Incidence and microbiological profile of surgical site infections following management of open fractures

Background: Surgical site infection (SSI) is a usual complication following management of open fractures. It has been described a high prevalence of Gram-negative bacilli (GNB) in these infections, especially A. baumanii.

Objective: To describe incidence and microbiological profile of SSI following management of open fractures in a 5-year period at a center for orthopedics care in São Paulo, Brazil.

Methods: Retrospective analysis of data from patients with open fractures treated from January 2005 to December 2009. Inicial treatment included surgical debridement, external or internal fixation and therapy with cefazolin (fractures Gustillo type 1) or clindamycin plus gentamicin (Gustillo types 2 or 3). Determination of incidence rate included those with diagnosis of SSI related to topography of fracture, which followed the criteria defined by the Centers for Disease Control and Prevention. Cumulative antibiograms were prepared according to standards recommended by the Clinical and Laboratory Standards Institute, and included only isolates obtained from specimens collected after antisepsis and surgical debridement.

Results: During this period, 1044 patients with open fractures were treated and 128 had diagnosis of SSI, with an incidence of 12% for this complication. In 81% of these cases, the causative agent was identified, with an average of 1.7 agent per patient. Of the 185 isolates, 49% were Gram-positive cocci, 48%, GNB and 3%, fungi. The most frequent agents were S. aureus (19%), A. baumanii (17%), Coagulase-negative Staphylococci (14%), E. faecalis (11%), P. aeruginosa (8%) and E. cloacae (7%). Table 1 shows antimicrobial susceptibilities.

Conclusions: Incidence of SSI related to management of open fractures was 12%. S. aureus and A. baumanii were the most frequent agents. Isolates showed low antimicrobial susceptibility rates. In this context, treatment of these SSI represents a challenge to all professionals involved in its management.

Table 1 - Antimicrobial susceptibility profiles of isolates

Pathogen/ Tested Antimicrobial	Antimicrobial susceptibility (%)
S. aureus (n=36)
Cephalotin	14
Ciprofloxacin	9
Clindamycin	8
Levofloxacin	19
Linezolid	100
Meticillin	25
Rifampicin	62
SMT/TMP	33
Vancomycin	100
A. baumanii (n=32)
Amikacin	7
Ampicillin/Sulbactan	80
Cefepime	4
Ceftazidime	4
Ceftriaxone	4
Ciprofloxacin	4
Gentamycin	28
Imipenem	57
SMT/TMP	12
Coagulase-negative Staphylococci (n=26)
Cephalotin	zero
Ciprofloxacin	14
Clindamycin	13
Levofloxacin	12
Linezolid	100
Meticillin	11
Rifampicin	88
SMT/TMP	18
Vancomycin	100
E. faecalis (n=20)
Ampicillin	100
Gentamycin	50
Linezolid	100
Vancomycin	76
P. aeruginosa (n=14)
Amikacin	90
Aztreonan	56
Cefepime	62
Ceftazidime	60
Ciprofloxacin	75
Gentamycin	78
Imipenem	78
Piperacillin/Tazobactan	67
E. cloacae (n=13)
Amikacin	100
Aztreonan	75
Cefepime	87
Ceftazidime	75
Ciprofloxacin	80
Gentamycin	93
Imipenem	100