bacterial urinary infections
TRANSCRIPT
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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