microbiology chapter 23-microbial diseases of the cardiovascular and lymphatic systems

buboes

swollen lymph nodes

septicemia

acute illness due to the presence of pathogens or their toxins in the blood

sepsis

systemic inflammatory response syndrome (SIRS)

lymphangitis

inflamed lymph vessels

severe sepsis

decreased blood pressure and dysfunction of at least one organ

septic shock

sepsis and uncontrollable decreased blood pressure

gram negative sepsis

also called endotoxin shock

endotoxins (LPS) cause a severe drop in blood pressure

antibiotics can worsen the condition by killing bacteria

treatment involved neutralizing the LPS components and inflammatory-causing cytokines

gram positive sepsis

potent exotoxins that cause toxic shock syndrome

hospital acquired infections

hospital acquired infections

enterococcus faecium and entercoccus faecalis

-inhabit the colon

-colonize wounds and the urinary tract

-resistant to many antibiotics

group b streprococci (GBS)

-neonatal sepsis

puerperal sepsis

also called puerperal fever and childbirth fever

caused by streptococcus pyogenes

transmitted to the mother during childbirth

infects the uterus and progresses to an infection of the abdominal cavity (peritonitis)

endocarditis

bacterial infection of the heart

inflammation of the endocardium

endocardium is the inner wall layer of the heart

lines the heart muscles and covers valves

subacute bacterial endocarditis

impairs the function of the heart valves

from oral or tonsil infection

acute bacterial endocarditis

caused by staphylococcus aureus

pericarditis

inflammation of the sac around the heart from streptococci

rheumatic fever

autoimmune complication of S. pyogenes infection

people aged 4-18 follows strep throat infection

inflammation of the heart valves (immune reaction against streptococcal M protein)

subcutaneous nodules at the joints

sydenham's chorea

10% of rheumatic fever develop this

purposeless, involuntary movements

failing of arms and legs

condition disappears after a few months

tularemia

caused by francisella tularensis (gram neg rod)

zoonotic disease

transmitted from rabbits and squirrels

can be transmitted by ticks and insets

creates an ulcer at the site of entry

bacteria reproduce in phagotcyts (enlarges the regional lymph nodes)

mortality usually less than 30%

brucellosis (undulant fever)

elk, bison cows

swine

goats, sheep, camels

transmitted via milk from infected animals or contact with infected animals

presists in the reticuloendothelial system; evades phagocytes

undulant fever (malaise, night sweats, muscle aches) - rising and falling fever

not usually fatal

bacteria that causes anthrax

bacillus anthracis

gram +, endospore forming aerobic rod

anthrax

found in soil

primarily affects grazing animals

spores introduced into the body are taken up by macrophages and germinate (bacteria enter the bloodstream and release toxins)

anthrax treatment and vaccine

treated with ciprofloxacin or doxycycline

vaccination of livestock

anthrax virulence factors

protective antigen: binds the toxins to target cells, permitting their entry

edema toxin: causes local swelling and interferes with phagocytosis

lethal toxin: targets and kills macrophages

amino acid capsule that avoids and immune response

cutaneous anthrax

90% of natural cases

endospores enter through a minor cut

20% mortality rate without treatment

gastrointestinal anthrax

rare

ingestion of undercooked, contaminated food

50% mortality rate

inhalational (pulmonary) anthrax

rare

inhalation of endospores

bacteria enter the blood stream; progresses into septic shock

near 100% mortality rate

ischemia

loss of blood supply to tissue

necrosis

death of tissue

gangrene

death of soft tissue

gas gangrene

caused by clostridium perfringens, a gram + endospore forming anaerobic rod

grows in necrotic tissue

produces toxins that move along muscle bundles

treatment includes the surgical removal or necrotic tissue and or use of an oxygen rich hyperbaric (high pressure) chamber

systemic diseases caused by bites and scratches

1% of ER visits

dogs make up 80% of reported bites; cats about 10% (cat bites have higher infection rates)

domestic animals can harbor pasteurella multocida (gram - rod, causes local swelling and pain. forms of pneumonia and sepsis may develop)

cat scratch disease

caused by bartonella henselae

aerobic, gram -

inhabits cat RBCs; carried in the blood of 50% of cats

multiplies in the digestive system of cat fleas (cat claws contaminated with flea feces scratch human)

forms a papule at the infection site, swollen lymph nodes, and fever)

ordinarily self limiting (duration of a few weeks)

rat bite fever

transmitted via rat bites

streptobacillary rat bite fever

found in north america

fever, chills, muscle pain

mortality rate of 10%

plague (historically known as black death)

caused by yersinia pestis

bacteria blocks the flea's digestive tract

bacteria enter the bloodstream and proliferate in the lymph tissue (cause intense swellings called buboes (swelling of the lymph nodes in the groin and armpit))

bubonic plague

bacterial growth in the blood and lymph

most common form

50-75% mortality rate

septicemic plague

septic shock due to bacteria in the blood

pneumonic plague

blood bacteria goes to the lungs

easily spread by airborne droplets

near 100% mortality rate

relapsing fever

caued by borrelia (spirochete)

transmitted by soft ticks that feed on rodents

high fever, jaundice, rose colored skin spots

successive relapses are less severe

treated with tetracycline

lyme disease

most common tickborne disease in us

field mice are most common reservoir (tick feeds on mice and infects humans)

ticks feed on deer, but are not infect the deer

ticks must attach 2-3 days to transfer bacteria

first phase of lyme disease

bull's eye rash

flu like symptoms

second phase of lyme disease

irregular heartbeat

encephalitis

facial paralysis

memory loss

third phase of lyme disease

arthritis due to an immune response

typhus

infect the endothelial cells of the vascular system

block and rupture the small blood vessels

spread by arthropod vectors

typhus fever

carried by the body louse

transmitted when louse feces are rubbed into the bite wound from the louse

prolonged fever and a rash of red spots due to subcutaneous hemorrhaging

treated with tetracycline and cholrampheniocol

endemic murine typhus

transmitted by the rat flea

rodents are common hosts

mortality rate less than 5%

cliniclaly indistinguishable from typhus fever

treated with tetracycline and chloramphenicol

rocky mountain spotted fever

spread by wood ticks and dog ticks

measles like rash, except that the rash also appears on the palms and soles

without early diagnosis, mortality rate is approximately 20%

treatment with tetracycline and cholramphenicol

burkitt's lymphoma

tumor of the jaw

most common childhoos cancer in africa

malaria suppresses the immune system and is tied to burkitt's lymphoma

infectious mononucleosis (mono)

caused by epstein- barr virus

childhood infections are often asymptomatic

transmitted via saliva; incubation of 4-6 weeks

fever, sore throat, swollen lymph nodes, enlarged spleen

replicates in resting memory b cells

yellow fever

injected into the skin from mosquito

fever, chills, headache, nausea, vomiting

jaundice due to liver damage

endemic in tropical areas

no treatment, however there is an attenuated vaccine available

ebola hemorrhagic fever

spread by contact with infected body fluids

damages blood vessel walls and interferes with coagulation (blood leaks into surrounding tissue)

internal and external bleeding

mortality rate of 90%

chagas' disease

protozoan disease

caused by flagellated protozoan

reservoir in rodents, opossums, and armadillos

vector: kissing bug

chronic form of the disease causes megaesophagus and megacolon (death due to heart damage)

therapy is difficult due to trypannosome multiplying intracellularly

toxoplasmosis

caused by tocoplasma gondii (undergoes its sexual phase in cat intestines)

oocysts shed in shed in cat feces

contact with cat feces or undercooked meat introduces oocysts to the intestines

oocysts form trophozoites that invade cells; may become a chronic infection

primary danger is congenital infection (stillbirth, neurological damage)

malaria

caused by parasites

transmitted by mosquitos

4 major forms

plasmodium vivax

mildest and most prevalent form of malaria

dormant in the liver

plasmodium ovale and plasmodium malariae

form of malaria

benign

restricted geographically

plasmodium falciparum

most deadly form of malaria

severe anemia

blocks capillaries

affects the kidneys, liver, and brain

cycle of malaria

mosquito bite transmits sporozoite into the blood stream (enters the liver cells resulting in the release of merozoites into the blood stream)

merozoites infect RBCs and again undergo schizogony (ruptures the infected RBCs, releasing toxic compounds. causes chills and fever)

some merozoites develop into gametocytes and are taken up by a mosquito, repeating the cycle

malaria

difficult to develop a vaccine (the bacteria rapidly mutates and evades an immune response)

difficult to diagnose without sophisticated equipment

treatment : artemisinin

prevention: bed nets