Infectious diseases Flashcards

Question

(CNS infection) Meningitis - state the following: - Pathophysiology - Common causative organisms (bacterial and viral) - Presentation - Investigations - Management

Answer 1

Pathophysiology: - Inflammation of the meninges Common causative organisms: - Can be bacterial or viral Bacterial: Neisseria Meningitidis or Streptococcus Pneumoniae Viral: Herpes Zoster, Varicella Zoster or Enterovirus Presentation: - Fever - Neck stiffness - Photophobia - Headaches - Vomiting - Altered consciousness - Seizures - Non-blanching rash (if meningococcal septicaemia) Investigations: - Routine bloods (FBC, U&Es, CRP) - Lumbar puncture - Meningococcal PCR test (blood test) - Blood cultures - Bacterial throat swabs Management: (Bacterial) - Give antibiotics within 1 hour: IV ceftriaxone 2g immediately (continued every 12-hours initially) - IV Dexamethasone 10 mg every 6 hours - Notify public health (notifiable disease) - may need to track close contacts within last 7 days (Viral) - Often milder, so supportive treatments - Can use Aciclovir for Varicella Zoster infections

Answer 2

1. Kernig's test - Bend leg to flexion at 90 degrees - Normal: no pain on straightening leg upwards - Abnormal: pain on straightening leg upwards 2. Brudzinski's test - Normal: neck lifted, legs remain flat/straight - Abnormal: neck lifted, hips and knees bend too

Answer 3

- Hearing loss (give steroids) - Seizures and epilepsy - Cognitive impairment and learning disability - Memory loss - FOcal neurological deficits e.g. limb weakness

Answer 4

Appearance Normal: clear Bacterial: cloudy Viral: clear Protein Bacterial: raised Viral: normal or mildly raised Glucose Bacterial: reduced Viral: normal WCC Bacterial: raised with neutrophils Viral: raised with lymphocytes Culture Bacterial: positive for bacteria Viral: negative

Answer 5

- Hearing loss - Seizures and epilepsy - Cognitive impairment and learning disability - Memory loss - FOcal neurological deficits e.g. limb weakness

Answer 6

Pathophysiology: - Inflammation of the brain parenchyma Common causes: Primary infection - most commonly viral: - Herpes simplex - Varicella zoster - MMR (measles, mumps and rubella) - Tick-borne encephalitis - Japanese encephalitis - Rabies Secondary infection - immune system: - Post-viral - Tumour - Post-vaccination Presentation: - Fever - Headaches - Vomiting - Altered consciousness - Focal neurological deficits - Seizures - Myalgia May also develop meningitis symptoms: neck stiffness and photophobia Investigations: - Routine bloods (FBC, U&Es, CRP) - CT or MRI head - Lumbar puncture - EEG (electroencephalogram) Management: Treat the cause! - Antivirals - Steroids - Plasmapheresis - Immunoglobulin therapy - Surgery to remove any tumours - Supportive therapy e.g. IV fluids, anti-epileptic medication, analgesia, oxygen

Answer 7

Pathophysiology: - Inflammation of the stomach and intestines (gastro & enteritis) Common causes: Mostly viral However, many bacteria can also cause gastroenteritis Presentation: - Nausea and vomiting - Diarrhoea - Fever - Abdominal pain Investigations: - Routine bloods (FBC, U&Es, CRP) - Stool culture with microscopy and sensitivties Management: Targeted towards underlying cause - Isolation of patient - Patient education regarding hygiene - Rehydration solution or IV fluids - 48 hrs away from school/work until symptoms have completely resolved - Antibiotics not given unless patient is at high risk of complications and once organism has been identified

Answer 8

Viral: - Norovirus - Rotavirus - Adenovirus Bacteria: - E Coli - Campylobacter Jejuni - Shigella - Salmonella - Bacillus Cereus - Yersinia Enterocolitica - Staphylococcus Aureus toxin Parasite: - Giardiasis

Answer 9

- Lactose intolerance - IBS - Reactive arthritis - Guillian-Barre syndrome

Answer 10

Pathophysiology: - Spore-forming anaerobic bacteria causing inflammation of the large colon Risk factors: - Recent antibiotic use (especially broad spectrum) - Recent stay in hospital - Immunosuppression - Previous infection with C.Diff - > 65 years Presentation: - Diarrhoea - Fever - Nausea and vomiting - Abdominal pain - Loss of appetite Investigations: - Routine bloods (FBC, U&Es, CRP) - Stool culture, microscopy and sensitivities Management: - Antibiotics, specifically oral Metronidazole or oral Vancomycin - Newer treatments: Faecal microbiota transplant

Answer 11

Pathophysiology: - Infection of the bladder - Usually E Coli which ascends from the urinary tract Risk factors: - Young - Sexually active - Female - Poor hygiene Presentation: - Urinary frequency - Nocturia - Suprapubic pain - Dysuria - Cloudy urine - Urgency - Fever - Haematuria Investigations: May not need further investigations - Urine dipstick Management: - Nitrofurantoin for 3 days (Trimethoprim second line) - If complicated, for 7 days

Answer 12

Pathophysiology: - Infection of the ureters and kidneys - Usually from E Coli which ascends from the urinary tract, further up to the kidneys Risk factors: - Young - Sexually active - Female - Poor hygiene Presentation: - Flank pain - Vomiting - High fever (other cystitis symptoms) - Haematuria - Urinary frequency - Nocturia - Suprapubic pain - Dysuria - Cloudy urine - Urgency - Fever Investigations: - Urine dipstick - Midstream urine sample for MCS - Blood cultures and assess for Sepsis Management: - Oral Co-amoxiclav for 10 days

Answer 13

Pathophysiology: - Infection of the skin and underlying soft tissues - Commonly caused by staph aureus Presentation: - Erythema (rubor) - Calor - Dolor - Tubor - Bullae (fluid filled blisters) - Tight skin - Gold-yellow crust (suggests staph aureus infection) Classification system: Eron classification Class 1: no systemic toxicity Class 2: systemic toxicity Class 3: significant systemic toxicity Class 4: sepsis / life threatening infection Investigations: - Bloods (FBC, U&Es, CRP) - Blood cultures Management: - Oral or IV Flucloxacillin (IV if class 3 or 4 Eron classification)

Answer 14

Pathophysiology: - Bacterial infection of the skin, soft tissue and fascia Presentation: - Generally features of sepsis - Pain out of proportion to site of injury - Fever Investigation / Management: - Immediate referral to surgical team for inspection, exploration and debridement of infected tissue (can use finger test) - Blood culture - Tissue culture - May need CT if unsure

Answer 15

Risk factors: - Abnormal distribution of pressures due to structural abnormalities (e.g. bunions, hammer or mallet toes) or gait abnormalities - Impaired protective mechanisms (e.g. dry skin, immune system abnormalities, peripheral artery disease) - Impaired recognition due to sensory neuropathy and/or visual impairments Presentation: - Local swelling - Erythema (>0.5 cm around the wound) - Localised pain - Localised warmth - Purulent discharge Investigations: - Routine bloods (FBC, U&Es, CRP) - Blood glucose measurement (consider HbA1c) - Pedal pulse examination or Doppler assessment - X-ray of foot - Tissue biopsy / sample Management: - Wound debridement and dressings - Offloading of foot (casts) - Antibiotics based off tissue sample, generally Flucloxacillin if mild infection (no abx if no evidence of infection) - Control of ischaemia e.g. angioplasty

Answer 16

Pathophysiology: - Infection within a joint itself - Can be in natural joint or as a complication of joint replacement Presentation: - Erythema - Swelling - Pain within joint - Hot joint - Reduced ROM and stiffness - Systemic symptoms: fever, fatigue and sepsis features Common causative organisms: - Staphylococcus aureus (most) - Neisseria gonorrhoea - Group A streptococcus - Haemophilus influenzae - E Coli Investigations: - Routine bloods (FBC, U&Es, CRP) - Joint aspiration and send for: gram staining, crystal microscopy, culture and sensitivities Management: - Treat as presumed septic arthritis until this has been disproved - IV empirical antibiotics until microorganism is known from joint aspiration - Flucloxacillin plus Rifampicin (first line) - Usually for 3-6 weeks *Consider joint washout and joint replacement if infection occurs in a prosthetic joint

Answer 17

- Gout - Pseudogout - Reactive arthritis - Haemarthrosis

Answer 18

Pathophysiology: - Infection of the bone (acute or chronic) - Children: generally in long bones of arms or legs - Adults: generally in hips, spine or feet - Primarily from bacteria in bloodstream, but can also be from nearby cellulitis or direct trauma (especially in DFI) Risk factors: - Recent open fracture or orthopaedic surgery - Poorly controlled diabetes - Immunosuppression e.g. chemotherapy - IV drug use - Peripheral arterial disease Presentation: - Erythema - Swelling - Pain in affected area - Hot joint Common causative organism: - Staphylococcus aureus (most) Investigations: - Routine bloods (FBC, U&Es, CRP) - Blood culture - Bone biopsy and sinus swab specimens - Plain x-ray of affected area (including joints above and below) or CT or MRI Management: - IV Flucloxacillin for 6 weeks (1st line) - If foreign body in place e.g. fixation metal, this is likely to be removed as a source of infection

Answer 19

- Oedema - Periosteal thickening - Osteopenia / bony lysis - Scalloped bone edges

Answer 20

Where did they travel? How long have the symptoms been present for? What symptoms do they have (which system is affected)? What activities did they do whilst travelling? Is anyone else in their travelling party affected? Did they have any healthcare treatment whilst travelling? Did they have any pre-travel vaccinations or prevention treatments

Answer 21

Routine bloods (FBC, LFTs, U&Es) Blood cultures Malaria films or rapid diagnostic test HIV test Urine and stool culture Chest x-ray or ultrasound of liver and spleen Serology / PCR for specific diseases (e.g. dengue or other arboviruses)

Answer 22

- Malaria - Viral hepatitis - Leptospirosis

Answer 23

- Dengue - HIV - Syphilis - Typhus

Answer 24

- Schistosomiasis - Strongyloides (threadworm)

Answer 25

- Shigella - Salmonella - Ameobiasis (Entamoeba histolytica)

Answer 26

- Malaria - Viral Hepatitis - Leptospirosis - Typhoid Fever

Answer 27

- Malaria - Visceral Leishmaniasis

Answer 28

Pathophysiology and mechanism of spread: - Infectious disease caused by parasites (plasmodium family) - Spread by bites of female anopheles mosquitoes, usually at night Countries with high risk: - Sub Saharan Africa - South-east asia Presentation: - Recent travel to country with high incidence of malaria - Jaundice / pruritus (from haemolytic anaemia) - Fever - Rigors - Headache - Myalgia - Nausea and vomiting (also hepatosplenomegaly) Investigations: - Routine bloods (FBC, U&Es, LFTs, CRP) - Malaria blood film (EDTA bottle) over 3 consecutive days - CT/ultrasound of liver - Serology to look for viral hepatitis and other diseases - Blood cultures (exclude other causes) Management: - Anti-malarial treatment once confirmed on blood film Uncomplicated malaria with Falciparum: Artemisinin based combination therapies (ACTs) = oral Riamet® Severe malaria: IV Quinine and Artesunate - Monitor blood films until parasite cleared

Answer 29

Plasmodium Falciparum (most severe type) Plasmodium Vivax Plasmodium Ovale Plasmodium Malariae

Answer 30

AKI / Renal failure Seizures Reduced consciousness Pulmonary oedema DIC Severe haemolytic anaemia Multiorgan failure and death

Answer 31

Malarone (Atovaquone/Proguanil): - Expensive - Best side effect profile Mefloquine: - Can cause bad dream and rarely, seizures or psychotic disorders Doxycycline: - Side effects of photosensitivity, diarrhoea and thrush

Answer 32

Describes a fever of above 38.3 degrees, lasting for > 3 weeks, that evades diagnosis Pyrexia of unknown origin can be considered in four categories: - Infective - Inflammatory / autoimmune - Malignancy - Miscellaneous

Answer 33

Bloods: - FBC - U&Es - LFTs - CRP - Erythrocyte sedimentation rate (ESR) as a marker of inflammation - Clotting screen - Creatine kinase - 2 or more blood cultures - HIV test. Imaging: - Chest X-ray - Ultrasound abdomen Other: - Urine dipstick Can do more specialised secondary tests once PUO is better understood / idea of category of PUO

Answer 34

Disease: - HIV infection - Haematological cancers / malignancies e.g. lymphoma or leukaemia - Autoimmune conditions e.g. RA, lupus, T1DM - Immunodeficiency conditions - Sickle cell disease (affects spleen) Medication: - Post-organ transplantation e.g. Mycophenolate Mofetil - Corticosteroids e.g. Hydrocortisone - Chemotherapy agents

Answer 35

Bacterial: - TB (pulmonary and extrapulmonary) - Mycobacterial infections - Encapsulated bacteria: streptococcus pneumoniae, haemophilus influenzae, Neisseria meningitidis - Non-typhoidal salmonellosis - Melioidosis - Syphilis Viral: - Arboviruses - Coxsackie virus, cytomegalovirus (CMV) - Epstein–Barr virus (EBV) - Parvovirus Fungal: - Aspergillosis - Candidiasis - Cryptococcosis - Endemic mycoses - Histoplasmosis - Pneumocystis jirovecii Parasitic: - Visceral leishmaniasis

Answer 36

Management should be supportive until the cause of pyrexia has been determined Therapeutic trials of antimicrobials or steroids are not recommended (can mask signs/symptoms of underlying disease process) Mortality of patients with PUO is generally low, especially patients that are seen as outpatients. Undiagnosed patients may be reassured that their prognosis is likely to be good, despite possible continuation of symptoms.

Answer 37

- Infections can be atypical and opportunistic (commensal bacteria can cause infection) - Infections can progress more rapidly - Infections can take longer to clear - Usual symptoms may be absent

Answer 38

- Oral candidiasis - Kaposi's sarcoma - Hairy leukoplakia - Pneumocystis jirovecii - Reactivation of TB

Answer 39

Clinical features (symptoms) - Reduced GCS / consciousness - Weakness meaning inability to walk without assistance - > 2 convulsions in 24 hrs - Very low blood pressure (< 80mmHg systolic) - Spontaneous bleeding Clinical findings (signs) - AKI - Hyperlactaemia / metabolic acidosis - Pulmonary oedema / sats < 92% / resp rate > 30 - Hypoglycaemia - Haemoglobinuria (Hb in urine) - Anaemia (severe and normocytic)

Answer 40

- Birth in a TB high prevalence country (Indian sub-continent and Sub-saharan Africa) - Prison - Drug and alcohol consumption - Poor/crowded housing or homelessness - Known contact with active TB - Previous TB disease

Answer 41

Interventions to improve and measure the appropriate use of antibiotics by promoting the optimal antimicrobial therapy e.g. dose, route, type - Minimise toxicity and other adverse events - Reduce cost of infections - Limit selectivity for resistant strains

Answer 42

Rifampicin (red-an-orange pissin) - Orange urine/tears - Hepatitis + Isoniazid (I'm so numb-a-zoid) - Peripheral neuropathy - Hepatitis ++ GIVEN WITH PYRIDOXINE (B6) to prevent peripheral neuropathy Ethambutol (eye-thambutanol) - Optic neuropathy / reduced visual acuity Pyrazinamide - Hepatitis +++ (most severe) - Hyperuricaemia / gout

Answer 43

Pathophysiology: - Hepatitis B virus causes acute inflammation of liver, most don't progress to chronic inflammation - Transmission: blood/sex/vertical Presentation: Acute infection - Abdominal pain - Intrahepatic jaundice - Nausea and vomiting - Arthralgia - Fatigue - Deranged LFTs Investigations: - Hepatitis B serology Management: - No cure - Can use lifelong anti-retrovirals - Vaccination available for prevention

Answer 44

Pathophysiology: - Hepatitis C virus causes acute inflammation of liver, which mostly progresses to chronic inflammation - Transmission: blood/sex/vertical Presentation: - Most people have no symptoms in acute or chronic phase Investigations: - Hepatitis C serology (just anti-Hep C antibody) Management: - Cured with anti-viral drug combination - No vaccination available

Answer 45

Pathophysiology: - Mycobacterium tuberculosis bacteria - Inhaled through droplets of an actively infected individual - Spreads through the lymphatics and blood - TB can be active or latent Common extrapulmonary colonisation sites: - Lymph nodes - Pleura - Pericardium - GI system - Genitourinary system - Subcutaneous - CNS - Bones and joints Presentation: - Weight loss - Night sweats - Cough +/- haemoptysis - Lethargy - Erythema nodosum - Lymphadenopathy - Spinal pain (if spinal TB) Investigations: - Mantoux test or QuantiFERON gamma - Sputum cultures (if suspect active disease) - Chest x-ray (if suspect active disease) Management: Acute pulmonary TB: RIPE - Rifampicin - Isoniazid (plus Pyridoxine) - Pyrazinamide - Ethambutol Latent TB (at risk groups): 3 months of Rifampicin and Isoniazid OR 6 months of Isoniazid Other: - Test for other infectious disease e.g. HIV, Hepatitis - Notify Public Health - Contact tracing - Isolation in -ve pressure rooms

Answer 46

Mantoux test: - Looks for previous immune response to TB - Inject Tuberculin (protein from TB) - Positive result (bleb under skin) indicates previous exposure to TB - This includes active TB, latent TB or previous BCG vaccination QuantiFERON: - Mix blood sample with TB antigens - Positive result is release of interferon gamma by white cells (indicates previous exposure) QuantiFERON can be used to confirm latent TB, in someone with a positive Mantoux test but no active disease

Answer 47

Pathophysiology: - Human immunodeficiency virus (HIV-1 most common), RNA retrovirus - Virus enters and destroys CD4 cells - Initial seroconversion, then asymptomatic until further along and immunocompromised Transmission: - Unprotected sex (oral, vaginal, anal) - Vertical transmission - Exposure to infected blood e.g. needlestick, blood splash in eye Presentation: - Initial flu-like symptoms (seroconversion) - Generally asymptomatic for a period of years - Symptomatic with atypical or opportunistic infections e.g. PCP or candidiasis Investigations: - Antibody blood test - Can also do a PCR test Management: - Anti-retroviral treatment (ART) - Single tablet once daily - Recommended 2 NRTI and 1 other agent - Aim of treatment: undetectable viral load and normal CD4 count Monitor disease with CD4 count (<200 is end-stage HIV/AIDS) and viral load

Answer 48

Occurs when CD4 count has dropped significantly - Kaposi's sarcoma - PCP (pneumocystis jirovecii pneumonia) - TB - Candidiasis (oesophageal or bronchial) - Cytomegalovirus infection - Lymphomas

Answer 49

- Nucleoside reverse transcriptase inhibitors (NRTI) - Integrase inhibitors (II) - Protease inhibitors (PI) - NON-nucleoside reverse transcriptase inhibitors (N-NRTI) - Entry inhibitors (EI)

Answer 50

Prophylactic Septrin - prevent pneumocystis jirovecii pneumonia (PCP) if CD4 < 200 Yearly cervical smears - increased risk of HPV and cervical cancer Up to date vaccinations, including: - Flu - Pneumococcal - Hepatitis A and B - Tetanus - Diphtheria - Polio