Microbiology Flashcards

Question

Which antibiotics have beta-lactam rings vs w/o

Answer 1

Antibiotics with a beta-lactam ring: Penicillin Carbapenems such as meropenem Cephalosporins Antibiotics without a beta-lactam ring: Vancomycin Teicoplanin

Answer 2

Co-trimoxazole

Answer 3

Start with amoxicillin which covers streptococcus, listeria and enterococcus Switch to co-amoxiclav to additionally cover staphylococcus, haemophilus and e. coli Switch to tazocin to additionally cover pseudomonas Switch to meropenem to additionally cover ESBLs Add teicoplanin or vancomycin to cover MRSA Add clarithromycin or doxycycline to cover atypical bacteria

Answer 4

Co-amoxiclav and Doxycycline

Answer 5

Gram positive bacteria such as Streptococcus, listeria and enterococcus

Answer 6

Gram positive and atypical bacteria

Answer 7

Gram positive and Anaerobe

Answer 8

Gram negative

Answer 9

Gram negative and Atypical

Answer 10

Gram positive resistant e.g. MRSA

Answer 11

Linezolid and daptomycin

Answer 12

Cytokines such as interleukins and tumor necrosis factor

Answer 13

Release of nitrous oxide which causes vasodilation

Answer 14

cytokines cause the endothelial lining of blood vessels to become more permeable. This causes fluid to leak out of the blood and in to the extracellular space leading to oedema and a reduction in intravascular volume. The oedema around blood vessels creates a space between the blood and the tissues reducing the amount of oxygen that reaches the tissues. Activation of the coagulation system leads to deposition of fibrin throughout the circulation further compromising organ and tissue perfusion. It also leads to consumption of platelets and clotting factors as they are being used up to form the clots within the circulatory system. This leads to thrombocytopenia, haemorrhages and an inability to form clots and stop bleeding. This is called disseminated intravascular coagulopathy (DIC). Blood lactate rises due to hypoperfusion of tissues that starves the tissues of oxygen causing them to switch to anaerobic respiration. A waste product of anaerobic respiration is lactate

Answer 15

Systolic BP: less than 90 despite fluid resuscitation Hyperlactaemia: (lactate > 4 mmol/L)

Answer 16

This should be treated aggressively with IV fluids to improve the blood pressure and the tissue perfusion. If IV fluid boluses don’t improve the blood pressure and lactate level then they should be escalated to high dependency or intensive care where they can use medication called inotropes (such as noradrenalin) that help stimulate the cardiovascular system and improve blood pressure and tissue perfusion.

Answer 17

Severe sepsis is defined when sepsis is present and results in organ dysfunction, for example: Hypoxia Oliguria Acute Kidney Injury Thrombocytopenia Coagulation dysfunction Hypotension Hyperlactaemia (> 2 mmol/L)

Answer 18

Any condition that impacts the immune system or makes the patient more frail or prone to infection is a risk factor for developing sepsis: Very young or old patients (under 1 or over 75 years) Chronic conditions such as COPD and diabetes Chemotherapy, immunosuppressants or steroids Surgery or recent trauma or burns Pregnancy or peripartum Indwelling medical devices such as catheters or central lines

Answer 19

The National Early Warning Score (NEWS) is used in the UK to pick up the signs of sepsis. This involves checking physical observations and their consciousness level: Temperature Heart rate Respiratory rate Oxygen saturations Blood pressure Consciousness level Other signs on examination: Signs of potential sources such as cellulitis, discharge from a wound, cough or dysuria Non-blanching rash can indicate meningococcal septicaemia Reduced urine output Mottled skin Cyanosis Arrhythmias such as new onset atrial fibrillation There are a few key points worth being aware of: High respiratory rate (tachypnoea) is often the first sign of sepsis Elderly patients often present with confusion or drowsiness or simply “off legs” Neutropenic or immunosuppressed patients may have normal observations and temperature despite being life threatening unwell

Answer 20

Arrange blood tests for patients with suspected sepsis: - Full blood count to assess cell count including white cells and neutrophils - U&Es to assess kidney function and for acute kidney injury - LFTs to assess liver function and for possible source of infection - CRP to assess inflammation - Clotting to assess for disseminated intravascular coagulopathy (DIC) - Blood cultures to assess for bacteraemia - Blood gas to assess lactate, pH and glucose Additional investigations can be helpful in locating the source of the infection: Urine dipstick and culture - Chest xray - CT scan if intra-abdominal infection or abscess is suspected - Lumbar puncture for meningitis or encephalitis

Answer 21

Three Tests: - Blood lactate level - Blood cultures - Urine output Three Treatments: - Oxygen to maintain oxygen saturations 94-98% (or 88-92% in COPD) - Empirical broad spectrum antibiotics - IV fluids

Answer 22

Neutropenic sepsis is a very important medical emergency. It is sepsis in a patient with a low neutrophil count of less than 1 x 109/L.

Answer 23

Anti-cancer chemotherapy Clozapine (schizophrenia) Hydroxychloroquine (rheumatoid arthritis) Methotrexate (rheumatoid arthritis) Sulfasalazine (rheumatoid arthritis) Carbimazole (hyperthyroidism) Quinine (malaria) Infliximab (monoclonal antibody use for immunosuppression) Rituximab (monoclonal antibody use for immunosuppression)

Answer 24

Broad spectrum antibiotic e.g. Tazocin

Answer 25

cough and sputum production, shortness of breath, fever, lethargy and crackles on the chest

Answer 26

Productive cough

Answer 27

Streptococcus pneumoniae (50%) Haemophilus influenzae (20%)

Answer 28

- Moraxella catarrhalis in immunocompromised patients or those with chronic pulmonary disease - Pseudomonas aeruginosa in patients with cystic fibrosis or bronchiectasis - Staphylococcus aureus in patients with cystic fibrosis

Answer 29

Legions – Legionella pneumophila Psittaci – Chlamydia psittaci M – Mycoplasma pneumoniae C – Chlamydydophila pneumoniae Qs – Q fever (coxiella burnetii)

Answer 30

Amoxicillin

Answer 31

Eruthromycin/clarithromycin or Doxycycline

Answer 32

Macrolides such as clarithromycin Quinolones such as levofloxacin Tetracycline such as doxycycline

Answer 33

Sexual activity spreading faecal matter around the perineum, hygiene problems and urinary catherters (harder to trear)

Answer 34

- Dysuria (pain, stinging or burning when passing urine) - Suprapubic pain or discomfort - Frequency - Urgency - Incontinence - Confusion is commonly the only symptom in older more frail patients

Answer 35

- Fever is a more prominent feature than lower urinary tract infections. - Loin, suprapubic or back pain. This may be bilateral or unilateral. - Looking and feeling generally unwell - Vomiting - Loss of appetite - Haematuria - Renal angle tenderness on examination

Answer 36

Nitrites and Leukocyte esterase

Answer 37

Gram negative bacteria (such as E. coli) breakdown nitrates, a normal waste product in urine, into nitrites. The presence of nitrites suggest bacteria presence

Answer 38

Nitrites are a better indication of infection than leukocytes. If both are present then the patient should be treated as a UTI. If only nitrites are present then it is worth treating as a UTI however if only leukocytes are present then the patient should not be treated as a UTI unless there is clinical evidence that they have a UTI. If nitrites or leukocytes are present the urine should be sent to the microbiology lab. If neither are present the patient is unlikely to have a UTI

Answer 39

- Klebsiella pneumoniae (gram-negative anaerobic rod) - Enterococcus - Pseudomonas aeruginosa - Staphylococcus saprophyticus - Candida albicans (fungal)

Answer 40

- 3 days of antibiotics for a simple lower urinary tract infection in women - 5-10 days of antibiotics for women that are immunosuppressed, have abnormal anatomy or impaired kidney function - 7 days of antibiotics for men, pregnant women or catheter related UTIs

Answer 41

Trimethroprim or Nitrofurantoin

Answer 42

Pivmecillinam, Amoxicillin, Cefalexin

Answer 43

Avoid in third trimester of pregnancy as linked with haemolytic anaemia

Answer 44

Referral to hospital if there are features of sepsis. NICE recommend the following first line antibiotics for 7-10 days when treating pyelonephritis in the community: Cefalexin Co-amoxiclav Trimethoprim Ciprofloxacin

Answer 45

Acute diverticulitis Cholecystitis (with secondary infection) Ascending cholangitis Appendicitis Spontaneous bacterial peritonitis Intra-abdominal abscess

Answer 46

- Anaerobes (e.g. bacteroides and clostridium) - E. coli - Klebsiella - Enterococcus - Streptococcus

Answer 47

Broad-spectrum antibiotic such as Co-Amoxiclav

Answer 48

Co-amoxiclav - good for gram positive, gram negative and anaerobic. Does not cover pseudomonas or atypical bacteria Quinolones - Ciprofloxacin and Levofloxacin provide reasonable Gram neg and pos cover and also cover atypical but don't cover anaerobes so is usually paired with metronidazole Metronidazole - Exceptional anaerobic coverage but no cover against aerobic Gentamicin - Good gram negative cover with some gram positive cover (particularly against staph) and its bactericidal Vancomycin - V good gram positive cover including MRSA, often combined with Gentamicin to cover gram negatives and metronidazole to cover anaerobes in patients with Penicillin allergies Cephalosporins - Good broad spectrum cover against gram positive and gram negative but not v effective against anaerobes - avoided due to risk of C.diff infection Tazocin/Meropenem - heavy hitters that cover gram positive, negative and anerobes. They don't cover atypical or MRSA and tazocin doesnt cover ESBL's but covers almost everything else - usuallt reserved for very unwell patients that are not responding to other antibiotics

Answer 49

- Co-amoxiclav alone - Amoxicillin plus gentamicin plus metronidazole - Ciprofloxacin plus metronidazole (penicillin allergy) - Vancomycin plus gentamicin plus metronidazole (penicillin allergy)

Answer 50

A stat dose of gentamicin is often added to regimes not including gentamicin if the patient is severely septic to provide initial strong bactericidal gram negative action.

Answer 51

- Piperacillin/Tazobactam (Tazocin) is often first line - Cephalosporins such as cefotaxime are also often used - Levofloxacin plus metronidazole is an common alternative in penicillin allergy

Answer 52

Septic arthritis is where an infection occurs within a joint

Answer 53

- Hot, red, swollen and painful joint - Stiffness and reduced range of motion - Systemic symptoms such as fever, lethargy and sepsis

Answer 54

Staph aureus

Answer 55

- Neisseria gonorrhoea (gonococcus) in sexually active individuals - Group A Streptococcus (most commonly Streptococcus pyogenes) - Haemophilus influenza - Escherichia coli (E. coli)

Answer 56

- **Gout** (fluid shows urate crystals that are negatively birefringent of polarised light) - **Pseudogout** (fluid shows calcium pyrophosphate crystals that are rod-shaped intracellular crystals positively birefringent of polarised light) - **Reactive arthritis** typically triggered by urethritis or gastroenteritis and associated with conjunctivitis - **Haemarthrosis** (bleeding into the joint)

Answer 57

Have a low threshold for treatment Aspirate the joint prior to antibiotics and send the sample for gram staining, crystal microscopy, culture and antibiotic sensitivities. The joint fluid may be purulent (full of pus). The gram stain will come back quite quickly and may give a clue about the organism. The full culture will take longer Empirical IV antibiotics should be given until the sensitivities are known. Antibiotics are usually continued for 3 – 6 weeks in total. Choice of antibiotic depends on the local guidelines. Example regimes are: - Flucloxacillin plus rifampicin is often first line - Vancomycin plus rifampicin for penicillin allergy, MRSA or prosthetic joint - Clindamycin is an alternative

Answer 58

The influenza virus is an RNA virus. There are three types: A, B and C, of which A and B are the most common. The A type has different H and N subtypes and you may hear about different strains, for example H1N1 (swine flu) and H5N1 (avian flu). Outbreaks typically occur during the winter

Answer 59

- Fever - Coryzal symptoms - Lethargy and fatigue - Anorexia (loss of appetite) - Muscle and joint aches - Headache - Dry cough - Sore throat

Answer 60

Treatment is usually started based on the history, risk factors and clinical presentation. Viral nasal or throat swabs can be sent to the local virology lab for polymerase chain reaction (PCR) analysis. This will confirm the diagnosis and also provide data to public health so that they can monitor the number of cases of influenza

Answer 61

- Oral oseltamivir 75mg twice daily for 5 days - Inhaled zanamivir 10mg twice daily for 5 days Treatment needs to be started within 48 hours of the onset of symptoms to be effective. Post-exposure prophylaxis can be given to higher risk patients such as those with chronic diseases or immunosuppression within 48 hours of close contact with influenza. This aims to minimise the risk of developing flu and complications. - Oral oseltamivir 75mg once daily for 10 days - Inhaled zanamivir 10mg once daily for 10 days

Answer 62

Otitis media, sinusitis and bronchitis Viral pneumonia Secondary bacteria pneumonia Worsening of chronic health conditions such as COPD and heart failure Febrile convulsions (young children) Encephalitis

Answer 63

Acute gastritis is inflammation of the stomach and presents with nausea and vomiting. Enteritis is inflammation of the intestines and presents with diarrhoea. Gastroenteritis is inflammation all the way from the stomach to the intestines and presents with nausea, vomiting and diarrhoea.

Answer 64

- Rotavirus - Norovirus - Adenovirus is a less common cause and presents with a more subacute diarrhoea

Answer 65

Produces Shiga toxin which causes abdo cramps, bloody diarrhoea and vomiting and it destroys blood cells leading to HUS

Answer 66

Raw or improperly cooked poultry, Untreated water and unpasteurised milk

Answer 67

Abdominal cramps Diarrhoea often with blood Vomiting Fever

Answer 68

Azithromycin and Ciprofloxacin

Answer 69

Shigella is spread by faeces contaminating drinking water, swimming pools and food. The incubation period is 1-2 days and symptoms usually resolve within 1 week without treatment. It causes bloody diarrhoea, abdominal cramps and fever. Shigella can produce the Shiga toxin and cause haemolytic uraemic syndrome. Treatment of severe cases is with azithromycin or ciprofloxacin

Answer 70

Salmonella is spread by eating raw eggs or poultry and food contaminated with infected faeces of small animals. Incubation is 12 hours to 3 days and symptoms usually resolve within 1 week. Symptoms are watery diarrhoea that can be associated with mucus or blood, abdominal pain and vomiting. Antibiotics are only necessary in severe cases and guided by stool culture and sensitivities.

Answer 71

Bacillus cereus is a gram positive rod that is spread through inadequately cooked food. It grows well on food not immediately refrigerated after cooking. The typical food is fried rice left out at room temperature. Whilst growing on the food it produces a toxin called cereulide that causes abdominal cramping and vomiting within 5 hours of ingestion. When it arrives in the intestines it produces different toxins that cause a watery diarrhoea. This occurs more than 8 hours after ingestion. All of the symptoms usually resolves within 24 hours. Therefore the typical course is vomiting within 5 hours, then diarrhoea after 8 hours, then resolution within 24 hours Typical exam presentation: Patient eats leftover fried rice

Answer 72

Yersinia is a **gram-negative bacillus**. Pigs are key carriers of Yersinia and eating raw or undercooked pork can cause infection. It is also spread through contamination with the urine or faeces of other mammal such as rat and rabbits. Yersinia most frequently affects children causing watery or bloody diarrhoea, abdominal pain, fever and **lymphadenopathy**. Incubation is 4-7 days and the illness can last longer than other causes of enteritis with symptoms lasting 3 weeks or more. Older children or adults can present with right-sided abdominal pain due to **mesenteric lymphadenitis** (inflammation in the intestinal lymph nodes) and fever which can give the impression of **appendicitis**. Antibiotics are only necessary in severe cases and guided by stool culture and sensitivities.

Answer 73

Giardia lamblia is a type of microscopic parasite. It lives in the small intestines of mammals. These mammals may be pets, farmyard animals or humans. It releases cysts in the stools of infected mammals. These cysts then contaminate food or water and are eaten to infect a new host. This is called faecal-oral transmission. Infection may not cause any symptoms or it may cause chronic diarrhoea. Diagnosis is made by stool microscopy. Treatment is with metronidazole.

Answer 74

Good hygiene, immediately isolate patient to prevent spread, test faeces with microscopy, culture and sensitivities to establish cause, attempt a fluid challenge to see if they can tolerate oral fluid and then give rehydration solutions (e.g. dioralyte), slowly introduce light diet in small quantities once oral intake is tolerated, antibiotics only used in patients at risk of complications and once causative organism is found

Answer 75

- Lactose intolerance - Irritable bowel syndrome - Reactive arthritis - Guillain–Barré syndrome

Answer 76

Neisseria meningitidis is a gram negative diploccous bacteria. They are circular bacteria (“-cocci”) that occur in pairs (“diplo-”). It is commonly known as meningococcus

Answer 77

Meningococcal septicaemia is when the meningococcus bacterial infection is in the bloodstream Meningococcal septicaemia is the cause of the classic “non-blanching rash” that everybody worries about as it indicates the infection has caused disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages

Answer 78

Meningococcal meningitis is when the bacteria is infecting the meninges and the cerebrospinal fluid around the brain and spinal cord

Answer 79

Streptococcus pneumoniae (pneumococcus). In neonates the most common cause is Group B Streptococcus (GBS). GBS is usually contracted during birth from the GBS bacteria that can often live harmlessly in the mothers vagina

Answer 80

Typical symptoms of meningitis are fever, neck stiffness, vomiting, headache, photophobia, altered consciousness and seizures. Where there is meningococcal septicaemia children can present with a non-blanching rash. Other causes of bacterial meningitis do not usually cause the non-blanching rash

Answer 81

**Kernig’s test** involves lying the patient on their back, flexing one hip and knee to 90 degrees and then slowly straightening the knee whilst keeping the hip flexed at 90 degrees. This creates a slight stretch in the meninges and where there is meningitis will produce spinal pain or resistance to this movement. **Brudzinski’s** test involves lying the patient flat on their back and gently using your hands to lift their head and neck off the bed and flex their chin to their chest. A positive test is when this causes the patient to involuntarily flex their hips and knees.

Answer 82

Meningococcal septicaemia and bacterial meningitis are medical emergencies and should be treated immediately. Community Children seen in the primary care setting with suspected meningitis AND a non blanching rash should receive an urgent stat injection (IM or IV) of **benzylpenicillin** prior to transfer to hospital as time is so important: < 1 year – 300mg 1-9 years – 600mg > 10 years and adults – 1200mg This shouldn’t delay transfer. Where there is a true penicillin allergy transfer should be the priority rather than other antibiotics.

Answer 83

Ideally a blood culture and a lumbar puncture for cerebrospinal fluid (CSF) should be performed prior to starting antibiotics however if the patient is acutely unwell antibiotics should not be delayed. Send blood tests for meningococcal PCR if meningococcal disease is suspected. This tests directly for the meningococcal DNA. It can give a result quicker than blood culture depending on local services and will still be positive after the bacteria has been treated with antibiotics.

Answer 84

< 3 months – **cefotaxime plus amoxicillin** (the amoxicillin is to cover listeria contracted during pregnancy from the mother) > 3 months – **ceftriaxone** Add Vancomycin if theres a risk of penicillin resistant infection Steroids are used to reduce frequency and severity of hearing loss and neurological damage. Dexamethasone is given 4 times daily for 4 days to children over 3 months Inform public healt

Answer 85

< 3 months – **cefotaxime plus amoxicillin** (the amoxicillin is to cover listeria contracted during pregnancy from the mother) > 3 months – **ceftriaxone** Add Vancomycin if theres a risk of penicillin resistant infection Steroids are used to reduce frequency and severity of hearing loss and neurological damage. Dexamethasone is given 4 times daily for 4 days to children over 3 months Inform public health

Answer 86

The most common causes of viral meningitis are herpes simplex virus (HSV), enterovirus and varicella zoster virus (VZV). A sample of the CSF from the lumbar puncture should be sent for viral PCR testing.

Answer 87

Viral meningitis tends to be milder than bacterial and often only requires supportive treatment. **Aciclovir** can be used to treat suspected or confirmed HSV meningitis.

Answer 88

- Hearing loss is a key complication - Seizures and epilepsy - Cognitive impairment and learning disability - Memory loss - Focal neurological deficits such as limb weakness or spasticity

Answer 89

**Mycobacterium Tuberculosis**. It is a small **rod shaped** bacteria (a bacillus). It has a waxy coating that makes gram staining ineffective. They are resistant to the acids used in the staining procedure. This property is called **acid-fastness**. Therefore, the TB bacteria are described as **acid-fast bacilli**. They require a special staining technique using the **Zeihl-Neelsen stain**. This turns TB bacteria **bright red** against a blue background.

Answer 90

TB is more prevalent in non-UK born patients (i.e. from South Asia), those who are immunocompromised (i.e. HIV) and those with close contacts with TB. Multi-Drug Resistant TB (MDR TB) are strains that are resistant to more than one TB drug making them very difficult to treat

Answer 91

The TB bacteria are very slow dividing with high oxygen demands and this makes them difficult to culture and treat. It is mostly spread by inhaling saliva droplets from infected people. It then spreads through the lymphatics and blood. Granulomas containing the bacteria form around the body

Answer 92

Active TB is where there is active infection in various areas within the body

Answer 93

The immune system may encapsulate sites of infection and stop the progression of the disease and this is referred to as latent TB

Answer 94

When latent TB reactivates this is known as secondary TB

Answer 95

When the immune system is unable to control the disease this causes a disseminated, severe disease and is referred to as miliary TB

Answer 96

- Lymph nodes. A “cold abscess” is a firm painless abscess caused by TB, usually in the neck. They do not have the inflammation, redness and pain you would expect from an acutely infected abscess. - Pleura - Central nervous system - Pericardium - Gastrointestinal system - Genitourinary system - Bones and joints - Cutaneous TB affecting the skin

Answer 97

Known contact with active TB Immigrants from areas of high TB prevalence People with relatives or close contacts from countries with a high rate of TB Immunosuppression due to conditions like HIV or immunosuppressant medications Homeless people, drug users or alcoholics

Answer 98

The BCG vaccine involves an intradermal infection of live attenuated (weakened) TB. It offers protection against severe and complicated TB but is less effective at protecting against pulmonary TB. Prior to the vaccine patients are tested with the Mantoux test and given the vaccine only if this test is negative. They are also assessed for the possibility of immunosuppression and HIV due to the risks related to a live vaccine. BCG vaccine is offered to patients that are at higher risk of contact with TB: - Neonates born in areas of the UK with high rates of TB - Neonates with relatives from countries with a high rate of TB - Neonates with a family history of TB - Unvaccinated older children and young adults (< 35) who have close contact with TB - Unvaccinated children or young adults that recently arrived from a country with a high rate of TB - Healthcare workers

Answer 99

Tuberculosis usually presents with a history of chronic, gradually worsening symptoms. Most cases are of pulmonary TB (around 70%) but they often have systemic symptoms. Typical signs and symptoms of TB include: - Lethargy - Fever or night sweats - Weight loss - Cough with or without haemoptysis - Lymphadenopathy - Erythema nodosum - Spinal pain in spinal TB (also known as Pott’s disease of the spine)

Answer 100

Tuberculosis can be very difficult to diagnose. The bacteria grows very slowly in a culture compared with other bacteria. It also can’t be stained with traditional gram stains and requires specialist stains like the Ziehl-Neelsen stain. There are two tests for an immune response to TB caused by previous, latent or active TB. These are the Mantoux test and interferon‑gamma release assay. In patients where the active disease is suspected a chest xray and cultures are used to support the diagnosis

Answer 101

The Mantoux test is used to look for a previous immune response to TB. This indicates possible previous vaccination, latent or active TB. This involves injecting tuberculin into the intradermal space on the forearm. Tuberculin is a collection of tuberculosis proteins that have been isolated from the bacteria. The infection does not contain any live bacteria. Injecting the tuberculin creates a bleb under the skin. After 72 hours the test is “read”. This involves measuring the induration of the skin at the site of the injection. NICE suggest considering an induration of 5mm or more a positive result. After a positive result they should be assessed for active disease.

Answer 102

This test involves taking a sample of blood and mixing it with antigens from the TB bacteria. In a person that has had previous contact with TB the white blood cells have become sensitised to those antigens and they will release interferon-gamma as part of an immune response. If interferon-gamma is released from the white blood cells then this is considered a positive result. The IGRA test is used in patients that do not have features of active TB but do have a positive Mantoux test to confirm a diagnosis of latent TB.

Answer 103

- **Primary TB** may show patchy consolidation, pleural effusions and hilar lymphadenopathy - **Reactivated TB** may show patchy or nodular consolidation with cavitation (gas filled spaces in the lungs) typically in the upper zones - **Disseminated Miliary TB** give a picture of “**millet seeds**” uniformly distributed throughout the lung fields

Answer 104

Otherwise healthy patients do not necessarily need treatment for latent TB. Patients at risk of reactivation of latent TB can be treated with either: Isoniazid and rifampicin for 3 months Isoniazid for 6 months

Answer 105

Management of active TB is coordinated by a specialist TB service with an MDT approach. **RIPE** is the mnemonic used to remember the treatment for TB. It involves a combination of 4 drugs used at the same time: R – Rifampicin for 6 months I – Isoniazid for 6 months P – Pyrazinamide for 2 months E – Ethambutol for 2 months

Answer 106

- Test for other infections - Test contact for TB - Notify Public health - Isolate patient - Specialist MDT management and follow up - Different drug regime for multidrug-resistant TB

Answer 107

- **Rifampicin** can cause red/orange discolouration of secretions like urine and tears. It is a potent inducer of cytochrome P450 enzymes therefore reduces the effect of drugs metabolised by this system. This is important for medications such as the contraceptive pill. - **Isoniazid** can cause peripheral neuropathy. Pyridoxine (vitamin B6) is usually co-prescribed prophylactically to reduce the risk of peripheral neuropathy. - **Pyrazinamide** can cause hyperuricaemia (high uric acid levels) resulting in gout. - **Ethambutol** can cause colour blindness and reduced visual acuity. - **Rifampicin, isoniazid and pyrazinamide** are all associated with hepatotoxicity

Answer 108

HIV – Human Immunodeficiency Virus AIDS – Acquired Immunodeficiency Syndrome AIDS is usually referred to in the UK as Late-Stage HIV

Answer 109

HIV is an **RNA retrovirus**. **HIV-1** is the most common type. **HIV-2** is rare outside West Africa. The virus enters and destroys the **CD4 T helper cells**. An initial **seroconversion** flu-like illness occurs within a few weeks of infection. The infection is then asymptomatic until it progresses and the patient becomes immunocompromised and develops **AIDS-defining illnesses** and opportunistic infections potentially years later.

Answer 110

HIV can’t spread through normal day to day activities including kissing. It is spread through: - Unprotected anal, vaginal or oral sexual activity. - Mother to child at any stage of pregnancy, birth or breastfeeding. This is referred to as vertical transmission. - Mucous membrane, blood or open wound exposure to infected blood or bodily fluids such as through sharing needles, needle-stick injuries or blood splashed in an eye.

Answer 111

There is a long list of **AIDS-defining illnesses** associated with **end-stage HIV** infection where the CD4 count has dropped to a level that allows for unusual opportunistic infections and malignancies to appear. Some examples are: - Kaposi’s sarcoma - Pneumocystis jirovecii pneumonia (PCP) - Cytomegalovirus infection - Candidiasis (oesophageal or bronchial) - Lymphomas - Tuberculosis

Answer 112

HIV is a treatable condition and most patients are fit and healthy on treatment. There are many people that have HIV that do not know the diagnosis and these patients are at risk of the complications and spreading the disease. Generally the earlier a patient is diagnosed the better the outcome. We should test practically everyone admitted to hospital with an infectious disease regardless of their risk factors. Patients with any risk factors should be tested. Antibody tests can be negative for 3 months following exposure so repeat testing is necessary if an initial test is negative within 3 months of a potential exposure. Patients need to give consent for a test. Verbal consent should be documented prior to a test. Consent only needs to be as simple as “are you happy for us to test you for HIV?” Patients no longer require formal counselling or education prior to a test.

Answer 113

p24 antigen

Answer 114

PCR testing

Answer 115

**CD4 count** This is a count of the number of CD4 cells in the blood. These are the cells destroyed by the HIV virus. The lower the count the higher the risk of opportunistic infection. 500-1200 cells/mm3 is the normal range Under 200 cells/mm3 is considered end stage HIV / AIDS and puts the patient at high risk of opportunistic infections **Viral Load (VL)** **Viral load** is the number of copies of HIV RNA per ml of blood. “Undetectable” refers to a viral load below the labs recordable range (usually 50 – 100 copies/ml). The viral load can be in the hundreds of thousands in untreated HIV.

Answer 116

All patients started on an Antiretroviral therapy (ART) regardless of Viral load of CD4 count BHIVA guidelines recommend a starting regime of 2 x **Nucelotide Reverse Transcriptase Inhibitors** (NRTI) e.g. tenofovir and emtricitabine plus a third agent

Answer 117

The aim of treatment is to achieve a normal CD4 count and undetectable viral load. As a general rule when a patient has normal CD4 and undetectable VL on ART treat their physical health problems (e.g. routine chest infections) as you would an HIV -ve patient. When prescribing be aware and check interactions any medication might have with the HIV therapy

Answer 118

- Protease Inhibitors (PIs) - Integrase Inhibitors (IIs) - Nucleoside Reverse Transcriptase Inhibitors (NRTIs) - Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) - Entry Inhibitors (EIs)

Answer 119

Prophylactic co-trimoxazole (Septrin) is given to patients with CD4 < 200/mm3 to protect against pneumocystis jirovecii pneumonia (PCP). HIV infection increases the risk of developing cardiovascular disease. Patients with HIV have close monitoring of cardiovascular risk factors and blood lipids and appropriate treatment (such as statins) to reduce their risk of developing cardiovascular disease. Yearly cervical smears are required for women. HIV predisposes to developing cervical human papillomavirus (HPV) infection and cervical cancer so female patients need close monitoring to ensure early detection of these complications. Vaccinations should be up to date including annual influenza, pneumococcal (every 5-10 years), hepatitis A and B, tetanus, diphtheria and polio. Patients should avoid live vaccines

Answer 120

Post exposure prophylaxis can be used after exposure to HIV to reduce the risk of transmission. It is not 100% effective and must be commenced within a short period (less than 72 hours). The sooner it is started the better. A risk assessment about the probability of developing HIV should be balanced against the side effects of post exposure prophylaxis. It involves a combination of ART therapy. The current regime is Truvada (emtricitabine / tenofovir) and raltegravir for 28 days. HIV tests should be done initially but also a minimum of 3 months after exposure to confirm a negative status. Individuals should abstain from unprotected activity for a minimum of 3 months until confirmed negative

Answer 121

Malaria is an infectious disease caused by members of the Plasmodium family of protozoan parasites. Protozoa are single celled organisms. The most severe and dangerous member of the family is Plasmodium falciparum. This accounts for about 75% of the cases of malaria in the UK. Malaria is spread through bites from the female Anopheles mosquitoes that carry the disease. It commonly occurs in travellers to areas where malaria is known to be present

Answer 122

Plasmodium falciparum is the most severe and dangerous form Plasmodium vivax Plasmodium ovale Plasmodium malariae

Answer 123

Malaria is spread by female Anopheles mosquitoes, most commonly at night time. Infected blood is sucked up by feeding mosquito. The malaria in the blood reproduces in the gut of the mosquito producing thousands of sporozoites (malaria spores). When that mosquito bites another human or animal the sporozoites are injected by the mosquito. These sporozoites travel to the liver of the newly infected person. They can lie dormant as hypnozoites for several years in P. vivax and P. ovale. They mature in the liver into merozoites which enter the blood and infect red blood cells. In red blood cells the merozoites reproduce over 48 hours, after which the red blood cells rupture releasing loads more merozoites into the blood and causing a haemolytic anaemia. This is why people infected with malaria have high fever spikes every 48 hours.

Answer 124

Suspected malaria in someone who lives or has travelled to an area of malaria. The incubation period is 1-4 weeks after infection with malaria although it can lie dormant for years. Non-specific Symptoms - Fever, sweats and rigors - Malaise - Myalgia - Headache - Vomiting Signs - Pallor due to the anaemia - Hepatosplenomegaly - Jaundice as bilirubin is released during the rupture of red blood cells

Answer 125

A diagnosis can be made using a malaria blood film. This is sent in an EDTA bottle (the red top bottle used for a FBC). Examining the malaria blood film will show the parasites, the concentration and also what type they are. 3 samples are sent over 3 consecutive days to exclude malaria. This is due to the 48 hour cycle of malaria being released into the blood from red blood cells. The sample may be negative on days where the parasite is not released but becomes positive a day or two later when they are released from the RBCs.

Answer 126

Discuss patients with the local infectious diseases unit for advice on management. All patients with falciparum malaria should be admitted for treatment as they can deteriorate quite quickly. Oral options in uncomplicated malaria: Artemether with lumefantrine (Riamet) Proguanil and atovaquone (Malarone) **Quinine sulphate** Doxycycline Intravenous options in severe or complicated malaria: **Artesunate**. This is the most effective treatment but is not licensed. Quinine dihydrochloride

Answer 127

- Cerebral malaria - Seizures - Reduced consciousness - Acute kidney injury - Pulmonary oedema - Disseminated intravascular coagulopathy (DIC) - Severe haemolytic anaemia - Multi-organ failure and death

Answer 128

General advice: - Be aware of locations that are high risk - No method is 100% effective alone - Use mosquito spray (e.g. 50% DEET spray) in mosquito exposed areas - Use mosquito nets and barriers in sleeping areas - Seek medical advice if symptoms develop - Take antimalarial medication as recommended

Answer 129

Proguanil and Atovaquone (Malarone), Mefloquine and Doxycycline

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