Chapter 19: Gram Positive Bacilli of Medical Importance

What are the three general groups gram-positive bacilli are split up into:

1. endospore formers

2. non-endospre formers

3. irregular shaped and staining properties

What are the two sporeformers:

1. Bacillus

2. Clostridium

What are the three non-spreformers:

1. mycobacterium

2. listeria monocytogenes

3. corynebacterium

Sporulation

from the vegetative stage —> to a spore

Germination

from a spore —> into the vegetative stage

found naturally in soil and affects domestic and wild animals around the world; not communicable (has to be direct) when spores get into the body

Bacillus Anthracis

What are the 4 types of anthrax:

1. Cutaneous

2. Pulmonary

3. Gastrointestinal

4. Injection

Spores enter through skin, black sores = eschar, least dangerous

cutaneous

inhalation of spores

pulmonary

ingested spores

gastriointestinals

in heroine injecting users in Norther Europe

injection

• spores found in soil and the intestines of humans and animals

• contaminant of raw meat and poultry that have not been cooked thoroughly

Clostridium

What are the two types of clostridium perfringenes

“food poisoning” and gas gangrene

What are the different types of clostridium

• perfringens

• tetani

• clostridioides difficile

• botulinum

Outbreaks are linked to cafeteria syle institutions, incubation period 6-24 hrs, enterotoxins cause diarrhea

food poisoning caused by Clostridium perfringens

Clostridium perfringes most frequent clostridia involved in soft tissue and wound infections causing ___________.

gas gangrene

requires damaged and dead tissue and anaerobic conditions, exotoxins released cause most of the gas, to come from a lot of wounds, ex. surgical incision

Gas gangrene

common resident of soil and GI tracts of animals, causes tetanus or lockjaw, most common in geriatric patients and drug users

clostridium tetani - tetanus

For _________-, spores enter through wounds, burns, umbilical stumps, frostbite, crushed body parts, etc.

tetanus

neurotoxin causes paralysis by binding to motor nerve endings, block the release of neurotransmitter for muscular contraction inhibition, muscles contract uncontrollably

tetanospasmin

What are treatments for tetanus

• aimed at deterring toxemia and infection

• controls infection with penicillin or tetracycline = muscle relaxants

• vaccine

Clostridioides difficile

a resident of the colon, noninvasive, treatment = antibiotics kills other bacteria

What causes antibiotic-associated colitis

Clostridioides difficile

Clostridioides difficile

produces enterotoxins and the major cause of diarrhea

C. difficile infection can result from gastrointestinal ______

dysbiosis

Dysbiosis

the disruption of the composition of resident microbiota —> that can lead to c. difficile growth

Clostridium botulinum

inhabits soil and water, rare BUT SEVERE intoxication from HOME CANNED FOOD

Botulism

intoxication associated with inadequate food preservation

Botulin toxin

carried to neuromuscular junctions and blocks the release of acetylcholine, necessary for muscle contraction to occur

infant botulism

caused by ingested spores that germinate and release toxins, flaccid paralysis

wound botulism

spores enter the wound and cause symptoms similar to food bourne botulism

flaccid paralysis results from which infection?

botulinum

What are gram-positive regular non-spore forming bacilli

listeria monocytogenes

gram positive regular meaning —→

stain uniformly and do not assume pleomorphic shapes

listeria monocytogenes main characteristics

non spore forming gram-positive, resistance to cold, heat, salt, pH, and bile,

listeria monocytogenes

ability to replicate in the cytoplasm of host cells after inducing phagocytosis avoids the humoral immune system

Listeria monocytogenes

inhabits in soil, water, and animal intestines, can contaminate foods, and grow during refrigeration

listeriosis

most cases associated with dairy products, poultry, and meat

What are the two gram-positive irregular non spore forming bacilli

1. corynebacterium

2. mycobacterium

when it says gram positive irregular, it means that

pleomorphic, stain unevenly

C. Diptheriae

inhabits in healthy carriers, occur in nonimmunized children living in crowded, unsanitary conditions, acquired by respiratory droplets from carries

What are the two stages of disease for C. Diptheriae

1. local infection

2. diptherotoxin production and toxemia

Local infection

upper respiratory tract inflammation, cutaneous diphtheria manifesting as ulcers is also possible

Diptherotoxin production and toxemia

pseudomembrane formation form inflammation and excess fluid across the pharynx can cause asphyxiation

• toxin absorbed into the blood from the throat can target organs

Which infection typically results for contaminated food?

listeria monocytogenes

Mycobacteria

acid-fast bacilli

mycobacteria

gram-positive irregular bacilli, acid-fast staining, strobes, catalase, possesses Mycolic acids, grows slowly

mycobacterium tuberculosis

tubercle bacillus produces no exotoxins or enzymes that contribute to infections

Primary TB

ID: 10 cells, multiply intracellularly, forming tubercles, and granulomas, consisting of a central core containing bacilli surrounded by WBC - tubercle

Secondary TB

reactivation of bacilli can occur —> tubercles expand and drain into the bronchial tubes and upper respiratory tract, 60% mortality rate

extrapulmonary TB

during secondary TB, bacilli disseminate to regional lymph nodes, kidneys, long bones, genital tract, brain, and meninges

What are the different types of diagnosis for TB

1. vivo or tuberculin testing/ blood test

2. X rays

3. direct identification of acid-fast bacilli in specimen

4. cultural isolation and biochemical testing

Mantoux test - blood testing

local intradermal injection of Purified protein derivative (PPD), look for red wheal to form induration

IGRAS

interferon-gamma release assays

interferon-gamma release assays - blood testing

blood test for detection of TB, positive and negative for the presence of TB bacterial products *used for when a person has been vaccinated

Mycobacterium leprae: the leprosy bacillus

strict parasite, slowest growing of all mycobacterium species, globi = multiplies within host cells in large packets, causes leprosy

leprosy

a chronic disease that begins in the skin and mucous membranes and progresses into nerves, endemic

What are the two forms of infection and disease for leprosy

1. tuberculoid

2. lepromatous

Tuberculoid

asymmetrical, shallow lesions, damages nerves, results in local loss of pain reception

Lepromatous (multibacillary)

a deeply modular infection that causes severe disfigurement of the face and extremities, widespread dissemination

What is NOT a test used to detect TB?

• X rays

• MRI

• blood tests

• Cultivation

• All are test for TB

MRI