Enterobacteriaceae - Microbiology Lecture Notes PDF

ENTRO BACTERIACEAE Dr. NAWAID HUSSAIN KHAN, Ph.D. ASSISTANT PROFESSOR MICROBIOLOGY ALA-TOO INTERNATIONAL UNIVERSITY  Common Features of Family Most of them are Non-pathogenic/no...

ENTRO BACTERIACEAE Dr. NAWAID HUSSAIN KHAN, Ph.D. ASSISTANT PROFESSOR MICROBIOLOGY ALA-TOO INTERNATIONAL UNIVERSITY  Common Features of Family Most of them are Non-pathogenic/no Normally All members rmal flora, several member's are are living or They all look are beneficial, and found in-soil, associated with alike in gram few are pathogenic water, Gastrointestinal stain smear- and contaminant Tract (GIT)/ GNB. opportunistic(Clini food, Intestinal Enteric bacilli/ cally significant) tract of human Coli form associated with and animals human diseases.  Common Features of Family Associated Due to with 50% of severity of various clinical infection human significant 80% of caused by diseases- bacteria clinical these family GIT isolated 50% of significant 70% of UTI members infection, from all Septicemia isolated of prompt UTI, Wound clinical GNB Isolation, and sample in Identificatio Respiratory bacteriologi n and AST tract cal Lab are essential infections  Family Member's Escherichia coli (E.coli) Klebsiella Lactose-Fermenting Enterobacter Citrobacter Serratia Pantoea Salmonella Shigella(one Sp is LLF) Non-Lactose-Fermenting Proteus Morganella morganii Providencia Yersinia Escherichia coli (E.coli)  E.coli Species GNB, Motile by peritrichous flagella, Nonsporing E.coli Non-capsulated /few stain capsulated, pili(fimbriae) E.Fergusonii Size-1-3u×0.4-0.7u E.Hermanii Present in GUT-Normal flora, Endogenous source of infection. E.Vuneris E. coli is very commonly isolated from E.Blatae clinical specimens. is the most commonly isolated member of the Enterobacteriaceae family.  Identification-culture &Colony character Nutrient agar: Temp range- MacConkey Aerobe & Can be grow large,2- Blood agar: 10- ’s agar: Pink facultative on nutrient 3mm,circular Beta- 40°c(optima flat-due to anaerobe ager ,opaque,gray haemolytic l-37°c) LF white colonies  Identification-Biochemical Voges- Methyl red Triple sugar Indol (I)= Proskaur Citrate (C) Urease = H2S IMViC test (MR)= iron(TSI) = Positive (VP)= = Negative Negative =Negative Positive Acid & Gas Negative  Antigenic diversity Type Antigen Variation H -Ag Flagellar 75 H Ags O -Ag Somatic 173 O Ags K -Ag Capsular 103 Ags F -Ag Fimbria/Pili K - Ag a strong associated F-Ag associated with UTI O-Ag due to LPS with virulence particularly Meningitis, Pyelonephritis  Serotype on the basis of Ag diversity More then Based on Each sub- Typing O-Ag it is group A satin of E.coli method: 700 divided included denoted as – Based on O, H Ag serotype into O- stain with O111: K58: H2 of E.coli Agglutination have been groups H-Ag assay, PCR, RFLP, identified and O- MLST,PFGE, group is MALDI-TOP, NGS whole divided genome analysis into sub- groups Not for diagnosis based on purposes only for research K-Ag and epidemiology studies  Factors of Pathogenicity and Virulence Surface Toxins (Exotoxins) – Two types of virulence Antigens two types factors: Surface Ags & Toxins LPS surface O Ag – Enterotoxins–pathogenesis endotoxic activity of diarrhea, 3 types: LT (heat-labile toxin), ST (heat stable toxin) & VT Envelope or K Ag – (verocytotoxin or shiga- protects against like toxin). phagocytosis Hemolysins Fimbriae – colonization, found in strains causing diarrhea and urinary tract infections  Heat labile toxin-LT Increased cAMP opens up LT–is heat labile and the chloride channel, binds to specific GM1 leading to Cl secretion into gangliosides receptors on the bowel lumen. Sodium epithelial cells of the small follows to maintain intestine where it electroneutrality. Resulting stimulates the production in secretory of cAMP. diarrhea/watery diarrhea -which is watery.  Heat Stable toxin-ST Activate guanylate cyclase Anti-absorption action Formation of cGMP in Ep resulting in cell causes Inhibition of co- diarrhoea(watery ). transport of Na-Cl into to wall.  Pathogenicity / Clinical Infections Pyogenic Diarrhoea: infections Infantile Septicaemia Wound diarrhoea, – can lead to Urinary tract infection- Traveller’s fatal Neonatal infection- especially diarrhoea, conditions meningitis. UTI after surgery Bloody/ like Septic of the lower Hemorrhagic shock intestinal diarrhoea tract.  Urinary tract infection-UTI Predisposing factors- Woman, >100000/mL pregnancy, of urine- sexual significant intercourse, bacteriuria Presences urinary and indicates