Infection Caused by Acid Fast and Higher Bacteria

What lipids are only found in the mycobacterium genus

Mycolic Acids

What are is the characteristic of mycobacterium cell wall

Waxy, hydrophobic

What is the characteristic of acid fast bacteria

Ability to resist decoloration by acids

What are AFB cell walls resistant to

Environmental stresses, disinfectants, usual stains and acid, nutrient uptake, host defense, antibiotics

What genuses display acid fastness

Genus mycobacterium and Genus Nordcardia

How is acid fastness diagnosed

Acid fast stain + microscopic examination, biochemical tests + molecular diagnostic test

Which acid fast stain does Myobacterium use

Acid fast stain

Which acid fast stain does Norcardia use

Modified Acid fast stain

What is the primary dye used in acid fast

Carbon fuchsin

What is the counter stain used in acid fast

Methylene blue

When a non acid fast bacterium is dyed with a counter stain, what color would it turn

From Red (from the primary dye) to blue

What color does acid fast bacteria by counter stain

Remains red

What is used as the decolorizer in acid fast

3% HCL in 95% ethyl alcohol

What decolorizer is used for a modified acid fast stain

1% H2SO4 in 95% ethyl alcohol

What color would a non acid fast bacteria turn after being exposed to decolorizer

Colorless

What is the difference between the KInyoun and Ziehl-Nielsen acid fast methods

Kinyoun is cold, Ziehl Nielsen is hot

What bacteria does NOT grow on media

M leprae

1-9 AFB in 100 fields

Report actual number of AFB seen

10-99 AFB in 100 fields

Report as 1+

1-10 AFB per field (at least 50 visual fields)

Report as 2+

>10 AFB per field (at least 20 visual fields)

Report as 3+

Auramine Method 1-2 ARB in 1 length

Confirm before reporting

Auramine 3-24 AFB in 1 length

Record actual number

Auramine 1-6 AFB in 1 length

Report a 1+

7-60 AFB per field in 1 length

Report as 2+

>60 AFB per field 1 length

Report as 3+

What can acid fastness also be attributed to

Structures that are NOT bacteria; eg endospores, head of sperm etc

What is the pathogenesis of MTBC

Internalized in phagolysosome → MTBC inhibit acidification → Hemolysin cause lysis → Escape out of macrophage → Granuloma formation → Fibroblast surround and cause caseous necrosis

What is Mtb

Causes TB, AEROBE, has mycolic acid, grows slowly, cordlike, cause delayed hypersensitivity

How is Mtb transmitted

Droplet which goes to bronchus

Clinical features of Mtb

Weight loss, night sweats, malaise, anorexia, fever

Mtb Lab diag

sputum, CSF, lymph node, gastric aspirate samples; AFB and cultivation or phenotypic DST, amplification

What are MOTT/ NTM

Mycobacteria that are not TB

Positive niacin test

Yellow color; mycobacterium positive

Positive Nitrate reduction test

White to red; mycobacterium positive

Positive Citrate utilization test

Green to blue; positive mycobacterium

Positive Tween 80 test

Orange to pink; positive mycobacterium

Iron uptake from medium meaning

Mycobacteria present and take up iron from media

Positive tellurite reduction test

Black precipitate; mycobacterium positive

Positive Urea hydrolysis test

Yellow to red; mycobacterium positive

What color do group I (photochromogens) atypical mycobacteria produce

Yellow orange

What color do group II (scotochromogens) atypical mycobacteria produce

Color in the dark

What color do group III (nonchromogens) atypical mycobacteria produce

Barely any with/without light

What is are group I atypical mycobacterium

M. kansasii and M. marinum

What is M. kansasii

Cause lung disease like TB; cause pulmonary, cervical lymphadenitis, cutaneous disseminated infeciton

What is M. marinum

Swimming pool granuloma/fish tank granuloma; causes granulomatous lesions on skin

What M species in Group II atypical mycobacterium

M. scrofulaceum

What is M. scrofulaceum

Causes scrofula (granulomatous cervical adenitis in children); goes from oropharynx into lymph nodes; in SOIL, WATER and RAW DAIRY

What species in group III atypical mycobacterium

M. avium, intracellulare complex (M. avium and M. intracellulate) and M. ulcerans

What is the characteristic of group III atypical mycobacterium

Difficult to distinguish, cannot be diff from TB, found in immunocompromised patients; anti TB drug RESISTANT

What is M avium

Inhalation or ingestion of contaminated food; causes cervical lymphadenitis

What is M ulcerans

Cause buruli ulcer; no fevers or malaise

What is Group IV mycobacterium

Rapidly growing; rarely cause disease; resistant to anti Tb drugs; skin and soft tissue infection

What species in group IV mycobacterium

M fortuitum chelonae complex (M. fortuitum and M. chelonei)

What is M. fortuitum

Grows in damp soil; no pigment

What is M. chelonei

Weakly gram +, similar to corynebacterium species; cutaneous infections

What is M. leprae

Strongly acid fast, ONLY GROWS IN MOUSE FOOT PADS; CANNOT BE CULTURED

What are the symptoms that can indicated leprosy

Diagnosis needs only 2/3 or ½ of symptoms: Lesion, loss of sensitivity, nerve enlarging, positive AFB (by split skin smear)

What is the spread of M leprae

Spread by droplet, direct skin, breast milk, insect bites

how does M leprae cause skin damage

Direct contact with bacterium or CMI attack on nerves

What is tuberculoid (paucibacillary) leprosy

Very AFB, nerve damage caused by CMIR, positive lepromin skin test, granulomas

What is lepromatous (multibacillary) leprosy

Poor CMIR, negative lepromin skin test; leonine facies and ENL development

What is the pathogenesis of M. leprae

Through respiratory tract → Bacilli multiply in Schwann cells → Good or bad response → Disability/deformity

What is paucibacillary leprosy

1-5 skin lesions

What is multibacillary leprosy

6+ skin lesions

Treatment for leprosy

Dapsone

What is characteristic of actinomyces

Form long branching filaments, weakly AFB

What is actinomyces spp

Causes actinomycosis; anaerobe part of NF in oral cavity, catalase negative

What are the clinical findings of A israelii

Lesion is hard non tender that slowly drains pus through sinus tract; hard sulfur granules in pus; face and neck lesions; not communicable

What are the 5 major forms of A. isaraelii

Local: Cerivicofacial, abdominal; Implantation: mycetoma; inhalation: thoracic; disseminated disease

What characteristic of nocardia spp

Causes nocardiosis; inhibit phagosome-lysosome function; gram + and weakly AFB; uses MODIFIED acid fast

What are the cutaneous infections of nocardia spp

Mycetoma (abscess in sinus tract with sulfur granules); lymphocutaneous infection; superficial cellulitis and potential systemic spread

What is nocardia spp

AEROBES, found in soil; weakly AFB by modified Kinyoun; thin branching filaments

What is the clinical signs of pulmonary nocardia infection

Inhalation; similar to TB; productive cough, shortness of breath, chest pain, hemoptysis, fever, night sweat, weight loss and progressive fatigue

What is the clinical signs of brain abscess in nocardia infection

Most common extrapulmonary infection location; headache, nausea, vomiting, seizures or altered mental status

What is cutaneous nocardiosis

Cause primary cutaneous infection; cellulitis, skin abscess, nodule, ulcer; mycetoma

What is N. asteroids

Has a wet soil odor; gram + branching filamentous rod

What is N. brasiliensis

Common in southeast US; diff from N asteroides by hydrolysis of casein tyrosine and gelatin