ENTEROBACTERIACEAEENTEROBACTERIACEAE

Dr. Abdulaziz AlkhattafDr. Abdulaziz Alkhattaf

coliformscoliforms Non-spore forming, gram negative bacilli.Non-spore forming, gram negative bacilli.

Facultative anaerobic.Facultative anaerobic.

Catalase +ve; Oxidase Catalase +ve; Oxidase ––ve.ve.

Motility ±; some are capsulatedMotility ±; some are capsulated..

Widely dispersed in nature, yet was found Widely dispersed in nature, yet was found

to inhabit the intestine of mammalians.to inhabit the intestine of mammalians.

Grow well in ordinary media (blood agar, Grow well in ordinary media (blood agar,

Mc-conkey agar) aerobically or facultative Mc-conkey agar) aerobically or facultative

anaerobic.anaerobic.

IdentificationIdentification1.1. Lactose fermentation:Lactose fermentation: McConkey agar contains lactose and McConkey agar contains lactose and

pH indicator + pink colonies.pH indicator + pink colonies. CLED agar changes from blue-green to CLED agar changes from blue-green to

yellow colonies.yellow colonies.

2.2. Biochemical tests:Biochemical tests:

(a)- Reduce nitrate to nitrite.(a)- Reduce nitrate to nitrite.

(b)- Ferment glucose with acid (b)- Ferment glucose with acid (sometimes gas production).(sometimes gas production).

(c)- The use of API 20E biochemical kit (c)- The use of API 20E biochemical kit tests.tests.

Identification tools used in the labIdentification tools used in the lab

Identification of coliformsIdentification of coliforms3.3. Serological tests:Serological tests:

Based on the somatic (O) antigen and the Based on the somatic (O) antigen and the

flagellar antigen (H) for the identification of flagellar antigen (H) for the identification of

Salmonella and Shigella species.Salmonella and Shigella species.

4.4. Bacteriophage typing (using viruses to Bacteriophage typing (using viruses to

identify bacteria).identify bacteria).

5.5. Bacteriocine typing (pigments produced by Bacteriocine typing (pigments produced by

bacteria).bacteria).

6.6. Plasmid analysis (extra-chromosomal DNA).Plasmid analysis (extra-chromosomal DNA).

7.7. Polypeptide analysis (polyacrylamide gel Polypeptide analysis (polyacrylamide gel

electrophoresiselectrophoresis).).

Antigenic structureAntigenic structure

Enterobacteria Enterobacteria

possess variety of possess variety of

heterogeneous heterogeneous

antigens:antigens:

Somatic/cell wall Somatic/cell wall

(O)(O)

Flagella (H)Flagella (H)

Capsular (K)Capsular (K)

PathogenicityPathogenicity

1.1. Virulence FactorsVirulence Factors::

i.i. Endotoxin: LipopolysaccharideEndotoxin: Lipopolysaccharide

Lipid A: toxinLipid A: toxin

Polysaccharide: antigenicPolysaccharide: antigenic

ii.ii. Capsule Capsule –– antiphagocytic. antiphagocytic.

iii.iii. Pili -for attachment ( K88 of Pili -for attachment ( K88 of

E.coliE.coli→dirrhoea/infant pigs)→dirrhoea/infant pigs)

iv.iv. Enterotoxins→ e.g Enterotoxins→ e.g E.coliE.coli causing diarrhoea. causing diarrhoea.

PathogenicityPathogenicity2.2. Diseases:Diseases:i.i. Intestinal Intestinal Salmonella Salmonella }} PrimaryPrimary ShigellaShigella } } intestinal intestinal

Pathogens.Pathogens. E.coliE.coli:: some strains are some strains are

intestinal intestinal

Pathogens.Pathogens.

ii.ii. Extra-intestinalExtra-intestinal

UTI UTI ––Coliforms contribute up to 80% UTI.Coliforms contribute up to 80% UTI.

Wound infections/ post operative.Wound infections/ post operative.

Respiratory tract infection.Respiratory tract infection.

Septicaemia.Septicaemia.

MeningitisMeningitis→→neonates (E.coli) /or with trauma neonates (E.coli) /or with trauma

/surgery/surgery

Antibiotic sensitivityAntibiotic sensitivity

i.i. Enterobacteria are resistant to multiple Enterobacteria are resistant to multiple antibiotics.antibiotics.

ii.ii. In vitro sensitivity testing is required to In vitro sensitivity testing is required to monitor the trend and to assess based monitor the trend and to assess based on case by case.on case by case.

iii.iii. The most common antibiotic used areThe most common antibiotic used are:: Ampicillin/ amoxycillin and mezlocillin.Ampicillin/ amoxycillin and mezlocillin. Aminoglycosides.Aminoglycosides. Trimethoprim.Trimethoprim. Chloramphenicol.Chloramphenicol. Ciprofloxacin.Ciprofloxacin. Cephalosporins (2nd,3rd generations)Cephalosporins (2nd,3rd generations) Nitrofurantoin, Nalidixic acid/ UTI only.Nitrofurantoin, Nalidixic acid/ UTI only.

Escherichia coliEscherichia coli

Serology of Serology of E.coliE.coli::

According to the cell wall (O antigen) over According to the cell wall (O antigen) over

160 types recognized.160 types recognized.

According to the flagellar (H antigen) 55 According to the flagellar (H antigen) 55

types.types.

Making over 8000 possible O-H seotypes.Making over 8000 possible O-H seotypes.

Some Some E.coliE.coli types are capsulated types are capsulated

Pathogenicity of E.coliPathogenicity of E.coli i.i. IntestinalIntestinal::

TermTerm AbbreviAbbreviationation

Pathogenic Pathogenic PhenotypePhenotype

Signs&Signs&Symptoms Symptoms

EnterotoxigenEnterotoxigenic ic E.coliE.coli

ETECETEC Secretion of:Secretion of:heat-Labile heat-Labile

(LT)/(LT)/heat-stable heat-stable

(ST(ST)/)/

TravelerTraveler’’s diarrhoeas diarrhoeaWatery, mild abdominal Watery, mild abdominal cramp ,(small intestine) cramp ,(small intestine) dehydration,vomitingdehydration,vomiting

EnteroaggregEnteroaggreg

ative Eative E.coli.coli EaggECEaggEC Adhere to Adhere to

epith.cellsepith.cells Watery diarrhoea, Watery diarrhoea,

vomit, dehydration, vomit, dehydration, abdominal painabdominal pain

EnteropathogEnteropathogenic enic E.coliE.coli

EPEC EPEC Adhere to Adhere to epithelial cells epithelial cells (pilli)/effacing (pilli)/effacing

lesions lesions

Infants (18-24month); Infants (18-24month); low low

fever,malaise,vomiting, fever,malaise,vomiting, diarrhoea→ (duodenum)diarrhoea→ (duodenum)

EnteroinvasivEnteroinvasive e E.coliE.coli

EIECEIEC Invade colonic Invade colonic mucosa ;Causimucosa ;Causing dysenteric-ng dysenteric-like diarrhoealike diarrhoea

Dysentery;fever, Dysentery;fever, colitis,diarrhoea with colitis,diarrhoea with

blood, mucus, blood, mucus, LeukocytesLeukocytes

EnterohaemorEnterohaemorrhagic rhagic E.coliE.coli EHECEHEC Production of Production of

cytotoxin cytotoxin serotype serotype 0157;H70157;H7

Bloody diarrhoea,WBCs, Bloody diarrhoea,WBCs, →Haemorrhagic.colitis →Haemorrhagic.colitis &Haemolytic uraemic &Haemolytic uraemic

syndrome (HUS)/Acute syndrome (HUS)/Acute renal failurerenal failure

Pathogenicity of E.coliPathogenicity of E.coli

2.2. Extra-intestinalExtra-intestinal

i.i. Urinary tract infection (UTI)/ Urinary tract infection (UTI)/ causes causes 80% of UTI in pregnant females80% of UTI in pregnant females..

ii.ii. Wound infection/ Surgery of lower Wound infection/ Surgery of lower

intestinal tract.intestinal tract.

iii.iii. Peritonitis.Peritonitis.

iv.iv. Septicemia.Septicemia.

v.v. Neonatal meningitis. Neonatal meningitis.

KLEBSIELLA l KLEBSIELLA l ENTEROBACTER/ ENTEROBACTER/ SERRATIASERRATIA

Widely spread in the environment/ in the intestine Widely spread in the environment/ in the intestine

flora offlora of

man and animals.man and animals.

Survive well in moist environments in hospitals.Survive well in moist environments in hospitals.

Opportunistic pathogens → chances of infection Opportunistic pathogens → chances of infection

are increased in long term hospitalization, ICU.are increased in long term hospitalization, ICU.

Grow well on all media /producing large and Grow well on all media /producing large and

mucoid colonies (capsule).mucoid colonies (capsule).

Β-lactamases producing/ resistant to ampicillin,1st Β-lactamases producing/ resistant to ampicillin,1st

and 2nd generation of cephalosporins→ therefore and 2nd generation of cephalosporins→ therefore

we resort to using we resort to using AAminoglycosidesminoglycosides..

PathogenicityPathogenicity

1.1. Urinary tract infection (chronic, Urinary tract infection (chronic,

complicated infections).complicated infections).

2.2. Wounds, skin lesions and respiratory Wounds, skin lesions and respiratory

infections in hospitalised patients.infections in hospitalised patients.

3.3. Septicemia.Septicemia.

4.4. Abscesses, endocarditis, chronic nasal and Abscesses, endocarditis, chronic nasal and

oropharyngeal sepsis.oropharyngeal sepsis.

5.5. Meningitis (neonates).Meningitis (neonates).

PROTEUS /MORGANELLA / PROVIDENCIAPROTEUS /MORGANELLA / PROVIDENCIA

HabitatHabitat: : Human and animal intestine//soil/ Human and animal intestine//soil/

water.water.

Isolation: Grow well on ordinary media in a Isolation: Grow well on ordinary media in a

swarming type, which cover the plate.swarming type, which cover the plate.

IdentificationIdentification: Swarming, and all species : Swarming, and all species

produce a potent produce a potent urease enzymeurease enzyme..

phage, bacteriocine and serotyping phage, bacteriocine and serotyping

schemes have been developed for schemes have been developed for

identification there species.identification there species.

PathogenesisPathogenesis

Urinary tract infection / urea is split by the Urinary tract infection / urea is split by the

Proteus urease to produce ammonia→alkaline Proteus urease to produce ammonia→alkaline

urinary pH.urinary pH.

Urease-producing organisms (proteus) may Urease-producing organisms (proteus) may

provoke the formation of provoke the formation of calculi (stones) calculi (stones) in in

urinary tract.urinary tract.

Ear ,wound and burn infections (mixed Ear ,wound and burn infections (mixed

infection).infection).

Septicaemia and brain abcesses. Septicaemia and brain abcesses.

PSEUDOMONASPSEUDOMONAS Gram Negative Bacilli; non-fermentative Gram Negative Bacilli; non-fermentative strictly strictly

aerobicaerobic, motile and oxidase positive., motile and oxidase positive. Pseudomonas species commonly inhibit soil, Pseudomonas species commonly inhibit soil,

water and are widely spread. Can use variety of water and are widely spread. Can use variety of carbon and nitrogen sources.carbon and nitrogen sources.

Difficult to eradicate / especially in hospital Difficult to eradicate / especially in hospital wards, operating theatres and medical wards, operating theatres and medical equipments (respiratory ventilators) being equipments (respiratory ventilators) being resistant to many disinfectants.resistant to many disinfectants.

clinical isolates produce a characteristic green clinical isolates produce a characteristic green or blue-green pigment called or blue-green pigment called PyocyaninPyocyanin. Also . Also produce produce Pyoverdin Pyoverdin (fluorescein) a yellow-(fluorescein) a yellow-green pigment↔fluoresces under UV light .green pigment↔fluoresces under UV light .

PathogenesisPathogenesis Ps.aeruginosa is an important opportunistic Ps.aeruginosa is an important opportunistic

pathogen.pathogen. causing infection in immunocompromised patients / causing infection in immunocompromised patients /

burns, HIV,cancer and cystic fibrosis patients. burns, HIV,cancer and cystic fibrosis patients. pseudomonas enters blood stream causing sepsis pseudomonas enters blood stream causing sepsis

with 50% mortality rate.with 50% mortality rate. spread to skin causing black necrotic lesions spread to skin causing black necrotic lesions

(ecthyma gangrenosum).(ecthyma gangrenosum). Severe external otitis (malignant otitis externa).Severe external otitis (malignant otitis externa). other skin lesions (folliculitis)↔ inadequate other skin lesions (folliculitis)↔ inadequate

chlorinated swimming pool users.chlorinated swimming pool users. Corneal infections↔ contact lens users. Corneal infections↔ contact lens users.

TreatmentTreatment

Psedomonas is resistant to many antibiotics /e.g penicillin, Psedomonas is resistant to many antibiotics /e.g penicillin,

ampicillin, tetracycline, most cephalosporins.ampicillin, tetracycline, most cephalosporins.

Psedomonas infections were usually treated with Psedomonas infections were usually treated with

polymyxins, now stopped for its high toxicity.polymyxins, now stopped for its high toxicity.

Antipseudomonal Antipseudomonal ββ-lactam compounds such as zlocillin, -lactam compounds such as zlocillin,

ticarcillin, imipenem and ceftazidime are commonly used.ticarcillin, imipenem and ceftazidime are commonly used.

Aminoglycosides such as gentamicin and tobramycin are Aminoglycosides such as gentamicin and tobramycin are

also used and some times with combination also used and some times with combination ββ-lactams.-lactams.

Fluoroquinolones (ciprofloxacin) can be given orally.Fluoroquinolones (ciprofloxacin) can be given orally.

EpidemiologyEpidemiology Species have theSpecies have the ability to multiply on moist equipments ability to multiply on moist equipments

(humidifiers) in hospital wards, bathrooms& kitchens.(humidifiers) in hospital wards, bathrooms& kitchens.

Resistant to many disinfectants and antiseptics.Resistant to many disinfectants and antiseptics.

Can contaminate pharmaceutical preparations and may Can contaminate pharmaceutical preparations and may

cause ophthalmitis to contact lenses users.cause ophthalmitis to contact lenses users.

Important cause of Important cause of nosocomial infectionsnosocomial infections 10-30% of 10-30% of

hospital-acquired infections. hospital-acquired infections.

Airborne pseudomonas is hazardous to burned and ICU Airborne pseudomonas is hazardous to burned and ICU

patients.patients.

Ear infection and irritating folliculitis (jacuzzi rash) occur Ear infection and irritating folliculitis (jacuzzi rash) occur

due to poorly maintained swimming pools or jacuzzis. due to poorly maintained swimming pools or jacuzzis.

Pseudomonal controlPseudomonal control

Prevention is easier than cure:Prevention is easier than cure:

1.1. Immunocompromised and patient with high risk Immunocompromised and patient with high risk

of acquiring Ps. aeruginosa should not be of acquiring Ps. aeruginosa should not be

admitted to a ward with cases of such infection admitted to a ward with cases of such infection

are present.are present.

2.2. Therapeutic substances must be free from Ps Therapeutic substances must be free from Ps

especially multi-dose ointments, creams or eye especially multi-dose ointments, creams or eye

drops.drops.

3.3. Using typing system to identify cross-infection of Using typing system to identify cross-infection of

one strain (epidemic strains).one strain (epidemic strains).

AcinetobacterAcinetobacter

Gram negative coccobacilli resemble Gram negative coccobacilli resemble Enterobacteriaceae in growth pattern Enterobacteriaceae in growth pattern and colonial morphology.and colonial morphology.

Incapable of fermenting carbohydrates Incapable of fermenting carbohydrates or reduce nitrates.or reduce nitrates.

Appear frequently as skin and Appear frequently as skin and respiratory colonizers.respiratory colonizers.

Frequently contaminate wet objects Frequently contaminate wet objects including soaps and disinfectant including soaps and disinfectant solutions.solutions.

Pneumonia, urinary tract Pneumonia, urinary tract andand soft soft tissue tissue are the most common infectionsare the most common infections

Nosocomial respiratory infections are Nosocomial respiratory infections are traced to contaminated inhalation traced to contaminated inhalation therapy equipments whereas therapy equipments whereas bacteremia to infected intravenous bacteremia to infected intravenous catheters.catheters.

Due to frequent resistance to Due to frequent resistance to penicillins, cephalosprins and some penicillins, cephalosprins and some aminoglycosides treatment is difficult aminoglycosides treatment is difficult and required prior sensitivity testing.and required prior sensitivity testing.

  

MoraxellaMoraxella

Gram negative coccobacilli in pairs.Gram negative coccobacilli in pairs. Fastidious growth (required enriched Fastidious growth (required enriched

media-chocolate agar).media-chocolate agar). Due to similarity in morphology and Due to similarity in morphology and

positive oxidase reaction positive oxidase reaction MoraxellaMoraxella is is some times confused with some times confused with NeisseriaNeisseria. .

Causes Causes otitis media, sinusitis otitis media, sinusitis andand lower respiratory infection. lower respiratory infection.

Burkholderia pseudomalleiBurkholderia pseudomallei

Free living saprophyte that causes Free living saprophyte that causes

melioidosismelioidosis,, a devastating tropical a devastating tropical

infection of animal and humans that is infection of animal and humans that is

endemic in eastern Asia and north endemic in eastern Asia and north

Australia.Australia.

Laboratory-acquired infection is a serious Laboratory-acquired infection is a serious

risk; the species is included in hazard risk; the species is included in hazard

group 3 (together with plague).group 3 (together with plague).

Melioidosis:Melioidosis:

Human infection is mainly acquired Human infection is mainly acquired

cutaneously through skin abrasions or by cutaneously through skin abrasions or by

inhalation of contaminated particles.inhalation of contaminated particles. Clinical manifestation range from a sub-Clinical manifestation range from a sub-

clinical infection, diagnosed by the clinical infection, diagnosed by the presence of specific antibodies, to a presence of specific antibodies, to a benign pulmonary infection that may benign pulmonary infection that may resemble tuberculosis or septicemia with resemble tuberculosis or septicemia with mortality rate of 80-90%.mortality rate of 80-90%.

In north eastern Thailand, In north eastern Thailand, B.pseudomallie B.pseudomallie is responsible for 20% of all community is responsible for 20% of all community acquired septicemia.acquired septicemia.

Early diagnosis and appropriate Early diagnosis and appropriate

antibiotic therapy are key factors in the antibiotic therapy are key factors in the

successful management of melioidosis.successful management of melioidosis.

Organism may be isolated from sputum, Organism may be isolated from sputum,

urine, pus or blood (gram –ve bacilli).urine, pus or blood (gram –ve bacilli).

ELISA is used for detection of IgG anf IgM ELISA is used for detection of IgG anf IgM

antibodiy to antibodiy to B.pseudomallieB.pseudomallie as well as as well as

indirect haemagglutination test.indirect haemagglutination test.

TreatmentTreatment Combination of tetracycline and chloramphenicol Combination of tetracycline and chloramphenicol

for long period of time, have been widely used.for long period of time, have been widely used.

The ability of The ability of B.pseudomallieB.pseudomallie to survive and to survive and

multiply in phagocytic macrophages may explain multiply in phagocytic macrophages may explain

the difficulty to treat the disease.the difficulty to treat the disease.

Antibiotics that are effective against the Antibiotics that are effective against the

organism in vitro are not successful in vivo organism in vitro are not successful in vivo

unless with prolong period of treatment.unless with prolong period of treatment.

Ceftazidime is both effective in vitro and in vivo.Ceftazidime is both effective in vitro and in vivo.

Burkholderia cepaciaBurkholderia cepacia Major opportunistic cause of respiratory Major opportunistic cause of respiratory

infection in patients with chronic infection in patients with chronic granulomatous (cystic fibrosis) disease.granulomatous (cystic fibrosis) disease.

The organism is multi-resistance to many The organism is multi-resistance to many antibiotics and transport by social contact.antibiotics and transport by social contact.

Cepacia syndrome, an acute fatal necrotizing Cepacia syndrome, an acute fatal necrotizing pneumonia, some times accompanied by pneumonia, some times accompanied by bacteraemia is a risk with bacteraemia is a risk with B.cepacia.B.cepacia.

For treatment of For treatment of B.cepaciaB.cepacia ceftazidime or ceftazidime or cabapenem, meropenem.cabapenem, meropenem.

Eikenella corrodensEikenella corrodens

Commensal of mucosal surface may Commensal of mucosal surface may

cause range of infections such as cause range of infections such as

endocarditis, meningitis, pneumonia endocarditis, meningitis, pneumonia

and infections of wounds and various and infections of wounds and various

soft tissues.soft tissues.

Flavobacterium meningosepticumFlavobacterium meningosepticum

Meningitis with Meningitis with F.meningosepticumF.meningosepticum is is

responsible for high mortality in responsible for high mortality in

epidemic outbreaks.epidemic outbreaks.

Is a saprophyte that could cause Is a saprophyte that could cause

opportunistic nosocomial infections in opportunistic nosocomial infections in

infants.infants.