infectious diseases Flashcards
usually has a prodrome pain before the vesicles appear. It usually follows a particular dermatome but in immune suppression the disease may affect more than one dermatome.
Herpes zoster aka varicella zoster virus
vesicles may appear but they never follow a particular dermatome.
herpes simplex
presence of scabs around the groin or any other fold
tinea inguinales
This appears like a burn. It appears as bullae which eventually burst. It could be generalised.
strep scalded skin syndrome
could sometimes appear as streptococcal scalded skin syndrome, but there are more likely to be pustules.
staph a
drop-like, fir-tree puritic lesion following sore throat
guttate psoriasis
a papulosquamous disorder of unknown aetiology which presents as red-orange plaques. It is a cause of erythroderma.
Pityriasis rubra pilaris
Pityriasis rosea
Pityriasis rosea is of unknown aetiology and is a widespread pink patchy rash that appears after a ‘herald patch’.
Causes of erythema multiforme
Herpes simplex virus infection is the commonest cause. Other common causes include infection with Mycoplasma and Streptococci.
EM may also:
Be idiopathic
Be drug-induced (sulfonamides, sulphonylureas, barbiturates)
Occur in systemic diseases (SLE, inflammatory bowel disease, malignancy).
features of PCP
Several days/weeks of increasing dyspnoea
Dry cough
Marked oxygen desaturation with exercise.
Signs of immunocompromise
Clear CXR
bilaeral crackles
severe exfoliative disease with mucus membran involvement
TEN is a severe mucocutaneous exfoliative disease with an uncertain pathogenesis and a high mortality rate.
It is difficult to say whether it is another variant of Stevens-Johnson syndrome and treatment of both are similar.
It is often idiopathic but may be associated with:
Viral infections
Leukaemia
Lymphoma, and
Drugs (in particular sulphonamides and anticonvulsants).
treatment for samonella typhi
ciprofloxacin
disseminated gonoccal infection
septic arthritis, arthralgia, endocarditis, meningitis, and fevers.
signs of epididymitis
recurrent UTIs
The presence of long term catheters, underlying urinary tract pathology or recent instrumentation are risk factors for epididymitis.
The most common pathogens in men over the age of 35 are coliforms and Pseudomonas.
immediate management is to commence empirical antibiotics which cover Gram positive and negative organisms while awaiting urinary cultures, scrotal elevation, bed rest, and analgesia.
Timing of BCs in IE
Draw three samples of blood from different venepuncture sites with the first separated from the last by at least one hour over 24 hours
Diarrhoea Abdominal pain Flatulence Nausea Anorexia, and Weight loss. Travel
Giardia lambia
contaminated water
rx:metronidazole
scabies treatment
permethrin cream, topical benzyl benzoate, and malathion
Treated gonorrhoes, ongoing urethritis
treat for chlamydua trachomatis/non-specific urethitis
Gonorrhoea is one of the commonest reported STDs in both men and women. In men the symptoms manifest as urethritis and in women cervicitis or urethritis. gram negative intracellular Diplococci
More commonly patients present with co-infection with Chlamydia trachomatis, requiring treatment with either pencillin (ceftriaxone 250mg IM) doxycycline or erythromycin for 7-14 days.
ventilator associated pnemonia
haemophilis influenza (gram -ve bacilli) strptotrphmona maltophilia, rare cause
urethritis, conjunctivitis, arthritis
Reactive arthritis
Disseminated gonoccoal infection, gram negative intracellular diplococci
treat with ceftriaxone and azithromycin
neutrophillic CSF/ meningitis and immunocompromise
Bacterial infections such as listeria monocytogenes
Treat with ampicillin and genatmicin
Neutrophils (polymorphonuclear, leukocytes containing granules that are released during infection e.g. neutrophils, basphils, eosinophils - granulocytes) presdominated in CSF of bacterial meningitis. However TB and gunal lymphocytic (t/B cells predominate)
Marker of hepatitis B infection
Anti HBc is present throughout infection
Anti HBc IgM antiboody : acute infectoin
Anti HBc IgG and anti-HBs = recovering from infection
Anti HBc and HBsAg = chronic infection
HBe antigen is a marker of infectivity
treatment for c diff
oral metronidazole, oral vanc is an alternative
side effects of AZT
bone marrow suppresion causing macrocytic anemia
Other side-effects of zidovudine include:
Myalgia Myopathy Myositis Pancytopenia, and Lactic acidosis. Blue discolouration of the nails is a rare side-effect.
Macrocytosis is a typical finding in patients on AZT and can be used as a parameter to monitor adherence to therapy.
endemic in sheep farming regions. Asymptomatic, calcified cystic lesions in the liver
Varicella pneumonia occurs in up to 20% of adults with chickenpox, appearing three to five days into the course of the illness. In adults with pneumonitis, treatment with aciclovir is warranted. what are the symptoms?
Cyanosis, pleuritic chest pain and haemoptysis are common.
In adults with pneumonitis, treatment with aciclovir is warranted.
meningitis prophylaxis
ciprofloxacin
green colouration of the colonies
psudomonas aerginosa
production of the pigment pyocyanin.
consistent with a diagnosis of cystic fibrosis; bronchiectasis associated with CF frequently results in recurrent infections with Pseudomonas.
treatment of CAP
low curb: doxycyline
high curb: IV co-amox and clari
pen allergy: cef and clari or teic
pnemonia, hemolytic anemia, erythema multiforme
mycoplasma pneumonia
Extrapulmonary manifestations of Mycoplasma occur in up to 10% of cases of Mycoplasma pneumonia. These include: • Haemolytic anaemia • Renal failure • Hepatitis • Myocarditis • Meningism and meningitis • Transverse myelitis, and Cerebellar ataxia.
Immunocompromised (HIV) and meningitis
India ink stain of CSF that shows typical yeast-like forms
cryptococcus
neurology (seizures, meningism), fever, background of sinusitis, ring enhancing lesion on CT
bacterial CSF
pyogenic brain abscess
other ring enhancing lesions:
- toxoplasmosis (also presents like EBV)
- TB/histoplasmosis (also has chest symptoms)
live vaccine in immunocompromised
yellow fever
Clue cells on saline wet mount
BV
atrophic vaginosis are characterised by dyspareunia and inflammation
Tichomoniasis
what is Enterobius vermicularis
threadword
Transmission is by the faeco-oral route and intense anal pruritus is the predominant symptom. Treatment is with mebendazole.
what is Hymenolepis nana
rodent cestode parasite that can be transmitted to humans and usually affects children. Abdominal pain, anorexia, diarrhoea, pruritus ani and urticaria are the most frequent symptoms. Eosinophilia may be present in heavy infestations. Treatment is with praziquantel.
what is ecchonus granulosus
responsible for hyatid
what is trichuriasis
Trichuriasis is commoner in malnourished populations; symptoms are minimal but may result in growth retardation in children. Heavy burdens of infection may be associated with bloody diarrhoea; it is associated with rectal prolapse. Treatment is with mebendazole.
Haemophilus ducreyi and presents with painful lymphadeonapthy and erythematous papules.
chancroid
Gram negative rod
pustules breakdown to haemorrhagic ulcers
single painless ulcer and inguinal lymphadenopathy
lymphogranuloma venereum however LGV initially presents as a single painless ulcer with secondary infection occurring two to six weeks later.
multiple indolent painful ulcer
Granuloma inguinale is caused by Klebsiella granulomatos also know as donoviasis. Regional lymphadenopathy is rare. The incubation period is one to three months.
gram positive catalase negative
streptococcus
staph is catalase positive
What is the basis of methicillin resistance in Staphylococci?
the bacteria modify the penicillin-binding protein so that they have a low affinity for beta-lactamase antibiotcis, pseudomonas and enterococcus do the same
what is brucella melitensis
causes brucellosis
- fever, arthralgia, abnormal liver function tests, and coccobacilli on blood culture
- Untreated patients may be symptomatic for months, with localisation of the disease to the brain, genitourinary tract, liver and heart.
- Treatment is with doxycycline and a second agent such as gentamicin or rifampicin.
motile flagellated protozoa, yellow discharg, strawberry cervix
trichmonas vaginalis
rx: metronidazole
management of neuroschistosomiasis
neuroschistosomiasis is secondary to hypersensitivity reactions there is need to use a steroid, in this case prednisolone 1 mg/kg per day.
Praziquantel 60 mg/kg per day for six days is recommend for S. japonicum
post oragan transplant, leukopenia, fever, dyspnoea
CMV Infection
treatment fro staph a IE
IV gent and vanc
treatment for strep IE
IV benpen and gent
what is severe PCP and management
PO2 < 9
Co-trimoxazole or IV pentamidine/clindamycin with primaquine (if allergic)
and Steroids
Treatment for suspected TB meningitis
Start ceftriaxone (bacterial meningitis), RIPE and dexamthasone
Treatment for varicella zoster in immunocompromised
IV aciclovir TDS 10mg/kg
e.europe, russia, asia sore throat, grey membrane on tonsils cervical lymphadenopathy neuritis heart block
Diptheria
gram positive
necrotic black eschar painless, non-tender spread by infected carcasses marked oedema GI bleeding
Anthra
Bacilus anthracis, gram positive rod
Norcardia
similar to actinomyces, fungud like
gram +ve rod
sulhur granules
pneumonia and brain abscess in immunocompromised
TB meningitis treatment
RIPE and dexamethasone
actinomyces
gram positive rod, fungus like hyphae sulphur granule masses spreads through mucosa, forms oral/throat abscesses abdo mass RIF multiple sinus tracts occurs in those with appendicitis
RX: long term penicillin, surgical resection
Cryptococcus meningo-encephalitis
Cryptococcus meningo-encephalitis. The causative organism is Cryptococcus neoformans, a fungus which causes severe infection in patients with defective cell-mediated immunity.
This is an AIDS-defining illness which typically occurs when the CD4 count is less than or below 100. Symptoms are typically of gradual onset over one to two weeks. Diagnosis is by examination of CSF with India ink. This will demonstrate typical encapsulated yeast forms.
Treatment regimes include the use of IV amphotericin B, to which flucytosine is sometimes added. In certain instances a long course of fluconazole may be used.
Trichuris trichiura
Trichuris trichiura (whipworm) is a helminth approximately 4 cm in length. Infected patients are largely asymptomatic.
hookworms
Necator americanus and Ancylostoma duodenale are hookworms (~1 cm in length). The major manifestation of chronic disease is iron-deficiency anaemia.
nematode
Strongyloides stercoralis is a nematode infection. Symptoms may be cutaneous (pruritus due to invasion by the nematodes), pulmonary (eosinophilic pneumonia due to passage through the lungs) or gastrointestinal (abdominal pain).
Ascaris lumbricoides is a large roundworm, growing up to 35 cm in length, and is the most common nematode parasite of humans. Infected patients are often asymptomatic. Symptoms may develop as a result of pneumonitis caused by the worm’s migration through the lungs, obstruction of the gastrointestinal tract or biliary/pancreatic duct obstruction. Piperazine is the treatment of choice in patients presenting with bowel obstruction; mebendazole may be used to treat other infections.
Ascaris lumbricoides is a large roundworm, growing up to 35 cm in length, and is the most common nematode parasite of humans. Infected patients are often asymptomatic. Symptoms may develop as a result of pneumonitis caused by the worm’s migration through the lungs, obstruction of the gastrointestinal tract or biliary/pancreatic duct obstruction. Piperazine is the treatment of choice in patients presenting with bowel obstruction; mebendazole may be used to treat other infections.
fish-tank granuloma
fish-tank granuloma, caused by the atypical mycobacterium, Mycobacterium marinum. It is found in ornamental fish and is commonly seen in individuals who rear fish as a hobby.
Cryptococcal meningitis
Diagnosis is by demonstration of C. neoformans in the cerebrospinal fluid, shown on an India ink stain: the thick polysaccharide capsule is highlighted around the cell (shown in slide).
Cryptococcal meningitis is an AIDS-defining illness occurring when CD4 less than 50 cells/mm3 and may be associated with a pneumonitis.
Cryptococcus can also cause papular skin lesions that resemble molluscum contagiosum.
The disease is commoner in African populations.
weever fish sting
The weeverfish (Trachinus vipera) lives in shallow waters around the coast of the United Kingdom.
This small, sandy-coloured fish has sharp dorsal opercular spines that are attached to subcutaneous poison glands. Most stings from the weeverfish occur in the summer months in bare-footed bathers who step on the fish in shallow water, but stings also occur in anglers who attempt to grasp the fish when caught on a line.
The sting of the fish causes intense pain at the site of the wound. The toxin produced by the fish is heat-labile and is denatured at temperatures above 40°C. Treatment of a weeverfish sting should include cleansing of the wound and immersion in hot water (as hot as can be borne), ideally around 45°C.
acute rubella serology
A positive rubella haemagglutination inhibition (HAI) combined with a negative rubella IgM is consistent with:
Early acute infection with rubella
Previous vaccination, or
Previous rubella infection.
The most important issue to resolve is whether she has acute rubella.
The IgM may take several days to rise and the test should be repeated one to two weeks later.
treatment of nuetropenic sepsis with indwelling central line
Initial empiric antibiotic therapy for patients with suspected neutropenic sepsis with indwelling central venous access devices includes Tazocin, Gentamicin and Vancomycin.
chronic treatment of lithium toxicity
Lithium toxicity is more common when renal excretion of lithium is reduced, for example, concomitant use of diuretics or non-steroidal anti-inflammatory drugs (NSAIDs), or dehydration.
Cardiovascular adverse effects are more likely to occur in the presence of underlying cardiac disease.
In acute or chronic toxicity, a lithium level of greater than 4 mmol/L or features of central nervous system toxicity or cardiac instability are indications for haemodialysis.
Whole bowel irrigation should be considered in adults who have ingested a slow release preparation of lithium of greater than 4 g.
botulism
descending progressive weakness. There is cranial nerve involvement affecting ocular movements, swallowing, and facial musculature. There is also weakness of neck extension and intercostals as evidenced by reduced chest expansion. In addition she complains of autonomic features such as vomiting, abdominal pain and dry mouth.
This combination of signs and symptoms are in keeping with botulism.
Botulism is caused by a neurotoxin produced by Clostridium botulinum (CB). The toxin binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions. Toxin binding blocks acetylcholine release, resulting in weakness, flaccid paralysis, and (often) respiratory arrest.
Botulism can be food-borne or develop from wound infection (the likely source in this woman’s case from intravenous drug injection). Botulism can cause a false positive tensilon test result.
HAART regime
HAART typically consists of a regime of three or more antiretroviral agents of different classes.
A typical regime consists of two nucleoside analogues (for example, zidovudine [AZT], lamivudine [3TC]) and either a protease inhibitor (for example, nelfinavir, indinavir, ritonavir) or a non-nucleoside reverse transcriptase inhibitor (for example, nevirapine, efavirenz).
Antiretroviral therapies are frequent causes of anaemia in HIV-seropositive patients. Of these, zidovudine (AZT) is the agent that most frequently causes anaemia, usually by bone marrow suppression and patients can become transfusion-dependent in severe cases.
Macrocytosis is a typical finding in patients on AZT and can be used as a parameter to monitor adherence to therapy.
Scombroid poisoning
Scombroid poisoning is associated with consumption of Scombridae, dark meat fish such as tuna, mackerel and marlin.
The symptoms are due to ingestions of amines, predominantly histamines, produced by bacterial decarboxylation of histidine in fish meat. The most common cause of scombroid poisoning is due to ingestion of spoiled fish following inadequate refrigeration or prolonged time at room temperature. Cooking does not inactivate the toxin/histamines.
The illness is usually self-limiting and the severity is dependent on the amount of fish ingested, that is, symptoms are worse when a large amount of fish is ingested.
Onset is usually 10-30 minutes post-ingestion of the implicated fish but a delayed onset may occur up to two hours.
The symptoms that occur are typically associated with histamine such as
Headache Dizziness Abdominal pain Palpitations Nausea Diarrhoea Urticarial rash Bronchospasm and Hypotension or hypertension. Patients with pre-existing conditions such as bronchial asthma, and those taking isoniazid (a histaminase inhibitor) may be more symptomatic.
Specific treatment is usually unnecessary and most symptoms subside between two and 36 hours. In severe cases, symptoms respond rapidly to antihistamines, for example, chlorpheniramine and intravenous cimetidine by slow intravenous injection over at least five minutes.
red cysts on ZN stain stool sample
stool: modified Ziehl-Neelsen stain (acid-fast stain) of the stool may reveal the characteristic red cysts of Cryptosporidium
watery diarrhoea
abdominal cramps
fever
in immunocompromised patients the entire gastrointestinal tract may be affected resulting in complications such as sclerosing cholangitis and pancreatitis
HIV CNS infections
- SOLs - toxoplasmosis (multiple ring enhancing lesions), lymphoma (homogenous single lesion)
- Enephalitis (HIV, CMV)
- meningitis (cryptococcus - also has nerve palsies)
- PML - JC virus, periventricular lesions, demyelinating condition, behavioural changes
- dementia (AIDS/HIV complex)
HVZ and pregnancy
if asymptomatic test for antibodies
if -ve, PO aciclovir or immunoglobulins
Leptospirosis features
spirochaete, spread in faeces contaminated water
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
rx: doxy
PVL
Panton-Valentine Leukocidin is a pore-forming toxin which is produced by staphylococcus aureus. It has an affinity for white blood cells and the endothelium. Clinically PVL will often present with a necrotising pneumonia, characterised by severe bilateral pneumonia with cavitations on X-ray. Often patients presenting will have a history of boils or necrotic skin lesions. As the staphylococcus is easily transmitted there may be a recent family history of similar infections / boils.
Rx: linezolid
TB tretament
RIPE for 2 months, the RIP for 4 months
isoniazid resistant: RE for 6 months
RIPE SEs
Drug adverse effects
rifampicin
potent liver enzyme inducer
hepatitis, orange secretions
flu-like symptoms
isoniazid
peripheral neuropathy: prevent with pyridoxine (Vitamin B6)
hepatitis, agranulocytosis
liver enzyme inhibitor
pyrazinamide
hyperuricaemia causing gout
arthralgia, myalgia
hepatitis
ethambutol
optic neuritis: check visual acuity before and during treatment
typhus
samonella typhi or paratyphus, same features
spread by faecal-oral route
features:
- systemic sx
- constipation
- abdo pain
- bradycardia
- rose spots
complications
- meningitis
- bowel perf
- cholecystitis
- OM
cefotaxime/ceftriaxone
ESs of PIs
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
rickettsiae
rocky mountain - peripheral to central rash, north america
q fever - pneumonia
tropical scrub typhus - black eshar from tick bite
rx: tetracycline e.g. doxycycline
CMV presentations
neonatal/congential:
- features include growth retardation, pinpoint petechial ‘blueberry muffin’ skin lesions, microcephaly, sensorineural deafness, encephalitiis (seizures) and hepatosplenomegaly
immunocompetent:
- mononeucleosis: like EBV
immunocompromised e.g. HIV or organ transplant
- retinitis: cheesy pizza iv ganciclovir
- meningiti-pneumonitis
- colitis: CMV colitis with rectal and oesophageal involvement would explain the tenesmus, odynophagia, along with the bloody diarrhoea, abdominal cramps and weight loss.
infected cells have ‘owls eye’ appearance
schistosomiasis complications
s. haemaboticum: renal/bladder ca
s. mansoni/japonicum: block portal system = cirrhosis and varices
s intercalatum/maekonngi: Gi obstruction
