Healthcare-associated infective endocarditis: source of infection and burden of previous healthcare exposure

Objective

Prevention of healthcare-associated infective endocarditis (HAIE) is based on characterization of underlying factors. Our object was to describe the source of infection, microbiological etiology, and healthcare-related risk factors for HAIE.

Design

Retrospective population-based study.

Patients

Adult patients diagnosed with HAIE during 2013-2017 who resided in the study area in Southern Finland with adult population of 0.9 million.

Results

Ninety-five HAIE episodes were included. Ten episodes were related to cardiac surgery. Of the remaining 85 episodes, 11 were classified as nosocomial (ie, acquired and diagnosed during ongoing hospitalization) and 74 as non-nosocomial HAIE. Staphylococcus aureus caused 45% of nosocomial episodes, but only 16% of non-nosocomial episodes (P = 0.039). Most common sources of infection in non-nosocomial HAIE were previous hospitalization (24%), dialysis (18%), and urologic procedures (15%). Enterococcus spp. caused 23% of non-nosocomial HAIE, and more than half of them were associated with urologic or gastrointestinal procedures. Two-thirds of the non-nosocomial HAIE patients had recent hospitalization or invasive procedure. We counted previous healthcare-related risk factors for IE and those who had two or more of them had higher in-hospital and one-year mortality.

Conclusion

Our study indicates the importance of non-nosocomial acquisition of HAIE and S. aureus as the major pathogen in nosocomial episodes. Enterococcal infections dominate in non-nosocomial cases and further studies are needed to identify patients at risk for enterococcal IE after urological or gastrointestinal procedure.

Debridement, antimicrobials, and implant retention in the treatment of late acute and early acute Staphylococcus aureus prosthetic joint infections

BACKGROUND

Staphylococcus aureus is the most common microbe in prosthetic joint infections (PJIs). Debridement, antimicrobials, and implant retention (DAIR) are often-recommended treatment modality for acute PJIs, even though it has had relatively poor outcomes in some studies. In this study, we wanted to examine treatment results with a multidisciplinary team in a specialised centre and obtain further information for treatment decisions in acute Staphylococcus aureus PJIs.

METHODS

All consecutive haematogenous late acute and postoperative early acute hip and knee Staphylococcus aureus PJIs treated with DAIR during 2011-2016 were included in this retrospective study. DAIR within three weeks from symptom onset and the exchange of modular parts were required.

RESULTS

Eighty-five acute Staphylococcus aureus PJIs were treated with DAIR in 83 patients: 28 late acute and 57 early acute PJIs. The late acute PJI patients were older and had malignancies more often than the early acute PJI patients. Bacteraemia was present in 50.6% of Staphylococcus aureus PJI patients, more often in late acute (73.1%) than in early acute (40.4%) patients (p = .006). The implant was retained in 80.0%: 89.3% of the late acute and 75.4% of the early acute PJIs. In 17 joints, DAIR failed and the joint had to be removed. Fourteen of these joints were successfully replaced. One infection-related death occurred. The one-year all-cause mortality rate was 3.6%. Suppressive antimicrobial treatment was given to 22 (26.5%) patients.

CONCLUSIONS

Reasonably good treatment results for acute Staphylococcus aureus PJIs are achievable by DAIR in a specialised centre with a strict treatment protocol and a multidisciplinary team. If the DAIR fails, a two-stage exchange is usually still possible, with good results.

Case report and review: Angiosarcoma with thrombocytopenia after total hip arthroplasty

Total hip arthroplasty (THA) is a common treatment for osteoarthritis and is also performed for other conditions, such as secondary arthritis due to developmental dysplasia of the hip. Various THA types may be complicated by osteolysis and an inflammatory pseudotumor due to an adverse reaction to metal debris. Rarely, THA has been associated with malignant tumors, but their causality remains unclear. In this case report, we describe a female patient with developmental dysplasia of the hip. She had undergone left metal-on-polyethylene THA, acetabular revision of the THA, and left total knee arthroplasty. In addition, she had a history of dyslipidemia and telangiectasia of the eyes, anemia, hiatal hernia, and pleuritis. A THA-associated mass (suspected to be a pseudotumor) had been detected during a previous hospital admission due to pleuritis. She was hospitalized due to swelling in her left lower limb, fatigue, and bruises. A clinical examination revealed anemia, thrombocytopenia, and growth of the suspected pseudotumor. Within 6 weeks, she presented with bleeding of the oral mucosa, hemoptysis, melena, severe thrombocytopenia that did not respond to treatment, elevated D-dimer and C-reactive protein levels, severe pain, increased osteolysis, and fractures around the THA. Infection or malignancy was suspected, but two trocar biopsies suggested an inflammatory pseudotumor. Since her anemia and thrombocytopenia were considered to have been caused by an inflammatory process within the suspected pseudotumor, her suspected pseudotumor and all THA components were surgically removed. However, she developed severe alveolar hemorrhaging and hypoxia and died 2 weeks after her surgery. Histopathological analysis of her surgical and autopsy samples revealed highly malignant angiosarcoma. Although individual cases of malignancies associated with THA have been reported, the literature lacks a clear association between THA and increased cancer risk. Most pseudotumors are non-malignant. The patient's case presented in this report exemplifies the challenges to the differential diagnosis of a THA-associated pseudotumor and rare angiosarcoma. Atypically rapid tumor growth, severe osteolysis, and deterioration in the general wellbeing suggest a malignant disease.

Infectious complications after transrectal MRI-targeted and systematic prostate biopsy

PURPOSE

To compare infectious complications after transrectal systematic prostate biopsy (SB) and magnetic resonance imaging (MRI)-targeted biopsy (TB) in a large retrospective cohort to assess whether one technique is superior to the other regarding infectious complications.

METHODS

A total of 4497 patients underwent 5288 biopsies, 2875 (54%) SB and 2413 (46%) MRI-TB only. On average, 12 SB cores and 3.7 MRI-TB cores were taken per biopsy session during the study period. Infection-related complications within 30 days were compared. The primary endpoint was a positive urine culture. Secondary endpoints were positive blood cultures, urine tests with elevated leukocytes ≥ 100 E6/L and elevated C-reactive protein (CRP) ≥ 100 mg/L. Chi-square test was used to compare the cohorts.

RESULTS

Positive urine cultures were found in 77 (2.7%) after SB and in 42 (1.7%) after MRI-TB (p = 0.022). In total, 46 (0.9%) blood culture positive infections were found, 23 (0.9%) occurred after SB and 23 (1.0%) after MRI-TB, (p = 0.848). Urine tests with elevated leukocytes ≥ 100 E6/L were found in 111 (3.9%) after SB and in 61 (2.5%) after MRI-TB (p = 0.006). Elevated CRP ≥ 100 mg/L was found in 122 (4.2%) after SB and in 72 (3.0%) after MRI-TB (p = 0.015). Blood cultures were drawn more often after SB than after MRI-TB, but the difference was not statistically significant. However, urine cultures and CRP were taken more often after SB than MRI-TB.

CONCLUSION

Blood culture positive infections were equally rare after SB and MRI-TB. However, all other infectious complications were more common after SB than MRI-TB.

Effect of a multidisciplinary team on the treatment of hip and knee prosthetic joint infections: a single-centre study of 154 infections

BACKGROUND

A multidisciplinary team responsible for the management plan of prosthetic joint infections (PJI) was founded in January 2008. The aim of this study was to investigate whether a decrease in the number of surgeries and length of stay (LOS) was seen in the management of PJI with the aid of the multidisciplinary team.

METHODS

This retrospective cohort study consisted of a total of 154 postoperative PJIs from three time periods: 21 PJIs from 2005 to 2007 (Group 1), 65 PJIs from 2011 to 2013 (Group 2), and 68 PJIs from 2015 to 2016 (Group 3). Successful outcome was classified as the retention of the original implant or revised implant and no infection-related death.

RESULTS

The median number of operations decreased from 2.0 operations (Group 1) to 1.0 operation (Group 3) (p = .023), and the median LOS was shortened from 49.0 days (Group 1) to 17.0 days (Group 3) (p = .000). The number of PJIs treated with two-stage exchange decreased from 52.4% (11/21, Group 1) to 16.2% (11/68, Group 3) (p = .004). Simultaneously, debridement, antibiotics, and implant retention (DAIR) as primary surgical treatment increased from 42.9% (9/21, Group 1) to 89.7% (61/68, Group 3) (p = .000). The successful outcome of DAIR improved from 55.6% (5/9, Group 1) to 85.2% (52/61, Group 3) (p = .077).

CONCLUSIONS

Treatment of PJI in a specialized centre with the aid of a multidisciplinary team lead to fewer surgeries and reduced LOS. Successful outcome of DAIR improved over time.

Infections after intramedullary fixation of trochanteric fractures are uncommon and implant removal is not usually needed

BACKGROUND AND PURPOSE

Infections after intramedullary fixation of trochanteric femoral fractures are rare, but potentially life-threatening complications. There are limited data available to support decision making in these cases.

PATIENTS AND METHODS

A retrospective study of 995 consecutive operatively treated trochanteric fractures was made to find out different risk factors for infection and to describe the results of treatment.

RESULTS

28 patients developed a surgical site infection (2.8%) after intramedullary fixation of trochanteric fracture. 15 patients (1.5%) had a deep and 13 patients (1.3%) a superficial surgical site infection. Cigarette smoking (p<0.05) and prolonged operative time (p<0.05) were significant risk factors for an infection. 15 of 28 patients needed revision surgeries. Implant removal or exchange was needed only for 4 of 28 patients: 1 exchange of the blade, 1 removal of additional cable used to assist reduction and 2 removals of distal locking screws. None of the patients needed additional surgeries for problems with fracture healing. Mortality was not increased among patients with an infection.

INTERPRETATION

Infection after intramedullary fixation of trochanteric fractures can be successfully treated without removal or exchange of the fixation material.

Lower Success Rate of Débridement and Implant Retention in Late Acute versus Early Acute Periprosthetic Joint Infection Caused by Staphylococcus spp. Results from a Matched Cohort Study

BACKGROUND

Surgical débridement, antibiotics and implant retention (DAIR) is currently recommended by international guidelines for both early acute (postsurgical) and late acute (hematogenous) periprosthetic joint infections (PJIs). However, due to a different pathogenesis of infection, a different treatment strategy may be needed.

QUESTIONS/PURPOSES

(1) Compared with early acute PJIs, are late acute PJIs associated with a higher risk of DAIR failure? (2) When stratified by microorganism, is the higher risk of failure in late acute PJI associated with Staphylocococcus aureus infection? (3) When analyzing patients with S. aureus infection, what factors are independently associated with DAIR failure?

METHODS

In this multicenter observational study, early acute and late acute PJIs treated with DAIR were retrospectively evaluated and matched according to treating center, year of diagnosis, and infection-causing microorganism. If multiple matches were available, the early acute PJI diagnosed closest to the late acute PJI was selected. A total of 132 pairs were included. Treatment success was defined as a retained implant during follow-up without the need for antibiotic suppressive therapy.

RESULTS

Late acute PJIs had a lower treatment success (46% [60 of 132]) compared with early acute PJIs (76% [100 of 132]), OR 3.9 [95% CI 2.3 to 6.6]; p < 0.001), but the lower treatment success of late acute PJIs was only observed when caused by Staphylococcus spp (S. aureus: 34% versus 75%; p < 0.001; coagulase-negative staphylococci: 46% versus 88%; p = 0.013, respectively). On multivariable analysis, late acute PJI was the only independent factor associated with an unsuccessful DAIR when caused by S. aureus (OR 4.52 [95% CI 1.79 to 11.41]; p < 0.001).

CONCLUSIONS

Although DAIR seems to be a successful therapeutic strategy in the management of early acute PJI, its use in late acute PJI should be reconsidered when caused by Staphylococcus spp. Our results advocate the importance of isolating the causative microorganism before surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

High Cure Rate for Acute Streptococcal Prosthetic Joint Infections Treated With Debridement, Antimicrobials, and Implant Retention in a Specialized Tertiary Care Center

Streptococcal prosthetic joint infections (PJIs) treated with debridement, exchange of removable parts, antibiotics, and implant retention within 3 weeks from symptom onset had an implant survival rate of 97.9% and an implant survival rate without suppressive antimicrobials of 80.9%. Treatment centralization for acute streptococcal PJIs to specialized centers makes excellent cure rates possible.

Timing of implant-removal in late acute periprosthetic joint infection: A multicenter observational study

OBJECTIVES

We evaluated the treatment outcome in late acute (LA) periprosthetic joint infections (PJI) treated with debridement and implant retention (DAIR) versus implant removal.

METHODS

In a large multicenter study, LA PJIs of the hip and knee were retrospectively evaluated. Failure was defined as: PJI related death, prosthesis removal or the need for suppressive antibiotic therapy. LA PJI was defined as acute symptoms <3 weeks in patients more than 3 months after the index surgery and with a history of normal joint function.

RESULTS

445 patients were included, comprising 340 cases treated with DAIR and 105 cases treated with implant removal (19% one-stage revision (n = 20), 74.3% two-stage revision (n = 78) and 6.7% definitive implant removal (n = 7). Overall failure in patients treated with DAIR was 45.0% (153/340) compared to 24.8% (26/105) for implant removal (p < 0.001). Difference in failure rate remained after 1:1 propensity-score matching. A preoperative CRIME80-score ≥3 (OR 2.9), PJI caused by S. aureus (OR 1.8) and implant retention (OR 3.1) were independent predictors for failure in the multivariate analysis.

CONCLUSION

DAIR is a viable surgical treatment for most patients with LA PJI, but implant removal should be considered in a subset of patients, especially in those with a CRIME80-score ≥3.

A retrospective study on tolerability and complications of bacillus Calmette-Guérin (BCG) instillations for non-muscle-invasive bladder cancer

Objectives: The objective was to evaluate the tolerability of BCG treatment and to evaluate the effects of interruption on treatment outcomes. The incidence and characteristics of severe complications were observed. Methods: From hospital records, all bladder carcinoma patients treated with BCG instillations in the institution from 2009-2015 were retrospectively identified. The reasons for interruption, treatment outcome, number of instillations, and diagnosis of BCG infection were recorded. Results: Of the 418 patients who started BCG instillation therapy, 176 (42.1%) interrupted BCG treatment. Of those, 23 (5.5%) patients interrupted because of suspected BCG infection. Systemic BCG infection was found in seven (1.7%), and local infection in five (1.2%) patients. Interruption of treatment was due to other adverse effects in 71 patients (17.0%), BCG failure in 46 patients (11.0%), and other reasons in 36 patients (8.6%). Fifty percent of interruptions due to adverse effects occurred within the first 6 months. The probabilities of tumor recurrence (20.0% vs 10.7%, p = 0.014, OR = 2.077, CI_95% = 1.149-3.753) and disease progression (5.4% vs 1.2%, p = 0.018, OR = 4.534, CI_95% = 1.152-17.840) were higher among patients whose BCG treatment was interrupted. Conclusions: Severe complications were encountered in only <5% of patients. Adverse effects requiring treatment interruption were more likely to happen within the first year of treatment. Interrupting BCG treatment due to adverse effects increased the risk of disease progression and tumor recurrence.

Clinical outcome and risk factors for failure in late acute prosthetic joint infections treated with debridement and implant retention

OBJECTIVES

Debridement, antibiotics and implant retention (DAIR) is the recommended treatment for all acute prosthetic joint infections (PJI), but its efficacy in patients with late acute (LA) PJI is not well described.

METHODS

Patients diagnosed with LA PJI between 2005 and 2015 were retrospectively evaluated. LA PJI was defined as the development of acute symptoms (≤ 3 weeks) occurring ≥ 3 months after arthroplasty. Failure was defined as: (i) the need for implant removal, (ii) infection related death, (iii) the need for suppressive antibiotic therapy and/or (iv) relapse or reinfection during follow-up.

RESULTS

340 patients from 27 centers were included. The overall failure rate was 45.0% (153/340). Failure was dominated by Staphylococcus aureus PJI (54.7%, 76/139). Significant independent preoperative risk factors for failure according to the multivariate analysis were: fracture as indication for the prosthesis (odds ratio (OR) 5.4), rheumatoid arthritis (OR 5.1), age above 80 years (OR 2.6), male gender (OR 2.0) and C-reactive protein > 150 mg/L (OR 2.0). Exchanging the mobile components during DAIR was the strongest predictor for treatment success (OR 0.35).

CONCLUSION

LA PJIs have a high failure rate. Treatment strategies should be individualized according to patients' age, comorbidity, clinical presentation and microorganism causing the infection.

Incidence and risk factors for dental pathology in patients planned for elective total hip or knee arthroplasty

BACKGROUND AND AIMS

To prevent severe prosthetic joint infections, a dental examination is usually recommended prior to arthroplasty, even sometimes regarded resource- and time-consuming. The aim of this study was to determine whether a risk factor-based algorithm could be created to send only selected patients for dental clearance.

MATERIALS AND METHODS

A prospective study of 952 patients scheduled for elective arthroplasty was performed. Patients filled out a questionnaire regarding potential risk factors for dental infections, and dentists documented patients' oral health and interventions performed (data available for 731 patients).

RESULTS

Of the patients, 215 (29.4%) failed dental clearance; a total of 432 teeth were extracted, 32 patients (4.4%) required root canal treatment, and 37 patients (5.1%) had severe periodontitis. Independent risk factors for failure were history of root canal treatment (odds ratio: 2.282, 95% confidence interval: 1.346-3.869, p = 0.020), use of tobacco products (odds ratio: 1.704, 95% confidence interval: 1.033-2.810, p = 0.037), dental visit indicated by oral symptoms within 3 months (odds ratio: 1.828, 95% confidence interval: 1.183-2.827, p = 0.007), or visit to a dentist within 6 months (odds ratio: 1.538, 95% confidence interval: 1.063-2.224, p = 0.022). Regular dental examination was a preventive factor (odds ratio: 0.519, 95% confidence interval: 0.349-0.773, p = 0.001). However, based on the examined risk factors, no sufficiently large group of patients at lesser risk for dental infections could be identified.

CONCLUSION

Because of the high need for dental care revealed by our unselected patient population, the inspection and treatment of dental pathology of all patients are important interventions prior to elective arthroplasty.

The Not-So-Good Prognosis of Streptococcal Periprosthetic Joint Infection Managed by Implant Retention: The Results of a Large Multicenter Study

BACKGROUND.

Streptococci are not an infrequent cause of periprosthetic joint infection (PJI). Management by debridement, antibiotics, and implant retention (DAIR) is thought to produce a good prognosis, but little is known about the real likelihood of success.

METHODS.

A retrospective, observational, multicenter, international study was performed during 2003-2012. Eligible patients had a streptococcal PJI that was managed with DAIR. The primary endpoint was failure, defined as death related to infection, relapse/persistence of infection, or the need for salvage therapy.

RESULTS.

Overall, 462 cases were included (median age 72 years, 50% men). The most frequent species was Streptococcus agalactiae (34%), and 52% of all cases were hematogenous. Antibiotic treatment was primarily using β-lactams, and 37% of patients received rifampin. Outcomes were evaluable in 444 patients: failure occurred in 187 (42.1%; 95% confidence interval, 37.5%-46.7%) after a median of 62 days from debridement; patients without failure were followed up for a median of 802 days. Independent predictors (hazard ratios) of failure were rheumatoid arthritis (2.36), late post-surgical infection (2.20), and bacteremia (1.69). Independent predictors of success were exchange of removable components (0.60), early use of rifampin (0.98 per day of treatment within the first 30 days), and long treatments (≥21 days) with β-lactams, either as monotherapy (0.48) or in combination with rifampin (0.34).

CONCLUSIONS.

This is the largest series to our knowledge of streptococcal PJI managed by DAIR, showing a worse prognosis than previously reported. The beneficial effects of exchanging the removable components and of β-lactams are confirmed and maybe also a potential benefit from adding rifampin.

[Diagnosis and treatment of prosthetic hip and knee joint infections]

Successful replacement arthroplasty enhances the patient's functional capacity, alleviates pain and improves the quality of life. Prosthetic joint infection is one of the most dangerous complications following replacement arthroplasty. In cases of suspected prosthetic joint infection it is essential to consult with the prosthetic joint unit and abstain from starting antibiotics before the appropriate microbiological samples. The diagnosis is made on the basis of history, clinical picture, levels of inflammatory markers, synovial fluid cells and microbiological findings. The most common options of surgical treatment are early debridement and replacement of loose parts, and replacement of the prosthesis. Antimicrobial drug therapy will be planned according to the surgical mode of treatment and the causative bacterium.

The incidence of late prosthetic joint infections: a registry-based study of 112,708 primary hip and knee replacements

BACKGROUND AND PURPOSE

Late prosthetic joint infections (PJIs) are a growing medical challenge as more and more joint replacements are being performed and the expected lifespan of patients is increasing. We analyzed the incidence rate of late PJI and its temporal trends in a nationwide population.

PATIENTS AND METHODS

112,708 primary hip and knee replacements performed due to primary osteoarthritis (OA) between 1998 and 2009 were followed for a median time of 5 (1-13) years, using data from nationwide Finnish health registries. Late PJI was detected > 2 years postoperatively, and very late PJI was detected > 5 years postoperatively.

RESULTS

During the follow-up, involving 619,299 prosthesis-years, 1,345 PJIs were registered: cumulative incidence 1.20% (95% CI: 1.13-1.26) (for knees, 1.41%; for hips, 0.92%). The incidence rate of late PJI was 0.069% per prosthesis-year (CI: 0.061-0.078), and it was greater after knee replacement than after hip replacement (0.080% vs. 0.057%, p = 0.006). The incidence rate of very late PJI was 0.051% per prosthesis-year (CI: 0.042-0.063), 0.058% for knees and 0.044% for hips (p = 0.2). The incidence rate of late PJI varied between 0.041% and 0.107% during the years of observation without any temporal trend (incidence rate ratio (IRR) = 0.98, 95% CI: 0.93-1.03). Very late PJI increased from 0.026% in 2004 to 0.056% in 2010 (IRR = 1.11, 95% CI: 1.02-1.20).

INTERPRETATION

In our nationwide study, the incidence rate of late PJI after hip or knee arthroplasty was approximately 0.07% per prosthesis-year. The incidence of very late PJI appeared to increase.

Efficacy of a novel PCR- and microarray-based method in diagnosis of a prosthetic joint infection

BACKGROUND AND PURPOSE

Polymerase chain reaction (PCR) methods enable detection and species identification of many pathogens. We assessed the efficacy of a new PCR and microarray-based platform for detection of bacteria in prosthetic joint infections (PJIs).

METHODS

This prospective study involved 61 suspected PJIs in hip and knee prostheses and 20 negative controls. 142 samples were analyzed by Prove-it Bone and Joint assay. The laboratory staff conducting the Prove-it analysis were not aware of the results of microbiological culture and clinical findings. The results of the analysis were compared with diagnosis of PJIs defined according to the Musculoskeletal Infection Society (MSIS) criteria and with the results of microbiological culture.

RESULTS

38 of 61 suspected PJIs met the definition of PJI according to the MSIS criteria. Of the 38 patients, the PCR detected bacteria in 31 whereas bacterial culture was positive in 28 patients. 15 of the PJI patients were undergoing antimicrobial treatment as the samples for analysis were obtained. When antimicrobial treatment had lasted 4 days or more, PCR detected bacteria in 6 of the 9 patients, but positive cultures were noted in only 2 of the 9 patients. All PCR results for the controls were negative. Of the 61 suspected PJIs, there were false-positive PCR results in 6 cases.

INTERPRETATION

The Prove-it assay was helpful in PJI diagnostics during ongoing antimicrobial treatment. Without preceding treatment with antimicrobials, PCR and microarray-based assay did not appear to give any additional information over culture.

Risk factors for deep surgical site infection following operative treatment of ankle fractures

BACKGROUND

Surgical site infection is one of the most common complications following ankle fracture surgery. These infections are associated with substantial morbidity and lead to increased resource utilization. Identification of risk factors is crucial for developing strategies to prevent these complications.

METHODS

We performed an age and sex-matched case-control study to identify patient and surgery-related risk factors for deep surgical site infection following operative ankle fracture treatment. We identified 1923 ankle fracture operations performed in 1915 patients from 2006 through 2009. A total of 131 patients with deep infection were identified and compared with an equal number of uninfected control patients. Risk factors for infection were determined with use of conditional logistic regression analysis.

RESULTS

The incidence of deep infection was 6.8%. Univariate analysis showed diabetes (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.0, 4.9), alcohol abuse (OR = 3.8, 95% CI = 1.6, 9.4), fracture-dislocation (OR = 2.0, 95% CI = 1.2, 3.5), and soft-tissue injury (a Tscherne grade of ≥1) (OR = 2.6, 95% CI = 1.3, 5.3) to be significant patient-related risk factors for infection. Surgery-related risk factors were suboptimal timing of prophylactic antibiotics (OR = 1.9, 95% CI = 1.0, 3.4), difficulties encountered during surgery, (OR = 2.1, 95% CI = 1.1, 4.0), wound complications (OR = 4.8, 95% CI = 1.6, 14.0), and fracture malreduction (OR = 3.4, 95% CI = 1.3, 9.2). Independent risk factors for infection identified by multivariable analyses were tobacco use (OR = 3.7, 95% CI = 1.6, 8.5) and a duration of surgery of more than ninety minutes (OR = 2.5, 95% CI = 1.1, 5.7). Cast application in the operating room was independently associated with a decreased infection rate (OR = 0.4, 95% CI = 0.2, 0.8).

CONCLUSIONS

We identified several modifiable risk factors for deep surgical site infection following operative treatment of ankle fractures.

Obesity, diabetes, and preoperative hyperglycemia as predictors of periprosthetic joint infection: a single-center analysis of 7181 primary hip and knee replacements for osteoarthritis

BACKGROUND

Diabetes and obesity are common in patients undergoing joint replacement. Studies analyzing the effects of diabetes and obesity on the occurrence of periprosthetic joint infection have yielded contradictory results, and the combined effects of these conditions are not known.

METHODS

The one-year incidence of periprosthetic joint infections was analyzed in a single-center series of 7181 primary hip and knee replacements (unilateral and simultaneous bilateral) performed between 2002 and 2008 to treat osteoarthritis. The data regarding periprosthetic joint infection (defined according to Centers for Disease Control and Prevention criteria) were collected from the hospital infection register and were based on prospective, active surveillance. Patients diagnosed with diabetes were identified from the registers of the Social Insurance Institution of Finland. The odds ratios (ORs) for infection and the accompanying 95% confidence intervals (CIs) were calculated with use of binary logistic regression with adjustment for age, sex, American Society of Anesthesiologists risk score, arthroplasty site, body mass index, and diabetic status.

RESULTS

Fifty-two periprosthetic joint infections occurred during the first postoperative year (0.72%; 95% CI, 0.55% to 0.95%). The infection rate increased from 0.37% (95% CI, 0.15% to 0.96%) in patients with a normal body mass index to 4.66% (95% CI, 2.47% to 8.62%) in the morbidly obese group (adjusted OR, 6.4; 95% CI, 1.7 to 24.6). Diabetes more than doubled the periprosthetic joint infection risk independent of obesity (adjusted OR, 2.3; 95% CI, 1.1 to 4.7). The infection rate was highest in morbidly obese patients with diabetes; this group contained fifty-one patients and periprosthetic infection developed in five (9.8%; 95% CI, 4.26% to 20.98%). In patients without a diagnosis of diabetes at the time of the surgery, there was a trend toward a higher infection rate in association with a preoperative glucose level of ≥6.9 mmol/L (124 mg/dL) compared with &lt;6.9 mmol/L. The infection rate was 1.15% (95% CI, 0.56% to 2.35%) in the former group compared with 0.28% (95% CI, 0.15% to 0.53%) in the latter, and the adjusted OR was 3.3 (95% CI, 0.96 to 11.0). The type of diabetes medication was not associated with the infection rate.

CONCLUSIONS

Diabetes and morbid obesity increased the risk of periprosthetic joint infection following primary hip and knee replacement. The benefits of joint replacement should be carefully weighed against the incidence of postoperative infection, especially in morbidly obese patients.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Disease burden of prosthetic joint infections after hip and knee joint replacement in Finland during 1999-2004: capture-recapture estimation

We evaluated the Finnish Hospital Infection Program (SIRO) conducting incidence surveillance for prosthetic joint infection (PJI) from 1999 to 2004. We estimated its sensitivity using capture-recapture methods and assessed the disease burden of PJIs after hip (THA) and knee (TKA) arthroplasties (N = 13 482). The following three data sources were used: SIRO, the Finnish Arthroplasty Register (FAR), and the Finnish Patient Insurance Center (FPIC), which were cross-matched, and 129 individual PJIs were identified. After adjusting for the positive predictive value of SIRO (91%) a log-linear model including an interaction term between FAR and FPIC provided an estimated PJI rate of 1.6% [95% confidence interval (CI): 1.2-2.4] for THA and 1.3% (1.1-1.6) for TKA. Sensitivity for SIRO varied from 36% to 57%. The annual disease burden was 2.1 PJIs per 100 000 population after THA and 1.5 after TKA. The true disease burden of PJIs may be heavier than the rates from national sentinel surveillance systems usually suggest.

Low rate of infected knee replacements in a nationwide series--is it an underestimate?

BACKGROUND AND PURPOSE

Specialist hospitals have reported an incidence of early deep infections of < 1% following primary knee replacement. The purpose of this study was to estimate the infection rate in a nationwide series using register-based data.

METHODS

The Finnish Arthroplasty Register (FAR) was searched for primary unicompartmental, total, and revision knee arthroplasties performed in 1997 through 2003 and eventual revision arthroplasties. The FAR data on revision arthroplasties was supplemented by a search of the national Hospital Discharge Register (HDR) for debridements, partial and total revision knee replacements, resection arthroplasties, arthrodeses, and amputations.

RESULTS

During the first postoperative year, 0.33% (95% CI: 0.13-0.84), 0.52% (0.45-0.60) and 1.91% (1.40-2.61) of the primary UKAs, primary TKAs, and revision TKAs, respectively, were reoperated due to infection. The 1-year rate of reoperations due to infection remained constant in all arthroplasty groups over the observation period. The overall infection rate calculated using FAR data only was 0.77% (95% CI: 0.69-0.86), which was lower, but was not, however, statistically significantly different from the overall infection rate calculated using endpoint data combined from FAR and HDR records (0.89%; 95% CI: 0.80-0.99). FAR registered revision arthroplasties and patellar resurfacing arthroplasties reliably but missed a considerable proportion of other reoperations.

INTERPRETATION

More reoperations performed due to infection can be expected as the numbers of knee arthroplasties increase, since there has been no improvement in the early infection rate. Finnish Arthroplasty Register data appear to underestimate the incidence of reoperations performed due to infection.

Validation of surgical site infection surveillance in orthopedic procedures

BACKGROUND

Valid data are essential for a national surveillance system of nosocomial infections.

METHODS

In 8 hospitals conducting surgical site infection (SSI) surveillance for orthopedic procedures, a validation team performed a blinded retrospective chart review (10 operations with reported infections, 40 without) and interviewed infection control nurses.

RESULTS

In total, 397 patient charts were reviewed. Positive and negative predictive values for routine surveillance were 94% (95% CI: 89%-99%) and 99% (95% CI: 99%-100%), respectively. When these results were applied to the aggregated surveillance data (403 infections, 10,068 noninfections), sensitivity was 75% (95% CI: 56%-93%) and specificity 100% (95% CI: 97%-100%). The following case finding methods were used: ward visits (in 7/8 hospitals), microbiology reports (5/8), ward notifications by link nurses (8/8), and other nursing (7/8) and medical (5/8) staff. The wound culture rate ranged from 9 to 67 per 1000 patient-days. All hospitals carried out postdischarge surveillance on readmission and all but 1 at follow-up visits and by an additional questionnaire.

CONCLUSION

Most SSIs reported by the hospitals were true infections, showing that, when an SSI was reported, the definitions were correctly implemented. Some SSIs were missed, which might be due to weaknesses in case finding. Variation in diagnostic practices may also affect SSI rates.

Patient outcomes after simultaneous bilateral total hip and knee joint replacements

Simultaneous arthroplasties are increasingly being performed during one single anaesthetic event. No national nosocomial surveillance systems have yet reported data on this issue. We compared patient populations undergoing bi- and unilateral total hip (THA) and total knee (TKA) arthroplasties in terms of two outcome variables, deep surgical site infections (SSI) and mortality, by analysing surveillance data from the Finnish Hospital Infection Programme (SIRO). A total of 8201 patients underwent 9831 total arthroplasties during 2001-2004. Of the prosthetic joints, 7.2% were inserted in a bilateral operation (range by hospital, 0.6-19.2%; range by procedure type, 5.2-9.9%). Patients who underwent bilateral operations were younger; more often males, and their ASA score was lower than those who underwent unilateral procedures. The rate of deep SSI in bi- and unilateral THAs and in bi- and unilateral TKAs was 0, 0.5, 1.0 and 0.9%, respectively. Following bilateral operations, four deep SSIs were detected, all from bilateral TKAs, three of which were on the second operative side. In these three cases, single doses of antimicrobial prophylaxis were administered 115, 155 and 218 min before incision (median time in unilateral operations: 47 min). According to multi-variate analysis, bilateral operations were not an independent risk factor for deep SSIs. Mortality did not differ between bi- and unilateral THAs or TKAs. Our surveillance data indicate that simultaneous bilateral surgery did not increase the risk of deep SSIs or death after THA and TKA. Bilateral operations may, however, require specific guidelines regarding antimicrobial prophylaxis.

Impact of postdischarge surveillance on the rate of surgical site infection after orthopedic surgery

OBJECTIVE

To evaluate the impact of postdischarge surveillance on surgical site infection (SSI) rates after orthopedic surgery.

SETTING

Nine hospitals participating in the Finnish Hospital Infection Program.

PATIENTS

All patients who underwent hip or knee arthroplasty or open reduction of a femur fracture during 1999-2002.

RESULTS

The date of discharge was available for 11,812 procedures (90%). The median length of hospital stay was 8 days (range per hospital, 6-9 days). The overall SSI rate was 3.3% (range, 0.8%-6.4%). Of 384 SSIs detected, 216 (56%; range, 28%-90%) were detected after discharge: 93 (43%) were detected on readmission to the hospital, 73 (34%) at completion of a postdischarge questionnaire, and 23 (11%) at a follow-up visit. For 27 postdischarge SSIs (13%), the location of detection was unknown. Altogether, 32 (86%) of 37 of organ/space SSIs, 57 (80%) of 71 deep incisional SSIs, and 127 (46%) of 276 superficial incisional SSIs were detected after discharge. Most SSIs (70%) detected on readmission were severe (organ/space or deep incisional), whereas most SSIs (86%) detected at follow-up visits or at completion of a postdischarge questionnaire were superficial. Of all SSIs, 78% (range, 48%-100%) were microbiologically confirmed. Microbiologic confirmation was less common after discharge than during postoperative hospital stay (66% vs 93%; P<.001).

CONCLUSIONS

Postdischarge surveillance had a large impact on the rate of SSI detected after orthopedic surgery. However, postdischarge surveillance conducted by means of a questionnaire detected only a minority of deep incisional and organ/space SSIs.

Mediastinitis after more than 10,000 cardiac surgical procedures

BACKGROUND

Poststernotomy mediastinitis as a complication is rare but disastrous. We assessed incidence, predisposing factors for, and outcome from, mediastinitis after cardiac surgery.

METHODS

We studied 10,713 consecutive patients who underwent open-heart surgery from 1990 to 1999 in a tertiary care university hospital using data prospectively recorded in the hospital discharge register, operating room log, and the hospital's cardiothoracic surgery unit register. Those cases with possible mediastinitis were identified from the hospital infection register and discharge register. Patients' charts were reviewed and cases of mediastinitis confirmed based on criteria of the Centers for Disease Control and Prevention.

RESULTS

The overall rate of mediastinitis was 1.1% (120 cases), and higher in coronary artery bypass surgery than in valvular surgery (1.2 vs 0.8%). No trend in incidence was detectable, although surgical patients became progressively older (mean age, 59 to 65 years, p < 0.01), and the proportion of women (from 25% to 31%; p < 0.01) and of patients with American Society of Anesthesiologists score over 3 (from 10% to 81%, p < 0.01) both increased. The rate of mediastinitis was almost twice as high in men (1.2% vs 0.7%, p < 0.01). In three body mass index (BMI) categories (<25, 25 to 30, and >30 kg/m2), rates of mediastinitis were 0.5%, 1.0%, and 1.8%. In multivariate analysis adjusted for age, sex, year, operation type, and perfusion time, the only predictor for mediastinitis was BMI.

CONCLUSIONS

Mediastinitis is not diminishing. Larger populations at risk, for example proportions of overweight patients, reinforce the importance of surveillance and pose a challenge in focusing preventive measures.

Clinical manifestations and outcome in Staphylococcus aureus endocarditis among injection drug users and nonaddicts: a prospective study of 74 patients

BACKGROUND

Endocarditis is a common complication in Staphylococcus aureus bacteremia (SAB). We compared risk factors, clinical manifestations, and outcome in a large, prospective cohort of patients with S. aureus endocarditis in injection drug users (IDUs) and in nonaddicts.

METHODS

Four hundred and thirty consecutive adult patients with SAB were prospectively followed up for 3 months. Definite or possible endocarditis by modified Duke criteria was found in 74 patients: 20 patients were IDUs and 54 nonaddicts.

RESULTS

Endocarditis was more common in SAB among drug abusers (46%) than in nonaddicts (14%) (odds ratio [OR], 5.12; 95% confidence interval [CI], 2.65-9.91; P < 0.001). IDUs were significantly younger (27 +/- 15 vs 65 +/- 15 years, P < 0.001), had less ultimately or rapidly fatal underlying diseases (0% vs 37%, P < 0.001) or predisposing heart diseases (20% vs 50%, P = 0.03), and their SAB was more often community-acquired (95% vs 39%, P < 0.001). Right-sided endocarditis was observed in 60% of IDUs whereas 93% of nonaddicts had left-sided involvement (P < 0.001). An extracardiac deep infection was found in 85% of IDUs and in 89% of nonaddicts (P = 0.70). Arterial thromboembolic events and severe sepsis were also equally common in both groups. There was no difference in mortality between the groups at 7 days, but at 3 months it was lower among IDUs (10%) compared with nonaddicts (39%) (OR, 5.73; 95% CI, 1.20-27.25; P = 0.02).

CONCLUSION

S. aureus endocarditis in IDUs was associated with as high complication rates including extracardiac deep infections, thromboembolic events, or severe sepsis as in nonaddicts. Injection drug abuse in accordance with younger age and lack of underlying diseases were associated with lower mortality, but after adjusting by age and underlying diseases injection drug abuse was not significantly associated with mortality.

An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese

Background

Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak.

Methods

Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE).

Results

Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54–93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE.

Conclusion

The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.

Prevalence of low vitamin B12 and high homocysteine in serum in an elderly male population: association with atrophic gastritis and Helicobacter pylori infection

BACKGROUND

Deficiency of vitamin B12 raises the serum and tissue levels of homocysteine. Atrophic corpus gastritis results in impaired secretion of intrinsic factor and may lead to malabsorption of vitamin B12 in the intestine. We examined how common an undiagnosed vitamin B12 deficiency is among elderly men in the general population and, in particular, how often this deficiency is related to atrophic corpus gastritis.

METHODS

The serum level of pepsinogen I (S-PGI) was assayed in a population-based sample of 12,252 men (age 51-65 years) from two cities in Finland. In this sample, all 635 men with S-PGI < 25 microg/l formed Series A ('males with atrophic corpus gastritis'). Series C (controls--'males without atrophic corpus gastritis)' with a non-atrophic gastric corpus was formed as a random sample of men (n = 402) with S-PGI > or = 50 microg/l. Serum levels of vitamin B12 (S-B12), folate (S-Fol), total homocysteine (S-Hcy) and Helicobacter pylori antibodies (S-HpAb) were assayed in all, or in large subsamples, of the men in Series A and C. RESULTS The men in Series A had significantly lower S-B12 and S-Fol levels than those in Series C. In Series A, 172 of 613 men tested (28%) had S-B 12 < 170 pmol/ 1, and 133 men (22%) had S-B 12 in the range 170-219 pmol/l. The corresponding prevalences were 7% (P < 0.001) and 17% (P < 0.001) in Series C, respectively. The mean S-Hcy was significantly higher in Series A in men with low S-B12 than the mean S-Hcy in Series C in men with normal S-B12. The prevalence of S-Hcy > 15 ,micromol/l was 27% in Series A and 15% in Series C (P < 0.05; chi2 = 4.63). Among subjects with S-B 12 < 220 pmol/l, 46% (104 of 226 men tested) in Series A and 16% (16 of 99) in Series C had S-Hcy > or = 15 micromol/l (P < 0.001). The mean S-Hcy was significantly (P < 0.001) higher in men with S-B12 in the range 170-219 pmol/l in Series A (mean 14.6 +/- 5.0 micromol/l) than in Series C (11.3 +/- 3.0 micromol/l). It was extrapolated that 2.5% of men in the age group 51-65 years in the present study population had a low S-B12 (< 220 pmol/l) level that associated with atrophic corpus gastritis. Of these men, 72% (128 of 179 tested) had an elevated S-HpAb level.

CONCLUSIONS

Low S-B12 related to atrophic corpus gastritis is relatively common (prevalence 2.5%) among elderly males in the general population. An ongoing H. pylori infection occurs in three-fourths of these cases.

Incidence and risk factors for nosocomial infections caused by fluoroquinolone-resistant Escherichia coli

The aim of the retrospective case-control study presented here was to elucidate the incidence, risk factors, and outcomes of nosocomial infections caused by quinolone-resistant Escherichia coli (QREC). During the 3-year period studied, 51 nosocomial QREC infections were found, and the characteristics of these cases were compared with those of 102 control patients with quinolone-susceptible nosocomial infections. In the multivariate analysis, risk factors were identified as prior quinolone therapy (odds ratio [OR], 18.49; 95% confidence interval [CI], 5.53-61.82; P value <0.001), urinary tract abnormalities (OR, 6.69; 95% CI, 1.68-26.63; P=0.007), and prior therapy with other antimicrobial agents (OR, 3.57; 95% CI, 1.38-9.27; P=0.009). No difference in mortality or in length of hospital stay was found. Prudent use of quinolones, especially in patients with urinary tract abnormalities, is probably the best way to avoid an increase in the incidence of QREC infections, but further studies on interventions with restricted use of quinolones are necessary to demonstrate the effectiveness and safety of this strategy.

Lacrimal plugs as a therapy for contact lens intolerance

We investigated whether canalicular occlusion with a lacrimal plug could increase objective and/or subjective comfort in contact lens (CL) wearers (n = 9) with both a history of lens intolerance and relative tear fluid deficiency. A modified Schirmer test (MST) was performed with the lids closed and under topical anaesthesia. Patients with values of < or = 10 mm/5 min were included. The plugs were inserted into the inferior canaliculus of the eye with the lower MST result; the contralateral eye served as a control. Conjunctival hyperaemia, Rose-Bengal and fluorescein scores, as well as subjective irritation, decreased significantly in plugged eyes at the 1 month follow-up visit but had returned to the pre-operative level at the 3 month visit. Tear fluid plasmin activity was elevated prior to plug insertion. Plasmin activity of the plugged eye was significantly lower at the 1 month visit but neither tear fluid flow (in the collection capillary) nor plasmin release showed any changes. The mean MST value improved significantly, whereas conjunctival chemosis and limbal hyperaemia showed no improvement at the 1 or 3 month follow-up visits after inferior punctual occlusion. Occlusion of the lower canaliculus with a lacrimal plug seems to induce a relatively short-lasting subjective and objective benefit for CL wearers. Plug escape or adaptive changes in lacrimal fluid secretion/elimination rate probably took place during the follow-up. The association of increased plasmin activity with tear deficiency might lead to enhanced tissue proteolysis, and thus contribute to CL-related ocular surface changes.