ID

Define: Minimum inhibitory concentration

The minimum concentration of an antibiotic that inhibits growth of an organism for 24 hours.

What is a broad spectrum antibiotic? Narrow spectrum?

Broad = affects both GP and GN organisms. Narrow spectrum = only GP or GN, not both.

What is the DOC for streptococcus?

Penicillin family

What kind of bacteria is strep. Pygogenes?

GP, coccus, common pathogen for "strep throat" and cellulitis.

What is group B strep?

Strep. Agalactiae. GP. Normal flora of the vagina - not an issue for the patient, but can be for the baby. Common pathogen of neonatal infections.

How do we manage a Group B Strep (GBS) positive female patient who is giving birth?

a few weeks prior to delivery, swab to determine if patient is GBS positive or negative (whether she is colonized by this bacteria: streptococcus agalactiae). If GBS(+), then 24 hours prior to delivery, we give the mom IV ampicillin to prevent neonatal infections (neonatal meningitis/sepsis).

What is Pneumococcus?

Streptococcus pneumoniae. GP organism. Again, DOC for streptotoccus group is something from the penicillin family. This pathogen is the number 1 cause of many infections above the diaphragm: otitis media, sinusitis, pneumonia, meningitis.

What is strep. Viridans?

A bacterial part of the normal flora of the mouth/GI. We worry about dental infections, and possible endocarditis in patients that are high risk.

What kind of infections are caused by enterococcus?

Enterococcus is another GP bacteria, found in the GI tract. Causes many infections, especially those that are nosocomial.

What kind of resistance do we see with enterococcus?

VRE (vanco resistance)

What drugs can we use to treat VRE?

daptomycin, synercid, linezolid, tigecycline.

What drugs do we use to treat MSSA?

staphylococcus abx - dicloxacillin, nafcillin, oxacillin.

What lab exam/test can we use to differentiate between GP organisms?

if COAG-positive, then its staphylococcus.

What is the causative pathogen for impetigo?

superficial skin infection, typically found on children. Caused by staph. Aureus. Treatment: mupirocin ointment TID x 3-5 days, or retapamulin (Altebax). If Severe, may need systemic antibiotics.

How do we eradicate MRSA colonized on a patient?

use Bactroban nasal or hibiclens soap; because MRSA lives in the nares. Typically only indicated for patients who have recurrent staph infections.

What are the PO options for treating MRSA?

Bactrim, Doxycycline, Clindamycin, Linezolid, Rifampin (only as adjunct, never monotherapy).

What are the IV options for treating MRSA?

Vanco, Daptomycin, Linezolid, Tigecycline, Synercid, Clindamycin, Ceftaroline, Telavancin, Dalbavancin, Oritavancin.

What is cornebacterima diptheriae?

GP rod. Forms a "pseudomembrane" over the tonsils that is gray in color (unlike your typical white/yellow for strep). We do have a vaccine for this, which is why it's not seen very often anymore (diphtheria).

How do we treat cornyebacterium diptheriae infection in patients?

this bacteria produces a toxin which damages tissue. Treatment requires anti-toxin + antibiotic = PCN or erythromycin x 14 days.

How do we treat patients who have had contact with those infected with cornyebacterium diphtheriae?

they should get the vaccine if they haven't gotten it before; get the booster if they have received the diphtheria vaccine. And then ABX (PCN IM x 1 dose or erythromycin for 7 days) (instead of the 14 days required for treatment). This is prevention!

What is listeriosis?

a foodborne illness - a GP rod. Causes GI issues, but can also translocate to the blood causing sepsis and meningitis. Also a concern for newborns.

What are the common causes of neonatal meningitis?

GBS (strep. Agalactiae), Listeria monocytogenes, and e. coli.

How do we treat listeria?

Ampicillin & Gentamicin.

What is bacillus anthracis?

GP rod.

What are the 2 main bacteria in the GN cocci group?

Neisseria and Moraxella catarrhalis.

What is "meningococcus?"

Neisseria - a gram negative cocci.

How do we treat meningitis?

Start empiric treatment with Ceftriaxone + Vanco. Get cultures (from a spinal tap/lumbar puncture). Once cultures show menigicoccus, de-escalate to penicillin G or ampicillin (may continue ceftriaxone).

What is the treatment for Neisseria gonorrhea?

Ceftriaxone 250 mg IM x 1 PLUS azithro 1gm po x 1 (preferred) or doxycycline 100 mg po BID x 7 days.

In treating Neisseria gonorrhea, how do we treat if a patient is allergic to PCNs?

give azithromycin 2gm + gentamicin 240mg IM

What is Moraxella Catarrhalis?

Normal flora of the respiratory tract. This is a GN cocci. Common cause of otitis media and sinusitis.

What are the common causative pathogens for otitis media?

strep pneumoniae (Pneumococcus), H. Influenzae, Moraxella Catarrhalis

What is the most common cause of UTIs?

E. coli

What are the antibiotics that have activity against pseudomonas?

Pip/tazo, ceftazidime, cefepime, carbapenems except ertapenem, ciprofloxacin and levofloxaxin, aztreonam.

What is the duration of treatment for pyelonephritis?

10 days.

What is the duration of treatment for a simple UTI?

3 days

What is the duration of treatment for acute cystitis?

3-7 days

What is the treatment duration of prostatisis?

28 days

Can avelox be used to treat a UTI?

no. Avelox goes through the liver, it does not concentrate in the urine - ineffective for UTIs.

What is the treatment regimen for H. Pylori?

usually triple or quadruple therapy. Traditional: amoxicillin 1000 mg BID, Clarithromycin 500 mg BI, + PPI once daily, for 14 days. If pt is allergic to PCNs, give metronidazole 500 mg BID.

What is the treatment for meningitis due to haemophilus influenzae?

Ceftriaxone. Can also use cefotaxime and ampicillin as alternatives.

Which pathogens require treatment if patients don't have the infection, but have come into close contact with other patients who have?

(1) Cornyebacterium diphtheriae. (2) Neisseria meningitidis (meningococcus), (3) haemphilus influenzae

What is the post-exposure prophgylaxis we give to patients with close contacts to h. influenzae?

Rifampin 600 mg daily x 4 days, or cipro 500 mg single dose, or ceftriaxone IM x 1 dose.

What infection does pertussis cause?

Whooping cough.

What is the drug of choice for whooping cough?

Macrolides. This does not reduce duration of symptoms (which can last 3 months) but reduces the chance of transmission.

What is the DOC of bacteroides fragilis?

metronidazole. This organism is a gram negative rod, ANAEROBE. Commonly causes intra-abdominal infections.

What kind of fungal infection is tineas capitis?

on the scalp. Requires PO Griseofulvin x 4 wks

Tineas versicolor is found where? Treatment?

chest and abdomen. Use OTC antifungals.

Tineas corporis? Cruris? Pedis? Treatment?

cruris = jock itch. Pedis = athletes foot. Corporis = ringworm. Treat with OTC antifungals.

What is onychomycosis? What is the duration of treatment?

nail fungus. Toe = 12 weeks. Fingers = 6 weeks. If there is no lunar involvement, can use topical formulations. If lunar involvement, then must treat with systemic antifungals. Terbinafine and itraconazole can be used - monitor LFTs.

Which fungus is the major cause of meningitis in AIDS patients?

Cryptococcus neoformans.

Which fungus causes valley fever?

Coccidiomycosis. Treat with itraconazole or fluconazole.

What is the treatment for herpes simplex virus?

acyclovir, famciclovir, valacyclovir.

What is RSV?

respiratory Synctial Virus. Common cause of bronchiolitis/pneumonia in infants. Treatment: Synagis for prophylaxis, give to children at risk during high risk season.

When we do give prophylaxis in HIV against cytomegalovirus?

CMV - infections occur when CD4 < 50.

How do we treat chlamydia?

azithromycin 1gm po x 1 - OR - doxycycline 100 mg BID x 7 days

How do we treat gonorrhea?

Ceftriaxone 250 mg IM x 1 dose. If pcn allergy, can give 2gm of azithromycin.

What causes atypical pneumonia?

Mycoplasma pneumoniae. Treatment - give macrolides or tetracyclines. If resistant, give FQs. Mycoplasma is an atypical bacteria (has no cell wall, so beta-lactams will not work). This is why we give macrolides (zpak).

What is the DOC for syphilis?

PCN. Doxycycline or CTX if PCN allergy.

What does borrelia burgdorferi cause?

this bacteria is a spirochete. It causes Lyme disease, carried by infected deer ticks. Typically in forested or woody areas. Lyme disease looks a lot like the flu, but they develop a "bulls-eye rash" termed erythema migrans.

How do we treat lyme disease?

Early: po doxycycline or Amoxil or cefuroxime (Ceftin) x 14 days. Late: treat for 28 days. We try to treat ASAP because if disease progresses, we can get other organs affected - cardiac or neurologic. With this involvement, treat for 28 days.

A patient presents with flu-like symptoms and a bull's eye rash. Had also recently been camping in the forest. What is this?

Lyme disease, due to borrelia burgdorferi.

How do we prevent lyme disease?

lifestyle mods (long sleeves, light colored clothes so ticks can be spotted, use insect reellant (DEET) or insecticide (permethrin), avoid tall grass, etc. Pharmcologic intervention - only needed if confirmed tick bite: doxycycline 200 mg po x 1 dose in patients age > 8 yo.

What are the most common pathogens of endocarditis?

staph (#1), strep (#2), and enterococcus. May also be caused by pseudomonas and candida albicans.

What is infective endocarditis?

infection of the heart valves.

What is the empiric therapy for infective endocarditis?

Vanco IV; when cultures/susceptibilities return, then we can de-escalate. Treat IV for 2-8 weeks.

What patients require endocarditis dental prophylaxis?

usually patients with structural heart defects/interventions in the past: prosthetic heart valves, previous hx of endocarditis, cardiac transplant patients with valvulopathy, congenital heart disease (first 6 months after CHD repair with prosthetics) or cyanotic CHD.

Which of the following requires endocarditis dental prophylaxis? A) Prosthetic heart valves. B) history of endocarditis. C) cardiac transplant with valvulopathy. D) Cyanotic CHD. E) CHD, first 6 months after repair with prosthetics. F) Mitral valve prolapse.

All of the above EXCEPT for F) mitral valve prolapse.

What are the common bacterial pathogens that cause meningitis?

(1) strep. Pneumoniae, (2) Neisseria meningitidis, (3) h. influenzae, (4) GBS for neonatal meningitis, (5) listeria (elderly)

What are the common bacterial pathogens that cause upper respiratory infections? (otitis media, sinusitis, pharyngitis)

(1) s. pyogenes (GAS; strep throat). (2) strep. Pneumoniae. (3) h. influenzae. (4) Moraxella catarrhalis.

What are the common bacterial pathogens that cause lower respiratory, community-acquired infections?

(1) strep. Pneumoniae. (2) h. influenzae. (3) atypicals: legionella, mycoplasma (walking pneumonia, why we need zpak in aduts)

What are the common bacterial pathogens that cause endocarditis?

staph, strep, and enterococcus species.

What are the common bacterial pathogens that cause intra-abdominal infections?

enteric GN rods, enterococci, streptotocci, bacteroides species.

What are the common bacterial pathogens that cause lower respiratory infections, hospital acquired?

Staph. Aureus, pseudomonas, enteric GN rods, strep. Pneumoniae.

What are the common bacterial pathogens that cause UTIs?

E. coli, proteus, klebsiella, staph. Saprophyticus, enterococci, streptococci

What are the common bacterial pathogens that cause skin/soft tissue infections?

(1) staph. Aureus, (2) strep pyogenes, (3) staph. Epidermidis, (4) Pasteurella multocida, (5) GN rods if pts are diabetic.

What are the common bacterial pathogens that cause bone and joint infections?

(1) staph aureus. (2) staph epidermidis. (3) streptococci. (4) Neisseria gonorrhea. (5) sometimes GN rods, but only in specific situations

How do we monitor a treatment response when giving abx for an infection?

Fever, WBC trend, reduction in signs/symptoms of infection. May look at CXR, negative cultures, pain/inflammation.

What are some reasons antibiotic therapy may not be working?

(1) antibiotic factors: wrong spectrum, inadequate dose, poor tissue penetration, drug-drug interactions, non-adherence, inadequate duration of therapy. (2) pathogen factors: resistance, super infection, alternative etiology (viral, fungal, noninfectious cause). (3) host factors: uncontrolled source of infection (abscess somewhere…?), immunocompromised.

What drug would we use for surgical prophylaxis?

Cefazolin

What are the classic signs/symptoms of meningitis?

Severe headache, stiff neck, altered mental status.

What re the most common pathogens for meningitis?

strep pneumo, Neisseria meningitidis (meningococcus), H. influenzae, and listeria.

What is the treatment regimen for adults with community acquired meningitis?

Ceftriaxone or Cefotaxime 2gm IV q12 PLUS vanco 30-45/mg/kg/day. Duration of treatment depends on the causative pathogen (treat from 7-21 days)

An adult presents with severe headache, stiff neck, and altered mental status. He also has a PCN allergy.

Patient likely has meningitis. Common pathogens: strep pneumo, Neisseria meningitidis, h. influenzae or listeria. Treat with FQ + vanco - duration depends on pathogen, treat for 7-21 days.

Bulging tympanic membrane, otorrhea, otalgia - what kind of infection may this indicate? Pathogens?

Otitis media. Pathogens: strep. Pneumoniae, h. influenzae, Moraxella catarrhalis.

How do we treat otitis media?

depends on severity, and depends on the child's age. If it's not severe - watch and wait 48-72 hours - these things may resolve on their own. If child is younger than 2, you may consider abx at any time. If it's bilateral (even without otorrhea), start abx. For a child older than 2, we may consider watchful waiting if AOM is bilateral, but no otorrhea. Definitely start if severe symptoms arise.

What signs/symptoms makes an acute otitis media infection "severe."

Otalgia > 48 hrs, T > 39C in past 48 hours.

What is the first line drug therapy for otitis media?

Amoxil 80-90 mg/kg/day in 2 divided doses, or augmentin 90mg/kg/day in 2 divided doses. alternative - give cefdinir 14mg/kg/day in 1 or 2 doses. Treatment duration depends on age, but generally 5-10 days. If < 2yrs, then 10 days. > 6yrs = 5-7 days.

Is there a vaccine available to prevent acute otitis media?

Prevnar 13 - recommended for all children. (this covers strep. Pneumo, or pneumococcal).

What is the treatment for pharyngitis?

Strep throat, caused by strep. Pyogenes. There is a rapid antigen test used to diagnose. If positive, DOC is penicillin. Can also use Amoxil, cephalosporins. If beta-lactam allergy then clarithro, azithro, or clinda. Treat for 10 days (unless using a Zpak, then 5 days)

When is sinusitis indicated for treatment with antibiotics?

symptoms lasting > 10 days, severe symptoms (fever > 102, face pain, purulent nasal discharge) > 3 days, or worsening of symptoms.

What is the treatment recommendation for sinusitis?

common pathogens: strep. Pneumoniae, h. influenzae, Moraxella catarrhalis. First line: augmentin (adults 5-7 days, kids 10-14 days). Alt: cephalosporins + clinda, or doxycycline. Or respiratory quinolone (all except cipro)

In COPD exacerbation, when do we treat? How do we treat?

abx indicated with presence of 3 cardinal symptoms: increase in dyspnea, sputum volume, and sputum purulence. OR, if ventilation is required. Treatment: augmentin x 5-10 days. Alt: azithro, doxy.

What are the common pathogens for CAP?

step. Pneumoniae, h. influenzae, mycoplasma pneumoniae.

When treating CAP in the outpatient setting, how do we determine what medication to use?

(1) check for history of abx use in the past 3 months. (2) look for comorbidities (chronic heart disease, lung, liver, renal, diabetes, etc) or immunosuppression. (3) if the first 2 questions are positive, patient belongs in "category 2," if otherwise healthy, then category "1." (4) choose an abx based on category - these categories look for comorbidities and possible abx resistance. If CATEGORY 1: macrolide or doxycycline. If CATEGORY 2: beta-lactam + macrolide/doxycycline, or respiratory FQ.

What beta-lactams are typically used for CAP in patients with abx history in last 3 months?

high dose Amoxil, augmentin, cefidinir, cefpodoxime. Must be added to macrolide or doxycycline if pt falls in category 2.

RP is a 46 yo female who presents to the urgent care clinic with SOB, productive cough, and temperature of 100.2. CXR reveals lower lung infiltrate. PMH include back pain and schizophrenia. Medications: Geodon 40 mg BID and trazodone 50 mg qhs. Which empiric antibiotic therapy should she get for pneumonia?

pt has no recent abx use, no comorbidities, and is not immunosuppressed. Options include macrolide or doxycycline. Macrolides can prolong QT interval, as can trazodone and Geodon. Doxycyline is the best choice.

How do we treat CAP patients that require inpatient management?

beta-lactam + macrolide/doxycycline. Beta-lactams preferred - ceftriaxone or cefotaxime, plus azithromycin. OR, we can use respiratory FQ as monotherapy. Duration typically 5-7 days.

What is hospital-acquired pneumonia? VAP? Why is this different from CAP?

HAP has an onset > 48 hours after hospital admission - meaning, these patients picked up something during their hospital stay - risk of nosocomial pathogens. VAP occurs > 48 hours after the start of mechanical ventilation. In these patients, we worry about infection with MRSA or pseudomonas.

In HAP/VAP, what are the risk factors for MRSA, MDR pseudomonas, or other pathogens?

IV abx use within 90 days, high prevalence of MRSA in the unit, positive MRSA screen.

What are the risk factors for MDR pathogens in VAP?

hospitalization for at least 5 days prior to VAP, septic shock at time of VAP, ARDS preceding VAP, hemodialysis prior to VAP.