Infections Flashcards
What are the two most common causative pathogens in Infective Endocarditis?
- a-Haemolytic Streptococcus
2. Staph. Aureus
What are the risk factors for Infective Endocarditis?
- Prosthetic valves
- Rheumatic fever (damaged valves)
- IVDU (needles contaminated with bacteria- primarily affects tricuspid valve as users inject into venous system)
- History of endocarditis
Which valves are most commonly affected by Infective Endocarditis?
Aortic and Mitral valves
Tricuspid in IVDU as they inject into venous system
What causes Non-bacterial Thrombotic Endocarditis and what is its clinical importance?
Occurs in a hypercoagulable state:
- Cancer (advanced malignancy)
- DIC
- Sepsis
Clinically important as it results in emboli.
What are the symptoms of Infective Endocarditis?
Fever Chills Night sweats Headaches SoB on exertion Tiredness Heart failure symptoms can be caused by a regurgitant valve.
What are the signs of Infective Endocarditis?
Murmurs
Tachycardia
Splenomegaly
Skin: Splinter Haemorrhages, Petechiae, Janeway lesions (5%), Osler’s nodes (15%)
Roth Spots
Renal: Microscopic heamaturia, renal impairment
Clubbing (in longstanding disease only)
What is the diagnostic criteria for Infective Endocarditis?
DUKES Classification:
- Major criteria:
1) +ve blood culture of typical organism from two separate tests.
2) +ve echocardiogram showing evidence of endocardial involvement via vegetation, an abscess, or new valve regurgitation. - Minor criteria (5/6 if no major criteria):
1) Predisposing condition or IVDU
2) Fever
3) Vascular phenomena- emboli etc.
4) Immunological phenomena- osler’s nodes etc.
5) Microbiological evidence= +ve culture
6) Endocardiogram not quite meeting major criteria
Infective Endocarditis investigations and results?
WCC increased Urea and Creatinine increased ESR raised, high CRP raised Urine: Proteinuria, microscopic haematuria (50%)
Infective endocarditis treatment?
Abx for 4-6 weeks.
- Gradual onset- unlikely staph- Benzylpenicillin + Gentamicin
- Acute onset/ skin trauma- Flucloxacillin + Gentamicin
- Resistance/ staph (recent valve replacement or IVDU)- Vancomycin + Gentamicin
What are the possible complications of Infective Endocarditis?
Myocardial abscess- suppurative pericarditis
Valve rupture
Systemic emboli- Left side= kidney infarct, irght side= PE
What are the common causative organisms for an infection of the nasopharynx?
Rhinovirus
Coronavirus
Staph. Aureus
What are the common causative organisms for an infection of the oropharynx?
Group A strep.
Diptheriae
Epstein-Barr virus
Adenovirus
What is the most common causative organism for an epiglottitis infection?
Haemophilus influenza type B
What are the common causative organisms for an infection of the middle ear (otitis media)?
Haemophilus influenza
Strep. Pneumoniae
Staph. Aureus
What are the common causative organisms for an infection of the sinuses?
Haemophilus influenza
Staph. Aureus
What is the most common causative organism for an infection of the pharynx?
Strep. Pyogenes
What is the presentation of acute bronchitis?
Cough
SoB
Wheeze
Pyrexial
What is the cause of acute bronchitis, and does it require treatment?
Most commonly viral (Will present with purulent sputum if bacterial)
Usually self-limiting
What is the presentation of pneumonia?
Productive cough with purulent sputum (if bacterial, which it usually is) and possibly haemoptysis
Pleuritic chest pain
SoB
Fever
Malaise
Anorexia
May be: Confused, tachypnoeic, tachycardic, hypotensive
What are the chest signs in pneumonia?
Expansion reduced Percussion dull Vocal resonance increased Bronchial breathing Pleural rub
How is a pneumonia diagnosis confirmed?
CXR
What are the common causative organisms for CAP?
- Strep pneumoniae (gram +ve) (rust coloured sputum)
- Haempohilus influenzae (gram -ve)
- Moraxella catarrhalis (gram -ve)
What is the scoring system used to gauge the severity of a CAP infection and what are its components?
Confusion (AMT < 8) Urea > 7 mmol/L Resp. rate >30 bpm Blood pressure < 90mmHG sys/ < 60mmHg dias 65 years old or greater (Score correlated to mortality and used for admission) 0-1 = outpatient 2 = inpatient 3 or more = consider ICU
What is the definition of a HAP?
Pneumonia acquired 48hrs after admission
What are the most common causative organisms of a HAP?
Most commonly gram -ve enterobacteriae: E. Coli Klebsiella pneumoniae Pseudomonas aeruginosa (CF) Staph. Aureus
What is the most common cause of tuberculosis?
Mycobacterium Tuberculosis (large non-motile rod shaped gram +ve bacterium) Obligate aerobe therefore found in the well ventilated upper lobes
How does TB spread?
Via airborne droplet nuclei
What it the pathogenesis of TB?
Droplet nuclei inhaled, travel to alveoli (not v infectious, need 8 hrs/ day contact)
2-8 weeks: Macrophages ingest/ surround the bacilli, forming granulomatous inflammation.
If the immune system cannot contain the bacilli they multiply rapdily causing active TB (which is infectious)
What are the symptoms of TB?
Persistent cough >3 weeks with sputum/ heamoptysis (gradual onset) Dyspnoea Weight loss Drenching night sweats Fever Lethargy Unexplained pain Extra-pulmonary TB (usually non-infectious): Swollen lymph nodes, weakened bones, abdo pain, vomiting, diarrhoea, rectal bleeding, headache, confusion, blurred vision
What are the clinical signs of TB?
Pleural effusion Cervical lymphadenopathy Mediastinal/ hilar lymphadenopathy Cachexia Ascites Mono-arthritis
What investigations are used to diagnose TB?
Interferon Gamma release assays
Mantoux test (false +ve if BCG vaccinated, false -ve if very recent infection)
Multiple sputum samples
CXR- consolidation + cavities in mid/upper zones
CT scan- ‘tree in bud’ sign- airway obstruction due to infection
How does the BCG vaccine work?
Made from attenuated mycobacterium bovis.
70-80% effective
How is TB treated and what are the side effects?
2 months of: Rifampicin Isoniazid Pyrazinamide Ethambutol 4 further months of : Rifampicin Isoniazid Side effects: Itching, rashes, nausea & vomiting, peripheral neuropathy, colour blindness, hepatitis
What is the most common cause of Acute Cholecystitis?
Gallstones blocking the cystic duct.
What are the symptoms of Acute Cholecystitis?
Biliary colic- RUQ pain/epigastrium pain- radiates towards the right scapula (Boas’ sign- right phrenic nerve irritation)
Tender/ swollen/ hot
Worse on breathing/ moving
Worse on eating fatty foods (gall bladder stimulated to contract by CCK from the pancreas)
Nausea+ vomiting
Diarrhoea
What are the clinical signs of Acute Cholecystitis?
Murphy’s sign +ve: Place hand below right costal margin and ask patient to breath in. They will catch their breath as their gallbladder hits your fingers.
Fever
*Courvoisier’s law: Painless enlarged gallbladder + jaundice is unlikely to be gallstones, more likely cancer of lower biliary tree.
What investigations give abnormal results in Acute Cholecystitis?
WCC increased
AST raised
ALT raised
How is Acute Cholecystitis managed?
Broad spectrum abx
Cholecystectomy (if symptomatic)
Which organisms can cause complications in an inflammed gallbladder?
*KEEP* (infectious organisms of the gut) Klebsiella pneumoniae E. Coli Enterococcus Pseudomonas legionella
What are the symptoms of Ascending Cholangitis?
Charcot’s Triad:
- RUQ pain
- Fever (rigors)
- Jaundice (due to obstruction of common bile duct)
What are the symptoms and signs of meningitis?
Headache
Pyrexia
Photophobia
Non-blanching rash (if meningococcal)
Neck stiffness
Focal Signs (hemiparesis/ opthalmoparesis)
+ve Kernig’s sign (inability to straighten leg when hip flexed to 90 degrees and neck/back pain when attempted)
How does a meningitis history proceed?
Prodrome (fever, lethargy etc.)
Meningism (headache, photophobia, neck stiffness etc.)
Raised ICP (drowsiness, irritability etc.)
Sepsis
What are the main bacterial causes of Meningitis?
Neisseria meningitides (meningococcus) Strep. pneumonia (pneumococcus) Listeria monocytogenes Haemophilus influenza Mycobacterium tuberculosis (insidious onset 1-9 months)
What are the main viral causes of meningitis?
Cytomegalovirus Herpes simplex Varicella zoster Enterovirus HIV
What are the other causes of meningitis?
Fungal: cryptococcus neoformans
IV Amphotericin B 14 days then PO Fluconazole 8 weeks
Protozoa Helminths (worm)
What changes to WBCs, Protein and Glucose would be seen on LP for meningitis caused by:
- Bacteria
- Virus
- TB
- Malignancy
Bacteria= WBC markedly raised, Protein usually elevated, Glucose reduced Viral= WBC raised, Protein often elevated, Glucose normal TB= WBC elevated, Protein usually elevated, Glucose reduced Malignant= WBC elevated, Protein elevated, Glucose reduced
How is meningitis managed?
Pre-hospital:
1.2g Benzylpenicillin IV/IM (1g cefotaxime if allergic)
1L IV fluid over 15 mins
Oxygen
Hospital:
ABC- 100% Oxygen, IV fluid, 2g cefotaxime
(If elderly/ suspected listeria also give 2g/hr ampicillin/ amoxicillin)
*If septic, don’t LP and instead give 2g cefotaxime and contact the critical care team.
Viral= aciclovir 10mg/Kg TDS
What are the signs and symptoms of Encephalitis?
Focal neurology e.g. dysphagia Seizures Headache Fever (High mortality if untreated- 70%)
What’s the most common cause of Encephalitis?
Viral e.g varicella
TB, autoimmune can also be responsible
What is Status Epilepticus?
30 min continuous seizure/ multiple seizures over 30 mins without regaining consciousness
How do you manage Status Epilepticus?
ABC
Lorazepam 1-2mg IV
Phenytoin 15-30mg/kg loading dose then 100mg TDS
Fosphenytoin
Thiopentone/ propofol infusion- paralyse and ventilate (ITU)