Infectious Disease Flashcards by Scott Griffiths

Organisms splenectomy patients are at risk from

pneumococcus, haemophilus, meningococcus and Capnocytophaga canimorsus (usually from dog bites)

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splenectomy vaccinations needed and prophylactic Abx

Hib,
meningitis A and C
annual influenza
pneumococcal vaccine every 5 yrs

penicillin V

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Leishmaniasis - type of organism involved, mode of spread, forms of the disease

intracellular protazoa
sand fly
cutaneous (mexicana)
mucocutaneous (brasiliensis)
visceral (donovani)

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multiple ring enhancing lesions seen on CT of HIV+ pt. Dx? Mx?

toxoplasmosis
most common neurological infection in HIV pts
Mx - pyrimethamine and sulfadiazine

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features of severe malaria

schizonts on blood film
temp >39
parasitaemia >2%
severe anaemia
hypoglycaemia
cerebral malaria - seizures, coma
acute renal failure
ARDS
DIC

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main organism responsible for bacterial vaginosis

gardnerella vaginosis (anaerobic)

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Mx of bacterial vaginosis

oral metronidazole for 5-7 days,
more than half relapse in 3 months
topical metronidazole or clindamycin as alternatives

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when do you start PCP prophylaxis in HIV pts?

when CD4 <200 (oral co-trimoxazole)

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Antibiotic therapies for meningitis:
at GP
hospital setting
hospital >50 and <3/12
pen allergic

IM benzylpenicillin - dont delay transport to hosp
IV cefotaxime
IV cefotaxime and amoxicillin
chloramphenicol

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Management of meningitis contacts

offer prophylaxis to close contacts and housemates
oral rifampicin or ciprofloxacin
offer vaccine afterwards.

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TB meds side effects
Rifampicin
Isoniazid
pyrazinamide
ethambutol

Rifampicin - hepatitis, flu-like Sx,
isoniazid - peripheral neuropathy, hepatitis, agranulocytosis, Pellagra (B3 def)
pyrazinamide - hyperuricaemia –> gout, hepatitis
ethambutol - optic neuritis - check VA before and during treatment.

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Listeria monocytogenes - typical spread, dangerous to who, management

multiply at low temperatures
typically spread via contaminated food
particularly dangerous to pregnant women - can lead to miscarriage
Mx: BCULT, Rx with amoxicillin/ampicillin

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Management of tetanus

supportative inc muscle relaxants
IM human tetanus immunoglobulin for high risk wounds
IV metronidazole

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symptoms of chlamydia

asymptomatic in 70% women and 50% of men

women: cervicitis (discharge, bleeding), dysuria
men: urethral discharge, dysuria

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Ix and Mx of chlamydia

nuclear acid amplification tests (NAATs) - 1st pass urine, vulvovaginal/cervical swab
7 days doxycycline or single dose azithromycin, erythromycin if preg.

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who do you contact if pt is found to have chlamydia

and what do you offer?

symptomatic men - partners in last 4 weeks
asymptomatic men and all women - partners from last 6 months
Test and treat prior to knowledge of results.

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most common cause of infective diarrhoea in HIV pts
Ix
Mx

cryptosporidium (protozoa)
acid fast stain shows red cysts
Supportative management

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what are the features of African trypanosomiasis (sleeping sickness)?
mode of spread?

trypanosoma chancre - painless nodule at site of infection
intermittent fever
posterior cervical chain LN enlargement
later CNS involvement - somnolence, headaches, meningoencephalitis

Tsetse fly

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whats is Chagas’ diease?

features

trypanosoma cruzi protozoa infection
95% asymptomatic in acute phase
chronic infection causes myocarditis (HF and arrhythmias) and megaoesophagus and megacolon (dysphagia and constipation)

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key features of:
trichomonas vaginalis
BV
candida

offensive yellow/green frothy discharge, vulvovaginitis

offensive thin grey fishy discharge

“cottage cheese” discharge, itchy

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what type of hypersensitivity occurs in scabies infections

type IV - delayed cell mediated response

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Mx of scabies infection

1st line: permethrin, repeat in 7 days
pruritis can persist for 4-6 weeks
treat all contacts and wash bed linen and towels on day 1

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features of Lyme disease
early
late

borrelia burgdorferi
early: erythema chronicum migrans (papule at site of tick bite -> annular lesion with central clearing)
systemic symptoms: malaise, fever, arthralgia

late:
cardio: myocarditis, heart block
neuro: CN palsies, meningitis
polyarthritis

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hep B serology seen in a previously infected pt (>6months ago)

anti HBs+ now immune. negative in chronic disease
anti HBc+ positive in current or previous infection
HBsAg - no current infection and not infectious (positive in HB carriers)

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what is the cause of typhoid and paratyphoid?

salmonella typhi and paratyphi (types A, B &C)

features of typhoid

systemic upset: fever, arthralgia, h/a relative bradycardia abdo pain, distention, constipation Rose spots are pathognomonic (blanching pink, macular 2-3mm on trunk)

features of Brucellosis how is it Dx? Mx?

malaise and fever, hepatosplenomegaly, sacroiliitis brucella serology test doxy and streptomycin

what is the organism that causes syphilis

treponema pallidum

mode of action of aciclovir

inhibits viral DNA polymerase

``` target of the monoclonal antibodies: rituximab infliximab trastuzumab cetuximab ```

rituximab - anti CD20 (Non-hodgkin's and RA) infliximab - anti TNF (RA and Crohns) trastuzumab (Herceptin) - anti HER2 (breast ca) cetuximab - epidermal GFr antagonist (met colorectal ca and h&n ca)

Mx of trypanosomiasis?

Early: IV pentamidine or surine | If CNS involvement: melarsoprol

what is the microscopic structure of gonorrhoea

gram negative diplococci

what percentage of men and women are symptomatic with gonorrhoea?

90-95% of men | 50% of women

what is the Ix and Mx of gonorrhoea?

1st past urine NAAT (nuclear acid amplification test) | Mx IM ceftriaxone 500mg and azithromycin 1g PO, contact tracing, retest in 2 weeks.

What contact tracing is needed for gonorrhoea?

symptomatic - sexual partners from last 2 weeks | asymptomatic - 3 months

What is the most common STI

chlamydia, 2nd gonorrhoea.

what percentage of men and women are symptomatic with chlamydia?

men 50% | women 20%

complications of chlamydia

men: epididymitis, epididymo-orchitis women: PID, tubal infertility, ectopic pregnancy

Mx of chlamydia

single dose 1g azithromycin (erythromycin if preg) or 7 days 100mg doxycycline

Ix and Mx of lyme disease

serology tests for antibodies to Borrelia burgdorferi Mx: doxy if early, ceftriaxone if disseminated Can have Jarish-Herxheimer reaction after starting Rx - fever rash tachy. also seen in syphillis.

features and Mx of cutaneous anthrax

black eschar, marked oedema, typically painless and non tender Mx:ciprofloxacin

gram positive cocci

staph and strep (including entero)

gram negative cocci

N.meningitis, N.gonorrhoea, moraxella

what medication do you give for malaria prophylaxis?

atovaquone + proguanil (Malarone)

risk of Hep B infection from needlestick of Hep B infected pt Mx

20-30% if had vaccine, give booster, if not had vaccine - Hep B IG and vaccine

Treatment of shigella

ciprofloxacin

features of Dengue fever | Mx

h/a, fever, low platelets, raised ALT Mx: symptomatic

Mx of toxoplasmosis in HIV patients

treat if CD4 count is <200 | sulfadiazine and pyrimethamine

Ix for malaria

3 x blood films raised platelets normochromic normocytic anaemia normal WCC

Features of loiasis

painful swellings of the limbs - angioedema with paraesthesia leukocytosis and hypereosinophilia conjunctival spread (eye worm) Filarial infection caused by Loa Loa (central and western Africa)

prevention of loiasis

weekly diethylcarbamazine citrate for prevention

Most common skin condition in HIV pts

Eosinophilic folliculitis Occurs when CD4 <300 Itchy papules and pustules on chest and arms

Organism, symptoms and treatment of schistosomiasis

Schistosoma Haematobium dysuria, frequency, haematuria (occasionally haemospermia), incontinence Rx: oral praziquantel

Features of HIV seroconversion illness | Ix

fever, malaise, arthritis rash, sore throat diarrhoea, lymphadenopathy meningo-encephalaitis Seroconversion period 2-3 weeks to 3 months. Ix: P24 antigen and HIV RNA PCR.

Amoebic dysentry: features Ix Mx

fever (rarely high temps) abdo pain and diarrhoea. Stool may have blood or mucus in. Ix: stool cultures and microscopy Mx: oral metronidazole for 5 days then diloxanide furoate to destroy gut cysts.

Mx of hookworm

Most common feature is iron deficiency anaemia | Mx with albendazole or mebendazole (antihelmintic)

Inhibit cell wall formation Abx

penicillins | cephalosporins

Inhibit protein synthesis Abx

``` aminoglycosides (cause misreading of mRNA) chloramphenicol macrolides (e.g. erythromycin) tetracyclines fusidic acid ```

Inhibit DNA synthesis abx

quinolones (e.g. ciprofloxacin) metronidazole sulphonamides trimethoprim

Inhibit RNA synthesis abx

rifampicin