Yersinia pestis/Plague

The plague is a bacterial infection caused by Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis (Y. pestis), which primarily infects rodents. The disease is transmitted to humans via a fleabite. Inhalation of infectious droplets and handling infected animals or laboratory specimens are other means of transmission. The plague has 3 forms: bubonic (most common form), septicemic, and pneumonic. Bubonic plague results in swollen and tender lymph nodes called buboes in the inguinal area. Pneumonic and septicemic plague can arise as the primary presentation, but also can result from hematogenous spread from the bubonic disease. Diagnosis includes clinical history and findings, culture, polymerase chain reaction (PCR), and serology. The mortality rate is high, so prompt diagnosis and treatment with antibiotics are necessary.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

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General Characteristics

Basic features of Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis

  • Structure: bacilli/rods
  • Gram stain: gram negative 
  • Other stain(s): 
    • Stains such as Wright’s, Giemsa’s, and Wayson’s
    • Bipolar staining (retain staining at the ends of the cells) or “safety pin” appearance 
  • Spore formation: non-spore forming
  • Invasion and replication in relation to the host cell(s): facultative intracellular
  • Oxygen requirement: facultative anaerobes
  • Enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes/biochemical tests:
    • Oxidase negative
    • Lactose negative

Clinically relevant species and diseases

  • Associated species: Enteropathogenic Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis cause yersiniosis Yersiniosis Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis (discussed separately).
  • Associated disease: plague (“Black Death”)
    • Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis (Y. pestis) predominantly cause disease in rodents; humans are usually incidental hosts.
    • Forms:
      • Bubonic plague (most common)
      • Pulmonic plague
      • Septicemic plague

Epidemiology

Worldwide cases of the plague:

  • Majority of cases are from Africa.
  • Countries with the most prevalent cases:
    • Democratic Republic of the Congo
    • Madagascar
    • Peru
World plague map 2009

World map of plague cases reported to the World Health Organization (WHO), 2000–2009

Image: “World Plague Map – 2000 to 2009 – CDC” by the CDC. License: Public domain.

Plague in the United States:

  • Locations:
    • “4 Corners” (the junction point of New Mexico, Arizona, Colorado, and Utah)
    • West: California, southern Oregon, and western Nevada
  • Period with the most cases: May to October (People are outdoors, and rodents are plenty.)

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Pathogenesis

Reservoir and transmission

  • Plague: zoonotic infection
  • Reservoir: rodents, prairie dogs
  • Transmission: 
    • In areas with poor sanitary conditions and infestations of rats, the infection is acquired by a fleabite (the most common route). 
    • Handling of living or dead mammals 
    • Post-mortem examination of an infected body or laboratory handling of a specimen
    • Inhalation of infectious droplets (such as in bioterrorism) can cause pneumonic plague.
  • Vector: Xenopsylla cheopis (the Oriental rat flea, the most efficient flea vector):
    • Y. pestis multiplies in the flea’s midgut after ingestion of a blood meal. 
    • Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis aggregates can block the flea’s intestine.
    • The flea then regurgitates the bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview into the bite wound with each feeding.
    • In some cases, bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview are transmitted right after feeding on an infected host.

Virulence factors

  • Lipopolysaccharide endotoxin: leads to systemic toxicity in bacteremia
  • Type III secretion system: 
    • Injects Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis outer membrane proteins (Yops) into the host cell
    • Yops trigger cytotoxic events and inhibit phagocytosis as well as biochemical pathways.
  • High-pathogenicity island (HPI)
    • Encodes for an iron-scavenging siderophore, yersiniabactin
    • Yersiniabactin provides the bacterium the ability to take iron molecules needed for growth and dissemination.
  • Virulence regulation by temperature and calcium: 
    • Expression of Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis virulence factors is affected by temperature and free calcium. 
    • Physiologically, the mammalian host temperature is different from that of an insect.
    • Likewise, the calcium concentration is different in intracellular fluid than in extracellular fluids. 
    • Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis: able to adjust virulence factors based on the above actions, with the life cycle continuing in the environment or host
  • Y. pestis:
    • pPCP1 (or pPst): plasmid with genes for enzymes with protease, coagulase, and fibrinolytic activity
    • pFra/pMT: encodes Fraction 1 capsular protein (has antiphagocytic function) and phospholipase D (facilitates survival in the flea’s midgut)

Disease process

Bubonic plague:

  • When a flea bites a human and contaminates the wound with regurgitated blood, the bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview are passed into the tissue.
  • Bacteria enter the dermal lymphatic system.
  • Subsequent effects of the infection: 
    • Replication of Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis → lymph node swelling → hemorrhage or necrosis → suppurative lymphadenitis (bubo)
    • Axillary and groin lymph nodes often affected
  • Lymph nodes get overwhelmed and the infection passes to the bloodstream.

Pneumonic plague:

  • Arises from inhalation of highly contagious infected droplets
  • Can result from hematogenous spread of bubonic plague
  • Rapidly progressive pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia with bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview prominent in the air spaces (segmental → lobar → bilateral lung involvement)

Septicemic plague:

  • Bacteria replicate in the bloodstream, spreading to other organs.
  • Travel to the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs produces secondary plague pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia. (Initially, the bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview are more prominent in the interstitium than in the air spaces.) 
  • Infection of the meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges ( meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis) and gastrointestinal tract can occur.
  • Progresses to:
    • Bacterial endotoxic shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock
    • Disseminated intravascular coagulation Disseminated intravascular coagulation Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation ( DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation): clotting cascade, thrombosis with eventual bleeding from depletion of the clotting factors and platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets 
    • Ischemic necrosis from poor perfusion 
    • Death
Transmission of y. Pestis

The transmission of Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis
Direct contact with rodents or flea bites give rise to bubonic plague while airborne transmission (human-to-human), either by coughing or sneezing, gives rise to pneumonic plague.

Image by Lecturio.

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Clinical Presentation

Bubonic plague

  • Symptoms start within 1 week of inoculation:
    • Headache, malaise, myalgia
    • Fever, chills
    • Painful, swollen, and some suppurative lymph nodes (buboes)
    • Inguinal (most frequent) and axillary lymph nodes often affected
  • Without treatment, serious illness follows from hematogenous spread.
Plague buboes

Bubonic plague: swollen inguinal lymph nodes on a person infected with the bubonic plague

Image: “Plague buboes” by the CDC. License: Public domain.

Pneumonic plague

  • In primary plague pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, symptoms start within 2–3 days of exposure.
  • The initial signs are indistinguishable from several other respiratory illnesses: 
    • Fever
    • Headache
    • Weakness
  • After 24 hours, cough, hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis, and shortness of breath follow. 

Septicemic plague

  • The initial presentation in a minority of cases: septic shock Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and Septic Shock without lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy/bubo
  • Risk factors for septicemia (for all Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis spp.):
    • Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
    • Iron overload or hemochromatosis
  • Hemorrhage occurs in other organs, with tissue vasculature occluded by thrombi:
    • Purpuric lesions
    • Hemoptysis/hematemesis 
    • Gangrene in ears, fingers, and toes
  • Difficult to diagnose, especially in a sporadic presentation without bubo

Diagnosis

Diagnostic tools

  • Clinical history and findings:
    • Travel to endemic areas
    • Animal contact
    • Occupational exposure
    • Suggestive symptoms and examination
  • Smear and culture:
    • Specimens:
      • Buboes: needle aspiration of affected lymph node(s)
      • Lungs: sputum, bronchial/tracheal aspirate 
      • Blood
      • Cerebrospinal fluid
    • Bipolar staining (“safety pin” shape) in Wright’s, Giemsa’s, or Wayson’s stains 
    • Fluorescent antibody stains targeting the capsular F1 antigen
    • Specimen cultured in blood agar, MacConkey agar plates, and brain–heart infusion broth
    • Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis-specific culture medium: cefsulodin, irgasan, and novobiocin (CIN) agar
  • Serology: A titer of > 1:16 is suggestive of the plague.
  • Specific polymerase chain reaction (PCR)
Yersinia pestis fluorescent

Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis: under microscopy, dyed with fluorescent stain

Image: “ Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Enterobacteriaceae: Yersinia spp./Yersiniosis pestis fluorescent” by the CDC/Courtesy of Larry Stauffer, Oregon State Public Health Laboratory. License: Public domain.

Additional tests

  • Laboratory tests:
    • Complete blood count: may show leukocytosis with left shift; in some, may have leukopenia; thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia in DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation
    • Metabolic panel: Multi-organ involvement may show renal and hepatic function abnormalities.
    • Elevated fibrin degradation products and prolonged prothrombin times in septicemia
  • Imaging studies: chest X-ray in pneumonic plague
Chest x-ray pneumonic plague

A patient with pneumonic plague
A chest X-ray shows increased pulmonary markings, with thick interlobar pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura in a patient who presented with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, cough, and dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea after exposure to a herding dog.

Image: “PMC4759734_12879_2016_1403_Fig2_HTML” by Li YF, Li DB, Shao HS, Li HJ, Han YD. License: CC BY 4.0.

Management

Treatment

  • High mortality rate with delay of or without treatment
  • Antibiotics: aminoglycosides Aminoglycosides Aminoglycosides are a class of antibiotics including gentamicin, tobramycin, amikacin, neomycin, plazomicin, and streptomycin. The class binds the 30S ribosomal subunit to inhibit bacterial protein synthesis. Unlike other medications with a similar mechanism of action, aminoglycosides are bactericidal. Aminoglycosides (gentamicin)
  • Alternatives:
    • Doxycycline/tetracycline
    • Streptomycin (ototoxic and nephrotoxic; not widely available) 
    • Levofloxacin, moxifloxacin, ciprofloxacin
    • Chloramphenicol Chloramphenicol Chloramphenicol, the only clinically relevant drug in the amphenicol class, is a potent inhibitor of bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing peptide bond formation. Chloramphenicol is a broad-spectrum antibiotic with wide distribution; however, due to its toxicity, its use is limited to severe infections. Chloramphenicol
  • Droplet isolation of the infected patient (until pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia has been ruled out or > 48 hours of treatment)
  • Post-exposure prophylaxis:
    • Exposure to plague: close contact with a patient who has pneumonic plague or direct contact with infected tissue/fluids
    • Give doxycycline or levofloxacin. 
    • For pregnant women or children: Give trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim-sulfamethoxazole.

Prevention

  • Vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination
    • Not available in the United States
    • Used in military personnel deployed in endemic areas
  • Use of proper personal protective equipment in high-risk occupations
  • Sanitation measures and rodent control
  • In outdoor activities: use of insect repellent, insecticide, and protective clothing

Differential Diagnosis

  • Anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax: an infection caused by Bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus anthracis. Cutaneous anthrax presents with small blisters that become ulcers with a black eschar. In inhalational anthrax, chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain and dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea occur. Bloody diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, abdominal pain, and vomiting are noted in gastrointestinal anthrax. History, PCR, and culture help with the diagnosis. Antimicrobial treatment and antitoxin are given for systemic anthrax.
  • Cat scratch disease: an infection caused by Bartonella Bartonella Bartonella is a genus of gram-negative bacteria in the family Bartonellaceae. As a facultative intracellular parasite, Bartonella can infect healthy people as well as act as an opportunistic pathogen. Bartonella species are transmitted by vectors such as ticks, fleas, sandflies, and mosquitoes. B. henselae is the most common of the 3 species known to cause human disease. Bartonella henselae, a gram-negative bacillus. Patients usually present with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, weight loss, and tender lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy after being bitten or scratched by a cat. Symptomatic treatment is recommended, with azithromycin given for severe illness.
  • Tularemia: a rare infection caused by Francisella tularensis acquired by contact with animal tissue, from ticks, or from biting flies. Infection manifests as a papule, followed by fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, headache, and suppurative lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy. Tularemia may have multi-organ involvement. Diagnosis is by the culture of blood and infected tissue. Treatment is with antibiotics.
  • Pneumonia: an infection of the lung parenchyma most commonly caused by bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview (most common: Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pneumoniae) or viruses. Pneumonia is community acquired (CAP) in 80% of the cases. Diagnosis is based on a clinical presentation of fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, cough, dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, rales, and consolidation on chest X-ray. Atypical pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia may present with milder symptoms and less remarkable imaging. 

References

  1. Prentice, M.B. (2018). Plague and other yersinia infections. In Jameson J, et al. (Ed.)  Harrison’s Principles of Internal Medicine, 20th ed. McGraw-Hill.
  2. Stout, J., Sexton, D., & Bloom, A. (2020). Clinical manifestations, diagnosis, and treatment of plague (Yersinia pestis infection). UpToDate. Retrieved Jan 5, 2021, from https://www.uptodate.com/contents/clinical-manifestations-diagnosis-and-treatment-of-plague-yersinia-pestis-infection
  3. Stout, J., Sexton, D., & Bloom, A. (2020). Epidemiology, microbiology and pathogenesis of plague (Yersinia pestis infection). UpToDate. Retrieved Jan 6, 2021, from https://www.uptodate.com/contents/epidemiology-microbiology-and-pathogenesis-of-plague-yersinia-pestis-infection

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