Matt Harmon

187 Chapter nine Detailed description of the distribution of pathogenic organisms is important as it can help guide empiric antibiotic treatment. Inappropriate antibiotic therapy occurs in a significant portion of cardiac arrest patients and is associated with increased ICU-stay. 1 Our results are in line with previous descriptions of pathogen distribution, showing that Staphylococcus aureus is the most commonly cultured pathogen. 1-4 In our study, gram-negative pathogens in pneumonia were the most commonly cultured. Although we did not prospectively document aspiration, it can be hypothesized that aspiration may have contributed to the high incidence of pneumonia in this patient population. Only a limited number of anaerobic micro- organisms were found in this study, likely due to the fact that anaerobic cultures are not routinely performed on sputum. Also, Pseudomonas aeruginosa was rarely cultured. Taken together, depending on local resistance patterns, a cephalosporin of the 2 nd or 3 rd generation may be a reasonable empiric approach. In line with this, the incidence of pneumonia was lower in centers that used a cephalosporin of the 2 nd or 3 rd generation as prophylaxis. Staphylococcus aureus is the most commonly cultured pathogen in sputum. 1-4 This finding has similarities to the observation that Staphylococcus aureus is also frequently cultured in trauma patients. 15-17 Also, as relatively large proportion of patients receive antibiotic prophylaxis with limited activity against Staphylococcus aureus , this micro-organism may be selected due to antibiotic use. In general, a high incidence of nosocomial infections is thought to be associated with immune paralysis 18 , which occurs within an hour after trauma. 19 In line with this, we previously showed that the ability of immune cells to react to gram-positive and gram-negative bacterial components is reduced following cardiac arrest, irrespective of the temperature management regime. 6 Bacteremia was less common, comprising 4% of patients in this study. This is lower than previously reported. 2-4 Staphylococcus aureus was the most commonly cultured pathogen in our study compared to Escherichia coli in a previous study. 2 Only 2 of the 8 patients with Staphylococcus aureus bacteremia had positive sputum cultures with Staphylococcus aureus . It remains unclear whether the concept of the use of prophylactic antibiotics reduces infection risk. In a systematic review, prophylaxis with an SDD regime has been shown to reduce nosocomial infections. 20 Specifically, in the group of cardiac arrest patients, prophylaxis was found to reduce the incidence of early pneumonia. 11 This finding was partly confirmed in a prospective randomized pilot trial of 83 patients with cardiac arrest, in which prophylactic versus clinically driven antibiotics decreased the rate of positive cultures from the lower respiratory tract, although outcomes did not improve. 5 However, in the same cohort, we previously reported that infectious complications are associated with increased mortality following cardiac arrest. 5 The potential benefits of antibiotic prophylaxis need to be weighed against potentially increased