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FRACP Exam > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Actinomyces Israelii

A

bacteria: gram positive rods anaerobic, long branching hyphae

  • look like fungus

site: normal oral/sinus flora

clinical: chronic, granulomatous, suppurative disease

treatment: amoxicillin/penicillin, surgery to sinus/abscess

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2
Q

Adenovirus

A

virus: adenoviridae ds DNA

clinical: respiratory disease, ocular infections (follicular conjunctivitis, keratoconjunctivitis), LN, GIT, haemorrhagic cystitis

  • pharyngoconjunctivital fever syndrome
  • resolves 1-2 weeks
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3
Q

Aeromonas

A

organism: gram negative rod

source: freshwater

clinical: diarrhoea (blood/mucous) >10 days, wound infections, necrotizing fasciitis

treatment: fluoroquinolone, 3rd gen cephalosporin, TMP

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4
Q

Allergic bronchopulmonary aspergillosis

A

risk factors: 7-10% asthmatics, 7% CF

mechanism: patient colonised aspergillus, causes exaggerated IgG/IgE response, causes bronchospasm/proximal bronchiectasis

  • elevated Th2 CD4+ cells then IL4/5/13 then increased eosinophils/IgE

clinical: rust coloured sputum

diagnosis:

  • serum: elevated IgE/eosinophils, serology
  • CXR: hyperinflation, parenchymal infiltrates, ring sign
  • CT: bronchiectasis

treatment: steroids 6/52, bronchodilators, itraconzole

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5
Q

Aminoglycosides

A

drugs: gentamicin, tobramycin, amikacin, neomycin

mechanism: inhibit binding of tRNA at ribosome 30s subunit

cover

  • +: enterococcus, listeria, MSSA, strep viridans
  • -: Ecoli, pseudomonas
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6
Q

Antibiotic site of action

A
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7
Q

Antigenic SHIFT

A

pathogenesis: influenza H and N proteins experience major change that can result in a pandemic

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8
Q

Aspergillosis

A

organism: fungi aspergillus

risk factors: neutropaenia, glucocorticoids, immunosuppressed

highest risk: solid organ transplant, GVHD, CMV infection, CGD

clinical: fever, chest pain, SOB, cough, haemoptysis

  • tracheobronchitis, chronic nec/cavitating pulmonary aspergillosis, rhinosinusitis, disseminated infection

diagnosis:

  • CXR: single/multiple cavitating lesions, patchy consolidation
  • CT: nodules in chest with “halo sign”

treatment: voriconazole

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9
Q

Astrovirus/Adenovirus/Parvovirus

A

incubation: 10-14hours

source: faecal contamined food

clinical: nausea, vomiting, diarrhoea, malaise, headache, abdominal pain, fever

  • duration 2-9 days
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10
Q

Atypical mycobacterium infection

A

organism: MAC, M.abscessus, M.Kansaii

mechanism: colonise endobronchial tree of CT patients

clinical: fevers, lymphadenitis

  • cutaneous disease: swimming pool granuloma, buruli ulcer

diagnosis: hilar LN/new infiltrates/cystic lesions, AFB sputum

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11
Q

Bacillus anthracis

A

bacteria: gram positive rods, aerobic, spore forming with protein capsule

disease: cutaneous, inhalation, GI anthrax

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12
Q

Bacterial meningitis

causes

A

0-1 month: GBS, E.coli, Listeria, S pneumo

1-3months: S pneumo, N meningitidis, GBS, H influenza, Ecoli

3m-2years: S pneumo, N meningitidis, H influenza

2yr-18yrs: S pneumo, N meningitidis, H influenza

>50yrs: S pneumo, N meningitidis, Listeria

Immunocompromised: Pseudomonas, S aureus, Salmonella, Listeria

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13
Q

Bartonella Henselae

A

bacteria: pleomorphic gram negative rods

disease: bacillary angiomastosis, cat scratch disease (LN)

treatment: doxycycline/erythromycin

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14
Q

Bone/joint infection

A

RF children: poor vasc supply due to growth plates

organism:

  • s aureus (most common)
  • salmonella (sickle cell)
  • s pneumo/Hib (unimmunised)
  • kingella (common <2yrs)
  • GBS/Ecoli (neonates)
  • n.gonorrhoea (sexually active)

investigations:

  • plan film (no changes <1wk)
  • bone scan (+ve 2 days)
  • MRI
  • US

treatment: IV fluclox 5 days then oral

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15
Q

Bordetella Pertussis

A

bacteria: encapsulated gram -ve cocci-bacilli

pathogenesis: attaches to mucosa via pertussis toxin and filamentous haemagluttinin causing toxin mediated mucosal damage

clinical: inspirating whooping cough

treatment: azithromycin, clarithromycin, bactrim

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16
Q

Borrellia Burgdorferi

A

organism: bacterial species of spirochete

location: north america

transmission: tick

clinical: lyme disease

  • erythema chronicum migrans
  • myocarditis/cardiomyopathy
  • arthritis
  • aseptic meningitis
  • neuropathies/FN palsy
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17
Q

Brucella melitensis

A

organism: gram negative coccobacilli aerobic

location: Mediterannean, Asia, Sth America

transmission: humans accidental host

  • main host farm animals spread unpasteurised milk

clinical:

  • triad: fever, arthritis, hepatosplenomegally

treatment: doxycycline

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18
Q

Burkholderia cepacia

A

organism: gram negative rods filamentous

clinical: CF respiratory

treatment: ceftazidime, ciprofloxacin, bactrim, tazocin, meropenem

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19
Q

Calciviruses

  • norovirus and sapovirus
A

incubation: 12-48hrs

source: shellfish, faecal contamination of food

clinical: nausea, vomiting, abdo cramps, diarrhoea, fever

  • vomiting more in children
  • lasts 12-60hrs

diagnosis: PCR/EM on stool, stool negative WCC

treatment: supportive

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20
Q

Campylobacter jejuni

A

organism: thin gram negative rods

clinical: gastro, bacteraemia, meningitis, pneumonia, pancreatitis, cholecystitis

complications: reactive arthritis, guillian-barre

treatment: macrolides

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21
Q

Carbapenem

A

mechanism: inhibit cell wall synthesis

drugs: imipenem, meropenem

cover: excellent gram positive/negative

NOT MRSA/atypicals/burkoholderia

cost: $$$

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22
Q

Cephalosporins

A

class: beta lactam antibiotics (disrupt peptidoglycan cell wall)

  • less susceptible to beta-lactamases than penicillins

drugs:

first gen: cefazolin, cephalexin

  • staph, strep, Ecoli, klebsiella

second gen: cefaclor, cefuroxime

  • less staph, strep, Ecoli, klebsiella, moraxella, meningococcus, salmonella, shigella, gonococcus

third gen: ceftriaxone, ceftazidime, cefotaxime

  • strep, serratia, citrobacter, aeromonas

fourth gen: cefepime

  • staph, strep, pseudomonas

* Good CNS penetration

** None effective listeria/MRSA

*** Ceftazidime, cefepime against pseudomonas

use: wide range of infections

side effects: 10% cross reactivity penicillin

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23
Q

Cerebral abscess

A

organism: S aureus, Strep, Anaerobes, fungal, E.coli

risk factors: CHD, sinus infection, immunodeficiency, prosthesis eg shunt

clinical:

  • early: fever, lethargy, headache
  • later: raised ICP, vomiting, headache, seizures, coma

diagnosis:

  • CT/MRI: show RING enhancement
  • DO NOT DO LP
    treatment: drain, AB (cefotaxime/metronidazole) for 4-6 weeks
    prognosis: mortality 15-20%, sequalae 50%
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24
Q

Chlamydia Trachomatis

A

bacteria: obligate intracellular parasite (can’t make ATP)

disease: urethritis/vaginitis, PID, conjunctivitis, Reiter disease
treatment: doxycycline, azithromycin, erythromycin

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25
Q

Chlamydophila spp.

(chlamydia pneumonia/psittaci)

A

bacteria: obligate intracellular parasite

disease: atypical chlamydia pneumonia

treatment: doxycycline

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26
Q

Chloramphenicol

A

cover: good positive/negative

adverse: grey baby syndrome (hepatic met), aplastic anaemia, BM hypoplasia

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27
Q

Clostridia

A

bacteria: gram positive rod spore forming

botulinum: blocks ACh release causing flaccid paralysis\

  • treatment: toxin Ig

tetani: prevents release glycine/GABA (inhibits inhibitor) causing excessive muscle contraction

  • treatment: anti-tetanospasmim Ig

perfringens (only non-motile): alpha toxin myonecrosis

difficile: nosocomial diarrhoea due to antibiotics, exotoxin A (enterotoxin) + B (cytotoxin), pseudomembranous colitis

- treatment: metronidazole, vancomycin

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28
Q

CMV in immunocompromised

A

risks: transplant from CMV +ve donor to -ve recipitent, decreased T cell function

clinical:

  • renal transplant: graft loss
  • liver transplant: hepatitis/colitis
  • lung/BMT: pneumonitis
  • cardiac: early myocarditis/late atherosclerosis
  • HIV: retininits/colitis/encephalitis

treatment: 2 weeks ganciclovir, then 6 months PO valganciclovir

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29
Q

Congenital HSV

A

congenital (rare): skin vesicles, eye damage, microcephaly

postnatal 3 categories:

  • skin/eye/mouth (50%): 20% neuro sequalae, no mortality
  • CNS disease/encephalitis (30%): 2-3 wks, meningitis, normal neuro imaging then oedema/haem/lesions
  • disseminated (25%): 1st week, sepsis, multiorgan (liver, lungs, adrenals, CNS, skin), 85% mortality

management: IV aciclovir 2-3 weeks, oral supression 6/12 post

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30
Q

Coronavirus

A

virus: coronaviridae, ss RNA

clinical: 15% common colds

  • croup, asthma, LRTOs, enteritis, colitis, SARS
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31
Q

Corynebacterium diptheriae

A

bacteria: gram positive rods aerobic, metachromic granules

  • exotoxin encoding bacteriophage

disease: pseudomembranes in oropharynx, cervical LN, myocarditis

treatment: erythromycin, penicillin

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32
Q

CSF interpretation

A

CSF cultures:

  • gram stain negative 60% meningitis
  • PCR for N meningitidis, S pneumo, HSV, enterovirus

CSF cytology:

  • bacterial: increased neutrophils/protein, decreased glucose
  • viral: increased lymphocytes, normal glucose/protein
  • TB: elevated lymphocytes/protein, low glucose
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33
Q

E.coli

A

bacteria: gram negative rods anaerobic

antigens: K (capsule), O (outer polysaccharide), H (flagellum)

disease: UTI gram negative sepsis, neonatal pneumonia

ETEC: traveller’s diarrhoea, LT+ST

EHEC: 0157:H7 blood diarrhoea, HUS (fever, haem anaemia, thrombocytopaenia, acute renal failure)

- source: uncooked hamburger meat

treatment: bactrim, gentamicin

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34
Q

EBV

A

virus: herpesvirus (HHV 4), ds DNA

spread: 50% positive by 5 yrs

mechanism: establishes latency in all adults

clinical: young usually asymptomatic

  • acute: 1-2 wks, fever, tonsillar sx, lymphadenopathy, hepatospleenomegally (60%)

- resolution phase: 3-4 weeks, enlarged nodes, severe fatigue

associations: malignancy, lymphoproliferative disease, neurologic (5%), ITP 20%, neutropaenia (GBS, facial nerve palsy, meningitis, transverse myelitis, peripheral neuritis), cardiac, resp, neck abscess, morbilliform rash post pernicillin, splenic rupture

diagnosis: low platelets, abnormal LFTs, serology/PCR, monospot (high spec, low sens)

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35
Q

Encapsulated bacteria

A

SHiNE SKiS

  • S.pneumo, Hib, N.meningitidis, E.coli,
  • Salmonella, Klebsiella, GBS
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36
Q

Encephalitis

A

definition: inflammation of the brain with generalised dysfunction cerebral function +/- altered consciousness

causes:

  • direct: HSV
  • immune: EBV, mycoplasma

treatment: IVIg for enteroviruses, azithromycin for mycoplasma

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37
Q

Enterococci

A

bacteria: gram positive cocci in pairs anaerobes

  • eg faecalis (80% infections), faecium

disease: 15% neonatal infections, UTI, subacute endocarditis, bacteraemia, endocarditis

resistance: common resistance VRE

treatement: vancomycin, linezolid, daptomycin, teicoplanin

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38
Q

Enterovirus

A

virus: picornavirus, ss RNA, include poliovirus, coxsackie, echovirus

epidemiology: summer/autumn, infants

transmission: incubation 3-6 days, resp shedding 1-3 weeks, faecal shedding 7-11 weeks

clinical: fever, malaise, rash, headache, pharyngitis, vesicular lesions buccal surfaces, fever, blisters palms/soles, vomiting diarrhoea, myositis, arthritis, orchitis

- enterovirus: high rates CNS/cardiopulm involvement (encephalitis, pulm oedema/haem, shock)

- enterovirus/coxsackie: acute haemorrhagic conjunctivitis, myocarditis/pericarditis (30% all myocarditis, usually coxsackie B, mortality <4%)

- enterovirus/coxsackie/echovirus: meningitis (>90% viral), encephalitis (10-20%, enterovirus 71), GBS, transverse myelitis, ospoclonus-myoclonus, brainstem encephalitis, acute flaccid paralysis

- coxsackie: RTI, pleuritic chest pain

neonatal infection: most asymptomatic, CNS necrosis, arrythmias, CCF, MI, hepatic necrosis/failure, NEC, myositis, vomiting, diarrhoea

diagnosis: PCR (stool/NPA/CSF)

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39
Q

ESCPM organisms

induce beta lactamases

A

organisms: enterobacter, serratia, citrobacter, aeromonas, proteus, morganella morghani

treatment: carbapenem

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40
Q

Ethambutol

A

mechanism: inhibits RNA synthesis for cell wall formation

use: TB

side effects: optic neuritis, do not use in young that you can’t monitor vision, headache, dizziness, confusion, hyperuricaemia, peripheral neuropathy, hepatotoxicity, pancytopaenia

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41
Q

Giardia

A

transmission: faecal-oral

pathophysiology: ingestion cyst then trophozoites released and adhere to wall to revert to cysts and shed in faeces

clinical: diarrhoea, malaise, abdo pain, weight loss, lactose intolerance (40%)

diagnosis: stool microscopy

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42
Q

Glycopeptides

A

drugs: vancomycin, teicoplanin

mechanism: bacteriocidal

  • inhibit cell wall synthesis

cover: many gram positive, NO gram negative

adverse: red man syndrome infusion dependant

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43
Q

Group B Strep

(GBS, S. agalactiae)

A

bacteria: gram positive cocci anaerobic in chains/diplococci

transmission: 25% pregnant women

clinical: perinatal disease (pneumonia, meningitis, sepsis)

treatment: benzylpenicillin + gentamicin (+ cefotaxime for meningitis_

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44
Q

Haemophilus Influenza

A

bacteria: small gram negative cocci-bacillus encapsulated

  • 6 strains have capsules
  • HiB most virulent

transmission: respiratory droplets

disease: septic arthritis, epiglottitis, meningitis, OM, pneumonia

treatment: 3rd gen cephalosporin, gentamicin, prophylaxis rifampin

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45
Q

Helicobacter Pylori

A

bacteria: gram negative rod

disease: chronic gastritis, duodenal/gastric ulcers, MALT tumours, gastric adenocarcinoma

treatment: triple therapy (PPI, amoxicillin, clarithomycin)

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46
Q

Hepatitis A

A

virus: picornaviridae

incubation: 28 days

source: shellfish, uncooked food

clinical: flu like, jaundice, dark urine for 1-2 weeks

diagnosis: increased ALT/bili, anti HepA IgM positive

treatment: supportive

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47
Q

Hepatitis B

A

diagnosis:

  • HBsAg: hallmark of infection
  • HBcAg: Ag expressed in infected hepatocytes and not in serum
  • Anti-HBc: detected through course of infection
  • HBeAh: from precore protein and marker of replication

- acute: HBsAg + antiHBc IgM

- previous: antiHBs and antiHBc IgG

- immune: antiHBs only

- chronic: HBsAg >6months

prevention: vaccine prevents 85%, Ig prevents 95%

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48
Q

Herpes simplex virus

A

virus: herpesvirus ds DNA

subtypes: HSV1 oral, HSV2 genital

clinical:

  • primary infections can be severe
  • recurrent infections: virus lies latent and can reactivate, less severe and shorter duration
  • skin vesicles and shallow ulcers on erythematous base
  • gingivostomatitis (kids 6m-5yrs), herpes labialis, cutaneous (herpes whitlow), genital (90% unaware of infection, urethritis, dysuria, discharge), ocular (unilater conjunctivitis with preauricular LN), CNS (HSV1 leading cause encephalitis)

diagnosis: PCR

treatment:

  • oral aciclovir <72hrs
  • genital acyclovir/famcilovir, valacyclovir
  • CNS or immunocompromised: IV acyclovir
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49
Q

Herpes zoster

Shingles

A

definition: unilateral vesicular eruption in well defined dermatomal distribution and acute neuritis

location: thoracic/lumbar most common

  • zoster keratitis/opthalmicus can result from opthalmic branch trigeminal nerve

treatment: immunocompetent: oral aciclovir 5x per day if <72hr post sx

  • immunocompromised: IV aciclovir
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50
Q

HHV6

Roseola/Sixth disease

A

virus: human herpes virus 6 and 7, ds DNA

incubation: 9 days

clinical:

  • 80% seropositive by 1 yr, peak 9-21 months
  • fever starts suddenly and lasts for 4 days
  • diffuse macular rash across torso starts with fever resolution
  • assoc cervical LN, febrile convulsion (15%), diarrhoea (70%)
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51
Q

HIV

epidemiology/pathophysiology

A

epidemiology: 4 million children worldwide

  • 90% in Africa, 15% access to ARR

pathophysiology:

  • retroviridae ss RNA Virus
  • HIV-1 and HIV-2 with different genetics

HIV-1 life cycle:

  • attaches to cell surface molecules of CD4 cell/macrophage via CXCR-4 fusion + CCR5
  • enters cell and viral RNA released into cytoplasm
  • viral RNA to DNA via reverse transcriptase, then to dsDNA with transcription/translation
  • viral RNA/proteins gather cell surface and protease cleaves viral protein so virus buds off and released into circulation
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52
Q

HIV treatment

A

3 medications HAART (avoid resistance)

  • 2 NRTI + NNRTI or PI

side effects: headache, diarrhoea, lipodystrophy, hepatitis, severe rashes, lactic acidosis, abacavir hypersensitivity syndrome

  • lipodystrophy syndrome: central distribution of fat, loss of peripheral fat, increased serum lipids, insulin resistance
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53
Q

HIV

children

A

clinical:

  • often not diagnosed (only 15% exposed tested)
  • faster disease progress
  • symptoms when CD4 200-300
  • CNS involvement more common

treatment:

  • HAART impacts on development
  • longer duration of treatment required

prognosis:

  • without ART 20-50% die <2yrs
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54
Q

HIV

clinical

A

2 prognostic indications:

  • HIV RNA viral load (strongest)
  • CD4 count (% in lymphocyte component of WCC)

clinical:

  • common + serious (>50%): sepsis, bacterial pneumonia
  • common +mild: OM, skin, soft tissue
  • less common: meningitis, UTI, abscess, bone/joint
  • opportunistic infections: PJP, atypical myobacterial (MAC), oral candidiasis, crytosporidium diarrhoea, HSV gingivostomatitis, VZV, CMV, RSV, JC virus

Systems:

  • CNS: JC virus progressive multifocal leukoencephalopathy, CMV, HSV, cryptococcus, coccidiodes inmitis
  • resp: S.pneumonia, H.influenze, M.catarrhalis, P.aeruginosa, lymphocytic interstitial pneumonitis (unknown cause, 25-40% kinds by 2-3yrs, treat steroids)
  • CV S: cardiomyopathy, LVH, arrhythmias, CCF
  • GIT: diarrhoea, abdo pain, FTT, malabsorption, oral thrush, oral hairy leukoplakia
  • skin: seborrhoeic dermatitis, eczema, HSV, molluscum, warts
  • haem: anaemia (70%), leukopaenia (30%), thrombocytopaenia (20%)
  • onc: NHL, primary CNS lymphoma, leiomyosarcoma, Kaposi sarcoma HHV8
55
Q

HIV

transmission and clinical

A

transmission:

  • vertical (infant HIV mo): 75% not infected, 15% infected labour, 5-10% pregnancy, 5-15% breastfeeding ie. 25-40% (can be reduced to <1% with HAART)
  • horizontal: transfusions (90% risk, 3% paed), needlestick (0.3% risk), unprotected anal sex (3%)/vaginal sex (0.3%), mucous membrane exp (0.09%)

stages of infection:

  • initially titre low but with replication reaches a threshold and viraemia occurs

1) seroconversion (2-6wks post exposure): flu like illness, fever, malaise, myalgia, pharyngitis, maculopapular rash

2) Asymptomatic infection OR persistent generalised lymphadenopathy (30%)

  • nodes >1cm diameter at 2 or more extra-inguinal sites for >3m
  • assoc humoral response to virus: CD8 limits infection by blocking chemoreceptors (CC5), hypergammaglobulinaemia induced, cytokine response
  • monocytes retain virus w/o dying act as reservoir, LN>blood

3) AIDS-related complex

  • constitutional collection symptoms/signs: fever, night sweats, diarrhoea, weight loss, minor infections

4) AIDs

  • CD4 count< 200x10^6
  • prognosis 2yrs if untreated
56
Q

HMV

A

virus: paramyxoviridae ss RNA

epidemiology: most<5yrs

clinical:

  • increased severity with RSV
  • fever, cough, rhinorrhoea, wheeze, OM, LRTI (bronchiolitis 60%, croup 18%, asthma 14%, pneumonia 8%)
  • causes 10% outpatient LRTI (2nd to RSV)

diagnosis: PCR

57
Q

Infective meningitis/encephalitis

A

bacterial: strep pneumoniae, Hib, neisseria meningitidis, mycobacterium tuberculosis, borrelia burgdorferi, mycoplasma pneumoniae, bartonella henselae, listeria monocytogenes

viral: HSV, West Nile virus, influenza, adenovirus, EBV, mumps, lymphocytic choriomeningitis virus, arboviruses

58
Q

Infective myocarditis/pericarditis

A

bacterial: staph aureus, Hib, mycoplasma pneumonia

viral: adenoviruses, influenza, parvovirus, cytomegalovirus

59
Q

Influenza

A

virus: orthomyxoviridae ss RNA, H1N1 (swine flu)

incubation: 1-7 days, highly contagious via droplets

clinical: fever 2-3d, chills, headache, myalgia, pneumonia, GIT

complications: bacterial infection, myositis, encephalopathy, Reye syndrome, cardiac

treatment: amantadine, zanamivir, oseltamavir

60
Q

Isoniazid

A

mechanism: interupts cell wall synthesis

use: TB

side effects: hepatotoxicity, peripheral neuropathy

61
Q

Klebsiella pneumonia

A

bacteria: gram negative rod with large polysaccharide capsule

  • 40% people carriers

disease: bacteraemia, CAP, UTI, meningitis, nosocomial infections

4 A’s: aspiration pneumonia, lung abscesses, alcoholics, diabetics

treatment: ceftriaxone

62
Q

Legionella pneumophilia

A

bacteria: gram negative rod waterborne, faculative intracellular

transmission: aerosole droplets, no human-human

disease: atypical pneumonia, Pontiac fever, flu-like symptoms

  • associated diarrhoea, vomiting, hyponatraemia, neuro (50%), hepatic dysfunction

diagnosis:

  • CXR: patchy lobar consolidation
  • sputum culture/serology/urinary Ag

treatment: erythromycin, fluoroquinolones

63
Q

Lemierre syndrome

A

definition: septic thrombophlebitis internal jugular vein

organism: anaerobic gram -ve rod fusobacterium necrophorum

clinical: pharyngitis/tonsillitis to thrombophlebitis to seeding of multiple organs with septic emboli

  • pneumonia may lead to resp failure in untreated cases

management:

  • blood culture
  • US jugular veins
  • CT chest
64
Q

Leptospira Interrogans

A

organism: spirochete

location: tropical regions

source: infects wild/domestic animals

transmission: reservoir animals shed organism in urine

clinical: fever, myaglias, headache, meningitis, pulmonitis, renal/liver failure

65
Q

Lincosamides

A

drug: clindamycin

mechanism: bacteriostatic

  • inhibit protein synthesis by binding 50s subunit

cover: staph/step

adverse: arrhythmias, pseudomembranous colitis

66
Q

Linezolid

A

cover: VRE, MRSA

adverse: $$$, hypertension

67
Q

Listeria Monocytogenes

A

organism: gram +ve bacilli anaerobic

source: environment, food

clinical:

  • in pregnancy crosses placenta and causes fetal infection
  • disease of neonate/immunocompromised: meningitis

treatment: benzyl penicillin + gentamicin

68
Q

Ludwig angina

A

definition: acute diffuse infection of submandibular/sublingual spaces

  • usually after cavity injuries or dental extraction

organism: bacterial mixed

clinical: induration floor of mouth/tongue

  • airway obstruction can occur
69
Q

Macrolides

A

drugs: erythromycin, roxithromycin, azithromycin, clarithromycin

mechanism:

  • bacteriostatic
  • inhibit translocation with ribosome 50s subunit

cover:

  • +: atypicals (chlamydia, legionella, mycoplasma)
  • -: moraxella, gonococcus, campylobacter

adverse: GI side effects

70
Q

Malaria

A

organism: anopheles mosquito

subtypes:

  • P.falciparum: most common
  • P.vivax: most lethal
  • P.ovale: most benign

incubation: 12-14 days

pathophysiology: invade RBCs, digest RBC protein/Hb, prevent RBC deformation and cause haemolysis

clinical: fever, sweats, headache, myalgia, nausea, vomiting, diarrhoea, abdominal pain, cough, anaemia, thrombocytopaenia, hepatosplenomegally, jaundice, LN

clinical children: convulsions, coma, hypoglycaemia, met acidosis, anaemia

71
Q

Mastoiditis

A

pathophysiology: infection extends to the air cells of the skull behind the ear inside the mastoid process

clinical: fevers, headache, pain, tenderness, swelling to mastoid region, discharge from ear

organisms: strep pneumo, GAS, staph aureus, strep pyogenes, moraxella catarrhalis, H.influenzae, Pseudo aeru

diagnosis: CT facial bones

treatment: IV AB +/- surgery

72
Q

Measles

A

virus: paramyxoviridae ss RNA

incubation: 7- 14 days

spread: 90% contacts, contagious 3-5 days prior to rash

clinical the 3 c’s: 1) cough 2) corzya 3) conjunctivitis

  • fever, rash starts behind ears, koplik spots
  • respiratory sx
  • cardiac (myocarditis, pericarditis, ECG changes)
  • neuro (abnormal EEG, encephalitis .1%, 25% sequalae)
  • subacute sclerosing panencephalitis: 7yrs post infection in 1/100,000, progressive fatal brain damage

diagnosis: serology, PCR, thrombocytopaenia, leukopaenia

contacts: MMR vaccine within 72 hours

  • normal human immunoglobulin (NHIG): infants <6m if mother is the contact or was <28 weeks, all infants 6-9 months, immunocompromise, nonimmune oregnant women, exposed and no vaccine <72hrs
  • if no contact tx given: exclude from school 14 days
73
Q

Meningococcal vaccine

A

meningococcal C conjugate vaccine

  • given 12 months
  • decreases invasive disease and carriage

No vaccine available for B subtype

74
Q

Monobactam

A

drug: aztreonam

adverse: no cross-reactivity other beta lactams

cover: NO gram positive, Ecoli, klebsiella, haemophilus, moraxella, shigella, yersinia

75
Q

Moraxella catarrhalis

A

organism: gram negative diplococcus

clinical: cold, sinusitis, OM

treatment: augmentin, cephalexin, bactrim, erythromycin

76
Q

Mumps

A

virus: paramyxoviridae ss RNA

transmission: incubation 12-25 days, spread droplets 1-2d pre and 7d post parotid swelling

clinical:

  • 2 days prodrome: headache, fever, vomiting
  • parotitis: bilateral 70%, peaks 3 days
  • meningitis+/- encephalitis 10-30%
  • orchitis: more common post puberty
  • other: pancreatitis, carditis, arthritis, thyroiditis

diagnosis: serology

prevention: MMR vaccine

77
Q

Mycobacterium avium intracellulare lymphadenitis

A

epidemiology: 1-5yrs

transmission: eating soil

location: submandibular LNs: preauricular/post cervical, axillary, inguinal LN

clinical: unilateral slowly enlarging LN

  • firm, painless, freely movable and not erythematous
  • suppurate after several weeks, central fluctuation, thinning overlying skin with red/purple discolouration
  • rupture with sinus formation

treatment: complete surgical excision + 6 months clarithromycin/rifabutin

78
Q

Mycobacterium leprae

A

bacteria: gram negative acid-fast rod, obligate intracellular pathogen

disease: tuberculoid (reactive skin test), lepromatous disease

  • associated ulnar nerve injury
79
Q

Mycobacterium tuberculosis

A

bacteria: gram negative acid fast rod aerobe

source: aerosolized droplets

disease: primary TB in upper lobes (Ghon focus: caseating necrosis/secondary calcification/fibrosis, Ghon complex: +LN), reactivation of latent infection (most common)

  • reactivation rate 10% lifetime

treatment: RIPE therapy: rifampin, isoniazid, pyrazinamide, ethanbutol

80
Q

Mycoplasma pneumoniae

A

organism: atypical gram +ve, no cell wall, self replicating

epidemiology: school ages, 40% 3-15yrs

incubation: 1-3 weeks

pathophysiology:

  • target cell wall of ciliated resp epithelium and induce cytokines

clinical: headache, malaise, low grade fever, cough, wheeze, rhinorrhoea, OM

extrapulmonary:

  • haem: haemolysis (cold agglutinin response in 60%) 2-3 wks post, thrombocytopaenia, coagulation defects
  • skin: mild to severe rash (SJS)
  • CNS: meningoencephalitis, peripheral neuropathy, transverse myelitis, CN palsy, cerebellar ataxia, GBS

diagnosis:

  • CXR: no specific, interstitial pneum lower lobes usually unilateral
  • bloods: low Hb, high WCC/platelets/ESR, myco serology IgM

treatment: macrolide

81
Q

Needlestick injury

A

risks: HepB 33%, HepC 3%, HIV 0.3%

prophylaxis:

  • HepB: non immunised/poor response given vaccine <12hrs, if known +ve source then HBIG and HepB vaccine
  • HepC: diagnostic tests with PCR immediately/4wk/12wk, Ab immediately/12wks, ALT/AST 4wks/12wks
  • HIV: +ve source then PEP if<72hrs, unknown is case-case
82
Q

Neisseria gonorrhoea

A

organism: gram negative diplococcus encapsulated aerobic

clinical: urethritis, vulvovaginitis, opthalmitis, disseminated disease (cardiac, osteomyelitis)

  • GUT infection: 2-5 days in men, 5-10 days in women
  • PID: dissemination from fallopian tubes to peritoneum and live
  • opthalmitis: uni or bilateral, hyperacute bacterial conjunctivitis within 12 hours of innoculation, severe and sight threatening

treatment: ceftriaxone

83
Q

Neisseria meningitidis

A

organism: gram negative diplococcus with polysaccharide capsule

  • serotypes B/C/Y cause 1/3 of cases each
  • B 75% and C 15% australia

epidemiology: 1/100,000 with 50%< 2 years

  • endemic with outbreaks
  • 2% infants and 30% adolescents carriers

clinical: bacteramiae, sepsis, meningococcaemia, meningococcal meningitis, arthritis, pharyngitis, pneumonia

  • induction of coagulation pathways causing vasculitis/DIC
  • acute meningococcaemia: pharyngitis, myalgia, weakness, vomiting, diarrhoea, headache rash 7%, limp pain, refusal to WB, septic shock, DIC, acidosis, coma
  • acute meningitis: headache, photophobia, lethargy, vomiting, nuchal rigidity, seizures, focal neuro signs

complications: skin infarctions, adrenal haemorrhage, myocarditis, deafness, erythema nodosum

treatment: ceftriaxone, prophylaxis with rifampicin or IM ceftriaxone

prognosis: 10% mortality highest age 15-24yrs

vaccine: quadrivalent vaccine (A, C, Y, W135)

84
Q

Nitroimidazoles

A

drugs: metronidazole, tindazole

mechanism: bacteriocidal

  • metabolise to active metabolites inhibit cell wall synthesis

cover: gram positive/negative anaeobes, anaerobic protozoa (giardia, entamoeba)

85
Q

Norcardia asteroides

A

organism: gram +ve bacilli aerobic

clinical: opportunistic infection

  • local or disseminated disease with suppurative infection

treatment: bactrim

86
Q

Orbital cellulitis

A

clinical: inflammation of tissues of the orbit, with proptosis, limited movement of eye, oedema of conjunctiva, inflammation and swelling or eyelids, decreased VA

pathophysiology: direct extention or venous spread

complications: optic nerve involvement, vision loss, cavernous sinus thrombosis, meningitis, subdural empyema, brain abscess

diagnosis: CT to detect subperiosteal abscess or intracranial extension

treatment: IV AB +/- drainage

87
Q

Osteomyelitis

A

incidence: 1/1000, 50% <5yrs, M>F 2:1

risk factors: sickle cell, immunodef, sepsis, trauma, indwelling device

site: tubular bones 80%, usually rapidly growing bones

  • 50% tibia/fibula/femur

chronic recurrent multifocal OM

  • non-bacterial, adolescents, periodic bone pain/fever, usually manidible/clavicle, XR with osteolytic lesions, treat with naproxim
88
Q

Parvovirus B19 induced reticulocytopaenia

A

population: patients with chronic haemolysis

  • eg. sickle cell, thalassaemia, pyruvate kinase deficiency

pathophysiology: develop transient and absolute reticulocytopaenia induced by virus

clinical: fever, malaise, lethargy, symptoms of profound anaemia

  • may have concurrent vasoocclusive pain crisis

diagnosis: low Hb, reticulocytopaenia

89
Q

Parvovirus B19

Fifth disease

A

virus: parvoviridiae DNA virus

transmission: 60% adults immune

incubation: 4-14 days, most infectious prior to rash

clinical:

  • non specific prodrome: fever, malaise, lethargy
  • 1 week: glove/sock rash, slapped cheek, circumoral pallor
  • 2 week: aplastic crisis: Hb 30-40

pregnancy: reduced RBC production causing hydrops fetalis

diagnosis: clinical, IgM

treatment: IVIg only if aplasia

rare associations: arthritis, neuro, myocarditis, cutaneous, haem, AI, hydrops fetalis in pregnancy

90
Q

Penicillins

A

drugs:

narrow spectrum (beta lactamase sensitive): penicillin

  • all strep, staph saprophyticus, enterococcus, meningococcus

penicillin with beta lactamase inhibitors: augmentin, timentin, tazocin

  • all gram positive, most gram negative NOT pseudomonas, meningococcus

anti-staph peniciilins: flucloxacillin, dicloxacillin, methacillin

  • staph, strep pyogenes only

moderate spectrum: amoxicillin, ampicillin

  • strep, staph saprophyticus, enterococcus, listeria, E.coli, haemophillus, meningococcus

broad spectrum: piperacillin, ticarcillin

  • strep, staph saprophyticus, enterococcus, listeria, most gram negative

use: gram positive infections (primarily strep), beta lactamase resistant can be used for staph. but not MRSA

mechanism: block bacterial peptidoglycan cell wall formation

  • beta lactam ring resembles D-ala D-ala portion of wall so inserts and prevents normal cell wall synthesis
  • beta lactamases open beta lactam ring

metabolism: liver

excretion: kidneys

side effects: rash, hypersensitivity

91
Q

PJP

Pneumocystis Jiroveci Pneumonia

A

organism: fungus pneumocystis jiroveci

incidence: peak 3-6m with neonatal HIV, mortality <1yr

clinical: fever, tachypnoea, SOB, hypoxemia

CXR: diffuse bilat interstitial infiltrate/diffuse alveolar disease

diagnosis: methylene blue fungal stain (fungal components turn black), immunofluorescent staining

treatment: bactrim

92
Q

Pneumococcal vaccine

A

components: 7 serotypes: 80% that cause disease

  • mutant diptheria toxin as carrier protein/aluminium phosph

administration: 2/4/6 months

protection: >95% protection against invasive disease by those strains

  • >85% protein all strains

clinical:

  • decreased OM, pneumo, carriage, AB use

adverse: local reaction 10%

** conjugated vaccine effective <2yrs

93
Q

Poliovirus

A

virus: picornaviridae ss RNA

aetiology: Asia, Africa

mechanism: affects anterior horn cells

clinical:

  • 95% asymptomatic
  • 5% abortive poliomyelitis (flulike)
  • 1% non paralytic polio (flu like, transient bladder/bowel dysfunction, nuchal rigidity)
  • 0.1% paralytic polio: spinal muscle (asym flaccid paralysis), bulbar (CN and medullary disease), polioencephalitis (seizures, coma, spastic paralysis), paralytic with resp insufficiency

diagnosis: virus in stool

management: supportive

94
Q

Polyomaviruses

A

viruses: BK and JC ds DNA viruses

transmission: oral/respiratory

risk factors: immunocompromised hosts

clinical:

BK virus:

  • renal transplants, renal tubulointerstitial nephritis, rarely ureteral stenosis
  • BMT: haemorrhagic/nonhaeorrhagic cystitis
  • also vasculopathy, meningoencephalopathy, retinitis, pneumonitis, hepatitis, SLE, GBS

diagnosis: BKV IgG, urine electron microscopy (cast like polyomavirus aggregates)

95
Q

Pseudomonas aeruginosa

A

bacteria: motile, gram negative rod aerobic

source: pool, hot tub

clinical: opportunistic pathogen, burn patients, CF, DM, shunts, catheters

  • erythema gangrenosum, septisaemia

treatment: ceftazidime/cefepime, tazocin, timentin, ticarcillin, carbenicillin, piperacillin

96
Q

Pyrazinamide

A

mechanism: bactericidal

use: TB

side effects: GI upset, hepatotoxicity (4%), hyperuricaemia

97
Q

Quinolones

A

drugs: ciprofloxacin, norfloxacin, moxifloxacin

mechanism: bacteriocidal

  • inhibit DNA gyrase, DNA not supercoiled, death

penetrance: IV=oral

cover: NO +, - rods/cocci/pseudomonas/mycobacteria

adverse: ciprofloxacin (skin sensitivity, tendinopathy, CNS stimulation)

98
Q

Quinsy

A

definition: bulging abscess caused by displacement of uvula

etiology: school aged/adolescents

clinical: trismus (spasm masseter muscles), “hot potato” voice, spasm of internal pterygoid that elevates the palate

99
Q

Retropharyngeal abscess

A

epidemiology: 1-6yos

mechanism: small LN disappear post 5 yrs

diagnosis: lateral neck XR with measurement of prevertebral space that exceeds x2 diameter of C2 suggest abscess or pockets in air

100
Q

Retropharyngeal abscess

A

epidemiology: <4yrs, M>F

clinical: fever, irritability, decreased intake, drooling, neck stiffness, torticollis, refusal to move neck, muffled voice, stridor, resp distress

organism: GAS, staph aureus, Hib, klebsiella, MAIC

diagnosis:

  • lateral neck XR: paravertebral space increased in depth compared to AP measurement of adjacent vertebrae, soft tissue mass, air/fluid level

treatment: IV AB +/- drainage

101
Q

Rheumatic fever

A

organism: streptococcus pyogenes

incidence: 3% untreated strep infections, age 5 to 14 years

risk factors: malnutrition/poverty

pathophysiology:

  • type II hypersensitivity reaction
  • strep Ab react to myocardium/joints

clinical:

  • symptoms 2-4 weeks post throat infection

2 major OR 1 major + 2 minor

- major manifestations (5): ‘JONES’

  • Joints (70%): early, migratory polyarthritis large joints
  • Obvious carditis (50%): MS, mumur MR/AR, pericarditis/pericardial effusion, cardiomegally/CCF
  • Nodules (<1%): hard painless nodules extensor surfaces, assoc carditis
  • Erythema marginatum (<3%): purple annular lesions LL/torso, disappear in cold
  • Sydenham chorea (15%): neuro/pysch, latent period to 8mths after other symptoms, initial emotional lability 1-4wks then chorea/motor weakness, increased antineuronal Ab
  • _minor manifestations ‘_crITERIA’: Inflammatory cells, Temp, Elevated ESR/CRP, Raised PR, Itself (hx), Arthralgia

diagnosis:

  • positive ASO, antiDNase B titres, elevated CRP/ESR, prolonged PR interval

treatment:

10 day treatment

  • IM ben pen every 3-4 weeks for a minimum of 10 years
102
Q

Rhinovirus

A

virus: ssRNA

clinical: most common cause ‘common cold’

  • less common fever, OM
103
Q

Rifampicin

A

drug: rifamycin antibiotic

mechanism: inhibits RNA polymerase

indication: TB

side effects: transient increase LFTs, GI upset, headache, dizziness, flulike, thrombocytopaenia, anaemia, orange tears/saliva/stools, induced CYP 450

104
Q

RSV

A

virus: paramyxoviridae ss RNA

incubation: 4-6 days, shed virus for 1-2 wks post infection

epidemiology: M>F, peak 2-5months, nearly ALL 2yo infected

clinical: rhinorrhoea, cough, desaturation, apnoea**, bronchiolitis (40-70%), viral pneumonia

management: supportive, 1% infected hospitalised

prevention: palivizumab RSV Ig (reduced risk recurrent wheeze in exprems), monthly IM during RSV season for <2yrs with CLD/home O2/CHD

diagnosis: NPA PCR

105
Q

Rubella

A

virus: rubella virus ssRNA

incubation: 14-21 days

clinical:

  • prodrome: fever, malaise, headache, conjunctivitis, eye pain
  • cervical LN
  • forchheimer sign: pinpoint petechiae on soft palate
  • rash to face spreads to rest of body

diagnosis: serology

106
Q

Salmonella

A

bacteria: gram negative motile rods aerobic

transmission: contaminated food/water eg. eggs, poultry, reptiles

clinical: gastroenteritis, meningitis (high mortality), bacteraemia (1-5% diarrhoea)

- typhoid fever: salmonella typhi (rose spots, pain, pea-soup diarrhoea)

treatment: antibiotics if <3 months or immunocompromised

  • ceftriaxone, ampicillin
107
Q

Salmonella typhi

A

incubation: 10-14 days

clinical

  • week 1: fever, headache, myalgia
  • week 2: vomiting, diarrhoea, cough
  • week 3: rose spots
  • resolves in 2-4 weeks
108
Q

Scarlet fever

A

definition: superantigen mediated toxic syndrome of GAS pharyngitis

mechanism: delayed-type skin reactivity to pyrogenic exotoxins A,B,C

  • formation of specific antitoxin antibodies

clinical:

  • rash within 24-48 hours of symptoms lasting 3-4 days
  • diffuse, papular erythematous sandpaper blancing rash to neck/trunk/extremities with desquamation
  • face spared and circumoral pallor
  • strawberry tongue

prognosis: mortality 20% untreated, 1% treated

109
Q

Schistosoma haematobium

(schistosomiasis)

A

parasite: trematode (flat worms)

location: Africa, Middle East

transmission: direct penetration of skin from eggs in freshwater

pathogenesis: related to immune system response to eggs that invade local tissue

  • can cause fibrosis/scarring

clinical:

- GI: abdominal pain, diarrhoea, PR bleeding, HSM

  • GU: bladder/gonadal fibrosis, renal dysfunction

diagnosis: eggs in urine/stool

treatment: praziquantel

110
Q

Shigella

A

bacteria: gram negative rod

pathophysiology: phagocytosed and replicated intracellularly and spreads cell-cell

  • releases shiga toxin
  • infection with <10 organisms

clinical: bloody diarrhoea, WCC in stool

treatment: amoxycillin, bactrim

111
Q

Staph epidermidis

A

bacteria: gram positive cocci in clusters

source: normal skin flora with low virulence

clinical: infection if foreign body or immune compromise only

  • prosthetic devices (heart valves, catheters)

treatment: vancomycin (usually resistant to vancomycin)

112
Q

Staph scalded skin syndrome

A

mechanism: epidermolytic/exfoliative toxins A or B

  • act on zona granulosa of epidermis
  • granular layer split by binding desmoglein I in desmosomes
  • formation of fragile/tense bullae

clinical: <5yrs

  • rash preceded by fever, malaise, conjunctivitis, tender/erythematous skin
  • 1-2 days later: flaccid blisters with Nikolsky’s sign
  • no scarring

diagnosis:

  • bullae: sterile
  • skin biopsy: cleave plane in lower stratum granulosum with minimal necrosis, NO inflammatory infiltrate

treatment: IV penicillin

113
Q

Staphylococcus aureus

A

bacteria: gram positive cocci in clusters

  • coagulase positive
  • forms yellow golden colonies

pathophysiology:

  • major virulence factor protein A: interacts IgG preventing opsonisation
  • techoic acid: adhesion to mucosal cells
  • slime layer: protects from opsonisation
  • coagulase: interacts with fibrinogen to cause organism clumping and protect from phagcytocsis
  • catalase: inactivates H2O2
  • beta lactamase: AB resistance

clinical: tissue abscesses, soft tissue infection, pneumonia (HAP), osteomyelitis, impetigo

exotoxin mediation: TST, SSS, food poisoning

- toxins: TSST-1, enterotoxin (both superantigens)

  • effects persist despite treatment

methicillin resistance: conferred by altered penicillin proteins

MSSA treatment: flucloxacillin

MRSA treatment: clindamycin + ciprofloxacin, vancomycin, linezolid

114
Q

Strenotrophomonas maltophilia infection

A

organism: gram negative bacillus

source: hospital environment, tap water, nebulisers

infection: opportunistic serious infection in ICU typically ventilators

115
Q

Streptococcus viridans

A

bacteria: commensal gram positive cocci

clinical: dental caries

116
Q

Streptococcus

A

organism: gram positive cocci catalase negative

Lancefield grouping (based on carbohydrate composition)

  • group A: strep pyogenes
  • group B: strep agalactiae
  • group C/D: beta haemolytic strep
  • group D: enterococcus
  • group E/F: alpha haemolytic (S. pneumoniae and viridans)
117
Q

Streptococcus pneumoniae

A

bacteria: gram positive cocci in pairs or chains

  • 90 serotypes, encapsulated most virilent
  • virulence factor: IgA protease, polysaccharide capsule

clinical: most common cause of bacteraemia (80%), bacterial pneumonia, and OM in childrens

  • also meningitis (2nd most common cause), sinusitis, osteomyelitis, brain abscess, empyema, pericarditis

treatment: benzyl penicillin + gentamicin

complications: increased severity with SS, B cell defects, HIV, leukaemia, aplasia

risk factors: <2yrs, male, SS/asplenia, HIV, cochlear implant, immunse disease, immunosuppresion

vaccination: PPV23 covers >95% invasive serotypes, decrease invasive infection 93%, decreased lobar pneumonia 73%

118
Q

Streptococcus pyogenes

(group A strep)

A

bacteria: gram positive cocci in chains

  • >100 serotypes

virulence: M protein resistance to phagocytosis

toxins: 3 pyrogenic exotoxins (SpeA,SpeB,SpeC)

  • SpeB: necrotising fasciitis

enzymes: hyaluronidase, streptokinase, steptolysin O/S

clinical: pharyngitis, impetigo, eryspialis/cellutitis

toxin mediated disease: scarlet fever, TSLS, necrotizing fasc

  • scarlet fever: pharyngitis, strawberry tongue, sandpaper like rash

risk factors: age 3-15yrs, winter, HIV, DM, chronic disease

AI disease: rheumatic fever, post strep GN

treatment: benzyl penicillin

119
Q

Sulphonamides

A

mechanism: inhibit production of folic acid needed for DNA synthesis

drugs: bactrim

cover

  • +: enterococcus, listeria, GAS, PCP NO staph/strep
  • -: Ecoli
120
Q

Tetracyclines

A

drugs: tetracycline, doxycycline, minocycline

mechanism:

  • bacteriostatis
  • inhibit binding of tRNA at 30s subunit ribosome

cover: + staph, strep, malaria, cholera, NO -

121
Q

Toxic shock syndrome

A

organism: staph and strep superantigens

  • staph aureus: toxic shock syndrome causing toxin (TSST)
  • strep pyogenes: strep pyrogenic exotoxins

mechanism:

  • superantigens create toxins A,B,C,D,E
  • superantigens join APC non specifically and cause massive Tcell proliferation and cytokine release

clinical: shock with liver, renal, pulmonary, neuro sx

diagnosis:

  • s.aureus: blood cultures negative
  • GAS: blood cultures positive
  • thromboytopaenia

treatment: treat shock/source of infection, antibiotics, IvIG, clindamycin (stops toxin transcription)

122
Q

Treatment meningitis contacts

A

Treat all close contacts ASAP

  • AB prophylaxis for household of contacts in last 7 days

Antibiotics

  • children rifampicin 2/7
  • adults: IM ceftriaxone or cipro or fluclox STAT

DO NOT GIVE rifampicin/ciprofloxacin in pregnancy: teratogenic

123
Q

Treatment of Pseudomonas

AAC CT

A

Aminoglycosides (gentamicin/tobramycin)

Aztreonam

Cephalosporin (ceftazidime/cefipime)

Carbapenem

Timentin

124
Q

Treponema pallidum

A

bacteria: spirochete

clinical:

  • primary syphillis: painless chancre
  • secondary: 1-6months condylomo lata
  • tertiary: 1-10yrs, gumma formation, neuro sx
  • congenital: rhinoritis, lesions, hepatospleenomegally, haemolytic anaemia/thrombo

diagnosis: VDRL, RPR, syphilus IgM

125
Q

Trimethoprim

A

mechanism: competetively inihibit bacterial folate production

126
Q

Tuberculosis

epidemiology, clinical

A

organism: gram +ve bacilli aerobes mycoplasma tuberculosis

epidemiology: rate of new cases/mortality falling

  • highest risk 0-1yrs
  • 10% cases worldwide are children
  • highest burden: Africa, Asia, Latin America
  • 10% coinfected HIV

transmission: droplets, untreated infected person 15 others/yr

etiology: 5 mycobacteria in M.tuberculosis complex: M.tuberculosis, M.bovis, M.africanum, M.microti, M.canetti

pathophysiology:

_1) initial infection: i_nhalation of droplet, 40% chance develop TB

  • local infection at portal of entry: bacilli carried to LN by macrophages
  • local tissue inflammation with LN/parenchyma causing tissue hypersensitivity
  • progression to fibrosis/calcification/caseation= caseating granuloma (primary Gohn complex)

2) Post primary infection

  • 90% enter latent phase/10% develop TB pneumonia

3) Clinical disease

  • disseminated/meningeal 2-6 months
  • pulmonary 3-9 months
  • bones/joints year

4) Reactivation

  • >1yr after initial infection
  • endogenous regrowth of partially encapsulated lesions

clinical:

  • asymptomatic early stages

pulm TB: chronic cough, fever>38 for >2wks, weight loss, FTT

  • primary TB CXR: regional lymphadenitis, small lung focus, pleural effusion
  • miliary TB CXR: diffuse millet seeds
  • reactivation TB: right upper lobe

_extrapulmonary (_25% presentation)

  • disseminated disease (hepatosplenomegally, LN, skin, CNS (0.3%), pericardial effusion, abdominal, renal, bones)

TB/HIV coinfection: increased mortality/dissemination/extrapulmonary

perinatal infection: mortality 50%, onset 2-3wks sepsis, congenital rare

MDR TB: need 18m treatment, difficult to treat

127
Q

Tuberculosis

diagnosis and treatment

A

diagnosis:

  • organism tests: microscopy, AFB, culture from body fluid (8-10wks), molecular testing (40-80% sensitive if smear positive, NAAT, PcR)
  • immune response tests: TST (crossreacts BCH, false negatives), immune response test, quantaferon gold (IFN-g release assay)
  • ALWAYS test for HIV

prevention: vaccine BCG: 50% effective preventing pulm TB, 50-80% effective preventing disseminated/meningeal TB, time limited

treatment: RIPEx2, RIx4

  • RIPE for 2 months then RI for 4 more months
  • if MDR then for 19 months
  • TB meningitis for 6-9months
128
Q

Varicella zoster

A

virus: herpesviridae ds DNA

incubation: 10-21 days

transmission: 80-90% households, 1-2d before rash and until crusts over

clinical: fever, pruritic rash, headache, malaise, anorexia

  • complications: pneumonia, postinfectious cerebellar ataxia (1/4000), encephalitis (1/100,000), zoster

post exposure: vaccine<72 hrs

  • ZIG: pregnant women <96hrs, neonates from day 5 prior and 2 days post birth if mother develops, neonates <30d old if mother negative, premature infants <28wks, immunosuppressed
  • immunocompromise: ZIG and IV aciclovir
  • “significant exposure”: face-face>5 mins, same household, same room>1hr
129
Q

Vibrio cholerae

A

bacteria: comma-shaped motile gram negative rod

  • large inoculum required

transmission: faecal oral

pathophysiology:

  • do NOT invade GI mucosa/blood
  • cholera toxin: AB exotoxin, increased cAMP and Cl secretion causing increased Bicarb secretion

clinical: large watery mucous gastroenteritis (rice water stool)

  • 20% severe dehydration

treatment: doxycycline, tetracycline

130
Q

Viral meningitis

A

viruses:

  • enterovirus (most common)
  • herpesvirus: HSV1 (most severe/encephalitis), HSV2 (neonates)
  • VZV (cerebellar ataxia to severe encephalitis)
  • CMV/HHV6: immunocompromised
    also: EBV, arbovirus, adenovirus, influenza,lymphocytic choriomeningitis virus, measles, mumps, HIV

treatment: aciclovir for HSV otherwise supportive

131
Q

Yersinia enterocolitica

A

bacteria: gram negative rod, anaerobic, motile at 22 degrees

pathophysiology: terminal ileum, colonizes peyer’s patch causing terminal ileitis

  • fever, RIF pain

transmission: animal faeces

treatment: self-limited, bactrim, ceftriaxone

132
Q

Antifungal treatment

A

invasive aspergillus: voriconazole

candida: fluconazole, caspofungin

cryptococcus: amphotericin B

**Amphotericin good broad spectrum but toxic

133
Q

Antifungal drugs

A

polyenes (ampho, nystatin): make holes in cell membrane

azoles/terbinafine: interefere with celll membrane synthesis

echinocandins (caspofungin): inhibit cell was synthesis

griseofluvin/5 FC: cell division, NA synthesis inhibitor

FRACP Exam (23 decks)

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