Osa Acinetobacter spp. Haemophilus spp. Moraxella catarrhalis Klebsiella spp. Escherichia coli Enterobacter spp. Proteus mirabilis Stenotrophomonas maltophilia Polymicrobial Culture negative Bacteremia 117 (58.8) 82 (41.2) 12 (6.0) 4 (2.0) 7 (3.5) 53 (26.6) 22 (11.1) 8 (4.0) 6 (3.0) 4 (2.0) 5 (2.5) 10 (5.0) 3 (1.5) 1 (0.5) 0 (0) 111 (55.8) 50 (25.1) 28 (14.1) HAP (n = 379) n ( ) 226 (59.6) 125 (33.0) 51 (13.5) 10 (2.6) 15 (4.0) 113 (29.8) 28 (7.4) 16 (4.2) 5 (1.3) 1 (0.3) 32 (8.4) 19 (5.0) 15 (4.0) 8 (2.1) 2 (0.5) 191 (50.4) 101 (26.6) 49 (12.9) VAP (n = 606) n ( ) 441 (72.8) 259 (42.7) 107 (17.7) 15 (2.5) 18 (3.0) 222 (36.6) 57 (9.4) 44 (7.3) 23 (3.8) 2 (0.3) 41 (6.8) 17 (2.8) 31 (5.1) 13 (2.1) 13 (2.1) 387 (63.9) 79 (13.0) 103 (17.0)HAP, Hospital-acquired pneumonia; HCAP, Healthcare-associated pneumonia; MRSA, Methicillin-resistant Staphylococcus aureus; MSSA, Methicillin-susceptible S.Lenvatinib mesylate aureus; VAP, Ventilator-associated pneumonia.Colchicine a Most commonly isolated pathogens reported (at least 2 in HCAP, HAP, or VAP).Discussion We found that in a population of patients with nosocomial pneumonia enrolled in a large, international, randomized, double-blind trial of therapies for MRSA, the frequencies of potentially MDR gram-negative pathogens were similar among patients with pneumonia classified as HCAP, HAP, or VAP.PMID:24914310 This suggests that, as recommended in ATS/ IDSA guidelines [1] empiric antibiotic regimens utilized for patients hospitalized with HCAP should be similar to those for HAP and VAP. It is widely accepted that pneumonia occurring after initiation of mechanical ventilation should initially betreated with antibiotics active against MDR pathogens. The rationale is straightforward: ventilated patients are cared for in settings with high antibiotic utilization and often receive antibiotics for other reasons. Both factors contribute to the selection of MDR pathogens when pneumonia occurs. Epidemiologic data in turn provide empiric support for these recommendations [27,28]. Though these rationales and supporting epidemiologic data are somewhat less compelling for pneumonias acquired in the hospital under circumstances other than mechanical ventilation, the extrapolation of VAP regimens to HAP patients has been widely recommended [1,29,30] and generally accepted. In contrast, recommendations to use antibiotic combinations originally chosen for VAP for patients with HCAP have met with more controversy [19], with some arguing that the HCAP classification itself lacks utility [22]. Our findings speak to both questions. Patients with HCAP were similar to those with HAP and VAP in several key respects: severity of illness; microbiology, particularly the frequency of potentially MDR pathogens; incidence of bacteremia; and short-term mortality. On the other hand, the higher burden of chronic conditions observed among HCAP patients in this study may justify its being a separate classification, particularly for investigators examining factors other than pathogen distribution. Our study has several limitations. Most importantly, rather than a survey of incident pneumonias, our data derive from a population recruited because of its perceived MRSA risk. Investigators may have taken into consideration factors not accounted for in the collected data that differentiate enrolled patients from other patients with VAP, HAP, and HCAP; e.g. airway specimen gram stain results, history of MRSA colonization, and even infections and colonization of nearby patients.