Infectious Diseases I Flashcards
What are transmissible diseases that are spread from person to person referred to?
Communicable or contagious
What are three primary factors that impact treatment decisions in infectious diseases?
The bug (pathogen), the drug (antibiotic) and the patient (host)
What do infection characteristics include?
The infection site, infection severity and whether it is community- or hospital-acquired
*Infections that are hospital-acquired often involve MDR organisms
How is the presence of an infection determined by?
By signs and symptoms
What do antibiotic characteristics include?
The spectrum of activity and ability to penetrate the site of infection
What are some patient characteristics that impact treatment choices?
Age, body weight, renal and hepatic function, allergies, recent antibiotic use, colonization with resistant bacteria, recent environmental exposure, vaccination status, pregnancy status, immune function and comorbid conditions
What is considered when initiating empiric treatment?
This empiric treatment is usually broad-spectrum (covers several different types of bacteria) and is based on a best guess of the likely organisms causing the infection. Local resistance patterns and antibiotic use guidelines should be considered when selecting empiric treatment
What are some common bacterial pathogens for CNS/meningitis?
Streptococcus pneumoniae, neisseria meningitis, Haemophilus influenzae, group B streptococcus/e. coli (young), listeria (young/old)
What are some common bacterial pathogens for upper respiratory?
Streptococcus pyogenes, streptococcus pneumoniae, haemophilus influenzae, moraxella catarrhalis
What are some common bacterial pathogens for heart/endocarditis?
Staphylococcus aureus, streptococcus pyogenes, staphylococcus epidermidis, pasteureall multocida
What are some common bacterial pathogens for bone/joint?
Staphylococcus aureus, staphylococcus epidermidis, streptococci, neiserria gonorrhoeae, GNR
What are some common bacterial pathogens for mouth?
Mouth flora, anaerobic GNR, viridans group Streptococci
What are some common bacterial pathogens for lower respiratory?
Streptococcus pneumoniae, haemophilus influenzae, atypicals (legionella, mycoplasma), chlamydophilia, enteric GNR (alcoholics)
What are some common bacterial pathogens for lower respiratory?
Staphyloccocus aureus, including MRSA, pseudomonas aeruginasa, acinetobacter bamannii, enteric GNR (including ESBL, MDR), streptococcus pneumoniae
What are some common bacterial pathogens for urinary tract?
E. coli, proteus, klebsiella, staphylococcus saprophyticus enterococci
What is the purpose of the gram stain?
The Gram stain categorizes the organism by shape and provides quick, preliminary results. It provides a clue about what organism may be causing the infection ad an opportunity to adjust the empiric antibiotic regimen before the species is formally identified
Describe gram-positive organisms
Have a thick cell wall and stain dark purple or bluish from the crystal violet stain
*Staphylococcus (including MRSA, MSSA), step pneumoniae, streptococcus, enterococcus, listeria monocytogenes, corynebacterium, peptostreptococcus, propionbacterium acnes, clostridiodes
Describe gram-negative organisms
Have a thin cell wall and take up the safranin counterstain, resulting in a pink or reddish color
*Includes Neisseria spp, proteus mirabilis, e coli, klebsiella, serratia, enterobacter, citrobacter, acinetobacter, bordetella, moraxella, pseudomonas, haemophilus influenzae, providencia
Describe atypical organisms
Do not have a cell wall and do not stain well
*Includes: chlamydia supp., legionella spp, mycoplasma pneumoniae, mycobacterium tuberculosis
What does an antibiogram show?
An antibiogram combines culture data from patients at a single institution into one chart to show susceptibility patterns over a specific time period (generally 1 year). Antibiograms aid in selecting empiric treatment and are used to monitor resistance trends over time
How soon is a culture and susceptibility report usually available?
Within 24-72 hours
What is the purpose of C&S report?
The C&S report identifies the organism and the results of the susceptibility testing. The empiric antibiotics can then be streamlined, which can include discontinuing one or more antibiotics and/or changing to a more narrow-spectrum treatment
What is the minimum inhibitory concentration (MIC)?
The minimum concentration of each antibiotic that inhibits bacterial growth. MICs are specific to each antibiotic and organism and should not be compared among different antibiotics
What is the susceptibility breakpoint?
The usual drug concentration that inhibits bacterial growth
What can the effect of two antibiotics cause?
The effect of two additive antibiotics can be additive (an effect equal to the sum of the individual drugs) or synergistic (an effect greater than the sum of the individual drugs)
What are the steps and approach to prescribing antibiotic treatment?
1) Empiric treatment: select empiric treatment based on the likely organisms at the infection site
2) Streamline: when the C&S results are available, streamline to more narrow-spectrum antibiotics as soon as possible
3) Assess the patient: monitor for improvement and patient’s condition
How can you monitor treatment response?
- Clinical status: fever trend and other vital signs depending on the infection, WBC trend, reduction in signs and symptoms of infection
- Radiographic findings (such as chest x-ray results)
- Repeat cultures negative
- Decreased markers of inflammation: procalcitonin levels, C-reactive protein and erythrocyte sedimentation rate
What are some reasons for lack of response of treatment?
- Antibiotic factors: inadequate spectrum and/or dose, poor tissue penetration, drug-drug interactions, non-adherence, inadequate duration of treatment, inability to tolerate/toxicity
- Microbiologic factors: resistance, superinfection (C. difficile), alternative etiology
- Host factors: uncontrolled source of infection, immunocompromisedq
What is antibiotic resistance?
Antibiotic resistance is the ability of an organism to multiply in the presence of a drug that normally limits its growth or kills it. These infections are difficult to treat ad often require drugs that are costly and/or toxic
What are common mechanisms of resistance?
Intrinsic resistance, selection pressure, acquired resistance, enzyme inactivation
Describe intrinsic reistance
The resistance is natural to the organism
Describe selection pressure
Resistance occurs when antibiotics kill off susceptible bacteria, leaving behind more resistant strains to multiplyf
Describe acquired resistance
Bacterial DNA containing resistant genes can be transferred between different species and/or picked up from dead bacterial fragments
Describe enzyme inactivation
Enzymes produced by bacteria break down the antibiotic
What are some examples to combat enzyme inactivation of antibiotics?
- Bacteria that product beta-lactamases break down beta-lactams before they can bind to their site of activity. Beta-lactamase inhibitors are combined with some beta-lactams to preserve or increase their spectrum of activity
- ESBLs are beta-lactamases that can break down all penicillins and most cephalosporins. Organisms that produce ESBLs can be difficult to kill, and serious infections involving these organisms are treated with carbapenems or newer cephalosporin/beta-lactamase inhibitors
- Carbapenem-resistant Enterobacteriaceae are MDR gram-negative organisms that produce enzymes capable of breakdown penicillins, most cephalosporins and carabpenems. CRE infections typically require treatment with a combination of antibiotics that include drugs such as the polymyxins, which have a high risk for toxicity
What are some common resistant pathogens?
- Klebsiella pneumoniae (ESBL, CRE)
- Escherichia coli (ESBL, CRE)
- Acinetobacter baumannii
- Enterococcus faecalis, enterococcus faecium (VRE)
- Staphyloccocus aureus (MRSA)
- Pseudomonas aeruginosa
What is the pathophysiology of clostridiodes difficile infection?
Antibiotics kill normal, healthy GI flora along with pathogens they are targeting, which results in overgrowth of drug-resistant organisms and can lead to superinfections such as C diff. Inactive C diff spores are present in normal GI flora. When an antibiotic kills off the normal flora, C. diff spores can become activated, producing toxins that inflame the GI mucosa
What are some symptoms of C. diff?
Symptoms can be mild (loose stools and abdominal cramping) to severe (pseudomembranous colitis that can require colectomy and can be fatal)
Which antibiotics have the highest risk of CDI?
All antibiotics have a warning for the risk of CDI, but the risk is highest with broad-spectrum penicillins and cephalosporins, quinolones, carbapenems and clindamycin (which has a boxed warning)
What is the purpose of antimicrobial stewardship programs (ASPs)?
Designed to improve patient safety and outcomes, curb resistance, reduce adverse effects and promote cost-effectiveness
What do ASPs do?
ASPs consist of collaborative teams that establish antibiotic guidance for their facility. ASPs conduct audits of prescribing habits and provide education to change suboptimal practices and improv care
What are some examples of ASP interventions?
Pharmacokinetic monitoring of aminoglycosides and vancomycin, use of clinical decision support software to rapidly identify pathogens and shorten the time to starting effective treatment, preauthorization of select antimicrobials, prospective audit and feedback to prescribers of selected antibiotics and timely transitions from IV to PO antibiotics
What are the general antibiotic mechanisms of action?
Generally, cell wall and cell membrane inhibitors, DNA/RNA inhibitors and aminoglycosides are bactericidal (kill bacteria), while most protein and folic acid synthesis inhibitors are bacteriostatic (inhibit bacterial growth)
What are some examples of DNA/RNA inhibitors?
Quinolones (DNA gyrase, topoisomeraise IV), Metronidazole, tinidazole, rifampin
What are some examples of folic acid inhibitors?
Sulfonamides, trimethoprim, Dapsone
What are some examples of cell wall inhibitors?
Beta-lactams (penicillins, cephalosporin, carbapenems), monobactams (aztreonam), vancomycin, dalbavancin, telavancin, oritavancin
What are some examples of protein synthesis inhibitors?
Aminoglycosides, macrolides, tetracyclines, clindamycin, linezolid, tedizolid, quinupristin/dalfopristin
What are some examples of cell membrane inhibitors?
Polymyxins, daptomycin, telavancin, oritavancin
What are some examples of hydrophilic agents?
Beta-lactams, aminoglycosides, glycopeptides, daptomycin, polymyxins
What are some PK parameters considered with hydrophilic agents?
1) Small distribution: poor tissue penetration
2) Renal elimination: drug accumulation and side effects can occur if not dose adjusted
3) Low intracellular concentrations: not active against atypical (intracellular) pathogens
4) Increased clearance and/or distribution in sepsis: consider loading doses and aggressive dosing in sepsis
5) Poor-moderate bioavailability: not used PO or IV:PO ratio is not 1:1
What are some examples of lipophilic agents?
Quinolones, Macrolides, Rifampin, Linezolid, Tetracyclines
What are some PK parameters considered with lipophilic agents?
1) Large volume of distribution: excellent tissue penetration (including bone, lung and brain tissues)
2) Hepatic metabolism: potential for hepatotoxicity and drug-drug interactions
3) Achieve intracellular concentrations: active against atypical (intracellular) pathogens
4) Clearance/distribution is changed minimally in sepsis: dose adjustments generally not needed in sepsis
5) Excellent bioavailability: IV:PO ratio is often 1:1
How can drugs with concentration-dependent killing be dose optimized?
Can be dosed less frequently and in higher doses to maximize the concentration above the MIC
How can drugs with time-dependent killing be dose optimized?
Can be dosed more frequently or administered for a longer duration to maximize the time above the MIC
What are some examples of antibiotics that are concentration-dependent?
Aminoglycosides, quinolones, daptomycin
What are some examples of antibiotics that are exposure-dependent?
Vancomycin, macrolides, tetracyclines, polymyxins
What are some examples of antibiotics that are time-dependent?
Beta-lactams (penicillins, cephalosporins, carbapenems)
What is the MOA of beta-lactam antibiotics?
Beta-lactam have a chemical structure that is characterized by a beta-lactam ring. They inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) which prevents the final step of peptidoglycan synthesis in bacterial cell walls
What bacteria are penicillins not active against?
Atypicals or MRSA
What are natural penicillins active against?
Natural penicillins are active against Gram-positive cocci (Streptococci and Enterococci; they do not cover Staphylococci) and Gram-positive anaerobes (mouth flora). They have no appreciable Gram-negative activity
What do antistaphylococcal penicillins cover?
Streptococci and have enhanced activity against methicillin-susceptible Staphylococcus aureus (MSSA), but they lack activity against Enterococcus, gram-negative pathogens and anaerobes
What do aminopenicillins cover?
Aminopenicillins cover Streptococci, Enterococci and gram-positive anaerobes (mouth flora) plus (with the addition of the amino group) the gram-negative bacteria Haemophilus, Neisseria, Proteus and E. coli
*Aminopenicllins combined with beta-lactamase inhibitors have added activity against MSSA, more resistant strains of gram-negative bacteria and gram-negative anaerobes
What do extended-spectrum penicillins, combined with a beta-lactamase inhbitor cover?
Broad spectrum activity: cover same organisms as aminopenicillin/beta-lactamase inhibitor combinations plus have expanded coverage of other gram-negative bacteria, including Citrobacter, Acinetobacter, Providencia, Enterobacter, Serrata and Pseudomonas aeruginosa
What are some examples of natural penicillins?
Penicillin V potassium, Penicillin G aqueous, Penicillin G Benzathin
What are some examples of antistaphylococcal penicillins?
Dicloxacillin, Naficillin, Oxacillin
What are some examples of aminopenicillins?
Amoxicillin, Augmentin, Ampicillin, Unasyn
What are some examples of extended-spectrum penicillins?
Piperacillin/Tazobactam (Zosyn)
What is a boxed warning associated with penicillins?
Penicillin G benzathine: not for IV use; can cause cardio-respiratory arrest and death
What are some contraindications within the penicillin class?
- Augmentin and Unasyn: history of cholestatic jaundice or hepatic dysfunction associated with previous use
- Severe renal impairment (CrCL < 30 mL/min): do not use extended-release oral forms of amoxicillin and Augmentin XR or the 875 mg strength of augmentin
What are some side effects of penicillins?
Seizures (with accumulation when not correctly dose adjusted in renal dysfunction), GI upset, diarrhea, rash (including SJS/TEN)/allergic reactions/anaphylaxis, hemolytic anemia (identified with a positive Coombs test), renal failure, myelosuppression with prolonged use, increased LFTs
What are some monitoring parameters of penicillins?
Renal function, symptoms of anaphylaxis with the first dose, CBC and LFTs with prolonged courses
What are some notes about antistaphylococcal penicillins?
- Preferred for MSSA soft tissue, bone and joint, endocarditis and bloodstream infections
- No renal dose adjustments
- Nafcillin is a vesicant: administration through a central line is preferred; if extravasation occurs, use cold packs and hyaluronidase injections
What are some notes about aminopenicillins?
- Aminopenicillin PO is rarely used due to poor bioavailability; amoxicillin is preferred if switching from IV ampicillin
- Amoxicillin/clavulanate: use a 14:1 ratio to decrease diarrhea caused by the clavulanate component
- IV ampicillin and ampicillin/sulbactam must be diluted in NS only
What is a note about extended-spectrum penicillins?
Piperacillin/tazobactam contains 65 mg Na per 1 gram of piperacillin
What are some examples of penicillin drug interactions?
- Probenecid can increase the levels of beta-lactams by interfering with renal excretion and this combination is sometimes used intentionally in severe infections to increase antibiotic levels
- Beta-lactams (except nafcillin and dicloxacillin) can enhance the anticoagulant effect of warfarin by inhibiting the production of vitamin K-dependent clotting factors. Nafcillin and dicloxacillin can inhibit the anticoagulant effect of warfarin
- Penicillins can increase the serum concentration of methotrexate; they can decrease the serum concentration of mycopheolate active metabolites due to impaired enterohepatic recirculation
What are the class effects of penicillins?
- All penicillins should be avoided in patients with a beta-lactam allergy (Exception: treatment of syphilis during pregnancy and in HIV patients with poor compliance/follow-up desensitize and treat with penicillin G benzathine
- All penicillins increase the risk of seizures if accumulations occurs
What are some examples of penicillins that can be taken outpatient (oral)?
Pencillin VK, Amoxicillin, Augmentin, Dicloxacillin
What is a note specific to Penicillin VK?
A first-line treatment for strep throat and mild nonpurulent skin infections (no abscess)
What are some notes specific to Amoxicillin?
- First-line treatment for acute otitis media
- Drug of choice for infective endocarditis prophylaxis before dental procedures
- Used in H. pylori treatment
What are some notes specific to Augmentin?
- First line treatment for acute otitis media and for sinus infections (if antibiotics indicated)
- Use the lowest dose of clavulanate to decrease diarrhea
What are some notes specific to Dicloxacillin?
- Covers MSSA only
- No renal dose adjustment needed
What are cephalosporins not active against?
Enterococcus spp. or atypical organisms
Describe the spectrum of activity of first generation cephalosporins
Excellent activity against gram-positive cocci (e.g. Streptococci and Staphylococci) and preferred when a cephalosporin is used for MSSA infections. They have some activity against the gram-negative rods Proteus, E. coli and Klebsiella (PEK), but in general, gram-negative activity is decreased compared to 2nd, 3rd and 4th generation cephalosporins
Describe the spectrum of activity of second generation cephalosporins
Drugs such as cefuroxime cover Staphyloccoci, more resistant strains of S, pneumoniae plus Haemophilus, Neisseria, Proteus, E. coli and Klebsiella. Cefotetan and cefoxitin, have added coverage of gram-negative anaerobes (B. fraqilis)
Describe the spectrum of activity of third generation cephalosporins
- Group 1 includes ceftriaxone, cefotaxime and oral drugs which cover resistant Streptococci (S, pneumoniae and viridans group Streptococci), Staphylococci (MSSA), gram-positive anaerobes (mouth flora) and resistant strains of HNPEK
- Group 2 includes ceftazidime, which lacks gram-positive activity but covers Pseudomonas
Describe the spectrum of activity of fourth-generation cephalosporins
Only includes cefepime, which has broad gram-negative activity (HPNEK, CAPES and Pseudomonas) and gram-positive activity similar to ceftriaxone
Describe the spectrum of activity of fifth generation cephalosporins
Only includes ceftaroline which has gram-negative activity similar to ceftriaxone, but broad gram-positive activity; it is the only beta-lactam that covers MRSA
Describe the spectrum of activity of other cephalosporins
- Beta lactamase inhibitor combinations: ceftazidime/avibactam and ceftolozane/tazobactam have a similar spectrum as ceftazadime but with added activity against MDR Pseudomonas and other MDR gram-negative rods
- Siderophore cephalosporin: cefiderocol uses the iron transport system to enter the gram-negative cell wall. It is approved for complicated UTI/pyelonephritis and active against E. coli, Enterobacter, Klebsiella, Proteus and Pseudomonas
What are the 1st generation cephalosporins?
Cefazolin, Cephalexin, Cefadroxil
What are the 2nd generation cephalosporins?
Cefuroxime, Cefotetan, Cefaclor, Cefotoxin, Cefprozil
What are the 3rd generation group 1 cephalosporins?
Cefdinir, Ceftriaxone, Cefotaxime, Cefditoren, Cefixime, Cefpodoxime, Ceftibuten
What is the 3rd generation group 2 cephalosporin?
Ceftazadime
What is a 4th generation cephalosporin?
Cefepime
What is a 5th generation cephalosporin?
Ceftaroline fosamil
What are the cephalosporin combinations?
Ceftazidime/Avibactam, Cetolozane/Tazobactam
What is a siderophore cephalosporin?
Cefiderocol
What are some contraindications to Ceftriaxone?
- Hyperbilirubinemia neonates (causes biliary sluding, kenicterus)
- Concurrent use with calcium-containing IV products in neonates < 28 days old
What are some warnings associated with cephalosporins?
- Cross sensitivity with PCN allergy (< 10% higher risk with first generation cephalosporins); do not use in patients with type 1 hypersensitivity to PCN (swelling, angioedema, anaphylaxis)
- Cefotetan contains a side chain, which can increase the risk of bleeding and cause a disulfiram-like reaction with alcohol ingestion
- Anaphylaxis/hypersensitivity reactions
- Some drugs can increase INR in patients taking warfarin
What are some side effects of cephalosporins?
Seizures (with accumulation when not correctly dose adjusted in renal dysfunction), GI upset, diarrhea, rash/allergic reactions/anaphylaxis, acute interstitial nephritis, hemolytic anemia (identified with a positive Coombs test), myelosuppression with prolonged use, increased LFTs, drug fever, serious skin reactions (SJS/TEN)
What are some monitoring parameters of cephalosporins?
Renal function, signs of anaphylaxis with first dose, CBC, LFTs
What are some notes about Ceftriaxone?
No renal adjustment, CNS penetration at high doses when meninges inflamed
What is a note about Cefixime?
Cefixime available in a chewable tablet
What is a note about Cefixime/avibactam?
Activity against some carbapenem-resistant Enterobacteriaceae
What is a note about Cefiderocol?
Increase to 2 grams Q6H if CrCl > 120 mL/min
What are some key cephalosporin drug interactions?
- Drugs that decrease stomach acid can decrease the bioavailability of some oral cephalosporins. Cefuroxime, cefpodoxime, cefdinir and cefditoren should be separated by two hours from short-acting antacids, H2Ras and PPIs should be avoided
- Insoluble precipitates may form when ceftriaxone is administered with calcium-containing IV fluids (do not use together in neonates). In adults, IV line should be flushed with a compatible fluid between administration of each product
What are some class effects of cephalosporins?
- Due to a small risk of cross-reactivity, do not choose a cephalosporin on the exam if the patient has a penicillin allergy (exception: pediatric patients with acute otitis media)
- Risk of seizures if accumulation occurs (e.g. failure to dose adjust in renal dysfunction)
What is cephalexin typically used for?
Skin infections (MSSA), strep throat
What is Cefuroxime commonly used for?
Acute otitis media, community-acquired pneumonia (CAP), sinus infection (if antibiotics indicated)
What is cefdinir commonly used for?
CAP, sinus infection (if antibiotics indicated)
What is Cefazolin typically used for?
Surgical prophylaxis
What is Cefotetan and Cefoxitin commonly used for?
- Anaerobic coverage (B. fragilis)
- Common use: surgical prophylaxis (colorectal procedures)
- Cefotetan can cause a disulfiram-like reaction with alcohol ingestion
What is Ceftriaxone and Cefotaxime?
- Common uses: CAP, meningitis, spontaneous bacterial peritonitis, pyelonephritis
- Ceftriaxone: no renal dose adjustment, do not use ceftriaxone in neonates (Age 0-28 days)
What is Ceftazidime and Cefepime active against?
Pseudomonas
What is Ceftolozane/Tazobactam and Ceftazidime/Avibactam active against?
Used for MDR gram-negative organisms (including Pseudomonas)
What is Ceftaroline commonly used for?
CAP, skin and soft tissue infections
What are carbapenems reserved for?
Carbapenems are very broad-spectrum antibiotics that are generally reserved for MDR gram-negative infections. They are active against most gram-positive, gram-negative (includes ESBL-producing bacteria) and anaerobic pathogens. They provide no coverage of atypical pathogens, MRSA, VRE, C. difficile or Stenotrophomonas
How is Ertapenem different from other carbapenems?
Ertapenem is different from other carbapenems as it has no activity against Pseudomonas, Acinetobacter or Enterococcus
What are carbapenem/beta-lactamase inhibitor combinations typically reserved for?
Highly resistant infections (CRE) that are not able to be treated with a single entity carbapenem
What are some examples of carbapenems?
Doripenem, Imipenem/Cilastatin, Meropenem, Ertapenem
What are contraindications of carbapenems?
Anaphylactic reactions to beta-lactam antibiotics
What are some warnings associated with carbapenems?
- Do not use in patients with PCN allergy (small risk of cross-reactivity)
- CNS adverse effects, including states of confusion and seizures
- Doripenem: do not use for the treatment of pneumonia, including healthcare-associated pneumonia (HAP) and ventilator-associated pneumonia (VAP)
What are some side effects associated with carbapenems?
Diarrhea, rash/severe skin reaction (DRESS), seizures with higher doses and in patients with impaired renal function (mainly imipenem), bone marrow suppression with prolonged use, increased LFTs
What are some monitoring parameters of carbapenems?
Renal function, symptoms of anaphylaxis with first dose, CBC, LFTs
What is a note associated with Imipenem?
Imipenem is combined with cilastatin to prevent drug degradation by renal tubular dehydropeptidase
What is Ertapenem commonly used for?
Commonly used for diabetic foot infections
What are some significant carbapenem drug interactions?
- Carbapenems can decrease serum concentrations of valproic acid, leading to a loss of seizure control
- Use with caution in patients with a history of seizure disorder, or in combination with other drugs known to lower the seizure threshold
What are some class effects of carbapenems?
- All active against ESBL-producing organisms and (except Ertapenem) Pseudomonas
- Do not use with penicillin allergy
- Seizure risk (with higher doses, failure to dose adjust in renal dysfunction, or use of imipenem/cilastatin
What are carbapenems commonly used for?
- Polymicrobial infections
- Empiric therapy when resistant organisms suspected
- ESBL-positive infections
- Resistant Pseudomonas or Acinetobacter infections (except ertapenem)
*All are IV only. Ertapenem must be diluted in normal saline
What is the MOA of Aztreonam?
Aztreonam has a mechanism of action similar to beta-lactams; it inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), which prevents the final step of peptidoglycan synthesis in bacterial cell walls
What is Aztreonam reserved for?
Aztreonam covers many gram-negative organisms, including Pseudomonas. It has no gram-positive or anaerobic activity
What are some side effects associated with Aztreonam?
Similar to penicillins, including rash, N/V/D, increased LFTs
What is a note associated with Aztreonam?
Can be used with a penicillin allergy
What is the MOA of aminoglycosides?
Aminoglycosides bind to the ribosome, which interferes with bacterial protein synthesis and results in a defective bacterial cell membrane
What are aminoglycosides active against?
They are active against gram-negative bacteria (including Pseudomonas) and are primarily used as part of an empiric regimen with other antibiotics (general not used as monotherapy)
What are examples of aminoglycosides and its common uses?
- Gentamicin and streptomycin are used for synergy, in combination with a beta-lactam or vancomycin, when treating gram-positive infections. Streptomycin and amikacin are used as second line treatments for Mycobacterial infections
What are the two dosing strategies for aminoglycosides?
- Traditional dosing: uses lower doses more frequently
- Extended interval dosing: uses higher doses less frequently
What is the advantage of extended interval dosing?
There is less accumulation of drug, lower risk of nephrotoxicity and decreased cost