Mycoplasma and Streptococcus Flashcards
what are the 5 types of Mycoplasma? describe each : where are they found, oxygen req etc
1 Mycoplasma- parasites of animal mucous membranes
- >60 species
2 Ureaplasma- (T strain mycoplasmas).
-Microaerophilic.
-Req cholesterol and urea to grow
-Associated with nongonococcal urethritis
3 Acholeplasma- widely an animal parasite
-Can grow w/out sterols
- common contaminants of cell lines in tissue culture
4 Anaeroplasma
- strictly anaerobic
- inhabit bovine/ovine rumen
5 Spiroplasma
-helical, motile
-parasites of arthropods and plants (citrus stubborn disease and corn stunt disease)
- few cause disease in animals
describe the structure of Mycoplasma/Mollicutes
- lack cell wall (only memb) O sensitive to osmotic lysis
- plasma memb strengthened by STEROLS
- pleomorphic
- very small (smallest living cells)
- low GC content
- contaminate tissue cultures
- can be grown in lab media
what is the appearance of Mycoplasma on solid agar media?
fried egg shape
describe genome of Mycoplasma
SMALLEST GENOME of any self replicating organism- encodes 472 genes
which Mycoplasmas are human pathogens? How are they diagnosed? What do they cause? How are they treated?
1) M. pneumonia- causes resp tract inf—> results in PRIMARY ATYPICAL PNEUMONIA (walking pneumonia- milder)
Diagnosis- patchy diffuse X-ray, serological tests, culture
Treatment- ABs that don’t target cell wall (Erythromycin , doxycycline, azithromycin)
2) GENITAL MYCOPLASMAS- M.genitalium, M.hominis, Ureaplasma urealyticum. Causes non-gonococcal (non-chlamydial) urethritis (NGU).
Men-infertility
Women- cercitis, endometriosis, tubal factor infertility
Diagnosis- PCR- it is difficult to culture
Treatment- doxycycline/erythromycin or azithromycin
3) M.penetrans- infects UROGENITAL and RESP tracts
Pathogenesis- penetrates into human cells, intracellular replication and persistence for months/years.
Associated w/ HIV
describe lactic acid bacteria
- how do they obtain energy
- growing media/cond
- prod lactic acid as a prod of fermentation
- non spore forming
- non motile
- lack cytochromes, use sub level phosphorylation NOT ETC
- obtain energy from sugars
- req many vitamins, aa and purines and pyrimidines
- aerotolerant (growth not affected by air)
- grown on media cont yeast , peptone, supplemented by fermentable carbohydrate. colonies are small, barely pigmented
- ACID TOLERANT- many cannot grow at pH 6 . SELECTIVE VALUE-eliminate competition
what is the shape of streptococci?
chains (divides in one plane)
what is the shape of lacobacillus?
rods
what is the shape of pediococcus?
pairs or tetrads
what is the shape of leuconostoc?
spheres in chains
what is the meaning of homofermentative? give an example
only prod LACTIC ACID as the product of fermentation
eg Strep, Enterococcus
what is the meaning of heterofermentative? give an example
produces LACTIC ACID and other products, such as CO2 and ETHANOL
eg Leuconostoc
describe Streptococci
shape
media for growth
catalase?
- spherical cells
- chains
- req complex media (blood agar)
- unable to make haem group for cytochromes or catalase
how can haemolysis be used to group streptococci
if COMPLETE haemolysis (clear zone)—> BETA haemolytic
if PARTIAL haemolysis (greenish-brown zone) —> ALPHA haemolytic
if NO haemolysis —> GAMMA haemolytic
how can antigen/serologic methods be used to group streptococci
use LANCEFIELD GROUPS OF BETA-HAEMOLYTIC STREPS:
- heat up the Streps to 150°C
- identify the carbohydrate antigen attached to it
what are Group A Streptococci?
S.pyogenes
Group B Streptococci
who doe sit affect?
S. agalactia
cattle and humans
what does Group A Strep caused by? what does it cause?
where is it found?
how can you test for Group A Strep?
caused by S.pyogenes
- antigenicity of M-PROTEINS in cell wall—> grouping
- main Streptococcus diseases in humans
Found: 5-30% of people are healthy carriers in throat and nasopharynx
Test: Bacitracin sensitivity test—> zone of inhibition
where are Group D Streptococci found?
intestinal tract of man and animals
hence name ENTEROCOCCI
what does Group A Strep cause?
- strep throat (treat w/ ABs)
(inflammaton of uvula, tonsils have white exudate) - impetigo skin infection
(mostly young children, small vesicles on skin form a thin amber crust) - Scarlet fever
Symptoms: fever, susceptibility to ENDOTOXIC shock, ERYTHEMATOUS rash
(caused by S.pyogenes strain carrying a bacteriophage (virus that infects bacteria) that produces either A,B or C TOXIN.
-Cellulitis (inf of deep layers of skin) - Necrotizing fasciitis (invasive, toxigenic, infection of soft tissues and fascia)
Non supporative
- Rheumatic fever 2/3 weeks after untreated pharyngeal Joints and heart affected Maybe immunological reaction -Glomerulonephritis After initial Strep infection Strep directed antibody reacts with glomerular basement membrane/ antibody-antigen complexes deposited onto basement membrane. Results in loss of protein via kidneys---> kidney failure
where is group B Strep found?
who do group B Strep infections affect the most &what do they cause?
how is it diagnosed?
-vaginal flora of 25% of women
- affects NEWBORNS- pneumonia, septicaemia, meningitis
Diagnosis: hippurate test (hydrolyse sodium hippurate forming purple colour)
where is group D Strep found?
what do they cause?
why is it of high concern?
- found in fecal flora
- cause UTI and wound infections
- high concern due to V high VANCOMYCIN resistance
(could it pass resistance to other bac??)
what is the major group within the alpha haemolytic Strep?
what can they cause?
the Viridans (not a species, but a GROUP)
S.Viridans
Can cause BACTERIAL ENDOCARDITIS-inf of HEART VALVE—> fatal if not treated
where does the Viridans group inhabit?
throat and nasopharynx
give an example of a member of the Viridans. what does it cause
S.mutans
causes dental CARIES/CAVITIES
what is the shape of Strep. pneumoniae?
outer structure?
habitat?
- lancet shaped, arranged in pairs
- ENCAPSULATED- can resist phagocytosis
- habitat=normal commensal of upper resp tract
what can Strep. pneumoniae cause?
what are mortality rates like?
- acute lung inflammation
-chills, fever and pleural pain - alveoli fill with exudate
- may cause BACTEREMIA (25%)
- pneumococci may invade other tissues (sinuses, middle ear and meninges)
MORTALITY- 10-20% (1M deaths p/a)
2nd most common cause of meningitis in adults
how is Strep. pneumoniae diagnosed?
- sputum smears examined for G+ve bacteria that are encapsulated
- Quellung test: specific antibody for bacteria w/ bacteria. Causes capsule to swell O more visible & refractile due to antibody attachment
- Optochin (AB) disks- disk diffusion assay, zone of inhibition suggests Strep.pneumoniae
- Bile solubility test
how is Strep. pneumoniae treated?
why are there concerns about treatment?
penicillin G (except meningitis- treated with chloramphenicol) concerns due to HIGH AB resistance O treated w/ Vancomycin, but resistance could spread from enterococci.
how is Strep. pneumoniae prevented?
VACCINE- cont polysaccharide from 23 most prevalent types
who is Strep. pneumoniae vaccine given to?
high risk groups (chronic resp disease)
all children in UK
is mycoplasma a low or high GC content bacteria?
low (firmicute)
is mycoplasma a lactic acid producing bacteria?
yes
is Strep a low or high GC content bacteria?
low (firmicute)
is Strep a lactic acid producing bacteria?
yes
how does M.pneumoniae cause disease?
- settles and binds on respiratory epi cell
- using P1 adhesion proteins, adherence accessory proteins and interactive proteins
- results in: colonisation of mucous memb and eukaryotic cell surfaces
how does M.pneumoniae cause cell disruption?
produces hydrogen peroxide
what vector is used by Spiroplasma?
leafhopper
