23. Antibiotics in Cardiorespiratory Infections Flashcards
What infections affect the upper respiratory tract (URT)?
What infections affect the lower respiratory tract (LRT)?
What are 3 common categories of organisms of the URT?
Sinusitis, tonsilitis, pharyngitis, laryngitis, rhinitis. Otitis media (acute).
Tracheitis, bronchitis, bronchiolitis, pneumonia, pleurisy (pleura inflammation often caused by infection).
1) Normal flora (e.g. viridans streptococci)
2) Temporary colonisers (e.g. staph aureus, candida)
3) Pathogens: asymptomatic carriage vs infections, bacterial or viral
List some common bacterial and viral pathogens that infect the URT.
What are symptoms of influenza?
How is suspected/confirmed influenza managed?
Bacteria: Strep pyrogenes = Group A, Strep pneumoniae, Haemophilus influenzae. Uncommon = Corynebacterium diphtheriae, Neisseria meningitidis.
Viruses: Rhinovirus, Influenza/parainfluenza, Coronavirus, Adenovirus, RSV, Coxsackie, Enterovirus.
Fever, coryza (irritation and inflammation of mucous membrane inside nose -> stuffy, runny nose, sneezing, and post-nasal drip), systemic symptoms: headache, malaise, myalgia, arthralgia +-/ GI symptoms.
(pic)
How is influenza investigated in primary care compared to secondary care?
What is the standard treatement for influenza?
List some viruses and bacteria that can cause pharyngitis.
Case: 6 yo male, sore throat, fever, felt ill, tonsillar exudate, tender cervical nodes, rash (pic). What is the dx and what tx would you give?
What is a differential dx?
Primary = not needed. Secondary = nasopharyngeal swab for flu PCR.
Do not have to confirm infection before starting tx.
Within 48hr of start of symptoms: oseltamivir 75mg bd oral/NG x 5 d
Viruses: Common URTI viruses (e.g. rhinovirus, adenovirus, parainfluenza virus, RSV, coronavirus), EBV, CMV, HSV, [measles, HIV etc.]
Bacteria: Group A, B, B strep, Mycoplasma pneumoniae, Neisseria gonorrhoea, Corynebacterium diptheriae.
Rash = scarlet fever. Dx = group A strep. Tx = penicillin V x 10d and throat swab to find sensitivites.
EBV - can also present with rash (pic), however young adults likey to be symptomatic rather than children.
Describe how the Centor Criteria can be used to aid diagnosis of group A strep.
How is pharyngitis (group A strep) treated? List 2 complications.
What must you not prescribe if a pt has EBV?
One point for:
1) Tonsillar exudate
2) Tender cervical LN
3) Absence of cough
4) Hx fever
If 1/2 points - 20% chance of GAS, no rx. If 3/4 pts - 50% chance, rx advised.
Tx: abx (all are penicillin sensitive, most erythromycin sensitive (for penicillin allergies). Penicillin V 500mg qds for 10d OR clarithromycin 500mg bd for 10d.
Complications: rheumatic fever, glomerulonephritis.
Amoxicillin frequently causes rash in pts with EBV (NOT an allergy!), DO NOT GIVE AMOXICILLIN FOR SORE THROAT. Thus empitis rx for pharyngitis = penicillin V/clarithromycin.
List some viral and bacterial causes for acute otitis media (pic).
How is acute OM treated (child or adult)?
Viruses: common URTI viruses (rhinovirus, parainfluenza virus, infleunza, coxsackie, enterovirus, coronavirus,adenovirus, RSV etc.)
Bacteria: Strep pneumoninae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pnueumoniae, Strep pyrogenes. Bacterial OM can be v. severe. More likely to be viral than bacterial.
Children: no abx unless <2yo/symptoms persist >48h/high fever/bilateral/ottorrhea. Then amoxicillin (or co-amoxiclav) OR clarithromycin for 5-10d.
Adults: treat straight away: amoxicillin (or co-amoxiclav) OR clarithromycin. Complications: decreased hearing, mastoiditis, brain abscess.
What causes sinusitis (viral or bacterial)?
How is it managed?
Viruses: common URTI viruses (rhinovirus, parainfluenza virus, infleunza, coxsackie, enterovirus, coronavirus,adenovirus, RSV etc.)
Bacteria: Strep pneumoninae, Haemophilus influenzae, Moraxella catarrhalis.
Tx not usually necessary, consider co-amoxiclav, clarithromycin.
What are the 3 different types of pneumonia?
What are differentiates typical and atypical CAP?
What types of pnenumonia can you see in the 2 pictures?
Community acquired (CAP) - typical or atypical, Hospital acquired (HAP), Aspiration.
Typical: Strep pneumoniae, Haemophilus influenzae, Staph aureus, (M tuberculosis)
Atypical: Mycoplasma pneumoniae, Legionella, Chlamydia pneumoniae, Chlamydia psittacci
L: pneumococcal pneumonia
R: lobar pneumonia
What are some risk factors for pneumococcal pneumonia?
Mycoplasma pneumoniae causes atypical pneumonia. Describe it. What abx work best on it?
What does this chest radiograph show, and what rx would you use?
Recent influenza, alcohol, smoking/COPD, HIV. Abx resistance increasing!
Smallest free-living organism, no cell wall (not visible on Gram stain, unaffected by cell wall antibiotics (β-lactams); need to use macrolides instead). Autumn-winter, epidemics, dry cough, +/- pharyngitis, rhinorrhea, otalgia, hepatitis, meningitis.
Poorly defined nodular opacities in the R lower lung zone - Mycoplasma pneumoniae pneumonia. Not as pronounced as with pneumococcal pneumonia. Rx: macrolides (e.g. clarithromycin) OR quinolones (e.g. levofloxacin, ciprofloxacinn) OR tetracyclines (e.g. doxycycline).
Legionella spp can cause atypical penumonia. Describe them. What tx would you use to treat an infection (pic).
What can you see in the CXR?
What are the risk factors for this?
>50 spp, L pneumophila most common. G-ve rods. Require special media for growth (slow). Rx: Cell wall abx NOT effective. Use quinolones > macrolides > tetracyclines. Rifampicin added if severe. (pic)
S. aureus pneumonia with abscess (CAP)
Colonisation of URT. Usually follows viral URTI. PVL-toxin strain causes severe disease and necrotising/abscess formation.
Describe how you assess the severity of pneumonia with a score.
What tx would you give a score of:
0-1
2
>2
CURB65 - one point at inital assessment for: Confusion, Urea >7mmol/l, Resp rate >30/min, BP (systolic <90mmHg or diastolic ≤ 60mmHg), Age ≥ 65 yrs.
Score: 0-1 = low severity, death risk <3%, outpatient. 2 = moderate severity, death risk 9%, admit, microbiological ix, IV Rx. 3-5 = high severity, death risk 15-40%, urgent admission.
0-1: oral amoxicillin 500mg tds OR clarithromycin 500mg bd
2: IV benzylpenicillin 1.2g qds AND clarithromycin 500mg bd
>2: IV co-amoxiclav 1.2g tds (covers G-ve) AND clarithromycin IV 500mg bd
OR
IV ceftriaxone 2g od (good if pt been abroad) AND clarithromycin IV 500mg bd
Case 1
MD 76yoM, delirious, cough, productive yellow sputum, RR 27, BP 110/61, Urea 5.5, CXR (pic).
What do you see in the CXR?
Rx: raised WCC and CRP, low K+, ABG: T1RF, C(1), U(0), R(0), B(0), 65(1)
What is the dx and what would the tx be?
Hazy shadowing in the R base and L lower zone, hyperexpanded lung and fields.
CAP. CURB65 = 2. Tx: benzyl penicillin and clarithromycin.
Case 2
JR 49yoM IVDU/alcoholic, SOB, intermittantly drowsy, cough. Urea 7.1, RR 20, BP 117/69, CURB65 = 2. CXR (pic)
What do you see in the CXR?
What is the dx and tx?
RMZ and RLZ consolidation.
Pneumonia. Tx: co-amoxiclav and clarithromycin (b/c was quite sick and cover for possible aspiration b/c drug user who came in drowsy)
List the organisms which commonly cause HAP.
How is HAP treated?
G-ve organisms: E.coli, Klebsiella, Pseudomonas
G+ve cocci: Staph aureus
Same organisms as CAP
Mild/moderate - doxycycline. Severe - piperacillin - tazobactam (Tazocin).
Case 3
MK 55yo M, elective admission for L knee replacement performed on 24/9/15. Fevers, increased HR - a few days later. CXR (pic).
What can you see on the CXR?
What would be the dx and tx?
Consolidation L base.
Dx: HAP. Tx: piperacillin-tazobactam.
What is aspiration peumonia?
What are the 4 tx options?
What is ECOPD?
A relatively large amount of material from the stomach or mouth/URT enters the lungs. Usually low virulence organisms, polymicrobial - anaeriobes, aerobic strep.
1) Co-amoxiclav (covers anaerobes and CAPs)
2) Piperacillin-tazobactam (covers anaerobes)
3) Amoxicillin and metronidazole
4) Levofloxacin and metronidazole
* Metronidazole covers anaerobes*.
Exacerbation of COPD; worsening of symptoms: SOB, cough, sputum
Case 4
MS 44 yoF, 23 y smoking hx, asthma/COPD, worsening cough productive white sputum, wheeze and SoB, CXR (pic).
What would you prescribe?
Doxycycline.
What is empyema?
How is it treated?
How are respiratory infections prevented?
Effusion into pleural space adjacent to bacterial pneumonia, usually small and resolves with tx of pneumonia. BUT if complicated paraoneumonic effusion = bacteria invade plerural space -> empyema.
Drainage. Abx until CXR resolution (usually 2-4w).
Vaccinations (influenza, pneumoccal, Haemophilus influenza, Pertussis)
What is infective endocarditis, and where may it occur?
What is the most common cause of normal valve infective endocarditis? What are the risk factors?
What can cause an abnormal native valve? What is the most common cause of abnormal native valve infective endocarditis?
Infection of endocardial surface of the heart. May occur on normal valves, abnormal native valves, prosthetic valves. (pic)
Often highly pathogenic organisms: Staph aureus, Strep pneumoniae.
Risk factors: iatrogenic - infected cannulae etc., usually Staph aureus. IVDA (often leads to R sided endocarditis - Staph aureus, Yeasts, Pseudomonas app.)
Rheumatic fever, degenerative (calcific) disease, congenital defects (esp. turbulent flow), mitral valve prolapse.
Infection often due to low virulence bacteria: oral (viridans) Strep, Enterococcus spp, HACEK organism group and Coxiella burnetii, Chlamydia spp, Mycoplasma spp, Bartonella spp.
What is the most common cause of prosthetic valve infective endocarditis immediatly post-op, later, and one yr post surgery?
How is infective endocarditis treated?
What are the 2 types of antibiotic sensitivity testing?
Define MIC and MBC
Staphylococcus aureus (esp immediately post-op). Coagulase -ve Staph (often later presentation). One yr post surgery: oral (viridans) Strep, Enterococcus spp.
Vegetation impenetrable by phagocytes. Surgical backup essential. Synergistic combination. IV therapy essential: 4 weeks native valve IE, 6 weeks prosthetic valve IE. Need to know aetiology of infection - MIC of organism guides therapy.
(pic)
MIC: minimum inhibitory conc = lowest conc of antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation.
MBC: minimum bactericidal conc = lowest conc of antimicrobial that will prevent the growth of an organism after subculture on to antibiotic-free media.
What is the empirical therapy for endocarditis (native valve and prosthetic valve)?
Describe how a biofilm forms.
What is the directed therapy for infective endocarditis?
Only if severe sepsis:
Native valve: vanomycin and gentamicin OR vancomycin and meropenem (if risk of G-ve sepsis e.g. IVDU)
Prosthetic valve: vancomycin and gentamicin and rifampicin (to treat biofilm - cluster of bacteria in an extracellular matrix (slime) attached to surface (pic)).
Bacterial cluster -> lack of metabolic substrates -> waste accumultes -> enter slow/stationay phase -> more resistant to killing by abx -> bacterial cluster more (cycle)!
Staph: flucloxacillin 4 hrly (MRSA = vancomycin)
Strep: benzyl penicillin 4 hrly (resistance = vancomycin and gentamicin)
Enterococci: amoxicillin 4hrly and gentamicin.
