[Analysis of influencing factors for pathogen culture result in patients with pyogenic spondylitis]

To investigate the effect of clinical factors on the pathogen culture results in the patients with pyogenic spondylitis, and to find out clinical controllable factors which could increase the positive rate of the pathogen culture.

A retrospective study reviewed 40 patients who were diagnosed with pyogenic spondylitis in Peking University First Hospital from January 2011 to July 2017. The patients were divided into two groups depending on the culture results, culture negative or culture positive. The influence of clinical uncontrollable factors [the patient's age, gender, predisposing factors, infection site except spine, visual analogue score (VAS), course of disease, spinal segment, white blood cell (WBC), (neutrophilic granulocyte)% (NE%), the incidence of systemic inflammatory response syndrome (SIRS), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), the incidence of paravertebral abscess] and controllable factors (prior antibiotics exposure within 2 weeks, tissue homogenate, surgical approach) on pathogen culture results were analyzed.

Of the 40 patients, 18 patients were female and 22 patients were male. Causative germ was identified in 24/40 patients (60.00%) and dominant by gram positive cocci (68.00%). For clinical uncontrollable factors, there was no significant difference between the two groups in the patient's age, gender, predisposing factors, infection site except spine, VAS, course of disease, spinal segment, WBC, NE% and the incidence of SIRS. ESR [(94.38±6.91) mm/h, P=0.023)], CRP [(64.74±13.51) mg/L, P=0.040], and the incidence of paravertebral abscess (75%, P=0.018) in culture negative group were lower in contrast to culture positive group. For clinical controllable factors, prior antibiotics exposure within 2 weeks (P=0.058, OR=4.030, 95%CI: 0.956-16.993) and tissue homogenate (P=0.014, OR=0.171, 95%CI: 0.042-0.695) were significantly associated with the pathogen culture result. Surgical approach was not significantly associated with pathogen culture result.

Patients with high level of ESR, CRP, and paravertebral abscess, would have high positive rate of pathogenic culture. Prior antibiotics exposure was associated with lower positive pathogen culture rate. Culture with tissue homogenate was more likely to find the causative germ, especially for patients without paravertebral abscess who had low level of ESR, CRP and prior antibiotics exposure.