MICRO EXAM 2 PART 2

Learning Objectives

• Chlamydia and Chlamydiophila are obligate intracellular parasites
• They do not have peptidoglycan
• Borrelia is a Gram-negative spirochete
• Diseases, transmission, prevention, and treatment should be described for Chlamydia trachomatis and Borrelia bergdorferi
• The concept of zoonoses should be defined, alongside 10 examples

Chlamydia and Chlamydiophila

• Cause eye and lung infections STD's
• Are obligate intracellular parasites
• Differ from Rickettsia by not being closely related
• Do not have normal peptidoglycan
• Cause very different diseases
• Present in textbooks together

Chlamydia trachomatis

• Can make proteins and DNA
• Cannot make ATP and gets it from human cells
• Does not contain normal peptidoglycan, but has a cell wall
• The cell wall is sensitive to beta-lactams
• Common cause of urethritis sexually transmitted in the US
• Can result in neonatal conjunctivitis and infant pneumonia
• Causes trachoma, and possibly blindness
• Loses less sugar molecules, making the organism a gram -ve rod

Chlamydia trachomatis Urethritis

• 2 million new cases per year in the US
• Causes infection of the urethra in both males and females
• Leads to pain and a small discharge
• Females are often asymptomatic but can still transmit the disease
• Prevented by practicing safe sex and having trustworthy sex partners
• Treated with one dose of azithromycin (1 g oral)
• Can be treated with 7 days of tetracycline, erythromycin, or a fluoroquinolone

Trachoma

• Caused in part by C. trachomatis "serovar trachoma" (trachoma strain)
• Many people in the Middle East and North Africa are infected
• About 2 million people are now blind due to this infection
• Requires a chronic disease to cause blindness
• Typically infected as a child
• Develops scars on the eyes slowly
• Causes progressive eye damage
• Transmitted by droplets, hands, nose, clothing, towels, and flies

Trachoma Symptoms/Infection

• Conjunctivitis happens first and leads to small scars on the conjunctiva
• The scars then scratch the surface of the eye causing eye damage and scars
• Damage to the conjunctiva leads to the turning in of eyelashes
• Turning of eyelashes causes damage to the eye each time one blinks
• Scarring of the cornea leads to blindness
• Develops more in dusty, sandy areas
• Transmitted by droplets, hands, nose, clothing, towels, flies

Trachoma Prevention and Treatment

• Reduce transmission by frequent face and hand washing
• Requires clean towels and clothing
• Needs treatment of carriers and reduction in the number of flies
• Treat with antibiotics early, before damage to the eye occurs
• Effective antibiotics include azithromycin, tetracyclines, and fluoroquinolones

Zoonoses

• "Both wild and domestic animals are living reservoirs of microorganisms that can cause human diseases
• Diseases that occur primarily in animals and can be transmitted to humans called zoonoses"
• Humans are accidental hosts to zoonoses
• Examples include Influenza, West Nile Virus, Rabies, Ebola, Bubonic plague, Anthrax, Salmonellosis, Rocky Mountain Spotted Fever, Typhus, Malaria, and Toxoplasmosis

Lyme Disease

• Is a zoonosis
• The Infectious agent is _Borrelia bergdorferi
• Borrelia is a Gram-negative spirochete
• Similar to a spirillum shape, but has more tight turns
• Reservoir hosts are mice and deer

Lyme Disease Transmission

• Transmitted by the Ixodes tick bite
• Found in US, Northeast, Upper Midwest, Pacific West and definitely in Teas
• Cases are 15,000 reported per year in Us

Lyme Disease Symptoms

• Symptoms vary, and a diagnosis is often missed or difficult
• In 3-30 days after bite, the bite site develops erythema migrans, a flat red border and central clearing, with or without bull's eye, 5 to 50 cm diameter
• There is malaise, severe fatigue, fever, chills, body ache for several weeks in first phase

Neurological Complications

• Varying degrees of permanent joint or nervous system damage may develop in individuals with late-stage Lyme disease
• The long-term effects may be controversial in some ways
• It is hard to prove the association of the sometimes vague symptoms with a disease years earlier

Lyme Disease Prevention

• Avoid ticks using insect repellents
• Wear long pants and socks
• Make frequent body checks
• Reduce tick numbers in your yard with the correct insecticide in areas with many ticks
• Prevent more serious late symptoms by early treatment

Lyme Disease treatment

• Includes: amoxycillin, tetracycline, or cephalosporins

Obligate Intracellular Bacteria

• Requires the host cell to grow/reproduce
• Includes Chlamydia and Rickettsia species

Rickettsia, Ehrlichia, and Coxiella

• Species are very small Gram-negative rods and intracellular parasites
• Rickettsia includes rickettsii, prowazekii, and typhi
• Cannot grow on petri plate, but they grow in some mammalian and arthropod cells
• Rickettsiac and Ehrlichia die quickly outside the host cell
• Coxiella can survive desiccated for months to years outside of host cells
• Make protein on their own and make ATP via the TCA cycle but use cellular ATP when available
• Infections and diseases include, spotted fevers, typhus, ehrlichiosis, and Q fever

Rocky Mountain Spotted Fever (RMSF)

• Most common Rickettsia disease in US
• Caused by Rickettsia rickettsii
• Vector and Reservoirs Include: Dog Tick and Wood Tick
• Ticks must remain attached for >6 hours to infect a person
• Causes leakage of blood vessels, hypovolemia, & organ failure
• The death rate is as high as 20% if left untreated

Rocky Mountain Spotted Fever Symptoms

• About 10 days after infection there may be;
• A fever and chills
• Headaches with Muscle pain
• A rash usually develops on extremities and spreads to the trunk
• The rash may appear later
• Good diagnostic skills help suggest the disease
• History and symptoms are important

Rocky Mountain Spotted Fever diagnosis & treatment

• "Best" test: Indirect Fluorescent Antibody (IFA) method
• IFA finds antibodies in patient's blood that are specific against Rickettsia antigens
• Takes 2-3 weeks to develop antibodies
• Antibodies may not be present at the first clinic visit so testing is useful for confirmation
• Treated with tetracyclines and fluoroquinolones

RMSF Diagnosis & Treatment Problems

• The symptoms are nonspecific and common with other diseases
• The rash may not appear during the clinic visit, but may appear later
• May not ask or mention tick exposure to the doctor
• A pharmacist can play a valuable role in noting how the patient is doing
• Should note if they develop a rash, and if they are not doing well, meaning the wrong antibiotic given. A doctor, pharmacist and patient must communicate

RMSF Prevention

• There's no commercial vaccine
• Avoid ticks by use clothing and apply repellent; Examine body and remove ticks when found

Host, Reservoirs and Vectors

• Host is the organism supporting growth of a pathogen-human in RMSF
• Reservoir is the organism/environment normally allowing growth of pathogen-deer/dog
• Vector aids in transmission of pathogen from the reservoir to the host. Tick in Tick borne RMSF

Typhus

• Causes headaches, joint pain, fever, cough
• Has epidemic and endemic forms
• Epidemic: The vector responsible is lice and humans are the reservoir in (Rickettsia prowazekii)
• The vector for Endemic typhus include mouse and rat fleas (Rickettsia typhi) and rodents, opossums and cats
• aka Murine Typhus
• Murine Typhus has 100 cases per year, mostly in S. Texas and S. California
• Prevented by avoiding lice and fleas and treated with tretracyclines
• Epidemic typhus is very uncommon in US and mainly found in other countries war torn countries
• Head and rat louse are carriers

Human Erlichiosis

• Caused by Ehrlichia and the Vector responsible is Tick
• The target and reservoir for this bacteria are in Phagocytes of Rodents, Deers, Dogs
• Show Similar RMSF symptoms such as: but rash frequently not present
• It can be determined to check and analyze blood work for phagocyte information
• Treatment :Tetracyclines and Prevention is Avoiding Ticks

Human Erlichiosis Mortality Rate & Diagnostics

• Under 5% in elderly or AIDS patients
• Clincal exam history and DNA is taken for antibody testing

Q Fever

• Is caused by Coxiella burnetii, it is gram-negative and an an obligate intracellular parasite
• Q Fever spreads not by ticks but through humans generally by inhalation of particles
• From the birth of cats, dogs, goats, sheep (in placenta and fluid)
• Outside of a cell, Extra cellular Coxiella can survive for extended time like animal hides/soils or dust
• Most people get 20-30 acute cases per year which cause mild symptoms
• Chronic cases may cause the subacute endocarditis form
• This usually forms at aritficial surfaces as well ad damaged heart valves
• Diagnostic methods will include a clinical history and testing tests/Treatment : Tetracyclines/Prevention : vaccine, but rarely used avoiding animals avoiding milk products