Gram Negative Bacilli and coccobacilli mix

Question 1

Name 5 important gram-negative organisms that are not Enterobacterialis,coming from aquatic sources, and one related that is found in the human stomach

Answer 1

Vibrio, Aeromonas, Plesiomonas, Campylobacter, and Helicobacter (the last one)

Question 2

How does Aeromonas hydrophila appear on SBA and MAC?, and what is its oxidase and indole status?

Answer 2

Large, round raised and opaque with strong beta hemolysis; ferments lactose like E. coli; is OX POS and IND POS

Question 3

WHat distinguishes Aeromonads from Enteric bacteria especially if showing beta-hemolysis and lactose fermentation?

Answer 3

They are OX pos (enterics are NEG)

Question 4

On what medium will Aeromonas form pink-centered colonies from mannitol fermentation , resembling another enterobacteriaceae with a characteristic morphology?

Answer 4

CIN, on which Yersinia enterocolitisa (OX =) forms red bullsye, looking very similar

Question 5

What are the best tests to distinguish Aeromonas from Vibrios?

Answer 5

The string test (Vibrios positive usu) and O/129 susceptibility (most Vibrios S, Aeromonads R); Also, growth in NaCl: Aeros and Plesios grow well with 0%, but most Vibrios can’t grow without NaCl

*** NOTE that V. cholerae (and mimicus) is nonhalophiliic so this must be done in conjunction with string and O/129!!!!!

Question 6

Like Vibrios and Aeromonads, this organism is OX POS, glucose-fermenting, GNB with polar flagella, but it is now classed with the Enterobactericeae, and is the only OX positive of that group:

Answer 6

Plesiomonas shigelloides

Question 7

Where is Plesiomonas found, generally?

Answer 7

mainly in FRESH and ESTAURINE waters of sub- and tropical climates bc not highly salt tolerant; also widely distributed in animals both warm and cold-blooded

Question 8

IN addition to diarrheal disease, PLesiomonas can cause what kinds of disease?

Answer 8

infections due to animal handling, especially water animals; can lead to bacteremia or meningitis;

Question 9

Aeromonas spp mainly cause what disease type? What spp is mostly associated , and what spp with more serious complications such as HUS?

Answer 9

Diarrheal/enteric; A. caviae; A. hydrophila and A. veronii

Question 10

Between Aeromonas caviae and A. hydrophila, which is H2S and Glucose+gas positive?

Answer 10

A. hydrophila

Question 11

Many Vibrios grow on common SBAor CHOC; describe appearance and also on MAC

Answer 11

Medium to Large smooth opaque colonies, iridescent with greenish hue; most pathogenic Vibrios are NLFs on MAC, but some do, so always do oxidase…or sub any suspicious LFs to SBA for next day oxidase testing

Question 12

WHen might a selective media be warranted for possible Vibrio isolation and what media/how do certain spp appear?

Answer 12

If there is a possibilty due to seafood or seawater exposure or coastal travel; Use Thiosulfate Citrate Bile salt Sucrose, TCBS. Sucrose fermenters like V. cholerae will be yellow; non-sucrose fermenteres such as V. parahaemolyticus and most vulnificus will be green.

Question 13

Which Vibrios mainily cause: cholera (and how), and food poisoning?

Answer 13

Cholera: V. cholerae, by a toxin that stims CAMP in intestinal cells and causes extreme secretion of electrolytes, causing massive watery diarrhea, deadly.

V. parahaemolyticus more often causes food poisoning

Question 14

How are Vibrios different from Pseodomonads?

Answer 14

PSeudomonads don’t ferment any carbs, they are only oxidative (uncovered tube only metabolizes);

Question 15

How are Vibrios different from Plesiomonads?

Answer 15

Plesiomonas ferments inositol but deos not ferment mannitol, sucrose, or liquify gelatin; Vibrios DO NOT ferment inositol, and do mannitol, liquify gelatin, and usually sucrose

Question 16

this bacteria genus is associated with animal bite wounds and are gram-negative nonmotile, facultative anaerobic coccobacilli with better growth on CHOC; It requires cystine and is strictly aerobic….

Answer 16

Francisella tularensis: also it is oX and Urease negative; slow growth, may take 48 hours and need to check daily for 14 days; grows on CHOC but not blood

Question 17

what is the best combo for diagnosing Legionairre’s disease?

Answer 17

culture on BCYE and urine antigen detection

Question 18

describe staining of Legionella spp general characteristics and methods to enhance

Answer 18

they are weakly staining gram negative bacilli that can be both outside of and within macrophages/segs. Extending safranin time to 10 mins can help enhance stain

Question 19

How are Legionella with regards to culture requirements and oxygen

Answer 19

they are aerobic and require L-cysteine, do not grow on SBA and may grow on CHOC as tiny colonies but BCYE agar is used for best isolation

Question 20

describe the common colony morphology of Legionella and use of carbohydrate, catalase and oxidase characterisics

Answer 20

Young colonies have ground glass center with pink/lt blue/ or green bands on periphery; they are asaccharolytic and catalase & oxidase WEAKLY positive

Question 21

Legionella can be grouped by colors due to what phenomenon; what color is L. pneumophila known for?

Answer 21

Autofluorescence: yellow-green

Question 22

what are the two main clinical manifestations of infection with Legionella

Answer 22

febrile disease with pneumonia aka Legionarrie’s disease, and febrile disease without pulmonary involvement aka Pontiac fever.

Question 23

what are the two major media types useful for isolating Bordetella and what is the transport medium? what is common between?

Answer 23

Bordet-Gengou (potato infusion with glycerol and horse or sheep blood), and charcoal with horse blood and 40 mg/L cephalexin; Regan Lowe is like the charcoal media but with full agar strength.

*some B. pertussis strains are inhibited by this level of cephalexin so there should be a plate without it also cultured.

Question 24

How do colonies of Bordetella pertussis and parapertussis appear on Regan-Lowe or charcoal-horse blood, and on Bordet-gengou?

Answer 24

as smooth shiny mercury-droplet like on charcoal; As hemolytic on the potato agar

Question 25

Which Bordetella spp does not grow on blood agar, which do? which grows on MAC? which is oxidase neg?? Which are urease pos iin 24 hours and which in 4 hours, and which neg?

Answer 25

B. pertussis does not (usually) grow on BAP; , B. parapertussis grows on BAP and B. bronchiseptica grows on both BAP and MAC; All grow on the charcoal/ Regan-Lowe/Bordet-Gengou.

B. para is OX neg and produces urease in 24 hours; B. bronchiseptica is urease positive in 4 hours

Question 26

what is the classic disease name given to that caused by Bordetella pertussis? What is the vector?

Answer 26

Whooping cough. It is in human reservoirs exclusively, acquired by respiratory droplet or direct contact; there is a vaccine given in childhood, 5 dose.

Question 27

How are colonies suspicious for B. pertussis/parapertussis further evaluated?

Answer 27

direct fluorescent antigen staining (DFA), or agglutination (serological, both)

Question 28

What are the growth requirements for Campylobacter jejuni and what is an important biochemical test for confirmation? WHat is in the selective media at minimum?

Answer 28

It requires a microaerophilic and capnophilic environment (as does Helicobacter) at 42 C; Hippurate hydrolysis!!!! ( You used on your unknown)

A combo of antibiotics to eliminate normal colon bacteria: Vanco, TMP, Poly-B, AMpho-B (the PAV media they used….) plus 10% sheep blood

Question 29

WHat are common tests for detecting H. pylori infection?

Answer 29

rapid urease (2 hrs); the ureas breath test, fecal antigen detection, ( also tissue staining with microscopy, PCR….less common)

Question 30

describe the typical Campylobacter jejuni gram stain morphology

Answer 30

corkscrew or gull wing/ S-shape GNB, poor staining but enhanced with longer counterstain or use of carbolfuschin; on hanging drop have darting motility if in tryptic soy or brucella broth

Question 31

How would Kingella be confused with Neisseria and Moraxella and what would diff it from them?

Answer 31

It can grow on MTM and may not PIT the agar as it usually does; however it is distinctive on gram stain as a plump bacilli with square ends in chains, that sometimes resists decolorizing and is catalase negative (the two GN diplococci are cat positive)

pg 402

Question 32

Kingella is known for what two major types of disease and what two colony morphologies can K. kingae present on BAP?

Answer 32

A spreading, PITTING/CORRODING; or a smooth convex beta-hemolytic

It causes endocarditis in immunocomped like other HACEKs, and also bone and joint infections in pediatric populations

Question 33

Describe Eikenella corrodens isolates on CHOC, best conditions, and what infections are associated with/ types possible

Answer 33

they are fastidious gram negative coccobacilli best with increased CO2 and hemin (in CHOC); often corrode or pit the agar, appear spreading and with a bleachy odor; no growth on MAC

least common of HACEKs to cause endocarditis but it can atach to heart valves; “clenched fist wounds” from fifights, or from human bites; cellulitis in IV drug abusers due to licking the needle

Question 34

This organism more often causes endocarditis especially of tha aortic valve with large vegetations; can be falsely-gram positive and form rosettes or filaments on gram stains and is normal microbiota of nose/mouth. Oral or dental problems/procedures often precede infection.

WHat can it be confused with and how to diff?

Answer 34

Cardiobacterium hominis; It weakly ferments carbohydrates like Aggregatibacter actinomycetemcomtans but is in contrast catalse negative and indole positive

Question 35

which HACEK MUST have CO2 to grow, as opposed to just growing better?

Answer 35

C. hominis