Abstract
BACKGROUND/OBJECTIVES: Between January 2003 and December 2004, our hospital experienced a hospital-wide outbreak of ACBA, with a nosocomial incidence increase of 48% compared with 2002. The crude mortality for nosocomial acquisition of ACBA was 24%. The hospital-wide antibiogram for nosocomial ACBA demonstrated the following percentages of sensitive organisms: imipenem, 61%; ampicillinsulbactam, 21%; gentamicin, 14%; and quinolone, 13%. The approximately 2000 cardiovascular surgery (CVS) patients per year are admitted to surgical intensive care units, where 43% of ACBA cases are first identified. METHODS: Surveillance for SSIs is conducted concurrently with retrospective record review and post-discharge patient surveys. ACBA incidence is analyzed with CERNER Information System, a 48-hour interval as a marker of probable nosocomial acquisition, and no distinction for colonization or infection. Cases were patients with sternal SSI and positive ACBA cultures; controls were patients with sternal SSI without ACBA. Student's T test was used to compare continuous variables, and chi square was used to compare categorical variables. RESULTS: Between 2003 and 2004, nine patients (0.2% of all CVS; 11.7% of all sternal SSI) had post-operative sternal cultures positive for ACBA. ACBA was only found following a previous diagnosis of sternal SSI or dehiscence. ACBA was never found as the sole organism associated with SSI, and all case patients had debridement with subsequent open wounds before ACBA was cultured. A case control study demonstrated that colonization or infection with a secondary organism was statistically significant. Unexpectedly, blood loss was more severe in controls. All other variables (listed in table) were not significant. Patients with ACBA Patients without ACBA Significance Secondary organisms/infection 9/9 5/65 RR = 13.6 (5.9 – 31.6) Diabetes 6/9 40/68 NS Outcome-expired 2/7 10/67 NS Estimated blood loss 383.3 ± 19.5 504.4 ± 22.4 p = 0.14 Age 60.4 ± 7.8 62.1 ± 7.9 NS Pre-op days 2.7 ± 1.6 2.1 ± 1.5 NS Pre-op blood sugar 139.3 ± 11.8 122.5 ± 11.1 NS Body Mass Index 35.3 ± 5.8 32.6 ± 8.0 NS OR Time 3:39 ± 0:38 4:07 ± 1:19 NS Days -Surgery to Diagnosis 21.3 ± 4.6 23.6 ± 4.9 NS CONCLUSIONS: Although ACBA transmission is relatively common in the surgical intensive care setting, its contribution to diagnosis of SSI appears minimal. In our institution, ACBA associated with CVS SSI appears as secondary infection or colonization and appears as an opportunistic organism, possibly related to devitalized tissue.
Published Version
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