>14 years (OR 7.4, CI 95% 1.5-37.4, P<.015), NP appearance>6 days after admittance (OR 4.1, CI 95% 2.4-7,1, P<.001), NP development excluding summers (OR 2.5, CI 95% 1.2-5.2, P<.015), respiratory diseases (OR 4.9, CI 95% 1.5-15.8, P<.007) and multilobar involvement (OR 4, CI 95% 2.3-7.2, P<.001).The probability of developing a pneumonia due to MRSA was studied for each of the possible combinations and subsequently classified in minor and major criteria.

CONCLUSIONS

MRSA coverage should be included in the empirical treatment of NP when: a) an adult patient (>14 years old) presents, at least, 2 major criteria or 1 major criterion together with 2 minor criteria, and b) a patient <14 years-old has 2 major criteria as well as 2 minor criteria.

Nosocomial methicillin resistant Staphylococcus aureus pneumonia - epidemiology and trends based on data of a network of 586 German ICUs (2005-2009)

The epidemiology of MRSA pneumonia varies across countries. One of the most import risk factors for the development of nosocomial MRSA pneumonia is mechanical ventilation. Methicillin resistance in S. aureus ventilator associated pneumonia (VAP) ranged between 37% in German, 54% in the US American and 78% in Asian and Latin American ICUs. In 2009, the incidence density of nosocomial VAP caused by MRSA was 0.28 per 1000 ventilation days in a network of 586 German ICUs. Incidences peaked in neurological and neurosurgical ICUs. Crude hospital mortality in studies performed after 2005 lay between 27% and 59% and attributable MRSA pneumonia mortality at 40%. Since 2005, US American and German data indicate decreasing trends for MRSA pneumonia. Measures to reduce MRSA pneumonia or to control the spread of MRSA include hand hygiene, standard and contact precautions, oral contamination with chlor hexidine, skin decontamination with antiseptics, screening, and (possibly) patient isolation in a single room.