Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Path > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What is the classical lesion seen in TB?

A

Caseating granulomas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Risk factors of TB?

A

Travel (South Asia and Eastern Europe)
HIV+
Homelessness
IVDU
Contact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Presentation of TB

A

General: fever, night sweats, weight loss
Respiratory: cough, haemoptysis

Less commonly..(seen in immunosuppression)
Subacute meningitis: headaches, personality change, meningism, confusion. Diagnose with LP
Spinal (Pott’s disease): back pain, discitis, vertebral destruction, iliopsoas abscess
Milliary TB: disseminated haematogenous spread (seen on CXR)
Also lymphadenitis, pericarditis, peritonitis, renal, testicular, liver TB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Investigations for TB?

A

CXR - showing upper lobe aviation (post-primary activation)

Sputum samples (x3): Ziehl-Neelson microscopy and 6 week Lowenstein-Jensen culture for acid-fast bacilli

IGRA - shows exposure (active or latent)

PCR (showing rifampicin resistance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

TB treatment (inc side effects)

A

Rifampicin (6 months) - orange secretions; cytochrome p450 inducer
Isoniazid (6 months) - peripheral neuropathy
Pyrazinamide (2 months) - hepatotoxicity, gout “painful joint”
Ethambutol (2 months) - optic neuritis

RIPE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Typical pneumonia organisms

A

Streptococcus pneumonia (most common); rust-coloured sputum, lobar on CXR; +ve diplococci

Haemophilus influenza; smokers and COPD; -ve cocco-bacilli

Morazella catarrhalis; smokers; COPD; -ve cocci

Staphylococcus aureus; recent viral infection ± CXR cavitation; +ve cocci “grape-bunch clusters”

Klebsiella pneumonia; alcoholics, elderly, haemoptysis; -ve bacillus, enterobacter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Atypical pneumonia cases

A

Legionella pneumophilia: Travel, air conditioning, water towers, hepatitis, hyponatraemia

Mycoplasma pneumoniae:
Uni students / boarding schools, dry cough, arthralgia, cold agglutinin test / AIHA, erythema multiforme

Chlamydia psittaci: Birds

Chlamydia pneumoniae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Respiratory tract infections in HIV patients?

A

Pneumocystis jirovecii pneumonia (PCP)
TB
Cryptococcus neoformans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Respiratory tract infections in patients with splenectomy?

A

Encapsulated organisms:
Haemophilus influenza
Streptococcus pneumoniae
Neisseria Meningitidis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Respiratory tract infections in cystic fibrosis patients?

A

Pseudomonas aeruginosa
Burkholderia cepacia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Respiratory tract infections in neutropoenic patients?

A

Aspergillus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the CURB-65 score?

A

Helps determine treatment for community-acquired pneumonia

Confusion
Urea >7
Respiratory rate >30
BP <90/60
≥65yo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pathogens in acute infective endocarditis?

A

These are high-virulence bacteria:

Streptococcus pyogenes (Group A Strep)

Staphylococcus aureus (common in IVDU)

Coagulase-negative staphylococci (common in prosthetic valve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pathogens in subacute infective endocarditis?

A

These are usually low-virulence bacteria:

Staphylococcus epidermis

Streptococcus viridans

HACEK (uncommon and culture -ve)
Haemophilus
Acinetobacter
Cardiobacterium
Eikinella
Kingella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the criteria for diagnosis infective endocarditis?

A

Duke’s Criteria (2 major OR 1 major + 3 minor OR 5 minor)

Major:
* Positive blood culture growing typical organisms (>2x cultures >12hrs apart)
* New regurgitant murmur or evidence of vegetation on echo

Minor:
* Presence of risk factors
* Fever >38ºC
* Presence of embolic phenomena
* Presence of immune phenomena
* Positive blood cultures not meeting major criteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Common UTI organisms

A

E. coli (most common) - adhesion with fimbriae

Staphylococcus saphrophyticus - common in young females

Proteus, Klebsiella - in abnormal urinary tracts

Staphylococcus aureus - via haematogenous spread

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is antigenic drift?

A

Accumulation of point mutations due to error prone RNA polymerases which changes the nature of the antigen overtime

18
Q

What is antigenic shift?

A

Recombination of genomic segments of two co-infecting flu strains –> leads to potential rapid whole antigenic change for a viral strain.

Potentially allows exchange of RNA segments between human and animal strains

19
Q

Antivirals used for influenza

A

Amantadine (M2 ion channel targeted)

Baloxavir (polymerase inhibitor)

Oral oseltamivir, inhaled zanamivir, IV peramivir (neuroaminidase inhibitor)

20
Q

Congenital infections in neonates

A

TORCH

Toxoplasmosis
Other (HIV, HBV)
Rubella
CMV
HSV

21
Q

Causes of early onset sepsis (<48hrs) in neonates

A

Primary: Group B streptococci

Others: E. coli, Listeria

22
Q

Causes of late onset sepsis (>48hrs) in neonates

A

Coagulase negative staphylococcus

GBS

E. coli
Listeria

23
Q

Organisms that cause bacterial meningitis

A

Neisseria meningitidis (non-blanching petechial rash) - most common >3 months of age

Streptococcus pneumoniae - <2yr old

Haemophilus influenzae - <3 months old and unvaccinated children

GBS, E.coli, Listeria - common in 1-3 months so give amoxicillin (empirical Abx)

24
Q

Organisms that cause UTIs

A

Primary: E. coli

Proteus
Klebsiella
Enterococcus

*Need to culture >10^5/ml

Will see pyuria (pus cells) on microscopy

25
Q

Causes of neutropenic picture/pyrexia of unknown origin

A

Chemotherapy
Haematological malignancies
Drugs like clozapine, carbimazole

26
Q

Typhoid fever

A

Caused by salmonella typhi and paratyphi (gram -ve bacilli)
Transmitted in food and water, with incubation 1-2weeks
Causes enteric fever –> infects Peyers Patches in intestine

Symptoms include:
*Fever
*Constipation
*Rose spots
*Headaches
*Relative bradycardia
*Hepatosplenomegaly

Treat with IV ceftriaxone, then PO azithromycin

27
Q

Dengue

A

Caused by flavivirus, spread by Aedes mosquito
Short incubation period (days)

Symptoms include:
*Myalgia
*Fever
*Rash

Reasonably mild and self-limiting however…
can cause dengue hemorrhagic fever or dengue shock syndrome if re-infected with a different serotype

28
Q

Malaria

A

Protozoal infection (plasmodium) spread by female anopheles mosquitos
Life cycle involves mosquitos and humans (RBCs and liver)

Classified by species - Falciparum vs. non-falciparum
P. falciparum - most common and most severe (admit to hospital)
Non-falciparum (less severe with outpatient management) - P. vivax, P. ovale, P. malariae, P. knowlesi

29
Q

Non-falciparum malaria blood film and treatment

A

Schüffner’s dots on blood film

Either an oral artemisinin combination therapy (ACT), or chloroquine

30
Q

Falciparum malaria blood film and treatment

A

thick and thin blood films - thick detects malaria whilst thin detects species

Mild treatment - artemisinin combination therapy (ACT) which uses Artemetherelumefantrine. If unavailable, quinine or atovaquone eproguanil can be used

Severe treatment - IV artesunate. If unavailable, use IV quinine

31
Q

Brucellosis

A

Gram -ve aerobic bacilli (facultative intracellular)

Transmission - contaminated food (untreated milk/dairy) and direct animal contact

Presentation - undulant fever (peaks in evening), myalgia, arthritis, spinal tenderness, hepatosplenomegaly, epididymo-orchitis

Serology - anti-O-polysaccharide antibody, WCC normal/neutropenia

Treatment - doxycycline + streptomycin (expensive) or Rifampicin (cheap) for 4-6 weeks

Complications - endocarditis, osteomyelitis, meningoencephalitis

32
Q

Rabies

A

Rhabdovirus

Transmission commonly through dogs and bats

Presents in 3 phases:
1) Prodrome - fever, headache, sore throat
2) Acute encephalitis (hyperactive state)
3) Migration to CNS (after months-years) –> fatal encephalitis, hyper salivation, hydrophobia

Serology - IgM Negri bodies

Treatment - rabies IgG post-exposure treatment (before symptoms) + full rabies vaccination course

33
Q

Plague

A

Yersinia pestos, gram -ve lactose fermenter

Transmission by fleas with reservoir in rats

Presents with:
1) Bubonic plague (most common) - flea bites human, swollen tender lymph nodes (buboes), dry gangrene
2) Septicaemic plague - flea bite or direct contact on to broken skin, DIC causing haemorrhage, necrosis with purpura and gangrene, no lymph node involvement
3) Pneumonic plague (least common) - epidemic with person-person spread

PCR test to confirm

Treatment - Streptomycin, doxycycline, gentamicin, chloramphenicol (in meningitis)

34
Q

Leptospirosis (Weil’s disease)

A

Leptospira interrogans, Gram -ve

Transmission - excreted in dog/rat urine, with penetration of broken skin or swimming in contaminated water

Presentation - high fever, conjunctival haemorrhages, jaundice, meningism, renal failure, haemolytic anaemia

Treatment:
Not critically ill - doxycycline or azithromycin (within 48hrs)
Mild to moderate - amoxicillin or ampicillin
Severe (requiring hospitalisation) - IV penicillin G

35
Q

Anthrax

A

Bacillus anthracis, gram +ve spore forming

Routes of infection - cutaneous (95%), inhalation (pulmonary), intestinal, injection

Presentation of cutaneous - ulceration of black vesicular lesion with surrounding oedema. Usually affects hands, face, forearm and neck

Presentation of inhalation - massive lymphadenopathy with flu-like symptoms + mediastinal haemorrhage

Treatment - doxycycline or ciprofloxacin, combined with another antibiotic of choice

36
Q

Lyme disease

A

Borrelia burgdorferi (spirochaete), which is anthropode-borne

Transmission - lxodes ticks which are infected by B. burgdorferi

Presentation:
1) Early - erythema chronic migrans (bullseye rash), flu-like
2) focal neurology, neuropsychiatric, arthritis

Investigations - biopsy edge of rash + perform ELISA for Lyme Abs

Treatment - Doxycycline 2-3 weeks (or amoxicillin or cefuroxime). If present with neurological symptoms, consider IV Abx

37
Q

Q fever

A

Coxiella burnetii, gram -ve parasite

Transmission through farm animals (cattle and sheep)

Presentation - atypical pneumonia (dry cough, fever), no rash, hepatitis, erythema nodosum

Serology - rise in phase II IgG through IFA

Treatment - doxycycline

38
Q

Leishmaniasis

A

Infection of trypanosomatid protozoan: Leishmania

Transmission by female phlebotomine sandflies

Presentation:
1) Cutaneous (most common) - erythematous patches at bite –> painless ulceration –> multiply in dermal macrophages –> heals after 1yr leaving depigmented scar

2) Diffuse - patients with immunodeficiency, nodular lesions that spread around body

3) Mucocutaneous - New World sandfly species, dermal ulcers like cutaneous presentation. Months to years later, patient presents with ulcers in mucous membranes of nose, mouth and throat

4) Visceral (aka Kala Azar) - usually young malnourished child. Abdominal discomfort and distension (marked hepatomegaly and enormous splenomegaly) with fever, weight loss and anorexia. Can also present with anaemia, pancytopenia and hypergammaglobulinaemia.
Specifically in Leishmania Donovan - invasion of reticuloepithelial system –> hepatosplenomegaly + bone marrow invasion –> disfiguring dermal disease (aka PKDL)

Treatments (many) - includes antimony compounds, miltefosine, amphotericin, paromomycin, fluconazole, pentamidine and more…

39
Q

Types of fungal infection

A

Superficial - diagnosed with wood lamp:
1) Tinea
2) Pityriasis

Deep seated - diagnosed clinically, lab results and imaging:
1) Candida
2) Aspergillus (ABPA, invasive aspergillosis, aspergilloma)
3) Cryptococcus (particularly in HIV)

40
Q

Class, target and indication of antifungals

A

Polyene (e.g. amphotericin) - cell membrane integrity - yeast

Azole (e.g. fluconazole) - cell membrane synthesis - yeast

Terbinafine - cell membrane - mould (vs dermatophytes)

Flucytosine - DNA synthesis

Echinocandin (e.g. caspofungin) - cell wall - yeast (less toxic SE)

41
Q

What is prion disease?

A

Protein-only infectious agent which causes rare transmissible spongiform encephalopathies in humans and animals –> rapid neuodegeneration and death in months

Most common is CJD (Creutzfeldt-Jakob Disease)

Pathophysiology: due to abnormal folding of protein PrP to cause beta-sheet configuration + protease/radiation resistance. This eventually causes it to become insoluble

Inherited prion disease is caused by PNRP gene mutation and codon 129 polymorphism - 3 types MM, VV or MV

42
Q

Creutzfeldt-Jakob Disease (CJD)

A

see lecture on prions. very difficult help

Path (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions