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Volume 32, Number 11—November 2026
Research
Microbial Etiology of Postoperative Spinal Fusion Infections and Factors Associated with Gram-Negative Infections, United States, 2021–2022
Table 4
Multinomial logistic regression analysis of predictors of monomicrobial gram-negative and other gram-positive spinal fusion surgical site infections compared with monomicrobial Staphylococcus aureus infections in study of microbial etiology of postoperative spinal fusion infections and factors associated with gram-negative infections, United States, 2021–2022*
| Characteristic | Monomicrobial gram-negative infections |
Other gram-positive infections |
|||
|---|---|---|---|---|---|
| OR (95% CI) | p value | OR (95% CI) | p value | ||
| Age |
1.03 (1.02–1.03) |
<0.001 |
1.01 (1.00–1.02) |
0.061 |
|
| BMI |
1.03 (1.02–1.04) |
<0.001 |
1.02 (1.00–1.04) |
0.043 |
|
| Male sex |
0.73 (0.63–0.84) |
<0.001 |
1.39 (1.06–1.82) |
0.019 |
|
| Outpatient surgery |
0.41 (0.18–0.96) |
0.040 |
0.88 (0.29–2.65) |
0.8 |
|
| Duration of surgery |
1.20 (1.16–1.24) |
<0.001 |
1.06 (1.00–1.13) |
0.066 |
|
| Surgical approach | |||||
| Anterior | Referent | Referent | |||
| Posterior | 1.01 (0.80–1.28) | >0.9 | 0.98 (0.66–1.46) | >0.9 | |
| Both |
0.86(0.53-1.39) |
0.5 |
1.31 (0.57–2.99) |
0.5 |
|
| ASA class | |||||
| 1 | Referent | Referent | |||
| 2 | 4.83 (1.05-22.3) | 0.044 | 2.10 (0.27–16.5) | 0.5 | |
| 3 | 7.04 (1.53-32.3) | 0.012 | 2.33 (0.30–18.1) | 0.4 | |
| 4 |
15.4 (3.29-72.0) |
<0.001 |
1.96 (0.24–16.3) |
0.5 |
|
| Diabetes |
1.20 (0.90–1.60) |
0.2 |
|||
| Wound class | |||||
| Clean | Referent | Referent | |||
| Clean-contaminated | 1.74 (1.06–2.87) | 0.029 | 1.13 (0.43–2.97) | 0.8 | |
| Contaminated | 2.21 (0.66–7.33) | 0.2 | 0.00 (0.00-0.00) | <0.001 | |
| Dirty |
1.76 (0.80–3.89) |
0.2 |
0.00 (0.00-0.00) |
<0.001 |
|
| Spinal level | |||||
| Axis-atlas/cervical | Referent | Referent | |||
| Cervical/dorsal/dorsolumbar | 1.11 (0.77–1.61) | 0.6 | 0.59 (0.32–1.08) | 0.087 | |
| Dorsal/dorsolumbar | 1.27 (0.99–1.63) | 0.056 | 0.49 (0.32–0.74) | <0.001 | |
| Lumbar/lumbosacral |
1.51 (1.22–1.85) |
<0.001 |
0.44 (0.32–0.62) |
<0.001 |
|
| Trauma |
1.91 (1.38–2.64) |
<0.001 |
1.04 (0.57–1.89) |
0.9 |
|
| Closure | |||||
| Intentionally left open | Referent | Referent | |||
| Fully closed or partial |
1.07 (0.50–2.33) |
0.9 |
2.33 (0.30–18.1) |
0.4 |
|
| Timing of infection, days from procedure |
0.97 (0.96–0.97) |
<0.001 |
0.99 (0.98–1.00) |
0.11 |
|
| Depth of infection | |||||
| Superficial | Referent | Referent | |||
| Deep | 0.88 (0.74–1.05) | 0.15 | 0.95 (0.68–1.33) | 0.8 | |
| Organ space |
0.85 (0.70–1.03) |
0.10 |
1.14 (0.79–1.66) |
0.5 |
|
| Emergency |
0.99 (0.75–1.31) |
>0.9 |
1.50 (0.93–2.39) |
0.093 |
|
| Use of scope | 2.55 (0.49–13.1) | 0.3 | 0.00 (0.00-0.00) | <0.001 | |
*ORs represent the relative odds of monomicrobial gram-negative infections or other gram-positive infection compared with the reference group of monomicrobial Staphylococcus aureus spinal fusion surgical site infection. ASA level 5 was removed because of insufficient numbers. ASA, American Society of Anesthesiologists; BMI, body mass index; OR, odds ratio.