Prior hip or knee prosthetic joint infection in another joint increases risk three-fold of prosthetic joint infection after primary total knee arthroplasty: a matched control study

AIMS

There is little information regarding the risk of a patient developing prosthetic joint infection (PJI) after primary total knee arthroplasty (TKA) when the patient has previously experienced PJI of a TKA or total hip arthroplasty (THA) in another joint. The goal of this study was to compare the risk of PJI of primary TKA in this patient population against matched controls.

PATIENTS AND METHODS

We retrospectively reviewed 95 patients (102 primary TKAs) treated between 2000 and 2014 with a history of PJI in another TKA or THA. A total of 50 patients (53%) were female. Mean age was 69 years (45 to 88) with a mean body mass index (BMI) of 36 kg/m² (22 to 59). In total, 27% of patients were on chronic antibiotic suppression. Mean follow-up was six years (2 to 16). We 1:3 matched these (for age, sex, BMI, and surgical year) to 306 primary TKAs performed in 306 patients with a THA or TKA of another joint without a subsequent PJI. Competing risk with death was used for statistical analysis. Multivariate analysis was followed to evaluate risk factors for PJI in the study cohort.

RESULTS

The cumulative incidence of PJI in the study cohort (6.1%) was significantly higher than the matched cohort (2.6%) at ten years (hazard ratio (HR) 3.3; 95% confidence interval 1.18 to 8.97; p = 0.02). Host grade in the study group was not a significant risk factor for PJI. Patients on chronic suppression had a higher rate of PJI (HR 15; p = 0.002), with six of the seven patients developing PJI in the study group being on chronic suppression. The new infecting microorganism was the same as the previous in only two of seven patients.

CONCLUSION

In this matched cohort study, patients undergoing a clean primary TKA with a history of TKA or THA PJI in another joint had a three-fold higher risk of PJI compared with matched controls with ten-year cumulative incidence of 6.1%. The risk of PJI was 15-fold higher in patients on chronic antibiotic suppression; further investigation into reasons for this and mitigation strategies are recommended. Cite this article: Bone Joint J 2019;101-B(7 Supple C):91-97.

2019 John Charnley Award: Increased risk of prosthetic joint infection following primary total knee and hip arthroplasty with the use of alternative antibiotics to cefazolin: the value of allergy testing for antibiotic prophylaxis

AIMS

The aims of this study were to characterize antibiotic choices for perioperative total knee arthroplasty (TKA) and total hip arthroplasty (THA) prophylaxis, assess antibiotic allergy testing efficacy, and determine rates of prosthetic joint infection (PJI) based on perioperative antibiotic regimen.

PATIENTS AND METHODS

We evaluated all patients undergoing primary TKA or THA at a single academic institution between January 2004 and May 2017, yielding 29 695 arthroplasties (22 705 patients), with 3411 arthroplasties in 2576 patients (11.5%) having undergone preoperative allergy testing. A series of institutional databases were combined to identify allergy consultation outcomes, perioperative antibiotic regimen, and infection-free survivorship until final follow-up.

RESULTS

Among 2576 allergy-tested patients, 2493 patients (97%) were cleared to use cephalosporins. For the entire cohort, 28 174 arthroplasties (94.9%) received cefazolin and 1521 (5.1%) received non-cefazolin antibiotics. Infection-free survivorship was significantly higher among arthroplasties receiving cefazolin compared with non-cefazolin antibiotics, with 0.06% higher survival free of infection at one month, 0.56% at two months, 0.61% at one year, and 1.19% at ten years (p < 0.001). Overall, the risk of PJI was 32% lower in patients treated with cefazolin after adjusting for the American Society of Anesthesiologists (ASA) classification, joint arthroplasty (TKA or THA), and body mass index (BMI; p < 0.001). The number needed to treat with cefazolin to prevent one PJI was 164 patients at one year and 84 patients at ten years. Therefore, potentially 6098 PJIs could be prevented by one year and 11 905 by ten years in a cohort of 1 000 000 primary TKA and THA patients.

CONCLUSION

PJI rates are significantly higher when non-cefazolin antibiotics are used for perioperative TKA and THA prophylaxis, highlighting the positive impact of preoperative antibiotic allergy testing to increase cefazolin usage. Given the low rate of true penicillin allergy positivity, and the readily modifiable risk factor that antibiotic choice provides, we recommend perioperative testing and clearance for all patients presenting with penicillin and cephalosporin allergies. Cite this article: Bone Joint J 2019;101-B(6 Supple B):9-15.

Seronegative infections in hip and knee arthroplasty

The aim of our study was to describe the characteristics, treatment, and outcomes of patients with periprosthetic joint infection (PJI) and normal inflammatory markers after total knee arthroplasty (TKA) and total hip arthroplasty (THA).

In total 538 TKAs and 414 THAs underwent surgical treatment for PJI and met the inclusion criteria. Pre-operative erythrocyte sedimentation rate (ESR) and C-reactive protein level (CRP) were reviewed to identify the seronegative cohort. An age- and gender-matched cohort was identified from the remaining patients for comparison. Overall, 4% of confirmed infections were seronegative (21 TKA and 17 THA). Of those who underwent pre-operative aspiration, cultures were positive in 76% of TKAs (n = 13) and 64% of THAs (n = 7). Cell count and differential were suggestive of infection in 85% of TKA (n = 11) and all THA aspirates (n = 5). The most common organism was coagulase-negative Staphylococcus. Seronegative infections were associated with a lower aspirate cell count and a lower incidence of Staphylococcus aureus infection. Two-stage revision was performed in 35 cases (95%). At a mean of five years (14 to 162 months) following revision, re-operation for infection occurred in two TKAs, and one THA. From our study we estimate around 4% of patients with PJI may present with normal ESR and CRP. When performed, pre-operative aspirate is useful in delivering a definitive diagnosis. When treated, similar outcomes can be obtained compared with patients with positive serology.

Cite this article: Bone Joint J 2015;97-B:939–44.

Efficacy and safety of rifampin containing regimen for staphylococcal prosthetic joint infections treated with debridement and retention

The aim of this study was to evaluate the efficacy and safety of rifampin for Staphylococcus aureus (SA) or coagulase negative staphylococci (CNS) prosthetic joint infection (PJI) treated with debridement and retention (D/R). We calculated the treatment failure cumulative incidence (TF) of a cohort of 101 patients with SA or CNS PJI treated with D/R and antimicrobial therapy. The effect of the use of a rifampin-based regimen was evaluated. Cox proportional hazards regression evaluated the association between treatment and time-to-TF controlling for the propensity to treat with rifampin and temporal confounders. Seven percent (1/14) of the prospective rifampin-treated patients, 32% (10/31) of the historical rifampin-treated patients and 38% (21/56) of the historical non-rifampin treated patients developed TF. After controlling for the propensity to treat with rifampin and American Society of Anesthesia scores, patients in the prospective cohort had a lower risk of TF compared to patients in the historical cohort not treated with rifampin (HR 0.11; 95%CI 0.01-0.84). None (0/14) of the patients in the prospective study developed hepatotoxicity. The outcome of staphylococcal PJI treated with D/R and rifampin-based regimens was better when compared with a historical cohort treated without rifampin.

Follow-up MR imaging in patients with pyogenic spine infections: lack of correlation with clinical features

BACKGROUND AND PURPOSE

Follow-up MR imaging examinations are increasingly used to monitor response to treatment in patients with spine infection. We aim to describe follow-up MR imaging examination findings 4-8 weeks after diagnosis and initiation of treatment of spine infections and to compare with clinical findings.

MATERIALS AND METHODS

Thirty-three patients with spinal infection and available baseline and 4-8-week follow-up MRIs were included in this retrospective cohort study. Baseline and follow-up MR imaging were graded by 2 neuroradiologists blinded to clinical characteristics and outcome. Clinical findings and outcomes were independently obtained by retrospective review of the medical record.

RESULTS

Compared with baseline MR imaging examinations, follow-up MR imaging more frequently demonstrated vertebral body loss of height (26/33 [79%] versus 14/33 [47%]; P < .001) and less frequently demonstrated epidural enhancement (19/32 [59%] versus 29/33 [88%]; P = .008), epidural canal abscess (3/32 [9%] versus 15/33 [45%]; P = .001), and epidural canal compromise (10/32 [31%] versus 19/33 [58%]; P = .008). Most follow-up MR imaging examinations demonstrated less paraspinal inflammation and less epidural enhancement compared with baseline. However, vertebral body enhancement, disk space enhancement, and bone marrow edema more often were equivocal or appeared worse compared with baseline. Twenty-one of 32 (66%) follow-up MR imaging examination overall grades were considered improved, 5 (16%) were equivocal, and 6 (19%) were worse. No single MR imaging finding was associated with clinical status.

CONCLUSION

Soft tissue findings, not bony findings, should be the focus of clinicians interpreting follow-up MR imaging results. No single MR imaging parameter was associated with the patients' clinical status.

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.

Prosthetic joint infection diagnosed postoperatively by intraoperative culture

The purpose of this study was to assess the outcome of prosthetic joint infection initially diagnosed by multiple positive intraoperative cultures after revision arthroplasty and treated by strategies that include less than 6 weeks of intravenous antimicrobial therapy. Between January 1995 and December 1999, 16 of 509 (3%) episodes of prosthetic joint infection in 16 patients initially were diagnosed by positive intraoperative cultures after revision arthroplasty. Patients were followed up for a median of 1057 days (range, 731-1969 days). The median age of the patients was 65 years, and 65% of patients had revision total hip arthroplasty. Coagulase-negative staphylococci and Propionibacterium spp were the main pathogens identified. Intravenous antimicrobial therapy was used in 81% of patients and chronic oral suppression was used in 56% of patients. Three patients received no antimicrobial therapy. The median duration of intravenous antimicrobial therapy was 28 days (range, 2-42 days). The 5-year survival free of treatment failure for the 16 episodes was 89%. These results suggest a favorable outcome of prosthetic joint infections because of low virulence pathogens initially diagnosed as positive intraoperative cultures after revision arthroplasty with a variety of medical treatment strategies, including strategies that contain less than 6 weeks intravenous antimicrobial therapy.

Outcome of penicillin-susceptible streptococcal prosthetic joint infection treated with debridement and retention of the prosthesis

Debridement with retention of the prosthesis was the initial treatment modality for 19 cases of penicillin-susceptible streptococcal prosthetic joint infection that occurred in 18 patients who presented to the Mayo Clinic (Rochester, Minnesota) during 1969-1998. All of the cases of prosthetic joint infection occurred >30 days after implantation of the prosthesis, which was well fixed at the time of debridement. The median duration of symptoms before debridement was 4 days (range, 1-10 days). Treatment failure (defined as relapse of infection with the original microorganism) occurred in 2 cases (10.5%) during a median follow-up period of 3.9 years (range, 0.3-21.7 years). The 1-year cumulative risk of relapse was 11% (95% confidence interval, 0%-26%). Relapse of prosthetic joint infection due to penicillin-susceptible streptococci after debridement and retention of the prosthesis is uncommon. For patients who present with a well-fixed prosthesis and a short duration of symptoms, debridement with retention appears to be an effective treatment modality.

Vertebral osteomyelitis and prosthetic joint infection due to Staphylococcus simulans

Staphylococcus simulans, a coagulase-negative staphylococcus, is a common animal pathogen that is rarely encountered in human infections. We describe a 70-year-old man who developed multifocal vertebral osteomyelitis and late prosthetic joint infection caused by this pathogen. The patient was a farmer who had daily contact with cows and drank unpasteurized milk, although the portal of the pathogen's entry remains speculative. Culture of the vertebral disk biopsy specimen and cultures during resection arthroplasty yielded S. simulans. A review of the literature suggests that S. simulans may be more virulent than other species of coagulase-negative staphylococci. Accurate identification of S. simulans isolates would facilitate studies to further define its pathogenic role in human infections.

Lack of effect of Lactobacillus GG on antibiotic-associated diarrhea: a randomized, placebo-controlled trial

OBJECTIVES

To assess the efficacy of Lactobacillus GG in preventing antibiotic-associated diarrhea (AAD) in adults and, secondarily, to assess the effect of coadministered Lactobacillus GG on the number of tests performed to determine the cause of diarrhea.

PATIENTS AND METHODS

In this prospective, randomized, double-blind, placebo-controlled trial conducted from July 1998 to October 1999, 302 hospitalized patients receiving antibiotics were randomized to receive Lactobacillus GG, 20 x 10(9) CFU/d, or placebo for 14 days. Subjects recorded the number of stools and their consistency daily for 21 days. The primary outcome was the proportion of patients who developed diarrhea in the first 21 days after enrollment. Weekly telephone follow-up was also performed. Results were analyzed in an intention-to-treat fashion.

RESULTS

Diarrhea developed in 39 (29.3%) of 133 patients randomized to receive Lactobacillus GG and in 40 (29.9%) of 134 patients randomized to receive placebo (P=.93). No additional difference in the rate of occurrence of diarrhea was found between treatment and placebo patients in a subgroup analysis of those treated with beta-lactam vs non-beta-lactam antibiotics. Too few patients had stool cultures, additional laboratory tests for diarrhea, or a positive diagnosis of Clostridium difficile infection to assess between-group differences.

CONCLUSION

Lactobacillus GG in a dose of 20 x 10(9) CFU/d did not reduce the rate of occurrence of diarrhea in this sample of 267 adult patients taking antibiotics initially administered in the hospital setting.

Fatal sepsis in a patient with rheumatoid arthritis treated with etanercept

Patients with long-standing, severe, erosive rheumatoid arthritis who have extra-articular manifestations and have undergone joint replacement surgery are at increased risk for serious infection and premature mortality. New therapies, including cytokine antagonists, hold great promise for improving the course of rheumatoid arthritis. However, they have powerful anti-inflammatory effects that may mask symptoms of serious infection. We report a case of fatal pneumococcal sepsis occurring in a 37-year-old woman with rheumatoid arthritis treated with the tumor necrosis factor antagonist etanercept and suggest management strategies for early detection and management of this complication.

Assessment of patient selection criteria for treatment of the infected hip arthroplasty

In a group of 37 infected hip arthroplasties (36 patients) treated consecutively between January 1997 and October 1999, the feasibility of published patient selection criteria for direct exchange arthroplasty was tested. These criteria include the requirement of a healthy patient with good soft tissues, minimal femoral bone loss, and an organism identified preoperatively as an antibiotic sensitive gram-positive organism. After assignment of the selection criteria, only four patients (four hips) (11%) were deemed potential candidates for a direct exchange procedure. Infected arthroplasties excluded from a primary exchange included 14 patients (15 hips) with gram-negative or methicillin-resistant gram-positive organisms obtained from preoperative joint aspirations, 10 patients (10 hips) with moderate or severe femoral bone loss, four patients (four hips) who required a proximal femoral osteotomy for component removal, two patients (two hips) with poor health status, and two patients (two hips) with poor soft tissues. Because of the increasing emergence of antibiotic-resistant bacteria and an increased prevalence of revision arthroplasties with associated bone loss, the feasibility of published selection criteria for direct exchange are limited. A philosophy of delayed reconstruction for the treatment of the infected hip arthroplasty seems most appropriate in the current era of patient treatment.

Reduction of vancomycin use in orthopedic patients with a history of antibiotic allergy

OBJECTIVE

To reduce prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery by using a targeted allergy consultation and penicillin allergy skin testing.

PATIENTS AND METHODS

The participants in this practice improvement study were patients with a history of penicillin or cephalosporin allergy who were scheduled for elective orthopedic surgery and referred by orthopedic surgeons for allergy consultation and penicillin allergy skin testing between September 22, 1998, and April 15, 1999. The primary outcome measure was the percentage of participants who received prophylactic cefazolin during the study period compared with historical controls.

RESULTS

Of the 60 study patients, 59 received a penicillin allergy skin test, 58 underwent orthopedic surgery, and 55 received antibiotic prophylaxis. Fifty-five patients had a history of allergy to penicillin, a cephalosporin, or both, and 5 had a history of nonspecific antibiotic allergy. Of the 59 patients, 55 (93%) had negative penicillin allergy skin test results. Fifty-four (90%) of the 60 patients were given clearance by the allergist to receive cefazolin. Of the 55 study patients who received antibiotic prophylaxis, 6 (11%) received vancomycin compared with 38 (30%) of 127 historical controls (P < or = .05). None of the study patients had an immediate reaction to cefazolin or to vancomycin.

CONCLUSION

Prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery can be reduced by a targeted allergy consultation and penicillin allergy skin testing.

Prosthetic joint infection due to Staphylococcus lugdunensis

Staphylococcus lugdunensis, a coagulase-negative staphylococcus, is being increasingly recognized as the cause of serious infections. We report 2 cases of total knee arthroplasty infection caused by S lugdunensis. S lugdunensis frequently produces a clumping factor that can result in a positive slide (short) coagulase test result. If the microbiology laboratory does not use the tube coagulase (long) test to confirm the slide coagulase test result, the organism may be misidentified as Staphylococcus aureus. S lugdunensis is more virulent than other coagulase-negative staphylococci and in many clinical situations behaves like S aureus, further increasing the confusion. However, S lugdunensis differs from S aureus in that it is susceptible to most antibiotics. This fact may alert the microbiology laboratory or the clinician that the isolate is likely not S aureus and prompt further testing of a specific isolate. Accurate identification of S lugdunensis isolates facilitates studies to define the epidemiology and pathogenesis of prosthetic joint infection due to S lugdunensis and delineates optimal medical and surgical therapies.

Antimicrobial prophylaxis in adults

Antimicrobial prophylaxis is used by clinicians for the prevention of numerous infections, including sexually transmitted diseases, human immunodeficiency virus infection, tuberculosis, rheumatic fever, recurrent cellulitis, meningococcal disease, recurrent uncomplicated urinary tract infections in women, spontaneous bacterial peritonitis in patients with cirrhosis, influenza, malaria, infective endocarditis, pertussis, plague, anthrax, early-onset group B streptococcal disease in neonates, and animal bite wounds. Certain opportunistic infections such as Pneumocystis carinii pneumonia in immunocompromised patients also can be effectively prevented with primary antimicrobial prophylaxis. Perioperative antimicrobial prophylaxis is recommended for various surgical procedures to prevent surgical site infection. Optimal antimicrobial agents for prophylaxis are bactericidal, nontoxic, inexpensive, and active against the typical pathogens that cause surgical site infection postoperatively. To maximize its effectiveness, intravenous perioperative prophylaxis should be given within 30 to 60 minutes before the time of surgical incision. Antibiotic prophylaxis should be of short duration to decrease toxicity, antimicrobial resistance, and excess cost.

The use of prophylactic antimicrobial agents during and after hip arthroplasty

An intravenous antibiotic, administered just before skin incision, effectively reduces the prevalence of deep wound infection. The optimal antimicrobial agent has not been determined definitively; however, a short duration of prophylaxis is recommended. Institutional compliance strategies are cost-effective and improve the timing of antibiotic administration. Also, published antimicrobial restriction recommendations are warranted because of the concern of emerging antibiotic-resistant bacteria. Specifically, restriction of vancomycin in orthopaedic surgery should be targeted critically. Supplemental antibiotic administration includes additional intra-operative antibiotic dosing, use of antibiotic-irrigant solutions, and admixture of antibiotics into acrylic bone cement or bone graft. There are no established standards or clinical guidelines for these supplemental antibiotic applications. Post-operatively, antimicrobial agents frequently are overused for various clinical scenarios and this pattern of antibiotic usage is potentially detrimental. A prophylaxis strategy for prevention of early and late hematogenous infection requires consideration of host risk factors, wound environment variables, and sources of potential bacteremia. This strategy should include deliberation of the cost-effectiveness, efficacy, and complications associated with routine use of antibiotics. Advisory statements for elective procedures, which potentially may cause bacteremia, are being developed and additional research is required for this area of antimicrobial agent prophylaxis.

Staphylococcus aureus prosthetic joint infection treated with prosthesis removal and delayed reimplantation arthroplasty

OBJECTIVE

To estimate in patients with Staphylococcus aureus prosthetic joint infection after total hip arthroplasty (THA) or total knee arthroplasty (TKA) the microorganism-specific cumulative probability of treatment failure after prosthesis removal and delayed reimplantation arthroplasty.

PATIENTS AND METHODS

All patients with S aureus THA or TKA infection, according to a strict case definition, who were treated with prosthesis removal and delayed reimplantation arthroplasty at Mayo Clinic Rochester between 1980 and 1991 were identified. The study group comprised patients who were free of infection at the time of reimplantation arthroplasty. This cohort was followed up until treatment failure, infection with another organism, prosthesis removal, death, or loss to follow-up occurred. The Kaplan-Meier survival method was used to estimate the cumulative probability of treatment failure.

RESULTS

Among 120 S aureus prosthetic joint infections treated with prosthesis removal during the study period, 38 episodes (22 THA, 16 TKA) in 36 patients met the study inclusion criteria. After a median of 7.4 years (range, 0.9 year-16.4 years) of follow-up, treatment failure occurred in 1 (2.6%) of 38 episodes 1.4 years after reimplantation arthroplasty. The 5-year cumulative probability of treatment failure was 2.8% (95% confidence interval, 0%-8.2%).

CONCLUSIONS

These data suggest that prosthesis removal and delayed reimplantation arthroplasty is an effective treatment to limit the recurrence of S aureus prosthetic joint infection, provided there is no evidence of infection at the time of reimplantation arthroplasty.

Risk factors for prosthetic joint infection: case-control study

We conducted a matched case-control study to determine risk factors for the development of prosthetic joint infection. Cases were patients with prosthetic hip or knee joint infection. Controls were patients who underwent total hip or knee arthroplasty and did not develop prosthetic joint infection. A multiple logistic regression model indicated that risk factors for prosthetic joint infection were the development of a surgical site infection not involving the prosthesis (odds ratio [OR], 35.9; 95% confidence interval [CI], 8.3-154.6), a National Nosocomial Infections Surveillance (NNIS) System surgical patient risk index score of 1 (OR, 1.7; 95% CI, 1.2-2.3) or 2 (OR, 3.9; 95% CI, 2.0-7.5), the presence of a malignancy (OR, 3.1; 95% CI, 1.3-7.2), and a history of joint arthroplasty (OR, 2.0; 95% CI, 1.4-3.0). Our findings suggest that a surgical site infection not involving the joint prosthesis, an NNIS System surgical patient risk index score of 1 or 2, the presence of a malignancy, and a history of a joint arthroplasty are associated with an increased risk of prosthetic joint infection.

Instructive case report. A 26-year-old Indian woman with seizures and multiple intracranial mass lesions

We describe the case of a 26-year-old Indian woman who presented to our institution with seizures and papilledema. Her diagnosis was originally thought to be neurocysticercosis, but later confirmed to be intracranial tuberculoma. Antituberculous therapy with isoniazid, rifampin, pyrazinamide and ethambutol was initiated. Improvement in the patient's neurological symptoms with diminution in size of the intracerebral lesions was observed. This case illustrates the difficulty in distinguishing intracranial tuberculoma from neurocysticercosis. Radiological features that distinguish these two diseases are described. Both diseases must be considered in regions endemic for tuberculosis and cysticercosis.

Treatment of infection with débridement and retention of the components following hip arthroplasty

Forty-two patients (forty-two hips) who had an infection following a hip arthroplasty were managed with open débridement, retention of the prosthetic components, and antibiotic therapy. After a mean duration of follow-up of 6.3 years (range, 0.14 to twenty-two years), only six patients (14 per cent) -- four of nineteen who had had an early postoperative infection and two of four who had had an acute hematogenous infection -- had been managed successfully. Of the remaining thirty-six patients, three (7 per cent of the entire group) were being managed with chronic suppression with oral administration of antibiotics and thirty-three (79 per cent of the entire group) had had a failure of treatment. All nineteen patients who had a late chronic infection were deemed to have had a failure of treatment. Débridement had been performed at a mean of six days (range, two to fourteen days) after the onset of symptoms in the patients who had been managed successfully and at a mean of twenty-three days (range, three to ninety-three days) in those for whom treatment had failed. Débridement with retention of the prosthesis is a potentially successful treatment for early postoperative infection or acute hematogenous infection, provided that it is performed in the first two weeks after the onset of symptoms and that the prosthesis previously had been functioning well. In our experience, this procedure has not been successful when it has been performed more than two weeks after the onset of symptoms. Retention of the prosthesis should not be attempted in patients who have a chronic infection at the site of a hip arthroplasty as this approach universally fails.

Metal-backed patellar component failure in total knee arthroplasty: a possible risk for late infection

Between 1985 and 1987, 1837 primary total knee arthroplasty (TKA) prostheses were implanted in 1503 patients. Group I included 843 knee with metal-backed patellar components (MBPC), and group II included 994 knees with all polyethylene patellar components (APPC). Follow-up averaged 5.7 years (range, 2 to 11 years). Twenty-four MBPC (2.9%) and 16 APPC TKA cases (1.6%) developed deep infection. In the time interval between arthroplasty and 2-year follow-up, eight MBPC and 11 APPC knees developed deep periprosthetic infection. The difference in the cumulative probability of infection between the two groups during this time interval was not significant (relative risk, 0.9; 95% confidence interval [CI], 0.3-2.1; P = 0.73). However, after the 2-year follow-up, 16 MBPC and 5 APPC knees developed late infection, and the difference in the cumulative probability of infection between the MBPC and APPC knees during this time interval was significant (relative risk, 3.1; 95% CI, 1.1-8.5; P = 0.02). Although the mechanism for this increased risk of these late infections is not well understood, the attendant synovitis, effusion, and relative hyperemia of these knees in the presence of the particulate metal and polyethylene debris may increase the potential of bacterial seeding to these prostheses. Particulate metal debris has been previously shown to suppress bacterial phagocytosis and may play a role in the pathogenesis of these infections. We propose that the presence of metal-backed patellar failure represents a "prosthesis at risk" for the development of late prosthetic infection.

Prosthetic joint infection due to Mycobacterium tuberculosis: a case series and review of the literature

Prosthetic joint replacement is being performed more frequently for patients with prior septic arthritis due to Mycobacterium tuberculosis. Prosthetic joint infection due to Mycobacterium tuberculosis does occur, but is rare. We report the clinical characteristics and outcome of seven cases of Mycobacterium tuberculosis prosthetic joint infection seen at our institution over a 22-year period and summarize the English-language literature regarding current prophylaxis and treatment strategies. Tuberculous prosthetic joint infection most often represents reactivation of prior tuberculous septic arthritis. The diagnosis of tuberculous prosthetic joint disease is often delayed, because a history of prior Mycobacterium tuberculosis septic arthritis is not known. Treatment of tuberculous prosthetic joint infection requires a combined medical and surgical approach. Removal of the prosthesis has been the traditional surgical modality, followed by appropriate antituberculous therapy, but other surgical methods have been used successfully in selected cases. To decrease the risk of reactivation of infection after prosthesis implantation in patients with quiescent tuberculous septic arthritis who have not received prior antituberculous therapy, consideration should be given to preoperative or perioperative antituberculous prophylaxis.

Laboratory diagnosis of central nervous system infections with herpes simplex virus by PCR performed with cerebrospinal fluid specimens

Until recently, the laboratory diagnosis of central nervous system (CNS) infections with herpes simplex virus (HSV) has been limited by poor sensitivity and/or specificity. We assessed the diagnostic utility of PCR for detection of HSV in over 2,100 specimens referred to the Mayo Clinic from August 1993 to May 1996. DNA extracted from cerebrospinal fluid (CSF) samples with IsoQuick was amplified by PCR with oligonucleotide primers directed to the DNA polymerase gene of HSV, yielding a 290-bp amplicon. HSV DNA was detected in 150 (135 by gel electrophoresis, 15 by Southern blotting only) of 2,106 (7.1%) specimens. PCR-positive CNS disease occurred in patients ranging in age from 13 days to 89 years; 59% of the cases occurred in patients between the ages of 30 and 69, and 21 (14%) of the patients were infants. Genotype analysis was not routinely performed; however, amplification of a 335-bp product within the thymidine kinase gene of HSV revealed 13 positions within a span of 80 nucleotides that accurately identified the two serotypes of the virus according to 14 reference strains. We conclude that PCR detection of HSV DNA in CSF specimens should be considered an emerging "gold standard" for the laboratory diagnosis of CNS infections with this virus.

Staphylococcus aureus prosthetic joint infection treated with debridement and prosthesis retention

Debridement and retention of the prosthesis was the initial treatment modality in 30 patients with 33 Staphylococcus aureus prosthetic joint infections (PJIs) who presented to the Mayo Clinic between 1980 and 1991. Treatment failure, defined as relapse of S. aureus PJI or occurrence of culture-negative PJI during continuous antistaphylococcal therapy, occurred in 21 of 33 prosthetic joints. The 1-year and 2-year cumulative probabilities of treatment failure were 54% (95% confidence interval [CI], 36%-71%) and 69% (95% CI, 52%-86%), respectively. A median of 4 additional surgical procedures (range, 1-9) were required to control the infection in the 21 prosthetic joints for which treatment failed. Prostheses that were debrided >2 days after onset of symptoms were associated with a higher probability of treatment failure than were those debrided within 2 days of onset (relative risk, 4.2; 95% CI, 1.6-10.3). These data suggest that debridement and retention of the prosthesis as the initial therapy for PJI due to S. aureus is associated with a high cumulative probability of treatment failure and that the probability of treatment failure may be related to the duration of symptoms.

Patient outcome with reinfection following reimplantation for the infected total knee arthroplasty

From 1976 to 1992, 24 knees (24 patients) were treated for reinfection after reimplantation of a prosthesis to treat an infected total knee arthroplasty. Including the index total knee arthroplasty, the average number of total procedures for the affected knee was 9.3 procedures (range, 5-23 procedures), and surgical procedures used for the affected knee after reinfection averaged 3.7 procedures (range, 1-12 procedures). The final outcome included 10 knees with a successful knee arthrodeses, 5 patients with infected prostheses who were prescribed suppressive oral antibiotic treatment, 4 above the knee amputations, 3 persistent pseudarthroses of the knee joint, 1 resection arthroplasty, and 1 uninfected total knee prosthesis. A poor prognosis was associated with use of a hinged knee design: 3 of the 4 amputations were done after a hinge knee prosthesis was implanted; 2 patients had a persistent pseudarthrosis after a failed attempt at knee arthrodesis; 1 patient had a resection arthroplasty; and 1 patient had a retained infected prosthesis. A successful arthrodesis in which the initial attempt included use of an external fixation devices was more likely for prostheses without stems (75%) when compared with cemented stemmed prostheses (40%). Long intramedullary arthrodesis was successful in all 3 attempts. Aspiration for diagnosis followed by oral antibiotic suppression was universally unsuccessful in 4 patients, whereas early aggressive open debridement facilitated retention of the prosthesis in 4 of 6 patients. The increased difficulty in achieving a healed wound, a successful knee arthrodesis, and eradication of infection with subsequent nonprosthetic salvage procedures as well as the attendant morbidity associated with reinfection must be considered carefully and discussed with the patient before the reimplantation prosthesis is inserted to treat the infected total knee arthroplasty.

Treatment of the infected total knee arthroplasty with insertion of another prosthesis. The effect of antibiotic-impregnated bone cement

Eighty-six patients with 89 infected total knee arthroplasties were treated with insertion of another prosthesis. Treatment was not according to an established protocol for parameters, such as delay between removal of the infected prosthesis and insertion of the new prosthesis, duration of antibiotics, use of antibiotic-impregnated cement spacers or beads, and use of antibiotic-impregnated cement for prosthetic fixation at revision surgery. Final followup averaged 52 months (range, 6-126 months). Complications occurred in 30 (33.7%) knees, with recurrent deep infection developing in 10 (11.24%) knees. Patient age, medical diagnosis, type of microorganism, duration of parenteral antibiotics, delay between the resection and revision surgery, and use of antibiotic-impregnated cement spacers or beads were not correlated with the cure rate of infection. Use of antibiotic-impregnated bone cement for prosthesis fixation at revision surgery was the only variable that correlated with the cure rate of deep infection. Seven (28%) of the 25 knees without antibiotic-impregnated cement for prosthesis fixation developed recurrent infection compared with 3 (4.7%) of 64 knees with antibiotic-impregnated cement for prosthesis fixation. This difference was statistically significant (p = 0.0025, log-rank test).

Prevention of deep wound infection after total hip arthroplasty: the role of prophylactic antibiotics and clean air technology

The role of antimicrobial prophylaxis has been established to be the single most significant factor in the prevention of deep wound infection following total hip arthroplasty. The proper dose, duration of treatment, and type of antibiotic have not been definitively established. The effect of clean air technology techniques has not been universally proven in the clinical setting to provide a reduction in the incidence of infection following total hip arthroplasty. The role of these two methods to prevent deep infection following total hip arthroplasty requires further study.

Lactobacillemia in liver transplant patients

Lactobacillemia is rare and, to our knowledge, previously undescribed in liver transplant patients. We reviewed the clinical records of all patients who had undergone orthotopic liver transplantation between January 1985 and August 1992 for whom a blood culture after transplantation yielded Lactobacillus species. A case-control study for determination of risk factors for lactobacillemia in this patient population was also performed. Eight cases of lactobacillus bacteremia were identified. All patients received nonabsorbable oral antibiotics for selective bowel decontamination. In addition, six of eight case patients received intravenous vancomycin prior to the development of lactobacillemia. The biliary anastomosis in each case patient was a Roux-en-Y choledochojejunostomy. Analysis of the case-control study revealed that the presence of a Roux-en-Y choledochojejunostomy at the time of lactobacillemia is a statistically significant risk factor (odds ratio [OR] = infinity, 95% confidence interval [CI] = 1.8-infinity, P < or = .05) but that prior administration of intravenous vancomycin is not a statistically significant risk factor (OR = 2.6, 95% CI = 0.38-30.0, P value not significant) for lactobacillemia. The use of selective bowel decontamination and of intravenous vancomycin in liver transplant patients may select for Lactobacillus species. Furthermore, a Roux-en-Y choledochojejunostomy may allow colonization of the intrahepatic biliary tract with enteric flora.

Relative efficacies of broad-spectrum cephalosporins for treatment of methicillin-susceptible Staphylococcus aureus experimental infective endocarditis

The effects of treatment with broad-spectrum parenterally administered cephalosporins and cefuroxime, cefazolin, or nafcillin were compared in an experimental model of Staphylococcus aureus infective endocarditis, and the results in vivo were compared with the activities of the study drugs in vitro. After 3 days of treatment, all antimicrobial agents tested were more effective than no treatment in reducing the number of surviving bacteria in cardiac valve vegetations. Nafcillin was the most effective agent studied and was significantly more active than was ceftizoxime, ceftriaxone, cefotaxime, cefoperazone, cefuroxime, or cefazolin (P < or = 0.05). Cefpirome and ceftazidime were the most effective broad-spectrum cephalosporins. The outcome of treatment with cefpirome or ceftazidime was similar to that of treatment with nafcillin and significantly better than that of treatment with ceftizoxime or cefotaxime (P < or = 0.05). Treatment outcome correlated closely with the MICs of the antimicrobial agents for the study strain with the exception of ceftazidime, which was significantly more active in vivo in comparison with other agents than predicted by its MIC (P < or = 0.0003). When ceftazidime was excluded as an outlier, treatment outcome correlated with the MICs of the remaining study drugs (Spearman's correlation coefficient, 0.95; P < or = 0.0004), as well as with the estimated percentage of time during which the concentration of total drug (correlation coefficient, -0.85; P < or = 0.007) or free drug (correlation coefficient, -0.90; P < or = 0.003) exceeded the MIC. A consideration of total or free drug concentrations in relation to MICs did not significantly improve the correlation with outcome observed with the MICs alone.

A prospective study of the polymerase chain reaction for detection of herpes simplex virus in cerebrospinal fluid submitted to the clinical virology laboratory

Polymerase chain reaction (PCR) was prospectively performed with cerebrospinal fluid (CSF) from 51 patients whose CSF was available for analysis and was submitted for viral culture and/or herpes simplex virus (HSV) serology and 20 patients whose CSF was submitted exclusively to the Clinical Biochemistry Laboratory. Primers were used that flanked a 92 bp segment of the HSV DNA polymerase gene (35 cycles). Amplified products were electrophoresed on agarose gel, blotted onto nylon membrane, and probed with a 32P-labelled sequence internal to the primers. For nested PCR, 1 microliter of PCR product was amplified for an additional 35 cycles before electrophoresis and Southern blot analysis. Review of the clinical records revealed that 15 patients had central nervous system (CNS) infections. Specific HSV DNA sequences were detected in CSF specimens of three of the individuals [PCR(2), nested PCR(1)]. Two of these patients had disseminated HSV infection including encephalitis and one patient had aseptic meningitis. The diagnoses of the 12 patients with CNS infection who did not have HSV DNA detected in CSF included encephalitis [varicella-zoster virus (1), cytomegalovirus (1), Mycoplasma pneumoniae (1)], meningitis [Neisseria meningitidis (1), Coccidioides immitis (1), Enterovirus (1), aseptic meningitis (1)], varicella-zoster radiculitis (2), human immunodeficiency virus dementia (2), and transverse myelitis due to Epstein-Barr virus (1). Importantly, HSV DNA was also not detected in the CSF of the 36 patients who did not have CNS infection and 20 samples submitted exclusively to the Clinical Biochemistry Laboratory. Our findings demonstrate the utility of PCR as a rapid, non-invasive method for the routine laboratory diagnosis of CNS infection due to HSV.

Successful orthotopic liver transplantation in a patient with refractory biliary candidiasis

The authors present a nonimmunocompromised patient who developed refractory fungal (Candida albicans) cholangitis and who subsequently underwent successful orthotopic liver transplantation for progressive destruction of intrahepatic and extrahepatic bile ducts. Liver biopsy specimens showed periductal abscesses, and cholangiograms showed rapidly progressive destruction of intrahepatic and extrahepatic bile ducts. Standard immunosuppressive therapy and perioperative amphotericin B were administered. At 6 months, the patient was clinically well with no evidence of recurrent biliary candidiasis. The authors suggest that orthotopic liver transplantation may be a reasonable therapeutic option for patients with refractory biliary candidiasis.

Viral hepatitis. A population-based study in Rochester, Minn, 1971-1980

The incidence of acute viral hepatitis among Rochester, Minn, residents 1971-1980 was 28.6 per 100,000 person-years (p-y) (age- and sex-adjusted to the 1980 white population in the United States). The adjusted incidence of hepatitis B (12.9 per 100,000 p-y) was somewhat less than for hepatitis non-B (15.6 per 100,000 p-y). Each type was more frequent among young adults, especially males. The incidence of hepatitis was greater among those employed in the health service industry than among nonmedical employees (53.4 vs 20.0 per 100,000 p-y). Medical employees had nearly a fivefold increased incidence of hepatitis B and a twofold increased incidence of hepatitis non-B. Exposure to known hepatitis cases was common, but other possible causative factors were not frequent. In this midwestern community, the incidence of acute viral hepatitis is substantial, with medical employees at significantly increased risk.