Blood and Lymphatic Infections

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Blood and Lymphatic Infections
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Blood and lymphatic systems
Figure 28.1
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Lymphangitis
Figure 28.2
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Bacterial blood vascular system

• Subacute bacterial endocarditis
• Gram negative septicemia

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Subacute bacterial endocarditis

• Caused by Staphylococcus epidermidis ( a few
  others)
• (usually localized to one of valves on the left
  side of the heart
• Marked fatigue and slight fever over a few weeks
  or months, may abruptly develop a stroke
• Bacteria gain access to blood during dental
  procedures, toothbrushing or trauma and induce
  biofilm formation on a deformed valve
• Attach to abnormal tissue

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Features of subacute bacterial endocarditis
Table 28.1
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Gram negative septicemia

• 30 of cases of septicemia
• Ex. Escherichia coli, Pseudomonas aeruginosa,
  Bacteroides sp.
• Nosocomial illness
• Symptoms include violent shaking chills and
  fever, anxiety, and rapid breathing
• Originates from an infection elsewhere in body

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• Endotoxins lead to shock and death because
  macrophages respond defensively (TNF, IL-1
  release)
• Complement is activated by endotoxin
• Clotting cascade is activated by endotoxin
  (disseminated intravascular coagulation DIC).

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Endotoxin - septicemia
Figure 28.3
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Bacterial lymph nodes and spleen

• Tularemia
• Brucellosis
• Plague

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Rabbit fever (Tularemia)

• Caused by Francisella tularensis, gram - rod
• Often called Rabbit fever
• Widespread among wild animals. Risk to wildlife
  handlers. Most US cases contracted while
  skinning animals vaccine available to those at
  risk.
• Exposure to animal blood or via insects and ticks
• A steep-walled skin ulcer spread to lymph.
• Lymph nodes are large and tender, fill with pus,
  and drain spontaeously. Can grow in macrophages
• Pneumonia occurs in 10-15 of cases with 30
  mortality rate.

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Ulceroglandular - tularemia
Figure 28.4
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Cases of Tularemia
Figure 28.5
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Features of tularemia
Table 28.2
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Brucellosis

• Caused by Brucella melitensis , gram - rod
• 150 US cases/year (about 20 times more go
  unreported)
• Often called undulant fever, Bangs disease
• Gradual onset with mild fever, sweating, aches,
  enlarged lymph nodes, weight loss.
• Fever occurs over weeks or months.
• Organism penetrates mucous membranes,
  disseminated to heart, kidney.

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• Grow in phagocytes (resist killing by antibody
  and antibiotics)
• Mortality due to endocarditis
• Brucellosis is a chronic infection of domestic
  animals
• 60 of human cases occur in meat-packers
• Also found in unpasteurized milk
• Osteomyelitis is most frequent serious
  complication

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Features of brucellosis
Table 28.3
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Plague

• Caused by Yersinia pestis, gram pleiomorphic
• Often called Black death (killed a quarter of
  Europes population 1346-1350
• Symptoms develop 1-6 weeks after flea bite
  large, tender lymph nodes (buboes) in the region
  that drains from area of flea bite
• High fever, shock, delirium, patchy bleeding
  under skin, cough and bloody sputum (if lungs
  involved, pneumonic plague)

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• Multiple virulence factors
• Pla protease causes blood clots to dissove by
  activating plasminogen activator, also destroy
  complement proteins
• Yops proteins interfere with phagocytosis that
  would initiate inflammation
• F1 part of antiphagocytic capsule
• Ex. Bubonic plague transmitted by fleas
  (organisms blocks digestive tract of fleas (makes
  them very hungry)

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• Taken up by macrophages of lymph nodes.
  Inflammation doesnt occur for several days.
• Pneumonic plague occurs in 10-20 of cases
  (especially dangerous and communicable)
• Dark hemorrhages in skin are from DIC
• Mortality rate for untreated plague is 50-80
• Plague is endemic in rodent populations
• Can remain viable in dried sputum for weeks
• Treament by gentamycin or tetracylin is effective
  if given early

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Yersinia pestis
Figure 28.6
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Virulence factors
Table 28.4
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Infected fleas
Figure 28.7
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Features of plague
Table 28.5