Microscopic Morphology MBLB4500 Flashcards
(110 cards)
1
Q
Streptococcus pyogenes
A
Gram-positive cocci in chains Group A Beta-hemolytic (SBA) Catalase - Bacitracin sensitive (.04 units) Latex agglutination PYR’ase + (pyroglutamyl aminopeptidase)
Virulence factors
- M protein
- Hyaluronidase
- Streptokinase
- Streptolysin O
Infections
- Pharyngitis, tonsillitis
- Otitis media
- Scarlet fever
- Impetigo
- Cellulitis
Post-streptococcal sequelae
- Rheumatic fever
- Acute glomerulonephritis
2
Q
Streptococcus agalactiae
A
Gram-positive cocci in chains Group B Beta-hemolytic (weakly) Catalase - CAMP test + Bacitracin resistant Hippurate hydrolysis + Latex agglutination
Virulence factors
- Produces polysaccharide capsules
- 5 major antigen types
Infections
- Colonizer of female genital tract (10-30%)
- Leading cause of meningitis, septicemia, pneumonia in neonate
(a) Mortality rate 10-15%
(b) Recommendation is to screen all women in 3rd trimester - Urinary tract infections and bacteremia in elderly and immunocompromised 4. Post-surgical gynecologic infection
3
Q
Streptococcus bovis
A
Gram-positive cocci
alpha hemolytic/nonhemalytic
Group D
Members of the former “S. bovis group” which are infectious for humans include S. gallolyticus and S. infantarius.
Catalase negative Bile
esculin positive
6.5% NaCl negative (no growth)
Infections - associated with colon cancer and other GI diseases
4
Q
Streptococcus pneumoniae
A
Gram-positive diplocci (elongated in shape/Lancet-shaped)
Alpha hemolytic
Catalase -
Optochin susceptible
Bile soluble
Capsule polysaccharide typing (Quellung reaction)
Virulence factors
1. Polysaccharide capsule prevents phagocytosis
2. Pneumolysin that is toxic to pulmonary endothelial cells and may allow spread to
bloodstream
Infections- virulent strains are encapsulated
- Most frequent cause of otitis media in children -Community acquired bacterial pneumonia
- Meningitis
- Sinusitis
Can be normal flora of upper respiratory tract
5
Q
Enterococcus fecalis
A
Gram-positive cocci Group D Weakly alpha or non-hemolytic (usually) Catalase negative (or weakly positive) Bile esculin positive Grows in 6.5% NaCl PYR positive
Infections
- Normal flora of intestinal tract
- UTI
- Endocarditis
- Wound infections
6
Q
Enterococcus faecium
A
Gram-positive cocci Group D Weakly alpha or non-hemolytic (usually) Catalase negative (or weakly positive) Bile esculin positive Grows in 6.5% NaCl PYR positive
Infections
- Normal flora of intestinal tract
- UTI
- Endocarditis
- Wound infections
7
Q
Staphylococcus aureus
A
Gram-positive cocci in clusters
Catalase positive
Coagulase positive
Facultative anaerobe
Non-motile
Non-spore forming
Tolerates increased salt concentrations
Beta-hemolytic (golden pigment on sheep)
Mannitol fermentation (yellow colonies on MSA)
Found on the skin, in the nose, axillae and groin.
Survives for long periods in the environment.
Virulence Factors
- Coagulase
- Leukocidin
- Entertoxins (6 types)
- Lipases
- Hyaluronidase
- Protein A
- Hemolysins
- Skin Infections -
a. Pimples, folliculitis, impetigo, furuncles or boils, carbuncles, abscesses (referred to as pyoderma)
b. Scalded skin syndrome - Food Poisoning
- Toxic Shock Syndrome
- Pneumonia
- Osteomyelitis
- Gastroenteritis
8
Q
Staphylococcus epidermidis
A
Gram-positive cocci in clusters Catalase positive Coagulase negative Facultative anaerobe Non-motile Non-spore forming No Mannitol fermentation Tolerates increased salt concentrations
Inhabits skin of most people and is of low virulence.
Diseases
- Endocarditis - heart valves infected
- Prosthetic infections - slime layer of organism inhibits phagocytosis 3. IV site infections - sepsis
9
Q
Staphylococcus saprophyticus
A
Gram-positive cocci in clusters Catalase positive Coagulase negative Facultative anaerobe Non-motile Non-spore forming Tolerates increased salt concentrations Resistant to novobiocin
A. Associated with urinary tract infections in young, sexually active women
B. Unique binding property to epithelium of urethra or bladder
9
Q
Peptostreptococcus sp.
A
Gram-positive cocci
10
Q
Micrococcus sp.
A
Gram-positive cocci Aerobic Catalase + Coagulase - Fermentation of glucose anaerobically - Bacitracin (.04 units) susceptibility: S Furozolidone (100 μg) susceptibility: R Normal flora on skin and in mucous membranes; found in soil and water
Identification: on sheep blood agar, colonies are slow growers (48 hrs) and are often yellow pigmented.

Infection: Rare cause of endocarditis
12
Q
Neisseria meningitidis
A
Gram-negative cocci (diplococci; kidney shaped)
Catalase +
Oxidase +
Pili: aid attachment of bacteria to human cells
Aerobic
Capnophilic
Optimal growth at 35-37°C in moist environment
Nonmotile
Non-spore-former
Affinity for mucous membranes
FASTIDIOUS (sensitive to drying and temperature; survives poorly in environment)
Capsules present
Normal nasopharyngeal flora (10%) only reservoir.
13
Q
Neisseria gonorrhoeae
A
Gram-negative cocci (diplococci; kidney shaped)
Catalase +
Oxidase +
Pili: aid attachment of bacteria to human cells
Aerobic
Capnophilic
Optimal growth at 35-37°C in moist environment
Nonmotile
Non-spore-former
Affinity for mucous membranes
FASTIDIOUS (sensitive to drying and temperature; survives poorly in environment)
More fastidious than N. meningitidis
Not encapsulated
13
Q
Veillonella sp.
A
Gram-negative cocci
14
Q
Moraxella catarrhalis
A
Gram-negative cocci Normal flora of upper respiratory tract Not fastidious as N. gonorrhoeae and N. meningitidis (a) grows well on sheep blood agar (b) not sensitive to drying or temperature (c) “push” positive 4. Oxidase + 5. CTA sugars negative
Infections
- otitis media
- sinusitis
- In immunocompromised and elderly
(a) pneumonia
(b) bronchitis
16
Q
Listeria monocytogenes
A
Gram-positive rod
Non-spore-former
- Facultative anaerobe
- Beta hemolysis on Sheep Blood Agar
(zone is narrow and colony looks like Strep agalactiae) - Catalase +
- Bile esculin +
- Tumbling motility at 25° C
- Cold enrichment - the organism grows well at 4°C
In humans, significant infections in neonates, pregnant women, and immunocompromised persons
17
Q
Corynebacterium sp. (“diphtheroids”)
A
Gram-positive bacilli- pleomorphic rods that palisade or resemble “Chinese characters”
Non-spore-former
Most are catalase +
18
Q
Corynebacterium diphtheria
A
Gram-positive bacilli Non-spore-former -Methylene blue stain - shows metachromatic granules -Media/isolation: 1. Loeffler agar slant 2. Sheep blood agar 3. Tellurite or Tinsdale -Toxin production using an Elek plate - this is to determine if the isolate produces diphtheria toxin. Infection – diphtheria
19
Q
Corynebacterium jeikeium
A
Gram-positive bacilli
Non-spore-former
1. Normal flora of skin
2. Causes infection mostly in immunocompromised
(a). prosthetic heart valve (b). septicemia
(c). skin infections
3. Often resistant to multiple antibiotics
20
Q
Nocardia asteroides
A
Gram-positive bacilli (branching)
Non-spore-former
1. Produces aerial hyphae
2. Always considered a pathogen; pulmonary infections, brain abscesses
3. Colonies are heaped and folded and are often orange or salmon in color
4. Partially acid-fast using the modified Kinyoun stain
20
Q
Erysipelothrix rhusiopathiae
A
Gram-positive rod
22
Q
Erysipelothrix rhusiopathiae
A
Gram-positive bacilli
Non-spore-former
- One species only
- Facultative anaerobe
- Catalase negative
- Non-motile
- Grows in 8.5% NaCl
- Grows well on SBA, CNA, and Chocolate
- Produces hydrogen sulfide on Triple Sugar Iron
- Disease in humans associated with animals
- Localized infection on skin, particularly fingers and hands
23
Q
Bacillus sp.
A
Gram-positive bacilli (large, box car shaped rods that may stain gram variable)
Spore-former
- Generally considered low virulence saprophytes found in the soil, water, dust, and animal products.
- Common contaminants in the laboratory.
- Aerobic or facultative anaerobe
- Catalase +
24
Q
Bacillus anthracis
A
Gram-positive bacilli
Spore-former
Causes the infection called anthrax. It is the most virulent human pathogen of the Bacillus species.
a. Animals
b. Humans
- Cutaneous, Pulmonary, GI
25
Bacillus cereus
Gram-positive bacilli
Spore-former
1. Causes food poisoning associated with rice, and eye and wound infections
26
Bacillus subtilus
Gram-positive bacilli
Spore-former
1. Laboratory contaminant
27
Clostridium perfringens
Gram-positive bacilli (large box car shaped rods)
Spore-former
Anaerobes
Catalase negative (usually)
a. Produces many exotoxins and enzymes that divide the organism into 7 types (A-G), with type A being the most important to humans.
b. Beta-hemolytic on sheep blood agar (double zone hemolysis)
c. Rapid Growth
d. Produces high amounts of gas
e. Lecithinase positive on egg yolk agar
Infection: Gas gangrene (Gas is produced when the muscle carbohydrates are fermented by the organisms.)
Food poisoning.
28
Clostridium tetani
Gram-positive bacilli
Spore-former
Anaerobes
Catalase negative (usually)
a. Ubiquitous in soil, dust, human and animal excreta.
b. Spores enter the body through wounds, then germinate to vegetative cells. c. Toxin is produced if conditions are right. The toxin goes to the CNS
via the blood stream or lymph nodes and neurally through the tissues.
Infection: Tetanus (Tetanus toxin blocks the relaxation, so both sets of muscle contract.)
29
Clostridium botulinum
Gram-positive bacilli (large rods)
Spore-former
Anaerobes
Catalase negative (usually)
a. spores in soil, water, and on surface of fresh vegetables.
Infections: Food botulism (The organism multiplies in storage and releases the toxin. The toxin is inactivated by sufficient cooking - heat 1000C for 10 min.) Wound botulism.
Toxin: acts on the peripheral nervous system blocking muscle contraction, resulting in paralysis.
Treatment:
High doses horse antitoxin Supportive measures Penicillin
29
Actinomyces sp.
Gram-positive rod
30
Clostridium difficile
Gram-positive bacilli (large rods)
Spore-former
Anaerobes
Catalase negative (usually)
a. Present in the bowel of healthy persons or acquired from an exogenous source.
b. Antibiotic therapy alters the normal flora of the bowel and allows C. difficile to overgrow.
c. Produces toxins; bloody diarrhea is a result and may develop a pseudomembrane - Pseudomembraneous colitis
1. Identification is made by detecting the toxin in the stool b. CCFA agar (Cycloserine-Cefoxitin-egg Fructose agar)
- colonies are yellowish with ground glass appearance
- colonies smell like horse manure!
31
Propionibacterium acnes
Gram-positive rod
32
Mobiluncus sp.
Gram-positive rod
33
Escherichia coli
Gram-negative rod
-The major facultative anaerobe inhabitant of the large intestine
-The most commonly isolated opportunistic human pathogen causing urinary tract
and wound infections, pneumonia, meningitis and septicemia.
-Some serogroups and toxin-producing strains are highly virulent primary
pathogens.
-Primary cause of "Travelers' Diarrhea."
-There are at least 165 “O” antigens, 100 "K" antigens, and 50 "H" antigens
described for E. coli.
34
Escherichia coli
Gram-negative rod
-The major facultative anaerobe inhabitant of the large intestine
-The most commonly isolated opportunistic human pathogen causing urinary tract
and wound infections, pneumonia, meningitis and septicemia.
-Some serogroups and toxin-producing strains are highly virulent primary
pathogens.
-Produces heat-stable and a heat-labile enterotoxin.
-Primary cause of "Travelers' Diarrhea."
-There are at least 165 “O” antigens, 100 "K" antigens, and 50 "H" antigens
described for E. coli.
35
Klebsiella oxytoca
Gram-negative rod
36
Enterobacter cloacae
Gram-negative rod
37
Citrobacter freundii
Gram-negative rod
38
Citrobacter diversus
Gram-negative rod
39
Edwardsella tarda
Gram-negative rod
40
Serratia marcescens
Gram-negative rod
41
Proteus mirabilis
Gram-negative rod
42
Proteus vulgaris
Gram-negative rod
43
Proteus penneri
Gram-negative rod
44
Morganella morganii
Gram-negative rod
45
Providencia stuartti
Gram-negative rod
46
Providencia rettgeri
Gram-negative rod
48
Salmonella sp.
```
Gram-negative rod
Non-spore-forming
Facultatively anaerobic
Ferment glucose
Reduce nitrates to nitrites
Does not produce cytochrome oxidase
Prone to a carrier state
```
48
Salmonella typhi
```
Gram-negative rod
Non-spore-forming
Facultatively anaerobic
Ferment glucose
Reduce nitrates to nitrites
Does not produce cytochrome oxidase
Prone to a carrier state
Infection: typhoid fever
```
49
Shigella dysenteriae
Gram-negative rod
-Produces a potent exotoxin or "shiga toxin" that causes hemorrhages leading to bloody diarrhea.
Infection: dysentery
51
Shigella flexneri
Gram-negative rod
| Infection: dysentery
52
Shigella boydii
Gram-negative rod
| Infection: dysentery
52
Yersenia pseudotuberculosis
Gram-negative rod
53
Shigella sonnei
Gram-negative rod
| Infection: dysentery
54
Yersenia enterocolitica
Gram-negative rod
Most commonly isolated Yersenia species.
Infection: Acute enteritis
The clinical manifestations include septicemia accompanied by mesenteric lymphadenitis (a presentation similar to appendicitis.)
55
Vibrio cholera
Gram-negative rod (CURVED)
56
Vibrio cholera
-Gram-negative rod (CURVED)
-Oxidase +
-Require NaCl for growth
-SBA - grows well on this media
-Nonlactose fermenter
-MacConkey - grows on this media.
-CBS(Thiosulfate Citrate Bile Salts Sucrose)-selects for Vibrio because of the high pH of 8.6, citrate salts, oxgall, and sodium cholate.
-Vibrio cholera ferments the sucrose and produces yellow colonies on TCBS
-0/129 sensitivity - this is a vibriostatic agent (2,4 diamino-6,7-diisopropyl- pteridine phosphate)
-Many V. cholera isolates from Bangledesh and surrounding area are
now resistant to 0/129
58
Vibrio parahemolyticus
- Gram-negative rod (CURVED)
- Oxidase +
- Require NaCl for growth
- SBA - grows well on this media
- Nonlactose fermenter
- MacConkey - grows on this media.
- CBS(Thiosulfate Citrate Bile Salts Sucrose)-selects for Vibrio because of the high pH of 8.6, citrate salts, oxgall, and sodium cholate.
- 0/129 sensitivity - this is a vibriostatic agent (2,4 diamino-6,7-diisopropyl- pteridine phosphate)
- causes acute gastroenteritis following ingestion of raw fish, oysters, shrimp, crab
- cause of 50-70% of foodborne diarrhea in Japan
- most frequent Vibrio sp. isolated in U.S.
59
Vibrio vulnificus
- Gram-negative rod (CURVED)
- Oxidase +
- Require NaCl for growth
- SBA - grows well on this media
- Nonlactose fermenter
- MacConkey - grows on this media.
- CBS(Thiosulfate Citrate Bile Salts Sucrose)-selects for Vibrio because of the high pH of 8.6, citrate salts, oxgall, and sodium cholate.
- 0/129 sensitivity - this is a vibriostatic agent (2,4 diamino-6,7-diisopropyl- pteridine phosphate)
- associated with oysters; very invasive and causes wound
infections and septicemia
- predisposing conditions are liver disease, high serum iron
60
Vibrio alginolyticus
- Gram-negative rod (CURVED)
- Oxidase +
- Require NaCl for growth
- SBA - grows well on this media
- Nonlactose fermenter
- MacConkey - grows on this media.
- CBS(Thiosulfate Citrate Bile Salts Sucrose)-selects for Vibrio because of the high pH of 8.6, citrate salts, oxgall, and sodium cholate.
- 0/129 sensitivity - this is a vibriostatic agent (2,4 diamino-6,7-diisopropyl- pteridine phosphate)
not common but causes wound, eye, and ear infections
61
Aeromonas hydrophila
Gram-negative rod
1. predominantly in fresh water, but also in brackish water or water with low saline
2. isolated from amphibians, reptiles, fish
3. many species associated with human infections are in fresh produce, beef,
poultry, pork, and dairy products
4. associated with diarrhea and also wounds
5. acquired near or in water
6. MacConkey agar - grows as a lactose or non-lactose fermenter fermenter
7. TCBS agar - NO GROWTH
8. OXIDASE POSITIVE
9. NaCl - not required
10. 0/129 - resistant
62
Plesiomonas shigelloides
Gram-negative rod
1. found in seawater and freshwater
2. associated with eating raw shellfish
3. rare cause of diarrhea
4. MacConkey agar - grows and may or may not ferment lactose
5. TCBS - NO GROWTH
6. OXIDASE POSITIVE
7. NaCl - not required
8. 0/129 - sensitive
(now classified as an enteric based on 16SrRNA sequencing)
63
Campylobacter jejuni
Gram-negative rod (CURVED)
- Formerly called Vibrio
- Inhabits GI tracts of animals – poultry, cattle, sheep, pigs, domestic pets
- Transmission to man occurs through contaminated water, poorly cooked meat or dairy products
- Most common agent of bacterial gastroenteritis in the US
Identification –
1. Isolation media
a. Campy-BAP - brucella agar with 10% sheep red blood cells, vancomycin, trimethoprim, cephalosporin, polymixin, and Amphotercin B
b. Campy Thio Broth - has same antibacterial and antifungal agents as blood agar plate (Campy-BAP)
2. Incubate at 42°C in 10% CO2
3. Wet mount – darting motility (?)
4. OXIDASE POSITIVE
5. Hippurate hydrolysis positive
64
Helicobacter pylori
Gram-negative rod (CURVED)
A. Causative agent of peptic ulcer disease and major risk factor for gastric cancer
B. Formerly considered a Campylobacter
C. Identification – gastric biopsy specimens are recommended
1.. Difficult to culture - Brain heart infusion agar with horse blood, Brucella agar with horse blood, or Skirrows Pylori agar
2. 5-12% CO2 at 37°C, but needs 5-7days to grow
3. Detection of H. pylori antigen or antibodies in stool specimens
4. Urea Breath Test
5. Endoscopy
65
Pseudomonas aeruginosa
Gram-negative rod (Slender)
- Aerobic
- Non-spore-forming
- Non-fermenter
- Oxidase Positive
- β-hemolytic; produce "green metallic sheen" and fruity odor on sheep blood agar.
- Oxidize glucose
- Grow on MacConkey Agar
- Motile by polar monotrichous flagella
- Produces a diffusable fluorescent pigment (pyocyanin)
- Grow at 42 C
66
Acinetobacter baumanii
```
Gram-negative rod
-Aerobic
-Non-spore-forming
-Non-fermenter
-Oxidase negative
-Oxidize maltose
-Oxidize glucose
-Nonmotile
-Grow on MacConkey where their very strong oxidation can make the colonies appear
purple.
```
67
Stenotrophomonas maltophilia
Gram-negative rod (short to medium length)
-Aerobic
-Non-spore-forming
-Non-fermenter
-Slowly oxidize glucose, often more rapidly break down maltose
-Oxidase Negative
-Grow on MacConkey Agar
-Colonies on sheep blood agar can appear greenish, but negative oxidase distinguishes
from Pseudomonas
-Motile - polar tuft of three or more flagella
68
Burkholderia cepacia
Gram-negative rod (straight to slightly curved)
Aerobic
Non-spore-forming
Non-fermenter
-Oxidizes glucose
-Oxidase positive ...or weakly positive or negative
-Grows on MacConkey, but growth on MacConkey OR Sheep Blood may be delayed because the organism prefers lower temperatures (30°C)
-Motile - polar tuft of three or more flagella
-Odor - can have a distinctive odor (like a potato cellar or a freshly opened sack of
potatoes) when grown on Sheep blood agar. (This particularly odorous strain is common among CF patients in Utah.)
-Was first described as an opportunistic pathogen in cystic fibrosis patients
in 1972.
68
Flavobacterium sp.
Gram-negative rod
69
Chryseobacterium menigosepticum
```
Gram-negative rod (slightly pleomorphic)
Aerobic
Non-spore-forming
Non-fermenter
Nonmotile
Oxidase positive
Actually weakly ferment glucose, but usually give initial K/K reaction on TSI
Usually grow on MacConkey Agar (may not)
Yellow pigment is hallmark of the genus
```
71
Hemophilus influenzae
Gram-negative rod (Pleomorphic)
- FASTIDIOUS
- Requires both X (Hemin) and V (NAD) factor for growth
- Negative for porphyrin
Chocolate agar - both X and V factors are available
Sheep blood agar - only X factor is available, but Haemophilus may be seen
“satelliting” around other organisms that are releasing NAD.
-Requires 3-5% CO2 for growth
72
Hemophilus parainfluenzae
Gram-negative rod (Pleomorphic)
- FASTIDIOUS
- Requires X factor or V factor for growth
- Requires 3-5% CO2 for growth
- Normal flora of the upper respiratory tract
- Accounts for 75% of Hemophilus flora in oral cavity and pharynx
Infection: Endocarditis (rare)
73
Hemophilus ducreyi
Gram-negative rod (Pleomorphic)
- FASTIDIOUS
- Requires X factor or V factor for growth
- Requires 3-5% CO2 for growth
Infection: venereal disease soft chancre or chancroid, with an ulcer on the genitals
74
Bordetella pertussis
Gram-negative rod (small) or coccobacillus
- Strict aerobe
- Affinity for epithelial cells of nasopharynx and elaborates an exotoxin.
- Transmitted via respiratory droplets
- Colonizes the mucous membranes of the respiratory tract
Infection: Whopping cough
75
Legionella pneumophila
Gram-negative rod (thin)
Culture Requirements
1. Buffered Charcoal Yeast Extract agar (BCYE)
2. Incubate at 35°C in a moist environment with or without 2-5% CO2 for
minimum of 5 days
Infection: Legionnaires Disease
76
Brucella sp.
Gram-negative coccobacillus (small)
- Intracellular parasite, being ingested by circulating monocytes
- Transmitted by ingestion of raw milk, direct contact, inhalation
- Zoonoses
Infection: Undulant Fever
Symptoms are chills, fever, sweating weakness, and fatigue, weight loss
77
Franciscella tularensis
Gram-negative coccobacillus (tiny, with with bipolar staining)
-Strict aerobe
-sero-agglutination for rapid identification (b/c organism is difficult to grow)
Infection: Tularemia
1. Acute, febrile disease characterized by rapid onset and flu-like symptoms
2. Fever, chills, headache, and myalgia, lymph node swelling, and an ulcer
at the site of inoculation
77
Bacteroides sp.
Gram-negative rod
78
Pasturella multocida
Gram-negative pleomorphic coccobacillus
-Oxidase +
-Indole +
-Grows well on sheep blood and chocolate but NO GROWTH on MacConkey
-Looks and smells like Haemophilus, but grows on SBA
-Associated with animals. Normal flora in respiratory tract of cats, dogs, rabbits,
panthers, etc.
-It is common pathogen in dog and cat bites or scratches, and cellulitis develops
-Dangerous affinity for bones and joints.
79
Bacteroides fragilis
Gram-negative rod
80
Fusobacterium sp.
Gram-negative rod
81
Prevotella sp.
Gram-negative rod
82
Porphyromonas sp.
Gram-negative rod
83
Mycobacterium tuberculosis
Acid fast bacteria (Gram stain poorly)
84
Mycobacterium bovis
Acid fast bacteria (Gram stain poorly)
85
Mycobacterium leprae
Acid fast bacteria (Gram stain poorly)
86
Mycobacterium avium-intracellulare
Acid fast bacteria (Gram stain poorly)
87
Mycobacterium marinum
Acid fast bacteria (Gram stain poorly)
88
Mycobacterium gordonae
Acid fast bacteria (Gram stain poorly)
89
Mycoplasma pneumoniae
NO cell wall; will NOT Gram stain
90
Mycoplasma hominis
NO cell wall; will NOT Gram stain
91
Ureaplasma urealyticum
NO cell wall; will NOT Gram stain
92
Chlamydia psittaci
Gram-negative like cell wall, but obligately intracellular; not likely to Gram stain
93
Chlamydia trachomatis
Gram-negative like cell wall, but obligately intracellular; not likely to Gram stain
Causative agent of Chlamydia
94
Coxiella burnetti
Gram-negative like cell wall, but obligately intracellular; not likely to Gram stain
95
Rickettsia rickettsii
Gram-negative like cell wall, but obligately intracellular; not likely to Gram stain
Causative agent of Rocky Mountain spotted fever
Tick vector
96
Rickettsia typhi
Gram-negative like cell wall, but obligately intracellular; not likely to Gram stain
97
Treponema pallidum
Spirochete (Gram-negative, but often stain poorly: best visualized with dark-field illumination)
Causative agent of Syphilis
98
Borrelia recurrentis
Spirochete (Gram-negative, but often stain poorly: best visualized with dark-field illumination)
99
Borrelia burgdorferi
Spirochete (Gram-negative, but often stain poorly: best visualized with dark-field illumination)
Causative agent of Lyme Disease (named for Old Lyme Connecticut)
100
Leptospira sp.
Spirochete (Gram-negative, but often stain poorly: best visualized with dark-field illumination)
101
Lactobacillus sp.
Gram positive bacilli (long and slender)
Non-spore-former
1. Normal flora of lower GI and genital tract
2. Bacterial vaginosis associated with decrease/absence of lactobacilli
- lowers pH of vaginal tract, helps control growth of other organisms.
102
Clostridium sp.
Gram positive bacilli (large rods/ Gram variable)
Spore former
Anaerobes
Catalase negative (usually)
-Inhabit soil, water, vegetation, large bowel of humans and other animals. Many are significant pathogens of livestock and wildlife.
103
Staphylococcus sp.
1. Normal flora of skin, mucous membranes, feces
2. 39 species (Manual of Clin Micro, 10th Ed)
3. Facultative anaerobe
4. Tolerates increased salt concentrations
5. Catalase positive
6. Non-motile
7. Non-spore forming
Identification of Staphylococcus
A. Gram stain - gram positive cocci in clusters B. Media and Appearance
1. Sheep blood agar – creamy white colonies
2. Mannitol salt agar - has 7.5% NaCl; all Staph will grow on this media. If the Staph species can ferment mannitol, the organism will grow as yellow colonies on this agar
104
Staphylococcus lugdunensis
```
Gram-positive cocci in clusters
Catalase positive
Coagulase negative
Facultative anaerobe
Non-motile
Non-spore forming
Tolerates increased salt concentrations
```
A. Native valve endocarditis
B. Foreign-body related skin infections that resemble S. aureus infections
105
Viridans Streptococcus
Primarily a descriptive term meaning “green” or alpha-hemolytic, sometimes non-hemolytic
Infections
1. Predominant organisms of normal upper respiratory flora
2. Most common cause of subacute bacterial endocarditis
Biochemical testing of viridans Streptococcus species
- Rule out S. pneumoniae, S. bovis, and Enterococcus
- Some species associated with brain and lung abscess formation, but species
identification is not usually necessary.
106
Haemophilus influenzae biogroup aegyptius
Gram-negative rod (Pleomorphic)
-FASTIDIOUS
-Requires X factor or V factor for growth
-Requires 3-5% CO2 for growth
Infection: pink eye (purulent and contagious)
107
Brucella abortus
Gram-negative coccobacilli (small)
- Intracellular parasite, being ingested by circulating monocytes
- Transmitted by ingestion of raw milk, direct contact, inhalation
- Zoonoses
- Natural habitat in cattle (also in buffalo, horses, camels, and yaks)
Infection: Undulant Fever
Symptoms are chills, fever, sweating weakness, and fatigue, weight loss
108
Brucella melitensis
Gram-negative coccobacilli (small)
- Intracellular parasite, being ingested by circulating monocytes
- Transmitted by ingestion of raw milk, direct contact, inhalation
- Zoonoses
- Goats, sheep (also camels and alpacas, and cattle is some areas)
Infection: Undulant Fever
Symptoms are chills, fever, sweating weakness, and fatigue, weight loss
109
Brucella suis
Gram-negative coccobacilli (small)
- Intracellular parasite, being ingested by circulating monocytes
- Transmitted by ingestion of raw milk, direct contact, inhalation
- Zoonoses
- Pigs (also reindeer and caribou)
Infection: Undulant Fever
Symptoms are chills, fever, sweating weakness, and fatigue, weight loss
