The Use of Erythromycin and Colistin Cement in Total Knee Arthroplasty Does Not Reduce the Incidence of Infection: A Randomized Study in 2,893 Knees with a 9-year Average Follow-up.

AIM: One of the most severe complications of primary total knee arthroplasty (TKA) is prosthetic joint infection (PJI). Currently, the use of antibiotic-loaded cement for the prevention of infection is still controversial. The aim of the present study was to evaluate if the use of antibiotic-loaded cement reduces the infection rate in primary total knee arthroplasty in long-term follow-up (more than five years average follow up). METHOD: This study is the follow-up extension of a prospective randomized study, with 2,893 cemented TKA performed between 2005 and 2010 at our institution. There were two different cohorts depending on which bone cement was used: without antibiotics (control group) or those loaded with erythromycin and colistin (study group). All patients received the same systemic prophylactic antibiotics. The patients were followed for a minimum of twelve months. The diagnosis of PJI was done according to Zimmerli criteria. RESULTS: In 1,452 patients, the prosthetic components were fixed using bone cement without antibiotics, whereas in 1,441 patients, bone cement was loaded with erythromycin and colistin. Both groups were comparable in terms of all the possible risk factors studied. We found a total of 53 deep infections, with a mean rate of 1.8%. There were no differences between the groups as to whether bone cement with or without antibiotics had been used (P = 0.58). The average duration of follow-up was 8.7 years. In terms of prosthetic revision due to aseptic loosening, there were no differences between groups (P = 0.32), with 33 revision arthroplasties in the control group and 37 in the study group. Moreover, we analyzed the erythromycin resistance rate, with no differences between both groups (P = 0.6). CONCLUSIONS: The use of erythromycin and colistin-loaded bone cement in total knee arthroplasty did not lead to a decrease in the rate of infection in long-term follow-up, a finding that suggests that its use would not be indicated in the general population.

Acute Hematogenous Periprosthetic Hip Infection by Gemella morbillorum, Successfully Treated with Debridement, Antibiotics and Implant Retention: A Case Report and Literature Review of Osteoarticular Gemella morbillorum Infections.

Gemella morbillorum is a facultative anaerobic, catalase-negative and non-spore forming Gram-positive cocci. It can be found as part of the normal oropharyngeal flora, in the gastrointestinal tract and the female genital tract. However, it can be a causal agent of infections such as endocarditis, meningitis or brain abscesses, and very rarely can cause osteoarticular infections. Herein, a case report of an acute hematogenous prosthetic hip infection caused by Gemella morbillorum, successfully treated with a DAIR and beta-lactam antibiotic therapy, is presented. We provide a literature review of the other orthopedic-related infections caused by this microorganism.

Adherence to a reliable PJI diagnostic protocol minimizes unsuspected positive cultures rate.

BACKGROUND: The aim of the present study was to evaluate the incidence of unsuspected PJI when prosthetic revisions are thoroughly evaluated by PJI dedicated orthopedic surgeon before surgery. The hypothesis is that the incidence of unsuspected PJI is reduced by applying this protocol. METHODS: This is a historical cohort study carried out in one university hospital. The prosthetic revision assessment was carried out in January 2019. From that date on, all patients that were programmed for hip or knee revision (either by an orthopedic surgeon specialized or not in septic revisions) were scheduled for a preoperative visit with the same orthopedic surgeon specialized in septic revisions. The diagnostic algorithm applied was based on the Pro-Implant Foundation diagnostic criteria. Prior to the revision assessment, the indication for joint aspiration was done at the surgeons' discretion (non-specialized in septic revisions) and the preoperative identification of PJI was also done by a hip or knee surgeon (not specialized in septic surgery). RESULTS: Based on the PIF criteria, there were 15 infections among the revisions in group 1 and 18 PJI in group 2 (p > 0.05). The most interesting finding was that there were 7 patients with unsuspected positive cultures in group 1. That represents 11% of all revisions. No patient in group 2 was found with unsuspected positive cultures (p < 0.001). CONCLUSION: A thorough PJI diagnostic algorithm should be implemented before prosthetic revision to avoid unsuspected positive cultures.

C-reactive protein may misdiagnose prosthetic joint infections, particularly chronic and low-grade infections.

BACKGROUND: Periprosthetic tissue cultures, sonication and synovial fluid cultures remain the gold standard for prosthetic joint infection (PJI) diagnosis. However, some 15-20% culture-negative PJI are still reported. Therefore, there is the need for other diagnostic criteria. One point of concern relative to the different definitions of PJI is as to the inclusion of the c-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) as diagnostic criteria for PJI despite them being non-specific inflammatory blood tests. PURPOSE: The purpose of the present study was to determine the relevance of CRP and the ESR in the diagnosis of PJI. METHODS: All PJI with positive cultures over a two-year period in two hospitals were reviewed. The main variables of the present study were the type of prosthesis and the CRP level. More information was recorded in those patients with normal CRP: radiographs, physical examination records and the ESR. RESULTS: Seventy-three patients were included in study. Pre-operative CRP levels were normal (lower than 0.8 mg/dl) in 23 patients, representing 32% of all PJI with positive cultures. Low virulence micro-organisms, 12 coagulase-negative staphylococci and four P. acnes, grew in most of them. They represented 70% of all PJI with normal CRP levels. In addition, 17 patients (23% of all PJI with positive cultures) had a normal ESR, a normal physical examination (they only presented with pain) and no clear loosening was observed in the radiographs. CONCLUSIONS: Per the American Association of Orthopaedic Surgeons (AAOS) guidelines or the Musculoskeletal Infection Society (MSIS), 23% of the patients in the present study with PJI would never have been identified. Blood inflammatory markers such as the CRP level and ESR may not be accurate as diagnostic tools in PJI, particularly to identify low-grade and chronic PJI.

Improved diagnosis of orthopedic implant-associated infection by inoculation of sonication fluid into blood culture bottles.

Sonication improved the diagnosis of orthopedic implant-associated infections (OIAI). We investigated the diagnostic performance of sonication fluid inoculated into blood culture bottles in comparison with that of intraoperative tissue and sonication fluid cultures. Consecutive patients with removed orthopedic hardware were prospectively included and classified as having OIAI or aseptic failure (AF) according to standardized criteria. The diagnostic procedure included the collection of five intraoperative tissue cultures and sonication of the removed device, followed by conventional culture of the sonication fluid. Cultures were incubated for 7 days (aerobic) or 14 days (anaerobic). In addition, 10 ml of sonication fluid was inoculated into each aerobic and anaerobic BacT/Alert FAN blood culture bottle and incubated in the automated blood culture system for 5 days. Of 75 included patients, 39 had OIAI and 36 AF. The sensitivity of sonication fluid inoculated into blood culture bottles (100%) was higher than that of conventional sonication fluid (87%; P = 0.05) or intraoperative tissue cultures (59%; P < 0.01). Previous antibiotic therapy reduced the culture sensitivity of conventional sonication fluid to 77% and that of intraoperative tissue to 55%, while it remained 100% for blood culture-inoculated sonication fluid. The time to positivity was shorter in blood culture-inoculated sonication fluid, with detection of 72% of microorganisms after 1 day of incubation, than for intraoperative tissue and conventional sonication fluid cultures, with detection of 18% and 28% of microorganisms, respectively. In conclusion, compared to conventional sonication fluid and intraoperative tissue cultures, sonication fluid inoculated into blood culture bottles improved the diagnosis of OIAI and considerably reduced the time to culture positivity.

Effect of probiotics (Saccharomyces boulardii) on microbial translocation and inflammation in HIV-treated patients: a double-blind, randomized, placebo-controlled trial.

BACKGROUND: Microbial translocation has been associated with an increase in immune activation and inflammation in HIV infection despite effective highly active antiretroviral therapy. It has been shown that some probiotics have a beneficial effect by reducing intestinal permeability and, consequently, microbial translocation. OBJECTIVES: To assess changes in microbial translocation and inflammation after treatment with probiotics (Saccharomyces boulardii) in HIV-1-infected patients with virologic suppression. METHODS: A double-blind, randomized, placebo-controlled trial was conducted in 44 nonconsecutive HIV-1-infected patients with viral load of <20 copies per milliliter for at least 2 years. Patients were randomized to oral supplementation with probiotics or placebo during 12 weeks. Markers of microbial translocation (lipopolysaccharide-binding protein [LBP] and soluble CD14), inflammation (interleukin 6 [IL-6], tumor necrosis factor alpha, interferon gamma, high-sensitivity C-reactive protein), and immunological and clinical data were determined before and after the intervention and 3 months after treatment discontinuation. Quantitative variables were compared using the Mann-Whitney U test, and categorical variables were compared using the Fisher exact test. RESULTS: After 12 weeks of treatment, differences between the probiotic arm and the placebo arm were observed in LBP values (-0.30 vs +0.70 pg/mL) and IL-6 (-0.60 vs +0.78 pg/mL). These differences were also noted at 3 months after treatment withdrawal. Qualitative analysis was performed, defining a variable as "decreased" or "increased" from baseline LBP. A significant decrease of LBP at 12 weeks of treatment was observed (57.9% patients in the probiotic group vs 6.2% in the placebo group, P = 0.002). CONCLUSIONS: Treatment with S. boulardii decreases microbial translocation (LBP) and inflammation parameters (IL-6) in HIV-1-infected patients with long-term virologic suppression.

Advantages of sonication fluid culture for the diagnosis of prosthetic joint infection.

OBJECTIVES: The sensitivity of periprosthetic tissue culture is inadequate for the diagnosis of prosthetic joint infection (PJI). We investigated and compared the values of sonication fluid culture and periprosthetic tissue culture for diagnosing PJI. METHODS: Included were patients whose joint prosthesis had been removed for any reason. The resulting sonication fluid and periprosthetic tissues were cultured for 14 days. RESULTS: Of 231 explanted prostheses, aseptic failure was diagnosed in 162 cases (70%) and PJI in 69 (30%). In PJI cases, sonication fluid culture detected 62 microorganisms and periprosthetic tissue culture detected 45. Tissue and sonication fluid cultures showed sensitivities of 61% and 81%, respectively (p < 0.01), with specificity of 100% and 99%, respectively. On day 1, tissue and sonication fluid cultures were positive in 13% and 28% (p = 0.013) of PJI cases respectively, and on day 2, in 26% and 48% (p = 0.002) of cases. Four anaerobes grew in sonication fluid culture after 7-13 days incubation, whereas tissue culture missed 3 of these. Prolonged incubation of sonication fluid did not detect any organisms in the cases of aseptic failure. CONCLUSIONS: Sonication fluid culture provides a more rapid diagnosis and detects about 30% more pathogens, although anaerobic organisms require up to 2 weeks of incubation.

Prosthesis failure within 2 years of implantation is highly predictive of infection.

BACKGROUND: The outcome of revision surgery depends on accurate determination of the cause of prosthesis failure because treatment differs profoundly among aseptic loosening, mechanical failure, and prosthetic joint infections (PJI). QUESTIONS/PURPOSES: We sought to determine (1) the predictive role of the interval from primary to revision surgery in determining the reason for prosthesis failure of a hip, knee, shoulder, or elbow arthroplasty, and (2) whether positive cultures during revision surgery for aseptic loosening were associated with shorter event-free survival of the prosthesis. METHODS: All patients undergoing revision surgery between July 2010 and January 2012 were included in a prospective cohort of 112 patients, and were classified as having had failure from aseptic loosening (56%), mechanical failure (15%), or PJI (29%). To make the diagnosis of PJI, at surgery we used a standardized enhanced diagnostic approach in all patients including sampling of five periprosthetic tissue specimens, sonication of removed prosthetic components, prolonged incubation of aerobic and anaerobic cultures, and multiplex PCR of sonication fluid in aseptic loosening cases. Kaplan-Meier survival and Cox proportional hazards regression analysis were performed. RESULTS: The median time from primary to revision surgery was (p < 0.001) longer for patients with aseptic loosening (7.8 years) than for patients with mechanical failure (1.6 years) or PJI (2 years). No difference in the time to revision was observed for patients with aseptic loosening with positive or negative microbiological cultures (p = 0.594). Propionibacterium acnes was cultured below the established microbiological criteria for positivity in 12 (19%) procedures that had been presumed to have been revisions for aseptic loosening. CONCLUSIONS: PJI should be considered in all revisions performed within 2 years of implantation even in the absence of clinical or laboratory findings suggestive for infection. However, the growth of low-virulence microorganisms below the cut-off in revisions for apparent aseptic loosening is not associated with early prosthesis failure.

Sonication versus vortexing of implants for diagnosis of prosthetic joint infection.

Biofilm removal efficacy of vortexing alone was compared with the standard vortexing-sonication procedure. Among 135 removed prostheses, 35 were diagnosed with infection and 100 with aseptic failure. At a cutoff of ≥ 50 CFU/ml, sonication was more sensitive than vortexing (60% versus 40%, P = 0.151), while the specificity was 99% for both methods.

Multiplex PCR of sonication fluid accurately differentiates between prosthetic joint infection and aseptic failure.

OBJECTIVE: Cultures have limited sensitivity in the diagnosis of prosthetic joint infection (PJI), especially in low-grade infections. We assessed the value of multiplex PCR in differentiating PJI from aseptic failure (AF). METHODS: Included were patients in whom the joint prosthesis was removed and submitted for sonication. The resulting sonication fluid was cultured and investigated by multiplex PCR, and compared with periprosthetic tissue culture. RESULTS: Among 86 explanted prostheses (56 knee, 25 hip, 3 elbow and 2 shoulder prostheses), AF was diagnosed in 62 cases (72%) and PJI in 24 cases (28%). PJI was more common detected by multiplex PCR (n=23, 96%) than by periprosthetic tissue (n=17, 71%, p=0.031) or sonication fluid culture (n=16, 67%, p=0.016). Among 12 patients with PJI who previously received antibiotics, periprosthetic tissue cultures were positive in 8 cases (67%), sonication fluid cultures in 6 cases (50%) and multiplex PCR in 11 cases (92%). In AF cases, periprosthetic tissue grew organisms in 11% and sonication fluid in 10%, whereas multiplex PCR detected no organisms. CONCLUSIONS: Multiplex PCR of sonication fluid demonstrated high sensitivity (96%) and specificity (100%) for diagnosing PJI, providing good discriminative power towards AF, especially in patients previously receiving antibiotics.

[Predictive factors for pneumonia in adults infected with the new pandemic A (H1H1) influenza virus]. / Factores predictivos de neumonía en pacientes infectados por el nuevo virus de la gripe A (H1N1) pandémica.

BACKGROUND: On April 2009 a new A (H1N1) influenza virus was identified with a higher incidence of severe outcome in younger people, most of them with pneumonia. The objective of our study was to identify the predictive risk factors of pneumonia in patients with the new A (H1N1) influenza virus infection. METHODS: Prospective cohort study of adults infected with the new A (H1N1) influenza virus, admitted in a universitary hospital, from june 2009 to January 2010. Pneumonia was defined as the presence of any pulmonary infiltrate of any distribution with no other evident cause, in the chest radiography. A comparative analysis was made with patients with A (H1N1) influenza without pneumonia. RESULTS: 281 patients with influenza A (H1N1) were treated. Thirty of them (10.6%) had pneumonia and 11 (3.9%) required intensive care. The global mortality was 0.7%. For the comparative analysis, 42 patients with influenza A (H1N1) without pneumonia were analysed (20 hospitalized and 22 nonhospitalised). In the multivariate analysis, obesity (BMI>30), (OR: 3.8; IC 95%: 0.99-15.0), time since symptom onset until hospital admission (OR 1.34; IC 95% 1.04-1.72), serum C reactive protein levels (OR:1.10; IC 95%: 0.98-1.24) and serum IgG2 levels (OR:1.08; IC 95%: 1.0- 1.01), were identified as independent risk factors for pneumonia. CONCLUSION: Obesity, delay in medical care and higher levels of C reactive protein and IgG2 were predictive factors for pneumonia in adult patients with A (H1N1) influenza infection.

Factores predictivos de neumonía en pacientes infectados por el nuevo virus de la gripe A (H1N1) pandémica / Predictive factors for pneumonia in adults infected with the new pandemic A (H1H1) influenza virus

Introducción: en abril de 2009 se identificó un nuevo virus de la gripe A H1N1 con mayor incidencia de casos graves en pacientes jóvenes, con afectación pulmonar en forma de neumonía en la mayoría de ellos. El objetivo de este estudio fue identificar los factores predictivos de neumonía en pacientes infectados por el nuevo virus de la gripe A (H1N1). Métodos: estudio de cohortes prospectivo de casos de infección por el virus de la gripe A (H1N1), en adultos, de junio de 2009 a enero de 2010, en un hospital universitario. Se definió neumonía como la presencia de infiltrado de cualquier tipo y distribución en la radiografía de tórax, sin otra causa evidente. Se realizó un análisis comparativo con pacientes con gripe A (H1N1) sin neumonía. Resultados: Se atendieron 281 pacientes adultos con gripe A (H1N1). De ellos 30 (10.6%) tenían neumonía. y 11 (3,9%) precisaron cuidados intensivos. La mortalidad global fue del 0,7%. Para el análisis comparativo se analizaron 42 pacientes con gripe A H1N1 sin neumonía (20 ingresados y 22 ambulatorios). En el análisis multivariado se identificaron como factores de riesgo de neumonía un IMC >30 (OR: 3,8; IC 95%: 0,99- 15,0), los días transcurridos desde el inicio de los síntomas hasta el ingreso hospitalario (OR 1,34; IC 95% 1,04-1,72), los niveles de PCR (OR:1,10; IC 95%: 0,98-1,24) y de IgG subtipo 2 (OR: 1,08; IC 95%: 1,0- 1,01). Conclusiones: la obesidad, el retraso en la atención sanitaria, y unos niveles elevados de PCR e IgGsub2 fueron factores predictivos de neumonía en pacientes adultos con gripe A H1N1(AU)

Background: On April 2009 a new A (H1N1) influenza virus was identified with a higher incidence of severe outcome in younger people, most of them with pneumonia. The objective of our study was to identify the predictive risk factors of pneumonia in patients with the new A (H1N1) influenza virus infection. Methods: Prospective cohort study of adults infected with the new A (H1N1) influenza virus, admitted in a universitary hospital, from june 2009 to January 2010. Pneumonia was defined as the presence of any pulmonary infiltrate of any distribution with no other evident cause, in the chest radiography. A comparative analysis was made with patients with A (H1N1) influenza without pneumonia. Results: 281 patients with influenza A (H1N1) were treated. Thirty of them (10.6%) had pneumonia and 11 (3.9%) required intensive care. The global mortality was 0.7%. For the comparative analysis, 42 patients with influenza A (H1N1) without pneumonia were analysed (20 hospitalized and 22 nonhospitalised). In the multivariate analysis, obesity (BMI>30), (OR: 3.8; IC 95%: 0.99-15.0), time since symptom onset until hospital admission (OR 1.34; IC 95% 1.04-1.72), serum C reactive protein levels (OR:1.10; IC 95%: 0.98-1.24) and serum IgG2 levels (OR:1.08; IC 95%: 1.0- 1.01), were identified as independent risk factors for pneumonia. Conclusion: Obesity, delay in medical care and higher levels of C reactive protein and IgG2 were predictive factors for pneumonia in adult patients with A (H1N1) influenza infection(AU)

Spread of plasmids containing the bla(VIM-1) and bla(CTX-M) genes and the qnr determinant in Enterobacter cloacae, Klebsiella pneumoniae and Klebsiella oxytoca isolates.

OBJECTIVES: We describe 12 VIM-1-producing strains (7 Enterobacter cloacae, 2 Klebsiella pneumoniae and 3 clonal Klebsiella oxytoca strains) detected among clinically relevant Enterobacteriaceae isolates from routine cultures at the Hospital del Mar (Barcelona, Spain) from December 2006 to May 2007. METHODS: Susceptibility to carbapenems was evaluated with the MicroScan system. beta-Lactamases were identified by PCR and sequencing. Clonal relationships between the isolates were analysed by PFGE. Transferability of the enzymes was tested by conjugation. Plasmid characterization was performed by PCR-based replicon typing and PFGE with S1 nuclease digestion of whole genomic DNA. The PFGE gels were then transferred and hybridized. RESULTS: The disc diffusion method correctly identified five of the seven E. cloacae isolates as intermediate or resistant strains. All isolates produced the VIM-1 enzyme. Three E. cloacae and three K. oxytoca strains were also CTX-M-9-producing strains, and one E. cloacae was also a CTX-M-3-producing strain. The plasmids carrying the bla(VIM) gene, of unknown incompatibility group, had a size of approximately 75 kb (eight strains) or 40 kb (three strains) and also contained the qnrS and the aac(6')-Ib-cr genes. In the remaining strain the bla(VIM-1) gene was found in an HI2 plasmid of 290 kb together with bla(CTX-M-9), qnrA, qnrS and the aac(6')-Ib-cr genes. CONCLUSIONS: The results showed a linkage between the bla(VIM-1) and the qnrS and the aac(6')-Ib-cr genes, and between the bla(CTX-M-9) and the qnrA genes.