Others - Mycoplasma/Chlamydia/Mycobacterium/Obligate Intracellular Pathogens Flashcards
Why is Gram stain not used for Mycoplasma?
It has no cell wall and hence cannot be visualised via gram stain. This also results in its resistance to cell wall synthesis inhibitors.
Clinical presentation of M. pneumoniae?
URTIs - Walking pneumonia (Mild pneumonia where patients are mobile and can continue spreading disease)
Clinical presentation of M. hominis and U. urealyticum?
Non-gonococcal urethritis, UTIs
Treatment for Mycoplasma?
Erythromycin
Why do we not use Gram stain for Chlamydia?
Little peptidoglycan in cell wall, unable to visualise clearly. Resistant to cell wall synthesis inhibitors.
How is Chlamydia classified?
By surface antigens
How is C. trachomatis (A-C) spread and is there immunological memory?
Spread via 3Fs (Flies, fingers, fomites). No immunological memory, could lead to repeated infections
Clinical presentation of C. trachomatis (A-C)?
Trachoma
- Chronic inflammation of eyelids -> Curling of eyelashes -> Cornea infection
- Pannus formation -> Blindness
How does C. trachomatis (L1-L3) spread?
Sexually transmitted
Clinical presentation of C. trachomatis (L1-L3)?
Lymphogranuloma venerum
Primary lesion on genitalia that can spread via lymphatics and cause rectal strictures and elephantiasis
Clinical presentation of C. trachomatis (D-K)?
STD
Males: Urethritis, dysuria (possible), infection of epididymis or rectum (homosexual males)
Females: Endocertival canal infection that could cause opthalmia neonatarum, ascending infection to cause reactive arthritis or urethritis/proctitis
How is Chlamydia trachomatis treated?
Doxycycline
Testing for C. trachomatis is done in conjunction with which other bacteria?
N. gonorrhoeae
Ch. pssitaci is spread by ___ and initially causes ___ that can lead to ___
Birds, flu-like illness, pneumonia and meningitis
Ch. pneumoniae causes a mild form of ___
Community acquired pneumonia
What stains are used for Mycobacterium?
Ziehl Neelsen Stain (ZN Stain) and Auramine stain (fluorescent microscopy)
Acid-Fast Bacilli culture (Takes 8 weeks)
Clinical presentations of M. tuberculosis?
Primary TB: Primary infection with foci in lower part of upper lobe or upper part of lower lobe (Ghon focus). Usually clinically silent.
Secondary TB: Reacitvation/reinfection -> Large exuberant granulomas with caseous necrosis (Assman’s focus)
Miliary TB: Disseminated by blood systemically
General symptoms of M. TB?
Fever, chronic cough with blood, night sweats, pulmonary disturbances, enlarged lymph nodes, possible joint and bone involvement
Treatment for M. tuberculosis?
RIPES
Rifampicin, Isoniazid, Pyrazinamide, Ethambutol, Streptomycin
Clinical presentation of M. leprae?
General presentation: Paralysis, anaesthesia, trophic ulcers, Charcot joints
Tuberculoid leprosy: Th1 response
Lepromatous leprosy: Th2 response
Which cells do Rickettsia affect and damage?
Endothelial cells
Which cells does Coxiella replicate in?
Phagolysosomes inside marcophages
Clinical presentation of Rickettsia?
General presentation: Fever, haemorrhagic lesions and possible shock due to vascular damage
Typhus type: Spread by lice
Spotted Fever: Spread by ticks
Scrub typhus type: Spread by chigger
Treatment for Rickettsia?
Doxycycline
How is Coxiella spread?
Airborne droplets or drinking infected milk
Clinical presentation of Coxiella?
Acute Q fever: Increased susceptiblity to viral infections
Chronic Q fever: Endocarditis (culture negative endocarditis)
Treatment for Coxiella?
Doxycycline
B. recurrentis causes ___ due to ___. Diagnosed by ____ and is treated with ___
Relapsing fever, constant antigenic variation, peripheral blood film, doxycycline
Borrelia burgdorferi causes ___ with ___. Diagnosed by ___ and is treated with ___.
Lyme disease, erythema chronic migrans, serology, doxycycline
How does Treponema palladum look like?
Thin helical spiral bacteria
Clinical presentation of Treponema palladum?
Primary syphilis: Painless chancre at cervix/penis with enlarged lymph nodes
Secondary syphilis: Diffused rashes across palms and soles, warty lesions (condylomata lata) at moist areas
Tertiary syphilis: Cardiovascular syphilis, meningitis, gummatous syphilis etc.
Congenital syphilis: Hutchinson’s triad
What is characteristic of congenital syphilis?
Hutchinson’s Triad:
1. Deafness
2. Interstitial keratitis of cornea
3. Notched incisors (Teeth)
Treatment of Treponema Pallidum?
Benzylpenicillin
Leptospira is chronically excreted in ___ and enters via ___.
Rat urine, exposed mucosa
Clinical presentation of Leptospira?
Phase I: Septicaemia, Phase II: Immune
Bacteraemia leptospirosis: Flu-like fever that will lead to aseptic meningitis
Icteric leptospirosis: Often fatal with haemorrhage, jaundice and renal failure
What is another name for Icteric Leptospirosis?
Weil’s disease
Helicobacter Pylori infects ___ in humans
Gastric mucosa
Treatment for Leptospira?
Benzylpenicillin
Clinical presentation of Helicobacter Pylori? Associated with?
Chronic inflammation predisposes to peptic ulcers and cancer
Causes dyspepsia, abdominal pain, flatulence, bad breath
Associated with MALT lymphoma
Treatment for H. pylori?
Quadruple therapy: Omeprazole, Clarithromycin, Metronidazole, Bismuth
Virulence factors of H. pylori
___ structure allows it to burrow into mucosa, preventing flushing away by gastric motility
Produces ___ that breaks down ___ to form ___, allowing it to persist in ___ environment
Produces ___ that causes ___ and ___ and ___
Proteases release damage gastric mucosa and release nutrients for continued colonisation
Spiral
Urease, urea, NH3, acidic
Bacterial PAF, local vasoconstriction, thrombotic occlusion, reduced mucosal regeneration
Campylobacter appears like a ___ in microscopy
Seagull
Campylobacter’s mode of transmission?
Faecaloral transmission via infected poultry
Clinical presentation of Campylobacter? Complications?
Incubation period that presents with initial flu-like illness that can cause abdominal pain and diarrhoea
Complications: Guillain-Barre Syndrome
What is Campylobacter sometimes misdiagnosed as?
Appendicitis
Treatment of Campylobacter?
Erythromycin
Types of Mycobacterium Leprae
- Tuberculoid leprosy (Th1)
- Lepromatous leprosy (Th2)
Test for Mycobacterium TB
Mantoux test
*CANNOT use Gram stain (Can use AFB or Auramine stain)
Primary TB is characterised by ___ and ___. Is often ___.
Ghon focus = small foci of inflammation comprising several MTC surrounded by a dense granuloma
Primary complex = Ghon focus + enlarged regional lymph notes
Clinically silent
Post Primary TB is due to ___ or ___. Can present in ___ in the body and presents as ___ with ___. Necrotic foci in lungs can be coughed out leading to ___.
Reinfection, reactivation
Any organ
Large exuberant granulomas, central caseous necrosis
Cavitations
Miliary TB occurs when bacteria is spread through the ___ and affects ___. Seen as ___ that show up well on ___ but not on ___.
Bloodstream, multiple organs
Small white nodules (millet seeds), CT, X ray
Clinical symptoms of TB
- Pulmonary: Chronic cough, sometimes bloodstained with dyspnoea
- CNS: Meningitis
- Osteomyelitis and vertebral collapse
Systemic features: Fever, night sweat and weight loss
MTC are phagocytosed by ___, but survive and continue to replicate within the ___. They inhibit acidification by producing a ___. More monocytes are recruited but ___. ___ are also recruited, releasing ___ that causes increased activity of macrophages that kill microbes. Could lead to ___, ___, or ___.
Macrophages, phagolysosomes
Cord factor
Unable to kill the microbes
Activated T lymphocytes, IFN-gamma
Cure, latency or active TB
What is TB misdiagnosed as?
Paragonimus westermani (lung fluke)
