Infectious Diseases Flashcards
Mechanisms of resistance
Antibiotic inactivation
- Beta lactamases
- Pneumococcus and macrolides
- Enzymatic modification of aminoglycosides
Alteration of antibiotic target
- Pneumococcus and penicillin
- Staph aureus and methicillin like antibiotics
Decreased uptake
- Reduced penetration
- Antibiotic effluc
MRSA mechanism of resistance
Penicillin-binding protein mutation coded by the mecA gene on a transposon
MRSA treatment
Vancomycin
Teicoplanin
Rifampicin
Fusidic acid
Ciprofloxacin
Clindamycin
VISA mechanism of resistance
Genes code for factors such as additional peptidoglycan synthesis and reduced need for peptidoglycan cross-linking
VISA management
Teicoplanin
Linezolid
Quinupristin-dalforpristin
Cotrimoxazole
VRE pathogens
E faecium
E faecalis
VRE mechanism of resistance
- penicillin-binding protein mutations
- beta-lactamase production
- aminoglycoside-modifying enzymes
- antibiotic drug efflux pumps
- alterations in cell wall components coded by transposons (Van A to F phenotypes)
Treatment of VRE
Teicoplanin
Linezolid
Daptomycin
Tigecycline
Van A: resistant to vancomycin and teicoplanin
Van B: resistant to vancomycin, teicoplanin may be effective but resistance likely to emerge with prolonged use (use linezolid, tigecycline, dalfopristin-quinapristin, daptomycin)
Van C: partly resistant to vancomycin
ESCAPPM organisms
Enterobacter species
Serratia species
Citrobacter freundi
Aeromonas
Proteus vulgaris (non-mirabilus) + Pseudomonas
Providencia
Morganella morganii
ESCAPPM resistance and mechanism
Resistance to cephalosporins (especially third generation) due to overexpression of induceable chromosomal AmpC/β-lactamase enzymes.
Treatment of ESCAPPM
Carbapenems
Fourth generation cephalosporins
Ciprofloxacin
Aminoglycosides
Mechanism of penicillin resistance in staph aureus
- Production of beta-lactamase, conferred by the gene blaZ - inactivates penicillin by hydrolyzing the beta-lactam ring
- Altered penicillin-binding protein, PBP2a, encoded by mecA
Classes of beta lactamase enzymes
A - penicillinases (TEM, SHV, CTX-M)
B - metalloenzymes (NDM, VIM, IMP)
C - cephalosporinases (AmpC)
D - oxacillinases (OSA)
ESBL mechanism of resistance
Arise by
- mutations in old beta lactamase genes (i.e. TEM, SHV)
- Plasmid mediated transfer
ESBL organisms
Klebsiella
E coli
Salmonella
Proteus
Enterobacter
Citrobacter
Serratia
Pseudomonas
Treatment of ESBL
Carbapenems
Colistin
Amikacin
Ciprofloxcin
Metallo betalactamases organisms
Pseudomonas
Acinetobacter
Metallo betalactamases mechanism of resistnace
New Delhi metallo-Clactamase 1 (NDM-1) - an enzyme that produces resistance to a broad-range of beta-lactam antibiotics
produces a carbapenemase
Treatment of metallo-beta-lactamases
Tigecycline
Colistin
Linezolid mechanism
Activity against gram positive (+ mycobacteria, nocardia spp.)
Inhibits protein synthesis
Side effects of linezolid
GI upset
Cytopenias
Neuropathy
MAO inhibition (avoid SSRIs, tramadol, pethidine)
Daptomycin mechanism
Cyclic lipopeptide
Binds to cell membrane and leads to inhibition of synthesis of DNA, RNA and protein
Bactericidal activity against most gram positive
Tigecycline mechanism
Protein synthesis inhibitor
Bacteriostatic
Tigecycline targets
MRSA, MSSA, VISA, VRE - low MICs required
Active against gram negatives (except pseudomonas)
Ceftaroline/ceftobirole mechanism and targets
Novel cephalosporins
Active against MRSA
Not good for VRE
Colistin mechanism
Binds lipopolysaccharides and phospholipids in outer cell membrane
Leads to disruption of outer cell membrane, leakage and cell death
Colistin targets
Pseudomonas
Acinetobacter
E Coli
Enterobacter spp
Klebsiella
Salmonella
Stenotrophomonas
Fosfomycin mechanism
Inhibits MurA enzyme and bacterial cell wall biogenesis
Bactericidal
Fosfomycin targets
Targets gram -ve and +ve resistant cystitis UTIs
Not pseudomonas or morganella
Cefiderocol mechanism
Siderophore cephalosporin that binds to iron
Actively transported into bacterial cells
Cefiderol targets
Multi-resistant gram negatives
ESBL
Pseudomonas
Acinetobacter
Stenotrophomonas
Burkholderia
Prophylaxis for C-section, H&N, thoracic, neck, ortho
1st line - cefazolin 2g
2nd - vancomycin 25mg/kg
Prophylaxis for colorectal surgery, biliary, hysterectomy, major ENT, infrarenal vascular surgery
1st line - cefazolin + metronidazole
2nd line - vanc + gent
Prophylaxis for amputation
1st line - benzylpenicillin
2nd - metronidazole
Prophylaxis for ERCP
1st line - gentamycin
2nd line - cefazolin
Indications for dental prophylaxis
Mechanical valve
Prior IE
Congenital heart disease
Rheumatic heart disease
Heart transplant
Standard therapy for TB
2 weeks of isoniazid, rifampicin, ethambutol, pyridazinamide
4 weeks of isoniazid and rifampicin
Greatest risk of reactivating TB
HIV
Growing resistance to which antimicrobial in TB
Isoniazid > Rifampicin
Features of paradoxical reactions in TB
Clinical or radiological deterioration of pre-existing lesions or appearance of new lesions whilst on therapy
Presents with fever, nodes, respiratory failure, neuro deterioration, sinus formation
Treatment of paradoxical reactions in TB
Corticosteroids
Aspiration of pus
Excision
Continue anti-TB therapy
Mechanism of action of quantiferon gold assay
Exposes whole blood to TB antigens
Sensitised lymphocytes release measurable cytokines in response
Unable to differentiate latent vs active TB
Features of nodular bronchiectasis
Presents in elderly women with chronic suppressed cough
Affects RML and lingular segment
Features of fibronodular bronchiectasis
Middle-aged, male smokers/drinks
Presents with productive cough positive with MAC
Antibiotic guidelines of CAP
Mild CAP - doxycycline or amoxicillin (or clarithromycin)
Moderate CAP - Benzylpenicillin + doxycycline
Severe CAP - ceftriaxone + azithromycin
Indications to treat aspiration pneumonia with metronidazole
Terrible gums, foul smelling sputum
Severe EtOH abuse
Lung abscess with fluid level
Empyema or complete white out
Mechanisms of oseltamivir
Neuraminidase inhibitor
Reduces duration of flu symptoms by 1-2 days
More effective for Flu A than Flu B
Causes of avian influenza
Bird exposure
Features of pertussis
Incubation period: 1-4 weeks
Catarrhal phase (1-2 weeks) - non specific URTI features
Paroxysmal phase (2-6 weeks) - intense paroxysmal coughing
Convalescent phase - progressive reduction in symptoms
K1 Klebsiella pneumoniae features
Novel strain associated with community acquired liver abscesses, bacteraemia and endophthalmitis
More common in diabetes
Susceptible to ceftriaxone (unless ESBL)
Indications for surgery in endocarditis
Absolute
- Severe AR or MR
- Cardiac failure (related to valve dysfunction)
- Fungal or highly resistant organisms
- Perivalvular abscess or fistula
- Prosthetic valve endocarditis
Relative
- Multiple or severe embolism
- Uncontrolled infection (e.g. MSSA, pseudomonas, Q fever)
- Size of vegetation
Necrotising fasciitis bacteria and treatment
Usually group A strep, may be polymicrobial in diabetes
Treatment with penicillin, clindamycin, pip/taz +/- gent +/- IVIG
Surgery
Mycobacterium ulcerans features
From Bairnsdale, Phillip Island, Point Lonsdale, Daintree
Treatment with rifampicin + clarithromycin (or moxifloxacin)
Neisseria gonorrhoeae triad
Tenosynovitis, dermatitis and polyarthralgias without purulent arthritis
Features of Bartonella
Cat scratch disease - B. henselae and B. quintana
Cutaneous lesion at bite site after 3-10 days
Resolves in 1-4 months, sometimes longer
May have ocular features, encephalopathy, radiculitis, myelitis, cerebellar ataxia, granulomatous hepatitis or splenitis, or bone lesions
Types of tick-borne rickettsial infections
R. australias - Australian tick typhus
R. honei - Flinders Island spotted fever
R. rickettsi - Rocky Mountain SF
R. africae - African tick bite fever
Treatment for Rickettsia
Doxycycline
Anthrax features
Bacillus anthracis - gram positive spore forming bacterium
Clinical syndromes
- Inhalation
- Cutaneous
- GI
Features of Inhalational anthrax
Flu-like symptoms for two days
Sudden deterioration - severe SOB and hypoxia
Haemorrhagic mediastinum
Can cause pleural effusion, meningitis, low BP
Plague features
Yersinia pestis (enterobacteriae)
Reservoir - rats, gerbils, prairie dogs, other rodents
Transmission via infected fleas
Types
- Bubonic
- Pneumonia (primary or secondary)
- Septicaemic
- Meningitis, pharyngitis
Treatment with streptomycin, doxycycline, ciprofloxacin
Features of tularaemia
Francisella tularensis
Incubation 2-10 days
Sudden onset fever, chills
Headache
Malaise
Treatment with streptomycin, tetracycline or chloramphenicol
Features of botulism
Toxins A, B and E
Binds to pre-synaptic nerves to prevent release of acetyl choline
Affects CN than symmetrically descends
No sympathetic or sensory involvement
Food history
EMG
Supportive treatment +/- antitoxin or penicillin
Infections to suspect with red eyes
Leptospirosis
Measles
Dengue
Kawasaki
Adenovirus
Stevens-Johnson
Causes of nodular lymphangitis
Sporotrichosis (Sporothrix schenckii)
Nocardia spp
Mycobacterium marinum
Leishmania braziliensis
Francisella tularensis
Features of Whipples disease
Tropheryma whipplei, an intracellular gram-positive bacteria
Abdominal pain, intestinal malabsorption
Enteropathic arthritis
Cardiac symptoms
Neurological symptoms i.e. myoclonus, ataxia, oculomotor impairment
Vancomycin targets
Most gram positive
Carbapenem targets
Most gram positive, gram negative, anaerobes
Fluoroquinolones targets
Older (cipro, norflox) - most aerobic gram negatives (including pseudomonas)
Newer (moxiflox) - most gram positive, gram negative (not pseudomonas), anaerobes, TB, atypicals
Ceftriaxone targets
Streps
Gram negatives
Weak for staph and anaerobes
Penicillin targets
Streps
Enterococcus faecalis
Syphilis/spriochaetes
Meningococcus
Aminoglycosides targets
Gram negatives
Some gram positives
Not anaerobes
Macrolide targets
Atypicals
G+C
G-C
Non-enteric G-B
Mycobacteria
H. pylori
Clindamycin targets
Gram positive
Anaerobes
Doxycyline targets
Gram positive and gram negatives
Atypicals
Spriochaetes (lyme)
Rickettsia
Malaria
Co-trimaxazole
Aerobic G-B
Staph including NORSA
Nocardia
Listeria
Meliodosis
Rifampicin drug interactions
Induction of CYP450
Warfarin
Voriconazole
Protease inhibitors
AEDs
Methadone
Tamoxifen
SSRIs
CyA
Tacrolimus
Corticosteroids
Quinolone drug interactions
Reduced absorption with Ca, Fe, Zn, antacids
QT prolonging drugs
Voriconazole
Macrolides
Moxifloxacin
Pentamidine
Mefloquine
Bedaquiline
Cells infected by HIV
CD4+ T lymphocytes
Monocytes and macrophages
Dendritic cells
Astrocytes
Thymic progenitor cells
CD34+ progenitor cells
HIV lifecytle
1) Attachment and fusion
2) Reverse transcription
3) Integration
4) Transcription
5) Translation
6) Budding and maturation
Natural history of untreated HIV disease
Primary infection - rise in HIV viral load with wide dissemination of virus seeding of lymphoid organs
Clinical latency - decrease in HIV viral load and blood CD4 T cells
Fall in CD4 T cells - opportunistic diseases, rise in HIV viral load and death
Classes of HIV ART
1) Reverse transcriptase inhibitors - nucleoside/nucleotide analogues
2) Integrase inhibitors
3) Reverse transcriptase inhibitors - non-nucleoside reverse transcriptase inhibitors
4) Protease inhibitors
5) Entry inhibitors
Examples of NRTIs
Nucleoside analogues
- Lamivudine
- Emtricitabine
- Abacavir
Nucleotide analogues
- Tenofovir (disoproxil fumarate or alefenamide)
Examples of INSTIs
Raltegravir
Dolutegravir
Bictegravir
Examples of entry inhbitors
Fusion inhibitors - enfuvirtide
CCR5 inhibitors - maraviroc
Attachment inhibitor - ibalizumab, fostemsavir
Examples of protease inhibitors
Darunavir
Atazanavir
Examples of NNRTIs
Nevirapine
Efavirenz
Etravirine
Rilpivirine
Recommendation for treatment naive HIV
Doltegravir (INSTIs) + Lamivudine (3TC)
Suggested if starting HIV viral load < 500,000
Definition of treatment success
Virological suppression
Confirmed HIV RNA below limit of assay detection
Low level viraemia
Definition of virologic failure
Incomplete virologic response - HIV RNA > 200 after 24 weeks ART
Viral rebound - repeated detection of HIV RNA > 200 after viral suppression
Management of treatment experienced HIV pt
Drug resistance testing should be obtained whilst pt taking failing regimen
Genotype testing
- usually need HIV VL > 1000 for test
Phenotype testing
- though very expensive
Complications of ART
Drug resistance
Toxicities
Drug interactions
Cost
Tenofovir drug toxicity
Renal toxicity
Decline bone mineral density
Abacavir drug toxicity
Allergic reaction –> GIT symptoms, myalgia +/- rash, cough, leukopenia
Doubles risk of AMI
Tenofovir alefenamide vs donepexil
Less renal dysfunction and bone effects with TAF compared to TDF
Weight gain with TAF
Protease inhibitor toxicities
Dolutegravir, bictegravir
Insomnia, headache, dizziness, fatigue, nausea, diarrhoea
Weight gain
Efavirenz toxicities
NNRTIs
CNS side effects - vivid dreams, sleep change, headache
Rash
Teratogenic
PI and NNRTI metabolism
By hepatic cytochrome P4503A4 enzymes
Opportunistic infection and malignancy with HIV infected patients
CD4 cell count 200-500: Herpes zoster, pneumococcal pneumonia, oral candidiasis, tuberculosis
50-200: PJP, CNS toxoplasmosis, cryptococcus, Kaposi’s sarcoma, NHL, PCNS, lymhpoma
<50: Disseminated MAC, CMV retinitis, cryptosporidiosis
Features of IRIS
Inflammatory syndrome that can occur after initiation of ART and consists of either the appearance of a new condition or worsening of a preexisting condition (infection, malignancy or autoimmune)
Develops within 4–8 weeks of initiation of ART
Presentation varies depending on the underlying illness, however, patients often have clinical deterioration and localized tissue inflammation.
Risk factors for IRIS
CD4+ cells < 50
Older age
Genetic suscepitbility
Most commonly seen with mycobacteria Tb, cryptococcus meningitis, PJP and PML
Kaposi sarcoma virus association
HHV-8 disease
Disseminated mycobacterium avium complex (MAC) epidemiology
M avium causative agent in majority of AIDS patients with disseminated MAC
Transmission via inhalation, ingestion, inoculation, person-person transmission unlikely
Clinical manifestations of MAC
Fever
Night sweats
Abdominal pain
Diarrhoea
Wt loss
Cough
Lymphadenopathy
Lymphadenitis, pnumonitis, pericarditis, OM, skin or soft tissue abscesses, genital ulcers, CNS infections
Diagnosis of toxoplasma gondii encephalitis
Serum IgG
Imaging - oedematous enhancing lesions
PET scan can help distinguish TE from lymphoma
Brain biopsy - however presumptive diagnosis if clinical picture and above investigations positive
Treatment of toxoplasma gondii
Pyrimethamine 200mg first > 50mg-75mg daily + sulfadiazine + leucovorin
Corticosteroids if indicated for mass effect treatment
Anticonvulsants for seizures
Malaria life cycle
Infected anopheline mosquito injects sporozoites
Sporozoite passes to liver and multiplies
Infected cells burst and release merozoites into circulation to invade RBC
Asexual division into schizonts
Daughter merozoites released when RBC bursts
Invade other RBC
Features of P. falciparum on blood film
Multiple infected RBC but no enlargement of RBC
Crescent shaped gametocytes
Features of P. vivax on blood film
Fewer infected RBC
Swollen RBCs
Fine eosinophilic dots
Malaria bacteria with hypnozoites
P. vivax and P. ovale
Treat with primaquine
Diagnosis of malaria
Rapid diagnostic testing
Thick and thin films
- determines species and parasite count
- repeat if clinical suspicion high
Causes of false positive and false negative of T&T films
False negative - partial treatment, fluoroquinolones, tetracycles
False positive - artefacts, debris (Howell-Jolly, platelets)
Drug resistant genes in malarial treatments
Mefloquin and lumefantrine
- Pfmdr1
Chloroquine
- Pfmdr1, plasmodium falciparum chloroquine resistant transporter, K76T
Antifolate drugs (sulfadoxine-pyrimethamine)
- Point mutations in dihydrofolate reductase (DHFR) and hydropteroate synthase (DHTS) genes
Treatment of malaria
P. vivax, malariae, ovale and uncomplicated P. falciparum
- artemether + lumefantrine
- atovaquone + proguanil
- quinine sulfate + doxycycline
- primaquine for vivax and ovale
Severe malaria (chloroquine-resistant P. falciparum)
- IV artesunate or quinine
Features of severe malaria
Reduced consciousness
Jaundice
Oliguria
Severe anaemia
Hypoglycaemia
Pulmonary oedema
Features of typhoid fever
Faecal-oral spread
Fever, abdominal pain, constipation
LFT derangement
“Rose spots” - maculopapular, truncal distribution
Complications in 3rd-4th week
Leukopenia
Blood culture, stool culture
Complications of typhoid fever
Occur in 3rd-4th weeks
Intestinal perforation
Bone and joint
Endocarditis
Pericarditis
Splenic or liver abscess
Endovascular - grafts, atherosclerotic plaques, aneurysms
Treatment of typhoid fever
Azithromycin
Ciprofloxxacin
Ceftriaxone
Features of dengue
Fever
Headache and retro-orbital pain
MSK pain
Rash
“Break bone fever”
Typhoid fever bacteria
S. typhi, parathyroid
Dengue vector
Aedes aegyptii
Breeds around human dwellings
Diagnostic features of typhoid fever
Leukopenia
Neutropenia
Thrombocytopenia
LFT derangement
Arbovirus IgM serology
Amoebiasis bacteria
Entamoeba histolyica
Cycle of amoebiasis
Ingestion > excystation (small intestine) > trophozoite infection (colon)
Cysts remain viable for weeks-months in moist environments outside body
Diagnosis of amoebiasis
3 fresh stool specimen
Serology - antibodies detectable in 99% of pts with liver abscess
Management of amoebiasis
Metronidazole
Paromomycin or diloxanide furoate
Hepatitis A features
Acute, self limiting virus
Faecal-oral transmission - contaminated water, milk, food (seafood), institutionalised, travel to endemic areas
Highly contagious
Hepatitis A diagnosis
IgM anti-HAV
Pathogens in Traveller’s diarrhoea
E. coli (ETEC, EIEC)
Shigella sp
Salmonella sp
Campylobacter jejuni
Vibrio parahaemolyticus
Aeromonas hydrophila
Giardia lamblia
Entamoeba histolytica
Cryptosporidium sp,
Rotavirus, norwalk virus
Ebola virus
Filovirus family
Zaire ebolavirus
IP 11 days
- Fever
- Weakness
- Diarrhoea
Zika virus features
Flavivirus
Mosquito borne transmission (Aedes aegypti), mother-infant, sexual
- Acute febrile illness (rash, fever, arthralgia, conjunctivitis, myalgia, headache)
- Neurological
- Adverse foetal outcomes (microcephaly)
Symptomatic management
Influenza features
Droplet spread and direct contact
- Fever
- Headache
- Tiredness
- Respiratory tract symptoms
- Myalgia
Causes of aseptic meningitis
Enteroviral: echovirus, coxsackie
Mumps
EBV
CMV
HIV
HSV
TB
Cryptococcus
Leptospirosis
Syphilis
Non infectious - sarcoid, vasculitis, CNS lymphoma
Use of steroids in meningitis
Should have dexamethasone 10mg IV, before or with first dose of antibiotics then 6/24 for 4 days
Treatment of pneumococcal meningitis
Benzylpenicillin
If gram positive diplococci –> add on vancomycin
Infectious causes for diffuse erythematous rash
Scarlet fever
Toxic shock syndrome
Staph scalded skin syndrome
Dengue
Enteroviral infection
Infectious causes of purpuric rash
Meningococcaemia
Staphylococcal sepsis
Gonococcaemia
Rickettsial infection
Dengue
Enteroviral infection
Hepatitis B
Strep pyogenes bacteria
Beta haemolytic streptococcus
Features of impetigo
Erythematous papule > vesicle > pustule > yellow crust and purulent discharge
Spread to close contacts, schools
Associated scabies
Clinical syndromes of cellulitis
Beta haemolytic streptococci (group A, B, C, G)
Staph aureus
Pasteurella - dog/cat bite, with puncture wound
Aeromonas spp.
Vibrio spp.
Clostridia spp. - gram negative, immunocompromised
Mycobacteria marinum
Erisepelothrix
Features of necrotising myofasciitis
Acutely swollen and painful lower limb or abdominal wall
Severe pain
High fevers
Risk factors for necrotising myofasciitis
Diabetes
IVDU
Alcoholism
Local trauma
Surgery
Bowel pathology
Management of necrotising myofasciitis
Surgery
Broad spectrum antibiotics (meropenem, penicillin, clindamycin)
IVIg - improved mortality in group A strep
Causes of asplenia
Splenectomy
Functional asplenia/hyposplenism
- haematological - hereditary spherocytosis, sickle cell anaemia, thalassaemia major, Hodgkin’s disease, NHL, CLL, Sezary’s syndrome
- Splenic irradiation
- High dose steroid therapy
- Coeliac disease
- Bone marrow transplant
Risk of infections in splenectomy
Strep pneumoniae
Neisseria meningitidis
Haemophilus influenzae
Capnocytophaga canimorsus
Malaria
Infection risk with solid organ transplantation
Cardiac transplant
- pneumonia, mediastinitis
- CMV
- toxoplasmosis
- Nocardia
Liver
- Candida
- Hepatobiliary sepsis
- CMV hepatitis
Renal
- UTI
- CMV
- PJP
- Fungal e.g. cryptococcus
- BK nephropathy
Features of pneumocytis jiroveci
Ubiquitous fungus, reactivated in impaired cellular immunity
Diffuse bilateral interstitial infiltrates
Respiratory tract sampling
IF, PCR
Management with Bactrim, pentamidine, clindamycin or primaquine
Corticosteroids
Nocardia features
Gram positive
N. asteroides, N. farcinica, N. brasileinsis
Environmental, soil, organic matter, water
Clinical features
- Cutaneous/lymphocutaneous
- Pulmonary
- systemic/CNS
Management
- surgical drainage/debridement
- Bactrim –> for pulmonary disease (resistant for N. farcinica, N. otitidiscaviarum)
- imipenem, ceftriaxone
Toxoplasmosis features
T. gondii, parasite
Increased risk with T cell mediated defects
CNS, myocardial, pulmonary, chorioretinitis
Management with pyrimethamine/folinic acid, sulfadiazine or clindamycin
Toxoplasmosis lifecycle
Cats shed oocyst > sporulation occurs outside cat 1-5 days later (required to be infectious) > tachyzoite (human intestine) > cyst (tissue)
Features of candidiasis
C. albicans - commensal on skin, GIT, female genital tract
Active in ICU or immunosuppressed patients
Syndromes of candidiasis
Syndromes
- Disseminated candidiasis –> fever after neutrophil recovery, abdominal pain, increase ALP
- Candidaemia –> fever +/- sepsis, use with broad spectrum abx, CVC, urinary catheters, TPN, renal imapriment, GIT surgery, mucositis, neutropenia
Management of candidiasis
Immunocompetent
- Systemic antifungal treatment for 14 days
- Removal of device, drain any collection
Immunocompromised
- Systemic antifungal therapy, 10-14 days
Triazole
Echinocandins
Amphotericin
Features of aspergillus
Ubiquitous, environmental spores
A. flavus, A. fumigatus
Primary infection in lung, later dissemination
Syndromes
- Pulmonary aspergillosis
- Cerebral –> severe immunocompromised, sinusitis with bone erosion
- ABPA
- Aspergilloma
Management of aspergillus
Antifungal therapy - voriconazole, posaconazole, amphotericin B, caspofungin
Surgery if isolated lesions
Features of zygomycosis
Absidia spp., Mucor, rhizopus
Risk with acute leukaemia, solid organ transplantation, DKA, iron overload, burns
Involvement of paranasal sinuses with dissemination. tobrain and orbit
Features of cryptococcus
Budding yeast
C. neoformans var gattii (immunocompetent hosts), vars neoformans (immunodeficient hosts)
Elevated CSF opening pressure, protein and lymphocytes. Decreased glucose.
Management with amphotericin B and flucytosine
Multidrug resistant candida
Candida auris
Echinocandin therapy as first line
Schistosomiasis features
Penetration of intact skin by cercarial lavae in fresh water
Pruritic rash within days, febrile illness, fibrotic response in urinary tract or gut, chronic infection (colitis, portal HTN, urolithiasis, SCC bladder)
Diagnosis via serology, eosinophilia, urine/stool microscopy
Management of praziquantel
Features of ascariasis
A. lumbricoides
Most common human helminthic infection, usually asymptomatic
Adult worms in small intestine shed ova > ingested eggs hatch > migrate into intestinal wall and via portal veins to lungs + small intestine
Pulmonary (laval migration)
Nutritional
Mechanical i.e. SBO
Treatment with stool microscopy
Management with mebendazole, pyrantel pamoate
Rabies features
Infection by contact with respiratory secretions from animal hosts
Fever, headache, malaise in prodrome (4-10 days), encephalitic-hydrophobia, deliriu, agitation, arrhythmias, autonomic dysfunction, paralysis
Leptospirosis features
Spirochete zoonosis from contaminated water
Mild, self-limiting
Hyperbilirubiaemia, AKI, pulmonary haemorrhage
Biphasic illness
Supportive therapy with antibiotics (penicillin and doxycycline)
Melioidosis features
Burkholderia pseudomallei (gram negative rod, soil saprophyte)
SEA,Northern Australia
Diabetes, EtOH use are risk factors
Pneumonia, abscesses (spleen, prostate), OM, septic arthritis, skin. andsoft tissue infection, high mortality in sepsis
Treatment with ceftazidime, carbapenem
Common manifestations fo strongyloidiasis
GI symptoms
Hepatomegaly, hepatic abscess, abnormal LFTs
Respiratory symptoms - dyspnoea, bronchospasm, haemoptysis, bronchopneumonia, interlobular septal fibrosis
Eosinophilia
Bacterial meningiits
Erythematous serpinginous lesions
Gram negative septivaemia or sepsis
MOF
