Fusariumref
is a filamentous fungus widely distributed on plants and in the soil. It
is found in normal mycoflora of commodities such as rice, bean, soybean,
and other crops. While most species are more common at tropical and subtropical
areas, some inhabit in soil in cold climates. The genus Fusarium
currently contains > 20 species. The most common of these are F. solani,
F. oxysporum, and
F. chlamydosporum. As well as being common
contaminants and well-known plant pathogens, Fusarium spp are causative
agents of superficial and systemic infections in humans. Infections due
to Fusarium spp are collectively referred to as fusariosis.
The most virulent species in man is Fusarium
solani.
Transmission :
-
trauma is the major predisposing factor for development of cutaneous or
corneal infections due to Fusarium strains
-
disseminated opportunistic infections, on the other hand, develop in immunosuppressed
hosts, particularly in neutropenic and transplant patients
-
Fusarium infections following
solid
organ transplantation
tend to remain local and have a better outcome than those that develop
in patients with hematological malignancies and HSCT
patients
-
outbreaks of nosocomial fusariosis have also been reported. Existence of
Fusarium
in hospital water distribution systems may result in disseminated fusariosis
in immunosuppressed patients. Fusarium may also exist in soil of
potted plants in hospitals. These plants constitute a hazardous mycotic
reservoir for nosocomial fusariosis.
Fusarium
spp can produce mycotoxins.
=> ophthalmologic infections related to fusariosis include
keratomycosis
(involvement of the cornea) and, less commonly, endophthalmitis (involvement
of the inner part of the eye). Other infections associated with this mold
include those of nail, skin, lung, heart valve, peritoneum, joint, and
central venous catheter. Disseminated infections with or without fungemia
due to
Fusarium spp. have been reported in immunoincompetent hosts
primarily. 39 cases of
Fusarium keratitis occurred in Singapore
from May 2005 to January 2006 because of contamination of disposable Bausch
and Lomb's ReNu soft contact lenses, which were cleaned and stored with
multi-purpose contact lens solution : 3 patients had to undergo urgent
corneal transplantation
ref1,
ref2.
130 confirmed cases in USA since 1 Jun 2005 to 18 May 2006 : cases have
been reported from 26 states and one territory.* Patients had a median
age of 41 years (range: 12-83 years), and 85 of 127 (67%) were female.
As a result of this infection, corneal transplantation was required in
37 of 120 (31%) cases. Among the 130 patients with confirmed cases, 125
reported wearing contact lenses, and 118 were able to identify which contact
lens solution(s) they had used during the month before onset of infection.
75 (64% reported using Bausch & Lomb's ReNu with MoistureLoc alone,
14 (12%) reported using MoistureLoc in combination with another product,
8 (7%) reported using an unspecified Bausch & Lomb solution, and 21
(18%) reported using only products other than MoistureLoc, from various
manufacturers
ref1,
ref2.
21 patients, including 12 soft-lens wearers (29 millions in USA) have been
infected in South Florida since January to March 2006 (typically 21 per
year, virtually all among patients with eye trauma that lets the fungus
penetrate the cornea. The fungus is common in soil and plants in tropical
regions like South Florida : wearers should clean their lenses well and
not wear them while sleeping, even those models approved for overnight
use. 3 cases were reported in the New York metropolitan area and eye specialists
in Tampa, Atlanta, Texas and California also had cases
ref1,
ref2,
ref3.
In USA the annual incidence of microbial keratitis is estimated to be 4-21
per 10 000 soft contact lens users, depending on whether users wear lenses
overnight
ref.
Fungal keratitis is a condition more prevalent in warm climates; in the
southernmost USA, up to 35% of microbial keratitis cases are fungal keratitis,
compared with one percent in New York
ref1,
ref2.
The proportion of fungal keratitis attributable to
Fusarium spp.
also varies by region, from 25% to 62%
ref1,
ref2,
ref3.
Alexidine is an antiseptic in the biguanide family that has bactericidal
properties
ref.
Fusarium
keratitis is not transmitted from person to person. It is safe and effective,
but under certain extreme conditions -- such as when the solution is allowed
to evaporate, the solution is not regularly replaced in the lens case,
when the bottle is kept open in between uses or when the case is not cleaned
properly or changed regularly -- the concentration of polymers included
in the formula to enhance comfort may make the solution more likely to
be contaminated with Fusarium in the environment
=> ingestion of grains contaminated with these toxins may give rise
to allergic symptoms or be carcinogenic in long-term consumption.
Fumonisins
are the mycotoxins produced by
F. moniliforme and
F. proliferatum
in maize. These toxins may be associated with a risk of
esophageal
cancer
ref
Therapyref
: first line treatment includes topical and oral antifungal medications;
patients who do not respond to medical treatment usually require surgical
intervention, including corneal transplantation
ref