bacterial urinary infections

8/19/2019 Bacterial Urinary Infections

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BACTERIAL INFECTIONS

OF URINARY RTACT

ByDr. Marwa Salah


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Learning objectives1. List names, major structural features, pathogenic

mechanisms, clinical signi cance & laboratory diagnosisof the main bacteria that cause urinary tract infection.

2. Outline structure, pathogenesis, clinical signi cance andlaboratory diagnosis of the following bacteria asuropathogens:

• Escherichia coli• Klebsiella pneumonia• Staphylococcus saprophyticus• Proteus mirabilis• Serratia marcescens• Enterococcus faecalis

. !escribe structure, pathogenesis, clinical signi cance &laboratory diagnosis of Pseudomonas aeruginosa asuropathogen

References• Monica Cheesbrough, District laboratory practice in tropical

countries, part 2, 2 nd edition, 2006• Ja et!, Melnic" # $delburg, Medical %icrobiology, 2& th ed', 20(0• )ayser,Medical Microbiology, 200&


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BACTERIAL INFECTIONS OF URINARYRTACT

*acteria Majorstructuralfeatures

pathogenesis

Clinicalsigni+cance

Labdiagnosis

Escherichi a coli

-ve%otilebacilli

$dhesins.ae%olysin

s) antigen

/ 1 •M 3•4uantitativeurine culture

Klebsiella pneumoni a

-venon5%otilebacilli

Capsule / 1 •M 3•4uantitativeurine culture

Proteusmirabilis

-ve%otilebacilli

$dherence/reaseMotility

/ 1 •M 3•4uantitativeurine culture

Serratia 5ve $dherence / 1 •M 3


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ther bacteria that %ay cause / 1• S aureus• ther coagulase negative staphylococci• B fragilis• M tuberculosis

7redisposing factors of / 1• 8hort fe%ale urethra• 8e9ual intercourse• 8enile prostatic hypertrophy• 8tructural # neurological abnor%alities of

/ hich are associated ith residualurine :inco%plete e%ptying of bladder;

• Catheteri!ation• .ost factors as DM # i%%unosuppression


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Escherichia coli


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Anti%enic st'(ct('eSerological classification of E. coli is based on:

!" O /somatic1 anti%en of the cell wall lipopolysaccharide(LPS)

2" / la%ella'1 anti%en3. Capsular (K) antigen in capsulated strains


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atho%enesis• 0ost +'e$ominant ac(ltati&e anae'o8e in la'%e intestine o man• 'o&i$es +'otection a%ainst ha'm (l mic'oo'%anisms• One o the im+o'tant in$icato's o aecal +oll(tion o *ate'9since it is constantl. o(n$ in h(man ) animal aeces /8esi$es E.

faecalis ) Cl. Perfringens 1

i'(lence Facto's o ('o+atho%enic st'ains!"U'o+atho%enic st'ains ha e im8'ial a$hesins, e#oto#ins

/haemol.sins1 an$ : anti%en2"L S causes endoto!ic shoc"

;iseases Ca(se$ 8. E. coli !"U'ina'. t'act in ection /UTI12"Neonatal menin%itis" +ne(monia, se+sis, se+ticaemia )en$oto#ic shoc5

3";ia''hoea by diarrhaeogenic strains


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U'ina'. T'act In ection /UTI1Comm(nit. ac


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La8o'ato'. ;ia%nosisA" S+ecimen ('ine

U'ine Sam+le collection

B" ;i'ect $etection0ic'osco+.

=et mo(nt +(s cells, motilit. test

>'am staine$ smea'


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C" C(lt('eU'ine should be uantitati ely

cultured to deter,ine si%ni icant8acte'('ia /!? @ CFU ml1

;" I$enti ication!" Colon. mo'+holo%.2" >'am stain3" O#i$ase test4" Biochemical 'eactions

In vitro s(sce+ti8ilit. to anti8iotics/ because of e,ergence of resistantstrains)


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KLEBSIELLA


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•Ente'o8acte'iacaea•Im+o'tant mem8e's a'e K. ne!"oniae ,

K. o#aenae , K. r$inosclero"atis ) K. o%&toca / K " ne!"oniae is the me$icall. mostim+o'tant s+ecies1

0o'+holo%. >'am ne%ati&e 8acilli, non motile,ca+s(late$ /ca+s(le is the most im+o'tant&i'(lence acto'1

C(lt('e•


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Biochemical Reactions:le8siella e'ments s(%a's *ith +'o$(ction

o aci$ ) %asI0 C is --

atho%enesis•ha8itats /!1 the en&i'onment in s(' ace *ate', se*a%e, soil) on +lants /21 m(cosal s(' aces o intestinal ) 'es+i'ato'.

t'acts

• 0(lti $'(% 'esistant Kle'siella st'ains ma.+'e&ail in hos+itals ) ca(se se'io(s

nosocomial in ections


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;iseases /Comm(nit. o' os+ital ac


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La8o'ato'. ;ia%nosisA"S+ecimens ('ine

B" ;i'ect $etection0ic'osco+.

=et mo(nt +(s cells, motilit. test>'am staine$ smea'

C" C(lt('e ) I$enti ication /similar to E. coli)

U'ine co(nt

In vitro s(sce+ti8ilit. to anti8iotics


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Proteus mirabilis


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• 1%portant species include Pr ' mirabilis ,Pr ' Vulgaris

• Providencia rettgeri # M ' morganii areclassi+ed as ne genera

Morphology• ra%5negative bacilli, %otile,

usually pleo%orphic

Cultural characters•


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*ioche%ical reactions•Lactose non5fer%enter :L


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Serratia "arcescence


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3nterobacteriacaeaMorphology

5ve bacilli

Culture8o%e strains produce red pig%ent # are used fortesting eGciency of bacterial +lters

7athogenesis # clinical signi+cance"


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PSEUDOMON S E!U"#NOS


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MorphologyG –ve motile bacilli

Cultural characters•Aerobic, 24h, ! oC "ca# growi# 42 oC$•Simple me%ia& #utrie#tagar' gree#ish e(opigme#t

"yellow pyover%i#)bluepyocya#i#$, grape*li+e o%our •Some are *haemolytic

•MacCo#+ey agar& - /


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*ioce%ical reactions• on5fer%entative :acid is

produced fro% glucose onlyo9idatively;

• 9idase ve

7seudo%onas is not an7seudo%onas is not an3ntrobacteriacaea as it is3ntrobacteriacaea as it isaerobic, non5fer%entative #aerobic, non5fer%entative #o9idase veo9idase ve


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7athogenicity• Forld ide, part of nor%al Hora• ro s in %oist environ%ents• .ighly resistant to antibiotics # disinfectants• 1n hospitals :nosoco%ial infection;• 8igni+cant hu%an pathogen particularly in

i%%unoco%pro%ised

• Eirulence factors@ invasive, to9igenic # pyogenic('7ili@ attach%ent2'L78@ endoto9in='3n!y%es@ elastase, protease, t o hae%olysins?'39oto9in $@ tissue necrosis


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Co%%unity5acIuired

infections•


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$' 8peci%en@ urine

*' Direct detection

C' Culture@

D' 1denti+cation@('Colony %orphology

2' ra% stain=' 9idase test # other

bioche%ical reactions?'7hage # pyocin typing for

epide%iological purposes#n vitro susceptibility to

antibiotics


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Staph$lococcussaproph$ticus


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• #oagulase $%e staphylococci

• annitol fermentation is%ariable, usually fermenter onmannitol'salt agar

• (on'haemolytic on blood agar

• !i)erentiated from Sepidermidis in beingno%obiocin resistant

• *econd to E coli as a cause of+ - in se ually acti%e youngfemale


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Enterococcus faecalis


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• E faecalis causes /0' 3 ofenterococcal infections, E faecium causes 0'1 3

Morphology• 4ram 5%e cocci, single, pairs or

short chains

Cultural characters• 67, can grow in 1 '80 o#• 4row in broth containing 9.0 3

(a#l• (on'haemolytic, occasionally

alpha'haemolytic• L6 on ac#on ey

E faecalis in NaCl 6.5%

S pyogenes in NaCl 6.5%


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*ioche%ical reactions• .ydrolyse esculin in presence of

bile salts

• Catalase -ve• 7 R ve

$ntigenic structure• Most strains react ith Lance+eldgroup D antibodies

7athogenesis7art of nor%al intestinal Hora$ntibiotic resistant@ resistant to

penicillin # vanco%ycin, K5lacta%ase production


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Clinical diseases.ospital acIuired rather than co%%unity

acIuired :particularly in 1C/;• /rinary tract infection@ the %ost

co%%on• 1ntra5abdo%inal or pelvic ound

infection• *actere%ia, endocarditis, %eningitis,

peritonitis, osteo%yelitis, abscesses,

ound infection

bacterial urinary infections

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