The Incidence and Incubation Period of False Positive Cultures in Shoulder Surgery

The Incidence and Incubation Period of False Positive Cultures in Shoulder Surgery Study Protocol: A Pilot Study

This study will describe the time point at which a positive culture from a patient who has undergone shoulder surgery should be treated as an infection versus a false positive result that should be disregarded. Intraoperative biopsies will be taken and cultured from 50 subjects who have undergone an "open" surgical procedure and 50 from subjects undergoing an arthroscopic procedure.

Study Overview

• Status: Completed
• Conditions: Infection
• Intervention / Treatment: Other: Culture

Detailed Description

Postoperative infection is a significant complication that requires timely identification and treatment. Indolent infections, such as those involving Propionibacterium acnes (P. acnes), pose a diagnostic dilemma as they present differently than the acute symptoms typically associated with most postoperative bone and joint infections. The workup of these suspected infections is also somewhat difficult, as these colonies are slow growing, necessitating that cultures be kept for an extended period of time. Previous studies have shown that positive cultures are typically identified between 7 and 13 days. In a recent study of patients undergoing primary shoulder arthroplasty, 41.8% of patients were found to have P. acnes growth from their joint fluid at a mean of 7 days (range 5-9 days). All of these patients were then treated immediately with 4 weeks of dual oral antibiotic therapy1.

As the incubation of laboratory cultures increases, there is the potential concern of false positive growth. Timely identification is critical in order to avoid performing unnecessary treatments on patients in whom no infection is actually present.

The investigators will enroll patients undergoing primary shoulder surgery for a clearly identified mechanical dysfunction, in which there is no clinical suspicion for infection. Infection should not exist in this population, making it an appropriate clinical sample in which to study results that the investigators would consider to be false positives.

• Study Type: Observational
• Enrollment (Actual): 100

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Patients with mechanical problems associated with their shoulder who elect to undergo shoulder surgery

Description

Inclusion Criteria:

• Patients undergoing primary open and arthroscopic shoulder surgery in which there is a clear diagnosis of a mechanical problem that is felt to be amenable to surgical intervention and there is no suspicion of infection. Examples include, but are not limited to: rotator cuff tear, labral tear, instability, impingement, and osteoarthritis.

Exclusion Criteria:

• Prior shoulder surgery
• Prior glenohumeral injection within the last 6 months
• Systemic or shoulder inflammatory disorder
• Any clinical, imaging, or laboratory findings that raise suspicion of infection
• Minors
• Erythrocyte sedimentation rate (ESR) >15 mm/hr for males less than 50 years old, >20 mm/hr for males greater than 50 years old and females less than 50 years old, and >30 mm/hr for females greater than 50 years old
• C reactive protein (CRP) >1 mg/d,
• Procalcitonin (PCT) >0.05 ng/ml.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Open Shoulder Surgery; Culture	Other: Culture; Specimens will be obtained and sent to the lab for cultures.
Arthroscopic Shoulder Surgery; Culture	Other: Culture; Specimens will be obtained and sent to the lab for cultures.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Incidence of positive cultures	28 days

Secondary Outcome Measures

Outcome Measure	Time Frame
Incubation time clarification for culture growth if it occurs	Less than or equal to 28 days

Collaborators and Investigators

• Sponsor: Forte Sports Medicine and Orthopedics
• Investigators: Principal Investigator: Gary Misamore, MD, Forte Sports Medicine and Orthopedics

Publications and helpful links

General Publications

• Butler-Wu SM, Burns EM, Pottinger PS, Magaret AS, Rakeman JL, Matsen FA 3rd, Cookson BT. Optimization of periprosthetic culture for diagnosis of Propionibacterium acnes prosthetic joint infection. J Clin Microbiol. 2011 Jul;49(7):2490-5. doi: 10.1128/JCM.00450-11. Epub 2011 May 4.
• Levy O, Iyer S, Atoun E, Peter N, Hous N, Cash D, Musa F, Narvani AA. Propionibacterium acnes: an underestimated etiology in the pathogenesis of osteoarthritis? J Shoulder Elbow Surg. 2013 Apr;22(4):505-11. doi: 10.1016/j.jse.2012.07.007. Epub 2012 Sep 13.

Study record dates

Study Major Dates

• Study Start: May 1, 2015
• Primary Completion (Actual): March 1, 2018
• Study Completion (Actual): March 1, 2018

Study Registration Dates

• First Submitted: April 25, 2015
• First Submitted That Met QC Criteria: November 9, 2015
• First Posted (Estimate): November 11, 2015

Study Record Updates

• Last Update Posted (Actual): August 16, 2018
• Last Update Submitted That Met QC Criteria: August 14, 2018
• Last Verified: August 1, 2018

More Information

Terms related to this study

• Keywords: infection; Propionibacterium acnes; shoulder surgery
• Additional Relevant MeSH Terms: Infections
• Other Study ID Numbers: 1407463823

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES