Neumonía nosocomial causada por Staphylococcus aureus resistente a meticilina

Antimicrobial O-Alkyl Derivatives of Naringenin and Their Oximes Against Multidrug-Resistant Bacteria

New antimicrobial agents are needed to address infections caused by multidrug-resistant bacteria. Here, we are reporting novel O-alkyl derivatives of naringenin and their oximes, including novel compounds with a naringenin core and O-hexyl chains, showing activity against clinical strains of clarithromycin-resistant Helicobacter pylori, vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, and beta-lactam-resistant Acinetobacter baumannii and Klebsiella pneumoniae. The minimum inhibitory concentrations (MICs), which provide a quantitative measure of antimicrobial activity, were in the low microgram range for the selected compounds. Checkerboard assays for the most active compounds in combination with antibiotics revealed interactions that varied from synergistic to neutral.

[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.

Management of ventilator-associated pneumonia in a multidisciplinary intensive care unit: does trauma make a difference?

OBJECTIVE

Antibiotic exposure and timing of pneumonia onset influence ventilator-associated pneumonia (VAP) isolates. The first goal of this investigation was to evaluate whether trauma also influences prevalence of microorganisms.

DESIGN

A retrospective, single-center, observational cohort study.

SETTING

Multidisciplinary teaching ICU.

PATIENTS

Adult patients requiring mechanical ventilation identified as having VAP.

INTERVENTIONS

Retrospective evaluation of a prospective manual database.

MEASUREMENTS AND MAIN RESULTS

VAP isolates in a multidisciplinary ICU documented by quantitative respiratory cultures and recorded in a 42-month database were compared, based on the presence or absence of trauma. Causative microorganisms were classified in four groups, based on mechanical ventilation duration (> 5 days), and previous antibiotic exposure. One hundred eighty-three patients developed 196 episodes of VAP (98 trauma). Methicillin-sensitive Staphylococcus aureus (MSSA) was more frequent (34.5% vs. 11.5%, p < 0.01) in trauma, whereas methicillin-resistant Staphylococcus aureus (MRSA) was more frequent (2% vs. 11.5%, p < 0.01) in non-trauma. No significant differences were found between trauma and non-trauma patients regarding prevalence of other microorganisms. In trauma patients, MSSA episodes were equally distributed between early- and late-onset VAP (51% vs. 49%), but no MRSA episode occurred in the early-onset group.

CONCLUSIONS

Trauma influences the microbiology of pneumonia and it should be considered in the initial antibiotic regimen choice. Our data demonstrate that patients with trauma had a higher prevalence of MSSA, but the overall prevalence was sufficiently high to warrant S. aureus coverage for both groups. On the other hand, since no MRSA was isolated during the first 10 days of mechanical ventilation on trauma patients, MRSA coverage in these patients becomes necessary only 10 days after admission.

Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care

Hospital-acquired pneumonia is a common nosocomial infection, with significant morbidity and mortality, and represents a major therapeutic challenge to clinicians. The therapeutic approach must be patient-oriented and institution-specific. The specific risk factors of each patient, such as previous antibiotic exposure, underlying diseases, length of hospital stay and the local patterns of antimicrobial resistance, should guide physicians in their decision of the initial optimal empirical therapy. Delays in the initiation or inappropriate/inadequate initial therapy are related to increased mortality and worse outcomes. In responding patients, as soon as culture data are available, efforts should be made to change the initial broad spectrum antibiotic regimen to a more targeted one (de-escalation). The optimal duration of treatment is a matter of debate, but courses longer than 1 week are rarely justified.