Arcanobacterium haemolyticum Utilizes Both Phospholipase D and Arcanolysin To Mediate Its Uptake into Nonphagocytic Cells

The burden of Arcanobacterium haemolyticum pharyngitis: A systematic review and management algorithm

INTRODUCTION

Arcanobacterium haemolyticum causes pharyngotonsillitis in children and young adults. It is rarely isolated in pharyngeal swabs as testing for it is not routine. Data on complications, management, and antibiotic susceptibility testing is limited. We sought to review the available literature on the presentation and management of A. haemolyticum pharyngotonsillitis in this age group.

METHODS

A systematic review of eligible studies reporting pharyngotonsillitis and related complications in children and young adults caused by A. haemolyticum was conducted. Literature from case reports, case series, and available cohorts was compiled. Data were analyzed using descriptive statistics.

RESULTS

The initial database search yielded 63 articles, after applying exclusion criteria 17 studies were included. 191 patients were identified with a median age of 16.5 years. The most common presentation was throat pain reported in 93.7% of patients. Tonsillar exudates, fever at presentation and rash were present in more than half of the reviewed cases. The diagnosis was established by a positive culture on a pharyngeal swab in 98.8% of swabs collected. Complications described included peritonsillar abscesses, Lemierre's syndrome, pneumonia, and sepsis. Penicillin was the first line antibiotic in 81% of patients followed by macrolides in 19 patients (18%).

CONCLUSIONS

A. haemolyticum occurs in children and young adults and may result in complications. Our review supports its susceptibility to penicillin. We suggest a diagnostic and management algorithm to guide clinicians in targeted testing and aid with decision making regarding timely and appropriate antibiotic therapy, in an effort to reduce the burden of its complications.

Outbreak of Arcanobacterium haemolyticum in chronic wounds in The Netherlands

INTRODUCTION

Aging and comorbidities such as diabetes and vascular problems contribute to the increasing occurrence of chronic wounds. From the beginning of 2016, a marked increase in Arcanobacterium haemolyticum (ARH) in chronic wound cultures was noted among patients visiting a wound expertise centre in The Netherlands.

AIM

To report the outbreak investigation of ARH cultured from chronic wounds and describe the implemented infection prevention measures.

METHODS

In total, 50 ARH isolates were sent to a reference laboratory for molecular typing. Samples for bacterial culture and ARH polymerase chain reaction were taken from care workers, the environment and items used for wound care. Infection prevention measures were implemented in a bundled approach, involving education, better aseptic wound care conditions and hygienic precautions. Before and after the implementation of infection prevention measures, two screening rounds of ARH testing were performed among all patients receiving home care.

RESULTS

ARH isolates from wound care patients were found to be identical by core genome multi-locus sequence typing. No definite outbreak source could be determined by culture. However, three pairs of forceps, used by two nurses on multiple patients, were found to be ARH positive by polymerase chain reaction. In the two screening rounds before and after the implementation of infection prevention measures, the proportion of ARH-positive patients decreased significantly from 20% (20/99) to 3% (3/104). Subsequently, no new cases occurred.

CONCLUSION

This first ARH outbreak was likely caused by re-using contaminated instruments. Through the implementation of improved infection prevention measures and re-education of all employees involved, the outbreak was controlled. With the current trend of care transition, infection control must be a major concern.

Phobalysin: Fisheye View of Membrane Perforation, Repair, Chemotaxis and Adhesion

Phobalysin P (PhlyP, for photobacterial lysin encoded on a plasmid) is a recently described small β-pore forming toxin of Photobacterium damselae subsp. damselae (Pdd). This organism, belonging to the family of Vibrionaceae, is an emerging pathogen of fish and various marine animals, which occasionally causes life-threatening soft tissue infections and septicemia in humans. By using genetically modified Pdd strains, PhlyP was found to be an important virulence factor. More recently, in vitro studies with purified PhlyP elucidated some basic consequences of pore formation. Being the first bacterial small β-pore forming toxin shown to trigger calcium-influx dependent membrane repair, PhlyP has advanced to a revealing model toxin to study this important cellular function. Further, results from co-culture experiments employing various Pdd strains and epithelial cells together with data on other bacterial toxins indicate that limited membrane damage may generally enhance the association of bacteria with target cells. Thereby, remodeling of plasma membrane and cytoskeleton during membrane repair could be involved. In addition, a chemotaxis-dependent attack-and track mechanism influenced by environmental factors like salinity may contribute to PhlyP-dependent association of Pdd with cells. Obviously, a synoptic approach is required to capture the regulatory links governing the interaction of Pdd with target cells. The characterization of Pdd’s secretome may hold additional clues because it may lead to the identification of proteases activating PhlyP’s pro-form. Current findings on PhlyP support the notion that pore forming toxins are not just killer proteins but serve bacteria to fulfill more subtle functions, like accessing their host.