Infections of the Thorax
Mortality for thoracic injury in the pre-antibiotic era was 63% but decreased to 2% during the Korean conflict, reflecting benefits of surgery and antibiotics. Thoracic trauma mortality rates in Vietnam and Bosnia were 3–4%.[46,47] Body armor has further decreased mortality from thoracic wounds. However, in past conflicts, the majority of HE trauma reprised gunshot and grenade injuries, while currently, fragmentation devices (IEDs and rocket propelled grenades) predominate. Between 2002 and 2008, 4.9% of HE injuries in Iraq and Afghanistan were sustained thoracic injury, half civilians and half combatants. Penetrating trauma accounted for 40% of all injuries, second only to blast (45.8%). Civilian penetrating trauma rates exceeded combatants (64 vs 36%), probably due to the lack of protective body armor.
Historically, HE thoracic injuries of war have had higher infection rates (5–9%) than LE civilian injuries (3%). Delayed treatment and polytrauma (additional blast and burn components) may contribute this the discrepancy. Thoracic infections accounted for 5–10% of HE injuries in World War II (primarily empyema), as penicillin was being introduced, dropping to 2% during the Vietnam War. A recent single-center review of all HE trauma infections from Iraq revealed 14% with thoracic injuries, 23% with associated infection.[50,51] LE (58.8%) and VLE (41.2%) penetrating trauma represented the primary causes of the 1.5% of civilian patients with post-traumatic empyema in a Turkish hospital. Pathogens commonly described include coagulase-negative Staphylococcus if a tube thoracostomy is in place. In infection developing over 48 h after injury, coagulase-negative Staphylococcus, S. aureus (including methicillin-resistant), Gram-negative facultative aerobes and anaerobes are all know to cause infection. Both Enterococcus and Candida spp. have been described when the abdominal compartment is involved.
Historically, the greatest risk of infection in penetrating thoracic injury is retained hemothorax.[50,54,55] Consequently, tube thoracostomy is used most often in the management of thoracic trauma to promote lung expansion and remove blood to minimize infection. Some studies cite conditions of tube insertion (prehospital vs hospital) as having a negative effect on infection, while a more recent study found no difference. Bacterial causes of infection in penetrating thoracic injury include Gram-positive, Gram-negative and anaerobic organisms, with S. aureus most commonly cited. Antimicrobial prophylaxis has not definitively improved outcomes when used before, during or after tube thoracostomy, probably because bacterial contamination occurs long before thoracostomy placement.
Prophylactic antibiotics ideally should reduce empyema and pneumonia, while inhibiting the emergence of antimicrobial resistance. Six randomized placebo-controlled trials failed to show that prophylactic antibiotics statistically reduced infection rates. A study of post-thoracostomy cefazolin administration demonstrated no reduction in empyema or pneumonia incidence. However, a recent meta-analysis (including the cited study), demonstrated an overall reduction in empyema when primarily cephalosporins were administered for 24 h following thoracostomy placement. Duration of therapy remains in question, however; if adequate source control and drainage is achieved, 24 h is likely adequate. In summary, for thoracic injury (Table 4), based upon consensus opinion, one prospective trial and a meta-analysis (BII level of evidence), we recommend cefazolin for use with empyema in the presence of tube thoracostomy. In addition, aminoglycosides should be avoided in this setting. Duration of therapy based upon one prospective trial and a meta-analysis, should be no longer than 24 h (BII).
Antibiotic Therapy for Infection
Empyema is often present and is caused by skin flora which are probably introduced by tube thoracostomy placement or immediately following trauma. Furthermore, pneumonia is also often present as a complication of injury or concomitant ventilatory support. Source control and drainage of fluid is appropriate for all empyemas, as is performing a pH test, Gram stain and culture of available fluid. Although Maxwell et al. found no benefit in terms of reduced incidence of empyema or pneumonia in their small study, first-generation cephalosporin is preferred in this setting or when staining indicates Gram-positive organisms. Gram-negative coverage should be added if Gram stain is indicative, or for infections developing over 48 h after hospital admission. Enteric contamination, including B. fragilis, can occur in the polytrauma patient, and should be treated with fluoroquinolones or third-generation cephalosporins with metronidazole; alternatively ticarcillin/clavulanic acid, piperacillin/tazobactam or moxifloxacin monotherapy can be used. Nosocomial pathogens should be targeted in any patient with sepsis or receiving antimicrobials after 48 h or with signs of systemic inflammatory response syndrome over 48 h following surgery. In these cases, carbapenems, advanced cephalosporins (ceftazidime and cefepime) with metronidazole, or aztreonam with metronidazole provide good coverage. Clindamycin, while useful for thoracic cavity infections, may not be adequate for B. fragilis owing to resistance. Coverage for Enterococcus spp. and Candida spp. should also be considered for contaminated IAIs penetrating into the thoracic cavity. Hospital-specific antibiograms can also aid in empiric antimicrobial selection. Guidelines regarding duration of therapy recommend 3 weeks, although if adequate drainage is achieved earlier, courses may be shortened. In summary, or empiric treatment of infections of the thorax in the setting of traumatic injury (Table 4) or for infections that develop greater than 48 h after admission and tube thoracostomy (i.e., delayed), based upon consensus opinion and meta-analysis (BIII level of evidence), we recommend vancomycin combined with an antipseudomonal third-generation cephalosporin or carbapenem with treatment for 21 days (BIII level of evidence).
Expert Rev Anti Infect Ther. 2011;9(1):81-96. © 2011 Expert Reviews Ltd.
Cite this: Prophylaxis and Treatment of Infections Associated with Penetrating Traumatic Injury - Medscape - Jan 01, 2011.