Xavier Flores

Antibiotic Susceptibility in Gram-Positive Chronic Joint Arthroplasty Infections: Increased Aminoglycoside Resistance Rate in Patients With Prior Aminoglycoside-Impregnated Cement Spacer Use

Two-stage revision using aminoglycoside-cement spacers (A-CSs) is widely used to manage chronic periprosthetic joint infection (PJI). However, aminoglycoside-resistance in gram-positive cocci (GPC) seems to be increasing. Moreover, the contribution of these A-CSs to select resistant mutants is a matter of concern. We study the antibiotic susceptibility profile of GPC after 113 chronic hip and knee PJIs. Aminoglycoside susceptibility-profiles were compared between cases where A-CSs had previously been used (n: 52), and cases of primary infection (n: 61). 32% of isolates were resistant to gentamicin and 40.6% to tobramycin. Gentamicin resistance after previous A-CS use was significantly higher (49.2% [30/61] vs. 19.3% [16/83]; P: 0.0001) as well as with tobramycin (52.7% [29/55] vs. 30.9% [21/66]; P: 0.014). A high rate of gentamicin-tobramycin resistance exists among the most common bacteria involved in chronic-PJI. The risk of selection for aminoglycoside-resistant mutants in cases of infection relapse is a concern following A-CS use.

Percutaneous interface biopsy in dry-aspiration cases of chronic periprosthetic joint infections: A technique for preoperative isolation of the infecting organism

PurposePreoperative identification of the infecting micro-organism is of paramount importance in the treatment protocol for chronic periprosthetic joint infections, as it enables selection of the most appropriate antibiotic treatment. Preoperative joint aspiration, the most commonly used sampling technique, has proven to have a broad range of sensitivity values and the frequency of dry aspirations has not been well assessed. In such dry-tap cases a biopsy sample could be an option. The purpose of this study was to assess the diagnostic accuracy of percutaneous interface biopsy (PIB) in isolating the infecting organism in cases of chronic Periprosthetic Joint Infection (PJI) and dry-tap event. The basic technique is to harvest and culture a sample from the periprosthetic interface membrane by a percutaneous technique in the preoperative period.MethodsA retrospective study was done involving 24 consecutive patients suspected of PJI and where no fluid was obtained from the joint. Culture results from a percutaneous interface biopsy (PIB) were compared with intraoperative tissue cultures at the time of revision surgery. In all cases, a two-stage replacement was done.ResultsThe sensitivity was 88.2%; specificity was 100%. Positive predictive value was 100%, while negative predictive value was 77.9%. Accuracy was 91.6%. No technique-related complication was observed.ConclusionWe conclude that PIB is a useful test for preoperative isolation of the infecting organism and could play a role in cases with dry-tap joint aspirations.

Industrially Prefabricated Cement Spacers: Do Vancomycin- and Gentamicin-impregnated Spacers Offer Any Advantage?

BackgroundIndustrially preformed antibiotic-loaded cement spacers are useful to facilitate the second stage of two-stage exchange arthroplasty for infected THAs and TKAs. However, whether gentamicin alone or a combination of antibiotics (such as vancomycin and gentamicin) is more effective is not known.Questions/purposesWe therefore sought to compare industrially prefabricated spacers containing either gentamicin or gentamicin and vancomycin with respect to (1) infection control, (2) complications, and (3) quality of life, pain, and patient satisfaction.MethodsWe performed a review of 51 patients with chronic infections treated at one center using either gentamicin or vancomycin and gentamicin-prefabricated spacers. The former were used exclusively from January 2006 until May 2009, and the latter from June 2009 until July 2011, and there was no overlap. We collected data on demographics, immunologic status (McPherson classification), prosthetic joint infection location, type of prosthesis, microbiologic results, and time between stages. We evaluated the primary outcome of infection control or recurrence after at least 12 months followup. We also recorded complications. Each patient completed a quality-of-life survey, VAS, and a self-administered satisfaction scale.ResultsThe overall infection control rate was 83% after a mean followup of 35 months (range, 12.4–64.7 months). There were no differences between gentamicin and vancomycin and gentamicin spacers in terms of infection eradication (80 % versus 85 %, respectively; p = 0.73), nor in terms of complications, quality of life, pain, or satisfaction scores.ConclusionsPrefabricated, antibiotic-loaded cement spacers has been proven effective for infection control in TKAs and THAs but with the numbers available, we did not find any differences between a gentamicin or vancomycin and gentamicin-prefabricated spacer, and therefore, we are unable to validate the superiority of the combination of vancomycin and gentamicin over gentamicin alone. Because of the higher costs involved with vancomycin and gentamicin spacers, and the potential risks of unselective use of vancomycin, further comparative studies are necessary to evaluate their role in the treatment of infected THAs or TKAs.Level of EvidenceLevel III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Outcome after Knee Arthrodesis for Failed Septic Total Knee Replacement Using a Monolateral External Fixator

Purpose. To evaluate the pain level and patient satisfaction as well as the fusion and infection eradication rates after knee arthrodesis using a monolateral external fixator for failed septic total knee replacement (TKR). Methods. Records of 10 male and 11 female consecutive patients aged 70 to 88 (mean, 81) years who underwent knee arthrodesis using a monolateral external fixator for failed septic TKR were retrospectively reviewed. Each patient had undergone a mean of 3.4 (range, 1–15) procedures. The infection eradication rate, fusion rate, time to achieve fusion, pain level, patient satisfaction, and health-related quality of life were evaluated. Results. Infection was eradicated in 18 (86%) of the 21 patients, whereas fusion was achieved in 17 (81%) of the 21 patients after a mean of 10.3 (range, 4–16) months. Those who did and did not achieve fusion differed significantly in terms of the mean pain score (2.3 vs. 6.4, p=0.031). Compared with age-matched Spanish general population, patients aged >75 years fared significantly worse in terms of the mean physical summary component score (40.7 vs. 34.9, p=0.001). Among those who achieved fusion, 82% were very or somewhat satisfied; none was very dissatisfied. Among those who did not achieve fusion, 75% were very or somewhat dissatisfied. Conclusion. Knee arthrodesis using a monolateral external fixator for failed septic TKR achieved high fusion and infection eradication rates, despite the extended time needed. When fusion is achieved, patients had good pain relief and satisfaction.

Case report: first report of a prosthetic joint infection caused by Facklamia hominis☆ , ☆☆ ,★

Facklamia spp. are gram-positive cocci first described in 1997. They are α-hemolytic, facultative anaerobes, catalase-negative cocci, resembling viridians streptococci on 5% sheep blood agar. Facklamia hominis is, by far, the most common species of the 6 so far described, and it is thought that its natural habitat is the female genital tract. Four previous human infections with Facklamia spp. have been documented. We report the first case of a chronic prosthetic joint infection caused by F. hominis and its successful treatment by a 2-stage exchange procedure to eradicate the infection. This is also the first osteoarticular infection reported. The clinical implications are discussed.

Two-stage knee arthrodesis using a cemented modular tumour replacement system for recalcitrant septic proximal tibial non-union: a case report

Knee arthrodesis is an alternative to amputation for treating recalcitrant septic non-union of the proximal tibia with bone loss, soft-tissue compromise, and knee-joint involvement. Nonetheless, arthrodesis is difficult to achieve if bone loss is massive, and the septic environment can result in failed bone fusion. We report on a 77-year-old man with massive bone loss secondary to recalcitrant septic non-union who underwent radical bone resection, followed by knee arthrodesis using a cemented modular intercalary megaprosthesis in conjunction with a microvascularised flap in 2 stages.