Clinical Bacteriology II final review

Staphylococcus aureus general features

gram positive cocci in clusters

facultative anaerobe

beta hemolytic

non motile and non spore forming

Staphylococcus aureus infections

skin infections: furuncles, carbuncles, impetigo, Hair Follicle Infections, cellulitis, Necrotizing fasciitis

pneumonia in children

endocarditis

enterocolitis

scaled skin syndrome

food poisoning

toxic shock syndrome

chronic lower respiratory infections in cystic fibrosis patients

Human bite infections

conjunctivitis, keratitis, endophthalmitis

IV catheter associated bacteremia

staphylococcus aureus identification

grows on BAP and is beta hemolytic, mannitol salt agar, PEA

coagulase positive

catalase positive

novobiocin susceptible

can oxidize and ferment

staphylococcus aureus virulence factors

teichoic acid for adherence

enterotoxin

toxic shock syndrome toxin

hyaluronidase for spreading factor

penicillinase

MRSA is a concern

staphylococcus epidermidis general features

gram positive cocci in clusters

facultative anaerobe

non hemolytic

non motile and non spore forming

staphylococcus epidermidis infections

nosocomial infection from implantation of prosthetic devices and immunocompromised

bacteremia (is a common contaminant)

endocarditis

Burn Infections

endophthalmitis

staphylococcus epidermidis identification

grows on BAP and PEA

catalase positive

coagulase negative

can oxidize and ferment

novobiocin susceptible

staphylococcus saprophyticus general features

gram positive cocci in clusters

facultative anaerobe

non hemolytic

non motile and non spore forming

staphylococcus saprophyticus infections

UTIs (if found in high numbers may mean contamination)

staphylococcus saprophyticus identification

grows on BAP and PEA

catalase positive

coagulase negative

novobiocin resistant

streptococcus pyogenes general features

gram positive cocci in chains

aerotolerant

beta hemolytic

non motile and non spore forming

streptococcus pyogenes (group A) infections

skin: impetigo, erysipelas, necrotizing fasciitis, cellulitis

pharyngitis frequent in children between 5-15

toxin shock like syndrome

acute rheumatic fever

acute glomerulonephritis

conjunctivitis

streptococcus pyogenes identification

grows on BAP

catalase negative

bacitracin susceptible

PYR positive

streptococcus pyogenes virulence factors

M protein

hyaluronic acid capsule

streptolysin O

streptolysin S

erythrogenic toxin

DNase

Hyaluonidase

streptococcus agalactiae (group B) general features

gram positive cocci

facultative anaerobe

beta hemolytic

non motile and non spore forming

lim broth

streptococcus agalactiae (group B) infections

leading cause of pneumonia, sepsis, and meningitis during first 2 months of life

endocarditis

upper respiratory tract infections

acute meningitis in infants

bacteremia

streptococcus agalactiae (group B) identification

grow on BAP

catalase negative

hippurate hydrolysis and camp positive

polysaccharaide capsule

streptococcus pneumoniae identification

gram positive cocci in pairs

aerotolerant anaerobe

alhpa hemolytic

non motile and non spore forming

streptococcus pneumoniae infections

pneumonia in children and adults

acute meningitis in infants, children, and adults

upper respiratory infections (not pharyngitis or tonsillitis)

conjunctivits

keratitis

endophthalmitis

extravascular blood infection

streptococcus pneumoniae identification

grows on BAP

catalase negative

insulin fermentation

optochin susceptible

bile soluble

capsule

enterococcus and group D strep general features

gram positive cocci

facultative anaerobe

non motile and non spore forming

viridans strep general

gram positive cocci

facultative anaerobe

non motile and non spore forming

lack lancefield antigen

viridans strep infections

most common cause of endocarditis (dental procedures)

viridans strep identification

grows on BAP

catalase negative

optochin resistant

cannot hydrolyze BE

Corynebacterium diphtheriae general features

gram positive rods

facultative anaerobe

non motile and non spore forming

beta hemolytic

pleomorphic (Chinese letters)

uneven staining

humans are the only reservoir

Corynebacterium diphtheriae infections

respiratory: nasopharyngeal and throat, bull neck

skin lesions

laryngitis

Corynebacterium diphtheriae identification

Loeffler’s, cysteine-tellurite blood, Tinsdale, and blood agar

toxin detection

catalase positive

corynebacterium ulcerans

Animal pathogen: human contact with animals

Milder

Lower levels of toxin

corynebacterium jiekeium

Strict aerobe

Bacteremia with prosthetic devices, immunocompromised

highly resistant to antibiotics expect vancomycin

Corynebacterium urealyticum

Urine pathogen

Slow growing

Strict aerobe

catalase positive

urease positive

does not ferment glucose

Corynebacterium xerosis

Grows on SBA: dry, tan

Prosthetic valve endocarditis

Disease in immunocompromised

Corynebacterium pseudodiphthericum

Nasopharynx

Endocarditis
Infection in immunocompromised: respiratory, UTI, wound

No Chinese lettering, stains evenly and cells in parallel rows (palisades)

Corynebacterium striatum

Nasopharynx

Nosocomial infections

Arcanobacterium general features

Gram positive rods

Non-spore forming

Catalase negative

Beta hemolytic (narrow zone)

Aerobic

•and lecithinase positive

Resistant to penicillin

A. haemolyticum , A. pyogenes, A. bernardiae

Arcanobacterium haemolyticum infections

10-20 year old patients with pharyngitis

Desquamation of skins from hands and feet

Rothia

Gram positive rods, branching filaments, In broth, appear as cocci

Nitrite positive

non-motile

Urease negative

Most are catalase positive

endocarditis

Rhodococcus equi

Found in soil, causes respiratory infections in animals

Disease in immunocompromised

May demonstrate branching filaments

Partially acid fast

Salmon-pink pigment if left to incubate

Does not ferment carbohydrates

listeria monocytogenes general features

Gram positive coccobacilli

Facultative anaerobe

Pleomorphic

Non-spore forming

Beta-hemolysis

Listeria monocytogenes infections

acute meningitis in infants

extravascular blood infections

listeria monocytogenes identification

tumbling motility

Catalase positive

hippurate positive

bile esculin positive

Positive CAMP (block appearance)

Erysipelothrix rhusiopathiae general features

Gram positive , slender, filamentous bacilli

Facultative anaerobe to microaerophilic

Pleomorphic

Non-spore forming

Alpha-hemolytic

Pigs are the main reservoir

Erysipelothrix rhusiopathiae infections

Endocarditis

skin: Eysipeloid

septicemia

Erysipelothrix rhusiopathiae identification

Brush pattern at 22oC in gelatin-stab cultures

Catalase negative

hydrogen sulfide production

VP negative

Lactobacillus acidophilus general features

Gram positive

Facultative anaerobe

Highly pleomorphic, spaghetti

Non-spore forming and Non-motile

Alpha-hemolytic

Natural flora of female urogenital tract also found in mouth and GI tract

Bacillus anthracis general features

Gram positive bacillus

Aerobic

Spore-forming

non-motile

Non-hemolytic

Bacillus anthracis infections

Skin: Black scar (eschar), erythematous ring

Pulmonary: Woolsorters disease

Gastrointestinal

Bacillus anthracis identification

Swirling projections (Medusa head)

Catalase positive

produces lecithinase

Glutamic acid capsule

Susceptible to penicillin

Bacillus cereus general feautres

Gram positive bacillus

Aerobic

Spore-forming

motile

Beta-hemolytic

Bacillus cereus infections

Food poisoning from enterotxin, fried rice

Opportunistic infections: post-op eye infection, endocarditis, and bacteremia (IV drug users or immunocompromised)

Bacillus cereus identification

Catalase positive

produces lecithinase

grows on Egg yolk agar ( creates a zone of opacity)

Penicillin susceptibility

Bacillus subtilis

Gram positive bacillus

Aerobic

Spore-forming

Not part of normal flora

Rarely causes human disease

May be pigmented

Aerobic Actinomycetes

Branching filamentous hyphae

Non-spore forming

Not commonly seen in US, but can cause significant human disease

Nocardia general features

Gram stain is weak, beaded appearance

Aerobic

Branching, filamentous

weakly acid fast

Nocardia infections

Pulmonary

cutaneous: pus may contain sulfur granules

Neisseria gonorrhoeae general features

Gram negative diplococci

Aerobic

Non-spore forming and non-motile

Glucose fermenter

Not normal human flora (always pathogenic)

Usually intracellular

Neisseria gonorrhoeae infections

genital

rectal

pharyngeal

conjunctivitis

epididymitis

Neisseria gonorrhoeae identification

grows on Choc, Modified Thayer-Martin, Martin-Lewis, New York City

capsule

beta-lactamase

kidney bean shaped

catalase positive

oxidase positive

Intracellular diplococci is evidence of gonococcal infection in male urethral specimens (not female samples)

Neisseria meningitidis general features

Gram negative diplococci

Aerobic

Non-spore-forming and non-motile

Ferment glucose and maltose

Usually intracellular

Neisseria meningitidis infections

naopharyngeal

Acute meningitis in children and adolescents

extravascular blood infections

Moraxella catarrhalis geneal features

Gram negative coccobacilli or diplococci

Non-fermentative (asaccharolytic)

hockey puck appearance

Moraxella catarrhalis infections

Upper respiratory tract: children and elderly

Lower respiratory tract: adults with preexisting conditions

3rd most common cause of otitis media and sinusitis in children

Moraxella catarrhalis identification

grows on SBA and CHOC

Inhibited by colistin

Catalase positive

oxidase positive

Susceptible to: Erythromycin, tetracycline, Trimethoprim-sulfa, Ampicillin with beta-lactamase inhibitor

Neisseria cinerea

Dnase negative

Misidentified as gonococcus but is susceptible to colistin

Asaccharolytic

Neisseria flavescens

Yellow-pigment

Asaccharolytic

SBA and CHOC at RT

Neisseria lactamica

Ferment maltose, lactose, glucose

Nasopharyngeal commensal in children, peaks at 2 but declines

Positive ONPG

Morphology similar to meningococcus

Neisseria mucosa

Reduce nitrate and nitrite

Mucoid

Lacks pigments

Neisseria sicca

Dry, wrinkled breadcrumb

Commensal respiratory in adults

Neisseria subflava

Less yellow

SBA and CHOC at RT

Kingella denitrificans

Reduce nitrate

Normal flora of URT

Catalase negative

oxidase positive

infective endocarditis

Haemophilus influenzae general features

Gram negative coccobacilli

Facultative anaerobe

non-motile

ferment carbohydrates

Haemophilus influenzae infections

septicemia

cellulitis

epiglottis

pneumonia in children

acute meningitis in infants, and children

bronchitis

conjunctivitis

Chronic Lower Resp infections in Cystic fibrosis patients

extravascular blood infections

Haemophilus influenzae identification

Requires Chocolate agar: Require X (hemin) and V (NAD) factor

satellitism

capsule

catalse positive

reduce nitrates

Haemophilus aegyptius

difficult to differentiate from H. influenzae

Acute conjunctivitis

Haemophilus influenzae biogroup aegyptius

Conjunctivitis in pediatric patients

Can cause systemic disease, Brazilian purpuric fever

Haemophilus ducreyi

Not normal part of human flora

Causative agent of chancroid

grows best in 33oC, and requires special media such as GC that contains vancomycin to reduce growth of normal flora

Haemophilus parainfluenzae and Aggregatibacter aphrophilus

Endocarditis one month after dental procedures

Haemophilus aphrophilus

Gram negative pleomorphic

Ferment carbohydrates: sucrose, glucose, maltose, lactose

Catalase negative

Reduce nitrates to nitrites

Do not grow on Mac

infective endocarditis

Aggregatibacter actinomycetemcomitans

Gram negative rods

tar formation in center of colony

fermenter with addition of serum to media

Catalase positive

Oxidase variable

Negative for urease, indole, esculin, citrate

Do not grow on Mac

infective endocarditis

Cardiobacterium hominis

Gram negative pleomorphic rod

Nonmotile

Form rosettes or swellings

Ferment but needs serum to enhance reaction

Catalase negative

Oxidase positive

Indole positive

Grow on blood and CHOC agar

infective endocarditis

Eikenella corrodens

Gram negative

Nonmotile

Odor of bleach

Common cause of infection after trauma: Clench fist wounds, Dental manipulation, surgery

Catalase negative

Oxidase positive

Asaccharolytic

Human bite infections

infective endocarditis

Kingella spp

Gram negative coccobacilli or rods

Nonmotile, but may be twitching

Ferment glucose

Catalase negative

Oxidase positive

Do not grow on Mac

Capnocytophaga spp

Gram negative rods (mucoid)

Long thin tapered rods

Common cause of septicemia in granulocytopenic patients

Fermenter with addition of serum to media

Catalase negative

Oxidase negative

Do not grow on Mac

Dog/cat bites

Pasteurella multocida

Gram negative coccobacilli, filamentous, or rods

Nonhemolytic

Bipolar staining: safety pin appearance

Localized cellulitis and lymphadenitis from animal scratch or bite

Acid butt TSIA

Does not grow on OF media

Oxidase, catalase, Indole and ONPG positive

Urease negative

Dog/cat bites

Brucella

Gram negative coccobacillary

Non-spore forming, non-motile

Infection of sheep, cows, pigs, and other animals

Enriched media BAP Require thiamine, niacin, biotin

capsule

extravascular blood infections

Francisella tularensis

Gram negative coccobacilli

Facultative anaerobe

Category A select biological agent

Intracellular within macrophages

Bipolar staining

Glandular Fever, Tularemia, Rabbit Fever, Tick Fever, Deerfly Fever

Glucose-cysteine agar, CHOC with cysteine

Bordetella pertussis general features

Gram negative coccobacilli

Strict aerobe

nonmotile

appear to be pearls or drops of mercury

Humans are the only reservoir

Bordetella pertussis infections

Whooping cough

Complications: pneumonia

bronchitis

Bordetella pertussis identification

Reagan-Lowe transport medium

Direct plate coughing (best)

Bordet-Gengou

Legionella pneumophila general features

Gram negative coccobacilli

Motile

Aerobic

Facultative intracellular bacteria

lakes, rivers, hot springs, mud

Growth on BYCE agar

Legionella pneumophila infections

Legionnaire’s Disease

cutaneous abscesses

wound infections

pericarditis

myocarditis

bacteremia

community acquired pneumonia in hospitalized individuals

Uropathogenic E. coli

Most common cause of UTI

Originate in intestinal flora

Produce pili

recurrent complicated UTIs

Enterotoxigenic E. coli

Exotoxins

heat labile and heat stable

Traveler’s Diarrhea

A high infective dose

Enteropathogenic E. coli

Plasmid-borne adhesion factor (EAF) enabling adherence to mucosal cells

Outbreaks in hospital nurseries and daycares

Diarrhea; vomiting; nausea; low-grade fever; malaise; stool with mucous

Enteroinvasive E. coli

Dysentery-like illness

Direct penetration, invasion, and destruction of intestinal mucosa

do not ferment lactose

Enterohemorragic E. coli

Best known strain O157:H7

Associated with hemorrhagic colitis and HUS

Verotoxins I and II: verotoxin I

Fimbriae

MAC with sorbitol: O157:H7 does not ferment sorbitol

Salmonella identification

Non-lactose fermenters

H2S production

most are lysine decarboxylase+

Indole, VP, PAD, urease negative

Salmonella infections

Gastroenteritis

Enteric fever, Organism multiples in skin (rose spots)

extravascular Bacteremia

Asymptomatic carriage: Individuals who recover from infection may harbor organisms in gallbladder, antimicrobial therapy may be necessary or gallbladder removal

undercooked chicken, eggs, unpasteurized milk, beef gravy

Shigella general features

Not part of normal flora

Non-motile

Low infective dose

S. dysenteriae (Group A ), S. flexneri (Group B), S. boydii (Group C),S. soneii (Group D)

Shigella infections

Causes bacillary dysentery

Caused by penetration of intestinal epithelial cells following attachment to the mucosa

Shigella identification

Except for S. flexneri, they do not produce gas from glucose

Urease, H2S, decarboxylate lysine negative