Factors Associated With an Intra-articular Infection After Anterior Cruciate Ligament Reconstruction: A Large Single-Institution Cohort Study.

BACKGROUND: An intra-articular infection after anterior cruciate ligament (ACL) reconstruction (ACLR) is a rare complication but one with potentially devastating consequences. The rare nature of this complication raises difficulties in detecting risk factors associated with it and with worse outcomes after one has occurred. PURPOSE: To (1) evaluate the association between an infection after ACLR and potential risk factors in a large single-center cohort of patients who had undergone ACLR and (2) assess the factors associated with ACL graft retention versus removal. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: All ACLR procedures performed at our institution between January 2010 and December 2018 were reviewed; a total of 11,451 procedures were identified. A retrospective medical record review was performed to determine the incidence of infections, patient and procedure characteristics associated with an infection, infection characteristics, incidence of ACL graft retention, and factors associated with the retention versus removal of an ACL graft. Multivariable logistic regression analysis was used to identify potential risk factors for an infection after ACLR. RESULTS: Of the 11,451 ACLR procedures, 48 infections were identified (0.42%). Multivariable logistic regression analysis revealed revision ACLR (odds ratio [OR], 3.13 [95% CI, 1.55-6.32]; P = .001) and younger age (OR, 1.06 [95% CI, 1.02-1.10]; P = .001) as risk factors for an infection. Compared with bone-patellar tendon-bone autografts, both hamstring tendon autografts (OR, 4.39 [95% CI, 2.15-8.96]; P < .001) and allografts (OR, 5.27 [95% CI, 1.81-15.35]; P = .002) were independently associated with an increased risk of infections. Overall, 15 ACL grafts were removed (31.3%). No statistically significant differences besides the number of irrigation and debridement procedures were found for retained versus removed grafts, although some trends were identified (P = .054). CONCLUSION: In a large single-center cohort of patients who had undergone ACLR and those with an infection after ACLR, patients with revision cases and younger patients were found to have a higher incidence of infection. The use of bone-patellar tendon-bone autografts was found to be associated with the lowest risk of infection after ACLR compared with both hamstring tendon autografts and allografts. Larger cohorts with a larger number of infection cases are needed to determine the factors associated with graft retention versus removal.

Sequencing of Circulating Microbial Cell-Free DNA Can Identify Pathogens in Periprosthetic Joint Infections.

BACKGROUND: Over 1 million Americans undergo joint replacement each year, and approximately 1 in 75 will incur a periprosthetic joint infection. Effective treatment necessitates pathogen identification, yet standard-of-care cultures fail to detect organisms in 10% to 20% of cases and require invasive sampling. We hypothesized that cell-free DNA (cfDNA) fragments from microorganisms in a periprosthetic joint infection can be found in the bloodstream and utilized to accurately identify pathogens via next-generation sequencing. METHODS: In this prospective observational study performed at a musculoskeletal specialty hospital in the U.S., we enrolled 53 adults with validated hip or knee periprosthetic joint infections. Participants had peripheral blood drawn immediately prior to surgical treatment. Microbial cfDNA from plasma was sequenced and aligned to a genome database with >1,000 microbial species. Intraoperative tissue and synovial fluid cultures were performed per the standard of care. The primary outcome was accuracy in organism identification with use of blood cfDNA sequencing, as measured by agreement with tissue-culture results. RESULTS: Intraoperative and preoperative joint cultures identified an organism in 46 (87%) of 53 patients. Microbial cfDNA sequencing identified the joint pathogen in 35 cases, including 4 of 7 culture-negative cases (57%). Thus, as an adjunct to cultures, cfDNA sequencing increased pathogen detection from 87% to 94%. The median time to species identification for cases with genus-only culture results was 3 days less than standard-of-care methods. Circulating cfDNA sequencing in 14 cases detected additional microorganisms not grown in cultures. At postoperative encounters, cfDNA sequencing demonstrated no detection or reduced levels of the infectious pathogen. CONCLUSIONS: Microbial cfDNA from pathogens causing local periprosthetic joint infections can be detected in peripheral blood. These circulating biomarkers can be sequenced from noninvasive venipuncture, providing a novel source for joint pathogen identification. Further development as an adjunct to tissue cultures holds promise to increase the number of cases with accurate pathogen identification and improve time-to-speciation. This test may also offer a novel method to monitor infection clearance during the treatment period. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Bacterial toxins in musculoskeletal infections.

Musculoskeletal infections (MSKIs) remain a major health burden in orthopaedics. Bacterial toxins are foundational to pathogenesis in MSKI, but poorly understood by the community of providers that care for patients with MSKI, inducing an international group of microbiologists, infectious diseases specialists, orthopaedic surgeons and biofilm scientists to review the literature in this field to identify key topics and compile the current knowledge on the role of toxins in MSKI, with the goal of illuminating potential impact on biofilm formation and dispersal as well as therapeutic strategies. The group concluded that further research is needed to maximize our understanding of the effect of toxins on MSKIs, including: (i) further research to identify the roles of bacterial toxins in MSKIs, (ii) establish the understanding of the importance of environmental and host factors and in vivo expression of toxins throughout the course of an infection, (iii) establish the principles of drug-ability of antitoxins as antimicrobial agents in MSKIs, (iv) have well-defined metrics of success for antitoxins as antiinfective drugs, (v) design a cocktail of antitoxins against specific pathogens to (a) inhibit biofilm formation and (b) inhibit toxin release. The applicability of antitoxins as potential antimicrobials in the era of rising antibiotic resistance could meet the needs of day-to-day clinicians.

Assessing the Role of Daptomycin as Antibiotic Therapy for Staphylococcal Prosthetic Joint Infection.

Background: The role of daptomycin, a potent, safe, convenient anti-staphylococcal antibiotic, in treatment of prosthetic joint infection (PJI) is unclear. We evaluated our experience with the largest cohort of patients with staphylococcal PJI managed with daptomycin. Methods: A cohort of staphylococcal hip and knee PJI treated with daptomycin was identified by hospital records from 2009 to 2016. All cases met Musculoskeletal Infection Society International Consensus criteria for PJI. The primary endpoint was 2 year prosthesis retention. Univariate analyses and regression statistics were calculated. Results: 341 patients with staphylococcal PJI were analyzed. 154 two-stages (77%) and 74 DAIR procedures (52%) met criteria for treatment success at 2 years. 77 patients were treated with daptomycin, of which 34 two-stages (68%) and 15 DAIRs (56%) achieved treatment success. Pairwise and regression analysis found no association between treatment success and daptomycin use. Organism (DAIR only) and Charlson Comorbidity Index scores (DAIR and two-stage) were significantly associated with treatment outcome. Six daptomycin patients (7.8%) had adverse side effects. Discussion: Daptomycin fared no better or worse than comparable antibiotics in a retrospective cohort of staphylococcal hip and knee PJI patients, regardless of surgical strategy. Conclusion: The convenient dosing, safety, and potency of daptomycin make it an attractive antibiotic for staphylococcal PJI. However, these advantages must be weighed against higher costs and rare, but serious side effects.

Musculoskeletal Infection Society (MSIS) Update on Infection in Arthroplasty.

Periprosthetic joint infection (PJI) continues to be a devastating problem in the field of total joint arthroplasty, and recent literature can be used to make the preoperative diagnosis of PJI, guide nonsurgical and surgical treatment, and provide postoperative antimicrobial management of PJI patients. The diagnosis of PJI relies on traditional serum and synovial fluid tests, with newer biomarkers and molecular tests. Surgical treatment depends on the duration of infection, host qualities, and surgeon factors, and procedures include débridement, antibiotics, and implant retention, one-stage exchange arthroplasty, two-stage exchange arthroplasty, resection arthroplasty, fusion, or amputation. Appropriate management of PJI involves coordination with infectious disease consultants, internal medicine physicians, and orthopaedic surgeons. Antimicrobial management is guided by the organisms involved, whether it is a new or persistent infection, and antibiotic suppression should be administered on an individual case basis. The goals of this instructional course lecture are to review the most relevant recent literature and provide treating physicians and surgeons with the most up-to-date armamentarium to reduce the recurrence of PJI.

Prophylactic Postoperative Antibiotics May Not Reduce Pin Site Infections After External Fixation.

BACKGROUND: Pin infection continues to be a nuisance when using definitive external fixation. Prophylactic antibiotic treatment has been proposed in an effort to decrease pin complications. QUESTIONS/PURPOSES: We performed a prospective, randomized, single-blinded study to answer the following questions: (1) what was the effect of a 10-day course of oral prophylactic antibiotics administered immediately after external fixation surgery on the incidence of a subsequent pin infection, (2) what was the effect on the severity of a subsequent pin infection, and (3) what was the effect on the timing of a subsequent pin infection? METHODS: Patients were randomized into antibiotic treatment and control groups, and incidence, severity, and time of onset of pin infection were recorded. RESULTS: The incidence of pin infection for the entire cohort during the 90-day observation period was 46/58 (79%) without a statistically significant difference (p = 0.106). There was no statistical difference found (p = 0.512) in pin infection severity. There was no significant difference in the time of onset of infection between the two groups from the date of surgery (p = 0.553). CONCLUSIONS: Our randomized data do not suggest that oral antibiotics alter the incidence, timing, or severity of pin infection. This study does not support the use of prophylactic oral antibiotics in healthy patients.

Globicatella sanguinis Osteomyelitis and Bacteremia: Review of an Emerging Human Pathogen with an Expanding Spectrum of Disease.

BACKGROUND: Globicatella sanguinis is an uncommon pathogen that may be misdiagnosed as viridans group streptococci. We review the literature of Globicatella and report 2 clinical cases in which catalase-negative Gram-positive cocci resembling viridans group streptococci with elevated minimum inhibitory concentrations (MICs) to ceftriaxone were inconsistently identified phenotypically, with further molecular characterization and ultimate identification of G sanguinis. METHODS: Two clinical strains (from 2 obese women; 1 with a prosthetic hip infection and the other with bacteremia) were analyzed with standard identification methods, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, 16S recombinant ribonucleic acid (rRNA), and sodA polymerase chain reaction (PCR). The existing medical literature on Globicatella also was reviewed. RESULTS: Standard phenotypic methods failed to consistently identify the isolates. 16S PCR yielded sequences that confirmed Globicatella species. sodA sequencing provided species-level identification of G sanguinis. The review of literature reveals G sanguinis as an increasingly reported cause of infections of the urine, meninges, and blood. To our knowledge, this is the first reported case of an orthopedic infection caused by Globicatella sanguinis. A review of the 37 known cases of G sanguinis infection revealed that 83% of patients are female, and 89% are at the extremes of age (<5 or >65 years). CONCLUSIONS: Globicatella sanguinis, an uncommon pathogen with elevated minimum inhibitory concentrations to third-generation cephalosporins, is difficult to identify by phenotypic methods and typically causes infections in females at the extremes of age. It may colonize skin or mucosal surfaces. Advanced molecular techniques utilizing 16S rRNA with sodA PCR accurately identify G sanguinis.

Fungal Musculoskeletal Infections.

Fungi are rare but important causes of osteoarticular infections, and can be caused by a wide array of yeasts and molds. Symptoms are often subacute and mimic those of other more common causes of osteoarticular infection, which can lead to substantial delays in treatment. A high index of suspicion is required to establish the diagnosis. The severity of infection depends on the inherent pathogenicity of the fungi, the immune status of the host, the anatomic location of the infection, and whether the infection involves a foreign body. Treatment often involves a combination of surgical debridement and prolonged antifungal therapy.

Prosthetic joint infections secondary to rapidly growing mycobacteria: Two case reports and a review of the literature.

Rapidly growing mycobacteria (RGM) are a rare but treatable cause of prosthetic joint infections. This study reports on two patients comprising three prosthetic joint infections caused by RGM successfully treated at the institution. With removal of the infected prosthetic joint and judicious use of prolonged courses of antibiotics, patients with prosthetic joint infections secondary to RGM can both be cured and retain function of the affected joint. In addition, this study identified 40 additional cases reported during an extensive review of the literature and provide a summary of these cases. These infections can present within days of arthroplasty or can develop only decades after the index surgery. The clinical presentations often mimic those of more routine bacterial prosthetic joint infections.

Successful treatment of Candida osteoarticular infections with limited duration of antifungal therapy and orthopedic surgical intervention.

BACKGROUND: Current guidelines for treatment of Candida osteoarticular infections (COAIs) recommend a prolonged course of antifungal therapy (AFT) of 6-12 months. Based upon strategies developed at the Hospital for Special Surgery (HSS), we hypothesized that the duration of antifungal therapy may be substantially reduced for management of COAI. METHODS: This was a retrospective chart review of cases of COAI treated at the HSS for the past 14 years. COAI was documented by open biopsy and direct culture in all cases. The mean (95% confidence interval, CI) duration of documented follow-up was 39 (16-61) months. RESULTS: Among the 23 cases of COAI, the median age was 62 years (range 22-83 years) with 61% having no underlying condition. Orthopedic appliances, including joint prostheses and fracture hardware, were present in 74% of cases. All patients had COAI as the first proven site of candidiasis. Candida albicans and Candida parapsilosis were the most common species. Hip, knee, foot, and ankle were the most common sites. All patients received aggressive surgical intervention followed by AFT administered for a mean (95% CI) duration of 45 (38-83) days. Systemic AFT consisted principally of fluconazole alone (65%) or in combination with other agents (26%). Adjunctive intraoperative amphotericin B irrigation was used in 35%. Among eight cases of CAOI that required placement of a new prosthetic joint, all were successfully treated. There were no microbiologic failures. CONCLUSIONS: Candida osteoarticular infections may be successfully treated with substantially limited durations of AFT when combined with a thorough surgical approach.

Perioperative infection in the patient with rheumatic disease.

The risk of infection accompanies the benefits of surgery. Immunomodulatory chronic illnesses may increase the risk of surgical infections. Surgical patients with rheumatologic illness need close preoperative assessment regarding their infection risks (fixed and modifiable), which vary on the basis of the proposed procedure, specific rheumatologic illness, and underlying comorbidities. Modification of the medication regimens in the preoperative period may decrease risk and enhance healing. Intraoperative antisepsis and antibiotic prophylaxis remain critical in this patient population. Postoperative fevers within 3 days of surgery are usually noninfectious but require vigilance and attention. The principles of surgical infection reduction are not different in the rheumatologic and general patient populations, but best practice depends on expertise in caring for patients with these illnesses.

Postoperative infections of the lumbar spine: presentation and management.

PURPOSE: Postoperative surgical site infections (SSI) are a frequent complication following posterior lumbar spinal surgery. In this manuscript we review strategies for prevention, diagnosis and treatment of SSI. METHODS: The literature was reviewed using the Pubmed database. RESULTS: We identified fifty-nine relevant manuscripts almost exclusively composed of Level III and IV studies. CONCLUSIONS: Risk factors for SSI include: 1) factors related to the nature of the spinal pathology and the surgical procedure and 2) factors related to the systemic health of the patient. Staphylococcus aureus is the most common infectious organism in reported series. Proven methods to prevent SSI include prophylactic antibiotics, meticulous adherence to aseptic technique and frequent release of retractors to prevent myonecrosis. The presentation of SSI is varied depending on the virulence of the infectious organism. Frequently, increasing pain is the only presenting complaint and can lead to a delay in diagnosis. Magnetic resonance imaging and the use of C-reactive protein laboratory studies are useful to establish the diagnosis. Treatment of SSI is centered on surgical debridement of all necrotic tissue and obtaining intra-operative cultures to guide antibiotic therapy. We recommend the involvement of an infectious disease specialist and use of minimum serial bactericidal titers to monitor the efficacy of antibiotic treatment. In the most cases, SSI can be adequately treated while leaving spinal instrumentation in place. For severe SSI, repeat debridement, delayed closure and involvement of a plastic surgeon may be necessary.

Historical perspective on two-stage reimplantation for infection after total hip arthroplasty at Hospital for Special Surgery, New York City.

In this article, we report on our use of a 2-stage exchange in managing infected total hip arthroplasties (THAs) at the Hospital for Special Surgery in New York City. This protocol involves resection arthroplasty, 6 weeks of intravenous antibiotics to obtain a minimum "postpeak" serum bactericidal titer (SBT) of 1:8, and reimplantation. Over the past 20 years, we have conducted several studies showing the effectiveness of this treatment. Since our previous report was published in 1994, prevalence of multidrug-resistant (MDR) organisms has increased significantly. In 2008, we set out to determine if 2-stage exchange remains an effective treatment for newer pathogens, many of which are MDR. The overall eradication rate was 95% (80/84 hips). All 21 MDR pathogens implicated in the infected THAs were eradicated. We conclude that 2-stage exchange with a standard 1:8 minimum SBT remains an effective treatment even when resistant infections are involved.

Modern treatment of infected total knee arthroplasty with a 2-stage reimplantation protocol.

The purpose of this study was to determine if 2-stage reimplantation for the treatment of infected total knee arthroplasty (TKA) is still effective for treating contemporary pathogens, many of which are multidrug resistant (MDR). The medical records of all cases of infected TKAs from April 1998 to March 2006 were retrospectively reviewed for data on infecting organism and success of treatment. Of 72 patients (75 knees), with a minimum of 2 years of follow-up, who completed the protocol, the infection was eradicated in 90.7% (68/75 knees). Thirty-one (91.2%) of 34 of MDR infections and 42 (91.3%) of 46 of non-MDR infections were successfully treated. These results support previous studies that demonstrated the effectiveness of a 2-stage reimplantation protocol with a standard 1:8 minimal bactericidal titer for treating infections after TKA, including MDR organisms.

Propionibacterium acnes infection after shoulder arthroplasty: a diagnostic challenge.

HYPOTHESIS: This study reviewed a series of patients diagnosed with Propionibacterium acnes infection after shoulder arthroplasty in order to describe its clinical presentation, the means of diagnosis, and provide options for treatment. MATERIALS AND METHODS: From 2002 to 2006, 11 patients diagnosed with P acnes infection after shoulder arthroplasty were retrospectively reviewed and analyzed for (1) clinical diagnosis; (2) laboratory data, including white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP); (3) fever; (4) number of days for laboratory growth of P acnes; (5) organism sensitivities; (6) antibiotic regimen and length of treatment; and (7) surgical management. Infection was diagnosed by 2 positive cultures. RESULTS: Five patients had an initial diagnosis of infection and underwent implant removal, placement of an antibiotic spacer, and staged reimplantation after a course of intravenous antibiotics. In the remaining 6 patients, surgical treatment varied according to the clinical diagnosis. When infection was recognized by intraoperative cultures, antibiotics were initiated. The average initial ESR and CRP values were 33 mm/h and 2 mg/dL, respectively. The average number of days from collection to a positive culture was 9. All cultures were sensitive to penicillin and clindamycin and universally resistant to metronidazole. DISCUSSION: Prosthetic joint infection secondary to P acnes is relatively rare; yet, when present, is an important cause of clinical implant failure. Successful treatment is hampered because clinical findings may be subtle, many of the traditional signs of infection are not present, and cultures may not be positive for as long as 2 weeks.

Dental premedication protocols for patients with knee and hip protheses.

In 1997, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) published an advisory statement regarding antibiotic prophylaxis for patients with total joint replacements undergoing dental treatment. The first periodic update of these guidelines was published in 2003. Nevertheless, confusion exists among dentists and physicians as to the clinical indications for premedication in this patient population. This article serves as an overview of current recommendations for use of chemoprophylaxis in the dental treatment of patients ith prosthetic joints.