Choosing the right antibacterial agent. Is 'newer' always better?

Identification of Early Predictors for Post-Traumatic Pneumonia

We demonstrated that the standard clinical criteria of fever, leukocytosis, purulent sputum, and infiltrate on chest radiograph are nonspecific for the diagnosis of post-traumatic pneumonia, and only ∼50 per cent of patients with these conditions have pneumonia. Quantitative cultures of bronchoalveolar lavage effluent will differentiate pneumonia (requiring antibiotic therapy) from systemic inflammatory response syndrome (not requiring antibiotics). Early identification of patients at risk for pneumonia can target populations for clinical research. Because risk factors for pneumonia when diagnosed by quantitative cultures have not been defined we reviewed our recent experience to identify variables predictive of pneumonia. Patients over a 22-month period who survived >48 hours were identified from the trauma registry. Pneumonia was defined as growth of ≥105 organisms per milliliter in the bronchoalveolar lavage effluent. Risk factors evaluated included injury severity and severity of shock. There were 7503 patients (75% with blunt and 25% with penetrating injuries). The incidence of pneumonia was 6 per cent (7% of patients with blunt and 2% of patients with penetrating injuries). Logistic regression analysis identified age; Glasgow Coma Scale score; Injury Severity Score; transfusion requirements during resuscitation; spinal cord injury; chest injury severity; and emergent femur fixation, craniotomy, and laparotomy as being independent predictors of pneumonia. We conclude that multiple risk factors, which are all able to be determined early after injury, are predictive of post-traumatic pneumonia. Prompt identification of this high-risk group of patients allows prognostic considerations relative to patient management schemes and targets populations for prophylactic measures or immunomodulation.

Utility of Gram's stain and efficacy of quantitative cultures for posttraumatic pneumonia: a prospective study

OBJECTIVE

This prospective trial examined the efficacy of using bronchoalveolar lavage (BAL) for the diagnosis of pneumonia (PN) and the utility of Gram's stain (GS) for dictating empiric therapy.

SUMMARY BACKGROUND DATA

Posttraumatic nosocomial PN remains a significant cause of morbidity and mortality. However, its diagnosis is elusive, especially in multiply injured patients. The systemic inflammatory response syndrome of fever, leukocytosis, and a hyperdynamic state is common in trauma patients, especially patients with pulmonary contusion. Bronchoscopy with BAL with quantitative cultures of the lavage effluent may distinguish between PN and systemic inflammatory response syndrome, and GS of the lavage effluent may guide empiric therapy before quantitative culture results.

METHODS

Mechanically ventilated trauma patients with a clinical diagnosis of PN (fever, leukocytosis, purulent sputum, and new or changing infiltrate on chest radiograph) underwent bronchoscopy with BAL. Effluent was sent for GS and quantitative cultures. The diagnostic threshold for PN was > or =10(5) colony-forming units (CFU)/mL, and antibiotics were continued. Antibiotics were stopped for < 10(5) CFU/mL and the diagnosis of systemic inflammatory response syndrome was made. Causative organisms for PN were compared to GS.

RESULTS

Over a 2-year period, 232 patients underwent 443 bronchoscopies with BAL (71% men, 29% women; mean age, 41). The mean injury severity score was 30. Sixty percent of the patients had pulmonary contusion, and 59% were cigarette smokers. The overall incidence of PN was 39% and was no different regardless of the number of BALs a patient had. The false-negative rate of BAL was 7%. GS identified gram-positive organisms in 80% of patients with gram-positive PN and 40% of patients with gram-negative PN. GS identified gram-negative organisms in 52% of patients with gram-positive PN and 77% with gram-negative PN. The duration of the intensive care unit stay relative to the timing of BAL was beneficial for guiding empiric therapy. BAL in week 1 primarily identified Haemophilus influenzae and gram-positive organisms; Acinetobacter sp. and Pseudomonas sp. were more common after week 1.

CONCLUSIONS

Bronchoscopy with BAL is an effective method to diagnose PN and avoids prolonged, unnecessary antibiotic therapy. Empiric therapy should be adjusted to the duration of the intensive care unit stay because the causative bacteria flora changes over time. GS of BAL effluent correlates poorly with quantitative cultures and is not reliable for dictating empiric therapy.

Using bronchoalveolar lavage to distinguish nosocomial pneumonia from systemic inflammatory response syndrome: a prospective analysis

OBJECTIVE

Ventilator-associated pneumonia (PN) is difficult to distinguish from trauma-induced systemic inflammatory response syndrome (SIRS), especially in patients with multiple injuries. Previous work using bronchoscopy and quantitative cultures demonstrated significant bacterial growth in about one-third of patients with clinical evidence of PN. In this prospective study, antibiotic therapy for PN was based solely on quantitative bronchoalveolar lavage (BAL) cultures.

METHODS

Mechanically ventilated trauma patients underwent bronchoscopy with BAL when they developed clinical evidence of PN: fever (temperature > 100.5 degrees F), white blood cells > 10,000 or > 10% immature forms, purulent sputum, and new or changing infiltrate on chest roentgenogram. Patients with other infections or those receiving antibiotics for any other reason were excluded. Empiric antibiotic therapy for PN was started at the time of BAL. If the quantitative cultures revealed > or = 10(5) colony-forming units (CFU)/mL, that patient was defined as having PN and was treated. If the cultures revealed < 10(5) CFU/mL, that patient was defined as having SIRS, and empiric therapy was stopped.

RESULTS

Forty-three patients (88% blunt, 12% penetrating) underwent bronchoscopy with BAL 55 times. Mean age was 40 and Injury Severity Score was 25. Twenty patients had > or = 10(5) CFU/mL (47%) and 23 had < 10(5) CFU/mL (53%). There were no differences in age, Injury Severity Score, temperature, white blood cell count, or ventilator days before BAL between groups. Sixty-five percent of those with SIRS improved after empiric therapy was stopped (average 3.3 days), and 35% underwent repeat BAL. Three patients with the initial diagnosis of SIRS developed PN (13% of SIRS). Mortality for PN was 15%, compared with 17% for SIRS; no deaths were related to antibiotic therapy.

CONCLUSIONS

SIRS, which can mimic PN, is common in trauma patients. These entities can be distinguished by bronchoscopy with BAL. Basing antibiotic therapy solely on quantitative BAL cultures is efficacious in trauma patients.