Arcanobacterium hemolyticum infection: confused with scarlet fever and diphtheria

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.

Exudative pharyngitis possibly due to Corynebacterium pseudodiphtheriticum, a new challenge in the differential diagnosis of diphtheria

Corynebacterium pseudodiphtheriticum has rarely been reported to cause disease in humans, despite its common presence in the flora of the upper respiratory tract. We report here a case of exudative pharyngitis with pseudomembrane possibly caused by C. pseudodiphtheriticum in a 4-year-old girl. The case initially triggered clinical and laboratory suspicion of diphtheria. Because C. pseudodiphtheriticum can be easily confused with Corynebacterium diphtheriae in Gram stain, clarification of its role in the pathogenesis of exudative pharyngitis in otherwise healthy persons is of public health importance. Simple and rapid screening tests to differentiate C. pseudodiphtheriticum from C. diphtheriae should be performed to prevent unnecessary concern in the community and unnecessary outbreak control measures.

Are penicillin treatment failures in Arcanobacterium haemolyticum pharyngotonsillitis caused by intracellularly residing bacteria?

Arcanobacterium haemolyticum is an infrequent agent of pharyngotonsillitis in children and young adults. Despite the fact that A. haemolyticum is fully sensitive to penicillin in vitro, penicillin treatment failures are frequent. The ability of A. haemolyticum to invade HEp-2 cells and survive intracellulary was investigated. All 12 strains tested, of which 10 were isolated from patients with pharyngotonsillitis, and 2 were reference strains, were internalized by the HEp-2 cells. Four strains tested further, one of the reference strains and 3 of the clinical isolates, proved able to survive intracellularly for 4 days, thus creating intracellular reservoirs of bacteria. It was also shown that erythromycin, an antibiotic known to penetrate well intracellularly, efficiently killed these bacteria.

Effects of media, atmosphere, and incubation time on colonial morphology of Arcanobacterium haemolyticum

Arcanobacterium haemolyticum causes pharyngitis as well as skin and other wound infections. Although it is a beta-hemolytic organism, the hemolysis is less well defined than that of beta-hemolytic streptococci and may be overlooked in cultures with heavy growth of commensal throat flora. To determine whether routine throat culture conditions are sufficient to produce recognizable colonies of A. haemolyticum, the morphology of six distinct strains was studied after various combinations of incubation time, medium, and atmosphere. The agar media, containing 5% sheep blood, were Trypticase soy agar, Columbia agar, and heart infusion agar. Cultures were incubated in ambient air, 6 to 8% CO2, or an anaerobic atmosphere. Cultures were compared after 24, 48, and 72 h of incubation for colony size, clarity and size of hemolytic zone, and macroscopic evidence of agar pitting. A minimum of 48 h was needed for expression of beta-hemolysis and pitting. Trypticase soy agar was the superior medium and CO2 was the superior atmosphere for beta-hemolysis. Agar pitting was not significantly affected by variations in medium or atmosphere. Strains differed in their expression of hemolysis and production of pits at 48 h. After 72 h of incubation, beta-hemolysis and pitting were visible in over 96% of culture observations.

Adult and pediatric pharyngitis: a review

Acute pharyngitis is frequently encountered in the ambulatory care setting. Although usually of viral etiology, streptococcal disease is the focus of diagnostic efforts, in light of significant suppurative and nonsuppurative sequelae. The traditional symptoms of fever, adenopathy, and pharyngeal exudate are suggestive, but not diagnostic of streptococcal pharyngitis. Thus, the importance of diagnostic testing, including Group A beta hemolytic strep antigen screen and culture, is emphasized. Recent innovations in therapy include modification of antibiotic dosing regimens and use of cephalosporins to improve patient compliance.