micro Flashcards
hiv drug in pregnancy
Zidovudine
fungal antigens and which fungus ?
beta-d-glucan= candida
galactomannan= aspergillus
glucuronoxylomannan= cryptococcus
which abx for lyme disease and which organim?
spirochaete = Borrelia burgdorferi
abx = doxycycline
depending on CURB 65 what abx regimen ??
0-1 (mild) Amoxicillin PO 5d 2nd line or if pen allergic-macrolide PO Outpatient treatment
2 (mod) Amoxicillin PO + Clarithromycin PO Consider admission
3-5 (severe) Co-amoxiclav IV + Clarithromycin IV Admit +/- consider ITU
remember this is for community acquired pneumonia
Treatment of Hospital-Acquired Pneumonia:
- 1st line: ciprofloxacin + vancomycin
- If severe: tazocin + vancomycin
- Aspiration pneumonia: tazocin + metronidazole
how to calc curb 65 score ?
Calculate CURB-65: 1 point for confusion, urea >7, RR >30, BP <90/60, ≥65yo
hostology for TB
· Classic histology finding: caseating granulomas
Ix for TB different types what xo you find
o CXR: upper lobe cavitation, hilar lymphadenopathy, patchy consolidation
o Sputum samples x3
Microscopy on Ziehl-Neelson stain; culture on Lowenstein-Jensen medium for 6wks → acid fast bacilli seen. Gold standard for diagnosis
Bronchoalveolar lavage if unable to produce sputum
Auramine stain can be used to screen for TB however is not diagnostic
o Tuberculin skin tests (Mantoux/Heaf): Positive result seen in active and latent infection AND previous BCG vaccination
o Hospital-acquired Common pathogens =
Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and other nonpseudomonal Gram-negative bacteria are the most common causes.
Enterobacteriaceae (most common) such as the gram negs mentioned above: e coli, kelbsiela
community acquired pneumoina most commong bugs
Strep pneumoniae (most common), Haemophilus, Mycoplasma
pneumonia
Rusty-coloured sputum. Lobar on CXR
caused by what and give microscpe
strep pnuemoniae
+ve diplococci
pnuemonia
Assoc. w/ smoking, COPD. Most common cause of bronchopneumonia
caused by what and give microscope
Haemophlius influenza
-ve cocco-bacilli
pneumonia
Assoc. w/ recent viral infection (post-influenza) ± cavitation on CXR
caused by what and give ,microscope
staph aureus
+ve cocci clusters
pneumonia
Alcoholics, DM, elderly. Upper lobe cavitating lesion
Klebsiella
-ve rod (enterobacteriae)
pneumonia + Travel with stay in hotel, air conditioning, hepatitis, hyponatraemia
how do you diagnose ?
legionella pnuemophilia
daignosed with urinary antigen test
pneumonia –> Outbreaks in young people at school or university, dry cough, arthralgia
what is it ? how to diagnose ? how to treat?
Mycoplasma pneumoniae
cold agglutinin test / AIHA, erythema multiforme.
Treated best with tetracycline or macrolide
pneumonia seen Seen in people who keep birds
Chlamydia psittaci
resp infection with people who have HIV + how to treat and what do you see on xray ?
o Pneumocystis jiroveci (PCP). Desaturation upon walking around room, bat’s wing appearance on CXR, treat with co-trimoxazole
o TB
resp infection for someone with splenectomy
encapsulated organisms = H. influenzae, S. pneumoniae
patients with neutropenia get this resp infection
o Aspergillus. Interstitial CXR changes. Halo sign on CT scan
Risk factors for infective endocarditis
- Abnormal valves: prosthetic valve, rheumatic heart disease, congenital heart disease
- Bacteraemia: long-term lines (e.g. dialysis), IVDU, poor dentition / dental abscess
- Immunosuppression
most common pathogens in infective endocarditis
- Acute (high-virulence bacteria): Strep pyogenes (Group A Strep), Staph aureus (most common in IVDU), CoNS (most common in prosthetic valve)
- Subacute (low-virulence bacteria): Staph epidermidis, Strep viridans, HACEK
o HACEK organisms are uncommon causes and do not grow on culture → consider if high suspicion but culture -ve
Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella
ix for infective endocarditiis
Investigations:
* Blood cultures - >3x from different sites, ideally before starting Abx
* Echo
signs and sx of infective endocarditis
- Fever (most common symptom, often presents as PUO)
- Non-specific Sx: anorexia, weight loss, malaise, fatigue, night sweats, SOB, clubbing
- New heart murmur, often changes day to day, usually regurgitant
- In subacute:
o Embolic phenomena: Janeway lesions, splinter haemorrhages, splenomegaly, septic abscesses in lungs/brain/spleen/kidney, microemboli
o Immune phenomena: Roth spots, Osler’s nodes, haematuria (due to glomerulonephritis)
what criteria for infective endocarditis
modified dukes criteria
Clinical criteria: (BE TIMER)
Infective endocarditis = 2 major, OR 1 major + 3 minor, OR 5 minor criteria
Major
- Blood cultures positive (>2x >12hrs apart typical organisms consistent with IE)
- Endocardial involvement evidence i.e. new murmur, vegetation on echo
Minor
- Temp > 38 (fever)
- Immune phenomena (see above)
- Microbiological evidence not meeting major criteria
- Embolic phenomena (see above)
- Risk factors
o Embolic phenomena: Janeway lesions, splinter haemorrhages, splenomegaly, septic abscesses in lungs/brain/spleen/kidney, microemboli
o Immune phenomena: Roth spots, Osler’s nodes, haematuria (due to glomerulonephritis)
tx for infective endocarditids
- IV Abx for 4-6wks (use local guidelines)
o Start empirically after cultures taken, then change according to sensitivities
o Acute: flucloxacillin
o Subacute: benzylpenicillin + gentamicin
o Prosthetic valve: vancomycin + gentamicin + rifampicin (6w) - Surgical debridement for some patients
3 types of diarhhoea and causative organisms and explain each type
- · Secretory diarrhoea
o Toxin production → Cl- secreted into lumen → loss of water and electrolytes → D+V → Watery diarrhoea, no fever
o Cholera, ETEC, EPEC, viruses - Inflammatory diarrhoea
o Inflammation and bacteraemia → Bloody diarrhoea (dysentery), fever
o CHESS: Campylobacter jejuni, EHEC, Entamoeba, non-typhoidal Salmonella, Shigella - Enteric fever
o Unwell with fever, fewer GI symptoms
o Typhoidal salmonella, Yersinia, Brucella
if nitrite negative on urine dip what does this mean for pathogenic origin of uti ?
- Staphylococcus saprophyticus: common in young females. Note: E coli still most common among young women but if in question nitrites are negative, S. saprophyticus more likely
what do ou expect to see on urine dip for people with UTI ?
· Urine dip: +ve nitrites and leukocytes
o Nitrites are quite specific for UTI – if nitrites -ve, unlikely to be UTI
o Leukocytes are not specific (also seen in STI, bladder cancer, renal stones, catheters, TB)
o Note: do NOT use urine dipsticks in people with catheters or aged over 65 over as non-pathological bacteriuria common
if squamous epithelial cells present on urine mc&s what does it mean ?
contaminatoin
alsom if its says mixed growth as well
surgical site infection
most common organism and managemetn
S. aureus (MRSA + MSSA), E. coli, Pseudomonas
Abx: fluclox for Staph
osteomyletiis
most common organiusm and management
stpah aureus
IV Abx –> flucloxacillin (clindamycin if penicillin allergic), with consideration of the addition of fusidic acid or rifampicin for the first two weeks
If meticillin-resistant staphylococcus aureus (MRSA) is suspected, vancomycin or teicoplanin is recommended
septic arthritis
most common organism and managemtn
S. aureus (most common), Strep, E. coli, N. gonorrhoea if young
IV Abx- cephalosporin or flucloxacillin
Drain joint
ix for septic arthritis
Joint aspirate – MC&S. Synovial count >50,000 cells/mm³
Blood culture
Prosthetic joint infection
most common organism and management >?
Cogulase negative staph (most common), S. aureus, E. coli
IV Abx
Remove prosthesis and revise replacement
most common cause viral meningtisi
Viral: Enterovirus (coxsackie, echovirus)- most common cause of all meningitis, mumps, HSV2m
most common cause of all meningitis ?
Enterovirus (coxsackie, echovirus)- most common cause of all meningitis
most common cause of bacterila meningitis
N. menigitidis, S pneumoniae, H. influenzae. M. Tuberculosis
pathogens for meningitis in neonates
Group B Strep, Listeria monocytogenes, E. coli
pathogens for meningntis in yougn people
N. menigitidis, S. pneumoniae, H. Influenzae
pathogens for meninigtis in elderly
Group B Strep, Listeria monocytogenes
fungal meningits caus e?
Cryptococcus neoformans
how to manage meningitis (don’t forget the special add ons)
Management: Resuscitate! IV ceftriaxone and corticosteroids (unless meningococcal)
- Add ampicillin to cover Listeria if neonate or elderly
- If consciousness affected, consider IV acyclovir to cover encephalitis
avoid dexamethasone in septic shock, meningococcal septicaemia, or if immunocompromised, or in meningitis following surgery’
encephalitis
features, causes (+most common), ix, mx
Symptoms: confusion, fluctuating consciousness, focal neurology, seizures
Causes:
· Viral: HSV 2 (most common cause), Enteroviruses, Western Nile Virus
· Bacterial: Listeria
· Amoebic: Naegleria Fowleri, found in warm freshwater and thermal pools
· Parasitic: Toxoplasmosis Gondii
· Note: Encephalitis can also be autoimmune
Investigations: 1st line CT, lumbar puncture to identify causes if no ICP, MRI is gold standard
Management: 1st line- IV acyclovir
which STI’s give discharge ?
Gonorrhoea
Chlamydia
Trichomonas
Candida
Bacterial Vaginosis
which STI’s give rashes, lumps/ growths
Genital warts - HPV
Molluscum contagiosum
Scabies
Pubic lice
features, diagnosis and tx for gonorrhea
men = mucopurulent discharge
women = mucopurlent cervitis
Diagnosis: urethral/rectal smears – producing a culture from these is Gold Standard.
Treatment: Ceftriaxone IM – 250mg single dose
features , daignosis and tx for chlamydia
features –> often asymptomatic
Diagnosis: NAAT (nucleic acid amplification tests) from genital swabs
Treatment: azithromycin 1g stat, or doxycycline 100mg BD for 7 days
pathogen for syphhilis
Treponema pallidum – Obligate gram-negative spirochaete.`
syphilis tx
Treatment: Single dose IM Benzathine Penicillin (Doxycycline if allergic)
strawberry cervix
what pathogen and how to treat
Trichomoniasis vaginalis
· Men: usually asymptomatic, sometimes urethritis
· Females: discharge, strawberry cervix
Diagnosis: wet prep microscopy, (flagellated organisms seen), PCR
Rx: metronidazole
· Associated with increased risk of HIV infection (due to mucosal damage)
clue cells
bacterial vaginosis
discharge + odour from vagina - what is it?
·Abnormal vaginal flora, polymicrobial, ↓lactobacilli.
· Discharge, odour
· Sexually associated, not transmitted. Associated with hygiene practices (soaps)
·Diagnosis: microscopy of gram stain, raised pH, whiff test, clue cells which appear as stippled epithelial cells
Rx: lifestyle - just use water for washing (no soaps). Metronidazole PO/topical
candidiasis
what pathogen
features in men and women
give management
·Usually Candida albicans, yeast
· Thick white discharge (“cottage cheese”), itching, soreness, redness
· Vulvovaginitis in women, balanitis in men
· Not sexually transmitted; can be part of normal flora
· Associated with immunodeficiency (incl. pregnancy, DM), hygiene practices (soaps)
· Rx: Oral fluconazole or topical clotrimazole
Skin infection
which common organism therefore whihc abx?
S. aureus
Flucloxacillin (unless allergy)
pharingitis
which common organism therefore which abx?
β-haemolytic Streptococcus
Phenoxymethylpenicillin
community acquired pneumonia
mild and severe
Mild
Amoxicillin (or doxycycline)
Severe
Co-amoxiclav + clarithromycin
Sepsis
whcih abx
Severe
Tazocin / ceftriaxone, metronidazole ± Gent
Neutropenic
Tazocin + gentamicin
Colitis
which common organissm and which abx
Clostridium difficile Oral vancomycin
Natural reservoir of Influenza A is …`
ducks
2 methods viruses change
Antigenic Drift = Accumulation of point mutations (Due to error prone RNA polymerases) changes the nature of the antigen over time (drift).
Antigenic Shift = Recombination of genomic segments of two co-infecting flu strains -> leads to rapid potentially whole antigenic change for a viral strain (shift).
which antiviral for herpes simplex virus
aciclovir or valaciclovir
which antiviral for varicella zoster virus ?
aciclovir
Human Cytomegalovirus (HCMV) which antiviral
1st line Ganciclovir (IV)/ valganciclovir
2nd line Foscarnet (IV)
3rd line Cidofovir
Epstein-Barr virus (EBV) which aniviral
trick question
largely supportive
what does EBV cause ?
Glandular fever
· Triad of fever, pharyngitis, posterior cervical lymphadenopathy
· maculopapular rash
· fatigue
Note: Predisposes to Burkitt’s lymphoma
In immunocompromised:
Post-transplant lymphoproliferative disease (Predisposes to lymphoma. Treatment – reduce immunosuppression + give Rituximab (anti-CD20 monoclonal Ab))
Diagnosis- monospot for heterophile antibodies (Note also positive in CMV). Most sensitive and specific are EBV-specific antibodies
antiviral for inlfuenza virus
oseltamivir
Hep A
features, transmission route, diagnosis, management
· Acute hepatitis – fever, abdo pain, jaundice, malaise
· Faeco-oral transmission, recent travel to endemic nation
Diagnosis: Acute - Anti-HAV IgM
Largely supportive care
gold standard diagnosis for active infection of Hep B?
Hepatitis B surface antigen (HBsAg)
what defines chronic HBV infection in terms of serology?
HBsAg > 6 months
HBV transmission
bolidy fluids, MSM , IVDU, tattoo,
how does HCV manifest? and give how its diagnosed
· Mainly chronic disease (50% progress to chronicity)
· Severity mainly determined by genotype of virus
· Mainly blood product spread- transfusions, sharing needles
· Progresses to cirrhosis, liver failure and hepatocellular carcinoma
Diagnosis: Anti-HCV antibodies become active >4wks after infection. If suspect acute infection measure HCV RNA
oultine Hep D virus
Can only contract 2 ways:
· Co-infection simultaneously with Hep B
· Superinfection (on top of chronic) Hep B (more severe – often leads to cirrhosis within 2-3yrs)
Transmission: Sexual, parental, perinatal (only possible in combination with HBV)
outline Hep E virus
· Acute hepatitis, can only be chronic in immunosuppressed
· Faeco-oral transmission, most common in South and East Asia
· Main thing to know for exams is that if contracted in pregnancy, the disease can be very severe, often lethal
· Rare complications: CNS disease – Bell’s palsy, Guillain Barre, other neuropathy
Diagnosis: HEV IgM and IgG. Immunosuppressed HEV RNA
features of rubella virus
German measles
· Maculopapular rash which starts on face and spreads rapidly to body
· Lymphadenopathy
· Fever
· Lesions on soft palate (Forchheimer sign)
features of Human parvovirus B19
In children - slapped cheek/fifth disease/erythema infectiosum
· Bright red rash on cheeks
· Arthralgia
· Fever and malaise
In adults- flu-like illness
Diagnosis- serology for IgM for current infection
features of measles and name of virus ?
morbillivirus
Measles
· Fever, malaise
· Cough, coryzal symptoms, conjunctivitis
· Koplik’s spots (buccal mucosa)
· Maculopapular rash which starts behind ears and spreads to body over a few days
Diagnosis- clinical diagnosis but can use nasopharyngeal swab for PCR
features of mumps
· parotid swelling- painful and tender
· malaise
· fever
complications with mumps
· Epididymo-orchitis (can lead to infertility)
· Pancreatitis
· Meningitis
serology of carrier in HBV
this means they have chronic infection, they may be asymptoamtic
HBsAg positive
anti-HBsAg negative
IgM anti-HBc negative
anti - HBc antigen positive
they have surface antigen in their blood and they havent made antibodies to surface antigen yet but they have made antibodies to the core antigen ]
List the 5 main congenital infections and the memory aid to remember them
TORCH
Toxoplasmosis
Other (HIV , HBV)
Rubella
CMV
HSV
how does congenital toxoplasmosis present ? and how to manage ?
· Symptoms: Chorioretinitis, hepatosplenomegaly, jaundice, cerebral calcifications, microcephaly
· Can be asymptomatic at birth then present later with low IQ and deafness
· Mother often asymptomatic
· Management: pyrimethamine and sulfadiazine
how does congenital HIV present ?
· HIV- Asymptomatic until immunosuppression develops
how does congenital HBV present ?
Asymptomatic until later life when develops jaundice, abdo pain, dark urine and pale stool
how does congenital syphalis present ?
persistent rhinitis, hepatosplenomegaly, jaundice, maculopapular rash progressing to desquamation and crusting, Hutchinson teeth
common fetal defects with congenital rubella
PDA and catarcts
how does congenital HSV present ?
· Foetal infection from ascending genital maternal infection, greatest risk in 3rd trimester where offer c-section if within 6 weeks of birth
· 3 types of presentation
o Skin, eye, mouth disease- keratoconjunctivitis, vesicular rash on face
o CNS involvement- seizures, lethargy, irritable
o Disseminated- septic presentation often involving liver and lungs
· Treat with aciclovir
define pyrexia of unknown origin
> 38.3⁰C fever on several occasions persisting >3/52 without diagnosis despite >1/52 of intensive Ix.
which organisms for typhoid ? and how do you manage ?
· Salmonella typhi and paratyphi (anaerobic gram -ve bacilli)
· Management: IV ceftriaxone then PO azithromycin
how does typhoid present ?
· Causes enteric fever by infecting Peyers patches in intestines
o 5S’s: rose Spots, hepatosplenomegaly, solid stools, sphygmothermic dissociation (low HR + fever aka Faget’s sign)
dengue virus?
flavavirus
symptoms of dengue ?
· Symptoms: myalgia, fever, rash, retro-orbital headache. Reasonably mild + self-limiting
· If re-infected with a different serotype…
o Dengue haemorrhagic fever / dengue shock syndrome
o Can be associated with non-blanching rash
o Rare in travellers (as uncommon to be re-infected)
o Supportive management
most common subtype of malaria pathogen ?
Plasmodium falciparum: most common
tx for malaria ?
IV artesunate
erythema chronicum migrans
bulls eye rasj h - you get this in lyme disease
Yeasts Vs Moulds:
dimorphism – yeast during infection, mould in nature.
what causes ringworm?
Tricophyton rubrum
what causes atheletes foot?
Tricophyton rubrum
