Fastidious Bacteria
Terms
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What is the smallest of the small bacteria?
What is their distinguishing feature? -
Mycoplasma
Identifier: lack a cell wall -
What growth conditions are necessary for mycoplasma?
-Media
-Incubation -
Media must contain:
-serum (for protein)
-yeast
Incubation:
-Increased CO2
-Up to 1 month - How is mycoplasma identified?
-
Stereomicroscope -> fried egg morphology of tiny colonies.
DIENES STAIN -> short blue bacilli (GS does not work)
-Immunologic ID is best. - most pathogenic member of mycoplasma:
- Mycoplasma pneumoniae
-
What disease does M. pneumoniae cause?
What antibiotic treats this?
Treatment? -
-Walking pneumonia in young adults
-Erythromycin - What are 3 methods for detecting M. pneumoniae?
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1. EIA
2. Cold agglutinins (50%)
3. Nucleic acid probe I.D. - what are 4 species of mycoplasma other than pneumoniae?
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M. hominis
M. genitalium
M. fermentens
M. salivarium - What species of Mycoplasma are genital pathogens?
-
M. hominis
M. genitalium - Where is M. fermentens found?
- Vagina
- Where is M. salivarium normal flora?
- In the oral cavity.
- name of genital tract pathogen related to mycoplasma:
- ureaplasma urealyticum
- Essence of L-forms
-
lack a cell wall but due to a condition that caused it:
1. high conc. of penicillin
2. high conc. of salt -
type of bacteria that easily becomes
L-form:
what does it cause? -
Streptobacillus moniliformis
causes rat bite fever -
How many types of legionella are there?
Most common?
Commonly found in: -
about 40 species
L. pneumophila
Water - What does legionella pneumophila mean?
- Little legions of lung-loving bacteria
- What disease is caused by l. pneumophila?
- severe Acute Respiratory disease
-
How is L. pneumoniphila transmitted?
Who is it most commonly seen in? -
Inhalation/aspiration of H2O
Middle aged men - they smoke - Why was L. pneumophila hard to find?
- It doesn't stain! they could never find it in all those samples
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How does a L. pneumophila infection progress re: sx?
What is it treated with? -
-Starts w/ flu-like symptoms, high fever develops, then into
Lobar pneumonia w much sputum.
-Treat with erythromycin
Erythromcyin - What is Pontiac fever?
- A milder form of Legionnaire's disease caused by an antigenic variant.
- what specimen is tested for L. pneumophila?
- sputum; can be hard to get, so induce it.
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-What growth factor is needed for culturing Legionella?
-What agar is used? -
-L-cysteine.
-Agar: BCYE - buffered charcoal yeast extract media - what are the cultural (growth) characteristics of L. pneumophila?
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1st inoculate the plain BCYE: shouldn't see growth. Allows presumptive I.D.
2nd inoculate BCYE + cystine; then should see growth.
Growth requires 3-4 days and results in ground glass appearance of colonies - Name 3 methods for ID of Legionella:
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1. Growth on BCYE+cystine
2. Flourescent Ab Test
a. Direct (specimen/culture)
b. Indirect (serum - both conval. and acute phase)
3. Nucleic acid probes - PCR -
Legionella is
Catalase:
Oxidase; -
Cat +
Oxi weakly + - chemical component that causes Acid fastness:
- mycolic acid
- What genus is acid fast bacilli?
- Mycobacterium
- What 5 types of specimens can be tested for mycobacterium?
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1. Sputum, bronchoalveolar lavage, bronchial washings.
2. Gastric secretions (neutralize imm.)
3. Urine
4. Tissue, CSF, Blood
5. Skin
First morning specimens always - what are the OSHA requirements for mycobacterium processing
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1. neg air flow room -
biosafety level 3 room
2. Biolog. safety cabinet
3. Wear gowns, gloves, respirators
4. Skin test personnel ev. 6 months - whats the most important, first test you must do when testing for mycobacterium?
- DIRECT SMEAR - growth takes so long, this is the best way for fast info.
- what are 2 types of direct smears you can do for mycobacterium:
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-Acid fast: Kinyoun or Ziehl-neelson; must examine at least 15 min or 300 fields; easy to miss the bug on a TB smear.
-Flourescent: easier, but background/garbage also messes up - How to process a gastric or sputum culture for mycobacterium:
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1. NALC NAOH - digest mucous, decontaminate specimen, get rid of normal oral flora.
or
2. Trisodium phosphate + benzalkonium chloride; but #1 is better - How to process a urine specimen for mycobacterium:
- concentrate it by centrifugin
- What media is used for isolating Mycobacterium?
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-Lowenstein Jensen
-Middlebrook
-Broth AND Agar, can add antibiotics. -
What incubation conditions apply to Mycobacterium cult?
(skin, other)(temp and time) -
Skin: 30 C
All else: 37 C
Increased CO2
at least 8 weeks before calling neg! - What 3 things should be done if specimen with suspected mycobacterium grows?
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1. Check for acid fastness
2. check colony morph; if unpigment, expose to light, reincubate.
3. record time required for growth