Comprehensive treatment algorithm of postoperative spinal implant infection

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Implant-associated Infection After Pediatric Spine Deformity Surgery: Is Removal of Hardware Indicated?

BACKGROUND

Postoperative spinal implant infection following pediatric spinal surgery often presents a management dilemma. We aimed to characterize our experience in this cohort of patients, hoping to provide further insight when approaching these challenging cases.

METHODS

A retrospective, observational study was performed of all children who underwent spinal surgery from January 2015 to June 2021 in a tertiary pediatric spinal surgery referral center in Queensland, Australia. Records were reviewed to identify cases of postoperative surgical site infection, with particular focus on children with infection directly involving implants. Preoperative prophylaxis, microbiology, clinical course and outcomes were analyzed.

RESULTS

A total of 580 children underwent 933 procedures during the study period. The most common pathology requiring surgery was idiopathic scoliosis in 257 children (44.3%) followed by neuromuscular scoliosis in 192 children (33.1%). There were 35 cases of surgical site infection (6.03%), and 9 were implant-associated (1.55%). Infection rate among children with neuromuscular spinal deformity was almost 3-fold higher (11.5%) than idiopathic (3.89%). Methicillin-sensitive Staphylococcus aureus was the most commonly isolated organism (n = 15). Four implant-associated infections were successfully managed with retention of implant; all were diagnosed within 32 days (median = 20 days) and cultured either Staphylococcus aureus or Pseudomonas aeruginosa . Conversely, infections that necessitated implant removal had a more indolent onset (median = 175 days), and more often cultured Cutibacterium acnes and coagulase-negative Staphylococci .

CONCLUSIONS

Postoperative spinal implant infection can be treated successfully with hardware retention in select cases. Earlier presentation and recognition appear to be associated with better rates of retention and are linked to certain organisms. Further exploration of specific preventative strategies may be key in preventing devastating late-onset infections.

Tissue sampling is non-inferior in comparison to sonication in orthopedic revision surgery

BACKGROUND

The aim of this study was to assess the role of sonication fluid cultures in detecting musculoskeletal infections in orthopedic revision surgery in patients suspected of having peri-prosthetic joint infection (PJI), fracture-related infections (FRI), or postoperative spinal implant infections (PSII).

METHODS

Between 2016 and 2019, 149 cases with a data set including sonication fluid cultures and tissue specimen and histological analysis were included. Accuracy of each diagnostic tool as well as the influence of antibiotic therapy was analyzed. Pathogens identified in the sonication cultures and in the associated tissue samples were compared based on the matching of the antibiograms. Therapeutic benefits were then assessed.

RESULTS

Of 149 cases, 43.6% (n = 65) were identified as PJI, 2.7% (n = 4) as FRI, 12.8% (n = 19) as PSII, 6.7% (n = 10) as aseptic non-union, and 34.2% (n = 51) as aseptic implant loosening. The sensitivity and specificity of tissue and synovial specimens showed no significant difference with respect to sonication fluid cultures (sensitivity/specificity: tissue: 68.2%/96.7%; sonication fluid cultures: 60.2%/98.4%). The administration of antibiotics over 14 days prior to microbiological sampling (n = 40) resulted in a lower sensitivity of 42.9% each. Histological analysis showed a sensitivity 86.3% and specificity of 97.4%. In 83.9% (n = 125) of the cases, the results of sonication fluid cultures and tissue specimens were identical. Different microorganisms were found in only four cases. In 17 cases, tissue samples (n = 5) or sonication (n = 12) were false-negatives.

CONCLUSION

Sonication fluid culture showed no additional benefit compared to conventional microbiological diagnostics of tissue and synovial fluid cultures. Preoperative administration of antibiotics had a clearly negative effect on microbiologic test accuracy. In over 83.9% of the cases, sonication fluid and tissue cultures showed identical results. In the other cases, sonication fluid culture did not further contribute to the therapy decision, whereas other factors, such as fistulas, cell counts, or histological analysis, were decisive in determining therapy.

[Common infectious challenges of the thoracic and lumbar spine : Spondylodiscitis and postoperative wound infection]

Spondylodiscitis and postoperative wound infections are the most frequent infectious diseases of the thoracic and lumbar spine. Every spinal surgeon will come into contact with such patients during his or her career. Knowledge particularly of the diagnostics, conservative and surgical treatment as well as microbiological considerations of antibiotic treatment are therefore of particular importance and are explained in this article.

Incidence, risk factors and clinical course of pyogenic spondylodiscitis patients with pulmonary embolism

Purpose

In patients with pyogenic spondylodiscitis, surgery is considered the treatment of choice to conduct proper debridement, stabilise the spine and avoid extended bed rest, which in turn is a risk factor for complications such as deep vein thrombosis and pulmonary embolism.

Methods

We conducted a retrospective clinical study with analysis of a group of 99 patients who had undergone treatment for pyogenic discitis at our institution between June 2012 and August 2017. Included parameters were age, sex, disease pattern, the presence of deep vein thrombosis, resuscitation, in-hospital mortality, present anticoagulation, preexisting comorbidities, tobacco abuse, body mass index, microbiological germ detection and laboratory results.

Results

Among the analysed cohort, 12% of the treated patients for pyogenic spondylodiscitis suffered from a radiologically confirmed pulmonary embolism. Coronary heart disease (p < 0.01), female sex (p < 0.01), anticoagulation at admission (p < 0.01) and non-O blood type (p < 0.001) were associated with development of pulmonary embolism. Pulmonary embolism was significantly associated with resuscitation (p < 0.005) and deep vein thrombosis (p < 0.001). Neurosurgery was not associated with increased risk for pulmonary embolism compared to conservative-treated patients (p > 0.05).

Conclusion

Surgery for pyogenic spondylodiscitis was not associated with an elevated risk of pulmonary embolism in our analysis. However, we describe several risk factors for pulmonary embolism in this vulnerable cohort. Prospective studies are necessary to improve prevention and postoperative management in patients with pyogenic spondylodiscitis.