1 Staph, Strep, Neisseria

7/24/2019 1 Staph, Strep, Neisseria

1/79

Staphylococci

Coagulase-negative staphylococcus; frequently involved innosocomial and opportunistic infections

S. epidermidis lives on skin and mucous membranes;endocarditis, bacteremia, UT

S. hominis lives around apocrine s!eat glands

S. capitis live on scalp, face, e"ternal ear

#ll $ may cause !ound infections by penetrating throughbroken skin

S. saprophyticus infrequently lives on skin, intestine,vagina; UT

%


2/79

&eneral Characteristics of

the StaphylococciCommon inhabitant of the skin and mucous membranes

Spherical cells arranged in irregular clusters

&ram-positive

'ack spores and flagella

(ay have capsules

$% species

)


3/79

S. aureus morphology

$


4/79

Staphylococcus aureus

&ro!s in large, round, opaque colonies

*ptimum temperature of $+oC

acultative anaerobe

ithstands high salt, e"tremes in p., and high

temperatures

/roduces many virulence factors

0


5/79

1lood agar plate, S. aureus

2


6/79

3irulence factors of S. aureusEnzymes4

Coagulase coagulates plasma and blood; produced by 5+6 of

human isolates; diagnostic

.yaluronidase digests connective tissue

Staphylokinase digests blood clots

78ase digests 78#

'ipases digest oils; enhances coloni9ation on skin

/enicillinase inactivates penicillin

:


7/79

3irulence factors of S. aureus

Toxins4

Hemolysins, ?@ lyse red blood cells

Leukocidin lyses neutrophils and macrophagesEnterotoxin induce gastrointestinal distress

Exfoliativetoxin separates the epidermis from the

dermis

Toxic shock syndrome toxinTSST@ induces

fever, vomiting, shock, systemic organ damage

+


8/79

A


9/79

Bpidemiology and /athogenesis

/resent in most environments frequented by humans

eadily isolated from fomites

Carriage rate for healthy adults is )D-:D6

Carriage is mostly in anterior nares, skin, nasopharyn",intestine

/redisposition to infection include4 poor hygiene andnutrition, tissue inEury, pree"isting primary infection,

diabetes, immunodeficiency

ncrease in community acquired methicillin resistance -(S#

5


10/79

Staphylococcal7isease

ange from locali9ed to systemic

Localized cutaneous infections invade skin through

!ounds, follicles, or glands

Folliculitis superficial inflammation of hair follicle; usuallyresolved !ith no complications but can progress

Furuncle boil; inflammation of hair follicle or sebaceous

gland progresses into abscess or pustule

Carbuncle larger and deeper lesion created by aggregationand interconnection of a cluster of furuncles

Impetigobubble-like s!ellings that can break and peel

a!ay; most common in ne!borns

%D


11/79

%%

Cutaneous lesions of S. aureus


12/79


ystemic infections

!steomyelitis infection is established in the metaphysis;

abscess forms

"acteremiaprimary origin is bacteria from another

infected site or medical devices; endocarditis possible

%)


13/79

Staphylococcal osteomyelitis in a long bone

%$


14/79


Toxigenic disease

Food intoxication ingestion of heat stable enteroto"ins;

gastrointestinal distress

taphylococcal scalded skin syndrome to"in induces

bright red flush, blisters, then desquamation of the epidermisToxic shock syndrome to"emia leading to shock and organ

failure

%0


15/79

%2

Bffects of

staphylococcal

to"ins on skin


16/79

To"ic Shock Syndrome To"in

Superantigen

8on-specific binding ofto"in to receptors triggers

e"cessive immune

response


17/79

TSS SymptomsA-%) h post infection

ever

Susceptibility to Bndoto"ins.ypotension

7iarrhea

(ultiple *rgan System ailure

Brythroderma rash@


18/79

TSS Treatment

Clean any obvious !ounds and remove any foreign

bodies

/rescription of appropriate antibiotics to eliminate

bacteria

(onitor and manage all other symptoms, eFgF

administer 3 fluids

or severe cases, administer methylprednisone, a

corticosteriod inhibitor of T8-a synthesis


19/79

dentification of Staphylococcusin

Samples

requently isolated from pus, tissue e"udates, sputum, urine,

and blood

Cultivation, catalase, biochemical testing, coagulase

%5


20/79

Catalase test

)D


21/79

)%


22/79

Clinical Concerns and Treatment

526 have penicillinase and are resistant to penicillin andampicillin

(S# methicillin-resistant S. aureus carry multiple

resistance

Some strains have resistance to all maEor drug groups e"cept

vancomycin

#bscesses have to be surgically perforated

Systemic infections require intensive lengthy therapy

))


23/79

/revention of Staphylococcal nfections

Universal precautions by healthcare providers to prevent

nosocomial infections

.ygiene and cleansing

)$


24/79

&eneral Characteristics of Streptococci

&ram-positive sphericalGovoid cocci arranged in longchains; commonly in pairs

8on-spore-forming, nonmotile

Can form capsules and slime layers

acultative anaerobes

7o not form catalase, but have a pero"idase system

(ost parasitic forms are fastidious and require enriched

media

Small, nonpigmented colonies

Sensitive to drying, heat, and disinfectants

)0


25/79

reshly isolatedStreptococcus

)2


26/79

Streptococci

'ancefield classification system based on cell !all #g %+groups #, 1, C,HF@

#nother classification system is based on hemolysisreactions

-hemolysis #, 1, C, & and some 7 strains

hemolysis S. pneumoniaeand others collectivelycalled viridans

):


27/79

.emolysis patterns on blood agar

)+

.uman Streptococcal


28/79

.uman Streptococcal

/athogens

S. pyogenes

S. agalactiae

3iridans streptococci

S. pneumoniae

Enterococcus faecalis

)A


29/79

)5


30/79

-hemolytic S. pyogenes

(ost serious streptococcal pathogen

Strict parasite

nhabits throat, nasopharyn", occasionally skin

$D


31/79

3irulence actors of-.emolyticS. Pyogenes

/roduces surface antigens4

C#carbohydrates protect against lyso9yme

Fimbriae adherence

$#protein contributes to resistance to phagocytosis

.yaluronic acid capsule provokes no immune response

C2a protease hinders complement and neutrophil response

$%


32/79

3irulence actors of-.emolytic

S. Pyogenes

B"tracellular to"ins4

treptolysins hemolysins; streptolysin * S'*@ andstreptolysin S S'S@ both cause cell and tissue inEury

Erythrogenic toxin %pyrogenic& induces fever and typical redrash

uperantigens strong monocyte and lymphocyte stimulants;cause the release of tissue necrotic factor

$)

3i l f . l i


33/79

3irulence actors of-.emolyticS. Pyogenes

Extracellular enzymes

Streptokinase digests fibrin clots

.yaluronidase breaks do!n connective tissue

78ase hydroly9es 78#

$$


34/79

Bpidemiology and /athogenesis

.umans only reservoir

napparent carriers

Transmission contact, droplets, food, fomites

/ortal of entry generally skin or pharyn"

Children predominant group affected for cutaneousand throat infections

Systemic infections and progressive sequelae possibleif untreated

$0


35/79

Scope of Clinical 7isease

Skin infectionsImpetigo %pyoderma& superficial lesions that break and

form highly contagious crust; often occurs in epidemics inschool children; also associated !ith insect bites, poor

hygiene, and cro!ded living conditions

Erysipelas pathogen enters through a break in the skinand eventually spreads to the dermis and subcutaneoustissues; can remain superficial or become systemic

Throat infections

treptococcal pharyngitis strep throat

$2


36/79

Streptococcal skin infections

$:


37/79

/haryngitis and tonsillitis

$+


38/79

Scope of Clinical 7isease

Systemic infections

carlet fever strain of S. pyogenes carrying a prophage

that codes for erythrogenic to"in; can lead to sequelae

Septicemia

/neumonia

Streptococcal to"ic shock syndrome

$A


39/79

'ong-Term Complications of &roup

# nfections

'heumatic fever follo!s overt or subclinical pharyngitis in

children; carditis !ith e"tensive valve damage possible,

arthritis, chorea, fever

(cute glomerulonephritis nephritis, increased bloodpressure, occasionally heart failure; can become chronic leading

to kidney failure

$5


40/79

&roup 14 Streptococcus Agalactiae

egularly resides in human vagina, pharyn", and largeintestine

Can be transferred to infant during delivery and cause severeinfection

(ost prevalent cause of neonatal pneumonia, sepsis, andmeningitis

/regnant !omen should be screened and treated

ound and skin infections and endocarditis in debilitated

people

0D


41/79

&roup 7 Bnterococci and &roups C and

& Streptococci

&roup 74

Enterococcus faecalis, E. faecium, E. durans

8ormal colonists of human large intestine

Cause opportunistic urinary, !ound, and skin infections,particularly in debilitated persons

&roups C and &4

Common animal flora, frequently isolated from upper respiratory;pharyngitis, glomerulonephritis, bacteremia

0%


42/79

dentification

Cultivation and diagnosis ensure proper treatment to preventpossible complications

apid diagnostic tests based on monoclonal antibodies that react

!ith C-carbohydrates

Culture using bacitracin disc test, C#(/ test, Bsculin hydrolysis

0)


43/79

Streptococcal tests

0$


44/79

-hemolytic streptococci

00


45/79

02


46/79

Treatment and /revention

&roups # and 1 are treated !ith penicillin

'ong-term penicillin prophyla"is for people !ith a history

of rheumatic fever or recurrent strep throat

Bnterococcal treatment usually requires combined therapy

0:

-.emolytic Streptococci4


47/79

.emolytic Streptococci43iridans &roup

'arge comple" group

Streptococcus mutans, S. oralis, S. salivarus,

S. sanguis, S. milleri, S. mitis

(ost numerous and !idespread residents of the gums and teeth,oral cavity, and also found in nasopharyn", genital tract, skin

8ot very invasive; dental or surgical procedures facilitateentrance

0+


48/79

3iridans &roup

1acteremia, meningitis, abdominal infection, tooth abscesses

(ost serious infection subacute endocarditis 1lood-bornebacteria settle and gro! on heart

lining or valves

/ersons !ith pree"isting heart disease are at high risk

Coloni9ation of heart by forming biofilms

0A


49/79

3iridans &roup

S. mutansproduce slime layers that adhere to teeth, basisfor plaque

nvolved in dental caries

/ersons !ith pree"isting heart conditions should receiveprophylactic antibiotics before surgery or dental

procedures

05

Streptococcus Pneumoniae4 The


50/79

Streptococcus Pneumoniae4 The

/neumococcus

Causes :D-+D6 of all bacterial pneumonias

Small, lancet-shaped cells arranged in pairs and short chains

Culture requires blood or chocolate agar

&ro!th improved by 2-%D6 C*)

'ack catalase and pero"idases cultures die in *)

2D


51/79

T!o effects of streptococcal coloni9ation

2%


52/79

7iagnosing Streptococcuspneumoniae

2)


53/79

S. Pneumoniae

#ll pathogenic strains form large capsules maEor virulencefactor

Specific soluble substance SSS@ varies among types

5D different capsular types have been identified

Causes pneumonia and otitis media

2$


54/79

Bpidemiology and /athology

2-2D6 of all people carry it as normal flora in thenasopharyn"; infections are usually endogenous

3ery delicate, does not survive long outside of its habitat

Ioung children, elderly, immune compromised, those!ith other lung diseases or viral infections, personsliving in close quarters are predisposed to pneumonia

/neumonia occurs !hen cells are aspirated into thelungs of susceptible individuals

/neumococci multiply and induce an over!helminginflammatory response

&ains access to middle ear by !ay of eustachian tube

20


55/79

The course of bacterial pneumonia

22


56/79

Cultivation and 7iagnosis&ram stain of specimen presumptive identification

Juellung test or capsular s!elling reaction


57/79


Traditionally treated !ith penicillin & or 3

ncreased drug resistance

T!o vaccines available for high risk individuals4

Capsular antigen vaccine for older adults and other high riskindividuals effective 2 years

ConEugate vaccine for children ) to )$ months

2+

Morphology


58/79

Morphology

StreptococcusStaphylococcus


59/79

StreptococcusStaphylococcus


60/79

amily 8eisseriaceae&ram-negative cocci

esidents of mucous membranes of !arm-blooded animals

&enera includeNeisseria, Branhamella, Moraxella

) primary human pathogens4Neisseria gonorrhoeae

Neisseria meningitidis

:D


61/79

Neisseria

:%

&


62/79

&enusNeisseria&ram-negative, bean-shaped, diplococci

8one develop flagella or spores

Capsules on pathogens

/ili

Strict parasites, do not survive long outside of the host

#erobic or microaerophilic

*"idative metabolism

/roduce catalase and cytochrome o"idase

/athogenic species require enriched comple" media and C*)

:)

N i i G h


63/79

Neisseria Gonorrhoeae

The &onococcus

Causes gonorrhea, an ST7

3irulence factors4

imbriae, other surface molecules for attachment; slo!s

phagocytosis

g# protease cleaves secretory g#

:$


64/79

Bpidemiology and /athology

Strictly a human infection

n top 2 ST7s

nfectious dose %DD-%,DDD

7oes not survive more than %-) hours on fomites

:0

Comparative incidence of reportable


65/79

Comparative incidence of reportable

infectious ST7s

:2

& h


66/79

&onorrhea

nfection is asymptomatic in %D6 of males and 2D6of females

(ales urethritis, yello!ish discharge, scarring,and infertility

emales vaginitis, urethritis, salpingitis /7@mi"ed anaerobic abdominal infection, commoncause of sterility and ectopic tubal pregnancies

B"tragenital infections anal, pharygeal,conEunctivitis, septicemia, arthritis

::


67/79

&onorrheal damage to the male reproductive tract

:+


68/79

#scending gonorrhea in !omen

:A


69/79

&onorrhea in 8e!borns

nfected as they pass through birth canal

Bye inflammation, blindness

/revented by prophyla"is immediately after birth

:5

7i i d C t l


70/79

7iagnosis and Control

&ram stain &ram-negative intracellular neutrophils@diplococci from urethral, vaginal, cervical, or eye

e"udate presumptive identification

)D-$D6 of ne! cases are penicillinase-producing))*+ or tetracycline resistant T'*+

Combined therapies indicated

ecurrent infections can occur

eportable infectious disease

+D


71/79

&ram stain of urethral pus

+%

Neisseria MeningitidisThe


72/79

g

(eningococcus

3irulence factors4

Capsule

#dhesive fimbriae

g# proteaseBndoto"in

%) strains; serotypes #, 1, C cause most cases

+)


73/79

Bpidemiology and /athogenesis/revalent cause of meningitis; sporadic or epidemic

.uman reservoir nasopharyn"; $-$D6 of adultpopulation; higher in institutional settings

.igh risk individuals are those living in close quarters,

children : months-$ years, children and young adults %D-)D years

7isease begins !hen bacteria enter bloodstream, crossthe blood-brain barrier, permeate the meninges, and gro!

in the cerebrospinal fluid3ery rapid onset; neurological symptoms; endoto"in

causes hemorrhage and shock; can be fatal

+$

7issemination of the meningococcus from a


74/79

7issemination of the meningococcus from a

nasopharyngeal infection

+0


75/79

*ne clinical sign of meningococcemia

+2


76/79

Clinical 7iagnosis

&ram stain CS, blood, or nasopharyngeal sample

Culture for differentiation

apid tests for capsular polysaccharide

+:


77/79


Treated !ith 3 penicillin &, cephalosporin

/rophylactic treatment of family members, medical personnel,

or children in close contact !ith patient

/rimary vaccine contains specific purified capsular antigens

++


78/79

+A

*ther &ram-8egative Cocci and


79/79

g

Coccobacilli

&enusBranhamella

Branhamella catarrhalis found in nasopharyn"4

significant opportunist in cancer, diabetes, alcoholism

&enusMoraxella1acilli found on mucous membranes

Genus Acineto!acter

Documents

1 Staph, Strep, Neisseria