23 Nontuberculous Mycobacteria, Nocardia, Legionella and Mycoplasma Flashcards by Katelynn Davis

What is the second most common mycobacterial disease? Can it survive outside of a host?

M. leprae- Hansen’s disease

- must be in a host

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T-F-it is not important for treatment and public health to distinguish between NTM infection and one from M. tuberculosis?

False

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T-F–non-tuberculous mycobacterium can cause disease in immune privileged individuals only?

False- healthy too

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Large disfiguring lesions that are often painless are from what? What does it secrete that leads to nerve damage, immunosuppression and necrotizing adipose? Opportunistic or primary pathogen?

M. ulcerans

secretes mycolactones
It is an opportunistic pathogen

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What often survives in biofilms in water supplies, cooling towers, fountains?

Legionella

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What must legionella survive in in the natural world?

Inside amoeba or other protozoan inside the water

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What are the 2 main forms of legionella?

replicative stage and mature intracellular form

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T-F–detection of legionella in the water is definitive for an upcoming outbreak?

false- outbreak strains must be genotypical matched to strains found in the water supply

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How are humans infected by legionella?

Droplets and survival occurs in macrophages

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What is the unculturable bacteria? Does it have a cell wall? Significance?

Mycoplasma
no cell wall
no beta-lactam antibiotics

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What is the most common cause of community acquired pneumonia?

Mycoplasma pneumoniae

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What is the main virulence factor of mycoplasma?

adherence- p1

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T-F– most cases of M. ulcerans are transmitted person to person?

False

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M. leprae is an infection of what? 5

skin, peripheral nerves, upper respiratory, eyes

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Is numbness common in M. leprae? Why? Where does it start?

Yes 90%—there is significant nerve damage that leads to loss of sensation—begins in the extremities

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Transmission of M. Leprae is done by droplets, but what is required?

Prolonged, close and frequent contact

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Is risk of M. leprae higher with HIV?

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M. leprae can be found in a paucibacillary form/stage and multibacillary form/stage. What are the 2 characteristics of each that differentiate?

Paucibacillary= low acid fast bacilli and intact cell-mediated immunity

Multibacillary= High AFB and symmetrical skin lesions

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T-f–we have seen a dramatic increase in world disease burden of M. leprae?

False

[pockets are in Brazil China, Africa, Nepal, Philippines and Sri Lanka]

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How long can the M. leprae be latent for? What is the doubling time?

30 years

- 12-14 day doubling time

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What are the 3 main reservoirs of M. leprae?

human
nine-banded armadillo
[chimp, mangabey, monkey]

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What does leprosy diagnosis entail? 3

clinical signs/symptoms
AFB microscopy
Cannot be grown in culture

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Where does M. leprae survive?

Macrophages and non-phagocytic cells (striated muscle, glial, schwann)

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What is the multi drug treatment of M. leprae? Can M. bovis BCG be a good vaccine?

dapsone, rifampicin, and clofazimine for 6-12 months

2. yes but not pursued heavily

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T-f--m ulcerans is fast growing? has high mortality? and high morbidity?

False- slow growing False- low mortality True- high morbidity

Because m. ulcerans lesions are painless, most don't cause serious permanent damage?

False--loss of limbs and organs

What is the % of m. ulcerans cases found in children? How many of those are disabled?

75% and 60% of those are disabled

What environment is conducive to m. ulcerans infections?

rural tropics, near stagnant water

What is the characteristic histopathology of M. Ulcerans? how long do you have to culture? anything more sensitive?

1. extracellular acid fast bacilli 2. 6-8 weeks 3. PCR for IS2404

What are 5 characteristics of mycolactones?

``` Diffusable Many varieties Necrotizing Adipose Immunosuppressive Nerve Damage ```

What antibiotic treatment is given for M. ulcerans? Other treatment plans/options

- Rifampicin and streptomycin- 8 weeks | - surgery +/- grafting, self heal, BCG vaccine

What bacteria…opportunistic, symptoms 2-4 weeks post infections, arthritis, aquatic trauma, natural host is fish or frogs?

M. marinum

Is M. avium, M. intracellulare and M. kansasii fast growing?

No-slow

Is M. fortuitum, M. chelonae and M. abscessus slow growing?

No- rapid

What are the Runyon groups I-IV?

I=photochromogens II=scotochromogens III=nonphotochromogens IV= fast growers

What is the M. avium complex MAC? what common type of infections? where are infections coming from?

1. M. intracellular and avium 2. pulmonary infection in immunocompromised (can have GI infections too) 3. environmental sources- no person to person

For NTM infections what are the 4 common laboratory tests to speciate?

1. biochemical tests 2. Molecular probes 3. DNA sequence (16sRNA, genome) 4. Matrix-Assisted laser desorption/ionization-time of flight MALDI-TOF

What is a ubiquitous aerobic filamentous bacteria that is saprophytic and lives in soil or water?

Nocardia > 50 species

T-F Nocardia is a primary pathogen?

False--needs severely immunocompromised host

80% of nocardia presents as? other 20%?

80%- invasive pulmonary, disseminated, brain abcess | 20%- cellulitis

Which nocardia species is most responsible for invasive infections? cutaneous infections?

invasive=asteroides | cutaneous=brasiliensis

What does gram stain of nocardia look like? Acid fast stain?

gram-stain= weakly positive rods/filaments Acid fast stain=positive [differentiates from actinomyctetes] [it is important to note that Nocardia must be suspected to culture]

What is the drug therapy [3] for Nocardia? Resistance is a growing concern…which strain is of resistant?

1. Sulfonamide, ceftriaxone, amikacin | 2. N. farcinica

Why isn't Nocardia colonization in the laboratory not necessarily sign of invasive infection?

can mean laboratory contamination, may exist as saprophytes on the skin and upper respiratory tract

What is an aerobic, gram-negative rod, slow growth on BYCE media bacteria? colony appearance?

Legionella | -colonies look like ground glass

Is legionella opportunistic? how many species? serogroups?

yes, 48, 90

What legionella species is reported in 90% of cases?

legionella pneumophila

What is interesting about many of the species names of legionella?

named after outbreak location

How do we know a legionella like amoeba pathogen is not legionella?

they do not grow on culture

What is the reservoir of legionella?

acquatic environment - biofilms on manmade - intracellular in amoebas in natural lakes etc.

When does transmission occur for legionella? | replication?

- limited nutrients | - abundant nutrients

2 modes of acquiring legionella from the environment? person to person?

inhalation and aspiration | no person to person

What are the risk factors for legionella infection?

- Immunocompromised - heavy smoker - over age of 50 - recent travel

Is pontiac fever or légionnaires self limiting and non fatal respiratory infection?

pontiac

What are the symptoms of legionnaires and how many deaths in US?

fever, myalgia, cough pneumonia | 8000-18000

How to diagnose legionella?

``` Direct Fluorescent antibody Urine antigen PCR Culture Buffered Charcoal Yeast Extract (BYCE) [Must have culture plus UA or PCR] ```

What type of antibiotics are needed for legionella? drug of choice for kids?

high intracellular concentrations | azithromycin

What favors amplification in nosocomial legionella disease?

old and complex plumbing systems

Does legionella survive in 50-55C? 60C?

Yes, No [optimum is 35-45]

What are 5 characteristics of the Mollicutes class because they don't have a cell wall?

1. fragile 2. don't gram stain 3. contain mammal like membrane 4. No particular morphology 5. can not be treated with cell wall active drugs

What mycoplasma causes bacterial vaginosis?

Mycoplasma hominis

What mycoplasma causes urethritis?

genitalium, and urealyticus

What does mycoplasma fermentans cause?

flu-like illness and pneumonia

What 3 diseases does mycoplasma pneumonia cause?

1. Primary atypical pneumonia 2. Tracheobronchitis 3. Pharyngitis

T-f--mycoplasma pneumoniae has a short incubation period and long period of infectivity?

False- both are long periods

Does M. pneumoniae demonstrate seasonality?

What is the most common cause of pneumonia between 5 and 20 years?

M. pneumoniae

What are the onset symptoms of M. pneumoniae pneumonia? later symptoms?

onset=fever, headache, sore throat, non-productive cough!!, and malaise Later= paroxysmal cough, pain , blood maybe

Chest x ray appears as what in M. pneumoniae? What is the traditional testing for diagnosis?

1. striking consolidation which is odd for unremarkable lung sounds 2. serological testing or cold agglutinin but is not generally performed

Where does M. pneumoniae adhere? how

Base of cilia, P1 adhesion

What are common antibiotics for M. pneumoniae?

doxycline, macrolides, or fluoroquinolones