Infectious diseases Flashcards

Question

Hepatitis B

Answer 1

- Pegylated Interferon alpha - Antiviral Medications TENOFOVIR( NRTI) ENTECAVIR ( HBV DNA polymerase inhibitor) TELBIVUDINE (a synthetic thymidine nucleoside analogue)-

Answer 2

Clostridioides difficile: spreads via the faecal-oral route by ingestion of spores.

Answer 3

If a patient has had 5 doses of tetanus vaccine, with the last dose < 10 years ago, they don't require a booster vaccine nor immunoglobulins, regardless of how severe the wound is. -Tetanus vaccine is currently given in the UK as part of the routine immunisation schedule at: 2 months 3 months 4 months 3-5 years 13-18 years - Patient has had a full course of tetanus vaccines, with the last dose < 10 years ago no vaccine nor tetanus immunoglobulin is required, regardless of the wound severity Patient has had a full course of tetanus vaccines, with the last dose > 10 years ago if tetanus prone wound: reinforcing dose of vaccine high-risk wounds (e.g. compound fractures, delayed surgical intervention, significant degree of devitalised tissue): reinforcing dose of vaccine + tetanus immunoglobulin If vaccination history is incomplete or unknown reinforcing dose of vaccine, regardless of the wound severity for tetanus prone and high-risk wounds: reinforcing dose of vaccine + tetanus immunoglobulin

Answer 4

Listeria monocytogenes is a Gram-positive bacillus that has the unusual ability to multiply at low temperatures. It is typically spread via contaminated food, typically unpasteurised dairy products. Infection is particularly dangerous to the unborn child where it can lead to miscarriage. Investigation 1- Blood cultures 'tumbling motility' on wet mounts 2- Cerebrospinal fluid findings: pleocytosis, often lymphocytes (nontuberculous bacteria usually cause a rise in neutrophils) raised protein reduced glucose Management Listeria is sensitive to amoxicillin/ampicillin (cephalosporins are usually inadequate) Listeria meningitis should be treated with IV amoxicillin/ampicillin and gentamicin.

Answer 5

Bacillus cereus characteristically occurs after eating rice that has been reheated

Answer 6

HIV: Pneumocystis jiroveci pneumonia Whilst the organism Pneumocystis carinii is now referred to as Pneumocystis jiroveci, the term Pneumocystis carinii pneumonia (PCP) is still in common use Pneumocystis jiroveci is an unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa PCP is the most common opportunistic infection in AIDS all patients with a CD4 count < 200/mm³ should receive PCP prophylaxis Features dyspnoea dry cough fever very few chest signs Pneumothorax is a common complication of PCP. Extrapulmonary manifestations are rare (1-2% of cases), may cause hepatosplenomegaly lymphadenopathy choroid lesions Investigation CXR: typically shows bilateral interstitial pulmonary infiltrates but can present with other x-ray findings e.g. lobar consolidation. May be normal exercise-induced desaturation sputum often fails to show PCP, bronchoalveolar lavage (BAL) often needed to demonstrate PCP (silver stain shows characteristic cysts) Management co-trimoxazole IV pentamidine in severe cases aerosolized pentamidine is an alternative treatment for Pneumocystis jiroveci pneumonia but is less effective with a risk of pneumothorax steroids if hypoxic (if pO2 < 9.3kPa then steroids reduce risk of respiratory failure by 50% and death by a third)

Answer 7

GRAM POSITIVE RODS - Actinomyces - Bacillus anthracis (anthrax) - Clostridium - Diphtheria: Corynebacterium diphtheriae - Listeria monocytogenes GRAM NEGATIVE RODS Escherichia coli Haemophilus influenzae Pseudomonas aeruginosa Salmonella sp. Shigella sp. Campylobacter jejuni

Answer 8

Schistosoma haematobium Hosted by snails, which release cercariae that penetrate skin. Causes 'swimmer's itch' - frequency, haematuria. - Risk factor for squamous cell bladder cancer - Praziquantel

Answer 9

- The most common organism overall is Staphylococcus aureus. -The BNF currently recommends flucloxacillin or clindamycin if penicillin allergic.

Answer 10

Strongyloides stercoralis is a human parasitic nematode worm. The larvae are present in soil and gain access to the body by penetrating the skin. Infection with Strongyloides stercoralis causes strongyloidiasis. Features - Diarrhoea - Abdominal pain/bloating - Papulovesicular lesions where the skin has been penetrated by infective larvae e.g. soles of feet and buttocks larva currens: pruritic, linear, urticarial rash If the larvae migrate to the lungs a pneumonitis similar to Loeffler's syndrome may be triggered Treatment - Ivermectin and albendazole are used.

Answer 11

Infestation with threadworms (Enterobius vermicularis, sometimes called pinworms) is extremely common amongst children in the UK. Infestation occurs after swallowing eggs that are present in the environment. Threadworm infestation is asymptomatic in around 90% of cases, possible features include: perianal itching, particularly at night girls may have vulval symptoms Diagnosis may be made by the applying Sellotape to the perianal area and sending it to the laboratory for microscopy to see the eggs. However, most patients are treated empirically and this approach is supported in the CKS guidelines. Management CKS recommend a combination of anthelmintic with hygiene measures for all members of the household mebendazole is used first-line for children > 6 months old. A single dose is given unless infestation persists

Answer 12

Non-pregnant women local antibiotic guidelines should be followed if available NICE recommends trimethoprim or nitrofurantoin for 3 days send a urine culture if: aged > 65 years visible or non-visible haematuria Pregnant women if the pregnant woman is symptomatic: a urine culture should be sent in all cases should be treated with an antibiotic for 7 days first-line: nitrofurantoin (should be avoided near term) second-line: amoxicillin or cefalexin trimethoprim is teratogenic in the first trimester and should be avoided during pregnancy

Answer 13

Alphavirus disease caused by infected mosquitoes. Areas affected are Africa, Asia and Indian subcontinent but in recent years there has been seen in a few cases in Southern Europe. Tanzania had the first reported case. Symptoms: Prominent symptoms are severe joint pain and abrupt onset of high fever. Other symptoms include general flu-like illness of muscle ache, headache, and fatigue. The disease shares its symptoms with dengue but tends to have more joint pain which can be debilitating. A rash may develop as with other viral illness and swelling of the joints in not uncommon. Treatment: Relief of symptoms. No specific treatment.

Answer 14

Management of chickenpox exposure in pregnancy, i.e. post-exposure prophylaxis (PEP) if there is any doubt about the mother previously having chickenpox maternal blood should be urgently checked for varicella antibodies historically, exposure has been managed through the timely administration of varicella zoster immunoglobulin (VZIG). However, the guidance has changed due to a national/international VZIG shortage. This was initially a short-term deviation from practice in 2022 but has now become baked into longer-term guidance oral aciclovir (or valaciclovir) is now the first choice of PEP for pregnant women at any stage of pregnancy antivirals should be given at day 7 to day 14 after exposure, not immediately why wait until days 7-14? From the PHE guidelines: 'In a study evaluating the comparative effectiveness of 7 days course of aciclovir given either immediately after exposure or starting at day 7 after exposure to healthy children, the incidence and severity of varicella infection was significantly higher in those given aciclovir immediately (10/13 (77%) who received aciclovir immediately developed clinical varicella compared with 3/14 (21%) who started aciclovir at day 7)' Management of chickenpox in pregnancy if a pregnant woman develops chickenpox in pregnancy then specialist advice should be sought there is an increased risk of serious chickenpox infection (i.e. maternal risk) and fetal varicella risk (i.e. fetal risk) balanced against theoretical concerns about the safety of aciclovir in pregnancy Consensus guidelines (Health Protection Authority and RCOG) suggest oral aciclovir should be given if the pregnant woman is ≥ 20 weeks and she presents within 24 hours of the onset of the rash. if the woman is < 20 weeks the aciclovir should be 'considered with caution.

Answer 15

Leprosy is a granulomatous disease primarily affecting the peripheral nerves and skin. It is caused by Mycobacterium leprae. Features patches of hypopigmented skin typically affecting the buttocks, face, and extensor surfaces of limbs sensory loss The degree of cell mediated immunity determines the type of leprosy a patient will develop. Low degree of cell mediated immunity → lepromatous leprosy ('multibacillary') extensive skin involvement symmetrical nerve involvement High degree of cell mediated immunity → tuberculoid leprosy ('paucibacillary') limited skin disease asymmetric nerve involvement → hypesthesia hair loss Management WHO-recommended triple therapy: Rifampicin, dapsone, and clofazimine. ( RDC)

Answer 16

>>HIV antibody Enzyme-linked immunosorbent assays (ELISAs) are often used for screening.Western blot was previously used as a confirmation test but HIV-1/HIV-2 differentiation assays are now more commonly used most people develop antibodies to HIV at 4-6 weeks but 99% do by 3 months. >>HIV antibody and HIV antigen often referred to as 'fourth-generation' tests p24 antigen can be detected as early as 2-3 weeks after exposure the sensitivity of these fourth-generation tests approaches 100% for patients with chronic HIV infection now the first-line test for HIV screening of asymptomatic individuals or patients with signs and symptoms of chronic infection. >>HIV RNA (qualitative or quantitative) not routinely used for screening/testing however, may be useful for the diagnosis of neonatal HIV infection and screening blood donors.

Answer 17

Pneumocystis jirovecii pneumonia most likely on a background of undiagnosed HIV infection. Treatment for pneumocystis pneumonia is with oral co-trimoxazole or IV pentamidine if oral antibiotics or not tolerated. Steroids are also given if there is severe hypoxaemia

Answer 18

There are two strains of the herpes simplex virus (HSV) in humans: HSV-1 and HSV-2. Whilst it was previously thought HSV-1 accounted for oral lesions (cold sores) and HSV-2 for genital herpes it is now known there is considerable overlap Features primary infection: may present with a severe gingivostomatitis cold sores painful genital ulceration Management gingivostomatitis: oral aciclovir, chlorhexidine mouthwash cold sores: topical aciclovir although the evidence base for this is modest genital herpes: oral aciclovir. Some patients with frequent exacerbations may benefit from longer term aciclovir Pregnancy elective caesarean section at term is advised if a primary attack of herpes occurs during pregnancy at greater than 28 weeks gestation women with recurrent herpes who are pregnant should be treated with suppressive therapy and be advised that the risk of transmission to their baby is low

Answer 19

Visceral leishmaniasis (kala-azar) mostly caused by Leishmania donovani occurs in the Mediterranean, Asia, South America, Africa fever, sweats, rigors massive splenomegaly. hepatomegaly poor appetite*, weight loss occasionally patients may report increased appetite with paradoxical weight loss grey skin - 'kala-azar' means black sickness pancytopaenia secondary to hypersplenism the gold standard for diagnosis is bone marrow or splenic aspirate management the BNF recommends sodium stibogluconate, an organic pentavalent antimony compound amphotericin B may be used with or after treatment with an antimony compound

Answer 20

Tetanus is caused by the tetanospasmin exotoxin released from Clostridium tetani. Tetanus spores are present in soil and may be introduced into the body from a wound, which is often unnoticed. Tetanospasmin prevents the release of GABA, In developed countries, tetanus may be seen in intravenous drug users. Features - Prodrome fever, lethargy, headache trismus (lockjaw) - Risus sardonicus: facial spasms opisthotonus (arched back, - Hyperextended neck) spasms (e.g. dysphagia) Management Supportive therapy including ventilatory support and muscle relaxants Intramuscular human tetanus immunoglobulin for high-risk wounds (e.g. compound fractures, delayed surgical intervention, significant degree of devitalised tissue) - Metronidazole is now preferred to benzylpenicillin as the antibiotic of choice

Answer 21

3 months of isoniazid (with pyridoxine) and rifampicin OR 6 months of isoniazid (with pyridoxine)

Answer 22

- Nitazoxanide may be used to treat immunocompromised patients with cryptosporidiosis. - Diagnosis stool: modified Ziehl-Neelsen stain (acid-fast stain) of the stool may reveal the characteristic red cysts of Cryptosporidium

Answer 23

Virus Change of transmission Hepatitis B 20-30% Hepatitis C 0.5-2% HIV 0.3%

Answer 24

The viral load determines the risk of HIV transmission following a needle stick injury

Answer 25

Normal pO2 but decreased oxygen saturation is characteristic of methaemoglobinaemia

Answer 26

Escherichia coli is a facultative anaerobic, lactose-fermenting, Gram negative rod which is a normal gut commensal. E. coli infections lead to a variety of diseases in humans including: - diarrhoeal illnesses - UTIs - neonatal meningitis

Answer 27

- Gram-negative bacillus Campylobacter jejuni. - Campylobacter infection is characterised by a prodrome, abdominal pain and bloody diarrhoea. - the first-line antibiotic is clarithromycin. Complications Guillain-Barre syndrome reactive arthritis septicaemia, endocarditis, arthritis

Answer 28

Nucleoside analogue reverse transcriptase inhibitors (NRTI) examples: zidovudine (AZT), abacavir, emtricitabine, didanosine, lamivudine, stavudine, zalcitabine, tenofovir general NRTI side-effects: peripheral neuropathy tenofovir: used in BHIVAs two recommended regime NRTI. Adverse effects include renal impairment and ostesoporosis zidovudine: anaemia, myopathy, black nails didanosine: pancreatitis Non-nucleoside reverse transcriptase inhibitors (NNRTI) examples: nevirapine, efavirenz side-effects: P450 enzyme interaction (nevirapine induces), rashes Protease inhibitors (PI) examples: indinavir, nelfinavir, ritonavir, saquinavir side-effects: diabetes, hyperlipidaemia, buffalo hump, central obesity, P450 enzyme inhibition indinavir: renal stones, asymptomatic hyperbilirubinaemia ritonavir: a potent inhibitor of the P450 system Integrase inhibitors block the action of integrase, a viral enzyme that inserts the viral genome into the DNA of the host cell examples: raltegravir, elvitegravir, dolutegravir

Answer 29

Tetanus toxin (tetanospasmin) blocks the release of the inhibitory neurotransmitters GABA and glycine, resulting in continuous motor neuron activity.

Answer 30

False negative tests may be caused by: - miliary TB - sarcoidosis - HIV - lymphoma - very young age (e.g. < 6 months)

Answer 31

Management - Doxycycline (7-day course) if first-line - If pregnant, then azithromycin, erythromycin, or amoxicillin may be used. The SIGN guidelines suggest that azithromycin 1g stat is the drug of choice.

Answer 32

Ivermectin and albendazole are used

Answer 33

Carriage of pneumococcus is extremely common and no antibiotic prophylaxis is generally required.

Answer 34

Features vaginal discharge: 'fishy', offensive asymptomatic in 50% Amsel's criteria for diagnosis of BV - 3 of the following 4 points should be present thin, white homogenous discharge clue cells on microscopy: stippled vaginal epithelial cells vaginal pH > 4.5 positive whiff test (addition of potassium hydroxide results in fishy odour)

Answer 35

Hydatid cysts are endemic in Mediterranean and Middle Eastern countries. They are caused by the tapeworm parasite Echinococcus granulosus. An outer fibrous capsule is formed containing multiple small daughter cysts. These cysts are allergens that precipitate a type 1 hypersensitivity reaction. -Surgery is the mainstay of treatment

Answer 36

C5-9 deficiency predisposes to Neisseria meningitidis infections.

Answer 37

C1 inhibitor (C1-INH) protein deficiency causes hereditary angioedema C1-INH is a multifunctional serine protease inhibitor probable mechanism is uncontrolled release of bradykinin resulting in oedema of tissues C1q, C1rs, C2, C4 deficiency (classical pathway components) predisposes to immune complex disease e.g. SLE, Henoch-Schonlein Purpura C3 deficiency causes recurrent bacterial infections C5 deficiency predisposes to Leiner disease recurrent diarrhoea, wasting and seborrhoeic dermatitis C5-9 deficiency encodes the membrane attack complex (MAC) particularly prone to Neisseria meningitidis infection

Answer 38

Measles is characterised by prodromal symptoms, Koplik spots. maculopapular rash starting behind the ears and conjunctivitis.

Answer 39

Blisters/bullae no mucosal involvement (in exams at least*): bullous pemphigoid mucosal involvement: pemphigus vulgaris

Answer 40

Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230. Bullous pemphigoid is more common in elderly patients. Features include itchy, tense blisters typically around flexures The blisters usually heal without scarring There is stereotypically no mucosal involvement (i.e., the mouth is spared

Answer 41

Skin biopsy Immunofluorescence shows IgG and C3 at the dermoepidermal junction

Answer 42

Ivermectin and albendazole are used

Answer 43

Benzylpenicillin

Answer 44

- Ceftriaxone 500mg intramuscularly single dose, plus doxycycline 100mg by mouth twice daily for 10-14 days

Answer 45

Pathophysiology - HSV-1 is responsible for 95% of cases in adults - Typically affects temporal and inferior frontal lobes Investigation - CSF: lymphocytosis, elevated protein - PCR for HSV - CT: medial temporal and inferior frontal changes (e.g. petechial haemorrhages) - normal in one-third of patients - MRI is better - EEG pattern: lateralised periodic discharges at 2 Hz Treatment - Intravenous aciclovir

Answer 46

Live vaccines given by injection may be either given concomitantly or a minimum interval of 4 weeks apart to prevent risk of immunological interference

Answer 47

examples: BCG measles, mumps, rubella (MMR) influenza (intranasal) oral rotavirus oral polio yellow fever oral typhoid

Answer 48

Plasmodium vivax/ovale: cyclical fever every 48 hours. Plasmodium malariae: cyclical fever every 72 hours Plasmodium malariae: is associated with nephrotic syndrome. Ovale and vivax malaria have a hypnozoite stage and may therefore relapse following treatment. Treatment in areas which are known to be chloroquine-sensitive then WHO recommend either an artemisinin-based combination therapy (ACT) or chloroquine in areas which are known to be chloroquine-resistant an ACT should be used ACTs should be avoided in pregnant women patients with ovale or vivax malaria should be given primaquine following acute treatment with chloroquine to destroy liver hypnozoites and prevent relapse

Answer 49

P. knowlesi has the shortest erythrocytic replication cycle, leading to high parasite counts in short periods of time.

Answer 50

Primaquine is used in non-falciparum malaria to destroy liver hypnozoites and prevent relapse

Answer 51

Lassa fever is contracted by contact with the excreta of infected African rats (Mastomys rodent)

Answer 52

Examples of viral haemorrhagic fever (VHF) include: Flaviviridae: dengue, yellow fever Arenaviridae: Lassa fever Filoviridae: Ebola virus, Marburg virus Bunyaviridae: Hantaviruses, Crimean-Congo haemorrhagic fever, Rift Valley fever

Answer 53

Amoxicillin is an alternative to treat early Lyme disease if doxycycline is contraindicated such as in pregnancy

Answer 54

Genital wart treatment multiple, non-keratinised warts: topical podophyllum solitary, keratinised warts: cryotherapy

Answer 55

Familial Mediterranean Fever (FMF, also known as recurrent polyserositis) is an autosomal recessive disorder that typically presents by the second decade. It is more common in people of Turkish, Armenian, and Arabic descent. Features - attacks typically last 1-3 days pyrexia abdominal pain (due to peritonitis) pleurisy pericarditis arthritis erysipeloid rash on lower limbs Management colchicine may help

Answer 56

Infectious mononucleosis (glandular fever) is caused by the Epstein-Barr virus (EBV, also known as human herpesvirus 4, HHV-4) in 90% of cases. Less frequent causes include cytomegalovirus and HHV-6. It is most common in adolescents and young adults. The classic triad of sore throat, pyrexia and lymphadenopathy is seen in around 98% of patients. -Diagnosis heterophil antibody test (Monospot test)

Answer 57

Malaise, anorexia, headache palatal petechiae Splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture hepatitis, transient rise in ALT Lymphocytosis: presence of 50% lymphocytes with at least 10% atypical lymphocytes haemolytic anaemia secondary to cold agglutins (IgM) A maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis

Answer 58

Criteria for severe falciparum malaria High parasitaemia (>2%) Hypoglycaemia Severe anaemia Renal failure Pulmonary oedema Metabolic acidosis Abnormal bleeding Multiple convulsions Seizures Shock Management Severe falciparum, malaria IV artesunate Non-severe falciparum malaria oral artesunate combination therapy (ACT) Non-falciparum malaria oral ACT or chloroquine if not resistant

Answer 59

-atovaquone + proguanil (Malarone) - Chloroquine is safe in pregnancy

Infectious diseases Flashcards

(87 cards)