Tics And Things Flashcards
Mycoplasma pneumoniae
Type of infection; Size; Shape; Colony; Growth
- Upper respiratory infection
- bronchitis
- pneumonia
- Smallest free-living organism (size and genome)
- Many Shapes: LACK rigid cell wall
- NO PEPTIDOGLYCAN
- Unusual colony morphology on agar plates
- Fastidious
- Very slow growing
Mycoplasma Cell Wall
Lacks rigid cell wall: NO PEPTIDOGLYCAN
- instead 3 layered cell membrane
- COMPLETELY RESISTANT TO PENICILLIN and other antibiotics that attack cell wall
- Generally stains poorly or not at all
Mycoplasma: Major Antigenic Determinants
Membrane glycolipids and proteins (because lack cell wall!)
- antibodies to mycoplasma CROSS REACT WITH RBCs
Mycoplasma Fastidious: needs…
Cholesterol/sterol
Mycoplasma pneumoniae and atypical (walking) pneumonia
General Information
- Transmitted person-person via coughing (respiratory secretions)
- Prominent in closed populations
- Laboratory confirmation rarely obtained
Mycoplasma pneumonia Virulence Factor
HIGH AFFINITY for RESPIRATORY EPITHELIAL CELLS
- attaches to cilia and leads to loss of function
- critical for virulence
Clinical Characteristics of Atypical pneumonia
Mycoplasma pneumonia
SLOW ONSET AND COUGH
- Incubation period 2-3 weeks (very long)
- Typically a GRADUAL ONSET of fever, malaise, headache, COUGH
Mycoplasma pneumonia High Risk Factor
Sickle-cell disease: leased to agglutinins and digital necrosis
M. Pneumonia Laboratory Diagnosis
- Currently problematic because so slow
- Often treat without diagnosis, which doesn’t help because could be treating for general instead of walking
- PCR-based tests most specific and rapid
Spirochete
- Don’t like to grow on cultures
- Coiled cell wall, motile, endoflagella, Gram -
Endoflagella
Found on Spirochetes; acts as cork screw to cell walls
How best to visualize Spirochete
Dark-field microscopy or immunofluorescent stains
- culturing very difficult
Spirochetes that cause Disease
BLT
Borrelia - Lyme disease - Relapsing fever Leptospirosis - Leptospirosis Treponema - Syphilis
Manifestations in stages if left untreated!
Borrelia burgdorferi vs Borrelia recurrentis
Burgdorferi: Lyme
Recurrentis: relapsing fever
Lyme Disease
Occurs in stages
- Early: rash; disseminates
- Later: heart; joins; skin; CNS
Borrelia burgdorferi (Transmission; Timing of Exposures)
LYME disease
- transmitted by small deer tick: IXODES
- most exposures from May-July: NYMPHAL STAGE: tics very aggressive
MOST COMMON VECTOR BORNE ILLNESS IN THE US AND EUROPE
Ixodes
Tic that causes Lyme
- problematic because vector for many other pathogens so often confection; need to treat both (i.e. Lyme and babesiosis)!
B. burgdorferi Virulence Factor
Surface exposed lipoproteins (OspA-F)
Bburg:OspA-f
Clinical Characteristics of B. Burgdorferi
Lyme Disease
Multi-stage infection
- Early Infection Stage 1: localized infection
-slowly expanding ERYTHEMIA MIGRANS 7-10 days after tic bite
- Early Infection Stage 2: disseminated infection
- flu-like symptoms; skin lesions
- months later: pain in joints, bones, bursar, muscles and tendons
- Bell’s paisy
- Late Infection Stage 3: persistent infection (months-years after tick bite)
- chronic nervous system and joint involvement
Lyme Disease Most Common Clinical Manifestations
EM (Erythema Migrans)>Arthritis>Bells paisy
Lyme Disease Laboratory Diagnosis
Not perfect; suggests two-test serological approach
- deals with antigen antibody binding assay
Often simply assumed in presence of EM
Borrelia Recurrentis
Relapsing Fever
- epidemic (no longer seen): body lice
- ENDEMIC: transmitted from soft body tick (diff than those from LYME)
- rodents and small animals are reservoir
- western US
Clinical Characteristics of Relapsing Fever
- sudden onset of fever with chills
- lasts 3-6 days and ends abruptly
- starts again 7-10 days later
Leptospirosis
Primarily a disease of wild and domestic animals (dogs!)
- humans get infected through direct/indirect contact
- indirect contact most common: ingestion of contaminated food or water, mucosal membranes
- rapidly disseminates into blood stream
VIABLE FRESH WATER ONLY
- wide variation fo disease; multisystem disease with high mortality
