Lecture 10. Aerobic Gram-Positive Bacilli

Spore forming

Produce endospores for survival in extreme conditions

Non-Spore forming

Do not produce spores, often found as part of normal flora or as opportunistic pathogens

Gram-Positive Bacilli are:

• Rod shaped

• Aerobic

Which spore-forming species of Bacillus resembles bamboo rods?

Bacillus anthracis

Bacillus anthracis causes

Anthrax

Forms non-hemolytic, large, flat gray-white colonies with a “ground glass” appearance. Also has a unique “medusa head" appearance on media

Bacillus anthracis

Has a frosted glass or matte appearance on media

Bacillus cereus

Bacillus cereus produces spores and causes foodborne illness

True

Corynebacterium diphtheriae

Causes diphtheria, a potentially fatal respiratory illness

Microscopically, Corynebacterium diphtheriae

Appears as club-shaped or V-shaped (pallisades or Chinese letters)

Corynebacterium diphtheriae grows well on

Cystine-Tellurite Blood Agar (CTBA) or Loeffler's medium

On CTBA (or Loeffler's medium), Corynebacterium diphtheriae gives off what kind of appearance?

Black or grayish-black colonies due to the reduction of tellurite

Non-diphtheritic corynebacteria are often referred to as

Diphtheroids

Listeria monocytogenes is known for causing

Listeriosis, a serious foodborne illness

Listeria monocytogenes is a ______ ______ pathogen

Facultative intracellular pathogen

Facultative intracellular pathogens have the ability to

Live inside and outside host cells, helps evade the immune system

Has a “tumbling motility" at room temp due to its flagella but is non motile at 37 degrees celsius

Listeria monocytogenes

Although Listeria monocytogenes can grow well at room temperature (30-37 degrees Celsius), it can also grow at:

Refrigeration temps

Listeria monocytogenes can form spores

False, L. monocytogenes cannot form spores

Zoonotic pathogen

Affects both animals and humans

Which non-spore forming bacterial species mostly affects handlers of animals/animal products, ex: butchers, farmers, veterinarians & fishermen?

Erysipelothrix rhusiopathiae

A localized skin infection of the species Erysipelothrix rhusiopathiae in humans is called

Erysipeloid

Which non-spore forming species helps maintain balance of normal flora of GI tract, oral cavity, and vaginal tract? This species also is used in probiotics

Lactobacillus Species

Lactobacillus species are _____ anaerobes

Aerotolerant

• Partially acid-fast

• Resembles fungi due to branching morphology

Nocardia species

Nocardiosis

Pulmonary, cutaneous or disseminated infections, including CNS involvement

Colonies of Nocardia species typically have a:

• Chalky, white or orange color & have a dry, crumbly appearace

• “breadcrumb-like"

What is the most clinically significant of the Rhodococcus species?

Rhodococcus equi, is partially acid-fast

On media, Rhodococcus equi gives off:

• Smooth, mucoid, and salmon-pink or coral in color

• Form creamy, wet-looking colonies due to the production of polysaccharides