Saturday, March 17, 2018

Not so smooth strawberry smoothie

Several day old strawberry smoothie - N. Carlson
Beware of the several day old strawberry smoothie. This one was was a fuzzy gray when it arrived at the kitchen sink.  I took a tease tape, transferred to a slide with some mounting fluid and examined it under a microscope. The organism has characteristics of both Rhizomucor spp. and Rhizopus spp.  With Rhizopus spp. the sporangiophores start at the same location as the rhizoids (root like structure) individual Rhizopus spp. are connected with a non septate stolon perpendicular to the rhizoids. This is similar to the runners that strawberry plants employ.  With Rhizomucor spp. the sporangiophores branch some distance away from the rhizoids. The branching on this sample is some distance from the rhizoids.

The Rhizomucor spp. sporangiospores are usually under 6 microns in diameter with round to slightly oval spores although some are irregularly shaped.  The sporangiospores in this sample are greater than 6 microns and have the characteristic walnut shell shape of a Rhizopus spp. spore. Both of these organisms can cause strawberries to rot.

Rhizopus spp. line drawing - N. Carlson

Rhizopus spp. or Rhizomucor spp.  - 400x - N. Carlson

The branching at the end is more typical of Rhizomucor spp. - 100x

Close-up of sporangiospores  that are more typical of Rhizopus spp. 

Clinical signs for zygomycete exposure (Mucor spp., Rhizopus spp., or Rhizomucor spp.) infection - 4 min.

Friday, March 9, 2018

Tickborne diseases in Minnesota

MDH  tickborne disease stats from 2007 to 2017

The official start of spring in the northern hemisphere is approaching. With the warmer weather families plan outdoor adventures. This past year I gave a talk on tick borne diseases in Minnesota and the surrounding areas. After reviewing the information, it reinforced my conviction to be careful.

Most of the emphasis has been on Lyme disease transmitted by small black legged ticks. There are other diseases. Fortunately, one of the really nasty tick borne diseases  Powassan Virus (CDC) is rare. Unfortunately the effects of this rare illness are really nasty. It can cause swelling of the brain, crushing headaches, and death.  Doctors can only offer palliative care as there is no effective treatment.

There has been controversy surrounding the treatment for chronic Lyme disease.  A reference below lists some of the side effects from these treatments. As a tick may carry more than one disease this may in part explain ongoing symptoms. Continuing to use the antibiotics for Lyme disease would be ineffectual and make the patient susceptible to more side effects.

On a personal note: I was misdiagnosed with Lyme disease in the 1980s when the blood tests were not as accurate.  I ended up going through the course of antibiotics and met my share of marginally competent phlebotomists.  The experience was not pleasant and it was also ineffectual.

Please review the interesting article below on how the decline in the fox population is associated with an increase in Lyme disease.  Other habitat changes that allow deer mice populations to explode also increase the risk for tick disease transmission.

These are a few of the many tips from MDH tick prevention:
  • Apply DEET on skin and use Permethrin on clothing (not skin). 
  • Walk in the center of a trail
  • Tuck light colored pants inside socks.
  • Inspect and remove ticks within 24 hours. 
  • Avoid walking in woody or brushy areas during times of the year where the risk of tick borne disease is high.

Applying DEET and Permethrin MDH - Approximately 3 minutes.

Tick removal - MDH Approximately 1 minute. 

Tickborne disease references:

University of Manitoba - tick removal - 2 min. 

Tuesday, January 30, 2018

Recipe for DG-18 Agar

Fungal growth on DG-18 Agar

The primary organisms on these two DG-18 agar plates include Penicillium spp., Cladosporium spp., Aspergillus spp., and Wallemia spp. 

Our lab uses DG-18 or Dichloran Glycrol agar to grow culturable xerophilic (dry loving) fungi on indoor air and surface samples. This DG-18 agar grows mould or yeast at water activity (aw) less than .85).  The restricted colony growth and the inhibition of the zygomycete fungi on the plate allow for easier identification and counting of mould colonies on the plate. Some water loving moulds like Stachybotrys spp. and Aspergillus fumigatus do not grow well on this media. We often pair plates of MEA (Malt Extract Agar) with the DG-18 agar to capture organisms needing higher water activity.

DG-18 Media Recipe:
  • 172 milliliters (ml) of glycerine
  • 31.5 grams (g) of DG-18 dry powder agar
  • 1000 ml of distilled water
  • 0.1 g of chloramphenicol in 5 ml of 70% ethanol suspension (add after other ingredients are mixed) - This antibiotic limits bacterial growth on the culture plate.  Autoclave the culture plates after identification to limit problems with the development of antibiotic resistance. 
  1. Heat mixture to boiling using stir bar and a hot plate in a covered 2 liter flask. Make sure all media dissolves into solution.  Observe and modify the stir plate temperature to prevent it from boiling over. 
  2. Use insulated gloves to transfer liquid agar solution to an autoclave.
  3. Autoclave  for a 60 minute cycle at 121 C. 
  4. Remove and keep warm in a 60 C incubator. 
  5. Pour out 13.5 ml of agar onto a Rodac plate or 25 ml onto a 100 petri dish on a laminar flow clean bench.  Refrigerate covered in a plastic bag and store for up to 3 months. 

Friday, January 26, 2018

Acrodontium spp.

Acrodontiium spp. on DG-18
The organism, Acrodontium spp. was found to be a laboratory contaminant on culture plates.  The organism is similar to several other organisms.  The colony growth is slow on DG-18 agar with white fluffy restricted growth at 5 days.

Acrodontium spp. 400x (25 microns between 6 and 7)

The lower end of the conidiophore is wider at the base then the conidia producing structure at the tip of the conidiophore.  I identified the organism using the key in the book, The Genera of Hyphomycetes  These spores would not be identifiable to genera on an Air-o-cell cassette sample.

Saturday, December 30, 2017

Illustrated Genera of Imperfect Fungi by Horace Leslie Barnett

As a student, I used an earlier edition of this book for identifying fungi in my mycology class at the University of Minnesota.  The addition of photos in the front of the book are a welcome improvement over the original text.  Multiple similar organisms are pictured on the same page and this helps to differentiate between them for identification.

Link to book: Illustrated Genera of Imperfect Fungi 4th (fourth) Edition by Barnett, Horace Leslie, Hunter, Barry B. published by Amer Phytopathological Society (1998)

The book is useful for both the beginning mycologist focusing on indoor air and the plant pathologist.  The line drawings aide in identification.  The addition of a 10 micron scale to each of the drawings would also make it even more useful. 

This book provides an excellent companion to Identifying Filamentous Fungi and The Genera of Hyphomycetes. 

Hyaline monomorphic fungi Glen Roberts PhD part 4 - 20 min.

Hyaline monomorphic fungi Glen Roberts PhD part 5 - 29 min.

Hyaline monomorphic fungi Glen Roberts PhD part 6 - 13 min.

Identifying Fungi by Guy St. Germain and Richard Summerbell

I have used the lab reference book Identifying Fungi 2nd Edition by Guy St-Germain and Richard Summerbell as the text for a course on indoor air fungal identification taught at the University of Minnesota.  The students like the accessible format with both a textual and visual key at the beginning of the book.  Each organism has a line drawing to scale, a photo of the organism in culture and a photo of the organism under light microscopy. 

The glossary and suggestions media and stains are also helpful.  I have met both of the authors.  Guy St-Germain took a class with me in San Antonio, Texas with the National Laboratory Training Network.  Richard Summerbell taught a section of a fungal identification course in Ottawa, Canada. 

As we've trained staff in our department on fungal identification, this book and the first edition have been the one we've used to get them started to become competent at identifying some of the most common indoor molds on culture. 

Identifying filamentous fungi Glen Roberts - PhD - part one - 24 min. 

Monomorphic fungi Glen Roberts - PhD - part two - 26 min.

Monomorphic fungi Glen Roberts - PhD - part three - 16 min.

Monday, December 25, 2017

The Genera of Hyphomycetes by Keith Seifert and others

The Genera of Hyphomycetes
I recently borrowed a copy of The Genera of Hyphomycetes in the McGrath Library of the St. Paul Campus of the University of Minnesota. This massive tomb of nearly 1,000 pages took over twenty years to complete. There are close to 1,000 line drawings of hyphomycetes classified by spore type.  I ended up using the book to help identify a fungal organism growing on a window ledge.

I had the opportunity to meet the principal author, Keith Seifert, where he was one of several lecturers at a fungal identification workshop in Ottawa, Canada many years ago. At that time his specialty was the genus Fusarium spp. The class was excellent, as was the city and the dining.  During the conference we were able to attend a traveling Renoir portrait exhibit at the local museum. Each painting included historical information about the subject(s).  Of all the paintings in the exhibit, I found the large portrait of Monet painting in his garden to be the most intriguing.

The plants in our gardens survive because mycologists working as plant pathologists quietly do work that reveals the complex often multi-host ecology of these fungal organisms. Medical mycologist work on human disease prevention. In health and safety, we poke around the edges of mycology trying to our best to keep people alive, buildings from rotting, and research on other organisms free from contamination. I very much appreciate the work these authors put into this book to help all of us who search around the edges.

Gentle teasing of the Author Keith Seifert by P. W. Crous and R. A. Samson 2 min.

Importance of Hyphomycete taxonomy - Keith Seifert 17 minutes.

Sunday, November 12, 2017

Identifying moldy fruit in the refrigerator

Moldy black raspberry

Keeping fruit fresh in a refrigerator is a challenge.  These black raspberries became moldy after less than a week in a refrigerator.  Most of the mold on the surface was mycelia without reproductive structures.  I used a clear 3M transparent tease tape and with a 85% lactic acid mixed with fuchsin dye to identify the organism under 400x power.
Low resolution photomicrograph of Botrytis spp.  - N. Carlson

Close up of Botrytis spp. growing on the black raspberries - N. Carlson 

Photomicrograph of Cladosopoium spp. growing on the black raspberries. - N. Carlson

Identifying moldy vegetables in the refrigerator

Moldy red pepper - N. Carlson

With a microscope at home it's fun  to check on what's growing items that have gone way beyond the best by date.  These red peppers were in a closed container for more than a couple weeks.  The primary organisms identified were yeast and the dark colored Cladosporium spp. The Fridge temperature was reading 36 degrees F. or a 2.2 degrees C.

Yeast - N. Carlson
Cladosporium spp. - N. Carlson

Sunday, October 8, 2017

IAQ radio interview with Andrew Streifel U of MN

Andrew Streifel - N. Carlson
I've had the pleasure to work with Andrew Streifel for over 30 years, first as a graduate student and then as a co-worker at the University of Minnesota Department of Environmental Health and Safety.  He is a prolific author of journal articles, an excellent speaker and the go to consultant for hospitals around the world when they are trying to solve a difficult infection control problem.

In the summer of 2017, he was interviewed on IAQ Radio discussing aspects of health care acquired infections, formerly known as nosocomial or hospital acquired infections.  In IAQ Radio Episode 470 Andrew Streifel, he reviewed the major areas of concern including infection sources, sampling methods and case studies of patient infections.

This is a list of just some of the factors mentioned that contribute to health care acquired infections:
  • The clothing worn by guests visiting a patient can be contaminated with spores from the outdoor air.
  • The previous occupant of a patient care room may pass their infection onto the next patient. Therefore, the quality of surface decontamination between patients is critical. 
  • Improper installation of building filters allows outside air to by pass the filters. 
  • A negatively pressurized building can bring in unfiltered air into the patient care area. 
I hope you get a chance to listen to the full interview. It provides many helpful suggestions for investigating health care acquired infections.

Andrew Streifel on IAQ Radio - 1 hour