Infectious Disease II - Bacterial Infections Flashcards
Name common pathogens in bone and joint infections.
s. aureus, s. epi, strep, n. gono
Name common pathogens in UTIs.
E. coli, kleb, proteus, strep, enterococci, s. saprophyticus
Name common lower respiratory pathogens (community and hospital).
community: atypicals, strep pneumo, h. flu, possibly enteric GNRs
hospital: pseudomonas, enteric GNR, s. aureus, strep pneumo
Name common meningitis pathogens.
Listeria (in very young and elderly), neisseria, GBS (young), E. coli (young), s. pneumo, h. flu
Name common upper respiratory pathogens.
s. pneumo/pyo, h. flu, moraxella
Name common endocarditis pathogens.
s. aureus, s. epi, strep, enterococci
Name common intra-abdominal pathogens.
enteric GNR, enterococci, strep, bacteroides
Name common SSTI pathogens.
staph, strep, GNR (diabetics)
How long before surgery should preop abx be hung?
Most antibiotics should be hung 1 hour before surgery, except FQs and vanc, which should be 2 hours before.
Which types of operations require additional coverage outside of skin flora? What additional bugs should be considered?
colorectal procedures and hysterectomies require anaerobic and GNR coverage
Which antibiotics are most frequently used in preop ppxs?
For routine procedures that don’t warrant additional pathogen coverage, cefazolin, cefuroxime, and vanc are the most common choices. For anaerobic/GNR coverage, cefotetan, metronidazole, amp/sulb, cefoxitin, ertapenem, and ceftriaxone are options.
What are the drugs and doses used for meningitis empirically in most patients (2-50 years old)?
To cover neisseria and strep pneumo, high doses of vanc and ceftriaxone are used.
30-45 mg/kg/day vanc and 2g q12h ceftriaxone
Which medication is used to cover for Listeria?
ampicillin
What is the empiric meningitis regimen for adults aged >50 years?
ceftriaxone, vanc, and ampicillin covering strep, neisseria, listeria, and GNB
What is the empiric meningitis regimen for neonates?
ampicillin with cefotaxime or gent
What are the preferred drugs and doses for acute otitis media treatment? How long should you treat?
amoxicillin 90 mg/kg/day or augmentin 90 mg/kg/day
use the lowest amount of clavulanate possible to avoid diarrhea SE
Tx duration is usually 5-7 days for mild/moderate infections, and 10 days for severe.
When would it be a good idea to use augmentin over amoxicillin in a child presenting with AOM?
if the child has had amoxicillin in the last 30 days
What are the criteria for anti-infectives in suspected pharyngitis? sinusitis?
pharyngitis - positive rapid antigen test
sinusitis - either 10 days of symptoms or 3 days of severe symptoms
What are first-line treatments for pharyngitis and sinusitis in patients that meet anti-infective criteria?
pharyngitis - penicillin or 1/2 gen ceph
sinusitis - augmentin, if tx failure or severe pen allergy cna use clinda, resp FQ, or doxy
How long should you treat pharyngitis? sinusitis?
pharyngitis is treated for 10 days unless using azith (5d)
sinusitis initial tx is 5-7 days, may require 7-10 if treatment failure
How is acute bronchitis not related to a COPD exacerbation treated?
NOT with antibiotics, as the cause is often not bacterial. ONLY consider antibiotics in severe cases. Supportive care (hydration, antipyretics, antitussives) recommended.
When are antibiotics warranted in acute bronchitis?
1) when related to COPD exacerbation and meets specific criteria (another question)
2) when pneumonia is suspected
3) when whooping cough (Bordatella) is confirmed
What are the criteria for antibiotic use in acute bacterial exacerbations of chronic bronchitis?
increased sputum purulence plus either increased sputum production or increased dyspnea
In a health patient with no recent antibiotic use, name two drugs most commonly used to treat outpatient CAP.
1) azithromycin
2) doxycycline
What characteristics should you look for in a patient history that would suggest combination or broader spectrum monotherapy would be necessary for outpatient CAP?
1) comorbidities like CHF, DM, liver/renal disease, malignancy, asplenia
2) recent antibiotic use (last 90 days)
3) immunocompromised
What agents should be used in patients the require more extensive treatment for outpatient CAP?
1) beta-lactam and macrolide
2) resp FQ monotherapy
3) beta-lactam and doxy
What are the preferred beta-lactams in outpatient CAP?
high dose amoxicillin (1g TID), cefpodoxime, augmentin, cefdinir
What are the preferred beta-lactams for inpatient CAP?
ceftriaxone, cefotaxime
When should a resp FQ be used in inpatient CAP?
Due to safety concerns, FQs should be reserved for patients with severe penicillin allergies.
What are some risk factors for MDR pathogens and MRSA in patients with HAP/VAP?
1) IV abx use within the last 90 days
2) high prevalence of MRSA in hospital unit
3) hospitalization of at least 5 days prior to ventilation
4) septic shock at the time of VAP onset
5) acute RRT at time of VAP onset
When is double coverage of pseudomonas warranted?
Use two drugs that cover pseudomonas when the patient has a high risk of mortality, has had IV abx in the last 90 days, or has MDR risk factors for HAP/VAP.
Which drugs will cover pseudomonas and MSSA in patients without risk factors for MDR or MRSA?
cefepime, levo, pip/tazo, meropenem
This class of drugs will only be used for pseudomonas as combination therapy - they are not options for single coverage of pseudomonas.
aminoglycosides
If a patient has risk factors for MRSA, they will have one of these two drugs on board:
vanc or linezolid
What are the 6 pseudomonas monotherapy options?
cefepime, ceftazidime, aztreonam, levofloxacin, pip/tazo, meropenem
What is the general duration of treatment for HAP/VAP?
7 days, longer or shorter based on radiologic/lab/clinical findings
two most important rifampin pearls/counseling points
1) take on an empty stomach - food decreases absorption
2) will cause bodily secretions to be stained orange, which can stain contact lenses, clothes, etc.
Which drug may be substituted for rifampin in patients that must avoid drug interactions?
rifabutin (dosed at half rifampin dose - 5 mg/kg/day)
Which drugs are part of the induction regimen for TB?
rifampin 10 mg/kg daily, isoniazid, 5 mg/kg daily, pyrazinamide 25 mg/kg daily, and ethambutol 20 mg/kg daily
Describe the treatment approach for TB.
Induction and continuation phases. induction is usually 2 months, and continuation is usually 4 but may be prolonged. the most common reason to prolong the continuation phase to 7 months is a positive sputum culture at the end of the induction phase. higher doses of continuation drugs may be given less frequently (2-3x/week) and directly observed if adherence is an issue.
two most important pearls/counseling points for isoniazid
1) take on empty stomach
2) warning for peripheral neuropathy - supplementation with pyrodoxine 25 mg daily can help prevent
What is a side effect common to all TB drugs that must be monitored for?
liver wreckage
adverse effects of isoniazid
1) hyperglycemia
2) GI upset
3) hemolytic anemia
4) drug induced lupus erythematosus
adverse effects of pyrazinamide
1) hyperuricemia
2) GI upset
3) rash
4) arthralgia/myalgia
adverse effects of ethambutol
1) optic neuritis - contraindicated if previously existing
2) confusion/hallucinations
Which two TB drugs must be given with a longer dosing interval in renal impairment?
pyrazinamide (CrCl < 30) and ethambutol (CrCl < 50)
most common causative organisms in endocarditis
staph, strep, enterococci, viridans strep
What patient anatomical characteristics guide endocarditis treatment?
The duration is mainly driven by the level of resistance of the organism and the valve type (tissue vs. prosthetic). Antibiotic choice is determined by organism and susceptibility.
What is the recommended duration of therapy for aminoglycosides when used for synergy?
2 weeks
Give the most common endocarditis prophylaxis regimen for all patients and options for penicillin allergic patients.
amoxicillin 2g one hour before procedure
clindamycin 600 mg or azithromycin 500 mg for penicillin allergy
Describe the difference between primary and secondary peritonitis.
Primary peritonitis is most frequently caused by liver disease. Secondary peritonitis usually follows abdominal trauma (ulceration, ischemia, surgery).
What are the most common causative organisms in intra-abdominal infections?
anaerobes, strep, and enteric gram negs
note: anaerobes much less common in primary than secondary peritonitis
What is the usual treatment duration for intra-abdominal infections?
4-7 days, longer if more severe or abscesses are present
What additional organisms should you cover for in critically ill patients with intra-abdominal infections?
pseudomonas, CAPES
What are the most common agents used for typical, non critically ill patients with intra-abdominal infections?
cefoxitin (not enterococci), moxi (moderate activity for enterococci), ertapenem, cephalosporin/FQ + metronidazole
What are the 3 most common SSTIs and the treatments of choice for each?
1) impetigo (staph and strep) - treated with topical mupirocin or systemic Keflex if numerous widespread lesions
2) folliculitis and related (staph including MRSA) - Keflex for MSSA, Bactrim or doxy if suspect CA-MRSA
3) cellulitis (staph, strep) - Keflex or penicillin if mild, bactrim or doxy of suspect CA-MRSA
For how long should you treat a diabetic foot infection?
usually 7-14 days, weeks if deeper infection present such as osteo
Which patients would meet criteria for an uncomplicated UTI?
nonpregnant premenopausal female patients with no urologic abnormalities
Which patients would be classified as a complicated UTI?
all males with UTI, pregnant females, catheter-related UTIs
two most common treatments for uncomplicated UTIs
1) macrobid 100 BID WITH FOOD
2) Bactrim DS BID if CrCl 30-60
most common pathogens for UTI
E. Coli, E. Coli, E. Coli, Klebsiella, Proteus, enterococci
Which drug class is preferred for pyelonephritis or complicated UTIs?
FQs (except moxi)
If quinolone resistance is more than 10%, give a single dose of ceftriaxone or extended interval AG followed by quinolone. can also use bactrim or a beta-lactam for 14 days
In which group of patients will asymptomatic bacteruria always be treated? What is the UA cutoff of bacteria/mL?
Bacteruria is defined as at least 10^5 bacteria/mL on a UA. Treat all cases in pregnant women, as lack of treatment can be harmful to the fetus.
preferred tx for asymptomatic bacteruria in pregnant women
augmentin or oral cephalosporin
What are the ACOG recommendations for pregnant patients with penicillin allergies that get a UTI?
nitrofurantoin and bactrim have recommendations per ACOG, but have limited use. Both should be avoided in the 1st and 3rd trimesters.
How long should asymptomatic bacteruria be treated in pregnant women?
3-7 days
What are the two recommended treatment options for C. diff initial episode?
vanc 125mg PO QID or fidaxomycin 200 mg BID
both are 10 days duration
In recurrent C. diff, what are the treatment options if vancomycin was used initially? fidaxomycin? metronidazole?
vanc - fidaxomycin 200 mg BID or vanc tapered/pulsed regimen
fidax - vanc tapered/pulsed regimen
metro - vanc 125 mg QID
What regimens are available for patients that present with fulminant or complicated C. diff infections?
vanc 500 mg QID or metronidazole 500 mg IV TID
State the preferred treatments for each stage of syphilis (primary/early, secondary, tertiary/late).
primary and secondary have very similar recommendations - IM benzathine penicillin 2.4 million U x1 dose for primary and weekly x3 doses for secondary
