Haemolytic and co‐haemolytic (CAMP‐like) activity in dermatophytes

Abstract

Dermatophytes are some of the most common fungal pathogens in both humans and animals. These fungi release enzymes (e.g., keratinases) that play roles in their pathogenesis. Little is known about their haemolytic and co-haemolytic (CAMP-like) activities; however, in bacteria, these components play significant roles in pathogenesis. This study characterised these two factors in 45 dermatophyte strains (representing the genera Arthroderma, Epidermophyton, Microsporum and Trichophyton) using Columbia agar (CA) supplemented with 5% bovine, ovine and equine erythrocytes. Haemolysis was best observed on CA supplemented with ovine erythrocytes followed by equine and bovine erythrocytes, while CAMP-like reactions occurred using bovine and ovine but not equine erythrocytes. Haemolytic and CAMP-like activities were best observed using ovine and bovine erythrocytes in CA in 44 and 38 strains at 7 and 3 days respectively. Most dermatophytes recovered from both symptomatic and asymptomatic lesions had haemolytic and CAMP-like activities. We suggest that the haemolytic and CAMP-like activities are not correlated with ecological characteristics, isolation sites or clinical manifestations of dermatophytic fungi. We also believe that this study has the potential to contribute to the existing literature on dermatophytes and dermatophyte pathogenesis.

Virulence markers of opportunistic black yeast in Exophiala

“…Fungi that are adapted to reside in mammalian tissues are hypothesised to possess the ability to secrete the appropriate hydrolytic enzymes needed to feed on host cell compounds. The main categories of such compounds are proteinases that hydrolyse peptide bonds, phospholipases to digest phospholipids and haemolysins . Exophiala black yeast enter the human host from the environment and the infected hosts are not contagious, suggesting that environmental strains should have a set of virulence factors similar to that of clinical strains.…”

“…Haemolysin mediates the severity of infectious diseases, and loss of this activity often results in avirulence, particularly in bacteria . Haemolytic activity has been described in Aspergillus , Candida and dermatophytes . Dermatophyte strains recovered from both symptomatic and asymptomatic lesions have been shown to have haemolytic and co‐haemolytic activities using COA and CBA .…”

“…Haemolytic activity has been described in Aspergillus , Candida and dermatophytes . Dermatophyte strains recovered from both symptomatic and asymptomatic lesions have been shown to have haemolytic and co‐haemolytic activities using COA and CBA . However, these activities were absent from the black yeast evaluated.…”

“…To increase haemolytic activity, strains were additionally incubated at 36 °C for 1–5 days. Haemolytic activity was measured macroscopically, and test results were recorded each day …”

“…CAMP‐like reactions were examined daily for 7 days. The presence of a distinct arrowhead of haemolysis at the intersection between the tester strain and the test Exophiala streaks was considered as positivity …”