Gram + Bacilli Flashcards by Denisse Tiangco

Non branching
Non spore forming
Gram + rods/bacilli

Only species of Listeria pathogenic for humans

Once phagocytosed by WBCs, it produces Listeriolysin O + phospholipase enabling it to escape from WBC and spreads to blood stream -> reaches CNS and placenta

Listeria monocytogenes

How well did you know this?

Not at all

Perfectly

Listeria motility pattern

Tumbling motility of saline suspensions of colonies

occur at RT but rarely 5 deg

How well did you know this?

Not at all

Perfectly

Tumbling motility
Inverted Christmas tree pattern

Across placenta or by contact during delivery

Ingestion of unpasteurized milk products (eg. cheese)

High risk group: pregnant women, neonates and immunocompromised

Pregnant women

Listeria monocytogenes

How well did you know this?

Not at all

Perfectly

Listeria infection in pregnant most commonly occurs in

third trimester

How well did you know this?

Not at all

Perfectly

Listeria risk factors

Bacteremia
Amnionitis
Premature labor or septic abortion in 3-7 days

How well did you know this?

Not at all

Perfectly

Unpasteurized milk organisms

Brucella

Listeria

How well did you know this?

Not at all

Perfectly

Neonatal sepsis
Neonata meningitis
Neonatal pneumonia

Group B Agalactiae
E coli
Listeria

How well did you know this?

Not at all

Perfectly

Stillbirth
Granulomatosis infantisepticum (1st 4 days of life)
Meningitis
Meningoencephalitis
Brain abscess
Pneumonia

Listeria monocytogenes

How well did you know this?

Not at all

Perfectly

Unpasteurized milk

Cabbage/coleslaw

Listeria

How well did you know this?

Not at all

Perfectly

Listeria Tx

Ampicillin +/- Gentamycin

How well did you know this?

Not at all

Perfectly

Ampicillin + Gentamycin SE

Nephrotoxicity

How well did you know this?

Not at all

Perfectly

Aminoglycoside SE

Ototoxicity

Nephrotoxicity

How well did you know this?

Not at all

Perfectly

Ampicillin SE

Interstitial nephritis

How well did you know this?

Not at all

Perfectly

Catalase -
Non spore forming 
Non motile
Anaerobic
Gram + bacillus

Short rod with rounded ends occurs singly in short chains or in non branching filaments

Erysipelothrix

How well did you know this?

Not at all

Perfectly

Animals to humans (skin wound produced by contaminated objects or in contact with blood, flesh, viscera or feces of infected animals)

At risk of infection, butchers, abattoir workers, fishermen, fish handlers, poultry processors and veterinarians

Erysipelothrix

Rhusiopathiae

How well did you know this?

Not at all

Perfectly

Erysipelothrix virulence factors

Capsule
Neuraminidase
Hyaluronidase
Surface proteins

How well did you know this?

Not at all

Perfectly

Most common form of erysipeloid

Pain, swelling, cutaneous eruption (slowly progressive, slightly elevated, violaceous zones around the site of inoculation)

Local cutaneous infection Erysipelothrix Rhusiopathiae

How well did you know this?

Not at all

Perfectly

Best specimen for culture of Erysipelothrix

Biopsy

Tissue aspirates from erysipeloid lesions

How well did you know this?

Not at all

Perfectly

Pipe cleaner pattern of growth in Gelatin Stab cultures incubated at 22 deg C

Erysipelothrix rhusiopathiae

How well did you know this?

Not at all

Perfectly

Erysipelothrix rhusiopathiae tx

Penicillin

How well did you know this?

Not at all

Perfectly

Most are Catalase -
Round terminal spores
Drumstick

True exotoxin

C tetani

How well did you know this?

Not at all

Perfectly

Catalase +
Oval, subterminal spores
Tennis rackets

True exotoxin

C botulinum

How well did you know this?

Not at all

Perfectly

Motile, drumstick appearance

Tetanospasmin inhibits GABA and Glycine

Muscle spasm, lock jaw, risus sardonicus, respiratory paralysis, opistothonusc

Dysautonomia

C tetani

How well did you know this?

Not at all

Perfectly

C tetani tx

Metronidazole
Antitoxin 
Tetanus toxoid 
Spasmolytic drug
Penicillin

How well did you know this?

Not at all

Perfectly

Long acting inhibitor of spasm

Benzodiazepine - Diazepam

Very potent neurotoxin and probably is solely responsible for the disease

Tetanospasmin Tetanolysin

Spores germinate under anaerobic condition in the wound

C tetani

Protease that cleaves the proteins involved in the release of glycine from Renshaw cells of sc Continuous stimulation by excitatory transmitter

Tetanus toxin (tetanospasmin)

Most common form of tetanus

Generalized tetanus

Earliest manifestation of generalized tetanus

Trismus | Lock jaw

Earliest manifestation of neonatal tetanus

Poor suck

Penicillin should not be used for c tetani because

it inhibits glycine

``` Nonmotile Double zone of hemolysis Alpha toxin (lecithinase) Clostridial myonecrosis Nagler reaction + ```

Clostridium perfringens

C perfringens Tx If with gas gangrene

Penicillin Clindamycin Add hyperbaric oxygen

C perfringens toxins

Lecithinase | Exotoxins

C perfringes in culture

Stormy fermentation Litmus milk cultures turbidity gas

Spectrum of C perfringens

Gas gangrene - pain, edema, cellulitis with crepitation, hemolysis and jaundice Food poisoning - 8-16 h incubation period; characterized by watery diarrhea with cramps and little vomiting; resolves within 24 h

Nagler’s reaction in C perfringens tests

Lecithinase activity of alpha toxin

Gram + | Alpha toxin producing lecithinase

C perfringens

Myonecrosis Skin crepitation Gangrenous wound Death march of bataan

C perfringens

Areas susceptible to gas gangrene

Axilla Thigh Buttocks

C botulinum presentation Lipase +

Foodborne - preformed toxin Infant - ingestion of spores Wound - contamination with spores

Botulinum toxin blocks transmission of the neurotransmitter from motor nerve

Acetylcholine

Food poisoning Floppy baby syndrome When babies ingest spores found in household dust or honey Due to absence of competitive bowel microbes Improperly canned or preserved food

C botulinum

Can contain spores of bacteria and should not be fed to babies less than 1 year of age

Honey

diplopia, dysphonia, dysarthria, dysphagia: bulbar signs Anticholinergic effects from blockade of Ach: dry mouth, constipation, abdominal pain Bilateral descending flaccid paralysis Respiratory paralysis

C botulinum

Traumatic implantation and germination of spores at the wound site

C botulinum

Reheated fried rice

Bacillus cereus

Reheated meat dishes

C perfringens

Soft cheeses, deli, coleslaw

Listeria monocytogenes

Honey | Home canned goods

C botulinum

Unpasteurized milk products

L monocytogenes

Motile Toxin A - diarrhea Toxin B - cytolytic to colonic epithelial cells Pseudomembranous colitis

C difficile

C difficile producing drugs

Clindamycin Cephalosporin (cefotaxime, ceftriaxone, cefuroxime, ceftaz) Amoxicillin Ampicillin Quinolone (ciprofloxacin, levofloxacin, moxifloxacin)

C difficile Tx

Metronidazole - mild to moderate Vancomycin - more effective, for severe Fidaxomicin (macrolide) Causative antibiotic should be withdrawn Sx for toxic megacolon

Acquired exogenously most frequently in the hospital or nursing home Hospitalized at least 3-5 days

C difficile

C difficile toxin

``` Toxin A (enterotoxin) Toxin B (cytotoxin) ```

Pseudomembranes of PMC are confined to colonic mucosa Whitish plaques Nonbloody diarrhea with pseudomembranes (yellow white plaques) on colonic mucosa Toxic megacolon can occur

C difficile

Most common presentation of C difficile

Diarrhea

Most sensitive test for c difficile

Stool culture

C difficile Dx

Cell culture cytotoxin test on stool enzyme immunoassay for C difficile common antigen in stool Colonoscopy or sigmoidoscopy

Facultative anaerobe Grow best in inc CO2 Young colonies - Spider colonies (thin radiating filaments)

Actinomyces israelii

Old colonies “molar tooth”

Actinomyces israelii

Bacteria that thrive inc CO2

Capnophiles

Mycetomas Genital actinomycosis Lumpy jaw with skin lesions - sulfur granules

Actinomyces israelii

Actinomyces Tx

Ampicillin/sulbactam Chloramphenicol Imipinem Ticarcillin/Clavulanic acid

Causes seizure

Imipinem

Chloramphenicol causes gray baby syndrome because they lack the enzyme

Glucoronyl transferase

Renal dihydropeptidase inhibitor Added to imipinem to prevent degradation

Cilastin

Clavulanic acid MOA

Beta lactam inhibitor

Causes bone marrow supression

Chloramphenicol

Aerobe | Non acid fast

``` Actinomadura Streptomyces Tsukumurella Nocardiopsis Rhodococcus ```

Aerobe, weakly or partially acid fast

Nocardia

Anaerobe, non acid fast Filamentous branching Sulfur granules

Anctinomyces israelii

Actinomyces Tx

Peniillin

Nocardia tx

TMP-SMX SNAP Sulfo (TMP-SMZ) - Actinomyces

Gram + actinomycete Whipple’s disease (middle aged males), diarrhea, weight loss, arthralgia, lymhpadenopathy, hyperpigmentarion Warthin starry stain Infective endocarditis

Tropheryma whippeli

T whippeli Dx

PCR

T whippeli Tx

Penicillin Colchicine SXT

Warthin starry stain

H pylori Legionella Bartonella Spirochetes

Found in soil and plant materials Transmission in environmental person-to-person 2 forms

Pulmonary (farmer’s lung) | Cutaneous (mycetoma) - contain sulfur granules

Nocardia asteroides Dx

Acid fast “paraffin bait” technique

Long thin, beaded, branching, gram + bacilli Most distinguishing quality of Partially acid fast Differentiated them from Actinomyces (similar GS appearance but not acid fast) Partial acid fastness: enhanced using Middlebrook 7H10 agar or litmus milk broth Clinical infections: members of the Nocardia asteroides

Nocardia

Nocardia asteroides complex

Nocardia cyriageorgica Nocardia farcinica Nocardia nova Less common: Nocardia brasiliensis Rare: Nocardia otitisis caviarum

Phagocytosed by alveolar cell Granuloma formation Lymphocutaneous disease

Nocardia

Gram negative Aerobic Coccobacilli Incubation: 7-10 days no symptoms

B pertussis

1-2 weeks Rhinorrhea, malaise, sneezing, anorexia Highest microbiologic yield Most contagious

Catarrhal

2-4 weeks; repetitive cough with whoops, vomiting, leukocytosis

Paroxysmal

3-4 weeks Diminished cough, secondary complications (pneumonia, seizure, encephalopathy)

Convalescent

ADP ribosylation of B pertussis

Capsule Pertussis Toxin

B pertussis toxin

Dermonecrotic toxin (DNT) Capsule Pertussis Toxin Tracheal cytotoxin

B pertussis medium

Border Gengou medium | Regan-Lowe medium

DPT vaccine that causes seizure

Pertussis

Pertussis hallmark in lab diagnosis

Lymphocytosis

Buffered Charcoal Yeast Extract Agar shows “mercury droplets” appearance

B pertussis

Colony resembling a tiny drop of mercury

Mercury droplet colonies

Whooping cough | Acute Tracheobronchitis

B pertussis

Laryngotracheobronchitis

Croup | Parainfluenza

steeple sign

Croup | Parainfluenza

Pertussis Tx 1 month age or older

Macrolide (Azithromycin, Clarithromycin, Erythromycin) | Post exposure Antimicrobial Prophylaxis

Macrolide SE when given to less than 1 month

Hypertrophic pyloric stenosis