Legionella, Mycoplasma, Chlamydia Flashcards
(21 cards)
What do Legionella, Mycoplasma, and Chlamydia have in common?
Atypical pneumonia and all are intracellular
Legionella pneumophila
Gram Shape Oxygen use What culture does it grow on? Disease
Two clinical syndromes?
Gram (-) - but doesn't stain well Bacillus Aerobic Charcoal yeast culture w/ iron and cysteine Atypical pneumonia
Legionnaires’ disease and Pontiac fever
Host risk factors for Legionella infection
Cigarette smoking, chronic lung disease, increasing age, transplant status, immunosuppressed
Symptoms of Legionnaires’
Fever, chills, myalgias, cough, vomiting, diarrhea, altered mental status, thrombocytopenia, hyponatremia (more prominent than in other pneumonias)
Symptoms of Pontiac fever
Fever, chills, malaise, headache, minimal or no respiratory symptoms
Diagnosis of Legionella
Urinary Legionella antigen - only disadvtg is it tests for only one serogroup
Serology, PCR not really recommended
Treatment of Legionella
Newer macrolides (azithromycin), respiratory fluoroquinolones (levofloxacin)
What is the smallest organism that can survive alone in the world?
What’s unique about it?
Mycoplasma - intracellular
No cell wall, only plasma membrane, so it is resistant to antibiotics that affect cell wall and can’t be found with Gram stain
Mycoplasmas that cause human disease
M. pneumoniae (main one)
M. hominis
M. genitalium
Ureaplasma urealyticum
M. pneumoniae
Transmission?
Symptoms?
Types of patients?
Infected respiratory droplets from close contact
Fever, headaches, malaise, cough, pharyngitis, rhinorrhea (most do NOT develop pneumonia)
Tends to infect children and young adults
Extrapulmonary manifestations of Mycoplasma?
- Hemolysis - cold agglutinin disease (RBC’s aggregate in cold temp)
- Dermatological - Erythema multiforme/Stevens-Johnson
- CNS - encephalitis
- Cardiac
- Bullous myringitis*****
Diagnosis of Mycoplasma
DIFFICULT - most are not practical
PCR of nasopharyngeal sample is best option
Treatment of Mycoplasma
Macrolides - Azithromycin most active, Doxycycline, respiratory fluoroquinolone (levofloxacin, moxifloxacin)
Two genuses of Chlamydia?
Chlamydia, Chlamydophila
Chlamydia species that cause human disease?
C. trachomatis - STD
C. pneumoniae
C. psittaci
C. trachomatis
Oxygen use?
Genome size?
Diseases?
Obligate intracellular
Smaller than any other prokaryote besides Mycoplasma
Conjunctivitis and pneumonia in neonates
Spectrum in teenagers/adults: affects genital region, lymphogranuloma venereum (LGV)
Unique reproductive cycle of Chlamydia includes what two forms? Which one spreads to neighboring cells?
Elementary bodies and reticulate bodies
Elementary bodies spread and invade
What is lymphogranuloma venereum? What are the two stages?
Ulcerative genital infection - disease of lymphatic system
Stages:
- Primary - genital ulcer
- Secondary - significant inflammatory reaction in inguinal lymph nodes –> “groove sign”
C. pneumoniae
Types of patients? Disease?
Symptoms?
Diagnosis?
Treatment?
Elderly - community-acquired pneumonia
Systemic symptoms w/ mild respiratory symptoms
DIFFICULT - can’t really culture it, can use acute and convalescent titers, but not immediate or practical; also wide spectrum of clinical presentation (mild - severe)
TREATMENT - doxycycline, but newer macrolides (azithromycin) used for empirical treatment of atypical pneumonia, can also use fluoroquinolones (levofloxacin)
C. psittaci
Disease? Zoonotic vector? Symptoms? Type of patient? Diagnosis Treatment
Psittacosis - parrot fever
Birds - all kinds
Fever, dry cough, myalgias, headache, usually respiratory symptoms
Most common in young people
Diagnosis - CXR abnormal in most, culture discouraged b/c it’s so infectious
Treatment - choice = tetracyclines (doxycycline), also macrolides (azithromycin)
WBC count in atypial pneumonia - typically normal or abnormal?
Normal
