Culture of Bone Biopsy Specimens Overestimates Rate of Residual Osteomyelitis After Toe or Forefoot Amputation.

BACKGROUND: Guidelines recommend both histological analysis and culture for definite diagnosis of osteomyelitis. It is not clear if histological and culture criteria can be used interchangeably in the clinical scenario of toe amputation. We therefore prospectively compared the results of intraoperative culture and those of histological examination in this setting. METHODS: Consecutive patients requiring toe or forefoot amputation at the University Hospital Basel during a 2-year period were included in the study. Biopsy specimens from the residual bone were cultured according to microbiological standards. Histological analysis was performed using standardized criteria for osteomyelitis. Clinical outcomes were assessed retrospectively via chart review. RESULTS: Of 51 patients included in the study, 33 (65%) had a positive culture of residual bone and 14 (27%) showed histological signs of osteomyelitis. A negative histological result but a positive culture was found for 21 (41%) of the patients, suggesting that culture has a high false-positive rate if histological analysis is used as the reference to rule out osteomyelitis. The recommended criteria of both positive histological findings and positive culture were fulfilled by 12 (24%) of the 51 patients. CONCLUSIONS: Positive cultures of residual bone after forefoot or toe amputation overestimate the true rate of osteomyelitis as defined by histological analysis, presumably because of contamination from soft tissue at the time of surgery. Additional studies are needed to evaluate the indications for, and the duration of, antibiotic treatment according to these findings. CLINICAL RELEVANCE: Our results cast doubt on the strategy of relying solely on culture of bone biopsy specimens when deciding whether antibiotic treatment for osteomyelitis is necessary after toe or forefoot amputation.

Temporal trends and epidemiology of Staphylococcus aureus surgical site infection in the Swiss surveillance network: a cohort study.

BACKGROUND: Staphylococcus aureus is the leading pathogen in surgical site infections (SSI). AIM: To explore trends and risk factors associated with S. aureus SSI. METHODS: Risk factors for monomicrobial S. aureus SSI were identified from the Swiss multi-centre SSI surveillance system using multi-variate logistic regression. Both in-hospital and postdischarge SSI were identified using standardized definitions. FINDINGS: Over a six-year period, data were collected on 229,765 surgical patients, of whom 499 (0.22%) developed monomicrobial S. aureus SSI; 459 (92.0%) and 40 (8.0%) were due to meticillin-susceptible S. aureus (MSSA) and meticillin-resistant S. aureus (MRSA), respectively. There was a significant decrease in the rate of MSSA SSI (P = 0.007), but not in the rate of MRSA SSI (P = 0.70). Independent protective factors for S. aureus SSI were older age [≥75 years vs <50 years: odds ratio (OR) 0.60, 95% confidence interval (CI) 0.44-0.83], laparoscopy/minimally invasive surgery (OR 0.68, 95% CI 0.50-0.92), non-clean surgery [OR 0.78 (per increase in wound contamination class), 95% CI 0.64-0.94] and correct timing of pre-operative antibiotic prophylaxis (OR 0.80, 95% CI 0.65-0.98). Independent risk factors were male sex (OR 1.38, 95% CI 1.14-1.66), higher American Society of Anesthesiologists' score (per one-point increment: OR 1.30, 95% CI 1.13-1.51), re-operation for non-infectious reasons (OR 4.59, 95% CI 3.59-5.87) and procedure type: cardiac surgery, laminectomy, and hip or knee arthroplasty had two-to nine-fold increased odds of S. aureus SSI compared with other procedures. CONCLUSIONS: SSI due to S. aureus are decreasing and becoming rare events in Switzerland. High-risk procedures that may benefit from specific preventive measures were identified. Unfortunately, many of the independent risk factors are not easily modifiable.

Secular trends of bloodstream infections during neutropenia in 15 181 haematopoietic stem cell transplants: 13-year results from a European multicentre surveillance study (ONKO-KISS).

OBJECTIVES: Antibacterial resistance is emerging in patients undergoing haematopoietic stem cell transplantation (HSCT), and most data on the epidemiology of bloodstream infections (BSI)-causing pathogens come from retrospective single-centre studies. This study sought to investigate trends in the epidemiology of BSI in HSCT patients from a prospective multicentre cohort. METHODS: We investigated changes in the incidence of causative organisms of BSI during neutropenia among adult HSCT patients for 2002-2014. The data were collected from a prospective cohort for infection surveillance in 20 haematologic cancer centres in Germany, Austria and Switzerland (ONKO-KISS). RESULTS: A total of 2388 of 15 181 HSCT patients with neutropenia (1471 allogeneic (61.6%) and 917 autologous (38.4%) HSCT) developed BSI (incidence 15.8% per year). The incidence of Gram-negative BSI increased over time both in patients after allogeneic HSCT (allo-HSCT) and autologous HSCT (auto-HSCT). BSI caused by Escherichia coli in allo-HSCT patients increased from 1.1% in 2002 to 3.8% in 2014 (3/279 vs. 31/810 patients, p <0.001), and the incidence of BSI caused by enterococci increased from 1.8% to 3.3% (5 vs. 27 patients, p <0.001). In contrast, the incidence of BSI due to coagulase-negative staphylococci decreased in allo-HSCT patients from 8.2% to 5.1%, (23 vs. 40 patients, p <0.001) and in auto-HSCT patients from 7.7% to 2.0% (13/167 vs. 30/540 patients; p = 0.028 for period 2002-2011). No significant trends were observed for the incidence of BSI due to methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci or extended-spectrum ß-lactamase-producing Enterobacteriaceae. The BSI case fatality remained unchanged over the study period (total of 477 fatalities, 3.1%). CONCLUSIONS: The incidence of Gram-negative BSI significantly increased over time in this vulnerable patient population, providing evidence for reevaluating empiric therapy for neutropenic fever in HSCT patients.

Validation of a treatment algorithm for orthopaedic implant-related infections with device-retention-results from a prospective observational cohort study.

Success rates for treatment regimens involving retention of an infected implant are conflicting and failure rates of up to 80% have been reported. We aimed to validate a proposed treatment algorithm, based on strict selection criteria, by assessing long-term outcome of treatment for orthopaedic device-related infection (ODRI) with retention. From January 1999 to December 2009, all patients diagnosed with ODRI at the University Hospital Basel, Switzerland were eligible for treatment with open surgical debridement, implant-retention and antibiotics, if duration of clinical symptoms was ≤3 weeks, the implant was stable, the soft-tissue had no abscess or sinus tract, and the causative pathogen was susceptible to antimicrobial agents with activity against surface-adhering microorganisms. Antimicrobial treatment was administered according to a predefined algorithm. The primary outcome was treatment failure after 2-year follow up. A total of 455 patients were diagnosed with an ODRI, of whom 233 (51.2%) patients were eligible for treatment involving implant-retention. Causative pathogens were mainly Staphylococcus aureus (41.6%) and coagulase-negative staphylococci (33.9%). Among patients with ODRIs related to prostheses, failure was documented in 10.8% (12/111) and in patients with ODRIs related to osteosyntheses, failure occurred in 9.8% (12/122) after 2 years of follow up. In all, 90% of ODRIs were successfully cured with surgical debridement and implant-retention in addition to long-term antimicrobial therapy according to a predefined treatment algorithm: if patients fulfilled strict selection criteria and there was susceptibility to rifampin for Gram-positive pathogens and ciprofloxacin for Gram-negative pathogens.

Is admission screening for Pseudomonas aeruginosa useful in haematologic patients? A prospective study with 1310 patients.

Screening for Pseudomonas aeruginosa is recommended to guide empirical antimicrobial therapy in patients on high-risk units. However, evidence for this approach is scarce. We therefore screened 1310 patients with severe haematologic diseases for P. aeruginosa colonization at admission: 108 (8.2%) were positive, but only nine (0.7%; six with the same clone as in the screening isolate) subsequently developed a P. aeruginosa bloodstream infection (positive predictive value of screening, 8.6%; negative predictive value of screening, 99.5%). Routine screening for P. aeruginosa at admission did not sufficiently predict subsequent bloodstream infections caused by P. aeruginosa.

Human metapneumovirus infection after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: The clinical characteristics of human metapneumovirus (hMPV)-associated lower respiratory tract infection (LRTI) after allogeneic hematopoietic stem cell transplantation (HSCT) is not well described. We describe the clinical course in eight HSCT recipients suffering from hMPV infection. METHODS: We prospectively included all patients with hMPV-associated LRTI after allogeneic HSCT during a period of 1 year. hMPV was diagnosed by multiplex polymerase chain reaction (PCR) from bronchoalveolar lavage (BAL). RESULTS: Eight patients with hMPV-associated LRTI were identified from 93 BAL samples. Three of the eight patients had co-infections with other pathogens. The median age of the patients was 45 years [interquartile range (IQR) 36.8-53.5], the median time posttransplant was 473 days (IQR 251-1,165), 5/8 patients had chronic graft-versus-host disease (cGvHD), and 6/8 patients received immunosuppression. Chest computed tomography (CT) scanning showed a ground-glass pattern in 7/8 patients. Seven of eight patients required hospitalization due to severe symptoms and hypoxemia. All were treated with intravenous immunoglobulin (IVIG), which was combined with oral ribavirin in six patients. The mortality rate was 12.5 % (1/8). CONCLUSIONS: hMPV-associated LRTI in allogeneic HSCT recipients are not uncommon and present with unspecific respiratory symptoms, ground-glass pattern in CT scanning, and co-infection.

Not all patients with vancomycin-resistant enterococci need to be isolated.

BACKGROUND: Vancomycin-resistant enterococci (VRE) have triggered multiple outbreaks. However, VRE of genotype vanC appear not to be associated with outbreaks. The goal of this study was to estimate the risk of bloodstream infections in patients colonized with VRE of genotype vanC who received care from a bone marrow transplant unit for patients with leukemia, where only standard precautions were implemented for VRE of genotype vanC during the last 9 years. METHODS: Since 2000, all patients in the bone marrow transplant unit underwent routine VRE rectal screening, data were prospectively entered in a database, and isolates were molecularly characterized. Infection control policy required contact isolation for patients infected with VRE of genotype vanA or vanB but only standard precautions for patients infected with VRE of genotype vanC. RESULTS: From January 2000 to July 2008, 290 isolates of VRE of genotype vanC obtained from 273 different patients were identified, with an incidence of 25-43 isolates/year. Of 290 isolates, 285 (98%) were identified in rectal screening swabs, 5 were from other body sites, and none required specific treatment. During the entire study period, only 1 case of bloodstream infection was detected, reflecting an incidence of 1 (0.4%) of the 273 patients, or <0.2 cases per 1000 patient-days. No outbreaks were recorded. CONCLUSIONS: These data provide strong evidence that carriers of VRE of genotype vanC do not require contact isolation, thereby saving resources and potentially improving patient care. The genotype should be routinely determined in areas with a high prevalence of VRE of genotype vanC.

Surveillance of surgical site infections by surgeons: biased underreporting or useful epidemiological data?

Surgical site infections (SSIs) significantly increase post-operative morbidity and mortality. SSI surveillance is an established monitoring tool and reduces SSI rates. The purpose of this study was to compare prospective in-hospital SSI surveillance (I) by the surgical staff and (II) additionally by an infection control team (ICT). The reference method (III) was defined by data generated by the surgical team, supplemented by the ICT and completed by post-discharge surveillance with a post-operative follow-up of one year representing the sum of all available resources. During 24 months, all consecutive inpatient procedures (N=6283) were prospectively recorded by the surgical staff until patients' discharge (I). SSI rates were compared with the surveillance performed by the ICT (II) and with the reference method (III). The overall SSI rate (reference method) was 4.7% (N=293), of which 187 (63.8%) were detected in-hospital and 106 (36.2%) after discharge. (I) The surgical staff detected 91/187 (48.7%) of in-hospital SSIs [91/293 (31.0%) of the reference], (II) the ICT an additional 96/187 (51.3%) during hospitalisation [96/293 (32.8%) of the reference]. Further cross-checking as performed in the visceral surgery department increased the surgeons' detection rate (I) to 59/105 (56.2%) of in-hospital SSIs [59/147 (40.1%) of the reference]. SSI surveillance by the surgical staff detects almost half of all in-hospital SSIs and has the potential to increase the detection rate by simple interventions such as cross-checking. Such a relatively inexpensive surveillance system is an option for hospitals without an ICT or for low risk surgical procedures. Moreover, trends in SSI rates can easily be detected, allowing early intervention.

[Postoperative wound infections: essentials for the internal medicine]. / Postoperative Wundinfektionen: Essenzielles für Internisten.

Surgical site infections are the most common nosocomial infections in surgical wards. The main risk factor is the comorbidity of patients. In addition, there are many preoperative and intraoperative factors that increase the risk of surgical site infections. Appropriate antimicrobial prophylaxis, adequate preparation of the patients by cessation of smoking and reducing weight are likely to prevent postoperative infections outside the operating theatre. The WHO has issued guidelines to prevent not only infectious, but also non-infectious complications after surgery. Surveillance of surgical site infections itself with adequate feedback to the surgeons decreases the rate by approximately 30%.

Surgical hand preparation: state-of-the-art.

Surgical hand preparation has been recommended since the nineteenth century as a measure to reduce infection resulting from surgery. We review the evidence and major objectives of surgical hand preparation, as well as the criteria for the choice of products currently in use. Test and validation procedures for selecting products for surgical hand preparation in North America and Europe are compared. Surgical hand antisepsis using medicated soap and alcohol-based hand-rub formulations is discussed, including the technical aspects, time required for the procedure, drying time, potential for side-effects, and the parameters for the selection of the most appropriate formulations. Brushes are not recommended for surgical hand preparation. Rapid antimicrobial action, wider spectrum of activity, lower side-effects, and the absence of the risk of hand contamination by the rinsing water, clearly favour the use of alcohol-based hand rubs for surgical hand preparation, even in countries with limited resources where the provision of water is scarce or of doubtful quality.

[Respiratory syncytial virus infections: measures in immunocompromised patients]. / Respiratorisches Syncytial-virus (RSV)-Infektion: Massnahmen beim immunsupprimierten Patienten.

RSV infections are an annually recurring problem of significant morbiditiy and mortality in the immunocompromised host, especially after lung and stem cell transplantation. The effectiveness of hygienic (isolation) and therapeutic (ribavirin, immunoglobulin, pavilizumab) measures depends of high index of suspicion and rapid diagnostic confirmation by the antigen test, PCR and/or culture. Allocation of resources require stratification of measures according to the known or estimated risk for complications.

Outbreaks of infectious diseases in stem cell transplant units: a silent cause of death for patients and transplant programmes.

Following the closure of the National Blood and Bone Marrow Transplant Unit in Dublin, because of an outbreak of vancomycin-resistant enterococcal infection, a survey was carried out by the EBMT to investigate the occurrence of outbreaks of infection in SCT units and the impact on patient morbidity, mortality and the administration of the transplant programme over a 10-year period from 1991 to 2001. A total of 13 centres reported 23 outbreaks of infection involving 231 patients: 10 bacterial, eight viral and five fungal outbreaks were reported and 56 deaths were attributed to infection. All fungal and bacterial deaths and the majority of viral deaths occurred in allograft recipients. In all outbreaks, the infection was reported to be hospital acquired and in all the viral, and half the bacterial infections, cross-infection was a major factor. All viral, four of 10 bacterial and three of five fungal outbreaks occurred in HEPA filtered rooms. A total of 12 SCT units reported a partial or total closure. The introduction of mandatory quality management systems such as JACIE should result in a change in attitude to 'incident reporting' and together with future surveys should reduce the incidence of infectious outbreaks in SCT units.

Gastroenteritis outbreak with norovirus in a Swiss university hospital with a newly identified virus strain.

We report an outbreak of norovirus-associated gastroenteritis in patients and healthcare workers (HCWs) at a university hospital in Switzerland during the period from 28 February to 31 March 2001. Faecal and vomitus specimens and bottled and drinking water were investigated for norovirus by reverse transcriptase-polymerase chain reaction (RT-PCR) Sixty-three patients and HCWs were affected. 37% of the investigated stool specimens were positive for norovirus. Sequencing showed a new phylogenetic strain, "Basel". There was no evidence for a water-borne, foodborne or environmental source. The source of the outbreak was most likely a patient admitted to the hospital. Once an outbreak was suspected, measures were instituted based on published guidelines, such as isolation of patients and excluding sick HCWs from work. However, the application of the guidelines proved difficult. A first realistic goal in such situations is to limit spread of the disease to other areas, specifically to high-risk areas such as intensive care and haemato-oncology units. Optimal management includes a rapid diagnosis of norovirus, written recommendations for management of affected patients and HCWs, and cleaning of surfaces with an effective disinfectant. These recommendations should be available in written form well before such an outbreak is in progress. Such preparations may limit the extent of the outbreak, but norovirus infection in a hospital will probably spread despite infection control interventions.

Safety of heart-lung machines during prolonged standby.

BACKGROUND: Coronary artery bypass surgery is increasingly performed without an extra-corporeal circuit. A heart-lung machine (HLM) is kept on standby for safety reasons, but rarely used. The tubes of the machines are currently discarded after every operation. Costs and waste would be avoided if HLMs could stay on standby for longer periods of time. We therefore investigated the sterility of intra-tube fluid over time. MATERIALS AND METHODS: Four machines were tested. The tube system was fixed and filled with priming solution. Samples of intra-tube fluid and fluid from the fluid bags were taken after 0, 12, 24, 36, 48 and 72 h. Microbiological cultures were performed by direct inoculation and membrane filtration and incubated up to 14 days. Endotoxin levels were also determined. RESULTS: Bacteria were grown from two samples only and were considered as contaminants. Endotoxin concentrations never exceeded acceptable levels. CONCLUSION: To keep HLMs on standby for 72 h is probably safe. The prolonged use of HLMs will contribute to cost and waste reduction in open heart surgery.

Serious bacterial infections in patients with rheumatoid arthritis under anti-TNF-alpha therapy.

OBJECTIVE: With rising numbers of anti-tumour necrosis factor alpha (TNF-alpha) treatments for rheumatoid arthritis (RA), Crohn's disease and other conditions, physicians unaware of potential pitfalls are increasingly likely to encounter associated severe infections. Our purpose was to assess the incidence and nature of severe infections in our RA patients under anti-TNF-alpha therapy. METHODS: We reviewed patient charts and records of the Infectious Disease Unit for serious infections in patients with RA in the 2 yr preceding anti-TNF-alpha therapy and during therapy. RESULTS: Serious infections affected 18.3% of patients treated with infliximab or etanercept. The incidence was 0.181 per anti-TNF-alpha treatment year vs 0.008 in the 2 yr preceding anti-TNF-alpha therapy. In several cases, only a few signs or symptoms indicated the severity of developing infections, including sepsis. CONCLUSIONS: A high level of suspicion of infection is necessary in patients under anti-TNF-alpha therapy. We suggest additional strategies for the prevention, rapid identification and pre-emptive therapy of such infections.

[Legionelloses]. / Legionellosen.

Legionnaire's disease is a life-threatening disease, observed in up to 15% of patients with pneumonia. Legionella pneumophila serogroup 1 is the most frequently implicated species among the genus Legionella. Legionella can cause two clinical pictures: Legionnaire's disease, a severe pneumonia, or Pontiac fever, a self-limiting disease. The attributable mortality of Legionnaire's disease is between 5-30%. Patients with typical Legionnaire's disease present with fever > 39 degrees C, cough and flu-like symptoms that do not respond to betalactam antibiotics. Neurological disorders may accompany severe cases. Laboratory findings include non-purulent sputum, increased liver enzymes and hyponatriemia. However, most patients do not fulfill all of these signs, symptoms and laboratory finding. Patients present with Legionella are frequently missed in the microbiology laboratory because clinicians do not ask for the specimen to be tested for Legionella. Established risk factors for Legionnaire's disease are chronic obstructive pulmonary disease (COPD), smoking and immunosuppressive therapy. New diagnostics tools such as the Legionella antigen in the urine, as well as PCR of a sputum sample allow rapid and accurate diagnosis. Such investigations are recommended for patients with severe pneumonia and those requiring hospitalization. State-of-the-art treatment includes a second generation macrolide, or alternatively, newer quinolones which are recommended as first-line drug for transplant patients. Prevention of Legionella requires a multi-faceted approach: The warm water should be kept at 60 degrees C in the boiler; the warm water should reach 50 degrees C at the faucet two minutes of opening the handle and the shower heads should be preferably made of stainless steel. In the hospital, the warm water supply should be free of Legionella at least for severely immunocompromised patients.

Cutaneous manifestations of Paecilomyces lilacinus infection induced by a contaminated skin lotion in patients who are severely immunosuppressed.

BACKGROUND: New opportunistic fungal infections cause significant morbidity and death in patients who are severely immunocompromised. Cutaneous lesions may be the first clinical manifestation and give the clue to early diagnosis. OBJECTIVE: The purpose of this study was to describe the clinical and histologic manifestations of Paecilomyces lilacinus infection in patients who are severely immunosuppressed. METHODS: Within a 3-month period, we observed 5 patients with allogenic bone marrow transplantation and 4 patients with aplasia after chemotherapy for hematologic malignancies who developed skin eruptions caused by invasive P lilacinus. RESULTS: The skin lesions began in 7 cases during or shortly after recovery of pancytopenia. Most of the skin lesions were located on the lower extremities. The cutaneous manifestations were highly variable including erythematous macules, nodules, pustules, vesicular lesions, and necrotic crusts. In 3 biopsy specimens, histologic examination revealed hyphae in periodic acid-Schiff-stained sections. In all patients P lilacinus was isolated from skin tissue samples. P lilacinus was identified from all lesions either by skin biopsy or needle aspiration from clinically evident lesions. In 3 additional cases, the patient's hands were colonized without skin lesions. The source of the epidemic outbreak was finally traced down to several contaminated lots of a topical moisturizing agent. Two patients died; one patient had septic lesions in the eye and kidney as the result of P lilacinus. CONCLUSION: Clinical and histologic findings of P lilacinus infection with cutaneous manifestations in patients who are severely immunosuppressed are summarized. P lilacinus is resistant to all systemic antimycotics available, and in general, recovery of immunosuppression is necessary to eradicate the mold. Contaminated topical dermatologic agents should be included in the differential diagnosis as a source for severe epidemic cutaneous manifestations of fungal infection in patients who are severely immunosuppressed. This fact implies that additional safety guidelines are necessary for topical dermatologic agents used for patients who are severely immunosuppressed.