Ew Germs (micro?) Flashcards by Laura Enzinna

microaerophilic

bacteria that can tolerate a little bit of O2

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differential solid culture (def/Eg)

differentiates bac based on characteristics

Eg. Blood agar– hemolytic bac will lyse RBC-visually detectable

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non-selective/nondifferential solid culture

most bac will grow and will not affect the plate/medium; can’t distinguish anything about the bacteria

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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

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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

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What are three ways to identify bacteria on a molecular level?

nucleic acid amplification(PCR), antigen detection, and mass spectrometry

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What are some virulence factors directly involved in pathogenesis?

secreted toxins and enzymes, capsule, cell surface structures

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What are some virulence factors that are indirectly involved in pathogenesis?

siderophores, secretion machinery, catalase, regulatory factors

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Why do bacteria need iron?

They require it for replication.

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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

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What antibiotic is usually used to treat streptococci infections?

penicillin

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Which specific streptococci is the cause of strep throat?

S. pyogenes

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Clostridia is a gram + bacilli. What disease is usually associated with it?

gangrene

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A division of listeria, L. monocytogenes(gram + bacilli) is usually obtained how?

consuming raw dairy products

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Our normal flora is typically composed of what type of bacteria?

anaerobic gram + bacilli

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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)

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What are some physical changes/signs of a gram + infection?

bullous impetigo, draining sinus tract, erythema, fever, murmur, petechiae, superficial abscess, warmth

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Which of the following is hemolytic: staph aureus or staph epidermis?

s. epidermis

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What test can you perform to differentiate between s.aureus and other staph infections?

coagulase test
+ = s.aureus will solidify
- = still liquid

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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)

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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)

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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

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What are three ways to test antibiotic susceptibility?

broth dilution, antimicrobial gradient, disc diffusion

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What antibiotic acts on RNA polymerase?

rifampin

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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