Gram Positive Rods I Flashcards by Joel Glotfelty

What are the 4 major classes of Gram positive rods?

Corynebacteria, Bacillus, Listeria Monocytogenes, and Clostridium

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What is an example of Corynebacteria?

C. Diptheriae

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What are two examples of Bacillus?

Bacillus anthracis and Bacillus cereus

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What are the four types of clostridium?

C. Perfringens, C. Botulinum, C tetani, and C. difficile

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A patient presents with pain on swallowing and a heavy snoring inspiratory sound occurring in coma or deep sleep, sometimes due to obstruction of the larynx or upper airways. This is likely

Corynebacterium diphtheriae

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Rare on account of wide vaccination

-Humans are the only reservoir

Diptheriae

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Release an exotoxin composed of fragments A and B

Diptheriae

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Facilitates delivery of A toxin to cell interior

B toxin

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ADP-ribosylates the elongation factor EF-2

A toxin

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ADP-R::EF-2 is then inactivated; peptide elongation stops, and the

Cell dies

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Diptheriae toxin binds to host cell membrane proteins

CD-9 and Heparin-binding EGF

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Causes infection of the throat and nasopharynx andcervical adenopathy

Diptheriae

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With diptheriae, a dense gray debris layer of cell debris forms the

Pseudomembrane

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Cardiac and neurologic toxicities can occur due to systemic toxin

Diptheriae

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With diptheriae toxin, the cutaneous disease begins as erythematous pustule, which breaks down to form an ulcer covered with

Grey membrane

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Which medium do we use for identification of diptheriae?

Tinsdale’s agar

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Added to the Tinsdale’s agar to inhibit other flora

Potassium Tellurite

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When cultured, diptheriae organisms produce

Black colonies with halos

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Means “club-shaped”

Coryneform

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A hyper-immune antiserum that neutralizes circulating toxin

Diptheria anti-toxin

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10% of individuals inoculated against diptheria toxin get

Serum sickness

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The diptheria A toxin targets

EF-2

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Club-shaped, Gram (+); black on Tinsdale agar with potassium tellurite

Diptheria

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A Gram stain showed pleomorphic short gram positive rods and coccobacilli, which exhibited a characteristic tumbling motility in hanging drop preparation. This is

Listeria monocytogenes

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The only monocytogenes species that infects humans - usually food borne - especially poultry

Listeria monocytogenes

Phagocytosed listeria bacteria escape vacuole via a

Membrane-damaging toxin

Reorganizes actin to create filament tail, pushing the bacterium to allow contact with adjacent cells

Diptheria

What is the major virulence factor for listeria?

Listeriolysin O

Most common clinical manifestation is diarrhea w/ fever, N/V

Lysteria

Pregnant women infected with lysteria present with "flu-like" symptoms and then have a

Pre-term delivery

To identify lysteria, we use a blood agar. A positive test will show a small

B-hemolytic colony with blue-green sheen

Aerobic and facultatively aerobic; non-spore-forming -Distinguished from streptococci by morphology, tumbling motility on LM in hanging drop and production of catalase

Lysteria

What is a characteristic of lysteria in a semi-solid nutrient agar?

Umbrella motility

How do we treat lysteria?

Ampicillin with a short course of gentamicin for synergy with a serious infection

Lysteria travels cell to cell via a

Host actin

Lysteria are characterized by tumbling motility and are

Catalase (+)

Self-limited diarrheal illness or lethal meningitis

Lysteria

Enzootic disease of world-wide occurrence (sheep, goats, etc) -Transmitted to humans by contaminated dust or contact with animal products (wool-sorter’s disease)

Bacillus Anthracis

Has an anti-phagocytic capsule that is essential for full virulence

Bacillus anthracis

Produces 3 lethal exotoxins encoded by plasmids

Bacillus anthracis

Bacillus anthracis has an adenylate cyclase that increases cAMP. This is called the

Edema factor

95% of human cases are cutaneous:painless, swollen pustule with black eschar= “malignant pustule”

Bacillus anthracis

Can occur in 20% of people with bacillus anthracis

Sepsis

Inhalation of bacillus anthracis spores can lead to -100% mortality if not treated

Hemorrhagic lymphadenitis

Blunt ended bacilli commonly in chains-“Bamboo” -Form endospores-oval and centrally located; non-motile

Bacillus anthracis

Blood agar culture of bacillus anthracis is non-hemolytic with

Comma shape

Aerobically, bacillus anthracis are

Facultative or strictly aerobic

One of the largest pathogenic bacteria -Gram +'ve, rod shaped, non-motile and non acid-fast

Bacillus anthracis

Which three medications can be used to treat cutaneous anthrax?

Doxycycline, ciproflaxin, and erythromycin

Which two medications can be used for the inhalation of anthrax?

Ciproflaxin + Clindamycin

Acquired via break in the skin or via inhalation (wool-sorters or weaponization)

Anthrax

What are the two key words for anthrax?

Bamboo stick appearance and "Comma-shaped"

Intoxication rather than infection - foodborne illness - emetic form associated with fried rice

Bacillus Cereus

Anaerobic, gram positive rods –Inhibited or damaged by oxygen

Clostridia

Spore-forming and mostly motile

Clostridia

Clostridia synthesizes potent exotoxins. What are three examples of these exotoxins?

Botulism, Tetanus, and Gas gangrene

Characterized by crepitus, i.e. air in soft tissue

Clostridium perfringens

Part of the normal flora of the large intestine, skin, and vagina -Spores are found in the soil

Clostridium perfringens

Secretes exotoxins, enterotoxins and hydrolytic enzymes

Clostridium perfringens

α Toxin (phospholipase C) lyses ECs, WBCs, RBCs, and platelets are the

Exotoxins

Affect intestinal function, alter the cell membrane, disrupt ion transport, and leads to loss of fluid and proteins -heat resistant

Enterotoxin of Clostridium perfringens

Occurs when spores are introduced to soft tissue; fermentation of tissue CHO yields gas and rapidly spreading infection -from Perfringens infection

Myonecrosis

Food poisoning: no fever; N/D abd pain 8-18H after eating; self-limited. These are symptoms of

Clostridium perfringens infection

Clostridium perfringens can lead to a rare necrotizing bowel disease called

Enteritis necroticans

Clostridial endometritis is a complication of incomplete abortion that can be caused by

Clostridium Perfringens infection

Large,rod-shaped; non motile, gram + rods

Clostridium perfringens

Clostridium perfringens is cultured anaerobically on blood agar.. It grows rapidly and has unique

Double zone hemolysis

Early aggressive surgical treatment with debridement of devitalized tissue and hyperbaric oxygen therapy, are treatments for

Clostridium perfringens infection

Piperacillin-tazobactamor ticaricillin-clavulanatePLUS clindamyin are also used to treat

Clostridium perfringens

The minimum lethal dose of botulinum toxin is

0.0003 mcg/kg

One gram of aerosolized botulinum toxin can kill

1.5 million people

Found worldwide in soil and aquatic sediments -spores frequently contaminate vegetables and meat

Clostridium botulinum

In a strictly anaerobic environment at neutral or basic pH, organisms germinates and exotoxin produced

Clostridium botulinum

Human disease caused by types A, B and E producing neurotoxic exotoxin

Botulinum

In botulinum, the toxin is cleaved in axon terminals and the light chain blocks

Acetylcholine release at synapse

The botulinum toxin is active at

Motor neuron endplates

What is the result of botulinum toxin?

Flaccid paralysis

Classic presentation: food poisoning, difficulty focusing vision, swallowing (CN function), and shows no fever or sepsis -Caused by TOXIN ONLY

Botulinum

With botulinum infection, progressive paralysis leads to

Respiratory failure

The most common form of botulinum infection in the US/ -colonization of the large intestine leading to constipation and lethargy

Infant botulism

Characterized by the absence of fever and symmetric neurologic deficits

Botulism

What are the three forms of symmetric neurologic deficits seen in botulism?

Cranial nerve palsy, descending weakness, and respiratory arrest

Besides blurred vision, there are no sensory deficit associated with

Botulinism

If isolated from food, stool, or a sterile site. We detect botulinum with a standard

Anaerobic identification

Heptavalent (A-G) horse botulinum immune serum (BIG) or BabyBIG(human serum) are two forms of

Immediate anti-toxin

Infection from botulinum never results in

Immunity

Single gene product (tetanospasm) cleaved into A and B fragments -B fragments delivers A chain to neuron cytoplasm

Tetanus

Blocks neurotransmitter release at inhibitory synapsescausing severe prolonged muscle spasms

The "A" toxin

The resulting symptoms from the A fragment are due to the A fragment blocking

GABA or Glycine release

“A fragment” cleaves synaptobrevin which abolishes

Neurotransmitter release

Has an incubation period from 4 days to several weeks

Tetanus

Presents as spastic paralysis precipitated by

External stimulus

Early stages of tetanus affect jaw muscles, which can result in

Lock Jaw

C. Tetani has a characteristic morphology. What is it?

Racquet shaped bacillus

Aggressive NOSOCOMIAL pathogen -Greater than 500K cases per year; 60% health care associated

C. Difficile

C. difficile bacteria are not

Invasive

Produce Toxin A and Toxin B

C. Difficile

C. difficile damages epithelial cells, producing

Pseudomembranes

C. difficile toxins glucosylate and INACTIVATE

Rho family proteins

Altered lower intestine flora, due to antimicrobial use, allows proliferation of

C. Difficile in the colon