chapter 19: gram positive bacilli

three general groups

1. endospore formers

2. non endospore formers

3. irregular shaped and staining properties

bacillus anthracis

anthrax

• when spores enter the body

• develop under all condistion

bacillus anthracis found where

soil, domestic and wild animals

types of bacillus anthracis

1. cutaneous: spores enter through skin

2. pulmonary: inhalation of spores

3. gastrointestinal: ingested spores

4. injection: in heroin users in north europe

clostridium perfringens found in

• spores found in soil, human and animal intestine

• common in raw meet and poultry

clostridium perfringens causes

1. food poisoning

2. gas gangrene

food poisoning

• outbreaks linked from hospitals or foods where food is kept warm for a long time

• enterotoxins: cause diarrhea

gas gangrene pathology

• not invasive, needs damage tissues and anaerobic conditions

• exotoxins: released caused much of damage gangrene

• fermentation of carbs cause gas and tissue destruction

clostridium tetani location

soil and Gi tract of animals

• common w/ geriatric patients, drug abusers and neonates

pathology of clostridium tetani

cause tetanus/ lock jaw

• spores enter through puncture wounds, burns, frostbite, etc

• need anaerobic environment

• tetanospasmin

• death by paralysis of respiratory muscles

tetanospasmin

neurotoxin block release of acetylcholine used in muscular contraction inhibition

treatment for clostridium tetani

antitoxin therapy

• inactivate circulating toxin

muscle relaxants

• penicillin or tetracycline

C. Diff location

• normal resident of colon

C diff pathology

antibiotic killing other bacteria which makes C. Diff grow

• dysbiosis

cause: antibiotic associated colitis

• enterotoxins, diarrhea

clostridium botulinum

• spore forming, anaerobe

• found in soil and water, canned food

• cause botulism

pathogenesis of botulism

• spores present on food due to improper handling

• anaerobic conditions

• botulin is released

botulin toxin

blocks acetylcholine necessary for contractions

• symptoms: flaccid paralysis

• death: respiratory failure

infant botulism

ingested spores that germinate and release toxin

• flaccid paralysis

listeria monocytogenes

• non spore forming gram positive

• 1-4 flagella w/ no capsules

• resist: cold, heat, salt, pH and bile

listeria monocytogenes virulence

indue phagocytosis and avoids humoral immune system

listeria monocytogenes pathology

• reservoir is soil, water and animal intestine

• contaminate food

• listeriosis

listeriosis

• dairy and poultry meat

epidemiology of listeria monocytogenes

• patients, fetuses, neonates

corynebacterium diphtheriae epidemiology

• reservoir of healthy carriers

• cases occur in non immunized children

• acquired from respiratory droplets

corynebacterium diphtheriae pathology

1. local infection

2. diptherotoxin and toxemia

local infection

upper respiratory tract inflammation

• sore throat, vomit, swollen lymph nodes

• cutaneous diphtheria as ulcers is possible

diptherotoxin production and toxemia

• pseudomembrane formation from inflammation and excess fluid across pharynx can cause asphyxiation

• toxin absorbed into blood targets heart and nerves

mycobacteria characteristics

• gram + irregular bacilli

• acid fast

• strict aerobes

• catalase

• mycolic acids and unique peptodoglycan

mycobacterium tuberculosis

• no exotoxins or enzymes

• tubercle bacillus

virulence factors of mycobacterium tuberculosis

• complex waxes

• cord factor

prevent destruction by lysosomes or macrophages

tuberculosis epidemiology

• improper health

• 15 mil carries in the US

• very resistant

• transmitted by airborne droplets

primary TB

• ID: 10

• multiple intracellularly

• after 3-4 weeks form tubercles

tubercles

granulomas consist of central core containing bacilli surrounded by WBC

secondary TB

• reactivation of bacilli

• tubercles expand and drain into bronchial tubes and upper respiratory tract

• 60% mortality rate

extrapulmonary TB

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

mantoux test

injection of PPD

• look for induration: red wheal to form

• size of wheal indicates result

interferon-gamma release assays

blood test for TB detection

• used when there is a previous vaccine or lack of time

types of diagnosis for tuberculosis

1. in vivo

2. x rays

3. identification of acid fast bacilli

4. culture isolation and biochemical testing

mycobacterium leprae

• strict parasite

• multiples in host cells in large packets (gobi)

• cause leprosy: beings in skin moves to nerves

epidemiology and transmission of leprosy

• transmission not verified

• not virulent its based on health and living conditions

course of infection for leprosy

• weak macrophage or slow T cell response: wont kill bacillus

• grow slow in schwann and macrophages

tuberculoid

shallow lesions damage nerves

• loss of pain reception

lepromatous

deep nodular infection

• face and extremities disfigurement