Table 3

Association between surgical site infections and duration, timing, and antibiotic prophylaxis agent, adjusted for age, sex, ASA score, and duration of operation

Predictor variable
N
Infection
Rate*
Relative risk









Crude
95% CI
Adjusted**
95% CI

Duration of antibiotic prophylaxis







     None
167
5
3.0
1.00
Reference
1.00
Reference
     1 day
1159
12
1.0
0.34
0.12–0.97
0.30
0.10–0.88
     >1 day
813
9
1.1
0.36
0.12–1.09
0.32
0.10–0.98
Time of first antibiotic dose administration







     None
167
5
3.0
1.00
Reference
1.00
Reference
     >1 hour preoperatively
1004
8
0.8
0.26
0.08–0.81
0.22
0.07–0.70
     ≤ 1 hour preoperatively or interoperation
814
9
1.1
0.36
0.12–1.09
0.33
0.11–1.02
     Postoperatively
154
4
2.6
0.86
0.23–3.28
0.78
0.20–3.00
Antibiotic agent







     None
167
5
3.0
1.00
Reference
1.00
Reference
     Single dose combination metronidazole and gentamicin
766
8
1.0
0.34
0.11–1.06
0.28
0.09–0.90
     Combination metronidazole and gentamicin within 1 day
130
1
0.8
0.25
0.03–2.18
0.22
0.03–1.98
     Combination metronidazole and gentamicin > 1 day
370
4
1.1
0.35
0.09–1.34
0.29
0.08–1.12
     Others***
706
8
1.1
0.37
0.12–1.15
0.37
0.12–1.15

* Rate = infections/100 operations

** Adjusted for age, sex, ASA score, and duration of operation

*** Others: Penicillin, amoxicillin, amoxicillin/clavulanate, ampicillin, cloxacillin, cefazolin, cephalexin, cefotaxime, ceftriaxone, ceftazidime, cefdinir, cefoxitin, ofloxacin, norfloxacin, cotrimoxazole, chloramphenical, fosfomycin, clindamycin, and amikacin.

Kasatpibal et al. BMC Infectious Diseases 2006 6:111   doi:10.1186/1471-2334-6-111