Microbiology An Introduction, Chapter 23: Microbial Diseases of the Cardiovascular and Lymphatic Systems - PDF

Microbiology an Introduction Thirteenth Edition, Global Edition Chapter 23 Microbial Diseases of the Cardiovascular and Lymphatic S...

Microbiology an Introduction Thirteenth Edition, Global Edition Chapter 23 Microbial Diseases of the Cardiovascular and Lymphatic Systems Copyright © 2021 Pearson Education Ltd. All Rights Reserved Bacterial Diseases of the Cardiovascular and Lymphatic Systems Sepsis and Septic Shock 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.3 Lymphangitis, One Sign of Sepsis Copyright © 2021 Pearson Education Ltd. All Rights Reserved Gram-Negative Sepsis Also called endotoxin shock Endotoxins (lipopolysaccharides [LPS]) cause a severe drop in blood pressure 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Gram-Positive Sepsis Potent exotoxins that cause toxic shock syndrome 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Bacterial Infections of the Heart Endocarditis – Inflammation of the endocardium Subacute bacterial endocarditis – Impairs the function of the heart valves – Alpha-hemolytic streptococci from an oral or tonsil infection Acute bacterial endocarditis – For example caused by Staphylococcus aureus Pericarditis – Inflammation of the sac around the heart – Caused for example by Streptococci Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.4 Bacterial Endocarditis Fibrin-platelet vegetations Normal appearance Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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 – Purposeless, involuntary movements Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.5 A Nodule Caused by Rheumatic Fever Nodule Elbow joint Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Anthrax (1 of 3) Caused by Bacillus anthracis – Gram-positive, endospore-forming aerobic rod 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 Treated with ciprofloxacin or doxycycline Vaccination of livestock Copyright © 2021 Pearson Education Ltd. All Rights Reserved Anthrax (2 of 3) Bacteria produce 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 an immune response Copyright © 2021 Pearson Education Ltd. All Rights Reserved Anthrax (3 of 3) Cutaneous anthrax – Endospores enter through a minor cut. – 20% mortality rate without treatment Gastrointestinal anthrax – Ingestion of undercooked, contaminated food – >50% mortality rate Inhalational (pulmonary) anthrax – Inhalation of endospores – Bacteria enter the bloodstream; progresses into septic shock – Near 100% mortality rate Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.7 Anthrax Lesion Copyright © 2021 Pearson Education Ltd. All Rights Reserved Gangrene Ischemia: loss of blood supply to tissue Necrosis: death of tissue Gangrene: death of soft tissue Gas gangrene – Caused by Clostridium perfringens, a gram-positive, endospore-forming anaerobic rod  Grows in necrotic tissue  Produces toxins that move along muscle bundles – Treatment includes the surgical removal of necrotic tissue and/or use of a hyperbaric chamber Soft tissue refers to tissues that connect, support, or surround other structures and organs of the body. Soft tissue includes muscles, tendons, ligaments, fascia, nerves, fibrous tissues, fat, blood vessels, and synovial membranes. Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.8 The Toes of a Patient with Gangrene Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Plague (1 of 2) 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Plague (2 of 2) 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 – Bacteria in the lungs – Easily spread by airborne droplets – Near 100% mortality rate Antibiotic prophylaxis for exposure Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.10 A Case of Bubonic Plague This photograph shows the characteristic black fingers caused by hemorrhaging under the skin. Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Lyme Disease (Lyme Borreliosis) (1 of 2) Caused by Borrelia burgdorferi Most common tickborne disease in the United States Field mice are the most common reservoir – Nymphal stage (not adult) of the tick feeds on mice and infects humans Ticks feed on deer, but are not infected. Ticks must attach two to three days to transfer bacteria. Copyright © 2021 Pearson Education Ltd. All Rights Reserved Lyme Disease (Lyme Borreliosis) (2 of 2) First phase – Bull’s-eye rash; flulike symptoms Second phase – Irregular heartbeat; encephalitis; facial paralysis; memory loss Third phase – Arthritis due to an immune response Diagnosis via ELISA, indirect fluorescent-antibody (FA) test, or Western blot Treated with antibiotics – More difficult to treat in later stages Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.14 The Common Bull's-Eye Rash of Lyme Disease Copyright © 2021 Pearson Education Ltd. All Rights Reserved Typhus (1 of 4) Caused by Rickettsia spp. – Obligate intracellular parasites – Infect the endothelial cells of the vascular system  Block and rupture the small blood vessels – Spread by arthropod vectors Copyright © 2021 Pearson Education Ltd. All Rights Reserved Typhus (2 of 4) Typhus fever (epidemic louseborne typhus) – Caused by Rickettsia prowazekii – 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 antibiotics (e.g. tetracycline and chloramphenicol) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Typhus (4 of 4) 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 – Without early diagnosis, mortality rate is approximately 20% – Treatment with antibiotics (e.g. tetracycline and chloramphenicol) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.17 The Rash Characteristic of Rocky Mountain Spotted Fever Copyright © 2021 Pearson Education Ltd. All Rights Reserved Viral Diseases of the Cardiovascular and Lymphatic Systems Burkitt’s Lymphoma Tumor of the jaw; most common childhood cancer in Africa – Due to Epstein-Barr virus Malaria suppresses the immune system response to the virus Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.18 A Child with Burkitt’s Lymphoma Copyright © 2021 Pearson Education Ltd. All Rights Reserved Infectious Mononucleosis Caused by Epstein-Barr virus Childhood infections are often asymptomatic Transmitted via saliva; incubation of 4 to 7 weeks Fever, sore throat, swollen lymph nodes, enlarged spleen Replicates in resting memory B cells – Form unusual lobed nuclei – Produce heterophile antibodies  Weak and multispecific Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.20 A. Large Lymphocyte with the Unusual Lobed Nucleus That is Characteristic of Mononucleosis B. Normal Lymphocyte a b Copyright © 2021 Pearson Education Ltd. All Rights Reserved 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Emerging Viral Hemorrhagic Fevers (1 of 3) Marburg virus (green monkey virus) – Transmitted from African monkeys – Headache, high fever, vomiting blood, profuse bleeding internally and externally Copyright © 2021 Pearson Education Ltd. All Rights Reserved Emerging Viral Hemorrhagic Fevers (2 of 3) 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 – Damages blood vessel walls and interferes with coagulation  Blood leaks into surrounding tissue – Mortality rate of 90%; however, recombinant vaccine in Phase 3 testing in 2016 showed 100% protection Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.21 Ebolavirus Copyright © 2021 Pearson Education Ltd. All Rights Reserved Emerging Viral Hemorrhagic Fevers (3 of 3) Hantavirus pulmonary syndrome – Caused by the Sin Nombre virus – Fatal pulmonary infection; lungs fill with fluids – Found in the western United States – Hantavirus causes Hemorrhagic fever with renal syndrome  Found in Asia and Europe  Affects kidney function Copyright © 2021 Pearson Education Ltd. All Rights Reserved Protozoan Diseases of the Cardiovascular and Lymphatic Systems 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. Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.22 Trypanosoma cruzi, the Cause of Chagas Disease (American Trypanosomiasis) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Toxoplasmosis Caused by Toxoplasma gondii – Undergoes its sexual phase in cat intestines  Oocysts 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Malaria (1 of 3) Caused by Plasmodium parasites Transmitted by mosquitoes Affects 300 million globally; 500,000 deaths annually Four species: – 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 – Life cycle is previously described Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Figure 23.25 Malaria RBCs Merozoites RBCs Ring forms Merozoites being Malarial blood smear; released from lysed RBCs note the ring forms. Copyright © 2021 Pearson Education Ltd. All Rights Reserved Malaria (3 of 3) Difficult to develop a vaccine – Plasmodium rapidly mutates and evades an immune response. Difficult to diagnose without sophisticated equipment Prophylaxis – Chloroquine; Malarone for chloroquine-resistant areas Treatment – Artemisinin Prevention – Bed nets Copyright © 2021 Pearson Education Ltd. All Rights Reserved Leishmaniasis Transmitted via female sandflies – Promastigote transmitted in saliva from bites – Amastigote proliferates in phagocytic cells Promastigote Amastigote Leishmania donovani (visceral leishmaniasis) – Invades the internal organs Leishmania tropica (cutaneous leishmaniasis) – Forms a papule that ulcerates and leaves a scar Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.26 Cutaneous Leishmaniasis Leishmania braziliensis (mucocutaneous leishmaniasis) – Affects the mucous membranes Copyright © 2021 Pearson Education Ltd. All Rights Reserved Helminthic Disease of the Cardiovascular and Lymphatic Systems Schistosomiasis 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 Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.27 Schistosomiasis Adult female flukes lay eggs. Female Definitive host (size: 15–20 mm) Cercariae Adult travel through flukes circulatory system Eggs to intestinal blood vessels, where they Male mature into adults. Eggs reach Cercaria body of Free-swimming (0.13 mm) water after cercariae penetrate being excreted human skin, in human losing tail. feces or urine. Cercaria Egg (0.33 mm) (0.15 mm) Eggs hatch into free- swimming Intermediate larvae (miracidia). host Cercariae are released from the snail. Miracidium reproduces Miracidium in snail, forming Miracidium (0.2 mm) several cercariae. penetrates snail. Life cycle of Schistosoma, cause of schistosomiasis Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 23.28 A Granuloma from a Patient with Schistosomes Egg Granuloma Copyright © 2021 Pearson Education Ltd. All Rights Reserved