MIC 141: EXAM 4 DoD (Pseudomonas, Lyme Disease, Relapsing Fever, & Whooping Cough)

What type of bacterium is Pseudomonas aeruginosa?

A Gram negative rod.

What is a notable characteristic of Pseudomonas aeruginosa's motility?

It has a single polar flagellum and uses polar type IV pili to move across solid surfaces.

What is the typical habitat of Pseudomonas aeruginosa?

It is free-living in soil, seawater, and freshwater.

What percentage of people are intestinal residents of Pseudomonas aeruginosa?

Approximately 10%.

What are some common infections caused by Pseudomonas aeruginosa?

Pneumonia, urinary tract infections (UTIs), surgical wound infections, septicemia, and burn wound infections.

What is the significance of biofilms in Pseudomonas aeruginosa infections?

Biofilms account for up to 60% of human infections, providing adherence, interfering with immune access, and increasing resistance to antibiotics.

What are some virulence factors of Pseudomonas aeruginosa?

Phospholipases, proteases, amylase, pectinase, cellulase, exotoxins, slime layer, biofilm formation, adhesins, and LPS.

How does Pseudomonas aeruginosa control its virulence factors?

Through quorum sensing.

What is a common environmental reservoir for Pseudomonas aeruginosa infections?

Sponges and washcloths.

What is a notable symptom of Pseudomonas aeruginosa infections?

Grape-like odor and blue pus.

What are effective antibiotics against Pseudomonas aeruginosa?

Fluoroquinolones, gentamicin, and imipenem.

What is the mortality rate for ventilator-assisted pneumonia caused by Pseudomonas aeruginosa?

38%.

What is the mortality rate for burn wounds infected with Pseudomonas aeruginosa?

60%.

What is the mortality rate for AIDs patients infected with Pseudomonas aeruginosa?

50%.

What is the mortality rate for cystic fibrosis patients infected with Pseudomonas aeruginosa?

50%.

What is a unique feature of the pigments produced by Pseudomonas aeruginosa?

They can be green, brown, red, and/or yellow water-soluble pigments.

What is the significance of the large genome of Pseudomonas aeruginosa?

It has a genome size of 6.3 megabases, contributing to its adaptability and virulence.

What type of pathogen is Pseudomonas aeruginosa classified as?

An opportunistic pathogen, primarily affecting immunocompromised hosts.

What is the impact of multi-drug resistant Pseudomonas aeruginosa?

It caused 32,600 hospital-acquired infections and 2,700 deaths in 2017.

Lyme disease

Most common vector-borne disease in the US and Europe

Borrelia burgdorferi characteristics

Strictly host-associated spirochete; diderm without LPS; limited ~1.3 Mb genome; no iron requirement

Borrelia metabolism

Obligate extracellular pathogen; aerotolerant anaerobe; ATP generated via glycolysis and lactate fermentation

Borrelia enzootic cycle

Cycle between ticks, small mammals, and humans

Lyme disease epidemiology

Estimated 476,000 cases per year in the United States

Lyme disease US distribution

Found in upper Midwest, Northeast, and expanding regions

Lyme disease diagnosis

Diagnosed based on symptoms, exposure history, and serologic testing (antibodies)

Lyme disease testing issues

False positives and false negatives common; no approved molecular tests (PCR)

Why no PCR for Lyme

Bacteria do not stay in bloodstream long enough for reliable detection

Borrelia species in Ixodes ticks

Ticks may carry up to three Borrelia species, complicating testing

Lyme disease treatment

Most patients treated successfully with antibiotics

Post-treatment Lyme disease syndrome

Persistent Lyme-like symptoms after treatment; occurs in ~20% of patients

PTLDS cause

Unclear; current evidence suggests no persistent infection

PTLDS additional antibiotics

Not recommended; controversial topic

Lyme disease prevention

No human vaccine; prevent Lyme by preventing tick bites

Why dogs have Lyme vaccines

Dogs develop more severe disease and are frequently exposed; easier to immunize population

Relapsing fever

Caused by multiple Borrelia species in different vectors

Relapsing fever groups

Soft tick relapsing fever (STRF), hard tick relapsing fever (HTRF), louse-borne relapsing fever (LBRF)

Soft tick family

Argasidae

Relapsing fever enzootic cycle

Transmitted between rodents and soft ticks

Relapsing fever symptoms

Fever, headache, muscle aches, chills

Severe symptoms during fever episodes

Shaking, drenching sweats, low blood pressure

Other relapsing fever symptoms

Dizziness, joint pain, nausea, vomiting, appetite loss

Rare relapsing fever symptoms

Facial paralysis, eye pain/redness, vision changes

Relapsing fever mechanism

Antigenic variation helps Borrelia evade antibodies

Relapsing fever epidemiology

251 cases from 11 of 12 states (2012-2021), 55% hospitalized, no deaths

Relapsing fever geography

Distribution stable since 1990s

Relapsing fever diagnosis

Based on symptoms and laboratory tests

Blood smear test

Detects Borrelia in Giemsa-stained blood film; best early in illness

Serologic test for relapsing fever

Detects antibodies; best if sample collected ≥14 days after symptom onset

PCR for relapsing fever

Molecular detection useful during asymptomatic periods or soon after treatment

LBRF treatment

Single oral dose: tetracycline 500 mg, doxycycline 200 mg, or erythromycin 500 mg (if tetracyclines contraindicated)

TBRF treatment

Requires longer 7-10 day antibiotic therapy due to relapse risk ≥20%

Relapsing fever IV treatment

Used when oral therapy not tolerated; includes doxycycline, erythromycin, tetracycline, or procaine penicillin G

STRF prevention

Remove rodent nests and eliminate soft ticks; avoid sleeping in rodent-infested structures

Signs of rodent activity

Droppings, shredded nesting material, chewing marks, stale odor

Soft tick prevention indoors

Keep beds away from walls; avoid sheets touching floor; avoid sleeping on floor

Rodent exclusion

Seal homes; keep chipmunks and squirrels out

Professional pest control

Removes nests, treats cracks/crevices with pesticide, establishes prevention plan

STRF outdoor precautions

Avoid caves/rodent burrows; wear long sleeves/pants

Tick bite prevention

Use EPA-registered repellents or clothing treated with 0.5% permethrin

Whooping cough definition

Acute, highly contagious bacterial disease affecting the respiratory system

Pertussis etiologic agent

Bordetella pertussis

Bordetella pertussis characteristics

Gram-negative coccobacillus; obligate aerobe; fastidious organism

History of pertussis

Outbreaks described since 16th century; B. pertussis discovered by Jules Bordet in 1906; epidemics occur every 3-5 years

Pertussis incubation period

7-10 days before symptoms begin

Catarrhal stage symptoms

Cold-like symptoms including runny nose, mild cough, low fever

Paroxysmal stage symptoms

Severe coughing attacks, "whooping" sound, vomiting after coughing

Convalescent stage

Symptoms gradually decrease; slow recovery phase

Broken blood vessels

Forceful coughing may cause subconjunctival hemorrhages or facial petechiae

Pertussis complications

25% pneumonia; 4% seizures; 1% permanent brain damage; 1% fatality rate

Pertussis reservoir

Humans only; no animal or insect reservoirs

Pertussis transmission

Respiratory droplets; coughing and sneezing

Who is most affected

Children under 1 year and senior adults experience the most severe disease

Vaccinated adolescents/adults

Can contract pertussis with milder symptoms due to waning immunity

Who can get pertussis

Anyone unvaccinated, improperly vaccinated, or inadequately protected by vaccine

Pertussis treatment

Rest, proper nutrition, antibiotics (erythromycin is drug of choice)

Why symptoms linger

Pertussis toxin causes prolonged symptoms even after bacteria are cleared

Macrolide resistance

Emerging cases of resistance against macrolide antibiotics

Case isolation

Patients should be isolated to prevent transmission

Pertussis prevention

Immunization is the primary preventive measure

Pertussis vaccine history

Commercial vaccine available in mid-1930s; widely used by mid-1940s

DTaP vaccine

Pediatric formulation for diphtheria, tetanus, and acellular pertussis

Tdap vaccine

Adolescent and adult booster formulation

Pre-vaccine pertussis cases

~200,000 cases per year in the United States before vaccines

Post-vaccine pertussis cases

Average 2,900 cases per year (1980-1990)

Pertussis trends

Cases have been increasing since the 1990s

Kennel cough

Bordetella bronchiseptica infection in dogs; related organism but not same disease as human pertussis