UWorld Chapter 22: Infectious Diseases I

Infection

What is determined by signs and symptoms, including fever, elevated WBC, and site-specific symptoms as well as diagnostic findings, such as culture results, X-rays, and markers of inflammation (e.g. pro calcitonin)?

CNS, meningitis

What *site of infection* is most associated with the following bacteria?

s. pneumoniae

n. meningitidis

h. influenzae

Group B streptococcus/ E. coli (young)

Listeria (young/old)

Upper respiratory

What *site of infection* is most associated with the following bacteria?

s. pyogenes

s. pneumoniae

h. influenzae

m. catarrhalis

Mouth

What *site of infection* is most associated with the following bacteria?

mouth flora (peptoctreptococcus)

anaerobic GNR (prevotella, others)

viridian group streptococci

community lower respiratory

What *site of infection* is most associated with the following bacteria?

s. pneumoniae

h. influenzae

atypical (legionella, mycoplasma, chlamydophila)

enteric GNR (alcohol use disorder)

hospital lower respiratory

What *site of infection* is most associated with the following bacteria?

s. aureus, including MRSA

p. aeruginosa

acinetobacter baumannii

enteric GNR (including ESBL, MDR)

s. pneumoniae

Intra-abdominal

What *site of infection* is most associated with the following bacteria?

enteric GNR

enterococci

streptococci

bactericides species

Heart, endocarditis

What *site of infection* is most associated with the following bacteria?

s. aureus, including MRSA

s. epidermidis

streptococci

enterococci

Skin and Soft Tissue

What *site of infection* is most associated with the following bacteria?

s. aureus

s. epidermidis

s. pyogenes

pasteurella multocida

+/- aerobic/anaerobic GNR (diabetes)

Bone, joint

What *site of infection* is most associated with the following bacteria?

s. aureus

s. epidermidis

streptococci

neisseria gonorrhoeae

GNR (in specific situation)

Urinary tract

What *site of infection* is most associated with the following bacteria?

E. coli

proteus

klebsiella

s. saprophyticus

enterococci

Antibiogram

What can be used to show susceptibility patterns and can be used to monitor resistance trends over time?

Gram positive

What type of organism has a thick cell wall and stains dark purple or blue from crystal violet stain?

Gram negative

What type of organism has a thin cell wall and stain pink due to takin up the safranin counterstain?

Atypicals

What type of organism does NOT have a cell wall and, therefore, does not stain well?

s. aureus

What staphylococcus is coagulase *positive*?

minimum inhibitory concentration (MIC)

What is the term for the minimum concentration of each antibiotic that inhibits bacterial growth?

Gram Positive Rods

What type of organisms are *listeria* and *corynebacterium spp.*?

Gram Positive Cocci

What type of organisms are *staphylococcus, streptococcus, and enterococcus*?

Clusters

How do *staphylococcus* appear differently than other gram positive cocci?

Gram Positive Anaerobes

What type of organisms are *peptostreptococcus, propionibacterium acnes, clostridioides difficile, and clostridium spp.*?

Gram negative Cocci

What type of organism is *neisseria spp.*?

Gram Negative Anaerobes

What type of organisms are *bacterioides fragilis and prevotella spp.*?

Gram Negative Coccobacilli

What type of organisms are *acinetobacter baumanni, bordetella pertussis, and moraxella catarrhalis*?

Enteric Gram Negative Rods

What type of organisms are *proteus mirabilis, E. coli, klebsiella spp., serratia spp. enterobacter cloacae, and citrobacter spp.*?

Non-enteric Gram Negative Rods

What type of organisms are *pseudomonas aeruginosa, h. influenzae, and Providencia spp.*?

Spiral Gram Negative Rods

What type of organisms are *h. pylori, campylobacter spp, treponema spp., borrelia spp., and leptospira spp.*?

Atypicals

What type of organisms are *chlamydia spp, legionella spp, mycoplasma pneumoniae, and mycobacterium tuberculosis*?

Additive

What term describes two antibiotics have an effect equal to the sum of the individual drugs when used concomitantly?

Synergistic

What term describes two antibiotics with an effect greater than the sum of the individual drugs when used concomitantly?

Intrinsic

What *mechanism of resistance* is considered *natural* to the organism? For example, E. coli is resistant to vancomycin because this antibiotic is too large to penetrate the cell wall.

Selection pressure

What *mechanism of resistance* occurs when antibiotics kill susceptible bacteria, leaving behind more resistant strains to multiply? For example, normal GI flora includes enterococcus so when antibiotics (like vancomycin) eliminate susceptible enterococci, vancomycin-resistant enterococcus can become predominant.

Acquired

What mechanism of resistance occurs when bacterial DNA continuing resistant genes can be transferred between species and/or picked up from dead bacterial fragments in the environment?

Antibiotic degradation

What mechanism of resistance occurs when bacterial enzymes break down the antibiotic? For example, beta-lactamases, extended-spectrum beta lactamases, and carbapenem resistant enterobacterales.

Common resistant pathogens

What are the following organisms considered?

*Remember: Kill Each And Every Strong Pathogen*

Klebsiella pneumoniae

Escherichia coli

Acinetobacter baumannii

Enterococcus faecalis, e. faecium

Staphylococcus aureus

Pseudomonas aeruginosa

Concentration dependent

What term defines drugs that can be dosed less frequently and in higher doses in order to maximize the concentration above the MIC, such as aminoglycosides?

Time dependent

What term defines drugs that can be dosed more frequently or each dose can be administered for a longer duration to maximize time above the MIC, such as beta-lactams?

Beta Lactams

What antibiotic class includes penicillins, cephalosporins, and carbapenems and acts by inhibiting bacterial cell wall synthesis by binding to PBPs to prevent the final step of peptidoglycan synthesis in cell walls?

Carbapenems

What beta lactam sub-class is available only in the parenteral form?

Nafcillin and dicloxacillin

What two beta lactams are the only ones that can inhibit the anticoagulant effect of warfarin compared to all others which can enhance the effects?

Enterococcus or atypicals

As a class, what two organism types are cephalosporins NOT active against?

Ceftaroline

What cephalosporin is the only beta-lactam that covers MRSA and is the only one in the 5th generation?

Cefepime

What is the 4th generation cephalosporin which has similar activity to ceftriaxone, but also covers pseudomonas?

Cefuroxime, Cefpodoxime, Cefdinir

What three cephalosporins should be separated from short-acting antacids and avoided with H2RAs and PPIs?

Ceftriaxone

Which cephalosporin may form insoluble precipitates when administered in the same line as calcium-containing IV fluids and is contraindicated in neonates, including at different times of the day?

Ertapenem

What *carbapenem* has *NO* activity against Acinetobacter, pseudomonas, and enterococcus? (*Think APE*)

Aztreonam

What is the only monobactam and has a mechanism of action similar to beta-lactams in that it inhibits bacterial cell wall synthesis by binding to PBPs, but has low potential for cross-reactivity with beta-lactams and, thus, can be used in penicillin allergy?

Aminoglycosides

What antibiotic class includes gentamicin, tobramycin, amikacin, and streptomycin and acts by binding to the ribosome to interfere with bacterial protein synthesis, resulting in a defective bacterial cell membrane?

Extended interval dosing

What dosing strategy for aminoglycosides leads to less accumulation, lower risk of nephrotoxicity, and decreased cost?

Quinolones

What antibiotic class includes ciprofloxacin, levofloxacin, and moxifloxacin and acts by inhibiting bacterial DNA topoisomerase IV and DNA gyrase to prevent supercoiling of DNA and promote breakage of double stranded DNA?

Levofloxacin, Moxifloxacin

What *two* quinolones are considered the *respiratory fluoroquinolone* due to enhanced coverage of *s. pneumoniae and atypicals*?

Moxifloxacin

What is the only quinolones that CAN NOT be used to treat urinary tract infections due to not concentrating in the urine and has no renal dose adjustments?

Ciprofloxacin, Levofloxacin

What *two* quinolones have enhanced gram negative activity, including *pseudomonas*?

Macrolides

What antibiotic class includes azithromycin, clarithromycin, and erythromycin and works by binding the 50S ribosomal subunit to inhibit protein synthesis?

Tetracyclines

What antibiotic drug class includes doxycycline, minocycline, and tetracycline and works by binding the 30S ribosomal subunit to inhibit protein synthesis?

SMX/TMP

What antibiotic contains one part that inhibits dihydrofolic acid formation to interfere in bacterial folic acid synthesis and another part that inhibits dihydrofolic acid reduction to tetrahydrofolate to inhibit the folic acid pathway?

TMP

Based on which component is SMX/TMP dosed?

Vancomycin

What antibiotic is a glycopeptide that inhibits bacterial cell wall synthesis by binding to the D-ala-D-ala cell wall precursor and blocks peptidoglycan polymerization?

Lipoglycopeptides

What antibiotic class includes telavancin, dalbavancin, and oritavancin and inhibits bacterial cell wall synthesis by binding the D-ala-D-ala cell wall precursor AND disrupting bacterial membrane potential and changing cell permeability?

Telavancin

What is the ONLY "vancin" that is approved to treat hospital acquired and ventilator acquired pneumonia in addition to skin and soft tissue infections?

Daptomycin

What antibiotic is a cyclic lipopeptide that bends to cell membrane components to cause rapid depolarization and inhibit all intracellular replication processes and is only active against gram positive organisms, including MRSA and VRE?

Pneumonia

What can daptomycin NOT be used to treat due to being inactivated by surfactant in the lungs?

Linezolid

What oxazolidinone binds to the 50S ribosomal subunit to inhibit translation AND protein synthesis and has activity against MRSA and VRE?

Thrombocytopenia

What side effect is associated with linezolid when it is used for greater than 14 days?

Tigecycline

What broad spectrum antibiotic binds to the *30S ribosomal subunit* to inhibit protein synthesis and has NO activity against Pseudomonas, Proteus, and Providencia?

(*The 3 "P"s*)

Clindamycin

What lincosamide reversibly binds to the *50S ribosomal subunit* to inhibit protein synthesis, has a box warning for *C. difficile* infection, and requires a *D-test* when treating *s. aureus*?

Metronidazole

What antibiotic causes a loss of helical DNA structure and strand breakage resulting in inhibition of protein synthesis and has activity against anaerobes and protozoal organisms?

Rifaximin

What antibiotic inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase, is NOT effective for systemic infections due to low absorption and may result in red-orange urine?

Nitrofurantoin

What antibiotic is a bacterial cell wall, DNA, RNA, and protein synthesis inhibitor that is used for uncomplicated UTIs ONLY and may result in brown urine?

MRSA

For what pathogen are the following antibiotics commonly used?

Vancomycin

Linezolid

Daptomycin

Ceftaroline

SMX/TMP, doxycycline, clindamycin

MSSA

For what pathogen are the following antibiotics commonly used?

Dicloxacillin, nafcillin, oxacillin

Cefazolin, cephalexin

amoxicillin/clavulanate, ampicillin/sulbactam

VRE

For what pathogen are the following antibiotics commonly used?

Pen G or ampicillin (e. faecalis ONLY)

Linezolid

Daptomycin

Cystitis: nitrofurantoin, fosfomycin, doxycyline

ESBL Gram Negative Rods

For what pathogen are the following antibiotics commonly used?

Carbapenems

Ceftazidime/avibactam

Ceftolozane/tazobactam

Gram negative anaerobes (b. fragilis)

For what pathogen are the following antibiotics commonly used?

Metronidazole

Cefotetan, cefoxitin

Beta lactam/ beta lactamase inhibitor

Carbapenems

Moxifloxacin (reduced activity)

Atypical

For what pathogen are the following antibiotics commonly used?

Azithromycin, clarithromycin

Doxycycline, minocycline

Quinolones

Pseudomonas aeruginosa

For what pathogen are the following antibiotics commonly used?

Piperacillin/Tazobactam

Cefepime

Ceftazidime

Carbapenems (NOT ertapenem)

Ciprofloxacin, Levofloxacin

Aztreonam

Tobramycin

IV and Oral doses are the same

What do the following antibiotics have in common?

Azithromycin

Levofloxacin, moxifloxacin

Doxycycline, minocycline

Linezolid

Metronidazole

Doxycycline, Micafungin

What two antimicrobials require light protection during administration?

5% Dextrose

What is the only diluent compatible with SMX/TMP and amphotericin B?

Normal Saline

What is the only diluent compatible with ampicillin, ampicillin/sulbactam, and ertapenem?

Normal Saline or Lactated Ringers

What are the only diluents compatible with caspofungin and daptomycin?

Metronidazole, Moxifloxacin, SMX/TMP

What three antibiotics do NOT require refrigeration in the IV form?