Neisseria gonorrhoeae



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PROKARYOTES

Neisseria gonorrhoeae

Produce receptors for siderophores of other bacteria to take iron from other bacteria or so that they are able to bind human iron sources

Transposons are responsible for the phase variation of pili antigens, antibodies can no longer recognize the surface

Use type IV pili like a grappling hook to spread to infected tissues

Secrete enzymes that chop secretory IgA into pieces so it no longer works

Venereal transmission is the primary means of transport


Neisseria meningitidis

Produce receptors for siderophores of other bacteria to take iron from other bacteria or so that they are able to bind human iron sources

Primary carrier site is the nasopharynx

Incorporate sialic acid into their capsule polysaccharides to discourage complement activation

When it travels in the bloodstream, it becomes coated with circulating IgA that binds to its antigenic sites. This binding covers up the sites where other Ab molecules, like IgM or IgG, would bind (IgA doesn’t activate complement)



Haemophilus influenzae

Produce receptors for siderophores of other bacteria to take iron from other bacteria or so that they are able to bind human iron sources

Primary carrier site is the nasopharynx

Secrete enzymes that chop secretory IgA into pieces so it no longer works

Carries conjunctivitis, highly contagious, that is usually transmitted from eye to hands, and then hands onto objects



Streptococcus pneumoniae

Undergoes transformation often

Primary carrier site is the nasopharynx

Encapsulated, makes them hard to phagocytize

No spleen makes you more susceptible to infection

Cell wall contains a PAF-like moiety that binds to PAF receptors to trick the cell into uptaking the bacteria

Covers itself with a thick polysaccharide capsule that helps prevent complement components from coming into contact with the teichoic acid on its surface


Some streptococci, on the other hand, protect themselves from opsonization by breaking apart the C3b molecule.

Corynebacterium diphtheriae

Utilizes temperate bacteriophage prophage conversion to make toxins (info is in viral prophage, not bacterial DNA)

NF of the skin

Only makes diphtheria toxin when the organism runs out of iron

Toxin works by disrupting protein synthesis through A-B toxin mechanisms in which the whole toxin molecule is taken into host cells. Acidification releases the A moiety into the cytoplasm

Can form a thick leathery membrane in the throat made up of dead cells

Organisms do not invade the tissue



Salmonella typhimurium

Cause of typhoid fever

Phase variation of flagellin expression occurring in REC- cells

Usually killed off by normal flora

Cover membrane attack complexes with long polysaccharide chains on their outer membranes

Organism can persist in the gall bladder can cause hosts to shed the organisms in their feces and/or urine and thereby infect other people

Fecal/oral transmission



Staphylococcus aureus

Became penicillin resistant and methicillin resistant (MRSA), eventually becoming vancomysin resistant

Part of the USA classification system (main is USA 300)

Has the mec chromosomal cassette

Primary carrier site is the nose

Protein A productionbinds IgG by Fc portion so they are stuck on the org by the wrong end (the one that is supposed to bind to phagocytes)

Catalase production that prevents the oxidative burst pathway by breaking down hydrogen peroxide



Clostridium difficile

Only bacteria to still undergo restriction enzyme identification

Found in the GI tract

Example of an opportunistic pathogen

Common to enter a puncture wound like an ear piercing



Staphylococcus epidermidis

NF of the skin, example of opportunistic pathogen

Propionobacterium acnes

Development of acne because it breaks down oils in the hair follicles to produce bacterial waste products that stimulates the inflammatory response

Streptococcus mutans

Cause of tooth decay and periodontal disease

Helicobacter pylori

Lives in the stomach and is a urease producer that protects itself from the low pH of the stomach

Can persistently infect the stomach and induce gastric inflammation that leads to 9 of 10 cases of ulcers.



Escherichia coli

Found in the GI tract

Women who have recurrent urinary tract infections often have a greater than normal density of receptors for uropathogenic E. coli on their vaginal epithelial cells than women who don’t tend to get UTI’s.

Cover membrane attack complexes with long polysaccharide chains on their outermembranes


Pseudomonas aeruginosa

Gram-negative, opportunistic pathogen that can invade any tissue that is common in moist respiratory machines in hospitals because they like air and moisture

Use type IV pili like a grappling hook to spread to infected tissues

Can cleave C5a, the main anaphylotoxin that calls in neutrophils

When in a host environment in which the phosphate supply is limited, the organism increases production of phospholipase C, which hydrolyzes host cell membrane phospholipids to release phosphate in a utilizable form for them



Bordetella pertussis

Whooping cough

Example of a strict pathogen



Clostridium perfringens

Theta toxin it produces paralyzes PMN’s so they can no longer call for reinforcements

Produces lecithinase that causes gas gangrene which is a membrane disrupting toxin that causes tissue to become soft and destroyed

Also produces collagenase which breaks down collagen and acts sort of like a meat tenderizer so the tissue may look macerated in the case of gas gangrene


Streptococcus pyogenes

Cause of strep throat and can result in rheumatic fever

Non-pili adhesins called protein F that binds to fibronectin on epithelial cells at mucosal surfaces

Gram (+)

Produces Streptolysin O toxin



Listeria monocytogenes

Moves between cells though host actin polarization that propels the bacterium toward the cell surface from another

Yersinia pestis

Prevents macrophage phagocytosis

Also injects macrophages with enzymes that prevent them from producing pro-inflammatory cytokines

Causes plague


Bacillus anthracis

Produces a lethal toxin

Shigella flexneri

Causes bacillary dysentery. It is actually phagocytosed rather easily, but within 15 minutes of being taken up, it produces enzymes that allow it to escape from the phagosome into the cytoplasm and grow

Legionella pneumophila

Cause of Legionnaire’s disease

Have molecules on their own membranes that modify the phagosome membranes so they are no longer compatible with those of lysosomes and can’t fuse properly



Leishmania

Resistant to lysosomal enzymes and secrete enzyme inhibitors that prevent the action of the enzymes

Mycobacterium tuberculosis

Master at living inside macrophages

Uses multiple techniques to do so and causes a slow growing, smouldering infection

Notorious for latency; organism may persist in lungs and then reactivation may cause acute disease


Clostridium botulinum

Produces “bot toxin” that is most potent of all microbial toxins

Vibrio cholera

Makes cholera toxin

Also an AB toxin mechanism but with five B and one A moiety

Leads to massive watery diarrhea


Shigella dysenteriae

AB toxin but not excreted by the bacteria, rather released when the organism is lysed

Causes bacillary dysentery

Toxin cleaves and inactivates the host cell 60S ribosome

Fecal/oral transmission



Clostridium tetani

Tetanus toxin is another AB toxin

Organism rarely moves from the location of the wound but its toxin acts on a distance on the CNS, causing the muscles to be constantly stimulated

Spores of this organism are very common in the soil, and only cause infections when injected into a wound that offers an anaerobic environment.


Borrelia burgdorferi

Can cause chronic arthritis in patients with Lyme disease

EUKARYOTES

Opisthorchis viverrini

Class one Carcinogen in Thailand; parasite found in freshwater

Cryptosporidiosis

Parasite that can get into the host and then is covered by the host cell membrane

Zygomycetes

Opportunistic exogenous mycoses, can be phagocytized, Infection of nasal passages, sinuses, eyes, cranial bones and brain are major clinical problem (very troubling and difficult infection)

Aspergillus

Opportunistic exogenous mycoses, soil and on plants, small conidia form aerosols (spores), can be easily phagocytized

Cryptococcus neoformans

Opportunistic exogenous mycoses, soil and bird droppings, thick polysaccharide capsule to avoid phagocytosis, infection by inhalation

Pneumocystis carinii

Harmlessly present in lungs – can cause pneumonia in compromised patients

Yeast like fungus



Paracoccidioides brasiliensis

Central and South America, asymptomatic infections common, general symptoms similar to histo and blasto…, disseminated disease rare, usually oral, nasal and facial nodular ulcerative lesions and lymphadenopathy

Coccidioides immitis



Southwest US, parts of Mexico, South America, infection usually asymptomatic but mortality of untreated disseminated disease is ca. 50%

Blastomyces dermatitidis

Ohio and Mississippi River valley and Missouri and Arkansas River basins, disease also seen in horses and dogs, similar to histoplasmosis / mimic TB or lung cancer, symptomatic infection common

Histoplasma capsulatum

Ohio and Mississippi River valley, asymptomatic and self limiting (immunocompromised patients are problem), form localized granuloma / can disseminate, can mimic TB

Sporothrix schenckii

Subcutaneous Mycoses, dimorphic, causes sporotrichosis often after a thorn prick, leading to nodules and ulcers at inoculation site and along draining lymphatics

Ringworm or tinea + (location)

Cutaneous Mycoses,

Pityriasis versicolor (Malassezia furfur)

Superficial Mycoses, more common in tropical climates

Tinea nigria

Superficial Mycoses, melanin producing dimorphic fungus in the tropics

Black and White piedra

Superficial Mycoses, hair shaft

Blastomyces

Dimorphic Fungi

Coccidoides

Dimorphic Fungi

Histoplasma

Dimorphic Fungi

Candida

Normal Eukaryotic flora, skin and mucus, can cause thrush, found in the GI tract

Can cause oral thrush in AIDS patients



Malessezia

Normal Eukaryotic flora



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