MLS 334 Exam 3 - Enterobacterales -Mis. GNR Sp 26 Stud ... - Miscellaneous Organi ...

Enterobacterales -Mis. GNR Sp 26 Stud ... - Miscellaneous Organi ...

Enterobacteriaceae is not a what ?

Genus is a group of organisms, not a genus or species

What is the gram stain of members in Enterobacteriaceae?

gram negative bacilli or coccobacilli

What media will Enterobacteriaceae grow on?

BAP, CHOC, and MAC

What is the common name used for Enterobacteriaceae?

enterics

• Also ferment glucose

What is the expected oxidase result for almost all members of Enterobacteriaceae?

negative

• Except for Plesiomonas

What organisms of the Enterobacteriaceae class do not show motility at body temperature?

klebsiella

shigella

yersinia

What are Enterobacteriaceae environmental conditions?

facultative anaerobes (grow with or without oxygen)

How do Enterobacteriaceae colonies appear on BAP?

large and grey (possible mucoid and beta hemolysis)

What do pathogens look like on a SMAC plate?

colorless possible E. coli O157:H7

What does normal flora look like on a SMAC plate?

pink/red

What do pathogens look like on a HE plate?

blue/green color with a black point - with or without black point - pathogens Salmonella and Shigella

What does normal flora look like on an HE(Hektoen enteric) plate?

orange color

What do pathogens look like on an XLD plate?

clear/red = shigella

red with black centers = salmonella

What does normal flora look like on an XLD plate?

yellow color or with black centers

What organism is the SMAC plate screening for?

E. coli O157:H7

What is E. coli O157:H7 colony morphology?

colorless on SMAC

What is an extended spectrum beta lactamase (ESBL)?

can be produced by gram-negative bacteria, rending cephalsoporins and other beta-lactam antibiotics inactive. These genes can be transmitted between organsims through plasmid conjugation (carries drug resistance gene)

antibiotic resistance through plasmids

Where are O antigens found?

cell wall (somatic)

Where are H antigens found?

flagellar antigen → motility

Where are K antigens found?

capsule antigen

Enterobacterales Clinical Significance

Most reside in GI tract → Except Salmonella, Shigella and Yersinia

Opportunistic pathogens

• Normal flora

• Cause infections in "not normal" sites

• - Septicemia, wounds, UTI, meningitis

Primary Enterobacteriaceae Pathogens

salmonella

shigella

yersinia

What is the location in the human body of most members of Enterobacteriaceae?

GI tract

What organism is the #1 cause of urinary tract infections?

Escherichia coli (E. coli)

Enterotoxigenic (ETEC)

Traveler’s Diarrhea

Which type of E. coli infection can cause blood in the stool and lead to hemolytic uremic syndrome?

Enterohemorrhagic (EHEC) → E. coli O157:H7 makes Shiga toxin and identified by SMAC

Extraintestinal Infections From E. coli

Septicemia and meningitis

· 40% of all gram negative meningitis among neonates

. Newborn acquires infection in birth canal during/right before delivery

. Capsule antigen K1

- Virulence factor associated with neonatal meningitis

E. coli Colony Morphology

dry, pink colonies; may be LF or NLF, produce a haze in the agar

E. coli Tests

oxidase negative and indole positive - not swarming

Klebsiella pneumoniae Colony Morphology

LF, moist/mucoid

Klebsiella pneumoniae Tests

indole negative

Klebsiella pneumoniae Virulence

Polysaccharide Capsule and prevents phagocytosis and antimicrobials

What are the most common species of Enterobacter?

Enterobacter cloacae and Klebsiella aerogenes.

Enterobacter cloacae and Klebsiella aerogenes. Colony Morphology on MAC Plate

LF (pink)

Indole negative

Citrobacter Species

. 12 species

. Citrobacter freundii is most common

• Nosocomial UTIs, pneumonias, endocarditis in drug users, intra-abdominal abscesses

. Identification characteristics

• Weak urease

• Lactose fermenter

What organism is highly resistant to antimicrobials and can produce a red pigment at room temperature?

Serratia marcescens

Proteus Colony Morphology

NLF, swarms on BAP, distinct bad smell

Proteus vulgaris Test ID

indole postive - does not swarm as much as Proteus mirabilis

Proteus mirabilis Test ID

indole negative

Salmonella

. Inhabit Gl tracts of animals

. Infection through contaminated or undercooked animal food products

Shigella

. Human carriers coupled with improper sanitary conditions and poor personal hygiene

Salmonella Colony Morphology

clear, NLF (MAC) and black center (HE and XLD)

Salmonella Tests

indole negative

urease positive

most produce H2S

Salmonella Virulence Factors

- Fimbriae required for adhesion to intestine

- Invasion factors (ability to transverse intestinal mucosa)

- Enterotoxin involved in gastroenteritis

Salmonella Antigenic Structures

O and H antigens

capsular antigen Vi

Salmonella Clinical Manifestations

-Acute gastroenteritis (food poisoning)

-septicemia/bacteremia

-enteric (typhoid fever)

Salmonella is caused by

organism not by toxins

Poultry,milk,eggs, pet handinling

Symptoms 8-36 hours

What organism is the major cause of Typhoid fever?

Salmonella enterica - typhi serotype

Shigella Colony Morphology on MAC

clear/NLF

Shigella Colony Morphology on HE

blue/green color with black point

Shigella Colony Morphology on XLD

colorless/red from agar

Shigella Clinical Manifestation

Low inoculum:10-200 organism

fever, chills, cramps, watery diarrhea, bloody mucus

Shigella

Nonmotile

Clear, NLF

Antigenic Structures

• O and K antigens

• Lack H antigen

• Nonmotile (SKY acronym)

What are the 4 types of Shigella species and their groups?

S. dysenteriae (Group A)

S. flexneri (Group B)

S. boydii (Group C)

S. sonnet (Group D)

fermenters

ferment carbohydrates

Nonfermenters

do not ferment carbohydrates

Gram Stain of Nonfermenters

long, thin, gram neg bacilli

Environmental Requirements of Nonfermenters

aerobic, moist, heat

What nonfermenter organism genus is seen most often in the clinical laboratory?

Pseudomonas aeruginosa

What organism has a fruity odor, metallic sheen, and is a nonlactose fermenter?

Pseudomonas aeruginosa

If you have growth of an organism on a MAC plate- do you need to perform a gram stain? Why or why not?

yes - further ID gram neg ??

Pseudomonas aeruginosa Clinical Manifestations

-HAI pneumonia, resp tract infections, bacteremia

-skin rashes (hot tub syndrome)

-ear infections

-endocarditis

-wound infections and burn patients

-pulmonary infections (CF patients)

• hot tub syndrome

Which organism can cause very serious lung complications in patients with cystic fibrosis?

Burkholderia cepacia

What is the oxidase result for most nonfermenters?

positive

Which 2 organisms highlighted in lecture have a negative oxidase result?

S. maltophilia

Enterobacteriaceae?

What is different about the gram stain in Acinetobacter spp.?

pleomorphic forms and coccoid

Acinetobacter Colony Morphology

purple hue on MAC but NLF (sacrolytic)

Acinetobacter Clinical Manifestations

UTI, pneumonia, endocarditis, septicemia, meningitis, wounds, burns, eye infections

S. Maltophilia Colony Morphology

"Blue hue on MAC agar

"Nonfermenting, gram negative rod

"Oxidase negative

"Catalase positive

S. Maltophilia Clinical Manifestations

resp infection, pneumonia, endocarditic, wound infections, bacteremia

What organism produces a weak, slow positive oxidase reaction nonfluorescent yellow or green pigment?

Burkholderia cepacia

What two nonfermentive gram negative rods have flagella?

Alcaligenes

Achromobacter

oxidase positive

What is the gram stain for Neisseria species and Moraxella catarrhalis?

gram negative diplococci (may be intra or extracellular)

Is a gram stain recommended for a pharyngeal swab of N. gonorrhoeae?

No

Using CTA, what carbohydrate does N. gonorrhoeae test positive for?

glucose

What contributes to the epidemiolgy of N. meningitidis?

crowded living conditions (military and college dorms)

N. meningitides Clinical Manifestations

Septecemia

Meningitis

Meningococcemia

Hemorrhage in adgrenal glands (Waterhouse-Friderchsen syndrome)

What is the colony morphology for N. meningitidis?

medium, grey, possibly mucoid

What CTA sugars is N. meningitidis positive for?

glucose and maltose

Does N. meningitidis need to be worked up under a hood?

Yes

Which organism tests positive using a butyrate esterase reaction?

M. catarrhalis

What is the gram stain for Haemophilus?

gram negative bacilli/coccobacilli

What are the growth factors for Haemophilus?

X and V

What is satellitisim?

the growth of fastidious organism around other bacteria that release the necessary growth factors

Will Haemophilus grow on either a BAP or MAC?

no - only has X factor

What are anaerobes?

Anaerobes are organisms that grow without air and require oxygen-free conditions to live.

What are exogenous anaerobes?

organisms that are outside the body

What are endogenous anaerobes?

organism inside the body that become source of infection

What are potential factors for anaerobic infections?

trauma

vascular stasis

reduced environment (wound)

What are common sites for anaerboes within the body?

Skin

Respiratory tract

GI tract

Genitourinary tract

What are obligate anaerobes?

organisms that cannot survive in the presence of oxygen

Where would growth be seen in broth if anaerobes are present?

the bottom of the tube

Neisseria spp. General Characteristics

"Gram stain: gram negative diplococci intracellular and extracellular

" Kidney bean or baby butt

Aerobic

"Nonmotile

Nonspore forming

Catalase positive

"Oxidase positive

asymptomatic infection is uncommon in men

and 50 % of owmen can be asymptomatic

N. gonorrhoeae

only positive for glucose

N. meningitides infection

postive for both glucose and maltose and if any specimens needed to worked up under a hood if suppites for this