Infective Endocarditis Related to Unusual Microorganisms: A Prospective Population-Based Study

[Not Available]

INTRODUCTION

Prevotella species (i. e. P. intermedia, P. nigrescens, P. pallens, P. oris) are usually responsible for abscesses of head and neck spaces after dental procedures. P. intermedia - related infective endocarditis has never been reported.

CASE REPORT

A 22-year-old man, with a history of aortic valve replacement 6 years ago, presented with fever and persistent retrosternal chest pain. An empirical antibiotic therapy was started on (cefotaxime, 2gx3 - gentamicin, 5mg/kilo). Five blood cultures were positive at Prevotella Intermedia. Metronidazole was introduced (500mg X 3 by day).The oro-pharyngeal spaces were normal. The evolution was marked by a hypotension, a third degree atrio-ventricular block, and a rapidly growing aortic root abscess complicated this case of Prevotella Intermedia infective endocarditis (IE). Aortic valve redux surgery was performed at day 5 of admission. Post-operative course was unremarkable.

CONCLUSION

This first reported case of Prevotella Intermedia IE presented suggestive features of anaerobic IE as the patient developed both aortic-ring abscess, third degree atrio-ventricular block and hypotension.

A Rare Case of Successfully Treated Double Valve Infective Endocarditis Caused by Pseudomonas aeruginosa

Pseudomonas aeruginosa is a rare yet particularly aggressive infective endocarditis pathogen. We describe a case of successfully managed double-valve P. aeruginosa infective endocarditis, in which the presumed source of bacteremia was a long-term tunneled central venous catheter used for hemodialysis.

Haemophilus parainfluenzae endocarditis presenting with symptoms of COVID-19

A young man presented early in the UK's second COVID-19 pandemic surge with a twelve-day history of fever, dry cough, breathlessness, myalgia and loss of smell and taste. His chest X-ray showed bilateral ground-glass opacities. He was treated for COVID-19 pneumonitis but covered for bacterial infection with antibiotics. He developed shock and respiratory failure, requiring vasopressors and continuous positive airway pressure. He improved but experienced transient visual disturbances and headache. Nasopharyngeal swabs and antibody tests for COVID-19 were negative. Blood cultures grew Haemophilus parainfluenzae A new murmur prompted an echocardiogram. This confirmed a large, mobile mitral valve vegetation. An MRI of the brain showed bilateral embolic infarcts. He underwent urgent mitral valve repair and made an excellent recovery. Whether COVID-19 caused his presenting symptoms or facilitated the bacteraemia remains unclear. It seems more likely that infective endocarditis masqueraded as COVID-19. Clinicians should be aware of how context of the pandemic can bias diagnostic reasoning.

Antimicrobial susceptibility profiles of invasive isolates of anaerobic bacteria from a large Canadian reference laboratory: 2012-2019

Anaerobic bacteria can cause severe and life threatening infections. Susceptibility data are relatively limited on anaerobic organisms despite the clinical importance in guiding empiric treatment of infections. To determine antimicrobial susceptibility profiles of clinically significant anaerobic bacteria, isolates obtained from sterile sites submitted to Public Health Ontario Laboratory (2012-2019) were included in this study (N = 5712). Cefoxitin, clindamycin, metronidazole, meropenem, penicillin and piperacillin-tazobactam were tested using the gradient strip method with MICs interpreted based on Clinical and Laboratory Standards Institute guidelines. Bacteroides spp. (N = 958; 16.7%), Clostridium spp. (N = 798; 14.0%), Cutibacterium spp. (N =659; 11.5%) and Actinomyces spp. (N = 551; 7.0%) were the most commonly isolated genera. Bacteroides fragilis isolates were susceptible to cefoxitin (88.4%), clindamycin (68.4%), metronidazole (96.0%), meropenem (99.0%) and piperacillin-tazobactam (98.4%). Other Bacteroides spp. showed reduced susceptibility to several antimicrobials. Clostridium spp. isolates were susceptible to penicillin (69.7%), clindamycin (69.7%) and cefoxitin (76.3%); C. perfringens and C. ramosum showed distinct susceptibility profiles. Susceptibility rates among anaerobes remained relatively unchanged over 8 years with a few exceptions: C. perfringens susceptibility to clindamycin decreased from 91.3% to 60% (p = 0.03); Clostridium spp. susceptibility to penicillin similarly decreased from 82.1% to 65.9% (p = 0.03); Eggerthella spp. susceptibility to piperacillin-tazobactam decreased from 100% to 24.3% (p < 0.001); B. fragilis group susceptibility to cefoxitin decreased from 70.4% to 48.2% (p = 0.05); and Parabacteroides spp. susceptibility to piperacillin-tazobactam decreased from 100% to 25% (p = 0.01). Our findings underscore the need for ongoing surveillance and periodic monitoring of antimicrobial resistance in order to guide empiric therapy.

Mycobacterium chimaera Genomics With Regard to Epidemiological and Clinical Investigations Conducted for an Open Chest Postsurgical Mycobacterium chimaera Infection Outbreak

Background

Postsurgical infections due to Mycobacterium chimaera appeared as a novel nosocomial threat in 2015, with a worldwide outbreak due to contaminated heater-cooler units used in open chest surgery. We report the results of investigations conducted in France including whole-genome sequencing comparison of patient and heater-cooler unit isolates.

Methods

We sought M. chimaera infection cases from 2010 onwards through national epidemiological investigations in health care facilities performing cardiopulmonary bypass, together with a survey on good practices and systematic heater-cooler unit microbial analyses. Clinical and heater-cooler unit isolates were subjected to whole-genome sequencing analyzed with regard to the reference outbreak strain Zuerich-1.

Results

Only 2 clinical cases were shown to be related to the outbreak, although 23% (41/175) of heater-cooler units were declared positive for M. avium complex. Specific measures to prevent infection were applied in 89% (50/56) of health care facilities, although only 14% (8/56) of them followed the manufacturer maintenance recommendations. Whole-genome sequencing comparison showed that the clinical isolates and 72% (26/36) of heater-cooler unit isolates belonged to the epidemic cluster. Within clinical isolates, 5–9 nonsynonymous single nucleotide polymorphisms were observed, among which an in vivo mutation in a putative efflux pump gene was observed in a clinical isolate obtained for 1 patient on antimicrobial treatment.

Conclusions

Cases of postsurgical M. chimaera infections have been declared to be rare in France, although heater-cooler units were contaminated, as in other countries. Genomic analyses confirmed the connection to the outbreak and identified specific single nucleotide polymorphisms, including 1 suggesting fitness evolution in vivo.