Exam 2 Lecture 15 Flashcards
True or false: Mycoplasma and Ureaplasma spp are relatively easy to grow/culture
False: they are fastidious
M. pneumoniae primarily causes what type of infections?
Middle/lower respiratory tract infections
Which Mycoplasma species cause GU infections?
M. hominis & M. genitalium
True or false: M. hominis & M. genitalium are primarily GU organisms, but they can disseminate to the lungs.
True
Ureaplasma are similar to M. hominis and M. genitalium in that they typically cause:
GU infections
Describe Mycoplasma ultrastructure
not a typical appearance for a bacterial cell wall: 3 layers, no peptidoglycan (no cell wall)
Since Mollicutes do not have a cell wall, what does this imply about Tx?
we can’t use cell wall antibiotics (vancomycin, beta lactams) because they don’t have peptidoglycan
Size/shape of M. pneumoniae
Tapered rods, 1-2 x 0.2 microns (tiny)
Size/shape of M. hominis
Coccoid, 0.2-0.3 microns (smaller than M. pneumoniae)
Size/shape of Ureaplasma spp
Coccoid, 0.2-0.3 microns (same as M. hominis)
What does a small genome imply for the Mollicutes?
less flexibility for LOF mutations since they have lost their own metabolism pathway genes; depend on host cell for growth/replication
When Mollicutes are grown on medium, what do we see?
Colonies aren’t immediately visible, very small, fried-egg appearance
How long does it take to grow M. pneumoniae in lab?
several weeks
How long does it take to grow M. hominis & Ureaplasma in lab?
2-4 days
True or false: culture is the best/primary method to detect Mollicutes
false: takes a long time + risk of false negatives
M. pneumoniae typically causes diseases such as?
bronchitis (tracheobronchitis); pneumonia (CAP)
What is the age group that is most at risk for M. pneumoniae infections?
5-17 y.o. (school age kids + adolescents)
There are typically _____ cases/year of pneumonia caused by M. pneumoniae
~ 100,000
True or false: M. pneumoniae infections are becoming increasingly nosocomial acquired
False: more community acquired
____ infections can occur with M. pneumoniae
Recurrent
What are some extrapulmonary infections of M. pneumoniae?
encephalitis, dermatitis, SJS
Encephalitis is typically ____-acquired and occurs in __. Symptoms include:
hospital; kids; acute psychiatric symptoms, rarely stroke
If extrapulmonary, M. pneumoniae commonly causes ____ and ____ ____
SJS (dermatidites); cold agglutinin
What is SJS?
Stevens-Johnson Syndrome; auto-immune mediated necrolisis of skin involving mucous membranes + epidermis
M. pneumoniae adhesin is called __ ____, and is important for ____ ____
P1 adhesin; glidiing motility
M. pneumoniae produces ___ ___, which is another bipartite toxin
CARDS toxin
Other Mycoplasma and Ureaplasma diseases include: (lots)
- upper urinary tract infections
- non-gonococcal urethritis
- cervicitis, salpingitis, endometritis, PID
- post-partum fever
- congenital/neonatal infections
- septic arthritis
- bacteremia
- meningitis, osteomyelitis, wound infx
Ureaplasma virulence factors
- IgA protease
- Urease
- multiple adhesins (poorly characterized)
- MB (major antigen from host perspective)
Lab detection (2)
- we rely on molecular methods since Cx is tough *
1. PCR (good but not great, 40% sensitivity in early infx)
2. Serology for M. pneumoniae (4-fold change in titer is significant)
Mycoplasma and Ureaplasma Treatment
- emperic antibiotics for outpatient PNA
- usually azithromycin, levo/moxifloxacin, oral tetracycline
Is there a vaccine available for Mycoplasma/Ureaplasma?
no
True or false: for M. hominis infection, usually we use doxycycline to prevent abx increased resistance
true
Legionella characteristics
- fastidious
- bacillus
- gram-negative but poor staining
L. pneumophila is transmitted via ___
water supply (environmental transmission)
L. pneumophila life cycle
- often lives in amoeba bc it’s a facultative parasite
2. multi-organism biofilm growth in water supplies
How does L. pneumophila cause disease in humans?
transmitted through aerosolized water, inhalation, then invades phagocytes
Legionella are ___ to grow than Mollicutes, but needs ____-____ agar.
easier; charcoal-containing
Describe L. pneumophila gram stain
gram negative, filamentous bacilli (but coccobacillary in humans)
what do L. pneumophila colonies look like when cultured
grey-white, round/convex
Legionella are ____ ____, ____, and ____.
obligate aerobes; fastidious; asacharolytic (in vitro)
Asacharolytic
do not derive energy from sugars, instead they catabolize amino acids
All Legionella spp require ____
L-cysteine
____ is important for Legionella pathogenesis
iron acquisition system or siderophore
For Legionella cultivation, use ___ ___ ___ ___
Buffered Charcoal Yeast Extract (BCYEalpha)
What environmental conditions are best for Legionella growth
- 35-37ºC
- pH 6.7-6.9 (generally lower pH)
- also salt sensitive
Legionella Lab detection
- Urine antigen testing for L. pneumophila serogroup 1 ONLY (!!)
- PCR 16S rDNA (helpful for dif serogroup)
- report to public health labs
Legionnaire’s Disease usually caused by ___ ___
serogroup 1
Legionnaire’s Disease characterizations
- bacterial pneumonia acquired from aerosolized water
- 18k cases/year in US
- systemic symptoms like headache, muscle ache, loss of appetite, fever
Legionnaire’s Disease treatment
erythromycin, tetracycline, other drugs higher CFR
Besides Legionnaire’s Disease , L. pneumophila can also cause ___ ___
pontiac fever
Legionnaire’s Disease is ___ attack rate, ___ mortality
low, high
Pontiac fever characterizations
- upper respiratory infection, not pneumonia
- high attack rate, non fatal
- symptoms within 4-60 hrs exposure
- cough, fever, loss of appetite, aches, belly pain, increased HR
- more so inflammatory response than actual infection
