Infectious disease Flashcards
Give an example of Group A strep?
strep pyogenes
What does strep pyogenes cause?
erysipelas impetigo cellulitis T2 necrotising fasciitis pharyngitis tonsilitis
What causes type 1 and 2 necrotising fasciitis?
T1: clostridium perfringens
T2: streptococcus pyogenes
What immunological reactions can group A strep cause?
rheumatic fever
post strep glomerulonephritis
Symptoms of P.falciparum?
cyclical fever (every 48h) splenomegaly neurological involvement-> altered GCS and seizures D&V metabolic acidosis shock
P.falciparum findings on blood film?
ring trophozoites
crescent shaped gametocytes
mauer’s clefts
double dotted rings
P.falciparum treatment?
mild: oral macaroni
severe: IV artesunate, hypoglycaemia management, hydrate cautiously
monitior parasitaemia
P.vivax findings on blood film?
schaffners dots
P.ovale findings on blood film?
enlarged red cells
comet forms
P.malariae findings on blood film?
daisy head appearance
square ring forms
Mx for p.vivax, ovale and malariae?
chloroquine
Where is vivax found?
South america and asia
Where is falciparum found?
africa
symptoms for p.vivax, ovale and malariae?
indolent up to a year to start to have symptoms, esp vivax
vivax/ovale cyclical fever 48h
malariae cyclical fever 72h
Ix for malaria?
3 thick and thin blood films (thick = parasite, thin = species)
Look for parasitaemia
malaria rapid antigen detection tests (plasmodial HRP-II, parasite LDH)
prevention of malaria?
anti-malarial prophylaxis with quinine
bite prevention - repellentandents
when to admit someone with malaria?
severe/complicated malaria falciparum malaria child pregnant >=65yo
Malaria Mx?
variable
non-falciparum: chloroquinine
mild falciparum (not vomiting, parasitaemia <2% and ambulant): artemisinin combination therapy/atovaquone-proguanil or quinine + doxy
severe: IV artesunate/IV quinine
what causes typhoid?
salmonella typhi or paratyphoid
complications of typhoid?
GI perforation
myocarditis
hepatitis
nephritis
S/S typhoid ?
Fever + bradycardia anorexia (WL +++) GI: diarrhoea or constipation cough malaise, myalgia headache
SPLENOMEGALY, bradycardia, trunk ROSE SPOTS
what is sphygmo thermal dissociation?
fever + bradycardia
Ix typhoid?
blood culture [diagnostic]
other - FBC, LFT, stool
Mx typhoid?
IV ceftriaxone OR IV cefotaxime
2nd: azithromycin
what causes dengue?
Aedes aegyptii mosquito
usually SE asia and S.Africa
incubation of dengue?
short (5 days)
if loner consider HIV seroconversion
S/S dengue?
low WCC, low platelets, low Hb Headache (retro-orbital) sunburn like rash high fever and myalgia hepatomegaly, abdominal distension
What is dengue haemorrhagic fever?
secondary infection with different strain
- severe capillary leak, hypotension, haemorrhagic manifestations
Ix dengue?
gold standard is PCR viral antigen, serology IgM
FBC, LFTs, serum albumin
Mx dengue?
supportive
ITU
What causes Q Fever?
coxiella burnetii
Q fever transmission?
goats, sheep, cattle, milker aerosols
S/S Q fever?
fever, pneumonia, abscess
Ix Q fever?
serology
Mx Q fever ?
doxycycline
Brucellosis transmission?
goats, sheep, cattle, milk, meat, aerosols
S/S brucellosis?
fever
back pain
orchitis
abscess
Mx brucellosis?
doxycycline + gent/rifampicin
Lyme disease is caused by?
borrelia burgdorferi
ixodes tick
Stages of lyme disease
rash -> malaise carditis,meningitis -> CNS signs
S/S lyme disease?
fever
erythema chronicum migrans (bulls eye rash)
Mx lyme disease?
doxycycline
amoxicillin if doxy CI (e.g. pregnancy)
What causes leptospirosis?
L.interrogans (gram -ve spirochete)
transmitted by farm animals, contaminated water and RAT URINE
S/S leptospirosis?
fever, constitutional, ARF, jaundice, UVEITIS, high fever, bilateral calf pain
Ix leptospirosis
serology
Mx leptospirosis
doxycycline
Cause of anthrax?
bacillus anthraces
transmitted by cows
S/S anthrax
pulmonary sings, cutaneous (eschar)
GI signs
Ix anthrax
PCR
mX Anthrax
Doxycycline
what causes leishmania?
unicellular protozoa (vector: sand fly)
Ix leishmania?
culture (NMN medium)
nil mx
Types of leishmania?
visceral
cutaneous
mucocutaneous
what causes sleeping sickness?
trypanosoma
flagellate unicellular protozoan (vector tsetse fly)
S/S trypanosoma?
fever, sleep disturbance, CNS
Features of chagas disease?
caused by T.cruzii
Brazil
acute = purple eyelids
chronic = achalasia
Where should swabs for chlamydia and gonorrhoea in women be taken from?
vulvo-vaginal area (introitus)
what is the most sensitive and specific test for the diagnosis of Chlamydia in females?
NAAT
features of chlamydia?
asymptomatic in around 70% of women and 50% of men
women: cervicitis (discharge, bleeding), dysuria
men: urethral discharge, dysuria
complications of chlamydia?
epididymitis
pelvic inflammatory disease
endometritis
increased incidence of ectopic pregnancies
infertility
reactive arthritis
perihepatitis (Fitz-Hugh-Curtis syndrome)
Ix Chlamydia?
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
What is seen on PAP smear for chlamydia?
infected endocervical cells
red inclusion bodies
Mx chlamydia
doxycycline (7 day course) if first-line
doxycycline is contraindicated / not tolerated: azithromycin (1g od for one day, then 500mg od for two days)
if pregnant: azithromycin, erythromycin or amoxicillin
PARTNER NOTIFICATION:
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
what is first line management for onychomycosis
terbinafine - nhibits the fungal enzyme squalene epoxidase, causing cellular death
what causes giardiasis?
Giardiasis is caused by the flagellate protozoan Giardia lamblia. It is spread by the faeco-oral route.
RF giardiasis?
foreign travel
swimming/drinking water from a river or lake
male-male sexual contact
Features giardiasis?
often asymptomatic lethargy, bloating, abdominal pain flatulence non-bloody diarrhoea steatorrhoea chronic diarrhoea, malabsorption and lactose intolerance can occur
Ix and mx giardiasis??
stool microscopy for trophozoite and cysts: sensitivity of around 65%
stool antigen detection assay: greater sensitivity and faster turn-around time than conventional stool microscopy methods
PCR assays are also being developed
Treatment is with metronidazole.
which Abx are currently used for MRSA infection?
vancomycin
teicoplanin
linezolid
Mx Chagas?
acute phase: azole or nitroderivatives such as benznidazole or nifurtimox
chronic disease management involves treating the complications e.g., heart failure
what is trichomonas?
Trichomonas vaginalis is a highly motile, flagellated protozoan parasite. Trichomoniasis is a sexually transmitted infection (STI).
what are the features of trichomonas?
vaginal discharge: offensive, yellow/green, frothy
vulvovaginitis
strawberry cervix
pH > 4.5
in men is usually asymptomatic but may cause urethritis
investigation of trichomonas?
microscopy of a wet mount shows motile trophozoites
management of trichomonas?
oral metronidazole for 5-7 days, although the BNF also supports the use of a one-off dose of 2g metronidazole
what should all patients with a CD4 count lower than 200/mm3 receive?
prophylactic co-trimoxazole, to cover against Pneumocystis jiroveci pneumonia
HAART
What are the features of mycoplasma pneumonia?
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
What are the complications of mycoplasma pneumoniae?
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
Ix mycoplasma?
diagnosis is generally by Mycoplasma serology
positive cold agglutination test
Mx mycoplasma?
doxycycline or a macrolide (e.g. erythromycin/clarithromycin)
S/S mycoplasma?
longer duration of symptoms and unusual features of abdominal pain, dry cough and hyponatraemia
Ix Lyme disease
May be diagnosed clinically if erythema migraines present
Enzyme-linked immunosorbent assay (ELISA) antibodies to Borrelia burgdorferi are the first-line test
what complication may be seen after initiation of therapy in lyme disease?
Jarisch-Herxheimer reaction is sometimes seen after initiating therapy: fever, rash, tachycardia after first dose of antibiotic (more commonly seen in syphilis, another spirochaetal diseas
What is infectious mononucleosis caused by?
most common: Epstein-Barr virus (EBV, also known as human herpesvirus 4, HHV-4) (90% of cases)
less common: cytomegalovirus and HHV-6
What are the symptoms of infectious mononucleosis?
classic triad of sore throat, pyrexia and lymphadenopathy
splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
hepatitis, transient rise in ALT
lymphocytosis: presence of 50% lymphocytes with at least 10% atypical lymphocytes
haemolytic anaemia secondary to cold agglutins (IgM)
Ix infectious mononucleosis?
heterophil antibody test (Monospot test) - NICE guidelines suggest FBC and Monospot in the 2nd week of the illness to confirm a diagnosis of glandular fever.
Mx infectious mononucleosis?
rest during the early stages, drink plenty of fluid, avoid alcohol
simple analgesia for any aches or pains
consensus guidance in the UK is to avoid playing contact sports for 4 weeks after having glandular fever to reduce the risk of splenic rupture
Mx gonorrhoea?
IM ceftriaxone
Mx PID?
Doxycycline + metronidazole + ceftriaxone
When should IV dexamethasone be avoided in meningitis?
septic shock
meningococcal septicaemia
immunocompromised
meningitis following surgery
Mx trichomonas?
Metronidazole
Mx pubic lice?
Malathion
Mx of Chlamydia in pregnancy?
Azithromycin, erythromycin or amoxicillin
Mx of syphilis?
IM benzathine penicillin
patients are advised to be retested for syphilis at 6, 12 and 24 months to confirm that treatment has worked
If you have successfully been treated for syphilis what test results would you expect to see?
negative non-treponemal test + positive treponemal test
example of non-treponemal test?
Rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL)
based upon the reactivity of serum from infected patients to a cardiolipin-cholesterol-lecithin antigen
assesses the quantity of antibodies being produced
becomes negative after treatment
Example of treponemal test?
TP-EIA (T. pallidum enzyme immunoassay), TPHA (T. pallidum HaemAgglutination test)
the TP-EIA test has become increasingly popular in recent years
specific for syphilis (antibodies to T pallidum)
Which antibiotic should be used for meningitis if the patient has a history of allergy to penicillin/cephalosporins?
chloramphenicol
What are the features of campylobacter?
gram -ve
prodrome: headache malaise
diarrhoea: often bloody
abdominal pain: may mimic appendicitis
Management of campylobacter?
usually self-limiting
the BNF advises treatment if severe or the patient is immunocompromised.
antibiotics if severe symptoms (high fever, bloody diarrhoea, or more than eight stools per day) or symptoms have last more than one week
the first-line antibiotic is clarithromycin
ciprofloxacin is an alternative
Complications of campylobacter?
Guillain-Barre syndrome may follow Campylobacter jejuni infections
reactive arthritis
septicaemia, endocarditis, arthritis
What are Amsel’s criteria for BV?
3/4 need to be present:
thin, white homogenous discharge
clue cells on microscopy: stippled vaginal epithelial cells
vaginal pH > 4.5
positive whiff test (addition of potassium hydroxide results in fishy odour)
Management of BV?
oral metronidazole for 5-7 days
70-80% initial cure rate
relapse rate > 50% within 3 months
the BNF suggests topical metronidazole or topical clindamycin as alternatives
When should you do an urgent referral for haematuria?
Aged >= 45 years AND:
- unexplained visible haematuria without urinary tract infection, or
- visible haematuria that persists or recurs after successful treatment of urinary tract infection
Aged >= 60 years AND have unexplained nonvisible haematuria and either dysuria or a raised white cell count on a blood test
which factors offer protection from malaria?
G6PD deficiency
HLA-B53
absence of Duffy antigens
Give an example regime for renal transplant immunosuppression?
initial: ciclosporin/tacrolimus with a monoclonal antibody
maintenance: ciclosporin/tacrolimus with MMF or sirolimus
add steroids if more than one steroid responsive acute rejection episode
What is recommended for all HIV patients with a CD4 count lower than 200/mm3?
prophylaxis against Pneumocystis jiroveci pneumonia
co-trimoxazole
CD4+ T lymphocyte cell count <200/mm³ indicates immunodeficiency
What are the four types of solid organ transplant rejection?
- Hyperacute rejection
- Acute antibody-mediated rejection
- Acute T-cell mediated rejection (most common)
- Chronic rejection
What are the criteria for diagnosing AKI?
↑ creatinine > 26µmol/L in 48 hours
↑ creatinine > 50% in 7 days
↓ urine output < 0.5ml/kg/hr for more than 6 hours
Primary features of syphilis?
chancre - painless ulcer at the site of sexual contact
local non-tender lymphadenopathy
often not seen in women (the lesion may be on the cervix)
Secondary features of syphilis?
occurs 6-10 weeks after primary infection
systemic symptoms: fevers, lymphadenopathy
rash on trunk, palms and soles
buccal ‘snail track’ ulcers (30%)
condylomata lata (painless, warty lesions on the genitalia)
Tertiary features of syphilis?
gummas (granulomatous lesions of the skin and bones) ascending aortic aneurysms general paralysis of the insane tabes dorsalis Argyll-Robertson pupil
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
What features of characteristic of an infection with Clostridium botulinum
patient usually fully conscious with no sensory disturbance flaccid paralysis - descending diplopia ataxia bulbar palsy
what is Fitz-Hugh Curtis?
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.
Triad of disseminated gonococcal infection?
tenosynovitis, migratory polyarthritis, dermatitis
Neisseria gonorrhoea ->gram-ve diplococcus
Features of gonorrhoea?
males: urethral discharge, dysuria
females: cervicitis e.g. leading to vaginal discharge
rectal and pharyngeal infection is usually asymptomatic
Complications of gonorrhoea?
urethral strictures
epididymitis
salpingitis (hence may lead to infertility)
disseminated infection
Mx gonorrhoea?
IM ceftriaxone 1g (i.e. no longer add azithromycin)
If sensitive to ciprofloxacin) then a single dose of oral ciprofloxacin 500mg should be given
If needle phobic: oral cefixime 400mg (single dose) + oral azithromycin 2g (single dose)
What is the most common cause of septic arthritis in young adults?
gonococcal infection
treatment of genital warts?
multiple, non-keratinised warts: topical podophyllum
solitary, keratinised warts: cryotherapy
