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BackgroundPercutaneous drainage (PCD) and surgical intervention are two primary treatment options for iliopsoas abscess (IPA). However, there is currently no consensus on when to use PCD or surgical intervention, especially in patients with gas-forming IPA. This study compared the characteristics of patients with gas-forming and non-gas forming IPA and their mortality rates under different treatment modalities. An algorithm for selecting appropriate treatment for IPA patients is proposed based on our findings.MethodsEighty-eight IPA patients between July 2007 and February 2013 were enrolled in this retrospective study. Patients < 18 years of age or with an incomplete course of treatment were excluded. Demographic information, clinical characteristics, and outcomes of different treatment approaches were compared between gas-forming IPA and non-gas forming IPA patients.ResultsAmong the 88 enrolled patients, 27 (31%) had gas-forming IPA and 61 (69%) had non-gas forming IPA. The overall intra-hospital mortality rate was 25%. The gas-forming IPA group had a higher intra-hospital mortality rate (12/27, 44.0%) than the non-gas forming IPA group (10/61, 16.4%) (P < 0.001). Only 2 of the 13 patients in the gas-forming IPA group initially accepting PCD had a good outcome (success rate = 15.4%). Three of the 11 IPA patients with failed initial PCD expired, and 8 of the 11 patients with failed initial PCD accepted salvage operation, of whom 5 survived. Seven of the 8 gas-forming IPA patients accepting primary surgical intervention survived (success rate = 87.5%). Only 1 of the 6 gas-forming IPA patients who accepted antibiotics alone, without PCD or surgical intervention, survived (success rate = 16.7%). In the non-gas forming IPA group, 23 of 61 patients initially accepted PCD, which was successful in 17 patients (73.9%). The success rate of PCD was much higher in the non-gas forming group than in the gas-forming group (P <0.01).ConclusionsBased on the high failure rate of PCD and the high success rate of surgical intervention in our samples, we recommend early surgical intervention with appropriate antibiotic treatment for the patients with gas-forming IPA. Either PCD or primary surgical intervention is a suitable treatment for patients with non-gas forming IPA.

Purpose: The IFN-stimulated gene 15 (ISG15)-and ubiquitin-conjugation pathways play roles in mediating hypoxic and inflammatory responses. To identify interaction(s) between these two tumor microenvironments, we investigated the effect of ISG15 on the activity of the master hypoxic transcription factor HIF-1a.Experimental Design: IFN and desferoxamine treatments were used to induce the expression of ISGs and HIF-1a, respectively. Interactions between HIF-1a and the ISG15 and ISGylation system were studied using knockdown of mRNA expression, immunoblotting, coimmunoprecipitation, and pull-down analyses. Effects of the ISG15 and ISGylation system on the HIF-1a-directed processes were examined using reporter, reverse transcription polymerase chain reaction (RT-PCR), and tumorigenic growth assays.Results: We found that the level of the free form of HIF-1a is differentially regulated by IFN treatment, and that the free ISG15 level is lower under hypoxia. Mechanism-directed studies have shown that HIF-1a not only interacts physically with ISG15, but is also ISGylated in multiple domains. ISG15 expression disrupts the functional dimerization of HIF-1a and -1b. Subsequently, expression of the ISG15 and/or ISGylation system attenuates HIF-1a-mediated gene expression and tumorigenic growth.Conclusion: In summary, our results revealed cross-talk between inflammatory and hypoxic pathways through the ISGylation of HIF-1a. On the basis of these results, we propose a novel negative feedback loop for the HIF-1a-mediated pathway involving the regulation of HIF-1a via IFN-induced ISGylation.