Jayawant N. Mandrekar

Outcome of Prosthetic Joint Infections Treated with Debridement and Retention of Components

BACKGROUND Debridement and retention of the prosthesis represents an attractive surgical modality for treatment of prosthetic joint infection, but risk factors for treatment failure require clarification. METHODS We conducted a retrospective cohort analysis of all patients with a prosthetic joint infection who were treated with debridement and retention of the prosthesis at the Mayo Clinic (Rochester, Minnesota) between 1995 and 1999. RESULTS Debridement and retention of the prosthesis was the initial treatment modality for 99 episodes of prosthetic joint infection that occurred in 91 patients who presented to the Mayo Clinic during 1995-1999. A total of 32% and 23% of all episodes were due to Staphylococcus aureus and coagulase-negative staphylococci, respectively. The median duration of intravenous antimicrobial therapy was 28 days (range, 1-90 days). Oral antimicrobial suppression was used in 89% of the episodes, for a median duration of 541 days (range, 5-2673 days). Treatment failure occurred in 53 episodes during a median follow-up period of 700 days (range, 1-2779 days). The 2-year survival rate free of treatment failure was 60% (95% confidence interval [CI], 50%-71%). Variables associated with an increased risk of treatment failure in multivariable analysis included the presence of a sinus tract (hazard ratio, 2.84; 95% CI, 1.48-5.44; P = .002) and a duration of symptoms prior to debridement of > or = 8 days (hazard ratio, 1.77; 95% CI, 1.02-3.07; P = .04). CONCLUSIONS Debridement and retention of the prosthesis is a common surgical modality at our institution to treat prosthetic joint infection. Risk factors independently associated with treatment failure include the presence of a sinus tract and duration of symptoms prior to debridement of > or = 8 days.

Incidence and outcome of cervical artery dissection A population-based study

Background: Incidence rates for internal carotid artery dissection (ICAD) have been reported to be 2.6 to 2.9 per 100,000, but reliable epidemiologic data for vertebral artery dissection (VAD) are not available. Objective: To determine the incidence rate of cervical artery dissection (CAD) in a defined population. Methods: With IRB approval, we used the medical record linkage system of the Rochester Epidemiology Project to identify all patients diagnosed with spontaneous ICAD and VAD for the period of 1987–2003 in Olmsted County, MN. Results: Of 48 patients with CAD, there were 32 patients with ICAD and 18 patients with VAD. In Olmsted County, the average annual incidence rate for ICAD was 1.72 per 100,000 population (95% CI, 1.13 to 2.32) and for VAD 0.97 per 100,000 population (95% CI, 0.52 to 1.4). The average annual incidence rate for CAD was 2.6 per 100,000 population (95% CI, 1.86 to 3.33). The most frequently encountered symptoms in CAD were head or neck pain (80%), cerebral ischemia (TIA or infarct) (56%), and Horner syndrome (25%). Good outcome (defined as modified Rankin score of 0 to 2) was seen in 92% of patients. No recurrence of dissection was observed during a mean 7.8 years of follow-up. Conclusions: Internal carotid artery dissection was detected approximately twice as frequently as vertebral artery dissection in the overall study, but in the latter half of the study period, vertebral artery and internal carotid artery dissection incidence rates were equivalent. The majority of cervical artery dissection patients in the community have excellent outcome, and contrary to many tertiary referral series, re-dissection is rare.

Prospective Comparison of State-of-the-Art MR Enterography and CT Enterography in Small-Bowel Crohn's Disease

OBJECTIVE The objective of our study was to prospectively obtain pilot data on the accuracy of MR enterography for detecting small-bowel Crohns disease compared with CT enterography and with a clinical reference standard based on imaging, clinical information, and ileocolonoscopy. SUBJECTS AND METHODS The study group for this blinded prospective study was composed of 33 patients with suspected active Crohns ileal inflammation who were scheduled for clinical CT enterography and ileocolonoscopy and had consented to also undergo MR enterography. The MR enterography and CT enterography examinations were each interpreted by two radiologists with disagreements resolved by consensus. The reports from ileocolonoscopy with or without mucosal biopsy were interpreted by a gastroenterologist. The reference standard for the presence of small-bowel Crohns disease was based on the final clinical diagnosis by the referring gastroenterologist after reviewing all of the available information. RESULTS All 33 patients underwent CT enterography and ileocolonoscopy, 30 of whom also underwent MR enterography. The sensitivities of MR enterography and CT enterography for detecting active small-bowel Crohns disease were similar (90.5% vs 95.2%, respectively; p = 0.32). The image quality scores for MR enterography examinations were significantly lower than those for CT enterography (p = 0.005). MR enterography and CT enterography identified eight cases (24%) with a final diagnosis of active small-bowel inflammation in which the ileal mucosa appeared normal at ileocolonoscopy. Furthermore, enterography provided the only available imaging in three additional patients who did not have ileal intubation. CONCLUSION MR enterography and CT enterography have similar sensitivities for detecting active small-bowel inflammation, but image quality across the study cohort was better with CT. Cross-sectional enterography provides complementary information to ileocolonoscopy.

Patient Outcomes After Vestibular Schwannoma Management: a Prospective Comparison of Microsurgical Resection and Stereotactic Radiosurgery

OBJECTIVE The best management for patients with small- to medium-sized vestibular schwannomas (VS) is controversial. METHODS : A prospective cohort study of 82 patients with unilateral, unoperated VS less than 3 cm undergoing surgical resection (n = 36) or radiosurgery (n = 46). Patients undergoing resection were younger (48.2 yr versus 53.9 yr, P = 0.03). The groups were similar with regard to hearing loss, associated symptoms, and tumor size. The mean follow-up period was 42 months (range, 12-62 mo). RESULTS Normal facial movement and preservation of serviceable hearing was more frequent in the radiosurgical group at 3 months (P < 0.001), 1 year (P < 0.001), and at the last follow-up examination (P < 0.01) compared with the surgical resection group. Patients undergoing surgical resection had a significant decline in the following subscales of the Health Status Questionnaire 3 months after surgery: physical functioning (P = 0.006), role-physical (P < 0.001), energy/fatigue (P = 0.02), and overall physical component (P = 0.004). Patients in the surgical resection group continued to have a significant decline in the physical functioning (P = 0.04) and bodily pain (P = 0.04) subscales at 1 year and in bodily pain (P = 0.02) at the last follow-up examination. The radiosurgical group had no decline on any component of the Health Status Questionnaire after the procedure. The radiosurgical group had lower mean Dizziness Handicap Inventory scores (16.5 versus 8.4, P = 0.02) at the last follow-up examination. There was no difference in tumor control (100 versus 96%, P = 0.50). CONCLUSION Early outcomes were better for VS patients undergoing stereotactic radiosurgery compared with surgical resection (Level 2 evidence). Unless long-term follow-up evaluation shows frequent tumor progression at currently used radiation doses, radiosurgery should be considered the best management strategy for the majority of VS patients.

Subcutaneous IGF-1 is not beneficial in 2-year ALS trial

Background: Previous human clinical trials of insulin-like growth factor type I (IGF-1) in amyotrophic lateral sclerosis (ALS) have been inconsistent. This phase III, randomized, double-blind, placebo-controlled study was undertaken to address whether IGF-1 benefited patients with ALS. Methods: A total of 330 patients from 20 medical centers were randomized to receive 0.05 mg/kg body weight of human recombinant IGF-1 given subcutaneously twice daily or placebo for 2 years. The primary outcome measure was change in their manual muscle testing score. Secondary outcome measures included tracheostomy-free survival and rate of change in the revised ALS functional rating scale. Intention to treat analysis was used. Results: There was no difference between treatment groups in the primary or secondary outcome measures after the 2-year treatment period. Conclusions: Insulin-like growth factor type I does not provide benefit for patients with amyotrophic lateral sclerosis. GLOSSARY: ALS = amyotrophic lateral sclerosis; ALSFRS-r = revised ALS functional rating scale; AUC = area under the curve; DVT = deep venous thromboses; IGF-1 = insulin-like growth factor type I; MMT = manual muscle testing; PE = pulmonary embolisms.

Dental Procedures as Risk Factors for Prosthetic Hip or Knee Infection: A Hospital-Based Prospective Case-Control Study

BACKGROUND The actual risk of prosthetic joint infection as a result of dental procedures and the role of antibiotic prophylaxis have not been defined. METHODS To examine the association between dental procedures with or without antibiotic prophylaxis and prosthetic hip or knee infection, a prospective, single-center, case-control study for the period 2001-2006 was performed at a 1200-bed tertiary care hospital in Rochester, Minnesota. Case patients were patients hospitalized with total hip or knee infection. Control subjects were patients who underwent a total hip or knee arthroplasty but without a prosthetic joint infection who were hospitalized during the same period on the same orthopedic floor. Data regarding demographic features and potential risk factors were collected. Logistic regression was used to assess the association of variables with the odds of infection. RESULTS A total of 339 case patients and 339 control subjects were enrolled in the study. There was no increased risk of prosthetic hip or knee infection for patients undergoing a high-risk or low-risk dental procedure who were not administered antibiotic prophylaxis (adjusted odds ratio [OR], 0.8; 95% confidence interval [CI], 0.4-1.6), compared with the risk for patients not undergoing a dental procedure (adjusted OR, 0.6; 95% CI, 0.4-1.1) respectively. Antibiotic prophylaxis in high-risk or low-risk dental procedures did not decrease the risk of subsequent total hip or knee infection (adjusted OR, 0.9 [95% CI, 0.5-1.6] and 1.2 [95% CI, 0.7-2.2], respectively). CONCLUSIONS Dental procedures were not risk factors for subsequent total hip or knee infection. The use of antibiotic prophylaxis prior to dental procedures did not decrease the risk of subsequent total hip or knee infection.

Comparison of Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometer to BD Phoenix Automated Microbiology System for Identification of Gram-Negative Bacilli

ABSTRACT We compared the BD Phoenix automated microbiology system to the Bruker Biotyper (version 2.0) matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) system for identification of Gram-negative bacilli, using biochemical testing and/or genetic sequencing to resolve discordant results. The BD Phoenix correctly identified 363 (83%) and 330 (75%) isolates to the genus and species level, respectively. The Bruker Biotyper correctly identified 408 (93%) and 360 (82%) isolates to the genus and species level, respectively. The 440 isolates were grouped into common (308) and infrequent (132) isolates in the clinical laboratory. For the 308 common isolates, the BD Phoenix and Bruker Biotyper correctly identified 294 (95%) and 296 (96%) of the isolates to the genus level, respectively. For species identification, the BD Phoenix and Bruker Biotyper correctly identified 93% of the common isolates (285 and 286, respectively). In contrast, for the 132 infrequent isolates, the Bruker Biotyper correctly identified 112 (85%) and 74 (56%) isolates to the genus and species level, respectively, compared to the BD Phoenix, which identified only 69 (52%) and 45 (34%) isolates to the genus and species level, respectively. Statistically, the Bruker Biotyper overall outperformed the BD Phoenix for identification of Gram-negative bacilli to the genus (P < 0.0001) and species (P = 0.0005) level in this sample set. When isolates were categorized as common or infrequent isolates, there was statistically no difference between the instruments for identification of common Gram-negative bacilli (P > 0.05). However, the Bruker Biotyper outperformed the BD Phoenix for identification of infrequently isolated Gram-negative bacilli (P < 0.0001).

Comparison of direct colony method versus extraction method for identification of gram-positive cocci by use of Bruker biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry

ABSTRACT We evaluated Bruker Biotyper (version 2.0) matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) for the identification of 305 clinical isolates of staphylococci, streptococci, and related genera by comparing direct colony testing with preparatory extraction. Isolates were previously identified by use of phenotypic testing and/or 16S rRNA gene sequencing. Manufacturer-specified score cutoffs for genus- and species-level identification were used. After excluding 7 isolates not present in the Biotyper library, the Biotyper correctly identified 284 (95%) and 207 (69%) isolates to the genus and species levels, respectively, using extraction. By using direct colony testing, the Biotyper identified 168 (56%) and 60 (20%) isolates to the genus and species levels, respectively. Overall, more isolates were identified to the genus and species levels with preparatory extraction than with direct colony testing (P < 0.0001). The analysis was repeated after dividing the isolates into two subgroups, staphylococci, streptococci, and enterococci (n = 217) and “related genera” (n = 81). For the former subgroup, the extraction method resulted in the identification of 213 (98%) and 171 (79%) isolates to the genus and species levels, respectively, whereas the direct colony method identified 136 (63%) and 56 (26%) isolates to the genus and species levels, respectively. In contrast, for the subgroup of related genera, the extraction method identified 71 (88%) and 36 (44%) isolates to the genus and species levels, respectively, while the direct colony method identified 32 (40%) and 4 (5%) isolates to the genus and species levels, respectively. For both subgroups, preparatory extraction was superior to direct colony testing for the identification of isolates to the genus and species levels (P < 0.0001). Preparatory extraction is needed for the identification of a substantial proportion of Gram-positive cocci using the Biotyper method according to manufacturer-specified score cutoffs.

Predictors of Outcome in Refractory Status Epilepticus

OBJECTIVE To further characterize the demographics, outcomes, and prognostic factors for refractory status epilepticus (RSE). DESIGN Retrospective analysis of all the episodes of RSE treated between January 1, 1999, and August 30, 2011. SETTING Neurointensive care unit within a tertiary referral center, Mayo Clinic, Rochester, Minnesota. PATIENTS Refractory status epilepticus was defined as generalized convulsive or nonconvulsive status epilepticus (SE) that continued despite initial first- and second-line therapies. Exclusion criteria were aged younger than 18 years, anoxic/myoclonic SE, psychogenic SE, simple partial SE, and absence SE. MAIN OUTCOME MEASURES Functional outcome was defined by modified Rankin scale (mRS) dichotomized into good (mRS, 0-3) and poor (mRS, 4-6). Functional decline was defined as a change in mRS greater than 1 from hospital admission to discharge. RESULTS We identified 63 consecutive episodes of non-anoxic RSE in 54 patients. Anesthetic agents were used in 55 episodes (87.30%), and duration of drug-induced coma was (mean [SD]) 11.0 (17.9) days. In-hospital mortality was 31.75% (20 of 63 episodes). Poor functional outcome at discharge occurred in 48 of 63 episodes (76.19%). Hospital length of stay was (mean [SD]) 27.7 (37.3) days. Duration of drug-induced coma (P=.03), arrhythmias requiring intervention (P=.01), and pneumonia (P=.01) were associated with poor functional outcome. Prolonged mechanical ventilation was associated with mortality (P=.04). Seizure control without suppression-burst or isoelectric electroencephalogram predicted good functional recovery (P=.01). Age, history of epilepsy, previous SE, type of SE, and anesthetic drug used were not associated with functional outcome. CONCLUSIONS Three-quarters of patients with RSE have a poor outcome. Achieving control of the SE without requiring prolonged drug-induced coma or severe electroencephalographic suppression portends better prognosis.

Outcome of Prosthetic Joint Infection in Patients with Rheumatoid Arthritis: The Impact of Medical and Surgical Therapy in 200 Episodes

BACKGROUND Prosthetic joint infection in patients with rheumatoid arthritis is a serious complication of total joint arthroplasty. Little information is available on the outcome of medical and surgical treatments of prosthetic joint infection in patients with rheumatoid arthritis. METHODS We conducted a retrospective analysis of all patients with rheumatoid arthritis and a total hip or total knee arthroplasty infection evaluated at Mayo Clinic (Rochester, MN) between 1 January 1969 and 31 December 1995. RESULTS A total of 200 first episodes of prosthetic joint infection in 160 patients with rheumatoid arthritis were diagnosed during the study period. Thirty-seven percent of prosthetic joint infection episodes were due to Staphylococcus aureus. Of these episodes, 23% and 19% were treated with debridement and retention of components and 2-stage exchange, respectively. The type of surgical procedure was the only analyzed clinical variable that was associated with treatment failure (P < .001). Rates of 5-year survival free of treatment failure for patients with prosthetic joint infection episodes treated with debridement and retention of components, 2-stage exchange, and resection arthroplasty were 32% (95% confidence interval [CI], 21%-49%), 79% (95% CI, 66%-93%), and 61% (95% CI, 49%-74%), respectively. CONCLUSIONS S. aureus is the most common pathogen among patients with rheumatoid arthritis with prosthetic joint infection. Two-stage exchange was used in only 19% of the prosthetic joint infection episodes among patients with rheumatoid arthritis during the study period, but it was associated with the best outcome. The variable most strongly associated with the outcome was the type of surgical procedure.