Risk Factors for Fungal Prosthetic Joint Infection.

Background: Fungal prosthetic joint infections (PJIs) are rare and often associated with poor outcome; however, risk factors are not well described. Methods: This was a retrospective case control study among all patients with PJIs from 2006-2016 at two major academic centers. Each fungal PJI case was matched 1:1 with a bacterial PJI control by joint (hip, knee, shoulder) and year of diagnosis. We compared demographics, comorbidities, and clinical characteristics between cases and controls using chi square/Fisher's exact or Wilcoxon rank sum test. Independent risk factors were identified with multivariable logistic regression. Results: Forty-one fungal PJIs occurred over the study and 61% were due to Candida albicans. The hip was involved in 51.2% of cases, followed by the knee (46.3%). Compared to bacterial PJI, fungal PJI cases were more likely to have received antibiotics within the previous 3 months (70.7% vs 34%, P=.001), wound drainage lasting >5 days (48% vs 9%, P=.0002), had a lower median CRP (2.95 mg/dl vs 5.99, P=.013) and synovial fluid white blood cell count (13,953 cells/mm3 vs 33,198, P=.007), and a higher proportion of prior two-stage exchanges (82.9% vs 53.6%, P=.008). After controlling for center, prolonged wound drainage (OR, 7.3; 95% CI, 2.02-26.95) and recent antibiotics (OR, 3.4; 95% CI, 1.2-9.3) were significantly associated with fungal PJI. Conclusion: In our study, Candida albicans was the most common species in fungal PJIs and prolonged wound drainage and recent antibiotics were independent risk factors. These clinical characteristics may help providers anticipate fungal PJI and adjust management strategies.

Cutibacterium acnes Infection in Orthopedics: Microbiology, Clinical Findings, Diagnostic Strategies, and Management.

Cutibacterium (formerly called Propionibacterium) acnes is a human skin flora often implicated in orthopedic infections. The unique characteristics of this microorganism make the diagnosis of infection difficult. The diagnosis often is made based on clinical evidence, radiographic signs, and laboratory and/or surgical findings combined. Treatment often involves both pharmacologic and surgical methods. In addition, formation of biofilms and increased resistance to drugs exhibited by the microorganism can require combined antimicrobial therapy. Prophylactic measures are particularly important, but no single method has been shown to fully eliminate the risk of C acnes infections. Previous reports have focused on C acnes infections involving surgical implants or after certain orthopedic procedures, particularly in the shoulder and spine. This article reviews current clinical, diagnostic, and treatment principles for C acnes in orthopedics in general. [Orthopedics. 2020; 43(1):52-61.].

Peripherally inserted central catheter-associated bloodstream infection: Risk factors and the role of antibiotic-impregnated catheters for prevention.

BACKGROUND: Antimicrobial-impregnated (AIP) peripherally inserted central catheters (PICCs) may lower risk of central line-associated bloodstream infection (CLABSI) compared with nonantimicrobial-impregnated (NAIP) catheters. We sought to assess risk factors for CLABSI with a focus on the effect of AIP PICCs. METHODS: CLABSI rate was determined among patients who received PICCs from July 2009 through June 2012 using a retrospective study design. A nested case-control study matched for operators (interventional radiology [IR], infectious diseases [IDs], and the nurse venous access team [VAT]) was conducted to assess risks for PICC CLABSI. RESULTS: Eighty-nine PICC CLABSIs (1.66%) occurred among 5,372 PICC placements a mean of 32 days after placement. Higher infection risk (1.75) was observed for IR-placed PICCs compared with ID-placed PICCs (P = .02). In addition, higher infection risk (4.22) was observed for IR-placed PICCS compared with VAT-placed PICCs (P = .0008). IR-placed NAIP catheters, as indicated by multivariate analysis, revealed a 5.45-fold greater CLABSI risk compared with AIP catheters (P < .0005). Other risk factors included chemotherapy, placement of a tunneled catheter, leukemia, and AIDS. CONCLUSIONS: PICC CLABSIs were highest among patients receiving NAIP catheters in this large study. Highest risk occurred with placement of a tunneled catheter, AIDS, leukemia, and if the indication for PICC was chemotherapy. Our study suggests that the AIP PICC should be considered in all patients receiving PICCs.

Outcome of enterococcal prosthetic joint infection: is combination systemic therapy superior to monotherapy?

BACKGROUND: The optimal medical or surgical therapy and outcome of enterococcal prosthetic joint infection are unknown. METHOD: We performed a retrospective cohort study involving all patients with enterococcal total hip or knee arthroplasty infection treated at our institution from 1969 through 1999. The outcome for patients treated with combination systemic antimicrobial therapy (a cell wall-active agent and an aminoglycoside) versus monotherapy with a cell wall-active agent was analyzed. RESULTS: Fifty episodes of prosthetic joint infection due to enterococci occurred in 47 patients. The median duration of follow-up was 1253 days (range, 29-4610 days). The median age at the time of diagnosis was 70 years (range, 32-89 years). Fifty percent of episodes (25 of 50 episodes) occurred in male patients; 48% (24 of 50 episodes) involved total hip or knee arthroplasty. The estimate of 2-year survival free of treatment failure was 94% (95% confidence interval [CI], 83%-100%) for patients treated with 2-stage exchange, 76% (95% CI, 58%-100%) for patients treated with resection arthroplasty, and 80% (95% CI, 51.6%-100%) for patients treated with debridement and retention of the components (P=.9). The overall rate of 2-year survival free of treatment failure was 88% (95% CI, 77%-100%) for patients treated with monotherapy and 72% (95% CI, 54%-96%) for patients treated with combination therapy (P=.1). The development of cranial nerve VIII toxicity was significantly more common among patients receiving combination therapy (P=.002). Nephrotoxicity was more frequent in the combination therapy group (occurring in 26% of episodes; P=.09). CONCLUSIONS: Enterococcal prosthetic joint infection is uncommon at our institution. Patients receiving combination therapy and those receiving monotherapy did not differ with respect to outcome. There were more cases of ototoxicity in the combination therapy group than there were in the monotherapy group.

Polymicrobial prosthetic joint infections: risk factors and outcome.

UNLABELLED: Limited data are available regarding the risk factors and outcome of polymicrobial prosthetic joint infection (PJIs) when compared with monomicrobial PJI. Between January 1998 and November 2006, we retrospectively identified 34 of 174 prosthetic joint infections (19%) were polymicrobial. The 2-year cumulative probability of success of treating polymicrobial and monomicrobial PJIs was 63.8% and 72.8%, respectively. Twenty-six percent, 38%, and 29% of PJIs were treated with two-stage exchange, débridement and retention, or resection arthroplasty, respectively, and the 2-year survival rate free of treatment failure in each group was 77.7% (95% confidence interval, 42.8%-94.2%), 52.7% (95% confidence interval, 28.4%-75.9%), and 64.2% (95% confidence interval, 28.7%-88.9%). Methicillin-resistant Staphylococcus aureus (26.4% versus 7.1%) and anaerobes (11.7% versus 2.8%) were more common in polymicrobial PJIs. Polymicrobial PJIs occurred in patients with a soft tissue defect/dehiscence (23.5% versus 2.8%), drainage (79.4% versus 39.2%), or prior local irradiation (8.8% versus 0.71%). We found the following factors associated with polymicrobial prosthetic joint infections: the presence of a soft tissue defect/wound dehiscence (odds ratio, 5.9), drainage (odds ratio, 5.0), and age 65 years or older (odds ratio, 2.8). LEVEL OF EVIDENCE: Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

A Case of Malaria Predisposing to Salmonella Bacteremia in a Returning Traveler from Nigeria.

We describe a febrile adult returning to the U.S. from Nigeria. Malaria was diagnosed by rapid antigen testing, but recognition of invasive nontyphoidal Salmonella disease was delayed. While the moniker, "typhomalaria," once used to describe an illness with features of malaria and typhoid fever, has fallen out of favor, it may nevertheless be a helpful reminder to clinicians that both infectious diseases can arise in the same patient. Blood cultures should be obtained routinely in febrile returning travelers from malaria-endemic regions, including those in whom the diagnosis of malaria has already been established.

Culture-negative prosthetic joint infection.

BACKGROUND: Culture-negative (CN) prosthetic joint infection (PJI) has not been well studied. We performed a retrospective cohort study to define the demographic characteristics and determine the outcome of patients with CN PJI. METHODS: All cases of CN total hip arthroplasty and total knee arthroplasty infections (using a strict case definition) treated at our institution from January 1990 through December 1999 were analyzed. Kaplan-Meier survival methods were used to determine the cumulative probability of success. RESULTS: Of 897 episodes of PJI during the study period, 60 (7%) occurred in patients for whom this was the initial episode of CN PJI. The median age of the cohort was 69 years (range, 36-87 years). Patients had received a prior course of antimicrobial therapy in 32 (53%) of 60 episodes. Of the 60 episodes, 34 (57%), 12 (20%), and 8 (13%) were treated with 2-stage exchange, debridement and retention, and permanent resection arthroplasty, respectively. The median duration of parenteral antimicrobial therapy was 28 days (range, 0-88 days). Forty-nine (82%) of 60 episodes were treated with a cephalosporin. The 5-year estimate of survival free of treatment failure was 94% (95% confidence interval, 85%-100%) for patients treated with 2-stage exchange and 71% (95% confidence interval, 44%-100%) for patients treated with debridement and retention. CONCLUSIONS: CN PJI occurs infrequently at our institution. Prior use of antimicrobial therapy is common among patients with CN PJI. CN PJI treated at our institution is associated with a rate of favorable outcome that is comparable to that associated with PJI due to known bacterial pathogens.

Two-stage reimplantation for periprosthetic knee infection involving resistant organisms.

BACKGROUND: Two-stage reimplantation is the most accepted mode of treatment for patients with a periprosthetic infection following total knee arthroplasty. Most studies, however, do not stratify their results on the basis of the type of infecting organism. The purpose of this study was to determine the outcomes for patients who had two-stage reimplantation for the treatment of infection with a resistant organism, methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis, at the site of a total knee replacement. METHODS: A multicenter study was performed to review the cases of all patients treated between 1987 and 2003 because of an infection with methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis organisms at the site of a total knee replacement. The prevalence of reinfection following two-stage reimplantation was determined. Variables that may influence the outcome, such as the duration and type of intravenous antibiotics administered, previous surgery, and comorbidities of the host, were analyzed. RESULTS: We identified thirty-seven patients who had an infection with a resistant organism. All patients had negative cultures at the time of reimplantation. Four of the thirty-seven patients had a reinfection with the same organism, while five had a reinfection with a different organism. None of the variables noted above were found to be significantly associated with reinfection, on the basis of the numbers available. CONCLUSIONS: Reports in the literature have discouraged reimplantation for the treatment of an infection with a resistant organism at the site of a total knee replacement. While 24% of the patients in this series had a reinfection, 14% had a reinfection with a different organism. We believe that two-stage reimplantation remains a viable treatment option for patients who have an infection with a resistant organism at the site of a total knee replacement. LEVEL OF EVIDENCE: Therapeutic Level IV.

Prevention of Infection in Orthopedic Prosthetic Surgery.

Total joint arthroplasty is a generally safe orthopedic procedure; however, infection is a potentially devastating complication. Multiple risk factors have been identified for development of prosthetic joint infections. Identification of patients at risk and preoperative correction of known risk factors, such as smoking, diabetes mellitus, anemia, malnutrition, and decolonization of Staphylococcus carriers, represent well-established actions to decrease the infection risk. Careful operative technique, proper draping and skin preparation, and appropriate selection and dosing of antimicrobials for perioperative prophylaxis are also very important in prevention of infection.

Prevention of Surgical Site Infections in Joint Replacement Surgery.

Prosthetic joint infections (PJI), although rare, represent a serious complication of total joint arthroplasty as they pose not only a direct financial burden to the patient but also an indirect burden related to psychosocial impact that PJI incur on the patient. Treatment of PJI is complex and requires a combined surgical and medical approach. Patients are often subjected to multiple surgical procedures and prolonged courses of antimicrobial therapy. Therefore, all efforts should be directed toward maximizing the prophylactic measures in the peri-operative and post-operative phases in order to prevent the occurrence of surgical site infections. This article explores primarily the prophylactic measures that target the host and the operative theater environment. Implementation of such preventive measures requires a multi-disciplinary approach and is crucial for a successful outcome of the total joint arthroplasty.

Antibiotic prophylaxis in orthopedic prosthetic surgery.

The problem of prophylaxis in orthopedic implant surgery will become increasingly important and complex as the population ages and requires more arthroplasty procedures, and the prevalence of antimicrobial-resistant bacteria meanwhile also continues to rise. Energy spent preventing prosthetic joint infection is more effective than that expended in treating the infection of a prosthetic joint, once established. Preventive measures encompass a wide array of variables related to host response, wound environment, and microorganisms. Prophylaxis should address these areas in the preoperative, intraoperative, and postoperative periods. Antimicrobial prophylaxis remains the single most effective method of reducing the prevalence of infection after total joint arthroplasty. In the postoperative period, prophylaxis aims to protect the prosthetic joint against hematogenous seeding from oral, urologic, skin, or gastrointestinal sources. Currently, dental and urologic advisory statements provide recommendations for antimicrobial prophylaxis for high-risk patients with total joint arthroplasty undergoing high-risk procedures. Close collaboration between the orthopedic surgeon, urologist, or dentist and the infectious disease specialist is crucial for providing recommendations regarding prophylaxis in special circumstances. In these particular circumstances, individual decisions should be made based on clinical judgment.

Practical considerations in the use of outpatient antimicrobial therapy for musculoskeletal infections.

Successful treatment of many musculoskeletal infections often requires an extended course of outpatient antimicrobial therapy, much of which is administered parenterally outside the hospital under the guidance of an infectious disease specialist. Delivery of outpatient parenteral antimicrobial therapy (OPAT) may occur in physicians' offices, ambulatory infusion centers, or hospital clinics but most frequently is done in patients' homes, often by the patients themselves. In this article, we outline the essential elements of outpatient antimicrobial therapy for musculoskeletal infections with particular emphasis on OPAT, including patient selection and evaluation; antimicrobial administration, including the route, duration, and complications of central venous access; and clinical and laboratory monitoring of antimicrobial therapy. We believe that primary care physicians, orthopedists, and infectious disease specialists caring for patients with musculoskeletal infections should become familiar with the use of, indications for, and complications of OPAT.

Higher risk of failure of methicillin-resistant Staphylococcus aureus prosthetic joint infections.

We determined the effect of methicillin resistance on the outcome of patients with Staphylococcus aureus prosthetic joint infections. From January 1995 to December 2004, 33% of 137 episodes of prosthetic joint infections were the result of S. aureus (in monomicrobial or polymicrobial cultures). Thirty-three (24%) episodes among 31 patients were the result of methicillin-susceptible S. aureus and 12 (9%) episodes among 12 patients were the result of methicillin-resistant S. aureus. Overall treatment failure rate was 38%. Patients with methicillin-susceptible S. aureus or methicillin-resistant S. aureus prosthetic joint infections did not differ in age, gender, comorbidities, joint age, prior surgical procedures performed on the affected joint, number of postsurgical medical complications, or duration of intravenous antimicrobial therapy. Patients with methicillin-resistant S. aureus prosthetic joint infection had longer hospital durations (median, 15 versus 10 days). Methicillin-resistant S. aureus in periprosthetic tissue culture resulted in a higher risk of treatment failure (hazard ratio, 9.2; 95% confidence interval, 2.40-35.46) than methicillin-susceptible S. aureus when controlling for joint location (total knee arthroplasty versus total hip arthroplasty [hazard ratio, 5.8; 95% confidence interval, 1.52-22.19]) and removal of hardware (hazard ratio, 0.24; 95% confidence interval, 0.077-0.75). Efforts should be made to prevent methicillin-resistant S. aureus infections of joint arthroplasties and develop new treatment modalities.

Unusual aerobic and anaerobic bacteria associated with prosthetic joint infections.

The association of certain microorganisms, such as Staphylococcus epidermidis, Staphylococcus aureus, and beta-hemolytic streptococci, with prosthetic joint infection (PJI) has been recognized for many years. To our knowledge, a systematic review of the presentation and management of less commonly encountered species of coagulase-negative staphylococci, nutritional-variant streptococci, aerobic non-spore and spore forming Gram-positive or anaerobic bacteria is not available. We therefore sought to provide a comprehensive literature review of PJI due to these microorganisms that will provide a valuable and quick reference for clinicians caring for these patients. We conducted a Medline search of all case reports and case series of PJI due to unusual aerobic and anaerobic bacteria. The presentation, surgical, and medical management strategies were reviewed. Appropriate medical and surgical management of such infections is complex and evolving as newer diagnostic tests, surgical techniques and antimicrobials become available. Management of patients with these infections requires close collaboration between the orthopaedic surgeon, infectious disease specialist and microbiology laboratory.