Microbiology and immunology midterm 2

What type of gram Bacilli is the spore forming rods

gram postive

What are the two types of spore forming rods

Bacillus and Clostridium

What type of toxins do they release

potent exotoxins that cause disease

What is Bacillus anthracis the causative agent of

Anthrax

What is unique about Bacillus anthracis

it has a unique protein capsule that gives it extra protection from complement proteins

What condition does it grow in 

in aerobic growth conditions and the spores are very stable, resistant to heat 

what do the spores do

they germinate and can cause clinical manifestation

how do humans come in contact with it

they are exposed to spores usually through contact with animals or soil and inhaling those spores

How many plasmids does it have

2( PxO1 and pXO2)

Where is the conditions found for them to grow

in the respiratory system

What are the three seperate proteins the exotoxin is composed of

edema factor(EE)

Protective antigen

Lethal Factor

separately proteins are not toxic, but combined they are lethal

which encoded plasmid encodes for capsule genes 

pXO2 but both plasmids required for virulence 

Is there a treatment and vaccine for this virus

yes for both and rapid treatment is essential

Which Bacci causes food poisoning when spores enter food product when not heated properly

Bacillus cereus

What type of exotoxin is responsible for illness

Enterotoxin

What are the two types of enterotoxins it can produce 

Heat labile: nausea, abdominal pain, diarrhea Heat stable: severe nausea and vomiting, short incubation 

Is there a treatment and vaccine and are they useful?

Yes there is a treatment but it is useless against preformed toxins

and there is no vaccine

What differentiates Clostridium Bacilli from other spore forming bacilli

it is an Anaerobic spore- forming bacilli

What illnesses does it cause 

Botulism, tetanus, gas gangrene and pseudomembranous colitis 

What are the different types of Clostridium

• Clostridium botulinum

• Clostridium tetani

• Clostridium perfringens

• Clostridium difficile

what causes Clostridium botulinum

rapidly fatal food poisoning from lethal neurotoxin

what does this neurotoxin do

it blocks ach release in autonomic system and causes bilateral cranial nerve palsies, double vision, Afebrils, trouble swallowing

What else does it do

causes respiratory paralysis which leads to death 

is there a treatment

yes and properly cooking destroys spores

Infant botulism

honey contamination with spores

they germinate and bacteria colonizes intestine leads to floppy baby syndrome 

What causes Clostridium tetani

stepping in anything with spores punctures skin and wound would provide anaerobic environment

What type of toxin does it release

exotoxin: tetanospasmin

What are the clinical manifestations

➢Sustained contraction of skeletal muscles

➢Severe muscle spasms (lock jaw); high

mortality at this stage

tetanus 

is there a vaccine/ treatment 

yes ➢ Booster (inactivated toxoid) given every 10 years

What does Clostridium perfringens cause

Gas gangrene

What are the two classes of infection 

➢ 2 classes of infection:

(i) Wound infection/cellulitis

-necrotic skin exposed to bacteria, damage to local

tissues; skin feels moist, spongy, with ‘crackly’ pockets

(ii) Clostridial myonecrosis

-bacteria inoculated from trauma into muscles; exotoxin

secretion destroys adjacent muscles; as muscles degrade get black fluid excreted from skin

-FATAL unless treated with oxygen, antibiotics

(penicillin) and removal of damaged tissue

is there a treatment 

yes but FATAL unless treated with oxygen, antibiotics (penicillin) and removal of damaged tissue

what can cause Clostridium difficile

Causes antibiotic-associated pseudomembranous colitis

➢ Overuse of broad-spectrum antibiotics destroys normal intestinal flora

➢ Infects colon and releases exotoxins

➢ Toxin A: diarrhea

➢ Toxin B: cytotoxic to colon cells

what are some symptoms

Symptoms: severe diarrhea, abdominal cramping, fever

➢ Possible cause of diarrhea in patients on antibiotics

what are some treatments 

treatment

➢discontinue antibiotic treatment

What are the two non spore forming gram positive rods

• Listeria monocytogenes

• Corynebacterium diptheriae

What is Listeria monocytogenes the causative agent of

Causative agent of listeriosis; immunocompromised are at high risk

Where is it found

➢ Found in foods such as soft cheeses, unpasteurized milk, cold cuts, pâté

What type of temperature does it survive in? 

PSYCHROPHILE survives in refrigerator

what are some of its symptoms and is there a treatment

➢General malaise, diarrhea, meningitis, septicaemia,still-birth/abortions

➢ Facultative intracellular aerobe

➢ Crosses 3 protective barriers (blood-brain, GI and feto-placental)

➢ Treatment: ampicillin or trimethoprim-sulfamethoxazole

What is Corynebacterium diptheriae the causative agent of 

Causative agent of diphtheria

where does it colonize 

Colonization of pharynx and release of exotoxins into bloodstream

➢ Exotoxin damages heart and neural cells

is there a treatment and vaccine 

yes and the vaccine is (DPT vaccine

What are the classes of gram negative bacilli

Enterics- all have endotoxins 

where are they found 

Found as part of normal intestinal flora BUT can also cause disease

Organisms are divided into groups based on biochemical and antigenic properties

what are the three types of surface antigens that call gram negative bacilli will always have

Variable O-antigen: outermost layer of LPS

• Changes between enterics

• K-antigen: covers the O-antigen- protein capsule

• H-antigen: flagellar sub-unit

• Only in motile bacteria

what are some diseases caused by enterics

Cause diarrhoea with various complications and other infections

• EXOTOXIN release causes diarrhoea; ENTEROTOXIN causes fluid/electrolyte loss

• Watery diarrhoea, NO FEVER

• Vibrio cholera

 2) Diarrhea with intestinal cell invasion

• Bacterial virulence factors allow binding and invasion of cells bloody stools

• Toxin release destroys cells

• Fever response

• Shigella,

3) Diarrhea with invasion of lymph nodes and bloodstream

• Abdominal pain with diarrhoea containing white and red cells

• Fever, headache, increased white cell counts

what are the two types of Salmonellae

➢ Enterocolitis (tummy problems):

➢ S. enterica serovar Enteritidis

➢ S. enterica serovar Typhimurium

➢ Typhoid (enteric) fever:

➢ S. enterica serovar Typhi

➢ S. enterica serovar Paratyphi

S. enterica serovar Enteritidis

Enterocolitis

• Pathogenesis depends on:

• Dose of ingested organism (min 105)

• Immune status of host

• Virulence of strain

what are the symptoms of Entercolitis 

Symptoms

• Nausea, vomiting, profuse diarrhoea, abdominal pain

• Fever, chills, headache, myalgia

• 2-3 days recovery

• Septicaemia Rare

• Use stool culture for lab diagnosis

S. enterica serovar Enteritidis

Enterocolitis

• Ingestion of contaminated food →

• Poultry, eggs, meat and milk

• Person to person spread

• Most cases occur at home

• Under-reported and undiagnosed

• Antibiotics NOT RECOMMENDED WHY?- some strains grow better with antibiotics