CDM revision Sem 2 Flashcards
What is the classic triad for Behcet’s disease?
The classic triad in Behcet’s is oral ulcers, genital ulcers and uveitis. Venous thromboembolism is also seen.
What ia most severe manifestation of chronic Chagas’ disease?(how is transmitted?
Cardiomyopathy is the most frequent and most severe manifestation of chronic Chagas’ disease
Important for meLess important
Trypanosoma cruzi.
What is the most common cause of travellers diarrhea?
E-coli
Where does does pseudomonas cause infection and how is it treated?
Pseudomonas aeruginosa is a gram-negative rod that is an important cause of infections in immunocompromised or severely ill patients. It is a multi-drug resistant pathogen (in part aided by the ability to form biofilms) that frequently colonizes medical devices, and can secrete a wide host of virulence factors and exotoxins.
Pseudomonas commonly infects the airway, urinary tract and wounds or sites of entry for hospital devices/lines. Important diseases include the following:
Pneumonia: particularly ventilator-associated pneumonia, as well as pneumonia in Cystic fibrosis (80% are colonized, and once infection is established it can be very hard to treat)
Urinary tract infections: usually hospital acquired and associated with urinary tract catheterization or surgery.
Surgical wound and skin infections: skin lesions may include ecthyma gangrenosum
Sepsis in hospital/ nursing home inpatients
Infective endocarditis: especially in intravenous drug users or those with prosthetic heart valves
Ear infections: chronic otitis media as well as otitis externa (including malignant otitis externa)
Eye infections: bacterial keratitis and endophthalmitis (risk factors being trauma and wearing contact lenses)
Bones and joints: can cause osteomyelitis or septic arthritis, particularly in spine, pelvis and sternoclavicular joints. Being diabetic or an IVDU are risk factors.
Antibiotics which are effective against Pseudomonas:
Ciprofloxacin or levofloxacin (but not moxifloxacin) - note, this is the only oral anti-pseudomonal Tazocin Ceftazidime Meropenem Gentamicin
What investigations are done for typhoid?
Investigations: Note that the isolation of S.typhi is highest in the first week and becomes more difficult as time passes.
Blood culture - 80% positivity if two sets were taken.
bone marrow culture - most sensitive source.
Stool cultures
Widal test (for antibodies against Salmonella antigens), not very sensitive or specific.
Management:
Empirical antibiotics: Ciprofloxacin unless resistant. Alternatives include ceftriaxone, chloramphenicol or Azithromycin (if uncomplicated).
Supportive therapy: hydration, nutrition, antipyretics etc.
May need surgery for bowel perforation
Hygiene and close attention to hand washing must be emphasized to the patient and all close contacts.
What is the first line treatment of PCP?
Cotrimazole
How is Rheumatic fever diagnosed?
Acute or Chronic Rheumatic Fever - this is a multisystem autoimmune phenomenon affecting the heart, joints, skin, brain and subcutaneous tissue. It is caused by molecular mimicry, when shared epitopes between the host and group A strep lead to the immune system mistaking host tissues as ‘foreign,’- the most important being the Streptococcal M protein, which causes immune cross-reactivity with cardiac myosin. Patients commonly present with joint involvement (usually a migrating polyarthritis) as well as mitral valve regurgitation or stenosis. The modified Jones criteria is used for diagnosis (see below). It is rare in developed countries, but still commonly affects children (between 5-15 years) in developing countries - this is thought to be due to overcrowding, malnourishment and poor use of antibiotics to treat strep throat infections
Modified Jones criteria: 2 major or 1 major + 2 minor
Major criteria: Carditis, arthritis, erythema marginatum, Sydenham’s chorea, or subcutaneous nodules
Minor criteria: Fever, arthralgia, raised ESR/CRP, raised WCC, ECG showing heart block, previous rheumatic heart disease
Causes of pneumonia in homeless people: malnourished, alcohol or drug dependent, immunosuppressed
Homeless people: malnourished, alcohol or drug dependent, immunosuppressed
Mycobacterium tuberculosis
Aspiration pneumonia (infection with normal flora of mouth and anaerobes, also consider in any patient with an unsafe swallow or with depressed consciousness)
Klebsiella pneumoniae (causes ‘red-current jelly’ sputum, and commonly causes lung abscess formation and empyema)
How does Legionella pneumonia present?
Legionnaire’s disease is caused by the intracellular bacterium Legionella pneumophilia. It typically colonizes water tanks and hence questions may hint at air-conditioning systems or foreign holidays. Person-to-person transmission is not seen
Features flu-like symptoms including fever (present in > 95% of patients) dry cough relative bradycardia confusion lymphopaenia hyponatraemia deranged liver function tests pleural effusion: seen in around 30% of patients
Diagnosis
urinary antigen
Management
treat with erythromycin/clarithromycin
How is tapeworm infestation treated?
Praziquantel and Niclosamide
This is a description of Taeniasis or tapeworm. It can be contracted by eating uncooked pork or beef as the eggs are laid in meat. The patient describes seeing grapefruit seeds in his stool, these are proglottids which are tapeworm segments. It can be treated with anti-parasitic therapy.
How is rheumatic fever treated and what are the complications?
Management of rheumatic fever involves multiple goals:
Eradication of group-A beta-haemolytic streptococcal infection
STAT dose of IV Benzylpenicillin, with a ten day course of Phenoxymethylpenicillin to follow
Analgesia for arthritic symptoms
Aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen.
Aspirin should be used with caution in young children due to the small risk of Reye syndrome.
There is no evidence to suggest that NSAIDs help with outcomes related to carditis.
If carditis is complicated by heart failure
Glucocorticoids (e.g. Prednisolone) can provide benefit (NSAIDs should be stopped concurrently).
Diuretic treatment may also be necessary, and valve surgery if severe.
Sydenham’s chorea is self-limiting and does not require treatment, however Haloperidol or Diazepam may be used for distressing symptoms or risk of harm.
Erythema marginatum is associated with rheumatic fever is temporary and doesn’t require treatment, although antihistamines can help with pruritus.
Mechanism of valve complications
Rheumatic heart disease is a major cause of valvulopathy in children and young adults in the developing world. The most recent study in 2015 suggests that year there were over 30 million cases worldwide. Streptococcal antigens secondary to bacterial infection cross-reacts with the valve tissue, causing damage. Progressive damage commonly occurs in the years following acute rheumatic fever.
Mitral disease occurs in 70% of cases and is the most common affected valve; aortic valves are involved in 40% (most commonly regurgitation), tricuspid valves in 10% and pulmonary valves in 2%.
most commonly diagnosed sexually transmitted infection in the UK?
Chlamydia
How is toxoplasmosis treated?
Immunocompromised patients with toxoplasmosis are treated with pyrimethamine plus sulphadiazine
Who develops CMV retinitis?
CMV retinitis
common in HIV patients with a low CD4 count (< 50)
presents with visual impairment e.g. ‘blurred vision’. Fundoscopy shows retinal haemorrhages and necrosis, often called ‘pizza’ retina
IV ganciclovir is the treatment of choice
Cytomegalovirus (CMV) infection is important to consider in renal transplant patients.
First line treatment for gonorrhoea and chlamydia?
Gonorrhoea Intramuscular ceftriaxone
Chlamydia Doxycycline or azithromycin
What are the features and complications of mycoplasma infection?
Mycoplasma pneumoniae is a cause of atypical pneumonia which often affects younger patients. It is associated with a number of characteristic complications such as erythema multiforme and cold autoimmune haemolytic anaemia. Epidemics of Mycoplasma pneumoniae classically occur every 4 years. It is important to recognise atypical pneumonia as it may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall.
Features
the disease typically has a prolonged and gradual onset
flu-like symptoms classically precede a dry cough
bilateral consolidation on x-ray
complications may occur as below
Complications
cold agglutins (IgM): may cause an haemolytic anaemia, thrombocytopenia
erythema multiforme, erythema nodosum
meningoencephalitis, Guillain-Barre syndrome and other immune-mediated neurological diseases
bullous myringitis: painful vesicles on the tympanic membrane
pericarditis/myocarditis
gastrointestinal: hepatitis, pancreatitis
renal: acute glomerulonephritis
Investigations
diagnosis is generally by Mycoplasma serology
positive cold agglutination test
Management
doxycycline or a macrolide (e.g. erythromycin/clarithromycin)
How is hospital acquired pneumonia treated?
Within 5 days of admission: co-amoxiclav or cefuroxime
More than 5 days after admission: piperacillin with tazobactam OR a broad-spectrum cephalosporin (e.g. ceftazidime) OR a quinolone (e.g. ciprofloxacin)
Name 4 radiological (x-ray) signs of rheumatoid arthritis of the hands?
Narrowing of joint space Marginal erosions Periarticular osteopenia / osteoporosis Irregular joint surface Deformity / subluxation / dislocation / malalignment Soft tissue swelling
Name 4 organs and the associated pathology (not including any in the musculoskeletal system) which manifest as part of the systemic disease process of rheumatoid arthritis?
Skin (Rheumatoid nodules)
Eyes (episcleritis / kerato-conjunctivitis sicca)
Heart (pericarditis)
Lungs (rheumatoid nodules in lungs)
Spleen (Splenomegaly, Felty’s syndrome)
Blood (normochromic normocytic anaemia ; iron-deficiency anaemia; anaemia of chronic disease)
Renal (renal impairment / amyloidosis)
Gastrointestinal (stomach ulcers, GI bleeding, oesophagitis, amyloidosis)
What is Pityriasis rosea and how does it present?
Pityriasis rosea is a common rash which often occurs after an upper respiratory tract infection and is thought to have a viral cause (HHV 6/7).
It is characterized by a preceding herald patch - a single, large, discoid (coin-shaped), erythematous patch. This patch classically has a ‘collarette’ of scale just inside the edge of the lesion. A few days later a widespread rash appears across the trunk consisting of multiple small, erythematous, scaly patches (similar but smaller than the herald patch). These lesions are classically distributed across the trunk in a ‘christmas tree’ pattern.
Pityriasis rosea is self-limiting and benign. No treatment is required and it will usually resolve over a few weeks.
May need
Topical steroids and emollients. UV therapy is sometimes used.
Which cells are squamous cell carcinomas derived from and what are the commonest sites?What is the biggest risk factor
Keratinocytes
Backs of hands, face, edge of scars
Sun damage or sun exposure
What Investigations are done for Sjorgens
Blood tests:
Markers of inflammation are usually raised.
Autoantibodies:
Most patients are ANA positive but this is not specific for Sjogren’s syndrome.
Anti-Ro and Anti-La Autoantibodies are both specific for Sjogren’s syndrome.
Special tests for Sjogren’s syndrome
Schirmer’s test - this demonstrates reduced tear production using a strip of filter paper on the lower eyelid: wetting of <5mm is positive.
Rose bengal staining - this demonstrates keratitis due to conjunctivitis sicca when using a slit-lamp.
Salivary flow rate monitoring - this demonstrates xerostomia using a radiolabelled dye (uptake and excretion by the salivary gland is slowed).
Salivary gland biopsy - histology may confirm the diagnosis.
How can polymyalgia be treated and what Investigations need to be done before hand?
The treatment for polymyalgia rheumatica is steroids.
Unlike giant cell arteritis, steroids do not need to be started straight away giving time for an initial work-up to minimise risks of steroid use.
After initial investigations, before commencing treatment for Polymyalgia rheumatica the following work up should be done:
Prevention and treatment of steroid induced osteoporosis: DEXA scan those with high fracture risk. DEXA scanning is recommended in those without high fracture risk too.
Screening for increased risk of adverse reaction to steroids before starting: diabetes mellitus, hypertension, history of peptic ulcer, osteoporosis, mental health history.
What are the extra articular manifestation of osteoarthritis?
Extra-articular features:
Rheumatoid arthritis (RA) is a multisystem inflammatory disease and can affect most organs.
General:
Patients often feel generally unwell with RA, including low grade fevers, weight loss, and fatigue.
Haematological:
Anaemia of chronic disease - this is common in RA (note that most DMARDs can also cause cytopenias as a side effect).
Splenomegaly including Felty’s syndrome (triad of RA, splenomegaly and neutropenia).
Amyloidosis – most organs can be affected, classically the kidneys causing nephrotic syndrome.
Generalised lymphadenopathy.
Dermatological:
Rheumatoid nodules (firm, dark skin nodules, usually around sites of inflammation).
Small vessel vasculitis causing nailbed infarcts and arterial leg ulcers.
Raynaud’s syndrome.
Ophthalmic:
Keratoconjunctivitis sicca (dry eyes) – this can occur on its own, or as part of secondary Sjogren’s syndrome with oral, genital and gastric ulcers.
Episcleritis and scleritis.
Respiratory
Pleural effusions containing rheumatoid factor.
Rheumatoid nodules may be seen on chest x-ray, and are asymptomatic.
Pneumonitis leading to pulmonary fibrosis (note that this can also be a side effect of methotrexate).
Orthopaedic:
Osteoporosis.
Cardiac:
Pericardial effusions containing rheumatoid factor.
Strong risk factor for cardiovascular disease.
Neurological:
Peripheral neuropathy.
What are the risk factors for development of basal cell carcinoma?
Immunosuppression
UV exposure
Family history of skin ca
What are the risk factors for pseudo gout?
A diagnosis of pseudogout can be tricky to make. Pseudogout typically affects elderly women, and the joints that are normally affected are the wrists and knees.
The associations are hyperparathyroidism, hypothyroidism, hypophosphataemia, haemochromatosis and Wilson’s disease.
On polarised light microscopy, psedogout presents with positively birefringent rhomboid crystals.
What NSAIDS are safer to use if there is a risk of GI ulceration?
COX-2 inhibitors, also known as coxibs, such as celocoxib are a newer alternative to traditional NSAIDs like ibuprofen or naproxen. Coxibs selectively inhibit COX-2 which confers a lower risk of GI ulceration and so may be preferred in patients at high risk of GI ulceration.
However, shortly after they were first released, the coxib rofecoxib was discontinued because it was found to increased the risk of cardiovascular events to a significantly higher extent than regular NSAIDs. This lead to a lack of uptake in coxib use, but more recent research has found that other coxibs, particularly moderate dose celocoxib, confers an equivalent cardiovascular risk to normal NSAIDs and are therefore safe to use in place of regular NSAIDs where necessary.
What complication to the eyes can occur due to hydroxychloroquine use?
bullseye maculopathy-reduced visual acuity and colour vision
annular lesions bilaterally around macular on fundoscope
if suspected stop drug
How is Turner’s syndrome inherited?
This is a typical presentation of Turner’s syndrome. She has a webbed neck and
short stature which represent characteristic physical appearance. Infertility
is usually how these patients present. Genotype is XO and majority of foetuses
with this genetic make-up will spontaneously abort. As such, a live Turner’s
syndrome lady is most likely to be caused by mosaicism. Some cells are XO,
some are normal (XX).
The physiological process of X inactivation in an XX
female leads to creation of which cellular structure?
The normal state of genetic material in cells compromises two active sets of
autosomes (the non-sex chromosomes) and one active X chromosome in the female,
or in males who have multiple X chromosomes (Klinefelter’s syndrome). The X
chromosome that is “inactivated” becomes condensed, meaning it cannot be
replicated (hence inactivated) and this creates the Barr Body - the condensed
chromosome pushed against the nuclear membrane. They are rendered inactive in
a process called lyonisation.
What diagnostic tests can be used to identify if a foetus has Down syndrome?
As she has booked in at 9 weeks, you can carry
out chorionic villous sampling, which is undertaken at 10-14 weeks. It
involves taking a small sample of cells called chorionic villi from theplacenta where it attaches to the wall of the uterus. Genetic analysis can
then be carried out on these cells to determine the karyotype.
If she had presented later, amniocentesis can be undertaken at 13-15 weeks;
here, a sample of amniotic fluid, not placenta, is taken and tested.
Ultrasound to determine the ‘nuchal thickness’ and blood tests such as beta
hCG and PAPP-A are routinely used to screen for Down’s syndrome, but do not
involve obtaining a placental sample and are also screening tests, rather than
being diagnostic.
How is Osteogenesis Imperfects inherited?
Osteogenesis imperfecta is an autosomal dominant condition of collagen,
resulting in bone material being more supple and so fractures occur more
commonly. The type 1 procollagen compromises two chains encoded by COL1A1 gene
and one chain encoded for by COL1A2. A mutation in either of these genes
results in disruption of the whole fibril.
It’s mechanism of dominant inheritance is said to be the dominant negativeeffect. This is where the product of a defective gene (e.g. in this case,
either COL1A1 or COL1A2) interferes with the action of the normal allele (e.g.
here, whichever of COL1A1 or COL1A2 is not mutated). These usually need to
form units called “multimers” - proteins that work together to form a complex
structure.
What TB drug is most likely to cause hepatotoxicity?
Isoniazid more likely to cause hepatotoxicity than rifampicin
When should BCG vaccine be offered
Give BCG vaccination
According to NICE guidelines, BCG vaccination should be given to tuberculin skin test negative (mantoux negative) contacts of patients with confirmed pulmonary and laryngeal TB, who have not been previously vaccinated and are under the age of 35 or are over the age of 35 and work in healthcare.
This patient had a negative test with only 1mm induration, a positive result would have been 5mm or more.
What are the adverse effects of Ciprofloxacin
Ciprofloxacin
This is associated with increased risk of Achilles tendinopathy and tendon rupture, although this is rare. It may also cause lowering of seizure threshold, prolongation of QT interval and Clostridium difficile colitis.
What is the most common cause of food poisoning in the UK?
Campylobacter jejuni
This is the most common cause of food poisoning in the UK, and is usually associated with eating contaminated or undercooked chicken. Summer BBQs are classically associated small outbreaks or groups of cases. Diarrhoea is often dysenteric (containing blood and mucus) due to bacterial invasion of the intestinal mucosa
What is the first line empirical therapy for Neutropenic sepsis?
DRABCDE approach
If low risk can give oral antibiotics (quinolone + co-amoxiclav)
Features suggesting low risk: Hemodynamically stable Doesn't have acute leukemia No organ failure No soft tissue infection No indwelling lines
For most patients, they need empirical IV treatment with piperacillin and tazobactam (tazocin), with added coverage for MRSA or gram-negatives if thought at risk. A macrolide should also be added if diagnosed with pneumonia (to cover atypical organisms)
May need 2-hourly assessments
Daily measures of fever and baseline bloods until the patient is apyrexial and neutrophil count above 0.5x10^9
When the neutrophil count is normal, has been afebrile for 48 hours and blood tests have normalized, antibiotics can be stopped.
Prophylaxis with a fluoroquinolone can be offered
What Investigations are done for TB?
Investigations
Chest X-ray
Sputum samples for culture and sensitivity testing (at least three needed - may need to consider lavage or sputum induction if cannot produce)
Samples from non-pulmonary sites: may need biopsy and needle aspiration
Samples are stained with Ziehl-Neelsen or Auramine staining for direct microscopy
For culture, Lowenstein-Jensen (LJ) media is needed.
PCR - GeneXpert, rapid results with additional drug sensitivity tested as well.
Interferon-Gamma Release Assays (IGRAs) - cannot tell difference between latent or active TB, and not useful in very young or immunosuppressed patients. Results are obtained rapidly, however, and are not affected by prior BCG.
Mantoux test - usually offered to contacts of infected patients. Positive in those who have had the BCG vaccine.
Management
What is Psoa’s sign”?
Severe pain whenever the left hip is hyperextended.
How can coagulase negative staph IE be treated?
Vancomycin
32%
Coagulase-negative staphylococci are the most common cause of endocarditis associated with hospital in-dwelling lines. Glycopeptides are first-line treatment
What are examples of live vaccines
Live attenuated vaccines BCG MMR oral polio yellow fever oral typhoid
How can hospital acquired pneumonia be treated?
Within 5 days of admission: co-amoxiclav or cefuroxime
More than 5 days after admission: piperacillin with tazobactam OR a broad-spectrum cephalosporin (e.g. ceftazidime) OR a quinolone (e.g. ciprofloxacin)
What is th risk of infection following splenectomy and how can this be managed?
Organisms causing post splenectomy sepsis:
Streptococcus pneumoniae
Haemophilus influenzae
Meningococci
Important for meLess important
Encapsulated organisms carry the greatest pathogenic risk following splenectomy. The effects of sepsis following splenectomy are variable. This may be the result of small isolated fragments of splenic tissue that retain some function following splenectomy. These may implant spontaneously following splenic rupture (in trauma) or be surgically implanted at the time of splenectomy.
Management
Key recommendations
All those with hyposplenism or may become so (such as prior to an elective splenectomy) should receive pneumococcal, Haemophilus type b and meningococcal type C vaccines. These should be administered 2 weeks prior to splenectomy or two weeks following splenectomy. The vaccine schedule for meningococcal disease essentially consists of a dose of Men C and Hib at 2 weeks and then a dose of the MenACWY vaccine one month later. Those aged under 2 may require a booster at 2 years. A dose of pneumococcal polyvalent polysaccharide vaccine (PPV) is given at two weeks. A conjugated vaccine (PCV) is offered to young children. The PCV is more immunogenic but covers fewer serotypes. Boosting PPV is either guided by serological measurements (where available) or by routine boosting doses at 5 yearly intervals.
Annual influenza vaccination is recommended in all cases
Antibiotic prophylaxis is offered to all. The risk of post-splenectomy sepsis is greatest immediately following splenectomy and in those aged less than 16 years or greater than 50 years. Individuals with a poor response to pneumococcal vaccination are another high-risk group. High-risk individuals should be counselled to take penicillin or macrolide prophylaxis. Those at low risk may choose to discontinue therapy. All patients should be advised about taking antibiotics early in the case of intercurrent infections.
Asplenic individuals travelling to malaria endemic areas are at high risk and should have both pharmacological and mechanical protection.
Dosing
Penicillin V 500mg BD or amoxicillin 250mg BD
When should tetanus vaccine be given?
Patients with an uncertain tetanus vaccination history should be given a booster vaccine + immunoglobulin, unless the wound is very minor and < 6 hours old
Important for meLess important
In this case, the most appropriate course of action is to give a tetanus booster and tetanus immunoglobulin. This man has an unknown vaccination, a tetanus prone wound (occurred whilst gardening) and it is more than 6 hours old.
Metronidazole antibiotic is the treatment for tetanus rather than being used as a prophylactic agent.
A tetanus booster alone is sufficient if a patient has a tetanus prone wound with a full vaccination history but the last dose being more than 10 years ago.
Tetanus immunoglobulin can be used to treat proven cases of tetanus. In this case, as the vaccination history is not known a tetanus booster and immunoglobulin should be given.
Simple wound cleaning can be used if a patient has had a full course of tetanus vaccines, with the last dose less than 10 years ago, irrespective of the severity of the wound. The vaccination history is not known in this case so wound cleaning only would not be appropriate
What is the first line treatment for cellulitis
The BNF recommends flucloxacillin as first-line treatment for mild/moderate cellulitis. Clarithromycin, erythromycin (in pregnancy) or doxycyline is recommended in patients allergic to penicillin.
NICE recommend that patients severe cellulitis should be offered co-amoxiclav, cefuroxime, clindamycin or ceftriaxone.
What adverse reaction is seen with the use of metronidazole?
The combination of metronidazole and ethanol can cause a disulfiram-like reaction. Clinical features of this include head and neck flushing, nausea and vomiting, sweatiness, headache and palpitations.
Cefoperazone, a cephalosporin, is also associated with a disulfiram-like reaction to alcohol.
How can Parvovirus B19 trigger an aplastic crisis ?
Parvovirus B19 is the most likely infective cause of an aplastic anaemia crisis in patients with sickle cell disease
Important for meLess important
Erythema infectiosum is caused by parvovirus B19, a virus that reduces erythropoiesis for about a week. Those who already have a chronic haemolytic anaemia (e.g. sickle cell disease) are at high risk of aplastic anaemia.
What is the first line treatment for syphilis and what reaction is seen?
Management
intramuscular benzathine penicillin is the first-line management
alternatives: doxycycline
the Jarisch-Herxheimer reaction is sometimes seen following treatment
fever, rash, tachycardia after the first dose of antibiotic
in contrast to anaphylaxis, there is no wheeze or hypotension
it is thought to be due to the release of endotoxins following bacterial death and typically occurs within a few hours of treatment
No treatment is needed other than antipyretics if required
What organisms can cause necrotising fasciitis
Necrotising fasciitis is a medical emergency that is difficult to recognise in the early stages.
It can be classified according to the causative organism:
type 1 is caused by mixed anaerobes and aerobes (often occurs post-surgery in diabetics). This is the most common type
type 2 is caused by Streptococcus pyogenes
Risk factors
skin factors: recent trauma, burns or soft tissue infections
diabetes mellitus
the most common preexisting medical condition
particularly if the patient is treated with SGLT-2 inhibitors
intravenous drug use
immunosuppression
The most commonly affected site is the perineum (Fournier’s gangrene).
Features
acute onset
pain, swelling, erythema at the affected site
often presents as rapidly worsening cellulitis with pain out of keeping with physical features
extremely tender over infected tissue with hypoaesthesia to light touch
skin necrosis and crepitus/gas gangrene are late signs
fever and tachycardia may be absent or occur late in the presentation
Management
urgent surgical referral debridement
intravenous antibiotics
Prognosis
average mortality of 20%
What post exposure prophylaxis is given in Hep A,B,C and HIV
Hepatitis A
Human Normal Immunoglobulin (HNIG) or hepatitis A vaccine may be used depending on the clinical situation
Hepatitis B
HBsAg positive source: if the person exposed is a known responder to HBV vaccine then a booster dose should be given. If they are in the process of being vaccinated or are a non-responder they need to have hepatitis B immune globulin (HBIG) and the vaccine
unknown source: for known responders the green book advises considering a booster dose of HBV vaccine. For known non-responders HBIG + vaccine should be given whilst those in the process of being vaccinated should have an accelerated course of HBV vaccine
Hepatitis C
monthly PCR - if seroconversion then interferon +/- ribavirin
HIV
the risk of HIV transmission depends heavily on the incident (e.g. needle stick, type of sexual intercourse, human bite etc) and the current viral load of the patient
please see the BHIVA link for charts which outline the risk depending on the incident. Generally, low-risk incidents such as human bites don’t require post-exposure prophylaxis
a combination of oral antiretrovirals (e.g. Tenofovir, emtricitabine, lopinavir and ritonavir) as soon as possible (i.e. Within 1-2 hours, but may be started up to 72 hours following exposure) for 4 weeks
serological testing at 12 weeks following completion of post-exposure prophylaxis
reduces risk of transmission by 80%
Varicella zoster
VZIG for IgG negative pregnant women/immunosuppressed
How does CSF of TB meningitis look?
The table below summarises the characteristic cerebrospinal fluid (CSF) findings in meningitis:
Bacterial Viral Tuberculous Fungal
Appearance Cloudy Clear/cloudy Slight cloudy, fibrin web Cloudy
Glucose Low (< 1/2 plasma) 60-80% of plasma glucose* Low (< 1/2 plasma) Low
Protein High (> 1 g/l) Normal/raised High (> 1 g/l) High
White cells 10 - 5,000 polymorphs/mm³ 15 - 1,000 lymphocytes/mm³ 30 - 300 lymphocytes/mm³ 20 - 200 lymphocytes/mm³
The Ziehl-Neelsen stain is only 20% sensitive in the detection of tuberculous meningitis and therefore PCR is sometimes used (sensitivity = 75%)
*mumps is unusual in being associated with a low glucose level in a proportion of cases. A low glucose may also be seen in herpes encephalitis
What are the features of congenital syphilis?
Features of congenital syphilis
blunted upper incisor teeth (Hutchinson’s teeth), ‘mulberry’ molars
rhagades (linear scars at the angle of the mouth)
keratitis
saber shins
saddle nose
deafness
How is chlamydia diagnosed and treated?
Chlamydia is the most commonly diagnosed sexually transmitted infection. It can be asymptomatic and if left untreated can cause complications such as pelvic inflammatory disease and infertility. It is diagnosed using nucleic acid amplification tests (NAATs). Women can do a self swab and men can do a first pass urine sample. Gonorrhoea is also diagnosed using NAATs.
Treatment of Chlamydia is with azithromycin or doxycycline.
Chlamydia is the most prevalent sexually transmitted infection in the UK and is caused by Chlamydia trachomatis, an obligate intracellular pathogen. Approximately 1 in 10 young women in the UK have Chlamydia. The incubation period is around 7-21 days, although it should be remembered a large percentage of cases are asymptomatic
Features
asymptomatic in around 70% of women and 50% of men
women: cervicitis (discharge, bleeding), dysuria
men: urethral discharge, dysuria
Potential complications epididymitis pelvic inflammatory disease endometritis increased incidence of ectopic pregnancies infertility reactive arthritis perihepatitis (Fitz-Hugh-Curtis syndrome)
Investigation
traditional cell culture is no longer widely used
nuclear acid amplification tests (NAATs) are now the investigation of choice
urine (first void urine sample), vulvovaginal swab or cervical swab may be tested using the NAAT technique
for women: the vulvovaginal swab is first-line
for men: the urine test is first-line
Chlamydiatesting should be carried out two weeks after a possible exposure
Screening
in England the National Chlamydia Screening Programme is open to all men and women aged 15-24 years
the 2009 SIGN guidelines support this approach, suggesting screening all sexually active patients aged 15-24 years
relies heavily on opportunistic testing
Management
doxycycline (7 day course) if first-line
this is now preferred to azithromycin due to concerns about Mycoplasma genitalium. This infection is often coexistant in patients with Chlamydia and there is evidence of rising levels of macrolide resistance, hence why doxycycline is preferred
if doxycycline is contraindicated / not tolerated then either azithromycin (1g od for one day, then 500mg od for two days) should be used
if pregnant then azithromycin, erythromycin or amoxicillin may be used. The SIGN guidelines suggest azithromycin 1g stat is the drug of choice ‘following discussion of the balance of benefits and risks with the patient’
patients diagnosed with Chlamydia should be offered a choice of provider for initial partner notification - either trained practice nurses with support from GUM, or referral to GUM
for men with urethral symptoms: all contacts since, and in the four weeks prior to, the onset of symptoms
for women and asymptomatic men all partners from the last six months or the most recent sexual partner should be contacted
contacts of confirmed Chlamydia cases should be offered treatment prior to the results of their investigations being known (treat then test)
How can different causes of meningitis be differentiated by microbiology
The clinical presentation raises a suspicion of meningitis. Streptococcus pneumoniae, Neisseria meningitidis, Mycobacterium tuberculosis and Cryptococcus neoformans are causative organisms of meningitis. The India ink stain on cerebrospinal fluid (CSF) analysis points towards Cryptococcus neoformans as the causative organism. Streptococcus pneumoniae would have a gram-positive stain while Neisseria meningitidis would have a gram-negative stain. Mycobacterium tuberculosis would have a Ziehl–Neelsen (acid-fast) stain. In toxoplasmosis, the head CT usually shows single or multiple ring enhancing lesions, and mass effect may be seen
What is red mans syndrome
Red man syndrome is associated with rapid intravenous infusion vancomycin. It is a common adverse reaction of intravenous vancomycin use and is a distinct entity from anaphylaxis due to vancomycin use. Typical symptoms include redness, pruritus and a burning sensation, predominantly in the upper body (face, neck and upper chest). Severe cases can be associated with hypotension and chest pain.
The pathophysiology of red man syndrome is attributed to vancomycin-related activation of mast cells with release of histamine.
The management of red man syndrome involves cessation of the infusion, and when symptoms have resolved, recommencement at a slower rate. In patients who are more symptomatic antihistamines can be administered, and may require intravenous fluids if the syndrome is associated with hypotension.
How can MRSA be treated and cleared?
Methicillin-resistant Staphylococcus aureus (MRSA) was one of the first organisms which highlighted the dangers of hospital-acquired infections.
Who should be screened for MRSA?
all patients awaiting elective admissions (exceptions include day patients having terminations of pregnancy and ophthalmic surgery. Patients admitted to mental health trusts are also excluded)
from 2011 all emergency admissions will be screened
How should a patient be screened for MRSA?
nasal swab and skin lesions or wounds
the swab should be wiped around the inside rim of a patient’s nose for 5 seconds
the microbiology form must be labelled ‘MRSA screen’
Suppression of MRSA from a carrier once identified
nose: mupirocin 2% in white soft paraffin, tds for 5 days
skin: chlorhexidine gluconate, od for 5 days. Apply all over but particularly to the axilla, groin and perineum
The following antibiotics are commonly used in the treatment of MRSA infections:
vancomycin
teicoplanin
linezolid
Some strains may be sensitive to the antibiotics listed below but they should not generally be used alone because resistance may develop: rifampicin macrolides tetracyclines aminoglycosides clindamycin
Relatively new antibiotics such as linezolid, quinupristin/dalfopristin combinations and tigecycline have activity against MRSA but should be reserved for resistant cases
Antibiotic guidelines
Condition Recommended treatment
Exacerbations of chronic bronchitis Amoxicillin or tetracycline or clarithromycin
Uncomplicated community-acquired pneumonia Amoxicillin (Doxycycline or clarithromycin in penicillin allergic, add flucloxacillin if staphylococci suspected e.g. In influenza)
Pneumonia possibly caused by atypical pathogens Clarithromycin
Hospital-acquired pneumonia Within 5 days of admission: co-amoxiclav or cefuroxime
More than 5 days after admission: piperacillin with tazobactam OR a broad-spectrum cephalosporin (e.g. ceftazidime) OR a quinolone (e.g. ciprofloxacin)
Urinary tract
Condition Recommended treatment
Lower urinary tract infection Trimethoprim or nitrofurantoin. Alternative: amoxicillin or cephalosporin
Acute pyelonephritis Broad-spectrum cephalosporin or quinolone
Acute prostatitis Quinolone or trimethoprim
Skin
Condition Recommended treatment
Impetigo Topical hydrogen peroxide, oral flucloxacillin or erythromycin if widespread
Cellulitis Flucloxacillin (clarithromycin, erythromycin or doxycycline if penicillin-allergic)
Cellulitis (near the eyes or nose) Co-amoxiclav (clarithromycin, + metronidazole if penicillin-allergic)
Erysipelas Flucloxacillin* (clarithromycin, erythromycin or doxycycline if penicillin-allergic)
Animal or human bite Co-amoxiclav (doxycycline + metronidazole if penicillin-allergic)
Mastitis during breast-feeding Flucloxacillin
Ear, nose & throat
Condition Recommended treatment
Throat infections Phenoxymethylpenicillin (erythromycin alone if penicillin-allergic)
Sinusitis Phenoxymethylpenicillin
Otitis media Amoxicillin (erythromycin if penicillin-allergic)
Otitis externa** Flucloxacillin (erythromycin if penicillin-allergic)
Periapical or periodontal abscess Amoxicillin
Gingivitis: acute necrotising ulcerative Metronidazole
Genital system
Condition Recommended treatment
Gonorrhoea Intramuscular ceftriaxone
Chlamydia Doxycycline or azithromycin
Pelvic inflammatory disease Oral ofloxacin + oral metronidazole or intramuscular ceftriaxone + oral doxycycline + oral metronidazole
Syphilis Benzathine benzylpenicillin or doxycycline or erythromycin
Bacterial vaginosis Oral or topical metronidazole or topical clindamycin
Gastrointestinal
Condition Recommended treatment
Clostridium difficile First episode: metronidazole
Second or subsequent episode of infection: vancomycin
Campylobacter enteritis Clarithromycin
Salmonella (non-typhoid) Ciprofloxacin
Shigellosis Ciprofloxacin
How is HSV 1 and 2 diagnosed and managed?
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
painful genital ulceration
may be associated with dysuria and pruritus
the primary infection is often more severe than recurrent episodes
systemic features such as headache, fever and malaise are more common in primary episodes
tender inguinal lymphadenopathy
urinary retention may occur
Investigations
nucleic acid amplification tests (NAAT) is the investigation of choice in genital herpes and are now considered superior to viral culture
HSV serology may be useful in certain situations such as recurrent genital ulceration of unknown cause
Management
general measures include:
saline bathing
analgesia
topical anaesthetic agents e.g. lidocaine
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
Oral aciclovir 400 mg TDS (three times daily) until delivery is recommended in the RCOG guidelines for women who present with a primary herpes infection in their third trimester of pregnancy, especially if the woman is expected to deliver within 6 weeks.
How is UTI treated in men and pregnant women
Non-pregnant women
local antibiotic guidelines should be followed if available
CKS/2012 SIGN guidelines recommend 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
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
asymptomatic bacteriuria in pregnant women:
a urine culture should be performed routinely at the first antenatal visit
Clinical Knowledge Summaries recommend an immediate antibiotic prescription of either nitrofurantoin (should be avoided near term), amoxicillin or cefalexin. This should be a 7-day course
the rationale of treating asymptomatic bacteriuria is the significant risk of progression to acute pyelonephritis
a further urine culture should be sent following completion of treatment as a test of cure
Men
an immediate antibiotic prescription should be offered for 7 days
as with non-pregnant women, trimethoprim or nitrofurantoin should be offered first-line unless prostatitis is suspected
NICE Clinical Knowledge Summaries state: ‘Referral to urology is not routinely required for men who have had one uncomplicated lower urinary tract infection (UTI).’
Catherised patients
do not treat asymptomatic bacteria in catheterised patients
if the patient is symptomatic they should be treated with an antibiotic
a 7-day, rather than a 3-day course should be given
Acute pyelonephritis
For patients with sign of acute pyelonephritis hospital admission should be considered
local antibiotic guidelines should be followed if available
the BNF currently recommends a broad-spectrum cephalosporin or a quinolone (for non-pregnant women) for 10-14 days
What organisms are patients with cystic fibrosis most at risk of getting?
Patients with cystic fibrosis develop bronchiectasis early on during their life resulting in repeated hospital admissions with lower respiratory tract infections. The pathological process behind bronchiectasis results in sputum pooling within the larger airways with poor removal. Subsequently colonisation occurs with bacteria and occasionally fungi. The most common bacteria is the gram negative rod Pseudomonas aeruginosa and should always be taken into account if providing empirical treatment. If the patient is systemically well then antibiotic sensitivities should be sought from a culture sample before starting treatment. However, an anti-pseudomonal agent such as piperacillin with tazobactam or ciprofloxacin should be used as part of empirical treatment for sepsis in cystic fibrosis patients.
What is Fitz Hugh Curtis syndrome and what conditions can cause this?
Fitz-Hugh-Curtis syndrome is a complication of pelvic inflammatory disease in which the liver capsule becomes inflamed causing right upper quadrant pain. This leads to scar tissue formation and peri-hepatic adhesions. It usually occurs in women who have either chlamydia or gonorrhoea.
Treatment is through eradication of the responsible organism although laparoscopy is required in some patients to perform lysis of adhesions that have formed.
How does leptospirosis present?How is it investigated and managed?
Leptospirosis is caused by the spirochaete Leptospira interrogans (serogroup L. icterohaemorrhagiae), classically being spread by contact with infected rat urine.
Epidemiology
leptospirosis is commonly seen in questions referring to sewage workers, farmers, vets or people who work in an abattoir
however, on an international level, leptospirosis is far more common in the tropics so should be considered in the returning traveller
Weil’s disease should always be considered in high-risk patients with hepatorenal failure
Features
the early phase is due to bacteraemia and lasts around a week
may be mild or subclinical
fever
flu-like symptoms
subconjunctival suffusion (redness)/haemorrhage
second immune phase may lead to more severe disease (Weil’s disease)
acute kidney injury (seen in 50% of patients)
hepatitis: jaundice, hepatomegaly
aseptic meningitis
Investigation
serology: antibodies to Leptospira develop after about 7 days
PCR
culture
growth may take several weeks so limits usefulness in diagnosis
blood and CSF samples are generally positive for the first 10 days
urine cultures become positive during the second week of illness
Management
high-dose benzylpenicillin or doxycycline
What are the causes of traveller’s diarrhoea and acute food poisoning
Gastroenteritis may either occur whilst at home or whilst travelling abroad (travellers’ diarrhoea)
Travellers’ diarrhoea may be defined as at least 3 loose to watery stools in 24 hours with or without one of more of abdominal cramps, fever, nausea, vomiting or blood in the stool. The most common cause is Escherichia coli.
Another pattern of illness is ‘acute food poisoning’. This describes the sudden onset of nausea, vomiting and diarrhoea after the ingestion of a toxin. Acute food poisoning is typically caused by Staphylococcus aureus, Bacillus cereus or Clostridium perfringens
How does botulism present?
Clostridium botulinum
gram positive anaerobic bacillus
7 serotypes A-G
produces botulinum toxin, a neurotoxin which irreversibly blocks the release of acetylcholine
may result from eating contaminated food (e.g. tinned) or intravenous drug use
neurotoxin often affects bulbar muscles and autonomic nervous system
Features patient usually fully conscious with no sensory disturbance flaccid paralysis diplopia ataxia bulbar palsy
Treatment
botulism antitoxin and supportive care
antitoxin is only effective if given early - once toxin has bound its actions cannot be reversed
How does Mycoplasma pneumonia present and how is it investigated and managed?
Mycoplasma pneumoniae is a cause of atypical pneumonia which often affects younger patients. It is associated with a number of characteristic complications such as erythema multiforme and cold autoimmune haemolytic anaemia. Epidemics of Mycoplasma pneumoniae classically occur every 4 years. It is important to recognise atypical pneumonia as it may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall.
Features
the disease typically has a prolonged and gradual onset
flu-like symptoms classically precede a dry cough
bilateral consolidation on x-ray
complications may occur as below
Complications
cold agglutins (IgM): may cause an haemolytic anaemia, thrombocytopenia
erythema multiforme, erythema nodosum
meningoencephalitis, Guillain-Barre syndrome and other immune-mediated neurological diseases
bullous myringitis: painful vesicles on the tympanic membrane
pericarditis/myocarditis
gastrointestinal: hepatitis, pancreatitis
renal: acute glomerulonephritis
Investigations
diagnosis is generally by Mycoplasma serology
positive cold agglutination test
Management
doxycycline or a macrolide (e.g. erythromycin/clarithromycin)
HIV drugs revision
Antiretroviral therapy (ART) involves a combination of at least three drugs, typically two nucleoside reverse transcriptase inhibitors (NRTI) and either a protease inhibitor (PI) or a non-nucleoside reverse transcriptase inhibitor (NNRTI). This combination both decreases viral replication but also reduces the risk of viral resistance emerging
Following the 2015 BHIVA guidelines it is now recommended that patients start ART as soon as they have been diagnosed with HIV, rather than waiting until a particular CD4 count, as was previously advocated.
Entry inhibitors
maraviroc (binds to CCR5, preventing an interaction with gp41), enfuvirtide (binds to gp41, also known as a ‘fusion inhibitor’)
prevent HIV-1 from entering and infecting immune cells
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
‘Navir tease a pro’: HIV drugs that end with -navir are protease inhibitors e.g. ritonavir. Note that due to tolerability issues, ritonavir is now more commonly used to boost the levels of other HIV drugs
‘It’s grave/great you integrate’: HIV drugs that end with -gravir are integrase inhibitors e.g. raltegravir
What to do if patient test negative for HIV on first test?should test be repeated and if so after hoe long?
HIV seroconversion occurs from 3-12 weeks
Important for meLess important
Seroconversion, the period where an antibody response is created and is detectable, can occur between 3 to 12 weeks. Most people create antibodies between 4 and 6 weeks. However, even if patients take the ELISA test and receive a negative result, they are recommended to redo the test 3 months (after exposure) to confirm they are HIV free.
What prophylaxis should be given to patients with HIV and why?
All patients with a CD4 count lower than 200/mm3 should receive prophylaxis against Pneumocystis jiroveci pneumonia
Important for meLess important
All patients with a CD4 count lower than 200 cells/mm³ should receive prophylaxis against Pneumocystis jirovecii pneumonia.
Aciclovir is sometimes used as longterm herpes suppression treatment in patients with both HIV and HSV.
How do treated cellulitis in pregnancy?
The BNF recommends flucloxacillin as first-line treatment for mild/moderate cellulitis. Clarithromycin, erythromycin (in pregnancy) or doxycyline is recommended in patients allergic to penicillin.
NICE recommend that patients severe cellulitis should be offered co-amoxiclav, cefuroxime, clindamycin or ceftriaxone.
How can gonorrhoea be treated?
For patients with gonorrhoea, a combination of oral cefixime + oral azithromycin is used if the patient refuses IM ceftriaxone
Important for meLess important
NICE guidelines advise that patients with a positive gonorrhoea test should be referred to a sexual health clinic for management and follow up.
The first-line treatment is a single dose of IM ceftriaxone.
