Mikrobiologi Dasar ( Dr. Latre Buntaran,Spmk )

8/9/2019 Mikrobiologi Dasar ( Dr. Latre Buntaran,Spmk )

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Microbiology


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Bacteriology C/S

Plate sample on blood agar plate others

Incubate 350 30C o!ernight " # $% hours &

'ead plate (or pathogens

)o *or+,up to identi(y pathogens

)o sensiti!ity testing i( a!ailable


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-ram Stain

)i((erential staining process used in microscopyo( specimens and bacterial colonies

Bacteria di!ided into . groups o( -ram positi!e" deep blue or purple & and -ram negati!e " redor pin+ &

Can be used to di((erentiate epithelial andin(lammatory cells


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S+in lora

ransient

Microbes that happen to be deposited on the s+in but do not

multiply there1 Maybe remo!ed by a thorough *ash *ith soap and *ater

'esident

Colonise the s+in1

Cannot be remo!ed by *ashing *ith soap and *ater

Can be reduced to small numbers by disin(ectants


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ransient Bacteria

2ogenous in origin

4ocated on the s+in sur(ace

2amples areS.aureus, E.coli


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Staphylococcus

hey are -ram,positi!e cocci that appear

microscopically li+e a bunch o( grapes

S.aureus is coagulase positi!e

Coagulase negati!e staphylococci are many

in number eg1S. saprophyticus


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2pidemiology o( Staphylococcus

S.aureus is ubi6uitous1

Colonise " nares aillae perineumetc & about 308 o(humans1

Person,to,person spread by hands " common & nasaldischarges and aerosol " rare &

C7S are ubi6uitous on s+in and mucosal sur(aces1

In(ection usually endogenous and is common cause o(nosocomial line in(ections

Bacteria has lo* pathogenicity but cause in(ection inpatients *ith (oreign bodies


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Pathogenesis o(S.aureus in(ection

Colonisation usually precedes in(ection

Ma9or reser!oir !aries eg1 nose (or dialysis patients oropharyn (orintubated patients

Some (actors that promote colonisation :

Prolonged hospitalisation

)iabetics

2c;ema


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Pathogenesis o( C7S

Seldom occur among healthy indi!iduals

Important host (actors are de(ects in mucosal membrane/s+in

immunosupression and presence o( (oreign body

Patients *ith systemic or localised de(ects in opsonophagocyticacti!ity are at increased ris+ o( in(ection

In neonates administration o( I= lipid emulsion is anindependent ris+ (actor

Preceeding antibiotic therapy


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C7S In(ections

Single most important (actor associated

*ith C7S in(ections is the presence o( a

(oreign body eg1 ind*elling catheters

intra!ascular catheters CS shunts

prosthetic 9oints etc1


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Staphylococci produce disease in . *ays :

)irectly by in!asion and subse6uent :

tissue destruction *hether locally or byhaematogeneous spread

hrough the e((ects o( toins


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In(ections produced byS. aureus

)irect in!asion

)issemination " haematogenous &

oin mediated


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)irect In!asion byS. aureus

$1 Super(icial

Pyoderma including impetigo paronychia

S+in and so(t tissue in(ections eg1 boilscellulitis

.1 )eep Septic arthritis

>steomyelitis

Pyomyositis


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oin MediatedS.aureus In(ection

S+in disease eg1 staphylococcal scalded,s+in syndrome

-astrointestinal disease eg1gastroenteritis

Multisystem disease eg1 toic shoc+syndrome


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=irulence actors o(S.aureus

2n;ymes eg1 catalase hyaluronidase lipase

oins eg1 ?,toins leu+ocidin enterotoin SStoin $

Immune system (actors eg1 antigen,antibodycomplees superantigens

Cell *all components eg1 acti!ated C tn( othercyto+ines @ mediator systems


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Se6uence o( 2!ents in SeriousS.aureus In(ections

Coloni;ation carriage toin production

Barrier breach or brea+

In!asion

Bacteremia or septicaemia

Syndrome o( se!ere sepsis " acti!ated C

cyto+ines toin other mediators & Complications " suppurati!e and in(lammatory &

)eath


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Streptococcus

-ram,positi!e cocci in chains

Can be beta " clear & alpha " greenish & or non,haemolytic on blood agar plate

-roup A beta,haemolytic streptococci orS.pyogenes

=ancomycin resistant enterococci " ='2 & is animportant nosocomial pathogen


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2pidemiology o(S.pyogenes "$&

Common cause o( community,ac6uired

pharyngitis and s+in in(ections1

Carriage in throat s+in rectum " $8 &

and !agina " $8 &

4i+ely that besides contact transmission

there is airborne transmission in SSI


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2pidemiology o(S.pyogenes ".&

Implicated in burn *ound in(ections

necrotising (asciitis puerperal and

neonatal in(ections

Important as cause Acute

glomerulonephritis and Acute 'heumatic


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2pidemiology o( 2nterococci

7ormal habitat in gastrointestinal tract

'eser!oir sites are *ounds s+in " inguinalantecubital (ossa & chronic decubital ulcers!agina and perineal or meatal areas o(hospitalised males

Most important method o( spread o( ='2 isthrough transient carriage on hands o(


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Pathogenesis o( Streptococcal

oic Shoc+ Syndrome " SS &

Initial (ocus is the s+in and so(t tissues o(pre!iously healthy indi!iduals

Strains ha!e a high propensity to initiate in!asi!edisease

Pathogenesis not de(initely elucidated1 Mostinterest on pyrogenic eotoins " SP2s&

>ther !irulence properties in!ol!ed eg1 M proteinen;ymes


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Pathogenesis o( 7osocomial

In(ection by 2nterococci

-enerally enterococci are part o( normal (lora and ha!elittle pathogenic potential in normal host

>pportunistic pathogens in the elderlyimmunocompromised or *hen in!asi!e procedures aredone

4ittle +no*n about !irulence (actors

Cause DI bacteremia endocarditisintraabdominal/pel!ic in(ections s+in/so(t tissuein(ections etc1


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-ram,negati!e Bacteria

ermenters eg1Escherichia coli

7on,(ermenters , -ram , negati!e

bacteria that do not utili;e carbohydrates

as a source o( energy or degrade them

through metabolic path*ays other than(ermentation eg1Acinetobacter baumannii


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2nterobacteriaceae

amily o( (ermentati!e -7B commonly

isolated (rom clinical specimens and are

there(ore also important nosocomialpathogens1

acultati!e anaerobes that *ith (e* eceptions(erment glucose reduce nitrate to nitrite and

are oidase negati!e1


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2nterobacteriaceae eamples

Escherichia coli

Klebsiellaspecies (pneumoniae)

Enterobacterspecies

Proteus mirabilis


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Pathogenesis o( 7I caused by

2nterobacteriaceae

$1 Pathogen,speci(ic (actors

Adhesion

Capsules

Iron chelators

>ther (actors and ropisms

.1


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Adhesion

Bacterial adhesion attachment to sur(aces

colonisation o!ergro*th tissue in!asion1

Mediated by both (imbrial and non(imbrial

adhesins that are encoded on plasmids and on

the bacterial genome eg1 P (imbrae , can anchor

bacteria to uroepithelial cells cause

pyelonephritis in adults and children1


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Capsules

Can partly protect the bacteria against

the bactericidal e((ect o( serum andagainst phagocytosis eg1Klebsiellaspp1

Can also directly suppress the hostimmune response1


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Iron Chelators

Ability o( some -7B to ac6uire iron (or gro*th

becomes an important (actor in many in(ections1

Almost all the iron in the human body is bound to

!arious proteins eg1


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>ther Pathogen actors @ ropisms

=irulence (actors eg1 motility gro*th in al+aline p


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2pidemiology o( 7I caused by

2nterobacteriaceae

'eser!oir eg1 -I and oropharyngeal

actors controlling colonisation1

-astric p

Mikrobiologi Dasar ( Dr. Latre Buntaran,Spmk )

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