bacteria basics Flashcards
acute phase cytokines
IL-1
IL-6
TNFα
hair-like structures that mediate adherence of bacteria to surfaces (respiratory, GI tract)
fimbriae
forms attachment between 2 bacteria during conjugation
pilus
pilus allows transfer of DNA (plasmids = resistance, virulence factors = toxins) from one bacteria to another
conjugation
longer than fimbriae and pilus
provide whip-like motility
flagella
gelatinous polysaccharide coat of bacteria
adds in attachment to foreign material (indwelling catheter, teeth)
glycocalyx
if organized glycocalyx (polysaccharide coat) and firmly adherant to bacteria (sugar coat)
capsule
if loosely adherant and less organized glcyocalyx (polysaccharide coat)
produced by bacteria
shields from antibiotics, hard to remove
slime/biofilm
protects bacteria from phagocytosis
allows for time to evade immune system and divide
capsule (type of virulence factor)
test to detect encapsulated bacteria:
anti-capsular serum added to bacteria
positive: capsule swells under microscope
quellung reaction
encapuslated bacteria
SHiN **Streptococcus pneumoniae **Haemophilus influenza type B **Neisseria meningitidis
most vulnerable population to encapsulated bacteria infection
splenectomy patient vaccinate against polysaccharide capsule (antigen): **Streptococcus pneumoniae **Haemophilus influenza type B **Neisseria meningitidis
yeast with capsule
cryptococcus neoformans
ribosomes
location of protein synthesis
2 subunits combine to translate mRNA
prokaryote (bacterial) ribosomes
70S (50S + 30S)
eukaryote (human) ribosomes
80S (60S + 40S)
genetic material separate from chromosomal DNA and
replicate separately
genes for: antibiotic resistance, enzymes, toxin production
transferred during conjugation
plasmids
mechanisms of genetic change in bacteria
conjugation via pili and plasmids
transformation
transposition
transduction
DNA released from lysed cell and then taken up by a living bacterium
DNA fragments incorporated into chromosomal DNA→recombinant bacteria
transformation
what bacteria can acquire genetic material via transformation
SHiN **Streptococcus pneumoniae **Haemophilus influenza type B **Neisseria meningitidis
small segments of DNA that can self-exise and relocate
transfer from chromosome to plasmid (allow for AR, spread to another bacteria via conjugation) and vice versa, chromosome to chromosome
may carry antibiotic resistance, VFs
transposons
bacteriophage (phage = virus that infects bacteria) attaches to bacterium and injects its DNA
phage DNA and proteins are repackaged in viral capsids -
some bacterial DNA also be in the viral capsid
new phage injects viral and bacterial DNA into next bacterium
bacterial DNA of virus + host can combine
transduction
sterols in plasma membrane
NO cell wall
mycoplasma (bacteria)
cell wall:
mycolic acid
high lipid content (resistant to gram staining)
mycobacteria
dormant form of bacteria until hospitable environment is available, then replicate again
resist: dessication, heat, cold, disinfectants, lack of nutrients
spores
bacteria that don’t gram stain well
These Microbes May Lack Real Color:
Treponema (G- corkscrew, too small to visualize)
Mycobacteria (high lipid content in cell wall)
Mycoplasma (no cell wall)
Legionella pneumophila (branched fatty acids in cell walls, intracellular)
Rickettsia (intracellular)
Chlamydia (intracellular)
Giemsa stain
Honestly, Certain Bugs Really Try my Patience Histoplasma Chlamydia Borrelia Rickettsiae Trypanosomes my Plasmodium
periodic acid schiff (PAS) stain
PASs the sugar (stains gycogen + mucopolysaccharides) Tropheryma whipplei (Whipple's disease)
ziehl-neelsen stain
stain acid fast organisms:
mycobacterium tuberculosis
india ink stain
encapsualated yeast: cryptococcus neoformans
silver stain
fungi: pneumocystis jirovecii
legionella
provides rigid support to bacterial cell and protects against osmotic pressure differences
peptidoglycan layer of cell wall
spore-forming bacteria when nutrients limited or environment is inhospitable
G+ rods: bacillus, clostridium
others: coxiella burnetti
bacteria has to be in aerobic environment to grow and produce energy
obligate aerobe
obligate aneorobe bacteria
lack catalase and superoxide dismutase:
G+: clostridium tetani, actinomyces
G- rod: bacteroides
antibiotics for aneorbes
metronidazole
clindamycin
causes of neonatal sepsis
GBS E coli (G-) listeria monocytogenes (G+)
organisms most commonly implicated in subacute endocarditis
viridans group streptococci (most common cause of subacute infective endocarditis)
enterococci
s. bovis
coagulase negative staph (s. epidermidis)
HACEK organisms
most common cause of meningitis
s. pneumoniae
most common cause of ostoemyelitis
s. aureus
most common bacterial cause of otitis media in children
s. pneumoniae
cellulitis
s. aureus
s. pyogenes
associated with reactive arthritis (Reiter’s syndrome)
G- diarrhea bugs: shigella salmonella campylobacter jejuni yersinia others: chlamydia trachamotis
infection associated with animal urine
leptospira (spirochete)
hantavirus (rodent urine)
diarrhea after raw eggs or raw chicken
G-:
campylobacter
salmonella
rice water stools
G-:
vibrio cholerae
ETEC
diarrhea from household pet
G- rods:
yersinia enterocolitica
salmonella (reptiles, pet turtles)
blood diarrhea after eating undercooked hamburger meat
EHEC
diarrhea + RLQ pain like appendicitis
yersinia
pregnant women should avoid unpasteurized milk due to these bacteria
listeria
brucella species
coxiella burnetti
most common bacterial cause of cervicitis
chlamydia trachomatis
antibiotic put on eyes after baby is born birth
gonorrhea conjunctivitis
doesn’t treat chlamydia conjunctivitis (use oral azithromycin or erythromycin)
3 main causes of atypical pneumonia (“atypical”)
legionella pneumophila
chlamydophila pneumoniae
mycoplasma pneumoniae
treatment for atypical pneumonia (“walking”)
empiric treatment (don’t look for bug) since antibiotic covers all:
azithromycin
doxycycline
flouroquinolones
bacteria that are non-staining + culture poorly
gardernella vaginalis: bacteria vaginosis
ricketssiae: Giemsa
Ehrlichia chaffeensis: human monocytic ehrlichiosis
Anaplasma phagocytophilum: human granulocytic anaplasmosis
Coxiella burnetti: Q fever
chlamydia species
mycoplasma pneumoniae
if low glucose in CSF fluid consider
bacterial meningitis
tuberculosis meningitis
obligate intracellular bacteria
rickettsia
coxiella
chlamydia
catalase-positive organisms
S. aureus E. coli pseudomonas klebsiella aspergillus salmonella ↑ catalase + infections in chronic granulomatous disease (phagocytes lack free radicals to kill due to no NADPH oxidase)
mycobacteria that causes TB-like symptoms in COPD patients
mycobacterium kansasii
mycobacteria that causes cervical lymphadenitis in children
mycobacteria scrofulaceum
mycobacteria that causes disseminated disease in AIDs patients
MAI or MAC
mycobacteria avium intracellulare
mycobacteria avium complex
mycobacteria that causes hand infection in aquarium
mycobacteria marinum
obligate aerobe bacteria
Nagging Pests Must Breathe Nocardia Pseudomonas aeruginosa Mycobacterium tuberculosis Bacillus
characteristics of enterobacteriaceae in colonic flora
G-, facultative anaerobic bacteria (don’t need O2)
ferment sugar into lactic acid
if excess in colon: can cause lactic acidosis due to absorption
function of MacConkey agar
isolates G- bacteria (crystal violet + bile salts inhibits growth of G+)
distinguish lactose fermenters (pink) from non-lactose fermenters (white)
cell wall inhibitor effective against pseudomonas
3rd or 4th gen cephalosporins
carboxypenicllin (like ticarcillin)
aztreonam
carbapenems
produce urease: hydrolyzes urea → ammonia →↑ pH of urine (more alkaline) → struvite stones (magnesium ammonium phosphate): “staghorn calculus”
proteus mirabilis
klebsiella
