Microorganisms Overview

Question 1

Staphylococci

Answer 1

• Aerobic, Gram (+)

- ex.) S. aureus, S. epidermis

Question 2

Streptococci

Answer 2

• Aerobic, Gram (+)
• ex.) S. pyogenes, S. pneumoniae, S. viridans
• strep do not make beta-lactamases so we can use old school penicillins on them
• S. pyogenes causes strep throat

Question 3

Enterococci

Answer 3

• Aerobic, Gram (+)

- ex.) E. faecalis, E. faecium

Question 4

Clostridium

Answer 4

• Anaerobic, Gram (+)

- ex.) C. tetanus, C. perfringens, C. difficile

Question 5

Enterobacteriaceae

Answer 5

• Aerobic, Gram (-)
• ex.) E. coli, Protous, Klobsiella, Salmonella
• E. coli is the most common cause of UTIs

Question 6

Pseudomonas

Answer 6

• Aerobic, Gram (-)

- ex.)P. aeruginosa

Question 7

Acinetobater

Answer 7

• Aerobic, Gram (-)

- ex) A. baumannii

Question 8

Hemophilus

Answer 8

• Aerobic, Gram (-)

- ex) H. influenza

Question 9

Neisseria

Answer 9

• Aerobic, Gram (-)

- ex.)N. gonorrhoeae, N. menigitides

Question 10

Bacteroides

Answer 10

• Anaerobic, Gram (-)
• B. fragilis
• Biggest anaerobie in the GI tract (the farther down you go the more you’ll see)

Question 11

Legionella

Answer 11

• Atypicals

- ex.) L. pneumophila

Question 12

Chlamydia

Answer 12

• Atypical

- ex.) C. pneumnia, C. trachomatis

Question 13

Mycoplasma

Answer 13

• Atypical

- ex.) M. pneumoniae

Question 14

Stapylococcus aureus

Answer 14

• Gram (+) cocci in clusters
• Methicillin resistance attributed to mecA gene
• 2 major MRSA categories: Healthcare-associated, and Community-associated

Question 15

Streptococcus pneumoniae

Answer 15

• Gram (+) cocci in pairs & chains
• Normal sinus colonizer in some
• encapsulated
• increasing resistance to Macorlides, beta-lactams, and fluoroquinolones
• Can cause: CAP, bacterial menigitis, most common pathogen in respiratory infections, sinusitis, Otitis media, etc

Question 16

Streptococcus pyogenes

Answer 16

• Gram (+) cocci in pairs and chains
• aka: Group A strep (GAS), flesh eating bacteria
• toxin producer
• Still sensitive to PCN
• Common cause of: strep throat, toxic shock syndrome, skin/skin structure infections

Question 17

Enterococcus faecalis, Enterococcus faecium

Answer 17

• Gram (+) cocci in pairs and chains
• Normal flora of GI tract, skin, mouth
• E. faecalis is less resistant than E. faecium ( VRE is more often E. faecium)
• usually working with something else when causing a serious infection
• common cause of: Nosocomia bacteremia, endocarditis, UTI, and wound infections

Question 18

Neisseria sp.

Answer 18

• Gram (-) cocci, encapsulated
• Neisseria menigitides – 2nd most common pathogen in bacterial meningitis, Small % have this in sinus cavity, passed by exchange of saliva or respiratory secretions (vaccine available)
• Neisseria gonorrhoeae– gonorrhea, not normal flora

Question 19

E. Coli & Klebsiella

Answer 19

• Gram (-) rod
• E.coli is the most common aerobic bacteria in GI tract
• Common cause of: UTIs (E. coli), bacteremia, intra-abdominal wound, HAP
• two most common producers of ESBL

Question 20

Pseudomonas aeruginosa

Answer 20

• Gram (-) rod
• outside of hospital found in soil or water (only very sick patients get it)
• Not normal flora
• Colonization can happen in hospitalized patients (Chronic ventilator patients, indwelling catheters or g-tubes)
• Common cause: HAP (2nd leading pathogen to MRSA), bacteremia, wound infections, post-op infections, UTI

Question 21

SPACE

Answer 21

• producers of ampC beta-lactamases (deactivates ALL beta-lactams except cefepime & carbapenems)
• S-serratia, P- proteus, pseudomonas, A- acinetobacter, C- citrobacter, E- enterobacter