Clinical Micro exam 4

Bordatella pertussis

Causes whooping cough, endemic with resurgence every few years

What are the stages of whooping cough

Catarrhal stage: most contagious, runny nose, etc

Paroxysmal: bouts of sever coughing, not as contagious

What is the prevention for pertussis?

DTaP vaccine but does not provide lifelong immunity

What is the incubation period of pertussis?

3-21 days

What are the whooping cough ressurgences due to?

waned immunity, new strains, lessened vaccine potentcy

What toxin is present in B.pertussis?

pertussis toxin that paralyzes the smooth muscle in the airway causing the whooping

RSV

enveloped RNA virus

RSV transmission

droplets, indirect contact with fomites

What is the main virulence factor for RSV

syncytial formation (multinucleate cells) of the respiratory tract cells

Primary TB symptoms

tubercule formation that causes lesions in the lung, tuberculin reaction

Secondary TB

When TB rests in macrophages then reactivates, causes “consumption’ where there is weight loss, etc

Mycobacterium tuberculosis

An acid faest bacterium with myolic acids in its cell walls that makes it slow growing

TB transmission

respiratory droplets, can survive 8 months in aerosol particles

Mantoux test

IGRA test for TB on a blood test

Treatment of TB

multidrug regiment for up to 1 year

MDRTB

TB that is resistant to at least isoniazid and rifampin

pneumonia

characterized by anatomical diagnosis that is an inflamitory condition of the lungs

S. pneumoniae

main cause of comminity acquired pneumonia. G+ coccus

legionella pneumophila

motile G- organism that can live inside amoeba

Legionella transmission

aerosols from water sources

Pontiac fever

a less serious manifestation of legionella

Legionarres disease diagnosis

x-ray and antigen tests

Causes for atypical pneumonia

Mycoplasma, Chlamydophila

Mycoplasma

Causes walking pneumonia

Mycoplasma virulence factor

Ciliostasis stops clearing of the airway, extracellular pathogen, acts as a superantigen

Hantavirus

Community acquired pneumonia, causes lung edema, enveloped virus

hantavirus transmission

rodent droppings (urine, saliva, feces) that contaminate dust

Histoplasma capsulatum

Community acquired pneumonia that comes from soils and bird droppings

Pneumocysis jiroveci

fungus that causes pneumonia in AIDS patients

Healthcare aquired pneumonia

MRSA, G- bacteria

defenses of the GI tract

IgA, bile, salive, peristalsis, mucus layer

GALT

lymphoid tissue in the gut that has T and B cells, IgA, and house commensal organisms

Function of the gut biota

digestions, vitamin K (e.coli), teaching the immune system

Enterobius vermicularus

pinworms that have a sticky coating on the eggs, eggs hatch in the small intestine and larvae mate in L.I

What life cycle does E. vermicularis use?

A; fecal oral

What are the halmark signs and test for pinworms?

pronounced itching, scotch tape test

Trichuris trichura (whipworm)

Found in areas with poor sanitation, can cause rectal prolapse and bleeding due to worms burrowing through the mucosa

Whipworm life cycle

type A; fecal oral

D. latum

Largest tapeworm known, intermediate host is fish, definitive is humans

What type of lifecycle does D. latum use?

Type C; contaminated meat

Where does D. latum develop?

in the intestine

T. solium

pork tapeworm that uses type C transmission, worms are able to mugrate through the body (and brain)

T. solium life cycle

Pigs have cysticerci- infective stage in the muscles, humans ingest and scolex attaches. Humans can be definitive or intermediate

T. solium treatment

Praziquantel

Schistosomiasis

Invade intact skin and borrow until small/large intestine or bladder (haemotobium) is reached

Schistosomiasis life cycle

Snail is the intermediate host, release carcariae into the water and they burrow into humans

What type of worm is schistosoma?

Trematode/fluke

Schistosomiasis pathogensis

Cloaking with hosts immune protein

How are gram negative enteric bacteria classified?

H: Flagellar antigen

K: capusle antigen

O: cell wall antigen

Salmonella

found in poutrly, eggs, G- H2S producing motile

What species of Salmonella causes disease?

Enterica, tehre are over 2500 serotypes

enteric fever

Salmonella gets engulfed by macrophages, replicate in the blood, cause immune response in the host

Characteristics of salmonella

Motile, can live in inhospitable environments, acid labile, high infectious dose

salmonellosis symptoms

fever, diarrhea, bloody stool

Salmonella treatment

avoid contact with the bacterium and trimethoprim-sulfomethoxazole

Shigella

non motile G- non endospore forming, non H2S or urease producing. Cannot survive outside the host

shigellosis symptoms

Dystentery, fever, mucus

Shigella pathogensis

Invades villi of the large intestine, invades mucosa through peyers patches, then causes tissue distruction

shiga tocxin

causes serious damage to intestine and systemic affects

Shigella transmission

Person to person in crowded areas

If a patient is suspected of having shigellosis, what should be done?

confirmation diagnosis and start on trimethoprim/ sulfamethoxazole

STEC (shiga toxin producing e.coli)

E. coli O:157 H:7, can cause HUS and neurological symptoms

How does STEC acquire shiga tocin?

Transduction event from a phage

STEC transmission

Contaminated food or undercooked beef

If a patient is suspected of STEC, what should be done?

Stool culture and Shiga toxin test

Best way to prevent STEC infections?

Food hygiene; shiga toxin is heat labile and E. coli, antibiotics are not recommended