Rhizopus spp.

The zygomycete organism, Rhizopus spp. is commonly found in dusty environments inside buildings.  It is capable of rapidly overgrowing a culture plate in 2 to three days at both 25 and 37 degrees Celsius. 

The organism has been found to be the cause of opportunistic infections in immune compromised individuals.

Growth is rapid on PDA and MEA.  Growth is restricted on DG-18 agar due to the inhibiting effects of the dichloran.  The organism can be identified on an Air-O-Cell cassette sample if several are present in the sample.  The spore looks a bit like a very tiny walnut shell with ridges and an irregular assymetric shape.

Rhizopus spp. line drawing - N.Carlson

Rhizopus spp. spores at 400x - N. Carlson

Rhizopus spp. growth in culture- Dark heads on the periphery - N. Carlson

Rhizopus spp. in culture 100x - Note distintictive root like structure at the base - N. Carlson

Tritirachium spp.

Some species of Tritirachium spp. can produce a beautiful lavender color if grown under the right conditions on a culture plate.  The growth is restricted.  It could be used creatively to produce fungal artwork. 

The structure is very delicate.  Spores of less than 3 microns are produces on alternating ratchet like structures at the ends of fairly large conidiophores.  These structures are close to one micron in size and are difficult to view with an optical microscope.

The spores are unremarkable in size and shape and are very difficult to identify on an Air-O-Cell cassette air sample. 



Tritirachium spp.- Line Drawing - N. Carlson
 

Tritirachium spp. growth on culture - N. Carlson
 

Tritirachium spp. growing in culture at 400x - N. Carlson

Acremonium spp.

The fungus Acremonium spp. covers a group of fungi characterized by spores in chains or in clumps at the end of a pointed conidiophore.  The organism is often found in damp insulation.  Colonies are usually white in culture.  It grows best on PDA and MEA and less well on DG-18. The growth on the culture plate somewhat restricted.  The organism is difficult to identify on an Air-O-Cell cassette sample as the spore is unremarkable in size and shape.  It may be able to be identified presumptively if it is in chains or in a cluster.

Acremonium spp. line drawing - N. Carlson

Acremonium spp.  spores in clusters in culture - N. Carlson

Acremonium spp. in culture spores in chains - N. Carlson

Acremonium spp. growth in culture. - N. Carlson

Memnoniella spp

The fungus, Memnoniella spp.  is closely related to Stachybotrys spp.  It has a similar conidiophore.  Unlike Stachybotrys spp. the dark spores are round and in chains.  Like Stachybotrys spp. the organism has a preference for materials with cellulose.  Wet untreated sheetrock is often a source.

Growth on MEA and PDA is better than DG-18.  It can be found on Air-o-cell cassette air samples but it can be difficult to distinguish between Memnoniella spp. and Aspergillus niger.   The Memnoniella spp. spores are often darker. 

Memnoniella spp. - Line Drawing N. Carlson

Memnoniella spp. in culture N. Carlson

Memnoniella spp. from a tease tape. 400x each small tick mark is 2.5 microns -  N. Carlson

Memnoniella spp. growing on sheetrock - N. Carlson

Aspergillus niger

The fungi, Aspergillus niger can be used to describe the species or a group of Aspergillus spp. with dark spores  and large radiate heads.   It is commonly found in dusty areas of buildings on carpet and elevated surface samples.   It is an infrequent cause of aspergillosis in immune compromised individuals.  In can grow well at 25 to 37 degrees Celsius.

Growth in culture is often rapid depending on the media.  The organism grows well on PDA, MEA and DG-18.  It can be difficult to distinguish between Aspergillus niger spores and Memnoniella spp. spores on an Air-o-cell cassette sample. 



Aspergillus niger - Line Drawing - N. Carslon
 

Lower power 100x Aspergillus niger in culture - N. Carlson

 

Aspergillus niger on media - N. Carlson

 

Aspergillus niger - 100x N. Carlson

Aspergillus niger 100x - Note air bubbles present near vesicles - N. Carlson

 

 

Aspergillus niger spores 4-5 microns rough 400x

 

Cladosporium spp.

The fungus, Cladosporium spp. is one of the most commonly identified outdoor fungi from spring to late fall. Outdoor species can often differ from those found inside.  Cladosporium herbarium is more commonly found outside.  Cladosporium sphaerospermum is commonly found indoors growing on dusty cold surfaces.  These surfaces include window sills, concrete walls, supply diffusers, shower walls and labels on bottles stored in walk in coolers. 

The organisms is usually the most commonly identified organism in normal carpet dust and is often found on dusty horizontal surfaces in homes and offices.  For some individuals this organism can be the cause of seasonal allergies.

Cladosporium spp. line drawing - N. Carlson
 

Cladosporium Sphaerospermum - N. Carlson

 

Cladosporium spp. growing in culture. N. Carlson

 

Cladosporium spp. spores in an Air-o-cell cassette outdoor air sample. N. Carlson

 

Mold Remediation Course April 2013

Update.  The course was successful with students from around the state.  There may be another offering in 2013.  There was also some interest in a two day fungal identification course.  Please register at the U of MN School of Public Health Haz Mat training for more information.

16 hour mold remediation course was held at U of MN Minneapolis Campus from 8AM to 5PM April 23 and April 24th, 2012.  The class was at capacity. Instructors were Troy Blanchard, Mike Buck, Neil Carlson and Sean Gabor. 

Epicoccum spp.

Another common indoor and outdoor fungal organism is Epicoccum spp.  This organism can be identified both in culture and through visual observation of a spore trace on an Air-o-cell cassette.

Growth in culture can be a bit problematic as it takes more than 7 days for the spores to be produced.  Growth is better on PDA and MEA than DG-18.  The color is variable from yellow and black to orange and black.

It is commonly found in carpet dust and deposited on elevated surfaces in offices.
 


Epiccoccum spp. in culuture - N. Carlson

Epicocum spp. spores at various stages of growth in culture - N. Carlson

Single Epicoccum spp. spore N. Carlson

Alternaria spp.

I am beginning a series on the most common fungi identified during the course of indoor air fungal investigations.

The organism Alternaria spp. is a common leaf decay fungi with higher outdoor numbers in the late summer through fall.  The outdoor numbers drop dramatically after the first snow fall and typically remain low throughout the winter. 

The organism is easily identified on a spore trap sampler such as an Air-o-Cell.  It will also grow well on PDA (Potato Dextrose Agar), MEA (Malt Extract Agar) and in most cases DG-18 (Dichloran Glycerol Agar) with incubation at 25 degrees C.

It is often a cause of seasonal allergies.  Because of its relatively large size it will deposit in the upper respiratory tract.  I have found it growing on window ledges in buildings and on sheet rock walls.  The spores are commonly deposited on dusty surfaces and floors.   The surface deposition levels are often greater in homes and offices with open windows.

Alternaria spp. line drawings - N. Carlson

 

Alternaria spp. growth in culture.  (42.5 microns long) - N. Carlson

Alternaria spp. spores at various stages of growth N. Carlson

Typical Alternaria spp. growth in culture N. Carlson

 

 

Alternaria spp. taken from Air-o-cell cassette (30 microns) N. Carlson

Alternaria spp. video by the IAQ network

New England Compounding Center in the news

 A NY Times article  FDA details Contamination Found at Pharmacy, provides additional information about conditions in the pharmacy. 

Jennifer Frazer from Scientific American interviewed Glen Roberts a retired Medical Mycologist from the Mayo Clinic  on Exserohilum rostratum.  This fungal plant pathogen was found as a contaminant in the steroids injected into humans.

Clean room particle counts listed for various clean room classification.

Update from the Washington Post notes that other compounding centers in the US have had problems.  At least one, the Massachusetts branch of the Central Admixture Pharmacy Services is  under current investigation. 

The Huffington Post reported that the FDA wanted to close the pharmacy down in 2003.  The deferred to local Massachusetts authorities to resolve the situation.

CBS6 Albany November 6, 2012 90 people report symptoms - 1 minute

CDC initial summary of cases October, 2017 - 4 min.