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ID Exam 5 C
Guest Lecture Bacteremia
| Question | Answer |
|---|---|
| Is blood considered a "sterile site" of the body? | YES (should never have bacteria in the blood) |
| Definition of Bacteremia is? | Bacteria in the blood |
| Pathophysiology of Bacteremia: Primary bacteremia is? | Direct inoculation into the blood |
| Pathophysiology of Bacteremia: Secondary bacteremia is? ⭐️ | Originating from FOCAL SOURCE (respiratory, intra-abdominal, skin, etc) ⭐️ |
| Which of the following pts would be considered to have primary bacteremia? A. a pt with S aureus bacteremia and an SSTI. B. A pt with E. coli bacteremia and a UTI C. A pt with S. pneumoniae bacteremia and pneumonia D. A pt with S. epidermis bacteremia and no other s/sx of infection | D. not coming from another source ⭐️ All others deal with OTHER SOURCES |
| Risk factors of Bacteremia (Don't memorize per guest speaker): | Chronic IV access (giving bacteria an entry portal); Implanted hardware/devices/heart valves; Illicit IV drug use; Immunosuppression; Recent surgery; Trauma |
| Management of Bacteremia consists of: | Clinical status--> Blood cultures and Susceptibilities --⭐️ --> Imaging--> source and source control--> Empiric therapy--> Definitive therapy--> Repeat cultures (if necessary)--> Duration of therapy |
| Clinical status in bacteremia includes the SIRS criteria. We need to meet at least 2 of the following: | 1. Temperature >100.4 F or <96.8 F 2. HR >90 bpm 3. RR > 20 bpm 4. WBC count >12 g/L or <4g/L |
| When collecting blood cultures they must be: | 1. Collected before administration of abx (dont want to kill off bacteria and not going to give a true picture of what's actually going on) 2. Collect from two different sites or same site 15 min apart (helps to reduce rates of comtamination) |
| Culture sites can come from: | Peripheral stick; through existing IV lines; Line-tip culture |
| Laboratory reports will tell you the: | gram stain, identify the pathogen and provide susceptibilities |
| Blood cultures can be done via PCR tests which come in 2 types: | 1. BCID/BioFire (43 common bloodstream pathogens; 1 hour for result; Detect resistance genes such as ESBL or carbapenem resistant, etc) 2. Cepheid (S. aureus specific; 1 hour for result; Differentiates b/w MSSA and MRSA) |
| (Don't memorize) Pathogen vs likely contaminants: Which are considered true pathogens in bacteremia? | S. aureus, S. pyogenes, Enterococcus spp., Gram (-) rods, Anaeroboes |
| (Don't memorize) Pathogen vs likely contaminants: Which are considered likely contaminants in bacteremia? | Coagulase- negative staphylococcus, Micrococcus spp., Viridans group streptococci, Diphtheroids |
| Imaging for bacteremia helps locate the source of infection: What imaging can be done? | CT abdomen and pelvis (pyleonephritis; intra-abdominal infections); CT chest/Chest x-ray (Respiratory infections); Echocardiogram (Endocarditis **Key in S. aureus bacteremia) |
| Source considerations for bacteremia can include: | SSTI/DFI?; Any IV lines present? TPN?; Illicit IV drug user?; Recent surgery or trauma?; Symptoms of UTI? Pyelonephritis?; Symptoms of pneumonia? |
| In source control we first want to: ⭐️ | Remove IV lines if possible; If an intra-abdominal source see if we can drain abscess or remove infected organs; Bone infection: amputation |
| In source control we first want to: ⭐️ (cont'd) | In UTI: remove the foley catheter; Respiratory: use abx therapy that penetrates the site of infection; Purulent SSTI: drain abscess |
| To get a CRBSI (Catheter-Related Blood Stream Infection), the organism is growing from: | 2 spots: the catheter tip AND at least 1 peripheral blood culture |
| (Don't memorize) CRBSIs can be prevented via: *Hint: CRBSIs are PREVENTABLE | hand-washing; Full barrier precautions while inserting a CVC, clean skin with chlorohexidine; avoid femoral lines; remove unnecessary lines; Remove lines if NOT places asceptically w/in 48h of placement |
| The main way to prevent a CRBSI and get source control is to? | REMOVE THE IV LINE and treat with abx |
| Abx therapy goals are to: | narrow therapeutic agents, minimize ADRs, Ease of administration, and provide shortest duration |
| Which part of the body do gram (-) bacteria normally live? | GI tract, Urinary tract, etc |
| Empiric tx considerations in gram (-), we look at: | Pt history (suspected source); Microbiologic history (ESBL/resistance history w/in 1 year); Community acquired vs hospital acquired; PsA spp risk factors (Healthcare exposure w/in 90 days, recent abx or chemotherapy tx w/in 90 days; Immunocompromised; HD |
| Could you step-down from IV to PO therapy in gram (-) bacteremia? | YES |
| FYI: IV to PO for gram (-) bacteremia: may consider if: | rapid clinical improvement; uncomplicated bacteremia (E. coli, Proteus mirabilis, Klebsiella pneumoniae) |
| FYI: IV to PO for gram (-) bacteremia: preferred agents are: | Urinary source: amox (w/ or w/o) clavulanate or Cephalexin Non-urinary source: Cipro/Levo OR TMP-SMX |
| Gram (-) Bacteremia summary: Empiric therapy selection based on: | Previous pathogens; risk for drug-resistant pathogens; Antibiogram data |
| Gram (-) Bacteremia summary: Moving from Empiric therapy selection to Definitive Therapy is based on: | Pathogen susceptibilities; Narrow agents preferred; Consider IV to PO switch in appropriate patients |
| Gram (-) culprits could include? | Klebsiella spp., Proteus spp., PsA spp., E. coli, Serratia spp., Morganella spp., ESBL |
| Gram (+) culprits in bacteremia could include: | Skin flora: Staph aureus, Strep species; GI flora: Enterococcus species |
| Empiric tx considerations in gram (+), we look at: | Pt history (suspected source); Microbiologic history (VRE/MRSA history in the previous year); Community-acquired vs hospital acquired; MRSA risk factors (hospitalizations and tx w/ IV abx in the last 90 days; nursing home; Hemodialysis dependent) |
| Empiric therapy for S. Aureus: MRSA? | Dapto, Vanco, Linezolid |
| Empiric therapy for S. Aureus: MSSA? | Cefazolin, Anti-staphylococcal PCN |
| My pt is already on Vanco and is growing MSSA. Do I NEED to de-escalate? Do we use Vancomycin for MSSA? ⭐️ | using for MSSA bacteremia is associated with a higher mortality rate when compared to cefazolin or the anti-staphylococcal PCN ⭐️ |
| When pt has Staphylococcus aureus bacteremia we? | Consult ID specialist ⭐️ |
| When pt has Staphylococcus aureus bacteremia we order a? | Echocardiogram (preferably a TTE) TTE>>>> TEE (This is used to rule out endocarditis) |
| Where do we normally find S. Aureus? | Skin |
| Streptococcus Species Empiric tx for S. Pneumoniae: | IV ceftriaxone; Notes: (common CNS/CAP pathogen) |
| Streptococcus Species Empiric tx for S. Pyogenes: | IV PCN + IV Clindamycin or Linezolid Notes: Toxin producing organism (can d/c Clinda or linezolid in 48h if shock, organ failure, or necrtoizing fasciitis are absent) |
| Streptococcus Species Empiric tx for All other Streptococcus spceies: | IV Beta-lactams Notes: Very PCN-susceptible |
| Where are Streptococcus species normally found? | Skin |
| Enterococcus Species: E. Faecalis is highly ________ and _________ -susceptible | ampicillin; Vancomycin |
| Enterococcus Species: E. Faecium is less ___________ to ampicillin and vanco. Faecium = _______/_________ resistant | Mean/More resistant than E. faecalis |
| Which abx can we NOT use for Enterococcus Bacteremia? | Cephalosporins can never be used (won't work) |
| Tx options for Enterococcus Faecalis includes? | IV ampicillin or IV vanco (if ampicillin allergy) |
| Tx options for Enterococcus Faecium includes? | IV Dapto 8-12 mg/kg OR Linezolid |
| Where do we normally find Enterococcus? | GI tract |
| Can you step-down from IV to PO therapy in gram (+) bacteremia? | NO |
| Gram (+) Bacteremia Tx summary: Staph aureus: | MRSA: Dapto, vanco, linezolid; MSSA: cefazolin, oxacillin, or nafcillin; ID consult and rule out endocarditis w/ TTE echocardiogram; |
| Gram (+) Bacteremia Tx summary: Streptococcus speices: | IV PCN or Ceftriaxone |
| Gram (+) Bacteremia Tx summary: Enterococcus species: | E. Faecalis--> Ampicillin E. Faecium--> Dapto or Linezolid |
| When do we repeat blood cultures with gram (-) organisms? ⭐️ | Not routinely recommended unless clinical suspicion of persistent infection |
| When do we repeat blood cultures with gram (+) organisms? ⭐️ | Every 24-48h until blood is sterilized; Remember DAY 1 of therapy = first negative blood culture |
| In terms of duration of therapy in bacteremia, in uncomplicated we see _______ durations, whereas in complicated we see _______ durations | shorter; longer |
| In gram (-) durations: uncomplicated is for (1)?; complicated is for (2) | 1. 7 days 2. 14 days |
| Uncomplicated gram (-) bacteremia means your meeting at least 1 of the following criteria? *if your are not meeting ANY of these criteria, you are COMPLICATED because you would be secondary to the following sources: | Urinary tract; GI/biliary tract; Catheter-related; Pneumonia; SSTI |
| Uncomplicated gram (+) bacteremia means you must meet all of the following (i.e in staph aureus): | Sterile repeat cultures w/in 48-96h; Deferevescence (no fever) w/in 72h; Exclusion of infective endocarditis; Abscence of implanted devices (i.e heart valve, orthopedic hardware); non-hemodialysis dependent |
| ⭐️ In gram (+) staph aureus duration: uncomplicated is for (1)? complicated is for (2) | 1. 2 weeks 2. 4-6 weeks |
| In gram (+) Streptococcus species duration would be for? | 14 days |
| In gram (+) Enterococcus species duration would be for? | 7-14 days |
| Definition of Infective Endocarditis is? | Infection internal heart inflammation |
| Risk factors for Infective Endocarditis includes? | Advanced age; Previous hx of endocarditis; Presence of prosthetic valve or implanted cardiac device; Congenital heart disease; Illicit IV drug use; Chronic IV access; Poor dentition/oral hygiene |
| Prevention (consider in high-risk pts undergoing bacteremia-inducing procedures) high risk pts include? | prosthetic material in the heart (i.e valves); history of endocarditis; history of heart transplant; Congenital heart disease |
| Prevention (consider in high-risk pts undergoing bacteremia-inducing procedures) bacteremia-inducing procedures include: | Dental procedures w/ perforation of oral mucosa; invasive respiratory procedures; invasive procedures involving skin or musculoskeletal tissues |
| When a pt gets a dental procedure--> perforation of oral mucosa (dental proceudure)--> infiltration to the bloodstream (bacteremia--> leading to bacteria sticking to heart valve (_______ _________) | Infective endocarditis |
| (Test Question) Dental prophylaxis includes: 1 dose 30-60 min prior to a dental procedure. What is first line? Second Line? | 1st line (Amoxicillin) 2nd line: Azithromycin/Doxycycline |
| What bacteria do we suspect with an infective Endocarditis? | Staphylococcus aureus; Viridans Streptococci; Strepotococcus bovis; HACEK* group; Enterococcus species |
| What imaging is used to detect endocarditis? | TTE (Trans-thoracic echocardiogram); TEE (Trans-esophageal echocardiogram is more invasive) |
| Tx Principles for Infective Endocarditis includes: | pathogen; Native vs prosthetic valve; susceptibility; dosing; duration (from first NEGATIVE blood culture) |
| Monitoring for Infective Endocarditis includes? | -Clinical improvement (Defervescence; resolution of leukocytosis) -Blood culture (every 24-48h until negative -Repeat TTE/TEE after completion of antimicrobial therapy |
| Endocarditis summary: Dental prophylaxis in high-risk pts: first and second line agents: | (Amoxicillin first line; Doxycycline or azithromycin second line |
| Endocarditis summary: Common pathogen--> | Staphylococcus aureus is VERY common |
| Endocarditis summary: Imaging of valves (TTE--> TEE) | (TTE--> TEE) |
| Endocarditis summary: For treatment considerations: It's determined by pathogen, look at: | native vs prosthetic valve, susceptibility; Long duration |
Created by:
Xander635
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