Gram Negative Bacilli
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| N. gonorrhoeae gram stain morphology | Gram negative diplococcus and appears intracellular in neutrophils
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| Gonorrhoeae is positive with: | Oxidase, catalase, glucose
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| Growth environment for N. gonorrhoeae | 5-10% CO2 at 35 degrees C
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| How is gonorrhoeae diagnosed in women? | Gram stain --> diplococcus from culture
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| Virulence factors of N. gonorrhoeae | Pili,
Adhesion factors
IgA protease
Capsule - escapes phagocytosis
Higher risk for patients with complement deficiencies
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| What N. gonorrhoeae causes: | Most common agent of septic arthritis in adults younger than 30
infections of the urethra, endocervix, anal canal, pharynx, and conjunctiva
Second most reported STD
Major cause of venereal disease
Possibly mixed with chlamydia
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| Gonorrhea in males | 2-7 days on incubation.
Discharge, Dysuria, prostatis, epididymitis
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| Gonorrhea in females | Urethral infections and cervicitis
produce cervical discharge, fever, acute pain and dysuria
cause pelvic inflammatory disease (PID), gonococcal arthritis, endometritis and peritonitis.
PID may cause sterility
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| Gonorrhea treatment | most are positive for beta-lactamase production
Treat with: Ceftriaxone
susceptibility testing for quinolone
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| What is PPNG? | Penicillinase positive Neisseria gonorrhoeae
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| Treatment for Gonorrhea with concurrent Chlamydia? | 7 day regimen of doxycycline
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| Gonococcal Ophthalmia Neonatorum | severe conjunctivitis in neonates leading to blindness
Infected by vaginal delivery
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| Treatment/prevention for Gonococcal Ophthalmia Neonatorum | antimicrobial eye drops are instilled within 1 hour of delivery
Or treat with 1% tetracycline eye ointment or 0.5% erythromycin eye ointment
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| Neisseria meningitidis is positive for: | Maltose, oxidase, and glucose
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| Neisseria meningitidis colony morphology: | flat, smooth, gray to white on chocolate
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| Virulence factors of Neisseria meningitidis | antiphagocytic capsule.
Cell wall endotoxin --> septic shock
Pili
IgA protease
Capsule - antiphagocytic and determines is serogroup: A, B, C, Y, and W135
Higher risk for patients with complement deficiencies
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| Specimens for Neisseria meningitidis | CSF, sputum, blood, nasopharyngeal swabs
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| Natural habitat and transmission of Neisseria meningitidis | nasopharyngeal tract in humans.
Transmission through droplets and close contact
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| Treatment for Neisseria meningitidis | Broad-spectrum cephalosporin
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| Two peak ages for Neisseria meningitidis infection? | babies 3-9 months old (immune system not fully developed)
Teens in crowded conditions (dorms)
Highest virulence is during winter.
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| Neisseria meningitidis pathogenesis | engulfed by epithelial cells and survive and multiply in the bloodstream
Once bacteria reaches the subarachnoid space- proliferation is uncontrolled.
Survivors can suffer from neurological sequelae
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| Complications of Neisseria meningitidis? | DIC
Thrombocytopenia
Petechiae
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| Treatment for meningococcal meningitis? | Rifampin and Ciprofloxacin
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| Vaccine for Neisseria meningitidis? | polysaccharide capsular antigens for groups A,C,Y, and W135
Group B is a poor immunogen
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| What is a good ID test for Neisserria? | rapid carbohydrate utilization
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| what is the indictor in the rapid carbohydrate utilization test? | Phenol red
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| What sugars are tested for? | Glucose, fructose, maltose, lactose
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| Mycobacteria characteristics | non spore forming
nonmotile
obligate aerobes
environmental organisms
use glycerol as a carbon source
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| Mycobacteria cell wall structure | high lipid content - 60% mycolic acids
protects from dehydration, alkaline, germicides, alcohol acids
Hydrophobic
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| Glycoprotein found in mycobacteria | N-glycolymuramic acid
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| Mycobacteria with gram stain | poorly stained gram-positive bacilli
"gram ghosts"
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| Ziehl-Neelsen | Heat stain acid fast stain
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| Ziehl-Neelsen reagents | carbofuchsin, acid-alcohol (HCL), and methylene blue or malachite green
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| Difference between Ziehl-Neelsen and Kinyoun? | Doesn't use heat- replaces heat with Phenol
Same reagents
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| How many fields are needed to examine for an acid-fast smear? | 300 fields before reporting negative
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| Advantages of a Fluorochrome stain? | Can be examined at lower magnification
More sensitive than an acid-fast stain
more fields can be examined faster
can be re-stained using an acid-fast procedure
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| Reagents for Fluorochrome stain | auramine-rhodamine, acid-alcohol, and potassium permanganate
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| What does potassium permanganate do? | quenches and reduces the background fluorescence of cellular debris.
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| Lowenstein-Jensen agar - what's in it? | egg-based with malachite green to inhibit normal flora
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| Incubation of Lowenstein-jensen agar: | 5-10% CO2 at 35-37C for a week with loose caps and then 7 more weeks with tightened caps,
protect from the light
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| Middlebrook 7H10/7H11 media | agar based
contains 2% glycerol (support MAC growth)
must be refrigerated and incubated in the dark
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| What happens with 7H11 agar is exposed to light? | May release formaldehyde which is toxic to mycobacteria
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| Benefits of liquid AFB media? | provide more rapid recovery of AFB than solid medium
isolation rates are also higher
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| Mycobacterium growth index tube (MGIT) | contains 7H9 broth with larges amounts of O2 to quench the fluorescence of a fluorochrome
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| Incubation of mycobacteria? | 35C in the dark with 5-10% CO2 and high humidity.
cultures held for 8 weeks before negative
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| Incubation of M marinum, M ulcerans, and M haemophilum? | (skin lesions)
solid media at 25-30C
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| Semiquantitative catalase test: | All mycobacteria produce catalase
Strains of TB are <45mm of bubbles
Non-TB are >45mm of bubbles
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| Heat-sensitive catalase: | mycobacteria heated to 68C for 20 minutes with 30% H2O2 and 10% 80
TB strains are negative (no bubbles)
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| What does Niacin do? | plays an important role in the redox reactions that occur during mycobacterial metabolism
It accumulates in the medium in which the organisms grow
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| Niacin test | should be performed on cultures 3 weeks or older
if positive (yellow color) and colonies are buff color and rough - maybe M. TB
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| Nitrate test | M. TB and M. kansasii are positive
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| Arylsulfatase test | 3 day test
M. fortuitum and M. chelonae are positive
ability of enzyme to breakdown phenolphthalein disulfide into phenolphthalein
turn red in presence of sodium bicarbonate
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| Thiophene-2-Carboxylic Acid Hydrazide (TCH) | differ M. bovis (susceptible) from M. TB (resistant)
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| Tween 80 | nonpathogenic, slow growing scotochromogens and nonphotochromogens production a lipase that is able to hydrolyze to oleic acid and polyoxyethylated sorbitol
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| Use of nucleic acid assays? | ID by DNA sequencing
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| AccuProbe | for M. TB and M. avium species
highly specific
takes less than 2 hours
can use culture isolates
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| Direct nucleic acid amplification | Detects M. TB
target: 16srRNA gene
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| Mycobacterium tuberculosis complex | M.tuberculosis
M. Bovis
M. africanum
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| What does NTM or MOTT stand for? | Nontuberculuous mycobacteria
Mycobacteria other than M.TB
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| Characteristics of NTMs? | Slow growing
opprotunisitc infections in AIDS
Rapid growing
Noncultiviable: M. leprae
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| Tuberculosis | ancient disease
entered human population when cattle were domesticated
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| Transmission of Tuberculosis | Airborne: inhalation of tiny droplet - cause chronic lowe respiratory tract disease
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| TB suspect | Hemoptysis (coughing blood)
Persistent cough for 3 or more weeks
weight loss
fever
night sweats
collect 3 specimens
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| Where can bacteria of TB spread? | lymphatic system, CNS, and heart
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| What does TB do to macrophages? | form multinucleated cells and form granulomas with other cells --> tubercles
Lesions can calcify and make a ghon complex.
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| What causes a reactivation of TB? | alteration in the cell-mediated immune response
poor nutrient, alcoholism, diabetes,
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| First line drugs for TB? | Rifampin, isoniazid, pyrazinamide, ethambutol, streptomycin
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| Miliary tuberculosis | lungs look like they have millet seeds
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| M. TB definitive ID | colonies on LJ appear non pigmented, dry, and granular
roselike formation from broth culture on acid-fast stain
Niacin positive
Nitrate positive
68C catalase positive
NAP susceptible
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| Tests for TB | Skin test
purified protein derivative (PPD) test - antigen is composed of heat-killed, filtered, ammonium sulfate precipitated protein
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| PPD results | person who has been infected by TB will show erythema and induration firmness
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| QuantiFERON -TB gold test | measure cell-mediated immune response to M TB
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| Runyon Classification of NTM | Made in 1959
based on phenotypic characteristics - growth rate and colonial pigmentation
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| Photochromogens | colonies are pigmented when exposed to light.
Pigment is controlled by an O2-dependent light inducible enzyme
M. kansasii
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| Scotochromogens | colonies are pigmented weather grown in dark or light
M. scrogulaceum
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| Nonphotochromogens | No pigment
M. avium
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| Rapid growers | appear on media in <7days
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| M. bovis | zoonosis
pulmonary infections in cattle and humans
nonphotochromogen
TCH susceptible
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| M. avium complex | M.avium and M.intracellularae
from water, soil, and dairy products
affects immunocompromised
causes lymphadenitis in children
slow growing non-chromogen
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| M. kansasii | from tap water
pulmonary infections - resembles TB but cannot disseminate in healthy patients
most common slow growing photochromogen
Nitrate and Catalase positive
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| M.xenopi | from water - hot water taps
transmitted in aerosols
pulmonary infections in adults
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| M.ulcerans, M.marinum, and M.haemophilum | skin infections
grow on surface of extremities because optimal temperature 30-32
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| Causative agent of swimming pool granuloma? | M. marimum
develop granulomatous skin lesions
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| M.fortuitum, M.chelonae, M.abscessus | causes abscesses and osteomyelitis
weakly virulent
rapidly growing mycobacteria
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| M.gordonae | found in fresh and tap water
rarely pathogenic
slow growing scotochromogen
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| M.scrofulaceum | Causes cervical lymphadenitis mainly in children
slow growing scotochromogen
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| Diagnosis of leprosy | Hypopigmented skin lesion
skin-smar positive for acid-fast bacilli
OCR
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| Optimal temperature for M. leprae - leprosy | 33 C
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| Transmission of M. leprae | person to person through inhalation or contact with infected skin
Armadillos are carriers
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| Signs of leprosy | discolored light patches on skin and loss of feeling
affects nerves: numbness, paralyzed muscles
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| Treatment of Leprosy | rifampin, clofazimin, and dapsone
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| TB Specimen collection and transport | Urine: morning
sputum or bronchoscope aspirations
feces
10cc of CSF
blood
wounds, skin lesions
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| Transport medium for TB specimens? | Amies or Stuarts medium
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| N-acetyl-L-Cysteine (NALC) | mucolytic agent is used to digest mucus and free trapped mycobacteria.
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| Specimen treated with NaOH | increases the pH to a level that is antibacterial
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| What is resistance due to? | Non adherence
Incorrect drug prescription
Poor quality of drugs
erratic supply of drugs
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| Multidrug-resistant M.tuberculosis (MDR-TB) | Resistance to isoniazid and rifampin
poor prognosis
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| Extremely-drug resistant M.tuberculosis(XDR-TB) | Resistance to any fluoroquinolone
at least one of three injectable second-line drugs in addition to isoniazid and rifampin.
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| Vaccines for TB | Bacille Calmette-Guerin - BCG derived from M. bovis
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