Chapter 23 Flashcards
Gram-Negative Sepsis
Klebsiella spp., E. coli, and Pseudomonas aeruginosa are most frequently involved
– Elizabethkingia spp. are an emerging pathogen in this problem area
• Antibiotics can worsen the condition by killing bacteria.
• Treatment involves neutralizing the LPS components and
inflammatory-causing cytokines
Gram-Positive Sepsis
Hospital-acquired infections
– Enterococcus faecium and Enterococcus faecalis
▪ Inhabit the colon
▪ Colonize wounds and the urinary tract ▪ Resistant to many antibiotics
Group B streptococci (GBS)
Streptococcus agalactiae
– Neonatal sepsis
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Streptococcus pyogenes
Puerperal Sepsis
Staphylococcus aureus
• Acute bacterial endocarditis
Subacute bacterial endocarcletits
Alpha-hemolytic streptococci
Acute bacterial endscarditits
Staphylococcus aureus
Pericardotits
Streptococci
Rheumatic Fever
Autoimmune complication of S. pyogenes infections • Inflammation of the heart valves
– Immune reaction against streptococcal M protein
• Subcutaneous nodules at the joints
Sydenham’s chorea
Invoularty purposeless movements
Complication of rheumatic fever
Brucellosis (Undulant Fever)
Brucella spp.
– Aerobic gram-negative coccobacilli
– Brucella abortus (elk, bison, cows)
– Brucella suis (swine)
– Brucella melitensis (goats, sheep, camels)
• Transmitted via milk from infected animals or contact with infected animals
• Perisists in the reticuloendothelial system; evades phagocytes
• Undulant fever (malaise, night sweats, muscle aches) – Not usually fatal
Anthrax
Bacillus anthracis +, endospore
Gangrene
Clostridium perfringens, a gram-positive,
endospore-forming anaerobic rod
Systemic Diseases Caused by Bites and Scratches
,
Causes 1% of visits to emergency rooms in hospitals Dogs make up 80% of reported bites; cats about 10%.
– Cat bites have higher infection rates. • Pasteurella multocida
– Gram-negative rod; causes sepsis
• Staphylococcus, Streptococcus, Corynebacterium
Plague
Caused by Yersinia pestis
– Gram-negative rod
– Transmitted by the rat flea
– Endemic to rats, ground squirrels, and prairie dogs
• Bacteria blocks the flea’s digestive tract.
– Flea bites the host and ingested blood is regurgitated
into the host.
• Bacteria enter the bloodstream and proliferate in the lymph tissue.
– Cause intense swellings called buboes
rat flea
Plague
Relapsing Fever
Caused by Borrelia spp. – 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
Lyme barreliosis
By borrelia burgdorferi
Typhus
Rickettsia spp.
– Obligate intracellular parasites
– Infect the endothelial cells of the vascular system
▪ Block and rupture the small blood vessels – Spread by arthropod vectors
Typhus fever
epidemic louseborne typhus)
– Caused by Rickettsia prowazekii
Rocky Mountain spotted fever (
tickborne typhus)
– Caused by Rickettsia rickettsii
– Spread by wood ticks and dog ticks
– Measles-like rash, except that the rash also appears on the palms and soles
Burkitt’s Lymphoma
Tumor of the jaw; most common childhood cancer in Africa
– Due to Epstein-Barr virus
Infectious Mononucleosis
Infectious Mononucleosis
Cytomegalovirus Infections
Cytomegalovirus
• Remains latent in white blood cells
• Infected cells swell
– Form “owl’s eyes” inclusions
• May be asymptomatic or mild in adults
• Cytomegalic inclusion disease (CID)
– Transmitted across the placenta; causes mental retardation or hearing loss in newborns
• Transmitted sexually, via blood, saliva, or by transplanted tissue
Marburg virus
green monkey virus
Ebola Virus Disease (EVD)
Caused by the Ebolavirus, a filovirus similar to the
Marburg virus
– Reservoir is the cave-dwelling fruit bat near the Ebola River in Africa.
– Spread by contact with infected body fluids
Hantavirus pulmonary syndrome
Caused by the Sin Nombre virus
Chagas Disease
American Trypanosomiasis)
• Caused by Trypanosoma cruzi
– Flagellated protozoan
– Reservoir in rodents, opossums, and armadillos
• Vector is the bug
– Defecates trypanosomes into the bite wound of humans
• Chronic form of the disease causes megaesophagus and megacolon.
– Death due to heart damage
• Therapy is difficult due to trypanosome multiplying intracellularly.
Toxoplasmosis
Toxoplasma gondii
Malaria
Plasmodium parasites
• Transmitted by mosquitoes
Plasmodium vivax:
mildest and most prevalent form; dormant in the liver
Plasmodium ovale and Plasmodium malariae:
benign; restricted geographically
Plasmodium falciparum:
most deadly; severe anemia; blocks capillaries; affects the kidneys, liver, and brain
Malaria prevention and treatment
No vaccine and difficult to diagnose
Leishmaniasis
Transmitted via female sandflies
– Promastigote transmitted in saliva from bites – Amastigote proliferates in phagocytic cells
Leishmania donovani (
visceral leishmaniasis) – Invades the internal organs
Leishmania tropica
cutaneous leishmaniasis)
– Forms a papule that ulcerates and leaves a scar
Leishmania braziliensis
mucocutaneous leishmaniasis) – Affects the mucous membranes
Schistosomiasis
The Helminthic Disease of the Cardiovascular and Lymphatic Systems
Caused by small flukes called Schistosoma
– Feces carrying eggs get into the water supply
▪ Snails serve as the intermediate host.
– Cercariae released from the snail penetrate the skin of
humans
– Eggs shed by adult schistosomes in the host lodge in
tissues, forming granulomas.
Schistosoma haematobium:
urinary schistosomiasis
Schistosoma japonicum:
intestinal inflammation; found in Asia
Schistosoma mansoni:
intestinal inflammation; found in South America
