Inactivation of the dnaK gene in Clostridium difficile 630 Δerm yields a temperature-sensitive phenotype and increases biofilm-forming ability

Abstract Clostridium difficile infection is a growing problem in healthcare settings worldwide and results in a considerable socioeconomic impact. New hypervirulent strains and acquisition of antibiotic resistance exacerbates pathogenesis; however, the survival strategy of C. difficile in the challenging gut environment still remains incompletely understood. We previously reported that clinically relevant heat-stress (37–41 °C) resulted in a classical heat-stress response with up-regulation of cellular chaperones. We used ClosTron to construct an insertional mutation in the dnaK gene of C. difficile 630 Δerm. The dnaK mutant exhibited temperature sensitivity, grew more slowly than C. difficile 630 Δerm and was less thermotolerant. Furthermore, the mutant was non-motile, had 4-fold lower expression of the fliC gene and lacked flagella on the cell surface. Mutant cells were some 50% longer than parental strain cells, and at optimal growth temperatures, they exhibited a 4-fold increase in the expression of class I chaperone genes including GroEL and GroES. Increased chaperone expression, in addition to the non-flagellated phenotype of the mutant, may account for the increased biofilm formation observed. Overall, the phenotype resulting from dnaK disruption is more akin to that observed in Escherichia coli dnaK mutants, rather than those in the Gram-positive model organism Bacillus subtilis

Usefulness and limitations of transthoracic echocardiography in heart transplantation recipients

Transthoracic echocardiography is a primary non-invasive modality for investigation of heart transplant recipients. It is a versatile tool which provides comprehensive information about cardiac structure and function. Echocardiographic examinations can be easily performed at the bedside and serially repeated without any patient's discomfort. This review highlights the usefulness of Doppler echocardiography in the assessment of left ventricular and right ventricular systolic and diastolic function, of left ventricular mass, valvular heart disease, pulmonary arterial hypertension and pericardial effusion in heart transplant recipients. The main experiences performed by either standard Doppler echocardiography and new high-tech ultrasound technologies are summarised, pointing out advantages and limitations of the described techniques in diagnosing acute allograft rejection and cardiac graft vasculopathy. Despite the sustained efforts of echocardiographic technique in predicting the biopsy state, endocardial myocardial biopsies are still regarded as the gold standard for detection of acute allograft rejection. Conversely, stress echocardiography is able to identify accurately cardiac graft vasculopathy and has a recognised prognostic in this clinical setting. A normal stress-echo justifies postponement of invasive studies. Another use of transthoracic echocardiography is the monitorisation and the visualisation of the catheter during the performance of endomyocardial biopsy. Bedside stress echocardiography is even useful to select appropriately heart donors with brain death. The ultrasound monitoring is simple and effective for monitoring a safe performance of biopsy procedures

El desafío de la administración adecuada de antimicrobianos en pediatría.

Background: Antibiotics are among the drugs most commonly prescribed to children in hospitals and communities. Unfortunately, a great number of these prescriptions are unnecessary or inappropriate. Antibiotic abuse and misuse have several negative consequences, including drug-related adverse events, the emergence of multidrug resistant bacterial pathogens, the development of Clostridium difficile infection, the negative impact on microbiota, and undertreatment risks. In this paper, the principle of and strategies for paediatric antimicrobial stewardship (AS) programs, the effects of AS interventions and the common barriers to development and implementation of AS programs are discussed. Discussion: Over the last few years, there have been significant shortages in the development and availability of new antibiotics; therefore, the implementation of strategies to preserve the activity of existing antimicrobial agents has become an urgent public health priority. AS is one such approach. The need for formal AS programs in paediatrics was officially recognized only recently, considering the widespread use of antibiotics in children and the different antimicrobial resistance patterns that these subjects exhibit in comparison to adult and elderly patients. However, not all problems related to the implementation of AS programs among paediatric patients are solved. The most important remaining problems involve educating paediatricians, creating a multidisciplinary interprofessional AS team able to prepare guidelines, monitoring antibiotic prescriptions and defining corrective measures, and the availability of administrative consensuses with adequate financial support. Additionally, the problem of optimizing the duration of AS programs remains unsolved. Further studies are needed to solve the above mentioned problems. Conclusions: In paediatric patients, as in adults, the successful implementation of AS strategies has had a significant impact on reducing targeted- and nontargeted-antimicrobial use by improving the quality of care for hospitalized patients and preventing the emergence of resistance. Considering that rationalization of antibiotic misuse and abuse is the basis for reducing emergence of bacterial resistance and several clinical problems, all efforts must be made to develop multidisciplinary paediatric AS programs in hospital and community settings

Availability, perceptions, and characteristics of antibiograms among Illinois pediatricians

Kathryn M Spiekerman,1 Sameer J Patel,2,3 Rupal Patel,4 Larry K Kociolek,2,3 1School of Public Health, University of Illinois at Chicago, 2Division of Pediatric Infectious Diseases, Ann & Robert H. Lurie Children’s Hospital of Chicago, 3Department of Pediatrics, Northwestern University Feinberg School of Medicine, 4Department of Pharmacy, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, USA Abstract: Despite the enormous volume of antibiotics prescribed by pediatricians, resources to promote judicious antibiotic use are primarily limited to hospitals. The primary objective of this survey was to delineate the availability, characteristics, and perceptions of antibiograms among pediatricians. As a secondary objective, we sought to delineate the availability of other infectious diseases (ID)-related educational resources among pediatricians, the perceived need for additional resources, and their general educational preferences. We developed an anonymous electronic survey using the Research Electronic Data Capture tool, and it was sent via email to all members of the Illinois Chapter of the American Academy of Pediatrics (ICAAP). Participants were excluded if they had not completed pediatrics residency or if they had not prescribed antibiotics in the past month. Of the 1,825 ICAAP members, 294 (16%) responded; of these, 239 (81%) were eligible and completed the survey. Of the 239 respondents, 139 (58%) had access to an antibiogram and 60 (25%) had access to a pediatric-specific antibiogram. Access to a pediatric-specific antibiogram was associated with subspecialty training (P=0.007) and practice location in Chicago (P<0.0001). Antibiogram access was associated with perceiving being informed about resistance patterns at the national (67% vs 54%, P=0.043) and local (76% vs 45%, P<0.0001) levels. Nearly all (95%) respondents would probably or definitely use a single antibiogram that compiled antibiotic resistance data from children with common infections throughout the region. More than 75% of respondents identified both the American Academy of Pediatrics Red Book and online medical resources among the top three most useful and most frequently accessed educational resources. In addition, 91% of respondents utilized smartphones/tablets. These data suggest that there is an unmet need for additional educational resources to guide antibiotic prescribing among Illinois pediatricians. In addition, an electronic regional antibiogram would be well received and could potentially improve knowledge of antibiotic resistance and empiric antibiotic use. Keywords: antibiotic stewardship, antibiogram, survey, pediatric

Correlation between restriction endonuclease analysis and PCR ribotyping for the identification of Clostridioides (Clostridium) difficile clinical strains

Restriction endonuclease analysis (REA) and PCR ribotyping are two typing systems that have been frequently utilized for molecular epidemiologic characterization of Clostridioides (Clostridium) difficile. To correlate typing data obtained from each method, we performed both REA and PCR ribotyping on a large and diverse set of historical and contemporary C. difficile infection clinical isolates. Eighty isolates were selected from each reference laboratory in the United States (Microbiology Reference Laboratory, Hines VA Medical Center) and United Kingdom (Clostridium difficile Network for England and Northern Ireland laboratory, University of Leeds). The 160 isolates were assigned to 82 unique ribotypes and 51 unique REA groups (116 unique REA types). In general, concordance between typing methods was good. Dendrogram analysis of PCR ribotype band patterns demonstrated close genetic relationships among strain types with discordant REA and ribotype assignments. While REA typing was more discriminatory, several REA types in this study were further discriminated by PCR ribotyping, indicating that discriminatory value of these typing methods may be strain dependent. These data will assist with molecular epidemiologic surveillance of strains identified by these two commonly used C. difficile typing systems