Bacterial Classification Flashcards
What conditions do gram positives prefer?
Dry + Salty
What conditions do gram negatives prefer? Why?
Wet isotonic conditions bc the outside cell membrane is very susceptible to drying out
General speaking, the body becomes ? as you move down
Wetter
Which organs are “wettish”?
Brain + Lungs?
Under what conditions do the lungs get wetter?
Disease, old age, intubation
Where do gram negative cocci tend to invade?
Lungs and up
Where do gram negative bacilli tend to invade?
Lungs down
What are the 4 main gram negative aerobic cocci?
Neisseria meningitidis, Haemophilus influenza, Moraxella catarrhalis and Neisseria gonorrhea
What does Neisseria Meningitidis cause?
Meningitis
What does Haemophilus influenza cause?
Meningitis, otitis media, sinusitis, laryngitis and pneumonia
What does Moraxella catarrhalis cause?
otitis media, sinusitis, laryngitis + pneumonia
What does Neisseria gonorrhea cause?
Penis/vagina infection
What are the gram-negative aerobic cocci causes of meningitis?
Neisseria meningitidis, Haemophilus influenza
What are the gram-negative aerobic cocci causes of otitis media?
Haemophilus influenza, Moraxella catarrhalis
What are the gram-negative aerobic cocci causes of sinusitis and laryngitis?
Haemophilus influenza, Moraxella catarrhalis
What are the gram-negative aerobic cocci causes of pneumonia?
Haemophilus influenza, Moraxella catarrhalis
What are the gram-negative aerobic cocci causes of penis/vagina infections?
Neisseria gonorrhea
What are the most common aerobic gram-negative bacilli organisms?
E. coli; Klebsiella; Intrinsically resistant organisms - “ampC producers”
What acronym is used for nosocomial bacteria?
SPA
What does SPA stand for?
Stenotrophomonas, Pseudomonas, Acinetobacter
What are the 3 most common nosocomial aerobic gram negative bacilli bacterias?
Stenotrophomonas, Pseudomonas, Acinetobacter
What aerobic gram negative bacilli organisms are associated with cat bites?
Pasteurella
What aerobic gram negative bacilli organisms are associated with dog bites?
Pasteurella, Capnocytophaga
What aerobic gram negative bacilli organisms are associated with human bites?
Eikinella
What is the acronym for aerobic gram negative bacilli that cause gastroenteritis?
Very SSPACEY
What are the 8 aerobic gram negative bacilli associated with gastroenteritis?
Vibrio ; Salmonella ; Shigella; Plesiomonas; Aeromonas ; Campylobacter; E. coli ; Yersina
What aerobic gram negative bacilli cause bacterial vaginosis?
Gardnerella
Which gram negative aerobic bacilli cause liver, kidney/bladder, and gut infections?
E.coli ; Klebsiella and ampC producers
What acronym is used for gram negative aerobic bacilli that are intrinsically resistant/amp C producers?
SPICEY HAM
What are the aerobic gram negative bacilli that are intrinsically resistant/amp C producers?
Serratia; Providencia; Indole positive proteus (P. vulgaris); Citrobacter; Enternobacter; Yersinia; Hafnia; Acinetobacter; Morganella
How do ampC producers confer resistance?
Ninja security guards -> Beta lactamases (cut up antibiotics)
How do you determine if an organism metabolizes lactose? What is a positive result?
MacConkey Agar; Turns pink
What is the acronym for gram negative bacilli that ferment lactose?
SEEK Cheese
What are the 5 organisms that metabolize lactose?
Serratia, E.coli, Enterobacter, Klebsiella + Citrobacter
Which ampC producers are also commonly found at hospitals?
Citrobacter, enterobacter, and acinetobacter
Which bacteria are aerobic gram positive cocci in clumps?
Staphylococcus
Which bacteria are aerobic gram positive cocci in chains?
streptococcus and enterococcus
Neisseria meningitidis are
Gram negative aerobic cocci
Haemophilus influenza are
Gram negative aerobic cocci
Moraxella catarrhalis are
Gram negative aerobic cocci
Neisseria gonorrhea are
Gram negative aerobic cocci
E.coli are
Gram negative aerobic bacilli
Klebsiella are
Gram negative aerobic bacilli
ampC producers are
Gram negative aerobic bacilli
Stenotrophomonas are
Nosocomial gram negative aerobic bacilli
Pseudomonas are
Nosocomial gram negative aerobic bacilli
Acinetobacter are
Nosocomial gram negative aerobic bacilli
Pasturella are
Gram negative aerobic bacilli from cat and dog bites
Capnocytophagia are
Gram negative aerobic bacilli from dog bites
Eikinella are
Gram negative aerobic bacilli from human bites
Vibrio are
Gram negative aerobic bacilli that cause gastroenteritis
Salmonella are
Gram negative aerobic bacilli that cause gastroenteritis
Shigella are
Gram negative aerobic bacilli that cause gastroenteritis
Plesiomonas are
Gram negative aerobic bacilli that cause gastroenteritis
Aeromonas are
Gram negative aerobic bacilli that cause gastroenteritis
Campylobacter are
Gram negative aerobic bacilli that cause gastroenteritis
E. coli are
Gram negative aerobic bacilli that cause gastroenteritis
Serratia are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Providencia are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Indole positive proteus (P.vulgaris) are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Citrobacter are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Enterobacter are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Yersinia are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections (gastroenteritis as well)
Hafnia are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Acinetobacter are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
Morganella are
Gram negative aerobic bacilli that are ampC producers and cause liver, kidney, bladder and gut infections
What forms clumps in the context of the catalase test?
Catalase positive aerobic gram positive cocci - Staphylococcus
What forms chains in the context of the catalase test?
Catalase negative aerobic gram positive cocci - Streptococci and Enterococcus
What is the ID of the bacteria that is coagulase positive?
S. aureus - gram positive aerobic catalase positive cocci
What is the ID of the bacteria that is coagulase negative?
CoNS - gram positive aerobic catalase positive cocci
What organism is differentiated using blood agar hemolysis?
Streptococci and enterococci
What organisms show beta hemolysis?
S. pyogenes (group A strep); S. agalactiae (group B strep) and S. dysgalactiae (group c/g)
What organisms show alpha hemolysis?
Viridans group strep
Which organisms are clearly differentiated from from viridians group strep?
S. anginosus and S pneumoniae
Which organisms show gamma hemolysis?
Enterococcus
What is lancefield grouping used for?
Differentiating beta hemolytic streptococci
Group A Strep is
S. pyogenes
Group B Strep is
S. agalactiae
Describe Group C/G strep
a commensal organism of the mouth and a colonizer of the skin and gut
What are the three main categories of gram positive aerobic bacilli?
Bacillus, Corynebacterium and Listeria
B. cereus are
A gram positive aerobic bacilli belonging to bacillus found in soil
B. anthracis are
A gram positive aerobic bacilli belonging to bacillus that secretes toxins that can kill you
C. diphtheriae are
A gram positive aerobic bacilli belonging to corynebacterium
Corynebacterium is …. with the exception of
A commensal aerobic gram positive bacilli ; C.diptheriae is a pathogen
What is the appearance of bacillus?
Large with spores
What is the appearance of listeria?
Small bacilli
What is the appearance of corynebacterium?
Chinese letters
Dr. Stokes calls anaerobic cocci …
Losers
What is the main gram-positive anaerobic cocci?
Peptostreptococcus
Peptostreptococcus are
Gram positive anaerobic cocci
What is the main gram negative anaerobic cocci?
Veilonella
Veilonella are
A gram negative anaerobic cocci
What are the main gram negative anaerobic bacilli?
Fusobacterium, bacteriodes, prevotella, porphyromonas
Fusobacterium are
gram negative anaerobic bacilli
Bacteroides are
gram negative anaerobic bacilli
Prevotella are
gram negative anaerobic bacilli
Porphyromonas are
gram negative anaerobic bacilli
What is the main way to differentiate anaerobic gram positive bacilli?
Spore formation
What is the main spore forming bacteria?
Clostridium spp
What are the main non-spore forming bacteria?
P. acnes (now C. acnes); Actinomyces; Lactobacillus
Clostridium are
spore forming anaerobic gram positive bacilli
C. acnes are
non-spore forming anaerobic gram positive bacilli
Actinomyces are
non-spore forming anaerobic gram positive bacilli
Lactobacillus are
Non spore forming anaerobic gram positive bacilli
What are the most important clostridium species?
C. perfringens, C. difficile, C. tetani and C. botulism
What are the 4 main hints that your patient has an anaerobic infection?
Smelly, low oxygen area (ex - lower colon), signs of necrosis and signs of gas
What gram positive organisms cause food poisoning?
B. cereus, s. aureus and c. perfringens
What are the 5 facultative anaerobes?
Staphylococcus, Enterococcus, Streptococcus, E.coli and Klebsiella
What are the 5 strict (obligate) anaerobes?
Clostridium sp., prevotella, bacteroides, fus-bacterium and bifidobacterium
What are the 2 aerotolerant anaerobes?
Lactobacillus and c. acnes
What does c. acnes look like?
Chinese letters
What does actinomycete look like?
Filamentous -> clumpy chains (sea urchins)
What does fusobacterium look like?
Long thin rods (fusiform)
What are the three main components of bacterial cell walls?
Glycan backbone + NAG + NAM
How to gram positives become resistant?
Changing their PBP structure
How do gram negatives become resistant?
Betalactamases (ninjas)
What are the 5 steps in the gram stain?
Fixation, crystal violet, iodine treatment, decolorization, counter stain with safranin
What are the 2 main categories of gram positive cocci?
Clumps vs chains
What type of bacteria produce gram positive cocci in clumps?
Staphylococcus
What type of bacteria produce gram positive cocci in chains?
Streptococcus and Enterococcus
What does the catalase test differentiate?
Clumps (positive) vs chains (negative)
What does the coagulase test differentiate?
S. aureus vs CoNS
What is the most common presentation of S. aureus?
purulent skin infections
What are non-skin related presentations of S. aureus? Explain the mechanism.
Food poisoning - production of enterotoxin
Toxic Shock Syndrome - production of toxic shock syndrome toxin (TSST-1)
What is the resistance mechanism of MRSA?
Conversion of PBP2 to PBP2a
Describe the pathogenesis of CoNS
Sticks to foreign materials (prosthetic joints, valves)
What is beta-hemolysis?
Full hemolysis (glowey yellow)
What is alpha-hemolysis?
Partial hemolysis (greeny-grey)
What is gamma-hemolysis?
No hemolysis (white ish)
Which bacteria show beta-hemolysis?
S. pyogenes (Group A); S. agalactiae (Group B); S dysgalactiae (Group C/G strep)
What bacteria show alpha-hemolysis?
Viridans group strep including S. anginosus and S. pneumoniae)
Which bacteria show gamma-hemolysis?
Enterococcus
How do you differentiate by the beta-hemolytic strep?
Lancefield grouping
What are the basic features of S. pyogenes?
Get sick fast, colonizer of the upper airways, easily transmissible
What clinical syndromes are associated with S. pyogenes?
Skin/soft tissue, pharyngitis, postpartum fever, rheumatic fever, toxic shock syndrome
What are the basic features of group B strep?
Human commensal, one of the few gram positives found in the gut
What clinical syndromes are associated with S. agalactiae?
Neonatal sepsis; invasive infections in diabetic patients
What is group A strep?
S. pyogenes
What is group B strep?
S. agalactiae
What are the basic features of Group C/G strep?
Human commensal of the mouth (cavities); human colonizer of the skin/gut
What clinical syndromes are associated with Group C/G strep?
Uncommon cause of skin/soft tissue infections; clinical presentation similar to Group A strep
What are the basic features of viridans group strep?
Human commensal of the mouth (can cause cavities); mainly harmless (except S. pneumoniae and S. anginosus)
What clinical syndromes are associated with VGS?
Subacute endocarditis
What are the basic features of S. pneumoniae?
Colonizer of the upper respiratory tract (mouth, nose); Encapsulated
What clinical syndromes are associated with S.pneumoniae
Pneumonia, meningitis and otitis media
What are the basic features of S. anginosus
Human commensal of the upper respiratory tract (mouth and nose) and gut
What are the clinical syndromes associated with S. anginosus?
Look for an abscess; extrovert (only causes infections with its friends the anaerobes)
What are the two main enterococcus species?
E. faecalis and E. faecium
What are the basic features of Enterococci?
Commensal of the gut; somewhat resistant
What clinical syndromes are associated with Enterococci?
UTIs, relatively sticky -> don’t want it in the blood esp. with synthetics
What features make Enterococci more resistant?
Multiple kinds of PBPs, picks up folate from the environment (like humans), Can mutate not only its PBP but also the side chains in the peptidoglycan layer
What is special about E. faecium?
It has a mutated PBP like MRSA
What is VRE?
Vancomycin resistant Enterococcus - has a mutated PBP and a mutated side chain
What aerobic gram positive cocci cause UTIs?
Enterococcus and S. saprophyticus (CoNS)
Which aerobic gram-positive cocci cause skin infections?
Group A strep (S. pyogenes), Group C/G strep (S. dysgalctaie), S. aureus
What is group C/G strep?
S. dysgalactiae
What aerobic gram-positive cocci are found in the gut?
Enterococcus, Group B strep, Group C/G strep (small amounts), S. anginosus
What aerobic gram-positive cocci can be found naturally in the upper airway?
VGS including S. anginosus; Group C/G strep
What aerobic gram-positive cocci can be found naturally on the skin?
CoNS
What should you do if you encounter S. aureus bacteremia?
Consult ID!
What are the most common gram positive bacilli in the hospital?
Corynebacterium or anaerobes
What are the basic features of aerobic gram positive bacilli?
Produce crazy toxins that can kill you; may produce spores
What are the basic features of Bacillus?
Aerobic, spore forming, GPB
What are the two most important Bacillus species?
B. cereus and B. anthracis
What are the basic features of B. cereus?
Found in soil
What clinical syndromes are associated with B. cereus?
Post traumatic infections (esp of the eyeballs), secrete toxins that cause food poisoning (esp. fried rice)
What are the basic features of B. anthracis?
Found in diseased animals, secretes deadly toxins
What clinical syndromes are associated with B. anthracis?
Death…
What are the basic features of corynebacterium
Common skin commensal, mainly non-pathogenic with the exception of C. diphtherie?
B. cereus are
Spore forming aerobic GPB belonging to Bacillus; pathogenic
B. anthrax’s are
Spore forming aerobic GPB belonging to Bacillus; pathogenic
Corynebacterium are
Aerobic GPB; commensal
What are the basic features of C. diptheriae
Found in soil; transmissible via contact/droplet; we have vaccines!
What clinical syndromes are associated with C. diphtheriae?
Respiratory/cutaneous disease from toxins that destroy organs
C. diphtheriae are
Aerobic GPB belonging to Corynebacterium; pathogenic
What are the basic features of Listeria
Found in soil, acquired from contaminated food (can grow in the fridge)
What clinical syndromes are associated with Listeria?
Gastroenteritis in immunocompetent; Meningitis in neonates, elderly, immunocompromised and pregnant women
Listeria are
Aerobic GPB; pathogenic
What do Bacillus sp. look like?
Box cars -> big and in little pairs
What do corynebacterium look like?
Chinese characters
What do Listeria look like?
Small bacilli
What is an important part of the detoxification pathway in aerobic bacteria?
Catalase
What is a normal anaerobic flora of the skin?
Propionibacterium
What is a normal anaerobic flora of the gut?
Peptostreptococcus, Clostridium, Bifidobacterium and Bacteroides
What is a normal anaerobic flora of the mouth?
Actinomyces, Prevotella and Fusobacterium
What is a normal anaerobic flora of the UGT?
Lactobacillus
What are the 4 hints than an infection is caused by anaerobes?
Smelly, oxygen poor environment, necrosis, gas
What are the loser anaerobes?
Cocci
What is the main gram positive anaerobic cocci?
Peptostreptococcus
What is the main gram negative anaerobic cocci?
Veilonella
Peprostreptococcus are
Gram positive anaerobic cocci
Veilonella are
Gram negative anaerobic cocci
What are the 4 main gram negative anaerobic bacilli?
Fusobacterium, Bacteroides, Prevotela and Porphyromonas
What are the two main species of Fusobacterium?
F. nucleatum and F. necrophorum
Fusobacterium are
Anaerobic gram negative bacilli
F. nucleatum are
Anaerobic gram negative bacilli
F. necrophorum are
Anaerobic gram negative bacilli
What clinical syndromes are associated with Fusiform bacteria?
Anaerobic infections of the upper airway
Bacteroides are
Anaerobic gram negative bacilli
Prevotella are
Anaerobic gram negative bacilli
Porphyromonas are
Anaerobic gram negative bacilli
What are the main organisms associated with anaerobic gut infections?
Bacteroides, Prevotella and Porphyromonas
What are the two main classifications of anaerobic gram positive bacilli?
Spore forming vs no spores
What is the main group of spore forming bacteria?
Clostridium
C. perfringens are
spore forming anaerobic gram positive bacteria
C. difficile are
spore forming anaerobic gram positive bacteria
C. tetani are
spore forming anaerobic gram positive bacteria
C. botulinum are
spore forming anaerobic gram positive bacteria
What are the basic features of Clostridium spp.
Spore forming, strict anaerobes that are found in the environment and produce toxins that kill you
What are the basic features of C. perfringens?
Human commensal in the gut
What clinical syndromes are associated with C. perfringens?
Enterotoxin -> food poisoning of meats + poultry
Alpha toxin -> gas gangrene
What are the basic features of C. difficile?
Found in soil; nosocomial pathogen; needs extra cleaning to kill spores; proliferates in the presence of antibiotics
What clinical syndromes are associated with C. difficile?
Makes toxins A + B which cause massive inflammation of the large intestine causing it to burst
What is the mechanism of C. tetani?
Toxin of the CNS that inhibits inhibitory neurons
What is the mechanism of C. botulism?
Toxin of the PNS that inhibits neurons that tell the body to move
Where are C. tetani and C. botulism found?
Soil
What are the main non-spore forming anaerobic gram positive bacilli?
C. acnes, Actinomyces and Lactobacillus
C/P. acnes are
non-spore forming anaerobic gram positive bacilli
Lactobacillus are
non-spore forming anaerobic gram positive bacilli
Actinomyces are
non-spore forming anaerobic gram positive bacilli
What are the basic features of Lactobacillus?
Human commensal of the gut/vagina, aerotolerant, common in probiotics, rarely pathogenic
What are the basic features of Actinomyces?
Human commensal of the upper airways, gut and vagina; mostly facultative anaerobes but main one is a strict anaerobe
What does Actinomyces look like?
Clumpy + filamentous
What clinical syndromes are associated with Actinomyces? Which species causes it?
Actinomycosis caused by A. israelii -> described as sulfur granules
A. Israelii are
Non spore forming anaerobic gram positive bacilli
What are the basic features of C. acnes?
Human commensal of the skin that causes acne; aerotolerant
What does C. acnes look like?
Corynebacterium (chinese letters)
What clinical syndromes are associated with C. acnes?
Similar to CoNS; seems to target artificial shoulder joints
When do bacteria produce spores?
Under unfavourable conditions
What are 5 things spores are resistant to?
Time, hand sanitizer, boiling, dehydration and radiation
What gram positive organisms cause food poisoning?
B. cereus, S. aureus, C. perfringens
How is food poisoning different from gastroenteritis?
Ingest the toxins not the organism -> faster onset (<6 hours) because the organism doesn’t have to grow
Whare are 5 facultative anaerobes?
Staphylococcus, Enterococcus, Streptococcus, E.coli and Klebsiella
What are 5 strict anaerobes?
Clostridium, Prevotella, Bacreroides, Fusobacterium and Bifidobacterium
What are 2 aerotolerant anaerobes?
Lactobacillus and C. acnes
What is the genus of C. acnes?
Cutibacterium