Infectious Diseases Flashcards
Which antibiotics have anti-anaerobic activity
Penicillins, cephalosporins (except ceftazidime), erythromycin, tetracycline, metronidazole
Which antibiotics have no anti-anaerobic activity
Ceftazidime, ciprofloxacin, gentamycin
What is the MOA of rifampicin
Prevents transcription of DNA to mRNA
What is the MOA of isoniazid
Inhibits mycolic acid synthesis
What is the MOA of pyrazinamide
Inhibits fatty acid synthase
What is the MOA of ethambutol
Inhibits arabinosyl transferase
What are the types of gram positive rods
Actinomyces, bacillus anthracis, clostridium, diphtheria, listeria
Which antibiotics inhibit cell wall formation
Penicillins, cephalosporins, isoniazid, vancomycin
Which antibiotic targets the 50s subunit of the ribosome
Macrolides (erythromycin, clarithromycin, azithromycin)
What is the MOA of tetracyclines
Inhibits 30s subunit of ribosome, thereby inhibiting protein synthesis
What drug must be stopped when macrolides are started
Statins
Which antibiotics inhibit DNA gyrase
Quinolones (ciprofloxacin, levofloxacin)
Which organism is responsible for most central line infections
Staph epidermis
Which organism is classified as group A beta-haemolytic streptococcus
Strep pyogenes
What is the diagnostic criteria for toxic shock syndrome
Temp >38.9, hypotension BP <90, diffuse erythematous rash, desquamation of palms and soles, >2 organs involved
What is the main organism that causes osteomyelitis in sickle cell patients
Salmonella
What is the main organism that causes necrotising fasciitis
Strep pyogenes
What is the treatment of anthrax
Ciprofloxacin
What are the main 3 organisms responsible for meningitis in adults
Neisseria meningitidis
Streptococcus pneumoniae
Listeria monocytogenes
Which organism spread by unpasteurised dairy can present with hemiparesis and ataxia
Listeria monocytogenes
What is the treatment of Lyme disease presenting with bulls eye lesions but no disseminated disease
Doxycycline 2-3 weeks
Which organism spread by infected rat urine causes renal failure in 50% and hepatic failure in 10% of cases
Leptospirosis
What is the gold standard investigation for diagnosing Brucellosis
Bone marrow aspiration and culture
How many mm is considered positive in Mantoux test
6mm
Name 5 causes of false negatives in Mantoux test
Miliary TB, HIV, sarcoid, immunosuppression, steroids
What is the treatment of TB meningitis
1 year TB treatment + steroids
What organism caught from fresh water produces ‘fish tank granulomas’
Mycobacterium marinum
What is the treatment of seizures caused by isoniazid
Vitamin B6 (pyridoxine)
How many strands of RNA are present in a HIV cell
2 copies of single stranded RNA
What are the envelope proteins present on HIV cells
GP120, GP41
What 3 main enzymes do HIV genes encode
Reverse transcriptase, integrase, protease
What does GP120 bind to on T cells to allow HIV to enter
CD4 and CXCR4
What does GP120 bind to on macrophages to allow HIV to enter
CD4, CCR5
What happens to IL-2 production in progressive HIV
IL-2 production decreases
Which vaccines are contraindicated in HIV
Cholera, intranasal influenza, oral polio, TB
What are the common suffixes to remember ARTs
Proteinase inhibitors = -navir
Integrase inhibitors = -gravir
Name 3 common NRTIs used for HIV treatment
Abacavir, tenofovir, zidovudine
What are the side effects of protease inhibitors
Diabetes, hyperlipidaemia, buffalo hump, central obesity, P450 inhibitors
What is the treatment of PJP
IV co-trimoxazole + IV methylprednisolone
What is the commonest causative organism of diarrhoea in HIV
Cryptosporidium
Which organism shows red rounded oocysts against blue-green background on acid-fast (Ziehl-Neelsen) stain of stool
Cryptosporidium
What two things cause Addison’s disease in HIV patients
CMV-Adenitis, TB
What is the most common fungal infection of the CNS in HIV
Cryptococcus
How is histoplasmosis diagnosed
Adrenal biopsy with groccott stain
What is the treatment of histoplasmosis
Itraconazole 3-6 months
How does the clostridium tetani neurotoxin act to cause lockjaw
Blocks release of GABA
What does the exotoxin produced by clostridium botulinum do to cause flaccid paralysis
Blocks ACh release
What does the shiga toxin act on
Inactivates 60S ribosome
Which bacteria release endotoxins
Gram negative e.g. Neisseria Meningitidis
Which virus can cause haemoptysis in HIV patients
HHV-8 (Kaposi’s sarcoma)
What is the most common cause of blindness in HIV
CMV retinitis
What is the MOA of acyclovir
Inhibits viral DNA polymerase
Which antiviral is used to treat CMV
Gancyclovir
Which antiviral used to treat chronic HCV interferes with capping of viral mRNA
Ribavarin
Which two conditions is amantadine used to treat
Influenza, Parkinson’s
What are the side effects of Foscarnet - an antiviral used to treat CMV and HSV
Nephrotoxic, low calcium, low magnesium
What is the MOA of interferon alpha in the treatment of HBV, HCV and hairy cell leukaemia
Inhibits synthesis of mRNA
Which virus in neonates causes skin scarring, eye defects, limb hypoplasia and microcephaly
VZV
When should Ramsay hunt syndrome be referred urgently to opthalmology
Vesicles on nasolabial folds or tip of nose
What is seen on blood film in EBV
At least 10% atypical lymphocytes
Which virus causes oral hairy leukoplakia
EBV
Which virus can lead to subacute sclerosing panencephalitis 5-10 years after exposure
Measles
Which virus causes Koplik spots
Measles
Which virus can cause aplastic crisis in sickle cell anaemia
Parvovirus B19
What condition is associated with aspirin exposure in children
Reye’s syndrome
What test is used to diagnose chlamydia
Nuclear acid amplification tests (NAAT)
What is the incubation of chlamydia
7-21 days
What is the treatment of chlamydia
Doxycycline
What is the incubation of gonorrhoea
2-5 days
What is the treatment of gonorrhoea
Ceftriaxone 1g IM single dose
What is the most likely organism seen in urethritis with purulent discharge
Gonorrhoea
Which condition presents with rash on trunk, palms and soles and buccal ‘snail track’ ulcers
Secondary syphillis
What are the symptoms of tertiary syphillis
Gummas (ulcerating skin lesions)
Aortic aneurysms, AR
Neurosyphillis
What are the symptoms of congenital syphillis
Blunted upper incisor teeth, saddle nose, deafness
Which organism causes Q fever
Coxiella burnetti
Which condition presents similarly to syphillis but is not sexually transmitted
Yaws
What is the name of the disease caused by haemophilus ducreyi that presents with painful ulcers
Chancroid
Which HPV is responsible for genital warts
6&11
Which condition is associated with clue cells
Bacterial vaginosis
Which STI is associated with strawberry cervix and raised vaginal pH
Trichomonas
What is seen on bloods in plasmodium falciparum
Schizonts on blood film Parasitaemia >2% Severe anaemia <50 Hypoglycaemia Metabolic acidosis Lactate >5
Which types of malaria cause a cyclical fever every 48 hours
Vivax and ovale
What is the most common type of malaria other than falciparum
Plasmodium vivax
What is the treatment of non-falciparum malaria
Chloroquine (+primaquine in ovale and vivax)
Which cancer is more likely to develop after schistosomiasis infection
Squamous cell bladder cancer
Which disease is spread by sand flies and causes grey skin in it’s visceral form
Leishmaniasis
Which organism causes mucocutaneous leishmaniasis (involving mucosa of nose and pharynx)
L. Brasiliensis
Which condition does the tsetse fly spread
African trypanosomiasis (sleeping sickness)
Which systems does trypanosoma cruzi affect
Chaga’s disease: cardiac (myositis), GI (dysphagia)
What intra-abdominal pathology can arise from tapeworm infection
Liver cysts leading to obstructive jaundice
What causes itching in scabies
Type IV hypersensitivity reaction to mites/eggs after 30 days
What is the treatment of scabies
Permethrin to patient and contacts
What organism causes cat scratch disease
Bartonella henselae
What is the treatment of pyogenic liver abscess
Amoxicillin + ciprofloxacin + metronidazole
What are the symptoms of tetanus
Jaw spasm, risus sardonicus, arched back, hyperextended neck, dysphagia
Which organism presents with fever, bradycardia, constipation and salmon-coloured rose spots
Salmonella typhi (typhoid)
What is the treatment of complicated Salmonella (Typhoid)
Ceftriaxone
How is giardia diagnosed
Duodenal aspirates or string tests
Which condition causes profuse rice water diarrhoea
Cholera
Which condition causes black spots on forearms/thighs and fever
African Tick Typhus (Rickettsiae)
Which illness spread by ticks causes fever followed by a rash on palms and soles 6 days later
Rocky Mountain spotted fever
What are the symptoms of dengue fever
Retro-orbital pains, back pains, myalgia (break bone fever), high grade pyrexia, rash, facial flushing
Which tick-bourne disease causes haemolytic anaemia, haemoglobinuria and polyclonal hypergammaglobulinaemia
Babesiosis
What is the post exposure prophylaxis for HCV
Monthly PCR tests
What is the management of botulism
ITU for intubation and antitoxin
What causes encephalopathy in measles and VZV
Post-infectious encephalopathy- brain swelling cause by immune response to infection
What is the presentation of histoplasmosis
South USA - Erythema nodosum, BHL, cavitating lesions on CXR
Which organism causes swimmers ear
Pseudomonas aeruginosa
Which organism causes cervical lymphadenopathy and an adherent greyish pharyngeal membrane
Diphtheria
What endotoxin is responsible for toxic shock syndrome in staph aureus infection
TSST-1 superantigen
Which exotoxins increase cAMP levels
Pertussis toxin, Cholera A toxin, Heat labile E. coli toxin
What is the MOA of amantadine
Inhibits uncoating of virus in the cell
Which organism is responsible for pharyngitis
Streptococcus pyogenes
What is the treatment of Listeria Meningitis
Amoxicillin + gentamicin (cephalosporins usually inadequate)
What are the symptoms of Legionella
Fever, dry cough, bradycardia, confusion, lymphopenia, hyponatraemia
What condition causes flu-like illness, then a brief remission, followed by jaundice and haematemesis
Yellow fever
What is the treatment of cerebral toxoplasmosis in HIV
Pyrimethamine + sulphadiazine for 6 weeks
Which opportunistic infection presents with exercise-induced desaturation and very few chest signs
PJP
Which class of antibiotics promotes MRSA along with beta-lactams
Quinolones
Which organism usually acquired from eggs in dog faeces causes visceral larva migrans
Toxocara canis (nematode)
What is the first step in chickenpox exposure in pregnancy
Check VZV Abs in the mother
What is the management of pubic lice
Permethrin or malathion cream applied to all body hair, reapplied after 3-7 days
How is Lassa fever spread
From infected rats or person-to-person
What are the 3 criteria for VZV Ig
- Significant exposure
- Clinical condition that increases risk (pregnancy, long term steroids, neonates)
- No antibodies to VZV
What prophylaxis is given to close contacts of a patient with pneumococcal meningitis
None - carriage is extremely common
What is the treatment of severe campylobacter
Clarithromycin
Which organisms are the most common cause of viral meningitis
Enteroviruses (coxakie, echovirus)
What is the best investigation for PJP
Bronchoalveolar lavage
What is the treatment of mycobacterium avium infection in HIV patients
Rifabutin + ethambutol + clarithromycin
What is the immediate management of meningitis in a patient with allergy to penicillins/cephalosporins
Chloramphenicol
What are the symptoms of chikungunya
Severe joint pain, high fever - africa, Asia, Indian subcontinent
What is the treatment of invasive amoebiasis
7 days metronidazole followed by 10 days diloxanide furoate
Which vaccines are live-attenuated
BCG, MMR, influenza (intranasal), oral rotavirus, oral polio, yellow fever, typhoid
What is the next step in a patient with suspected Lyme disease but no erythema migrans
ELISA antibody testing and start doxycycline
What is the treatment of cryptosporidium in immunocompromised patients
Nitazoxanide
Which hepatitis carries significant mortality in pregnancy
Hepatitis E
Which organism causes filariasis (lymphatic obstruction)
Wuchereria Bancrofti
What is the treatment of non-specific urethritis
Doxycycline 1 week
Which bacteria is responsible for bacterial vaginosis
Gardnerella vaginalis
Which type of leprosy is associated with hair loss
Tuberculoid leprosy
Which bacterial chest infection is associated with cavitating lesions and is seen after influenza infection
Staph aureus
Which viral meningitis is associated with unusually low glucose
Mumps
What is the MOA of telbuvudine in the treatment of HBV
Synthetic thymidine nucleoside analogue
What is the clinical picture of botulinum toxin
Afebrile, descending flaccid paralysis, slurred speech, diplopia, ptosis
What is first line treatment of hydatid disease (dog tapeworm Echinococcus granulosus)
Albendazole
Which bacteria is found in unpasteurised dairy and causes sweating with a ‘wet hay’ smell
Brucella melitensis
Which antibiotics are bacteriostatic
Chloramphenicol, macrolides, tetracyclines, sulphonamides, trimethoprim
Which virus is associated with nasopharyngeal carcinoma
EBV
Which vaccines cannot be used in egg anaphylaxis
Yellow fever, MMR
Which condition describes an infectious thrombophlebitis of the internal jugular vein
Lemierre’s syndrome
What are the most common viral organisms that cause meningitis
Coxsackie, echovirus
What drugs act as CCR5 fusion inhibitors in HIV treatment
Maraviroc, enfuviritide
Which vaccines are absolutely contraindicated in HIV-infected adults
Cholera, intranasal influenza, poliomyelitis, tuberculosis
Which complication of malaria can cause haemoglobinuria, AKI and anaemia
Blackwater fever
What is first line investigation for chlamydia
Women: vulvovaginal swab Men: urine test
What is second line treatment for genital warts after topics podophyllum
Topical imiquimod
What does thick film look for in malaria
Parasite burden
What does thin film look for in malaria
Species of malaria
What is the management of VZV exposure in >20 weeks pregnancy and not immune
Either VZIG or antivirals after day 7-14 of exposure
Which antiretroviral is an enzyme inducer
Nevirapine
What are the symptoms of HIV seroconversion
Like EBV (sore throat, lymphadenopathy, malaise, diarrhoea) with rash, mouth ulcers
What are the features of leptospirosis
Early: fever, flu, conjunctival erythema Immune phase (Weil’s disease): AKI, hepatitis, aseptic meningitis
What is the investigation of choice for leptospirosis
Serology for leptospira Abs
What is the causative organism of Rocky Mountain spotted fever
Rickettsia rickettsii
What is toxoplasmosis caused by
Toxoplasma gondii - intracellular protozoan (parasite)
What should be checked before and during ethambutol treatment
Visual acuity (causes optic neuritis)
How should recurrent HSV outbreaks in pregnancy be managed
Suppressive treatment with aciclovir from 36 weeks gestation
Which infection is transmitted through rabbit/beaver bites and produces ulcerating regional lymphadenopathy
Tularaemia
Which organism causes ring enhancing lesions on CT head in patients with HIV
Toxoplasmosis
What is the treatment of pseudomonas ear infection
Gentamicin drops
What contributes to the rapid progression of necrotising fasciitis
M protein
Which organism causes melioidosis
Burkholderia pseudomallei
What is the difference between oral hairy leukoplakia and oral candidiasis
Leukoplakia cannot be scratched off/dislodged
What is the most important cause of mortality in diphtheria
Myocarditis
What is the treatment of choice for severe leptospirosis
IV penicillin
What is first line treatment of syphillis
Benzylpenicillin IM
What is the first line treatment of uncomplicated chlamydia
7 days doxycycline
What is the best treatment for chlamydia in pregnancy
Oral azithromycin
What is the standard treatment of genital herpes
Oral aciclovir
What is the treatment of toxoplasma gondii brain abscess
Sulphadiazine and pyrimethamine
Which organism causes a tick bite eschar
Rickettsia conorii
What is the treatment of cryptosporidium in immunocompromised patients
Supportive therapy + nitazoxanide
Which infection associated with cattle farming causes back pain, hepatosplenomegaly and low platelets
Brucellosis
What is the treatment of brucellosis
6 weeks doxycycline + streptomycin/rifampicin
What bacteria is spiral shaped on EM
Campylobacter
What does the nematode Loa loa (loiasis) cause
Filariasis
What is the most common side effect of lamivudine
Bone marrow suppression
What spreads dengue fever
Aedes mosquito
What presents 6-60 days after renal transplant with flu like symptoms and fever
CMV infection
What is the treatment of CMV infection in renal transplant
IV ganciclovir
What is the MOA of oseltamivir
Neuraminidase inhibitor
What is the incubation period of salmonella gastroenteritis
6-72 hours
Which organism causes African river blindness
Onchocerca volvulus (most common cause of infective blindness worldwide)
Which organism causes a murmur and hepatitis after exposure in a farm in France
Coxiella (Q fever endocarditis)
What is the antibiotic of choice for nocardia/actinomycete chest infection in immunocompromised
Sulphonamides - sulphadiazine
Which HIV ART is associated with fat redistribution and an insulin resistant phenotype
Zidovudine
What is the most common cause of PID
Chlamydia trachomatis
What is the causative organism of cysticercosis
T.solium (pork tapeworm)
What is the most specific investigation for diagnosing neurocysticerosis
Fundoscopic examination to directly visualise subretinal parasites
What remains positive throughout life and only indicates previous syphillis infection
TPHA
Which form of leprosy is systemic with symmetrical distribution and more severe
Lepromatous leprosy
What is the treatment of strongyloides nematode infection
Ivermectin (albendazole if concurrent AIDS)
What investigation should be performed in adults diagnosed with molluscum contagiosum
HIV antigen test
Which vaccines are safe in HIV patients with low CD4 count
Help A, Hep B, flu, pneumococcal
What is the treatment of symptomatic shigella
Oral azithromycin
What causes gas gangrene
Clostridium perfringens (treat with benzylpenicillin + clindamycin)
What is the treatment of Coxiella infection
Doxycycline
What is the investigation for hydatid liver disease
ELISA testing for echinococcus
What is the treatment for latent TB whilst taking HAART
Isoniazid mono therapy 6-9 months
What test confirms the diagnosis of leprosy
Skin biopsy
What is the treatment of chancroid
Single dose IM ceftriaxone
What classification of bacteria is pertussis
Gram-negative coccobacillus
What presents with a painless penile ulcer and significant inguinal lymph node enlargement
Lymphogranuloma venereum
Which NRTI is associated with myocarditis/cardiomyopathy
Zidovudine
What is used to diagnose cryptococcus meningitis
India ink test
What are the features of severe malaria
- Hb <50
- BM <2.2
- pH <7.30
- Lactate >5
Which paramyxovirus infection presents with parotid swelling and raised amylase level
Mumps
Which STI is most likely to cause an acute hepatitis
Hepatitis B
What is the most common hepatitis to be transmitted via homosexual anal intercourse
Hepatitis B
What is the most important risk factor for spread of Hep C
IVDU
What is the treatment of systemic primary VZV infection in an immunocompromised patient
IV aciclovir
Which infections have an incubation period of 1-2 weeks
Measles
Malaria
Typhoid
Dengue