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Paper of the week: Large variations in clinical antibiotic activity against Staphylococcus aureus biofilms of periprosthetic joint infection isolates.

Paper of the week: Large variations in clinical antibiotic activity against Staphylococcus aureus biofilms of periprosthetic joint infection isolates. Mandell JB, Orr S, Koch J, Nourie B, Ma D, Bonar DD, Shah N, Urish KL. J Orthop Res. 2019 Mar 27. doi: 10.1002/jor.24291

Summary by Dr Sreeram Penna

In this study researchers assessed the efficacy of various antibiotics against staphylococcal aureus bacterial isolates in both planktonic and biofilm stages. They have measured minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for isolates in planktonic state and minimum biofilm inhibitory concentration (MBIC) and minimum biofilm bactericidal concentration (MBBC) for bacteria isolates grown in biofilm state. They have tested two lab strains USA300 and SH1000 and 10 Methicillin resistant Staphylococcus aureus (MRSA) clinical isolates and 8 Methicillin sensitive Staphylococcus aureus (MSSA) clinical isolates. They have tested these isolates against various dilutions of vancomycin, rifampin, gentamycin, trimethoprim/sulphamethoxazole, doxycycline and daptomycin. In addition to above MSSA isolates were tested with cefazolin and nafcillin and MRSA isolates were tested with clindamycin and linezolid.

Results showed that across the bacterial isolates MIC concentrations varied largely for gentamicin, trimethoprim/sulfamethoxazole and vancomycin (approximately 1.5 log spread) and smaller variation (0.5 log spread) for rifampin, doxycycline, and daptomycin. Similarly, MBC concentrations varied significantly (2 log spread) for all antibiotics. Rifampin was superior to other antibiotics against planktonic cultures with MBC concentrations ranging from 0.13 to 8 microgram / ml. With biofilm isolates most antibiotics showed significant variability (2 to 3 log spreads) in MBIC except daptomycin. Of all the antibiotics tested only rifampin, doxycycline, and daptomycin had impact on 48-hour mature biofilms, with biofilm MBCs ranging from 80 to 2000 μg/ml. In conclusion this research shows variable impact of antibiotics on different strain isolates and also difference in susceptibilities of isolates in planktonic stages versus biofilm stages.

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Paper of the week: Modifiable Factors as Current Smoking, Hypoalbumin, and Elevated Fasting Blood Glucose Level Increased the SSI Risk Following Elderly Hip Fracture Surgery.

Paper of the week: Modifiable Factors as Current Smoking, Hypoalbumin, and Elevated Fasting Blood Glucose Level Increased the SSI Risk Following Elderly Hip Fracture Surgery. Ma T, Lu K, Song L, Wang D, Ning S, Chen Z, Wu Z. J Invest Surg. 2019 Mar 19:1-9. doi: 10.1080/08941939.2018.1556364.

Summary by Dr Sreeram Penna

Aim of this retrospective study was to find incidence of infection post hip fracture surgery in elderly population. In addition, researchers were also looking for independent risk factors associated with infection in this cohort. Infections were classified in to superficial and deep infections based on combination of clinical findings of persistent wound discharge, wound dehiscence, gangrene and abscess development, need for surgical intervention and positive cultures. 611 patients were included in the final study. Over all infection incidence was 4.4% (27/611), superficial infection was 3.1% (21/611) and deep infection was 1.3% (6/611). Multivariate analysis showed that body mass index, current smoking, surgical duration of more than 2 hours, preoperative hospital stay more than 7 days, ASA class of III and IV, albumin levels less than 35 gram per liter, and fasting blood glucose more than 110 mg/dl were know to be independent risk factors for development of infection following hip fracture surgery.

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Paper of the week: Perioperative Antibiotic Prophylaxis in Total Joint Arthroplasty: A Single Dose Is as Effective as Multiple Doses.

Paper of the week: Perioperative Antibiotic Prophylaxis in Total Joint Arthroplasty: A Single Dose Is as Effective as Multiple Doses. Tan TL, Shohat N, Rondon AJ, Foltz C, Goswami K, Ryan SP, Seyler TM, Parvizi J. J Bone Joint Surg Am. 2019 Mar 6;101(5):429-437. doi: 10.2106/JBJS.18.00336.

Summary by Dr. Sreeram Penna

This study is a retrospective study comparing the incidence of periprosthetic joint infection (PJI) in primary joint arthroplasty who had a single dose of prophylactic antibiotic versus multiple doses at the time of surgery. A total of 20,682 patients were included in the study. Of these 4523 had a single dose and 16159 had multiple doses. All patients who had an infection within 1 year were identified and confirmed with MSIS criteria. In addition, researchers calculated and recorded the patient’s preoperative infection risk score.

The results showed that overall rates of PJI were 0.60% (27/4523) in patients receiving a single dose and 0.88% (142/16159) in patients receiving multiple prophylactic antibiotic doses. Researchers also noted that both patient groups were significantly different in various demographics (age, sex, BMI, comorbidities, ASA score, length of stay). Researchers then performed multivariate analysis after controlling for potential confounders and found no significant difference between the PJI rate between both groups. They have also used propensity score matching with preoperative risk score and found no increase in PJI rate in patients with a single dose of prophylactic antibiotic at the primary procedure.

Although this study has limitations of being retrospective study and statistically significant differences between two groups, it provides the necessary evidence to support the use of single-dose prophylactic antibiotic during primary joint arthroplasty.

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ICM document update: Spanish translation completed

ICM document Spanish translation is completed. It is available online at the following link.

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ICM symposium at AAOS info and ICM book availability updates

Dear Delegates, For those of you who may be attending the AAOS next week, we wanted to let you know that copies of the ICM book will be distributed during the ICM symposium to be held on Thursday 6-7:30 PM at Titan Room Venetian(sponsored by Convatec) and also another symposium on the same day from 9-10:30 PM at Tao, Venetian(Sponsored by Heraeus). In addition, our industry partners Aerobiotix, Acelity, and MicrogenDx, have agreed to have copies of the book for distribution in their booth.

See you in Vegas

Have you checked out the new version of the PJIDx on the App?