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Infectious Diseases finalsinfocus@gmail.com MattDowthwaite @finalsinfocus @finalsinfocus HugoOxfordIn t r o d u c ti o n : _pdf-85707770.pdfk.org/-/media/documents/mla-content-map- mediBristol and junior doctorssity of Aiming to provide free, high yield, MLA ssturevision series on Zoomday nightl Follow us on social media for daily MCQs arevision scheduledate with our Pleorder to receive the slides!k formin Question 1 A 31-year-old female presents to A&E with one week of dry cough and breathlessness. These symptoms Given the likely diagnosis, which of the following organisms is the most likely cause of this patient’s symptoms? were preceded by 2 weeks of coryza which has now settled. A. Streptococcus pneumoniae She has no PMHx and takes no regular medications. Observations unremarkable. B. Haemophilus influzae O/E you find multiple target-like lesions on her limbs and trunk. C. Staphylococcus aureus D. Legionella pneumophillia E. Mycoplasma pneumonia Bonus Question: What is the rash being described and which other conditions can it be seen in? • Erythema multiforme: usually caused by infections including HSV-1 and 2, CMV, EBV, influenza, Covid infection#:~:text=pneumoniae%20may%20occasionally%20cause%.0bullous,then%20spreads%20to%20the%20trunk Table1: Pneumonia CausativeOrganism Specific associated features I n t r o d u c t i o n : Mycoplasma • Prolonged insidious onset • Arthralgiaultiforme • Usually bacterial but it can be viral or fungal • Haemolyticanaemiacarditis • Importantly, for exams look out for these key features in the stem of Legionella • Te.g. ACincheap accommodationling systems, the MCQ (see table) • Pchest symptomsia, headache+ fever before • Can be split into CAP, or HAP – pneumonia contracted >48 hrs after • Hyponatraemia secondarytoSIADH hospital admission. HAP usually has worse outcomes. Klebsiella • ‘Red-current jellysputum’cs • Hospital workout will include a CURB-65 score (CRB-65 if primary Pseudomonas • Opportunistic, rarelycauses diseaseinhealthy care) to stratify risk, as well as CXR, bloods, sputum cultures, • Think Pseudomonas ifBG ofCF/bronchiectasis for assessing treatment responseary antigen tests, CRP monitoring Pneumocystis jirovecii • FormerlyPCP– Funginsputum • Hypoxia + raised LDHs • Life-threatening Criteria Marker C Confusion U Urea>7mmol/L R Resprate>=30/min B BP:diastolic<=60 65 Age>=65Question 2 I n t r o d u c t i o n : and confusion. He is also mildly sensitive to light. A.atViral meningitisely cause of this patient’s symptoms? puncture:wing results were obtained after lumbar Clear appearance B. TB meningitis RBCs 23 (85% lymphocytes, 15% polymorphs) C. Encephalitis CSF protein 0.9g/Lerum 4.9)tain D. Bacterial meningitis E. Fungal meningitis https://en.wikipedia.org/wiki/Lumbar_punctureIeningitit r o d u c t i o n : Meningitis = inflammation of the meninges Features to look out for = • Headache • Nausea + vomiting • Seizuresffness • Non-blanching rash Mx of viral meningitis = • Any question re whether could be bacterial, start on broad Age Group Most common cause ofmeningitis • V7-14 daysngitis is self-limiting, with symptoms resolving in 0-3months GroupBstreptococcus Mx of bacterial meningitis = 3months–6years Neisseriameningitidis • Lgive ABX first (after blood cultures)or contraindicated, 6-60years Neisseriameningitidis • IV ABX -- > 50 years cefotaxime (of ceftriaxone) + amoxicillin >60years Streptococcuspneumoniae • IV dexamethasone IQnestiot 3r o d u c t i o n : from India is found to have a positive Mantoux skin What is the most likely treatment option for this patient? She does not have any active signs of tuberculosis. A. +pyridoxine for 6 monthsethambutol + pyrazinamide B. No treatment C. Isoniazid alone for 3 months D. Rifampicin alone for 3 months E. Isoniazid + pyridoxine for 6 months https://en.wikipedia.org/wiki/Ziehl–Neelsen_stain Treatment Side effect Tuberculosis I n t r o d u c t i o n : Rifampicin • P450 inducerions • Hepatitis / flu like symptoms • mycobacterium tuberculosisnulomatous disease caused by the bacteria Isoniazid • (‘imsonumb’azid) –preventwith • It is estimated that 1.8 billion people have latent TB infection • Hepatitis, agranulocytosis • P450 inhibitor • nodes. Leads to formation of small granulomas that can heal or lay Pyrazinamide • Arthralgia, myalgiat dormant (latent disease) • Hepatitis • Features: Causes a wide array of symptoms affecting multiple systems, Ethambutol • ‘Eye’thambutol abroad in high TB area, + bloodstained sputum.e travel history / living Diagnostic investigation forACTIVETB Findings 1. Treatment: Active TB • Continuation phase – Rifampicin, isoniazid - next 4 months ChestX-ray • Bilateral hilarlymphadenopathy Sputum smear • Staining with Ziehl-Neelsen stain, for • 3 months of isoniazid (+ pyridoxine) and rifampicin or Sputum culture • Gold standard acid-fast bacilli • 6 months of isoniazid (+pyridoxine) • Can take1-3 wks • Screening for latent TB NAAT (nucleic acidamplification tests) • Allows for rapid diagnosis • previous TB exposuredermal tuberculin injection – 5mm or more = • Interferon gamma release assayIntro du c io n: Causes of upper lobe fibrosis – A TEA SHOP T uberculosisnchopulmonary aspergillosis A nkylosing spondylitiseolitis (hypersensitivity pneumonitis) S arcoidosis O ccupational (silicosis) P neumoconiosisIunstiont4 r o d u c t i o n : A 49-year-old man present to A&E with a 3-week organisms is not a typical cause for this condition? history of night sweats, fever and weight loss. A. Esherichia Coli On examination, you note the patient’s temperature loudest over the left, lower sternal border.ard B. Staphylococcus aureus Observations as follows: C. Kingella kingae Temperature: 38.7 D. Eikenella corodens BP: 145/85 E. Streptococcus ViridiansInfecIine Endotarritio d u c t i o n : Causes of Infective Endocarditis Common Staphylococcus aureus (most common) • Iof the heartocarditis = infection of the the endocardium (inner lining) Enterococcius viridians (developing countries) Less common Haemophilus spp Ø Valvular heart disease Cardiobacterium spp Ø Structural congenital heart disease Kingella kingae Ø Hypertrophic cardiomyopathyitis Ø Intravenous drug users Modified Dukes Criteria Ø Pathological criteria positiveiagnosis needs… Pathological Positive histology or material obtained at Ø 1 major, 3 minor criteria Major Positive blood culturesery Ø 5 minor criteria (positive echo/new valvularolvement • Treat with IV ABX in concurrence with guidelines + culture results regurgitation) Ø Ftreatment is amoxicillin +/- gentamycinsults) with a native valve, Minor Fever>38sing heart condition/IV drug use haemorrhages, Janeway lesions splinter glomerulonephritis, Osler’s nodes, Roth spotsIunstiont5 r o d u c t i o n : taking his temperature at home, it has reached up to 39.5n Which organism is the most likely causative agent of this degrees. patient’s symptoms? photophobia.re is no associated neck stiffness orche and A. Legionella spp. He has no recent travel history but keeps livestock on his B. Bartonella henselae O/E, mild crackles were heard on chest auscultation, otherwise unremarkable. C. Coxiella burnetti markers, ALT and AST. were normal apart from a raised liver D. Mycoplasma pneumoniae E. Borrelia burgdorferi Coxiella burnetti cause?ndition does infection with A. Q FeverQ FIvnr t r o d u c t i o n : Lyme Disease • Lyme disease is a bacterial infection caused by infected • Q fever is an infection caused by the bacterium ticks carrying the bacteria Borelia burgdorferi Coxiella burnetti • present or with antibodies to Borelia burgdorferians is • famers who look after cattle and sheep. abattoir / • Standard treatment is with doxycycline • Features: ØHeadaches ØHeadachesins Features of Lyme disease • Importantly, a transaminitis is also usually seen (within 30 days) Headache migrans – bullseye rash transaminases (ALT, AST)o elevated levels of the Feverrgy • Treatment is with doxycycline Arthralgia (after 30 days) peri/mycarditis– heart block, radicular pain, meningitise palsy,Question 6 I n t r o d u c t i o n : The pregnancy has been uncomplicated so far. booking scan. following would best describe her HBV status? of the the following results:or her to have hepatitis B serology, with A. Previous acute HBV infection HBsAg – Positive B. Current acute HBV infection Anti-HBcAg IgM – Negative Anti-HBcAg IgG - Postive C. Current chronic HBV infection D. Previous HBVimmunisation with a good response E. Previous HBV immunisation with a poor response Type of hepatitis Route of transmission Treatment Hepatitis A Faecal-oral No treatment / HepItinis B t r o d u c t i o n : conservative • Hstranded DNA virus)ion of the liver caused by the hepatitis B virus (double Hepatitis B fluidsand other bodily alphaated interferon- Hepatitis C Blood Protease inhibitors 1. Feveres: Hepatitis D Blood and other bodily Interferon 3. Elevated liver transaminases people already infected with Hep B) • Serology Hepatitis E Faecal-oral No treatment / Marker Meaning conservative HBsAg (surface antigen) Active infection (1-6 months) Complications: Chronic infection (>6 months) Anti-HBs (antibody to Hep B surfaceantigen) Immunity (eithervia exposureor • Fulminant liver failureund glass hepatocytes’ -remember: vaccineis surfaceantigen, so • Hepatocellular carcinoma - Will be negative in chronic disease • Polyarteritis nodosa Anti-HBc (antibody to Hep B coreantigen) Previous of current infection Treatment: IgM Anti-HBc (IgM core antibody) infection –presentfor 6 monthsHep B • Pegylated interferon-alpha IgG Anti-HBc (IgG coreantibody) This antibody persists after6 months HBeAg (eantigen) Marker of infectivity –results from the cells.own of core antigen in infected liverQuestion 7 I n t r o d u c t i o n : up. He reports that he feels well and has an undetectableeck- What additional prophylactic medication should this He has no relevant past medical history and only takesltegravir. patient be started on? paracetamol occasionally for tension type headaches. A – Prednisolone bpm, his blood pressure is 131/86 mmHg and his oxygenate is 69 B – Rifampicin saturations on air are 98%. C – Aciclovir His bloods are taken in clinic and his CD4 count is 145/mm D – Co-trimoxazole E- Erythromycin Other AIDS defining illnesses to be aware about: HIV IDn Count t r o d u c t i o n : • Cytomegalovirus infection Pathophysiology of HIV • Candidiasis (oesophageal or bronchial) • HIV is a retrovirus meaning that its genetic material is RNA, opposed to DNA, as • Tuberculosis • HIV affects CD4 cells by initially binding to the CD4 receptor on the surface of • Toxoplasmosis • It then uses reverse transcriptase to convert viral RNA into DNA before using integrase to gain access to the nucleus of the cell •erocRefers to the period during which an individual becomes infected with HIV • own RNA polymerasehen embedded into the CD4 cell DNA through use of CD4’s • Typically occurs a few weeks – months after initial exposurest the virus • Transcription and translation then occur leading to mRNA release from the CD4 • This immune response and creation of antibodies causes a number of • This process can lead to the death of the CD4 cell or make it dysfunctional. maculopapular rash, mouth ulcers, malaise, myalgiadenopathy, • This means that CD4 cells can’t carry out their typical immune functions = immunosuppression Investigations CD4 count and HIV • p24 antigen can be detected as early as 2-3 weeks after exposure • The CD4 count is a measure of how many CD4 cells are present in a cubic • monthseople develop antibodies to HIV at 4-6 weeks but 99% do by 3 • When the CD4 count falls below 200 cells/mm³, the risk of developing • The sensitivity of these fourth-generation tests approaches 100% forsts opportunistic infections increases significantly patients with chronic HIV infection • These opportunistic infections are known as AIDS defining illnesses • days after exposure, a negative result is reliable.eliable. More than 45 So why is the answer Co-trimoxazole? • When a patients CD4 count falls below 200, one of the infections they’re at risk • Presents with dry cough, dyspnoea and very few chest signs. Often in exam questions patients will have an exercise induced desaturation • ability to penetrate the cyst wall of the organismcystis jiroveci due to itsQuestion 8 IA 17-year-old male presents to his GP complaining : of a sore throat and headache over the last week. counsel this patient about? what is most important to and was accompanied by malaise and fatigue. throat A – Avoid ibuprofen On examination, his tonsils are erythematous and B – Advise staying off school for 1 week covered in exudate. He also has cervical C – Restrict fluid intake reveals swollen axillary lymph nodes and a palpable E – Symptoms should resolve in 48 hours mass in the left hypochondriac region. His observations are BP 122/84, temp = 38.1, HR = 78, RR = 14 Bloods reveal a lymphocytosis and positive monospot test InfIcnious Mtnorucloosis d u c t i o n : This patient has glandular fever aka infectious mononucleosis: • and pyrexia triad seen in 98% of patients is sore throat, lymphadenopathy • A maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis •voiOne of the most significant complications of glandular fever is splenic infection, tears or ruptureshe spleen, usually enlarged due to the • work harder to filter the blood alongside lymphocytosis causing fluid to Other features of management and counselling patients • Symptoms usually last for 2-4 weeks • Arrange hospital admission if patient has stridor, dehydration or • Avoid kissing and sharing eating utensils to limit spread of the diseaseQuestion 9 I n t r o d u c t i o n : A 35-year-old male presents to his GP following a 1-month volunteering Which organism has most likely caused this presentation? trip to sub-Saharan Africa. A- Plasmodium falciparum to the UK. He is concerned as his fevers have increased in frequency and B – Plasmodium malariae are now present every 48 hours. weakness and non-specific muscle pain. He also reports that over the C – Plasmodium vivax times.eek he has felt much more nauseous and has vomited several D - Schistosoma haematobium His cardiorespiratory examination is normal, but he has splenomegaly E – Flaviviridae RNA virus on palpation of the abdomen. His observations are in normal range. Investigations Malaria • Thrombocytopaeniaood films are diagnostic I n t r o d u c t i o n : • AKI – due to hemoglobinuria, hypovolemia, or sepsis. This patient is presenting with features of Malaria: • In severe stages can lead to hypoglycaemia and metabolic acidosis • High fever and rigors is a cardinal feature of P. falciparum • Headachen – always look out for fluctuating / periodic fevers •anaP.falciparum is treated with artemisinin-based combination • diarrhoea can also be presentvomiting most common but • destruction of malaria parasites through the generation of reactive • Fatigue and myalgia • Activated by iron – targets erythrocytes • the spleen has to process more debris / dead RBCs meaning • Foreign travel – specifically Sub-Saharan Africa (about 85% of Prophylaxis all cases) • Use nets / spray as wellxycycline, or mefloquine • sickle cell, G6PD deficiencyre worth mentioning here too such as Complications • Acute renal failure: blackwater fever, secondary to intravascular • Acute respiratory distress syndrome (ARDS) • Disseminated intravascular coagulation (DIC)UK NoIifnable t r d u c t i o n : Diseases •Acute encephalitis •Acute meningitis hepatitis •Botulismliomyelitis •Choleraosis •Enteric fever (typhoid or paratyphoid fever) •Haemolytic uraemic syndrome (HUS) •Legionnaires’ diseaseptococcal disease •Malaria •Monkeypoxccal septicaemia •Plague •Severe Acute Respiratory Syndrome (SARS) •Smallpoxfever •Typhusulosis •Whooping coughagic fever (VHF) •Yellow feverAny Questions? 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