Increasing SARS-CoV-2 testing capacity through specimen pooling: An acute care center experience.

Innovation in laboratory testing algorithms to address seemingly uncontrollable global supply chain shortages in plastics and other consumables during emergencies such as the current COVID-19 pandemic have been urgently needed. We report our experience with specimen pooling on SARS-CoV-2 testing in an acute care hospital microbiology laboratory during a high testing demand period that exceeded available processing capacity. A fully automated four-in-one pooling algorithm was designed and validated. Correlation and agreement were calculated. A custom Microsoft Excel tool was designed for use by the technologists to aid interpretation, verification and result entry. Cost-per-test impact for pooling was measured in reference to the consumable cost and was denoted as the percentage reduction of cost versus the baseline cost-per-test of testing specimens individually. Validation showed a strong correlation between the signals observed when testing specimens individually versus those that were pooled. Average crossing point difference was 1.352 cycles (95% confidence interval of -0.235 and 2.940). Overall agreement observed between individually and pooled tested specimens was 96.8%. Stratified agreement showed an expected decreased performance of pooling for weakly positive specimens dropping below 60% after a crossing point of 35. Post-implementation data showed the consumable cost-savings achieved through this algorithm was 85.5% after 8 months, creating both testing and resource capacity. Pooling is an effective method to be used for SARS-CoV-2 testing during the current pandemic to address resource shortages and provide quick turnaround times for high test volumes without compromising performance.

Auto-Substitutions to Optimize Perioperative Antimicrobial Prophylaxis: Pre-Post Intervention Study.

BACKGROUND: Appropriate administration of perioperative antibiotics can prevent antimicrobial resistance, adverse drug events, surgical site infections, and increased costs to the health care system for many surgeries in Otolaryngology-Head and Neck Surgery (OHNS). OBJECTIVE: The objective of the study is to achieve 90% compliance with evidence-based perioperative antibiotic prophylaxis guidelines among elective surgical procedures in OHNS. METHODS: The pre-intervention group consisted of patients undergoing elective surgical procedures in the 13 months prior to the interventions (September 2019-2020) whereas the post-intervention group comprised patients undergoing elective procedures during the 8 months following the implementation (October 2020-May 2021). The 4 Es of knowledge translation and the Donabedian framework were used to frame the study. Components of the intervention included educational grand rounds and automatic substitutions in electronic health records. In June 2021, a survey of staff and residents assessed the self-reported perception of following evidence-based guidelines. RESULTS: Compliance with antimicrobial prophylaxis guidelines were evaluated based on agent and dose. The overall compliance improved from 38.8% pre-intervention to 59.0% post-intervention (p < 0.001). Agent compliance did not improve from pre- to post-intervention, that is, 60.7% to 62.8%, respectively, (p = 0.68), whereas dose compliance improved from 39.6% to 89.2% (p < 0.001). Approximately 78.5% of survey respondents felt that they strongly agreed or agreed with always following evidence-based antimicrobial prophylaxis guidelines. CONCLUSION: Compliance with antimicrobial prophylaxis guidelines improved, primarily due to increased dosing compliance. Future interventions will target agent compliance and selected procedures with lower compliance rates. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:3403-3408, 2023.

Association of body mass index with COVID-19-related neurologic sequelae: a retrospective cohort study.

We sought to explore the relationship between body mass index (BMI) and neurologic outcomes following acute COVID-19 infection. We conducted a retrospective electronic medical record-based cohort study enrolling adults with laboratory-confirmed acute COVID-19 infection who presented to 1 of 12 academic and community hospitals in Southwestern Ontario, Canada between April 1, 2020 and July 31, 2021. Primary subjective (anosmia, dysgeusia, and/or headache) and objective (aseptic meningitis, ataxia, delirium, encephalopathy, encephalitis, intracranial hemorrhage, ischemic stroke, and/or seizure) composite neurologic outcomes were assessed, comparing obese and overweight individuals to those with underweight/normal BMI indices, adjusting for baseline characteristics. Secondary outcomes (severity of illness, length of hospital stay, SARS-CoV-2 viral load, mortality) were similarly analyzed. A total of 1437 enrolled individuals, of whom 307 (21%), 456 (32%), and 674 (47%) were underweight/normal, overweight, and obese, respectively. On multivariable analysis, there was no association between BMI category and the composite outcome for subjective (odds ratio [OR] 1.17, 95% CI 0.84-1.64, Bonferroni p = 1.00 for obese; OR 1.02, 95% CI 0.70-1.48; Bonferroni p = 1.00 for overweight) and objective (OR 0.74, 95% CI 0.42-1.30, p = 0.29 for obese; OR = 0.80, 95% CI 0.45-1.43, p = 0.45 for overweight) neurologic manifestations. There was no association between BMI category and any secondary outcome measure and no evidence of effect modification by age or sex. This study demonstrates the absence of an association between BMI and neurologic manifestations following acute COVID-19 illness. Prospective studies using standardized data collection tools and direct measures of body fat are warranted to obtain more valid effect estimates.

Monkeypox Virus Infections in Humans.

Human monkeypox is a viral zoonosis endemic to West and Central Africa that has recently generated increased interest and concern on a global scale as an emerging infectious disease threat in the midst of the slowly relenting COVID-2019 disease pandemic. The hallmark of infection is the development of a flu-like prodrome followed by the appearance of a smallpox-like exanthem. Precipitous person-to-person transmission of the virus among residents of 100 countries where it is nonendemic has motivated the immediate and widespread implementation of public health countermeasures. In this review, we discuss the origins and virology of monkeypox virus, its link with smallpox eradication, its record of causing outbreaks of human disease in regions where it is endemic in wildlife, its association with outbreaks in areas where it is nonendemic, the clinical manifestations of disease, laboratory diagnostic methods, case management, public health interventions, and future directions.

Clinical characteristics, multiorgan dysfunction and outcomes of patients with COVID-19: a prospective case series.

BACKGROUND: Characterizing the multiorgan manifestations and outcomes of patients hospitalized with COVID-19 will inform resource requirements to address the long-term burden of this disease. We conducted a descriptive analysis using prospectively collected data to describe the clinical characteristics and spectrum of organ dysfunction, and in-hospital and longer-term clinical outcomes of patients hospitalized with COVID-19 during the first wave of the pandemic at a Canadian centre. METHODS: We conducted a prospective case series involving adult patients (aged ≥ 18 yr) with COVID-19 admitted to 1 of 2 hospitals in London, Ontario, from Mar. 17 to June 18, 2020, during the first wave of the pandemic. We recorded patients' baseline characteristics, physiologic parameters, measures of organ function and therapies administered during hospitalization among patients in the intensive care unit (ICU) and in non-ICU settings, and compared the characteristics of hospital survivors and nonsurvivors. Finally, we recorded follow-up thoracic computed tomography (CT) and echocardiographic findings after hospital discharge. RESULTS: We enrolled 100 consecutive patients (47 women) hospitalized with COVID-19, including 32 patients who received ICU care and 68 who received treatment in non-ICU settings. Respiratory sequelae were common: 23.0% received high-flow oxygen by nasal cannula, 9.0% received noninvasive ventilation, 24.0% received invasive mechanical ventilation and 2.0% received venovenous extracorporeal membrane oxygenation. Overall, 9.0% of patients had cerebrovascular events (3.0% ischemic stroke, 6.0% intracranial hemorrhage), and 6.0% had pulmonary embolism. After discharge, 11 of 19 patients had persistent abnormalities on CT thorax, and 6 of 15 had persistent cardiac dysfunction on echocardiography. INTERPRETATION: This study provides further evidence that COVID-19 is a multisystem disease involving neurologic, cardiac and thrombotic dysfunction, without evidence of hepatic dysfunction. Patients have persistent organ dysfunction after hospital discharge, underscoring the need for research on long-term outcomes of COVID-19 survivors.

Evaluating the safety and effectiveness of a nurse-led outpatient virtual IV vancomycin monitoring clinic: a retrospective cohort study.

BACKGROUND: Outpatient parenteral antimicrobial therapy (OPAT) with vancomycin is a common treatment modality for certain Gram-positive infections. Data regarding the safety of various models of delivery are limited. OBJECTIVES: To review outcomes of a nurse-led OPAT vancomycin monitoring service. METHODS: This was a retrospective cohort study of consecutive patients referred to a nurse-led OPAT vancomycin clinic from December 2015 to March 2018. Patients were administered IV vancomycin in the home with active laboratory monitoring of vancomycin trough levels, renal function and complete blood count using an integrated electronic database linked with community laboratories (virtual vancomycin clinic, VVC). Monitoring was coordinated by nurses with physician approval of recommended dosing changes. Data were extracted from the electronic medical record. Demographics; clinical indication; microbial aetiology; culture source; antimicrobial regimen(s); serum creatinine and vancomycin trough values; initiation, discharge and completion dates; hospitalizations; adverse events; and outcomes were all evaluated. RESULTS: Two hundred and seventy-five patients underwent a total of 301 courses of OPAT with vancomycin; 285 courses were completed. The rate of treatment discontinuation due to adverse effects was 33/301 (11.0%), with 15/33 (45.5%) being due to renal adverse effects (15/301 [5.0%] of episodes). Two of 15 (18.2%) patients developed stage 2 acute kidney injury (AKI), and no patients had stage 3 AKI or required haemodialysis. Nine of 301 (3.0%) required readmission for treatment failure. Nursing costs associated with monitoring were $63.93 CAD/patient ($48.43 USD). CONCLUSIONS: A nurse-led VVC was a safe, effective and inexpensive modality for administering outpatient vancomycin.

A Murine Skin Infection Model Capable of Differentiating the Dermatopathology of Community-Associated MRSA Strain USA300 from Other MRSA Strains.

USA300 is a predominant and highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain that is a leading cause of skin and soft tissue infections. We established a murine intradermal infection model capable of demonstrating dermatopathological differences between USA300 and other MRSA strains. In this model, USA300 induced dermonecrosis, uniformly presenting as extensive open lesions with a histologically documented profound inflammatory cell infiltrate extending below the subcutis. In contrast, USA400 and a colonizing control strain M92 caused only localized non-ulcerated skin infections associated with a mild focal inflammatory infiltrate. It was also determined that the dermonecrosis induced by USA300 was associated with significantly increased neutrophil recruitment, inhibition of an antibacterial response, and increased production of cytokines/chemokines associated with disease severity. These results suggest that induction of severe skin lesions by USA300 is related to over-activation of neutrophils, inhibition of host antibacterial responses, and selective alteration of host cytokine/chemokine profiles.

Development of a provincial interactive antibiogram tool for Ontario.

Background: Antimicrobial resistance (AMR) is a public health issue with significant impact on health care. Antibiogram development and deployment is a key strategy for managing and preventing AMR. Our objective was to develop an Ontario antibiogram as part of a larger provincial initiative aimed at advancing antimicrobial stewardship in the province. Methods: As part of a voluntary provincial online survey, antibiogram data from 100 of 201 (49.8%) Ontario hospitals were collected and included. All hospitals in Ontario were eligible to participate except those providing only mental health or ambulatory services. Weighted provincial and regional antibiotic susceptibilities (percentages) were conducted using descriptive statistical analyses, and an interactive antibiogram spreadsheet was developed. Respondent-identified barriers to collecting and interpreting antibiogram data are presented descriptively. Results: There was wide regional variability in antimicrobial-resistant organisms across Ontario. Provincial methicillin-resistant Staphylococcus aureus prevalence was 24.6%, ranging from 5.9% to 43.7% regionally. Provincial Escherichia coli resistance to ceftriaxone and ciprofloxacin was 13.8% (regional range 6.0%-25.1%) and 22.5% (regional range 9.8-37.8%), respectively. Klebsiella spp resistance to ceftriaxone and ciprofloxacin was similar across all health regions, with overall provincial rates of 7.5% and 5.6%, respectively. Conclusions: We have demonstrated that integrating hospital AMR tracking and reporting as part of a larger voluntary provincial antimicrobial stewardship program initiative is a feasible approach to capturing AMR data. The provincial antibiogram serves as a benchmark for the current state of AMR provincially and across health regions.

Historique: La résistance antimicrobienne (RAM) est un enjeu sanitaire aux conséquences importantes sur les soins. La création et le déploiement d'antibiogrammes sont une stratégie essentielle pour gérer et prévenir la RAM. Les chercheurs s'étaient donné l'objectif de créer un antibiogramme ontarien dans le cadre d'une initiative provinciale plus vaste visant à faire progresser la gestion antimicrobienne dans la province. Méthodologie: Dans le cadre d'un sondage provincial volontaire en ligne, les chercheurs ont colligé et inclus les données d'antibiogrammes de 100 des 201 hôpitaux ontariens (49,8 %). Tous les hôpitaux de l'Ontario étaient admissibles à participer, sauf ceux qui ne donnaient que des services en santé mentale ou des services ambulatoires. Les chercheurs ont établi les susceptibilités antibiotiques provinciales et régionales pondérées (en pourcentage) d'après les analyses statistiques descriptives et ont créé un chiffrier interactif de l'antibiogramme. Ils ont fait une interprétation descriptive des obstacles indiqués par les participants à la collecte et à l'interprétation des données de l'antibiogramme. Résultats: La variabilité régionale des organismes résistants aux antimicrobiens est importante en Ontario. La prévalence de Staphylococcus aureus résistant à la méthicilline s'élevait à 24,6 %, et variait entre 5,9 % et 43,7 % selon les régions. La résistance provinciale de l'Escherichia coli à la ceftriaxone et à la ciprofloxacine correspondait à 13,8 % (plage régionale de 6,0 % à 25,1 %) et à 22,5 % (plage régionale de 9,8 % à 37,8 %), respectivement. La résistance des espèces de Klebsiella à la ceftriaxone et à la ciprofloxacine était semblable dans toutes les régions sanitaires, les taux provinciaux globaux s'établissant à 7,5 % et 5,6 %, respectivement. Conclusion: Les auteurs ont démontré que l'intégration d'une fonction de traçage et de déclaration de la RAM aux hôpitaux dans le cadre d'un plus vaste programme provincial de gestion antimicrobienne volontaire est une démarche faisable pour saisir les données de RAM. L'antibiogramme provincial sert de référence pour obtenir un portrait à jour de la RAM dans la province et les régions sanitaires.

Human Case of Streptococcus suis Disease, Ontario, Canada.

We report a case of Streptococcus suis human disease in Ontario, Canada, caused by a serotype 2 strain genotypically similar to those commonly isolated from pigs in North America. Initially, the isolate was misidentified as a viridans group Streptococcus. Human S. suis infections may be underdiagnosed in North America.

Treatment of asymptomatic UTI in older delirious medical in-patients: A prospective cohort study.

BACKGROUND: Despite clinical practice guidelines, asymptomatic bacteriuria (ASB) in older people is frequently treated. A common reason for treating ASB is a change in mental status. OBJECTIVE: To determine how often asymptomatic UTI is treated in older medically ill delirious individuals and its association with functional recovery. METHODS: Consecutive older medical in-patients were screened for delirium, and followed in hospital. Treatment for asymptomatic UTI was defined as documented treatment for a possible urinary tract infection with antibiotics, without concurrent infectious or urinary symptoms. The primary outcome was functional recovery at discharge or 3 months post-discharge. Poor functional recovery was defined by any one of death, new permanent long-term institutionalization or decreased ability to perform activities of daily living. RESULTS: The study sample comprised 343 delirious in-patients, of which 237 (69%) had poor functional recovery. Ninety two (27%) delirious in-patients were treated for asymptomatic UTI. Treatment for asymptomatic UTI was associated with poor functional recovery compared to other delirious in-patients (RR 1.30, 95% CI: 1.14-1.48 overall). Similar results were seen when the analysis was restricted to only bacteriuric delirious individuals. Seven (7.5%) individuals treated for asymptomatic UTI developed Clostridium difficile infection compared to eight (3.2%) in the remainder of the delirious cohort (OR 2.45, 95% CI: 0.86-6.96). CONCLUSIONS: These results suggest that treatment of asymptomatic UTI in older medical in-patients with delirium is common, and of questionable benefit. Further research is needed to establish guidelines to minimize over-treatment of UTI in older delirious in-patients.

Infectious diseases specialist management improves outcomes for outpatients diagnosed with cellulitis in the emergency department: a double cohort study.

Three hospital emergency rooms (ERs) routinely referred all cases of cellulitis requiring outpatient intravenous antibiotics, to a central ER-staffed cellulitis clinic. We performed a retrospective cohort study of all patients seen by the ER clinic in the last 4months preceding a policy change (ER management cohort [ERMC]) (n=149) and all those seen in the first 3months of a new policy of automatic referral to an infectious disease (ID) specialist-supervised cellulitis clinic (ID management cohort [IDMC]) (n=136). Fifty-four (40%) of 136 patients in the IDMC were given an alternative diagnosis (noncellulitis), compared to 16 (11%) of 149 in the ERMC (P<0.0001). Logistic regression-demonstrated rates of disease recurrence were lower in the IDMC than the ERMC (hazard ratio [HR], 0.06; P=0.003), as were rates of hospitalization (HR, 0.11; P=0.01). There was no significant difference in mortality. Automatic ID consultation for cellulitis was beneficial in differentiating mimickers from true cellulitis, reducing recurrence, and preventing hospital admissions.

Staphylococcus pettenkoferi bacteremia: A case report and review of the literature.

Staphylococcus pettenkoferi is a relatively recently described coagulase-negative staphylococci species first described in 2002. Since then, nine additional cases of infection caused by this species have been reported in various countries around the world, including Germany, Belgium, France, South Korea, Italy, Brazil and Mexico. The present report describes a case of S pettenkoferi peripheral line-associated bacteremia. To our knowledge, the present report is the first description of human infection caused by S pettenkoferi in Canada. The present report also provides an overview of the laboratory detection of uncommon coagulase-negative staphylococci.

Le Staphylococcus pettenkoferi est une espèce de staphylocoque à coagulase négative qui a été décrit pour la première fois en 2002. Depuis, neuf autres cas d'infections causées par cette espèce ont été signalés dans divers pays du monde, y compris l'Allemagne, la Belgique, la France, la Corée du Sud, l'Italie, le Brésil et le Mexique. Le présent rapport décrit un cas de bactériémie à S pettenkoferi associée à un cathéter périphérique. En autant que les auteurs le sachent, il s'agit du premier rapport d'infection humaine à S pettenkoferi au Canada, qui donne également un aperçu de la détection en laboratoire de staphylocoques à coagulase négative rares.

Community-associated methicillin-resistant Staphylococcus aureus necrotizing pneumonia without evidence of antecedent viral upper respiratory infection.

BACKGROUND: USA300 community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) strains causing necrotizing pneumonia have been reported in association with antecedent viral upper respiratory tract infections (URI). METHODS: A case series of necrotizing pneumonia presenting as a primary or coprimary infection, secondary to CA-MRSA without evidence of antecedent viral URI, is presented. Cases were identified through the infectious diseases consultation service records. Clinical and radiographic data were collected by chart review and electronic records. MRSA strains were isolated from sputum, bronchoalveolar lavage, pleural fluid or blood cultures and confirmed using standard laboratory procedures. MRSA strains were characterized by susceptibility testing, pulsed-field gel electrophoresis, spa typing, agr typing and multilocus sequence typing. Testing for respiratory viruses was performed by appropriate serological testing of banked sera, or nucleic acid testing of nasopharyngeal or bronchoalveloar lavage specimens. RESULTS: Ten patients who presented or copresented with CA necrotizing pneumonia secondary to CA-MRSA from April 2004 to October 2011 were identified. The median length of stay was 22.5 days. Mortality was 20.0%. Classical risk factors for CA-MRSA were identified in seven of 10 (70.0%) cases. Chest tube placement occurred in seven of 10 patients with empyema. None of the patients had historical evidence of antecedent URI. In eight of 10 patients, serological or nucleic acid testing testing revealed no evidence of acute viral coinfection. Eight strains were CMRSA-10 (USA300). The remaining two strains were a USA300 genetically related strain and a USA1100 strain. CONCLUSION: Pneumonia secondary to CA-MRSA can occur in the absence of an antecedent URI. Infections due to CA-MRSA are associated with significant morbidity and mortality. Clinicians need to have an awareness of this clinical entity, particularly in patients who are in risk groups that predispose to exposure to this bacterium.

HISTORIQUE: Des souches USA300 de Staphylococcus aureus résistant à la méthicilline (SARM) d'origine non nosocomiale (ONN) responsables d'une pneumonie nécrosante ont été signalées après des infections des voies respiratoires supérieures. MÉTHODOLOGIE: Les chercheurs présentent une série de cas de pneumonie nécrosante se manifestant sous forme d'infection ou de co-infection primaire découlant du SARM-ONN, sans manifestation d'IVRS virale antérieure. Ils ont dépisté les cas en dépouillant les dossiers des services de consultation en infectiologie. Ils ont colligé les données cliniques et radiographiques en analysant les dossiers papier et électroniques. Les souches de SARM avaient été isolées dans les expectorations, le lavage broncho-alvéolaire, le liquide pleural ou les hémo-cultures et confirmées au moyen d'analyses de laboratoire standards. Les souches de SARM étaient caractérisées par les tests de susceptibilité, l'électrophorèse sur gel en champ pulsé, le typage du gène spa ou du gène agr ou le typage génomique multilocus. Les tests de dépistage des virus respiratoires ont été faits au moyen du test sérologique pertinent du sérum en réserve ou du test d'amplification des acides nucléiques des échantillons de lavage nasopharyngé ou broncho-alvéolaire. RÉSULTATS: Entre avril 2004 et octobre 2011, les chercheurs ont dépisté dix patients qui présentaient, seule ou conjointement, une pneumonie nécrosante d'ONN secondaire à une infection par le SARM-ONN. Ils ont été hospitalisés pendant une période médiane de 22,5 jours. Le taux de mortalité s'élevait à 20,0 %. Les chercheurs ont constaté des facteurs de risque classiques de SARM-ONN dans sept des dix cas (70,0 %). Sept des dix patients faisant de l'empyème avaient eu un drain thoracique. Aucun des patients n'avait d'antécédents démontrés d'IVRS. Chez huit des dix patients, le test sérologique et le test d'amplification des acides nucléiques n'ont révélé aucune manifestation de co-infection virale aiguë. Huit souches étaient des SARMC-10 (USA300). Les deux autres étaient une souche liée génétiquement au USA300 et une souche USA1100. CONCLUSION: La pneumonie secondaire au SARM-ONN peut se manifester en l'absence d'IVRS antérieure. Les infections causées par le SARM-ONN s'associent à une morbidité et une mortalité importantes. Les cliniciens doivent connaître cette entité clinique, notamment chez les patients qui font partie de groupes vulnérables qui les prédisposent à être exposés à cette bactérie.

Characterization of methicillin-resistant Staphylococcus aureus isolates from patients with persistent or recurrent bacteremia.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with considerable morbidity and mortality, especially with persistent (PB) or recurrent bacteremia (RB). OBJECTIVE: To determine the frequency of PB and RB in patients with MRSA BSI, and to characterize the isolates from these patients. METHODS: Surveillance for MRSA BSI was performed for one year in 13 Canadian hospitals. PB was defined as a positive blood culture that persisted for ≥7 days; RB was defined as the recurrence of a positive blood culture ≥14 days following a negative culture. Isolates were typed using pulsed-field gel electrophoresis (PFGE). Vancomycin susceptibility was determined using Etest. RESULTS: A total of 183 patients with MRSA BSI were identified; 14 (7.7%) had PB and five (2.7%) had RB. Ten (5.5%) patients were known to have infective endocarditis, and five of these patients had PB or RB. Initial and subsequent MRSA isolates from patients with PB and RB had the same PFGE type. There were no significant differences in the distribution of PFGE types in patients with PB or RB (37% CMRSA-2/USA100; 37% CMRSA-10/USA300) compared with that in other patients (56% CMRSA-2/USA100; 32% CMRSA-10/USA300). All isolates were susceptible to vancomycin, but patients with PB or RB were more likely to have initial isolates with vancomycin minimum inhibitory concentration = 2.0 µg/mL (26% versus 10%; P=0.06). CONCLUSIONS: Persistent or recurrent MRSA bacteremia occurred in 10.4% of patients with MRSA BSIs. Initial isolates from patients with persistent or recurrent MRSA BSIs were more likely to exhibit reduced susceptibility to vancomcyin, but were not associated with any genotype.

HISTORIQUE: Les infections sanguines (IS) par le Staphylococcus aureus résistant à la méthicilline (SARM) s'associent à une morbidité et une mortalité considérables, particulièrement en présence d'une bactériémie persistante (BP) ou récurrente (BR). OBJECTIF: Déterminer la fréquence de BP et de BR chez les patients atteints d'une IS par le SARM et en caractériser les isolats. MÉTHODOLOGIE: Les chercheurs ont surveillé les IS par le SARM dans 13 hôpitaux canadiens pendant un an. La BP se définissait par une hémoculture positive qui persistait au moins sept jours, tandis que la BR désignait la récurrence d'une hémoculture positive au moins 14 jours après une hémoculture négative. Les chercheurs ont typé les isolats au moyen de l'électrophorèse sur gel en champ pulsé (ECP). Ils ont déterminé la susceptibilité à la vancomycine par Etest. RÉSULTATS: Les chercheurs ont retracé un total de 183 patients ayant une IS par le SARM. De ce nombre, 14 (7,7 %) avaient une BP et cinq (2,7 %), une BR. Dix patients (5,5 %) étaient atteints d'une endocardite infectieuse diagnostiquée, dont cinq avaient une BP ou une BR. Les isolats initiaux et subséquents de SARM chez les patients ayant une BP ou une BR présentaient le même type d'ECP. Il n'y avait pas de différence significative dans la distribution des types d'ECP chez les patients ayant une BP ou une BR (37 % de souche CSARM-2/USA100; 37% de souche CSARM-10/USA300) par rapport à celle des autres patients (56 % de souche CSARM-2/USA100; 32 % de souche CSARM-10/USA300). Tous les isolats étaient susceptibles à la vancomycine, mais les patients atteints d'une BP ou d'une BR étaient plus susceptibles de présenter des isolats initiaux de vancomycine dont la CMI = 2,0 µg/mL (26 % par rapport à 10 %; P=0,06). CONCLUSIONS: Les chercheurs ont observé une BP ou une BR par le SARM chez 10,4 % des patients atteints d'une IS par le SARM. Les isolats initiaux des patients atteints d'une IS persistante ou récurrente par le SARM risquaient davantage d'être moins susceptibles à la vancomycine, mais ne s'associaient à aucun génotype.

Antibiotic prescribing practices for catheter urine culture results.

BACKGROUND: The literature suggests that positive results of catheter urine cultures frequently lead to unnecessary antimicrobial prescribing, which therefore represents an important target for stewardship. OBJECTIVE: To assess the appropriateness of antibiotic prescribing in response to the results of urine cultures from patients with indwelling urinary catheters. METHODS: This retrospective study was conducted at a tertiary care centre and involved adults with indwelling urinary catheters from whom urine specimens were obtained for culture. Patients with positive or negative culture results were identified from microbiology laboratory reports. The medical records of consecutive patients were screened to select a sample of 80 inpatients (40 per group). Abstracted patient histories were independently evaluated by an expert panel of 3 infectious diseases consultants blinded to the decisions of prescribers and of fellow panelists. The primary end point was concordance of each patient's treatment decision (with respect to the indication) between the expert panel (based on majority agreement, i.e., at least 2 of the 3 expert panelists) and the prescriber. The secondary end points were unnecessary days of therapy and selected outcomes over a predefined period after urine was obtained for culture. RESULTS: A total of 591 charts were screened to generate the targeted number of patients. Baseline demographic characteristics were comparable for the 2 groups, except antibiotic exposure before urine collection was significantly more frequent for the group with negative culture results. The treatment decision was concordant in 40% (16/40) of the patients with a positive culture result and 85% (34/40) of those with a negative culture result (p < 0.001). The most common reason for discordance was administration of antibiotics when not indicated (23 of 24 patients with a positive result and 5 of 6 patients with a negative result), which accounted for 165 and 32 unnecessary days of therapy per 1000 inpatient-days, respectively (p < 0.001). Adverse effects occurred in 2 of the 23 patients with a positive result who received antibiotics that were not indicated. CONCLUSIONS: Appropriateness of antibiotic prescribing, as measured by concordance of decisions between the expert panel and prescribers, was more common among patients with negative urine culture results than among those with positive results. However, there is an opportunity to improve prescribing for both groups through antimicrobial stewardship initiatives. Unnecessary days of therapy and adverse effects were more common in patients with a positive culture result.

CONTEXTE: Selon la littérature, des résultats positifs à des cultures d'échantillons d'urine prélevés à partir d'une sonde vésicale entraînent souvent la prescription inutile d'antibiotiques; par conséquent, cette situation représente un objet important de gestion responsable des antimicrobiens. OBJECTIF: Évaluer la pertinence de la prescription d'antibiotiques sur la base de résultats des cultures d'échantillons d'urine prélevés chez les patients porteurs d'une sonde vésicale à demeure. MÉTHODES: La présente étude rétrospective a été menée dans un établissement de soins tertiaires auprès de patients adultes porteurs d'une sonde vésicale à demeure chez qui on a prélevé des échantillons d'urine à des fins de culture. Les patients avec des résultats de culture positifs ou négatifs ont été repérés à partir des rapports de microbiologie. Les dossiers médicaux d'une série consécutive de patients ont été examinés afin de choisir un échantillon de 80 patients hospitalisés (40 par groupe). Les historiques abrégés des patients ont été évalués indépendamment par un panel d'experts composé de trois consultants en maladies infectieuses qui ignoraient la décision des prescripteurs et les résultats des évaluations de leurs collègues panélistes. Le paramètre d'évaluation principal était la concordance de la décision thérapeutique (quant à l'indication) pour chaque patient entre le panel d'experts (selon un accord majoritaire, c.-à-d. au moins deux des trois panélistes experts) et le prescripteur. Les paramètres d'évaluation secondaires étaient le nombre de jours de traitement inutiles et certains résultats cliniques sur une période prédéterminée après l'obtention d'un échantillon d'urine à des fins de culture. RÉSULTATS: Un total de 591 dossiers de patients ont été analysés afin d'obtenir le nombre cible de patients pour l'étude. Les caractéristiques démographiques initiales étaient comparables dans les deux groupes, sauf l'exposition aux antibiotiques avant le prélèvement d'urine qui était significativement plus fréquente dans le groupe de patients ayant obtenu des résultats de culture négatifs. La décision thérapeutique concordait pour 40 % (16/40) des patients ayant obtenu des résultats positifs à la culture d'urine et pour 85 % (34/40) de ceux qui avaient obtenu des résultats négatifs (p < 0,001). La raison la plus fréquente expliquant la discordance entre les décisions thérapeutiques était l'administration non indiquée d'antibiotiques, une circonstance observée chez 23 patients sur 24 ayant obtenu des résultats positifs et 5 patients sur 6 ayant obtenu des résultats négatifs. Ces cas ont contribué respectivement à un total de 165 et de 32 jours de traitement inutiles par 1000 journées-patients hospitalisés (p < 0,001). Des effets indésirables sont survenus chez deux des 23 patients ayant obtenu un résultat positif et reçu des antibiotiques non indiqués. CONCLUSIONS: La pertinence de la prescription d'antibiotiques, telle qu'elle a été mesurée en fonction de la concordance des décisions entre le panel d'experts et les prescripteurs, était plus fréquente dans le cas des patients ayant obtenu des résultats négatifs à la culture d'urine que chez ceux dont ces résultats étaient positifs. Cependant, des mesures pour la gestion responsable des antimicrobiens pourraient améliorer la prescription dans les deux groupes. Le nombre de jours de traitement inutiles et les effets indésirables étaient plus fréquents chez les patients ayant obtenu des résultats positifs à la culture. [Traduction par l'éditeur].

Assessment of virulence diversity of methicillin-resistant Staphylococcus aureus strains with a Drosophila melanogaster infection model.

BACKGROUND: Staphylococcus aureus strains with distinct genetic backgrounds have shown different virulence in animal models as well as associations with different clinical outcomes, such as causing infection in the hospital or the community. With S. aureus strains carrying diverse genetic backgrounds that have been demonstrated by gene typing and genomic sequences, it is difficult to compare these strains using mammalian models. Invertebrate host models provide a useful alternative approach for studying bacterial pathogenesis in mammals since they have conserved innate immune systems of biological defense. Here, we employed Drosophila melanogaster as a host model for studying the virulence of S. aureus strains. RESULTS: Community-associated methicillin-resistant S. aureus (CA-MRSA) strains USA300, USA400 and CMRSA2 were more virulent than a hospital-associated (HA)-MRSA strain (CMRSA6) and a colonization strain (M92) in the D. melanogaster model. These results correlate with bacterial virulence in the Caenorhabditis elegans host model as well as human clinical data. Moreover, MRSA killing activities in the D. melanogaster model are associated with bacterial replication within the flies. Different MRSA strains induced similar host responses in D. melanogaster, but demonstrated differential expression of common bacterial virulence factors, which may account for the different killing activities in the model. In addition, hemolysin α, an important virulence factor produced by S. aureus in human infections is postulated to play a role in the fly killing. CONCLUSIONS: Our results demonstrate that the D. melanogaster model is potentially useful for studying S. aureus pathogenicity. Different MRSA strains demonstrated diverse virulence in the D. melanogaster model, which may be the result of differing expression of bacterial virulence factors in vivo.