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Veterinary Bacteriology and Mycology

PJL:2010

The course : 5 credits (Mummy)

5 people – A first!!!

Lecturers:

Dr. Mike Collins, Dr. Byeonghwa Jeon

Dr. Jeff Lewis, Dr. Anne Muckle

Lab and Lecture Support: Survival

Batrice Dsprs

Semester Summary - see handout

Lecture, Lab, Exam details, location

Lecturer contact information

PJL:2010

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Overview/Morphology/Structure/Jargon

General Features

Domain Bacteria Proteobacteria

Spirochaetes

Firmicutes

Actinobacteria

No nuclear membrane

Generally 1 chromosome

Extrachromosomal DNA

Oil- immersion (1000x) Cocci : ~ 0.5 – 1.5

Rods: ~

Spirochaetes : 0.5 x 10-20 m

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http://www.cdc.gov/ncidod/eid/vol4no3/relmang.htm

Firmicutes, Actinobacteria

Bacterial Cell Morphology

Cocci – easy!

Rods – still okay!

Straight

Curved

Branching

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Bacterial Cell Morphology

Spiral/coiled pas de problme!

Variations - Yikes !!

Coccobacillus A short rod or oval cocci?

Pleiomorphic Corynebacteria

Mycoplasma’s

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Overview of Bacterial Envelope Structure

Why is Envelope important ?

For the bug: Facilitates a “controlled”

interaction with environment (including host)

For us: Important diagnostic tool :

Gram-stain reaction

Indicator of susceptibility to chemotherapeutic control

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Rhodococcus equi, gram-positive

Proteus mirabilis , gram-negative

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Gram-stain variations

“Old” or anaerobic Gram-positives can appear gram-negative

Gram-variable organisms

“Acid-fast” organisms

Mycobacterium spp.

Spirochaetes are gram-

negative but stain poorly - silver stain to visualize

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G-variable

Classic Bacterial Envelopes

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Lipopolysaccharide (LPS)

Asymmetrical Outer Membrane (OM)

selectively permeable barrier

Endotoxin or Lipid A (pyrexia, DIC, death) Induces cytokines associated with pyrexia, shock and the acute

phase response

TNF , IL-1, IL-6 and IL-8

Long variants can prevent complement fixation

O-antigen is species-specific serological (diagnostic) target

can serve as bacteriophage receptor

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Corynebacterium-Nocardia-Mycobacterium Group

Gram +ves with a “Gram-negative like” OM

NO LPS

Mycolic acid

+/- porin-like OMPs

Niederweis et. al. , 2010

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Figure 3: Corynebacterium-Nocardia-Mycobacterium

Group Envelope

Capsule

Inner

Membrane

Peptidoglycan

With arabinose

and galactose

Mycolic acid rich

Outer-membrane

Mycolic acids

Porin-like proteins?

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Miscellaneous – but still important

Capsule (K-Antigen) – (Slime layer)

Polysaccharide/polypeptide, antiphagocytic, colonization

Antibodies against capsule can confer protection

Flagella (motility) : H-Antigen

“axial filaments” or periplasmic flagella in spirochaetes

not on medically impt. cocci

infrequently in Gram-+ves or bugs with capsules

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Miscellaneous cont’d

Adhesins (F-antigen)

filamentous (pilus) and nonfilamentous (nonpilus) types

Fimbriae (or pili) are filamentous types of adhesins that facilitate adhesion (attachment) to host cells (typically mucosal)

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Miscellaneous cont’d

S-Layer Rigid crystalline lattice structure External to cell wall and OM (Gram -

negatives) Adhesin, antiphagocytic, receptor for

bacteriophage Campylobacter fetus, Clostridium tetani

Spores Resistant, thick walled, produced under

adverse environmental conditions or during the later stages of growth

Spore location within parent cell can aid in i.d.

Clostridium and Bacillus spp.

Terminology – see next page

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Basic Terminology

Obligate - absolute requirement for growth ie. obligate intracellular pathogen requires a host/eukaryotic cell to replicate - Chlamydia spp.

Aerophilic - air loving ; Capnophilic - CO2 loving

Microaerophilic- preference for less than atmospheric levels of oxygen (~6%) to grow (some Actinomyces and Campylobacter spp.).

Obligate anaerobic - cannot grow in presence of oxygen - Clostridium spp., Prevotella spp., Dichelobacter nodosus, and Fusobacterium spp., etc..

Facultative anaerobe - can grow in the presence or absence of oxygen (better in air).

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Endospore - spores produced by Clostridium and Bacillus spp. - typically when deprived of nutrients

Subspecies - species subdivision based on small but consistent differences.

Strain - is a descendant (clone) of a single isolate. The original pure culture isolate from which the strain was described is generally deemed the Type Strain.

Biovar - Strain with special/unique biochemical or physiological properties.

Serovar - Strain with distinctive antigenic properties.

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Basic Terminology