2 - Bacteriology: Gram Positive Bacteria

Staphylococcus saprophyticus

Gram Positive Cocci, Catalase (+), Coagulase (-), Novobiocin resistant,

Nitrite negative, whitish, non-hemolytic colonies on blood agar

Staphylococcus epidermidis

Gram Positive Cocci, Catalase (+), Coagulase (-), Novobiocin sensitive, whitish, non-hemolytic colonies on blood agar

Staphylococcus aureus

habitat: human nose (anterior nares) and skin

Gram Positive Cocci, Catalase (+), Coagulase (+), b-hemolytic yellow or golden colonies on blood agar, salt-tolerant on mannitol salt agar, DNAse- positive

Protein A

Virulence factor of S. aureus that prevents complement activation

Fibrinolysin

(staphylokinase)

Virulence factor of S. aureus that dissolves fibrin clots

Alpha toxin

Toxin of S. aureus that causes marked necrosis of the skin and hemolysis

Involucrum

Complication of osteomyelitis; represents a thick sheath of periosteal new bonesurrounding a sequestrum

Sequestrum

Devascularized bone that becomes separated from the rest of the bone; may act as nidus for infection

Cloacae

Gap in the cortex of a bone, allows drainage of pus or other material from the bone into the adjacent tissues

Brodie Abscess

Sequestered focus of osteomyelitis arising in the metaphyseal area of a long bone

Staphylococcus aureus

Most common overall organism associated with osteomyelitis

Staphylococcus aureus,

Pseudomonas aeruginosa, Candida

Organism associated with osteomyelitis and IV drug users

Vancomycin

DOC for methicillin-resistant

SA (MRSA)

Linezolid

DOC for vancomycin-resistant SA (VRSA)

Tampon-using menstruating women or in

patients with nasal packing for epistaxis

Usual scenario in the patient's history of Toxic Shock Syndrome

Ritter disease

exfoliatin cleaves desmoglein in desmosomes;separation of epidermis at stratum granulosum

Other name for Scalded Skin Syndrome

Staphylococcus saprophyticus

2nd most common cause of UTIs in sexually active women

Staphylococcus saprophyticus

Causes Honeymoon cystitis

Staphylococcus epidermidis

Organism that is the most common cause of: prosthetic valve endocarditis, septic arthritis in prosthetic joints, ventriculoperitoneal shunt infections

Staphylococcus epidermidis

Organism associated with osteomyelitis and prosthetic joints

Streptococcus pyogenes

Habitat: Throat, skin

Gram Positive Cocci in chains

Beta-hemolytic, bacitracin-sensitive,

Lancefield group A,

positive PYR test

Streptococcus pneumoniae

Habitat: Nasopharynx

Encapsulated

Gram Positive Cocci in pairs, Catalase (-), alpha hemolysis, Optochin sensitivity (+), Bile solubility (+), Quellung reaction positive, “lancet shaped” cocci

Viridans

streptococcal sp.

no capsule

S. mitis

S. mutans

Gram Positive Cocci in chains alpha hemolytic, bile insoluble, optochin-resistant

Streptococcus agalactiae

Habitat: Urogenital

tract, lower GI

tract

Gram Positive Cocci in chains Catalase negative, beta

hemolytic, Lancefield group B,bacitracin resistant, cAMP factor positive, hydrolyze hippurate

Group D (enterococcus)

E. faecium

E. faecalis

Gram Positive Cocci in chains

Catalase negative, gamma

hemolytic,growthin 6.5% NaCl, PYRpositive

Non enterococcus

(S. bovis)

Gram Positive Cocci in chains

Catalase negative, gamma

hemolytic,no growthin 6.5% NaCl, PYRnegative

Hyaluronidase

Spreading factor of Streptococcus pyogenes

Streptolysin O

highly antigenic

causes AB formation

Oxygen labile toxin of Streptococcus pyogenes

Streptolysin S

Memory aid: “S for stable”

Oxygen stable toxin of Streptococcus pyogenes

M protein

What is the major virulence factor for the group A streptococcus which inhibits the activation of complement and protects the organism from phagocytosis. It is also the weakest point in the organism's defense.

DNase (streptodornase)

Virulence enzyme of Streptococcus pyogenes that degrades DNA in exudates or necrotic tissue

Anti streptokinase

Antibodies that decrease efficiency of streptokinase in managing MI

Anti-DNAse B

Elevated titers of these antibodies suggest antecedent skin infection

Anti streptolysin O (ASO)

>250 Todd units indicate recent or repeated infections

Elevated titers of these antibodies suggest antecedent pharyngitis

Pyrogenic exotoxin A

Superantigen similar to TSST

Erysipelas

Caused by Streptococcus pyogenes; Superficial infection extending into dermal lymphatics

Scarlet Fever

This disease presents as post-pharyngitic, due to erythrogenic toxin, seen in lysogenized strains, fever, strawberry tongue, centrifugal rash (sandpaper-like), Pastia lines

Dick test

(do not confuse this with the Schick test for diphtheria susceptibility)

Test for determining susceptibility to Scarlet Fever

Staphylococcal Toxic Shock Syndrome

Due to TSST -1, no recognizable site of pyogenic infection, blood cultures are often negative

Streptococcal Toxic Shock Syndrome

Due to exotoxin A, with recognizable site of pyogenic inflammation, blood cultures are often positive

Rheumatic fever

This disease is caused by Streptococcus pyogenes; post pharyngitis; due to cross-reacting antibodies to M proteins and antigens of joint, heart, and brain tissue, with marked tendency for reactivation with recurrent

streptococcal infections; Chemoprophylaxis is needed

Glomerulonephritis

This disease is caused by Streptococcus pyogenes; post skin and pharyngitis;, M protein incites immune complex deposition on the

glomerular basement membrane, not reactivated by recurrent streptococcal infections

Joints – polyarthritis

♥️ - Carditis

Nodules (subcutaneous)

Erythema marginatum

Sydenham chorea (St. Vitus Dance)

What are the major criteria of J♥️NES CRITERIA?

arrowhead shaped zone of hemolysis perpendicular to S. aureus streak

What is the positive result of the CAMP test (Christie, Atkins, Munch-Petersen test)?

urinary tract infection in pregnant women,

neonatal pneumonia, sepsis and meningitis

Diseases caused by Streptococcus agalactiae?

E. faecalis

Organism associated with endocarditis in patients who underwent GIT surgery

S. bovis

Organism associated with Marantic endocarditis in patients with abdominal malignancy

capsular swelling when mixed with a small

amount of antiserum (serum with antibodies to the capsular antigens) and

methylene blue

What is the positive result in the Quellung reaction?

Streptococcus pneumoniae

Klebsiella pneumoniae

Haemophilus influenzae

Pseudomonas aeruginosa

Neisseria meningitidis

Salmonella typhi

B group streptococci

Memory Aid:

SomeKillersHavePrettyNice andShinyBodies

Examples of

encapsulated bacteria

Streptococcus pneumoniae

Organism associated with Otitis media, sinusitis, meningitis and septic shock

in post splenectomy patients

S. mutans

Viridans streptococci associated with dental caries

S. sanguis

Viridans streptococci associated with subacute bacterial endocarditis (SBE) (Most common cause of subacute and native valve endocarditis)

S. intermedius

Viridans streptococci associated with brain abscesses

Nutritionally variant Streptococci

(Abiotrophia and Granulicatella)

Also referred to as Satelliting streptococci; Requires cysteine or pyridoxal (Vitamin B6) for growth

Bacillus anthracis

Spore forming gram positive rods, aerobic, nonmotile,

box-car-shaped, encapsulated, non hemolytic, String of pearls reaction on Mueller Hinton agar with

Penicillin, Penicillin susceptible, Medusa head morphology

Bacillus cereus

Spore forming gram positive rods, aerobic, motile, non-encapsulated, wide zone of beta hemolysis, Penicillin resistant

Bacillus cereus

Organism associated with reheated fried rice

Bacillus anthracis

Organism which causes Woolsorter's disease (Inhalational Anthrax), used in bioterrorism

Cutaneous Anthrax

Caused by Bacillus anthracis; Malignant pustule with subsequent eschar and central necrosis

Clostridium Tetani

Anaerobic, gram-positive, spore-forming rods, spore is at one end (terminal spore)

(tennis racket appearance), Lipase positive

Metronidazole (400mg rectally or 500 mg IV every 6 h for 7 days)

Preferred antibiotic for Clostridium Tetani

Penicillin (100,000–

200,000 IU/kg per day), although this drug theoretically may

exacerbate spasms (Harrisons)

Alternative antibiotic for Clostridium Tetani

1. Symmetric descending flaccid paralysis (with prominent

bulbar involvement)

2. Absence of fever

3. Intact sensorium

Triad of botulism

Infant Botulism (Floppy Baby Syndrome)

Agent: Clostridium Botulinum

Disease associated with babies ingesting spores found in household dust or honey

Clostridium Botulinum

Organism associated with preserved food like alkaline vegetables, smoked fish, canned goods (bulging), honey

C. perfringens

Organism associated with Double zone of hemolysis, Stormy fermentation of

milk; reverse CAMP positive, Lecithinase, and Alpha toxin

Egg Yolk Agar

Culture medium used for the isolation of C. perfringens?

C. difficile

Organism associated with Pseudomembranous

colitis, antibiotic associated

diarrhea, with Distinct Horsebarn odor on CCFA agar

Corynebacterium diphtheriae

Also known as Klebs-Loeffler bacillus, looks like Chinese characters, associated with thick, gray, pseudomembranes over tonsils and throat, “Bull neck”

Heart and nerves

Myocarditis - A-V conduction block, dysrhythmia

Neural involvement: peripheral nerve palsies, GBS, palatal paralysis, neuropathies, cranial nerve and/or muscle paralysis

Complications of Corynebacterium diphtheriae infections can involve which tissues?

Modified Elek test

Test for detection of toxigenicity of Corynebacterium diphtheriae

ShigA-like toxin (EHEC)

Botulinum toxin

Cholera toxin

Diphtheria toxin

Erythrogenic toxin

(S. pyogenes)

Memory Aid: “ABCDE of beta-prophage encoded toxins”

Beta-prophage encoded

toxins

Listeria monocytogenes

Aerobic, non-spore-forming, gram-positive rods, tumbling motility, cold enhancement, associated with ingestion of unpasteurized milk products

Early-Onset Neonatal Listeriosis

(granulomatosis infantiseptica)

Disease caused by Listeria monocytogenes, thru transplacental transmission, characterized by late miscarriage or birth complicated by sepsis, multiorgan abscesses, and disseminated granulomas

Erysipelothrix rhusiopathiae

Gram positive rod, H2S producer (unique among gram positive rods), associated with fishermen, handlers, abattoir workers

Erysipelothrix rhusiopathiae

Causative agent of Erysipeloid, Seal finger or Whale finger

Actinomyces Israelii

Treatment: Penicillin

S – N – A – P (Sulfa for Nocardia; for Actinomyces, use Penicillin)

Anaerobic with branching filaments, associated with local trauma (broken jaw or dental extraction), PE: hard, nontender swelling with sinus tracts draining sulfur

granules; molar tooth colonies, non-acid fast;Lumpy Jaw; PID with IUDs

Nocardia Asteroides

Treatment: Sulfonamide (TMP -SMX)

Aerobic with branching filaments, weakly acid fast, Associated with Subacute to chronic pulmonary infection (main manifestation) Mycetomas, Lung and brain abscesses