Microbiology Flashcards
Actinomyces Israelii
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
Adenovirus
virus: adenoviridae ds DNA
clinical: respiratory disease, ocular infections (follicular conjunctivitis, keratoconjunctivitis), LN, GIT, haemorrhagic cystitis
- pharyngoconjunctivital fever syndrome
- resolves 1-2 weeks
Aeromonas
organism: gram negative rod
source: freshwater
clinical: diarrhoea (blood/mucous) >10 days, wound infections, necrotizing fasciitis
treatment: fluoroquinolone, 3rd gen cephalosporin, TMP
Allergic bronchopulmonary aspergillosis
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
Aminoglycosides
drugs: gentamicin, tobramycin, amikacin, neomycin
mechanism: inhibit binding of tRNA at ribosome 30s subunit
cover
- +: enterococcus, listeria, MSSA, strep viridans
- -: Ecoli, pseudomonas
Antibiotic site of action
Antigenic SHIFT
pathogenesis: influenza H and N proteins experience major change that can result in a pandemic
Aspergillosis
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
Astrovirus/Adenovirus/Parvovirus
incubation: 10-14hours
source: faecal contamined food
clinical: nausea, vomiting, diarrhoea, malaise, headache, abdominal pain, fever
- duration 2-9 days
Atypical mycobacterium infection
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
Bacillus anthracis
bacteria: gram positive rods, aerobic, spore forming with protein capsule
disease: cutaneous, inhalation, GI anthrax
Bacterial meningitis
causes
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
Bartonella Henselae
bacteria: pleomorphic gram negative rods
disease: bacillary angiomastosis, cat scratch disease (LN)
treatment: doxycycline/erythromycin
Bone/joint infection
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
Bordetella Pertussis
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
Borrellia Burgdorferi
organism: bacterial species of spirochete
location: north america
transmission: tick
clinical: lyme disease
- erythema chronicum migrans
- myocarditis/cardiomyopathy
- arthritis
- aseptic meningitis
- neuropathies/FN palsy
Brucella melitensis
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
Burkholderia cepacia
organism: gram negative rods filamentous
clinical: CF respiratory
treatment: ceftazidime, ciprofloxacin, bactrim, tazocin, meropenem
Calciviruses
- norovirus and sapovirus
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
Campylobacter jejuni
organism: thin gram negative rods
clinical: gastro, bacteraemia, meningitis, pneumonia, pancreatitis, cholecystitis
complications: reactive arthritis, guillian-barre
treatment: macrolides
Carbapenem
mechanism: inhibit cell wall synthesis
drugs: imipenem, meropenem
cover: excellent gram positive/negative
NOT MRSA/atypicals/burkoholderia
cost: $$$
Cephalosporins
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
Cerebral abscess
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%
Chlamydia Trachomatis
bacteria: obligate intracellular parasite (can’t make ATP)
disease: urethritis/vaginitis, PID, conjunctivitis, Reiter disease
treatment: doxycycline, azithromycin, erythromycin
Chlamydophila spp.
(chlamydia pneumonia/psittaci)
bacteria: obligate intracellular parasite
disease: atypical chlamydia pneumonia
treatment: doxycycline
Chloramphenicol
cover: good positive/negative
adverse: grey baby syndrome (hepatic met), aplastic anaemia, BM hypoplasia
Clostridia
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
CMV in immunocompromised
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
Congenital HSV
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
Coronavirus
virus: coronaviridae, ss RNA
clinical: 15% common colds
- croup, asthma, LRTOs, enteritis, colitis, SARS
Corynebacterium diptheriae
bacteria: gram positive rods aerobic, metachromic granules
- exotoxin encoding bacteriophage
disease: pseudomembranes in oropharynx, cervical LN, myocarditis
treatment: erythromycin, penicillin
CSF interpretation
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
E.coli
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
EBV
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)
Encapsulated bacteria
SHiNE SKiS
- S.pneumo, Hib, N.meningitidis, E.coli,
- Salmonella, Klebsiella, GBS
Encephalitis
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
Enterococci
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
Enterovirus
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)
ESCPM organisms
induce beta lactamases
organisms: enterobacter, serratia, citrobacter, aeromonas, proteus, morganella morghani
treatment: carbapenem
Ethambutol
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
Giardia
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
Glycopeptides
drugs: vancomycin, teicoplanin
mechanism: bacteriocidal
- inhibit cell wall synthesis
cover: many gram positive, NO gram negative
adverse: red man syndrome infusion dependant
Group B Strep
(GBS, S. agalactiae)
bacteria: gram positive cocci anaerobic in chains/diplococci
transmission: 25% pregnant women
clinical: perinatal disease (pneumonia, meningitis, sepsis)
treatment: benzylpenicillin + gentamicin (+ cefotaxime for meningitis_
Haemophilus Influenza
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
Helicobacter Pylori
bacteria: gram negative rod
disease: chronic gastritis, duodenal/gastric ulcers, MALT tumours, gastric adenocarcinoma
treatment: triple therapy (PPI, amoxicillin, clarithomycin)
Hepatitis 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
Hepatitis B
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%
Herpes simplex virus
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
Herpes zoster
Shingles
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
HHV6
Roseola/Sixth disease
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%)
HIV
epidemiology/pathophysiology
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
HIV treatment
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
HIV
children
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
HIV
clinical
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
HIV
transmission and clinical
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
HMV
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
Infective meningitis/encephalitis
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
Infective myocarditis/pericarditis
bacterial: staph aureus, Hib, mycoplasma pneumonia
viral: adenoviruses, influenza, parvovirus, cytomegalovirus
Influenza
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
Isoniazid
mechanism: interupts cell wall synthesis
use: TB
side effects: hepatotoxicity, peripheral neuropathy
Klebsiella pneumonia
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
Legionella pneumophilia
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
Lemierre syndrome
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
Leptospira Interrogans
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
Lincosamides
drug: clindamycin
mechanism: bacteriostatic
- inhibit protein synthesis by binding 50s subunit
cover: staph/step
adverse: arrhythmias, pseudomembranous colitis
Linezolid
cover: VRE, MRSA
adverse: $$$, hypertension
Listeria Monocytogenes
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
Ludwig angina
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
Macrolides
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
Malaria
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
Mastoiditis
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
Measles
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
Meningococcal vaccine
meningococcal C conjugate vaccine
- given 12 months
- decreases invasive disease and carriage
No vaccine available for B subtype
Monobactam
drug: aztreonam
adverse: no cross-reactivity other beta lactams
cover: NO gram positive, Ecoli, klebsiella, haemophilus, moraxella, shigella, yersinia
Moraxella catarrhalis
organism: gram negative diplococcus
clinical: cold, sinusitis, OM
treatment: augmentin, cephalexin, bactrim, erythromycin
Mumps
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
Mycobacterium avium intracellulare lymphadenitis
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
Mycobacterium leprae
bacteria: gram negative acid-fast rod, obligate intracellular pathogen
disease: tuberculoid (reactive skin test), lepromatous disease
- associated ulnar nerve injury
Mycobacterium tuberculosis
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
Mycoplasma pneumoniae
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
Needlestick injury
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
Neisseria gonorrhoea
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
Neisseria meningitidis
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)
Nitroimidazoles
drugs: metronidazole, tindazole
mechanism: bacteriocidal
- metabolise to active metabolites inhibit cell wall synthesis
cover: gram positive/negative anaeobes, anaerobic protozoa (giardia, entamoeba)
Norcardia asteroides
organism: gram +ve bacilli aerobic
clinical: opportunistic infection
- local or disseminated disease with suppurative infection
treatment: bactrim
Orbital cellulitis
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
Osteomyelitis
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
Parvovirus B19 induced reticulocytopaenia
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
Parvovirus B19
Fifth disease
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
Penicillins
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
PJP
Pneumocystis Jiroveci Pneumonia
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
Pneumococcal vaccine
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
Poliovirus
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
Polyomaviruses
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)
Pseudomonas aeruginosa
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
Pyrazinamide
mechanism: bactericidal
use: TB
side effects: GI upset, hepatotoxicity (4%), hyperuricaemia
Quinolones
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)
Quinsy
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
Retropharyngeal abscess
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
Retropharyngeal abscess
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
Rheumatic fever
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
Rhinovirus
virus: ssRNA
clinical: most common cause ‘common cold’
- less common fever, OM
Rifampicin
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
RSV
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
Rubella
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
Salmonella
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
Salmonella typhi
incubation: 10-14 days
clinical
- week 1: fever, headache, myalgia
- week 2: vomiting, diarrhoea, cough
- week 3: rose spots
- resolves in 2-4 weeks
Scarlet fever
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
Schistosoma haematobium
(schistosomiasis)
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
Shigella
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
Staph epidermidis
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)
Staph scalded skin syndrome
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
Staphylococcus aureus
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
Strenotrophomonas maltophilia infection
organism: gram negative bacillus
source: hospital environment, tap water, nebulisers
infection: opportunistic serious infection in ICU typically ventilators
Streptococcus viridans
bacteria: commensal gram positive cocci
clinical: dental caries
Streptococcus
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)
Streptococcus pneumoniae
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%
Streptococcus pyogenes
(group A strep)
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
Sulphonamides
mechanism: inhibit production of folic acid needed for DNA synthesis
drugs: bactrim
cover
- +: enterococcus, listeria, GAS, PCP NO staph/strep
- -: Ecoli
Tetracyclines
drugs: tetracycline, doxycycline, minocycline
mechanism:
- bacteriostatis
- inhibit binding of tRNA at 30s subunit ribosome
cover: + staph, strep, malaria, cholera, NO -
Toxic shock syndrome
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)
Treatment meningitis contacts
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
Treatment of Pseudomonas
AAC CT
Aminoglycosides (gentamicin/tobramycin)
Aztreonam
Cephalosporin (ceftazidime/cefipime)
Carbapenem
Timentin
Treponema pallidum
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
Trimethoprim
mechanism: competetively inihibit bacterial folate production
Tuberculosis
epidemiology, clinical
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
Tuberculosis
diagnosis and treatment
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
Varicella zoster
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
Vibrio cholerae
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
Viral meningitis
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
Yersinia enterocolitica
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
Antifungal treatment
invasive aspergillus: voriconazole
candida: fluconazole, caspofungin
cryptococcus: amphotericin B
**Amphotericin good broad spectrum but toxic
Antifungal drugs
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
