Ew Germs (micro?) Flashcards
microaerophilic
bacteria that can tolerate a little bit of O2
differential solid culture (def/Eg)
differentiates bac based on characteristics
Eg. Blood agar– hemolytic bac will lyse RBC-visually detectable
non-selective/nondifferential solid culture
most bac will grow and will not affect the plate/medium; can’t distinguish anything about the bacteria
selective solid culture (def/Eg)
represses the growth of some bac while allowing others to grow; can make it so only certain bac will grow
Eg. Thayer-Martin Medium–> Neisseria only
selective and differential solid culture (def/Eg)
lets only certain bac grow and can select for a change in the medium that will indicate a trait about bac
Eg. MacConkey–> gram-negative grow(yellow) and bac that are able to ferment lactose will turn medium pink
s: gram-negative
d: able to ferment lactose
What are three ways to identify bacteria on a molecular level?
nucleic acid amplification(PCR), antigen detection, and mass spectrometry
What are some virulence factors directly involved in pathogenesis?
secreted toxins and enzymes, capsule, cell surface structures
What are some virulence factors that are indirectly involved in pathogenesis?
siderophores, secretion machinery, catalase, regulatory factors
Why do bacteria need iron?
They require it for replication.
If you have a gram + cocci bacteria, how can you tell if it is staphylococci or streptococci? What does this test do?
catalase test = enzyme catalase will break down hydrogen peroxide into O2
+ = bubbles
- = no rxn
What antibiotic is usually used to treat streptococci infections?
penicillin
Which specific streptococci is the cause of strep throat?
S. pyogenes
Clostridia is a gram + bacilli. What disease is usually associated with it?
gangrene
A division of listeria, L. monocytogenes(gram + bacilli) is usually obtained how?
consuming raw dairy products
Our normal flora is typically composed of what type of bacteria?
anaerobic gram + bacilli
What laboratory tests would be helpful if a gram + organism is suspected?
CBC, electrolytes, blood cultures, pro-calcitonin levels, echocardiogram(endocarditis suspected), joint aspiration(septic joint is suspected)
What are some physical changes/signs of a gram + infection?
bullous impetigo, draining sinus tract, erythema, fever, murmur, petechiae, superficial abscess, warmth
Which of the following is hemolytic: staph aureus or staph epidermis?
s. epidermis
What test can you perform to differentiate between s.aureus and other staph infections?
coagulase test
+ = s.aureus will solidify
- = still liquid
What diseases are commonly associated with staph aureus?
superficial lesions(wound infection), toxinoses(food poisoning, scaled skin syndrome, toxic shock syndrome) life-threatening(endocarditis, osteomyelitis, pneumonia, brain abscess, meningitis, bacteremia)
What virulence factors does staph aureus have?
adherence factors (adhesins that allow bac to attach to cells/can be specific adhesins for specific cell types) and exoproteins(exotoxins)
What are three main ways that staph aureus evades or uses the immune system to be infectious?
activation of T lymphocytes and the formation of superantigens
release of toxins that induce host cell lysis
secretes factors that inhibit neutrophil recruitment
What are three ways to test antibiotic susceptibility?
broth dilution, antimicrobial gradient, disc diffusion
What antibiotic acts on RNA polymerase?
rifampin
What antibiotic acts on DNA gyrase?
quinolones
What antibiotics act on folate synthesis?
sulfonamides and trimethoprim
What antibiotics act on beta-lactam?
penicillins, cephalosporins, carbapenems, monobactams
What antibiotics act on the cell wall?
vancomycin and bacitracin
What antibiotics act on the cell membrane?
polymyxins
What antibiotics act on the 50s subunit?
macrolides, clindamycin, linezolid, chloramphenicol, and streptogramins
What antibiotics inhibit protein synthesis?
aminoglycosides, chloramphenicol, macrolides, streptothricin, tetracycline
What antibiotics inhibit DNA and RNA synthesis?
quinolones and rifampin
What antibiotics interfere with the cell wall?
beta-lactams and glycopeptides
What antibiotics inhibit energy metabolism?
sulfonamides and trimethoprim
What are some mechanisms of antibiotic resistance?
permeability changes, active efflux, enzymatic modification, degradation, acquisition of an alternate metabolic pathway, modification of antibiotic target, overproduction of target enzyme
How can bacteria gain antibiotic-resistant genes?
chromosomal mutations, transformation, transfer/acquisition of new genetic material
Why are biofilms so bad?
aggregates of bac are resistant to antibiotics and phagocytes
What are four ways to classify streptococcus species?
colony morphology, hemolysis, biochemical rxns, serologic specificity
Streptococcus pygenes symptoms/signs/diseases
pharyngitis, scarlet fever, impetigo, cellulitis, erysipelas, invasive infections, immune-mediated sequelae
Streptococcus pneumoniae signs/symptoms/diseases
pneumonia, meningitis, occult bacteremia
S. pneumoniae detection?
beta-hemolysis, P disc sensitive(optochin sensitive aka inhibits growth), gram + cocci
Strep. agalactiae
neonates= meningitis, spesis, pneumonia adults= vaginitis, puerperal fever, UTI, skin infection, endocarditis
Viridans streptococci
endocarditis
Enterococcus
UTI and biliary tract infections
Which gram + bacilli are spore formers?
clostridia, bacillus(B. anthracis and B. cereus)
What makes spores advantageous?
makes bac environmentally resistant, can stay inert until growing conditions are good
Example of an anerobe
clostridium perfringens–> causes gas gangrene or soft tissue infections
Gram-negative bacteria will stain ____
pink
What are two main types of gram - cocci?
Neisseria and Moraxella
Niesseria is oxidase _______ and catalase _______
+;+
Thayer-Martin is a SELECTIVE media used to select for _______
Neisseria–> gonorrhoeae and meningitidis; TM agar inhibits the growth of the normal flora
What are eight types of gram - bacilli?
haemophillus, aggregatibacter, actinobacillus, and pasturella, pseudomonas, burkholderia, stenotrophomonas, acinetobacter
What gram characteristic and shape is enterobacteriaceae?
gram - bacilli
food poisoning, UTIs, gastroenteritis, and newborn meningitis are all associated with which gram-negative bacteria?
escherichia coli aka E. coli
lung and UTIs are associated with which gram - bacteria?
Pseudomonas aeruginosa
meningitis, lung infections, UTIs, and bloodstream infections are all associated with which gram - bacteria?
Klebsiella
several types of infections in wounded soldiers are associated with which gram - bacteria?
Acinetobacter baumannii
UTIs, lung infections, bloodstream infections, and food poisoning are all associated with which gram - bacteria?
Enterobacteriaceae
What is the most common risk factor for gram - bacterial infections?
hospitalization
What factors can increase the risk of bacterial infections?
recent surgery, use of a urinary catheter, war wounds, dialysis, use of a mechanical ventilator, weakend immune system
Although symptoms of bacterial infection usually depend on location, ______ is a common sign.
fever
What are some fluid tests you can run to identify bacteria?
blood tests/culture, urine tests/culture, sputum samples, stool samples, lumbar puncture, cultures of abscesses, skin lesions, wounds
What are some ways to ensure a good specimen collection?
avoid contamination, provide an adequate volume of material, collected before antimicrobial therapy, proper/appropriate labels, transported in a timely manner
What does MacConkey agar use to restrict growth to gram - bacteria?
bile salts
Why are Enterotubes so cool?
you can do multiple tests on a sample at once
What are two types of gram - spiral-shaped bacteria?
campylobacteraceae and helicobacteraceae
gram - bacilli = Bordetella pertussis
whooping cough
gram - bacilli = Brucella
brucellosis
gram - bacilli = Francisella tularensis
tularemia
Legionella pneumophilia
pneumonia, Legionnaire’s disease
gram - bacilli = Bartonella
bartonellosis
gram - bacilli = vibrio
vibriosis
Moraxella catarrhalis causes …
3rd leading cause of bacterial ear infections in children and a variety of upper respiratory tract infections in adults (some respiratory exacerbations in pts with COPD)
gram - bacilli = serratia marcescens
UTI, pneumonia, wound infections, skin and soft tissue infections, surgical site infection, bloodstream infections
Risk factors: immunosuppression, previous antimicrobial agents, indwelling endocarditis
gram - bacilli = hemophilus influenzae
the primary cause of acute epiglottitis
