A review of the virulence factors of pathogenic fungi

C. Iyalla

 

Abstract

Fungal infections are becoming more prevalent especially with increase in immunodeficiency disorders, immunosuppression following transplantation, cancers and cancer treatment. They are ubiquitous and cause infections which may be trivial or more deep seated and severe infections associated with mortality. The ability of some fungal species to cause disease is due to various virulence factors which help with fungal survival and persistence in the host resulting in tissue damage and disease. This review discusses these virulence factors. These factors include an ability to adhere to hosts’ tissues, production of enzymes that cause tissue damage and direct interference with host defences. Pathogenic fungi produce catalases and Mannitol which protect against reactive oxygen species (ROS). Some fungi notably, dimorphic fungi and C. albicans have the ability to switch from one form to another. Thermotolerance, at least to 370C, is critical for survival in mammalian host and contributes to dissemination. Melanin is produced by a number of pathogenic fungi, and protects against harsh conditions such as UV radiation, increased temperature and ROS. The ability to obtain Iron (Fe) from the storage or transport forms in the host is also a virulence factor and calcineurin acts as a sensor for pathogenic fungi.

Keywords: Fungi, virulence, pathogenic, infections, dimorphism, thermotolerance

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A review of the virulence factors of pathogenic fungi

Trends in profiles of bacteria causing neonatal sepsis in Central Nigeria Hospital

N. Medugu, K.C. Iregbu

 

Abstract

Developing countries suffer from a huge burden of neonatal sepsis. Neonatal  mortality and long term sequelae or morbidity portends huge costs for the poor Nigerian economy. We identified trends in bacterial agents implicated in neonatal sepsis and their antibiotic susceptibility profiles at the National Hospital Abuja over two periods of three years each a decade apart. A retrospective study of bacterial agents of sepsis from 2013-2015 was carried out and this was compared to an already published study from the same hospital ten years earlier(2002-2004) to determine changing trends using standard statistical methods. We identified a significant shift to predominance of gram positive organisms especially Staphylococcus aureus (59% vs 40%) as against the predominance of gram negative organisms especially Klebsiella pneumoniae (11% vs 44%) in the previous decade. Almost all antibiotics tested (92%) had reduced susceptibility in the later review compared to the former. Surveillance of bacterial agents of neonatal sepsis is vital for the detection of trends in causative organisms and their susceptibilities. This is important to direct empiric therapy and also to encourage implementation and monitoring of antibiotic stewardship programs.

Comparing antibody responses to Onchocerca volvulus and non-parasite antigens in placebo-controlled and ivermectin-treated onchocerciasis patients

H.O Osue, F.N.C Enwezor, B.T. Idowu, A. Cassel-Brown, B. Jones, A. Abiose, F Engelbrecht, H. Edeghere

 

Abstract

Serum antibodies to parasite-specific and non-parasite antigens were evaluated  using enzyme-linked immunosorbent assay (ELISA). Out of the 470 sera collected, 409 were from residents of an onchocerciasis hyper-endemic area, 55 non-endemic and 6 European normal sera served as control. The patients’ age, sex, skin  microfilaria densities, dermal and ocular clinical manifestations (colour of optic disc) have been well characterised. The study population had participated in a  placebocontrolled (n=191) trial of ivermectin (Mectizan®) treatment (n=218). The parasite antigens are phosphate buffered saline crude extract of adult worms of Onchocerca volvulus, a recombinant antigen (Ov1.9) and a monoclonal antibody purified antigen (Cam 1). The non-parasite antigens are deoxycholate citrate extract of optic nerve (nerve-DOC) and commercially available IgA, IgM and IgG were used to assay for rheumatoid factor (Rh-F) auto-antibodies. Generally, antibodies to parasite antigens in onchocerciasis patients were remarkably higher than control group (p<0.05) using exact F-test. There was no significant difference (p>0.05) in antibodies to nerve-DOC and Rh-F in patients compared to control. Antibodies increased with increasing skin snip microfilaria load from 0.69±0.28 with 0mf/mg (n=54) as against 0.80±0.26 for those with 4-20mf/mg. Observed slight negative correlation in IgG antibody levels and severity of disc colour with mean OD values of 0.26±0.22 in those graded as having no optic nerve disease (OND) (disc 1, n=86) and 0.17±0.19 for those with severe changes (disc 3, n=49) was not statistically significant (P>0.05). An age dependent significant decrease (P<0.05) in antibodies were observed with 0.64±0.34 for 15-30yr old (n=48) compared to 0.48±0.35 for those 50yr (n=50) for PBS with a similar trend for IgG to Ov1.9 and Cam1. In conclusion, serum parasite-specific and non-parasite antibodies may not be responsible for the pathology of optic nerve disease. Onchocerciasis patients were apparently not at higher risk of developing rheumatoid arthritis than the control.

Keywords: Onchocerciasis; Antibodies; Antigens; Immune responses; Ivermectin.

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Comparing antibody responses to Onchocerca volvulus and non-parasite antigens in placebo-controlled and ivermectin-treated onchocerciasis patients