EnterobacteriaEnterobacteria

Escherichia Escherichia

SalmonellaSalmonella

Family Family EnterobacteriaceaeEnterobacteriaceae((more thanmore than 220 0 genusesgenuses, 100 , 100

speciesspecies).). The most The most

important genusesimportant genuses::  

EscherichiaEscherichia Salmonella Salmonella ShigellaShigella

CitrobacterCitrobacter EnterobacterEnterobacter HafniaHafnia KlebsiellaKlebsiella SerratiaSerratia EdwardsiellaEdwardsiella YersiniaYersinia ProteusProteus Morganella Morganella Providentia Providentia 

* Coliforms

** Noncoliforms

Diseases caused by members Diseases caused by members of the Enterobacteriaceaeof the Enterobacteriaceae

EscherichiaEscherichia – urinary tract infection, traveler’s diarrhea, – urinary tract infection, traveler’s diarrhea, neonatal meningitisneonatal meningitis

ShigellaShigella – dysentery – dysentery SalmonellaSalmonella – typhoid fever, enterocolitis – typhoid fever, enterocolitis KlebsiellaKlebsiella – pneumonia, urinary tract infection – pneumonia, urinary tract infection EnterobacterEnterobacter - pneumonia, urinary tract infection - pneumonia, urinary tract infection SerratiaSerratia - pneumonia, urinary tract infection - pneumonia, urinary tract infection ProteusProteus - urinary tract infection - urinary tract infection YersiniaYersinia – plague, enterocolitis, mesenteric adenitis – plague, enterocolitis, mesenteric adenitis

Properties of Properties of Enterobacteriaceae family Enterobacteriaceae family

membersmembers They are residents of colon, some of them inhabit They are residents of colon, some of them inhabit

respiratory tract.respiratory tract. Fecal-oral (sometimes airborn) rout of Fecal-oral (sometimes airborn) rout of

transmission.transmission. Resistant to environment factors.Resistant to environment factors. They are small, non-spore forming gram-negative They are small, non-spore forming gram-negative

rods.rods. They are facultative anaerobes They are facultative anaerobes Not fastidious to nutrient medium.Not fastidious to nutrient medium. They all ferment glucose to acid or to acid and gas.They all ferment glucose to acid or to acid and gas. Do not have proteolitic ferments Do not have proteolitic ferments None have cytochrome oxidase.None have cytochrome oxidase. Catalase-positive Catalase-positive They reduce nitrates to nitrites. They reduce nitrates to nitrites.

Morphology of enterobacteria Morphology of enterobacteria with flagellawith flagella

Morphology of enterobacteria Morphology of enterobacteria with piliwith pili

Micrograph of E.coli with Micrograph of E.coli with flagella and piliflagella and pili

Biochemical activities of E.coli and Biochemical activities of E.coli and

SalmonellaSalmonella Species Species Fermentation Fermentation

Glucose Glucose Manitol Manitol Lactose Lactose SucroseSucrose HH22SS Indole Indole

E. coliE. coli + + (ag)(ag) + (ag)+ (ag) + (ag)+ (ag) ++ -- ++

S. typhiS. typhi + (a)+ (a) + (a)+ (a) -- -- ++ --

S. S. paratyphiparatyphi

+ (ag)+ (ag) + (ag)+ (ag) -- -- ++ --

Other Other salmonellasalmonella

+ (ag)+ (ag) + (ag)+ (ag) -- -- ++ --

a – acidg - gas

Antigenic structure of Antigenic structure of enterobacteria enterobacteria

O antigen. Sometic heat-stabile polysaccharide Ag, situated in cell wall.

H antigen. Heat-labile protein Ag located in flagella. Only flagellated microorganisms, such as E.coli and Salmonella, have H Ag, whereas nonmotile ones, such as Shigella, do not.

K antigen. Heat- labile polysaccharide Ag located in capsule or in fimbria.

Modern classification of Modern classification of EscherichiaEscherichia

Family Family EnterobacteriaceaeEnterobacteriaceae

Genus Genus EscherichiaEscherichia

Species Species E.coliE.coli

Serotypes Serotypes 171 171 О-О-antigens antigens 97 К-97 К-antigens antigens 57 Н-57 Н-antigensantigens

InstanceInstance: : EE..coli Ocoli O26:K60:26:K60:HH22

Virulence factors of E.coliVirulence factors of E.coli

Pili Pili Capsule Capsule Endotoxin Endotoxin ExotoxinsExotoxins

2 enterotoxins2 enterotoxins Heat-labile toxin (LT) acts by stimulating Heat-labile toxin (LT) acts by stimulating

adenylate cyclaseadenylate cyclase Heat-stable toxin (ST) acts by stimulating Heat-stable toxin (ST) acts by stimulating

guanylate cyclaseguanylate cyclase Cytotoxin Cytotoxin

Diseases caused by E.coliDiseases caused by E.coli

Intestinal tract infectionIntestinal tract infection ( (infantile infantile

diarrhea, traveler’s diarrheadiarrhea, traveler’s diarrhea)) Systemic infectionSystemic infection::

Urinary tract infection (cystitis, uretritis)Urinary tract infection (cystitis, uretritis) Pyelonephritis Pyelonephritis Neonatal meningitisNeonatal meningitis Nosocomial (hospital-acquired sepsis)Nosocomial (hospital-acquired sepsis)

Pili

Capsule

Endotoxin

Enteropathogenic stains of Enteropathogenic stains of E.coliE.coli

EnterotoxigenicEnterotoxigenic E.coli (E.coli (О6:Н16;О6:Н16; О8:Н9;О8:Н9; О78:Н11О78:Н11 serotypes serotypes)) cause a severe diarrheal illness brought on by two cause a severe diarrheal illness brought on by two enterotoxins (HL and HS) that stimulate heightened enterotoxins (HL and HS) that stimulate heightened secretion and fluid loss (secretion and fluid loss (enterotoxins, endotoxinenterotoxins, endotoxin))

EnteroinvasiveEnteroinvasive E.coli (E.coli (О124;О124; О144;О144; О152О152 serotypes serotypes) cause ) cause an inflammatory disease similar to an inflammatory disease similar to Shigella Shigella dysenterydysentery that involves invasion and ulceration of the mucosa of that involves invasion and ulceration of the mucosa of the large intestine (the large intestine (invasioninvasion, , cytotoxin, endotoxincytotoxin, endotoxin))

EnteropathogenicEnteropathogenic E.coli (E.coli (О26:О26:KK6;6; О55:О55:KK5;5; О111: О111:KK44 ) are ) are linked to a wasting form of infantile diarrhea (linked to a wasting form of infantile diarrhea (endotoxin)endotoxin)

EnterohemorrhagicEnterohemorrhagic E.coli (E.coli (О157:Н7;О157:Н7; О126:Н11О126:Н11) causes ) causes a bloody diarrhea and hemorrhagic syndrome that can a bloody diarrhea and hemorrhagic syndrome that can cause permanent damage to the kidney (cause permanent damage to the kidney (endotoxin, endotoxin, cytotoxincytotoxin))

Treatment and Treatment and preventionprevention

Replacing the fluid loss resulting from Replacing the fluid loss resulting from vomiting and diarrheavomiting and diarrhea

Antibacterial drugs (antibiotic or Antibacterial drugs (antibiotic or sulfonamide)sulfonamide)

There is no specific prevention, such as There is no specific prevention, such as active or passive immunizationactive or passive immunization

Laboratory diagnosisLaboratory diagnosis

Bactoriologic method.Bactoriologic method. Isolation bacteria Isolation bacteria from stool by inoculation on differential medium from stool by inoculation on differential medium (MacConkey’s agar). E.coli which ferments (MacConkey’s agar). E.coli which ferments lactose, forms pink colonies, whereas lactose-lactose, forms pink colonies, whereas lactose-negative microorganisms are colorless.negative microorganisms are colorless.

Important features that help to distinguish E.coli Important features that help to distinguish E.coli from other from other lactose-fermenting gram-negative lactose-fermenting gram-negative rodsrods are as: are as:indole productionindole productionnonproduction of Hnonproduction of H22SSit is motileit is motilefermentation of lactose to acid and gasfermentation of lactose to acid and gasantigen structureantigen structure

Disease caused by Disease caused by SalmonellaSalmonella

Typhoid feverTyphoid fever is caused by S.typhiis caused by S.typhi

EnterocolitisEnterocolitis is caused by S.paratyphi A, B, C, is caused by S.paratyphi A, B, C, S.typhimuriumS.typhimurium

Salmonella food poisoningSalmonella food poisoning ( (different different

species of Salmonellaspecies of Salmonella)) Septicemia Septicemia is most often caused by is most often caused by

S.cholerae-suisS.cholerae-suis

Modern classification of Modern classification of Salmonella (by Ewing)Salmonella (by Ewing)

The genus Salmonella is divided into The genus Salmonella is divided into 3 species:3 species:

S.typhi (S.typhi (1 serotype1 serotype)) S.cholerae-suis (S.cholerae-suis (1 serotype, causes zoonosis of 1 serotype, causes zoonosis of

swineswine)) S.enteritidis (S.enteritidis (approximately 1700 serotypesapproximately 1700 serotypes))

Antigenic structure of Antigenic structure of SalmonellaSalmonella

O antigen O antigen The H antigen of certain Salmonella species are The H antigen of certain Salmonella species are

unusual because the microorganisms can unusual because the microorganisms can reversibly alternate between 2 types of H Ag reversibly alternate between 2 types of H Ag called phase 1 and phase 2. called phase 1 and phase 2.

In S.typhi K antigen is called the Vi antigen (Vi In S.typhi K antigen is called the Vi antigen (Vi being the being the vivirulence or capsule Ag.)rulence or capsule Ag.)

Kaufman – White Kaufman – White classification of Salmonellaclassification of Salmonella (1934) (1934)

Serogroup (or Serogroup (or species)species)

O antigen O antigen H antigen H antigen

Phase Phase 1 1 Phase Phase 2 2

SerogroupSerogroup А АS. paratyphi AS. paratyphi A 1, 2, 121, 2, 12

  AA

   (1,5) (1,5)

SerogroupSerogroup BBS. schottmuelleriS. schottmuelleriS. typhimuriumS. typhimuriumS. heidelbergS. heidelberg

1, 4, (5), 121, 4, (5), 12 1, 4, (5), 121, 4, (5), 12 1, 4, (5), 121, 4, (5), 12

BBiiRR

1,21,21,21,21,21,2

SerogroupSerogroup CCSS. . choleraesuischoleraesuisS. montevideoS. montevideo

6, 76, 7 6, 76, 7

( c )( c ) m, s, (p)m, s, (p)

1,51,5 --

SerogroupSerogroup DDSS. . typhityphiS. enteritidisS. enteritidis

9,129,12 1,9,121,9,12

DDg, mg, m

--(1,7)(1,7)

Modern classification of Modern classification of SalmonellaSalmonella

Salmonella

Species S. bongori

(10 serotypes) – all salmonellae parasite in cold-blood animals

Species S. enterica

(6 subspecies, > 2000 serotypes – all are agents of diseases in warm-blood animals and human)

Stage of pathogenesis of Stage of pathogenesis of typhoid fevertyphoid fever

Digestive.Digestive. The typhoid bacillus usually enters the alimentary The typhoid bacillus usually enters the alimentary canal along with water or food contaminated by feces.canal along with water or food contaminated by feces.

Invasive.Invasive. Bacteria penetrate in lymphoid system of small Bacteria penetrate in lymphoid system of small intestine (Peyer’s patches, mesenteric lymph nods) and reproduce intestine (Peyer’s patches, mesenteric lymph nods) and reproduce in these cells. in these cells.

BacteremiaBacteremia. . With infected phagocytes bacteria get to the With infected phagocytes bacteria get to the bloodstream where they are destructed, release endotoxin and bloodstream where they are destructed, release endotoxin and cause toxemia. Since this stage manifestation begins. cause toxemia. Since this stage manifestation begins.

Parenchymal diffusion. Parenchymal diffusion. Bacteria with blood and infected Bacteria with blood and infected cells spread to the liver, gallbladder, spleen, bone marrow, where cells spread to the liver, gallbladder, spleen, bone marrow, where father multiplication takes place. father multiplication takes place.

Excretive-allergic. Excretive-allergic. S.typhy again get to the enterocytes S.typhy again get to the enterocytes where induces allergy reaction that lead to intestinal rupture and where induces allergy reaction that lead to intestinal rupture and hemorrahage. Bacteria in great amount excrete from the organism hemorrahage. Bacteria in great amount excrete from the organism with feces and urine. with feces and urine.

Immunity formation Immunity formation End of diseaseEnd of disease ( (death, complete convalescence or death, complete convalescence or

transformation in bacteria carringtransformation in bacteria carring))

Damage of intestinal wall Damage of intestinal wall (excretive-allergic stage of typhoid (excretive-allergic stage of typhoid

fever)fever)

Perforations Ulcers

Laboratory diagnosis of Laboratory diagnosis of typhoid fever typhoid fever

Time of Time of investigationinvestigation

Method Method Material from the Material from the patientpatient

Since 1Since 1stst week week to end of to end of disease disease (bacteremia)(bacteremia)

Bacteriological. Bacteriological. Blood Blood

Since 2Since 2stst week week to end of to end of diseasedisease

Bacteriological. Bacteriological. Urine, feces, bile, bone Urine, feces, bile, bone marrowmarrow

Serological Serological (indication of rise (indication of rise antibody to antibody to agent)agent)

Serum Serum

Treatment and prevention Treatment and prevention

Treatment.Treatment. AntibioticsAntibiotics

Specific prophylaxis.Specific prophylaxis. There are 2 There are 2 vaccine:vaccine: Inactivated vaccine from acetone-killed S.typhi Inactivated vaccine from acetone-killed S.typhi

organismsorganisms Live oral vaccine from attenuated S.typhiLive oral vaccine from attenuated S.typhi