Systemic infections

Bacterial, Tick-Borne Diseases examples

✓ Lyme Disease

✓ Babesiosis

✓ Rocky Mountain Spotted Fever

viral diseases

✓Infectious mononucleosis
✓ Arboviruses – mosquito
vector
✓ Filoviruses- direct contact
with infected fluids

protozoan infections

malaria

lymph

Plasma that has diffused out of capillaries into
and around tissues

lymph is normally

sterile

WBC in lymph do what

fight foregn pathogens

lymph delivers contaminating microbes to lymph nodes to be

phagocytosed

Blood is normally

axenic (sterile)*

(but recent studies say no and blood microbiome dwells inside blood cells)

venipuncture

different ubes with different anticoagulants for specific tests

anticoagulant of choice

sodium polyanethol sulfonate (SPS- yellow top)

what is done when a microbial infection in blood is suspected

blood culture

Septicemia:

presence of microbial infection on the blood that

causes disease

Bacteremia:

septicemia caused by bacteria

Viremia:

presence of viruses in blood

• Remember that aseptic meningitis refers to viral

Fungemia:

presence of fungi in blood

• Parasitemia:

presence of parasites in blood

toxemia

presence of toxins in the blood

Septic shock:

extremely low blood pressure (hypotension) as a result of inflammation and dilation of blood vessels.High mortality rate

Bacteremia can spread to

joints and bones causing osteomyelitis and to CNS causing meningitis

Lymphangitis:

septicemia spreads to the lymphatic vessels, appearing as a red streak

bacteremia clinical presentation

High fever (over 38°C 99°F)

• Chills, nausea, vomiting, diarrhea,

shortness of breath, and malaise

Bacteremia – Causative Agents

all bacteria can cause bacteremia as long as they can access the bloodstream and survive to multiply

Most septicemia causing bacteria are

opportunistic pathogens

ex Escherichia coli, Pseudomonas aeruginosa, Bacteroides,

Staphylococcus, and Streptococcus

bactericemia caustive agents virulence factors

• Capsule: useful to prevent phagocytosis from WBC circulating in

bloodstream

• Siderophores: certain bacteria require iron for metabolism; therefore

they use molecules that chelate (“trap”) iron from carrier proteins in plasma

• Hemolysins: substances that destroy RBCs

bactericemia pathogenesis

Septicemia usually presents as a result of

• direct inoculation of bacteria into blood ex

• • Medical procedures

• • Catheters, surgery, central venous

• line, dialysis

• • IV-drug users

• • Abrasions

• • Result of a secondary infection

who is at higher risk for bactericemia

people with AIDS, cancer, diabetes, malnutrition,

elderly, newborns are all more susceptible

which gram class usually causes severe septicemia

G-

in bacteremia, outer meembrane of dying bacteria releases

Lipid A. causes stronger immune response

exotoxins

produced by gram-positive bacteria only

• Cytotoxins: cell lysing

endotoxins

produced by gram negatvie bacteria

• Lipid A portion of LPS from outer cell membrane

toxic shock syndrome caused by

Staphylococcus aureus and Streptococcus pyogenes

toxic shcok syndrome caused by bacteria secreting

exotoxin: toxic shock syndrome toxin (TSST), a type of superantigen

toxic shock syndrome symtoms

exaggerated immune response

resulting in high fever, vomiting, rash,

and extremely low blood pressure

Staphylococcal Toxic Shock Syndrome

• can grow in vagina or wounds

• associated with superabsorbent tampons

Bacteremia and Toxemia prevention

taking care of wounds, promptly treat initial

infections, sterilization of surgical equipment

Bacterial Endocarditis

Bacteria infect the endocardium

triggering inflammation,

endocarditis and the formation of

vegetations (masses of platelets

and clotting factors in the

endocardium that bury the bacteria)

Bacterial endocarditis symtpoms

similar to bacteremia signs as well as tachycardia and heart murmurs. complications can lead to strokes are cardiac failure

most common cause of bacterial endocarditis

Viridans alpha streptococci

other things that can bacterial endocarditis

Pseudomonas aeruginosa,

Neisseria meningitidis, Escherichia coli, Salmonella spp.,

Staphylococcus spp., Streptococcus spp.

who is at highest rsik for bacterial endocarditis

Patients with tooth lesions or wounds, IV-drug users, artificial

heart valve recipients

Borrelia burgorferi – Lyme disease phases

1. bulls eye rash

2. neurological symptoms

3. severe arthritis

lyme disease signs and stages

1. Erythema migrans
2. Early disseminated stage
• Multiple erythemas
• Arthritis
• Musculoskeletal pain
• Meningitis
• Lymphocytoma
• Carditis
3. Late disseminated stage
• Acodermatitis
• Arthritis
• Neurological symptoms
4. Post-treatment Lyme disease
syndrome

Babesia spp caused by

B. microti (a parasite! not a bacterium). spread throgh ticks

Babesiosis signs

General malaise, fever,

headaches, chills, sweating,

fatigue, and weakness

(nonsynchronous)

• Hemolytic anemia

• Renal failure

• Hepatosplenomegaly

Rocky Mountain Spotted Fever (RMSF) caused by

Rickettsia rickettsii (spread by ticks)

Rocky Mountain Spotted Fever (RMSF)

Headache, vomiting, and muscle pain

• Rash consisting of small, flat, pink/red, non-

itchy spots that spread from the wrists,

arms, and ankles inward to the torso

rocky mountain spotted fever pathophysiology

infects endothelial cells

rocky mountain spotted fever complications

If untreated, may cause blood vessel damage impacting circulation to the arms and legs
• May require limb amputation
• Vessel damage in 5% of cases causes fatal organ or brain
bleeding
• Untreated cases can be fatal within 8 days

viral diseases of cardiovascular system

• Infectious mononucleosis (EBV)
• Arboviruses
• Yellow fever
• Dengue
• Filoviruses
• Ebola
• Marburg

Infectious Mononucleosis causitive agent

epstein barr virus

Infectious Mononucleosis transmission

person-to-person or sharing of fomites (glasses) or via inhalation of respiratory droplets containing the virus
• “Kissing disease”

infectious mononucleosis pathogenesis

infects epithelial cells of throat and salivary glands, enters the blood where it infects B lymphocytes. becomes latent. infects and replicates in oropharyngeal epithelium, tonsils and salvary glands.

infectious mononucleosis signs

Lymphadenitis (especially lymph nodes of the neck)

• Extreme fatigue, nausea, loss of

appetite, headache, and sore throat

• May lead to chronic tiredness

many hosts of mononuelcosis are

asymptomatic

Arboviruses 2 types

yellow fever and degnue fever

yellow fever symotoms

Acute: headache, fever, and muscle pain 3-5 days
• Severe disease (15%): high fever, severe nausea, violent-black
vomit. Liver damage, internal bleeding, delirium, coma, and death

arborvirus pathogenesis

Viruses infect and replicate in the liver and spleen, leading to
viremia
• Cytokine release incites systemic inflammatory response
• Causes leaky capillaries, decreased blood pressure, may lead to
shock and organ failure

yellow fever transmission

Jungle: Transmits primarily between monkeys via mosquitoes in jungle areas
• Intermediate: In areas with both villages and jungle, mosquitoes infect both humans and monkeys
• Urban: Human-to-human transmission via mosquitoes

dengue fever is common or uncommon

Most common arboviral disease in humans. can be asymptomaitc

dengue fever 1st stage

febrile phase - Fever, vomiting, rash, and
body aches

dengue fever 2nd stage

critical stage
• Extreme abdominal pain, persistent vomiting, and dehydration
• Hemorrhagic features may develop
• Bleeding from the nose or mouth, petechiae, and leaky capillaries
• May lead to decrease in blood volume, shock, organ failure, and death
• For both – Monkeys/humans are initially infected and then pass the virus via mosquito vector

arborviruses transmission

Monkeys/humans are initially infected and then pass the virus via
mosquito vector

filoviruses examples

Marburg and Ebola viruses

filoviruses transmission

Transmission is person-to-person,
Ebola – ingestion of bush meat,
Marburg – inhalation of bat droppings

how does filovirus replicate

Virus replicate in monocytes,
macrophages, and dendritic cells

filoviruses can cause

• severe hemmoragic fever

• Extensive tissue necrosis of liver, spleen, lymph nodes, and lungs

• Hemorrhage causes edema and hypovolemic shock

malaria caused by

protozoan

species of plasmodium that cause malaria

P. falciparum (*most deadly)
• P. vivax (*most prevalent)
• P. malariae
• P. ovale
• <P.knowlesi – emerging parasite>

definitive host of malaria is

where sexual reproduction takes place

malaria signs

Causes cycles of fevers, headaches, delirium, body aches (due to rupture of RBCs & release of toxins)

• Death from loss of RBCs, complications from blood clots

plasmodium depends on what to complete its life cycle

Anopheles mosquito and humans