خصوصیات کلی 40 جنس و 150 گونه ..کمتر از 20 جنس مسئول بیش از 90 در صد عفونتهاست. 35 درصد سپتی سمی ها بیش از 70 درصد عفونتهای ادرای بسیاری از عفونتهای روده ای پاتوژنهای این گروه (سالمونلا تایفی،شیگلا،یرسینیا پستیس) فرصت طلب ها (اشرشیا ،کلبسیلا و پروتئوس) انتقال فاکتورهای ویرولانس از طریق پلاسمید یا باکتریوفاژ

مخازن عفونتها :مخازن حیوانی (سالمونلا و یرسینیا) حاملان انسانی (شیگلا و سالمونلا تایفی) گسترش درونی (اشرشیاکلی) نکته:همه متحرک اند به جز شیگلا .کلبسیلا و یرسینیا کپسول :کلبسیلا انتروباکتر

Incidence of Enterobacteriaceae Associated with Bacteremia

Differentiation between LF & NLF by Growth on MacConkey agar Bile salts Crystal violet Lactose Neutral red Inhibit growth of G+ve bacteria pH indicator Acidic: Pink Cause of differential Cause of selectivity Lactose non feremnters colorless colonies Lactose feremnters Pink colonies

Enterobacteriaceae Lactose Non-Fermenters Lactose Fermenters No acid Acid Neutral red Colorless colonies Pink colonies Escherichia coli Klebsiella spp Enterobacter spp Citrobacter spp Salmonella spp Schigella spp Proteus spp Yersinina spp

50 Flagella ‘H’ antigen Fimbriae/Pili ‘F (K)’ antigen Capsule ‘K’ antigen 100 150 LPS ‘O’ antigen

Serologic identification based on presence or absence of several antigenic structures

Antigenic Structure of Enterobacteriaceae S. typhi O antigen side chain (Fimbriae)

Exotoxins also known as enterotoxins: Produced and secreted by the organism Also play a major role in the pathogenicity of many of these organisms Causes severe gastrointestinal symptoms such as nausea, vomiting, diarrhea, fluid loss, and cramping

Pedestal formation

E. coli toxins ST: is heat stable and binds to specific receptors to stimulate the production of cGMP with the same results as with LT

Shiga-type toxin: Also called the verotoxin Is cytotoxic, enterotoxic, neurotoxic May cause diarrhea and ulceration of the G.I. tract Two types shiga-like toxin 1 and shiga-like toxin 2. Inhibit protein synthesis by cleaving a 28S rRNA that’s part of the 60S subunit

Type III secretion system

اشرشیا اینترواگرسیو اسهال حاد یا مزمن (14روزه) در ایدزی ها مکانیسم بیماریزایی کاملا مشخص نیست سپسیس:به دنبال عفونت ادراری یا اسیب به روده در نوزادان شدیدتر (فقدان انتی بادی IgM) مننژیت:باکتری بصورت فلور در مجاری معده ای روده ای زنان باردار و نوزادان تازه متولد شده..75 درصد انتی ژن K1

Klebsiella. sp Opportunistic bacteria Includes: Klebsiella pneumoniae (K. friedlanderi) responsible for most infections found in the RT of 10% of the population Klebsiella oxytoca Klebsiella ozaenae Klebsiella rhinoscleromatis Gram (-) Lactose fermenter in MacConkey Mucoid capsule

Determinants of Pathogenicity Capsule (mucoid), antiphagocytic and major virulence factor type 1,2 respiratory infection and type 8,9,10 urinary infection Some strains produce toxins similar to heat-labile (LT) and heat-stable (ST) toxins of E. coli Antibiotic resistance to most antibiotics

Enterobacter sp. Species: Enterobacter aerogenes Enterobacter agglomerans Enterobacter cloacae Often found in the normal intestinal flora, soil and water Differentiated from other enterobacteriaceae based on biochemical characteristics Causes nosocomial infections esp. of urinary tract, bacteremia and septicemia Produces beta-lactamase  inactivates penicillins and 1st- gen. cephalosporins

Serratia sp. water & soil red pigment - prodigiosin Serratia marcescens – nosocomial surgical wound infections, UTI, RTI, septicemia Treatment: aminoglycosides, chloramphenicol, trimethoprim-sulfa- methoxazole

Proteus sp. Species: Proteus mirabilis Proteus vulgaris Gram (-) rod Extremely motile – numerous and long peritrichous flagella (“swarming phenomenon”) Produce urease Produce H2S from sodium thiosulfate Ferment indole (P. vulgaris) Produce phenylalanine deaminase

Morganella morganii Providencia sp. Closely related to Proteus indole fermenters Urease producers but most Providencia species are not Produce phenylalanine deaminase Nosocomial UTI, pneumonia, bacteremia

Citrobacter sp. Closely related to Salmonella Found in the environment Citrobacter freundii Citrobacter diversus Closely related to Salmonella Found in the environment Stool’s normal flora Opportunistic bacteria Causes: UTI, diarrhea (in children), wound infections, septicemia and neonatal meningitis brain abscesses (C. diversus) C. freundii - can be enterotoxigenic

Salmonella “species” No. of serotypes Species Subspecies Isolated from: S.enterica S.bongori I II IIIa IIIb IV VI >1300 464 64 309 10 93 17 warm-blooded animals Cold-blooded animals V

Major species Salmonella typhi (the only systemically invasive specie) - Typhoid fever, only in humans 2. Salmonella enteritidis, S. enteritidis typhimurium - enterocolitis (salmonellosis) - diarrhea, fever, abdominal pain - dehydration and electrolyte imbalance 3. Salmonella choleraesuis

Salmonella attachment: fimbriae Each serotype can produce many different types of fimbriae/pili Eg S.typhimurium has genes for 13 different types of pili

12 PIs identified in Salmonella, strain may not have all PIs. Salmonella chromosome Type III secretion system Invasion of epithelial cells Enteritis SPI 1 SPI 2 Type III secretion system Survival in macrophages 12 PIs identified in Salmonella, strain may not have all PIs.

Salmonellae may cause disease or colonise the gut of a host and cause no disease Salmonella are invasive, facultative intracellular pathogens Important syndromes are: 1. ENTERITIS resulting in diarrhoea, organisms restricted to gut tissue, don’t invade beyond mesenteric lymph node 2. SEPTICAEMIA organisms spread throughout body and grow in different organs, eg, liver and spleen, made lead to abortion or joint infections or pneumonia. May or may not be diarrhoea

Enteritis Septicaemia Macrophage Liver MLN Neutrophil Spleen M cell Enterocyte Tight junction M cell Macrophage Neutrophil Enteritis MLN Liver Spleen Septicaemia

Lysosome Phagosome H+ H+ Phagolysosome fusion Acidification Prevent fusion H+ Survival in phagososome Phagosome H+

Salmonella typhi Symptoms Pathogenesis Typhoid Fever contaminated food or water infections at other sites low infectious dose involve lymphatic and circulatory systems Symptoms severe fever/headache apathy, weakness, abdominal pain and rash. 1-3% recovered patients become carriers, harboring Salmonella in their gallbladder

Based on somatic O antigen Antigenic structure Complex, there are more than 40 sero types based on their LPS of somatic O antigen Based on somatic O antigen S. dysenteriae (A) S. flexneri (B) S. boydii (C) S. sonnei (D)

Shigellosis Shigella spp. producing Shiga toxin Shiga toxin causes inflammation and bleeding

Incubation period 1-2 days. Sudden onset of Clinical features Incubation period 1-2 days. Sudden onset of Abdominal pain, fever and Watery diarrhoea, Mucus and bloody stools. Fever and diarrhea subsides 2-5 days. Loss of water (dehydration). Chronic carrier status may result.

Sources of in infection Contaminated water Contaminated dairy products Shellfish Dried or frozen eggs Meat and meat products of infected animals Household pets

Dysentery carriers There are healthy carriers in the community This will happen after an attack Will excrete in the bacilli intermittently for few weeks - small proportion can become persistent carriers

Microorganism Mechanisms Diseases Transmission Treatment Prevention CLINICAL SUMMARY TABLE Virulence Microorganism Mechanisms Diseases Transmission Treatment Prevention Salmonella typhi Not killed by Typhoid Fecal oral, Broad Water and macrophages, Fever carriers spectrum sewage tx, Endotoxins antibiotics Vaccines, Control carriers Salmonella sp. Endotoxins Gastroenteritis Food & Supportive Proper waterborne Rx cooking, Sanitary procedures Shigella sp. Shiga toxin Dysentery Fecal-oral Rehydration Good Endotoxins Antibiotics hygiene Escherichia coli Enterotoxins Traveler’s Fecal-oral Rehydration Proper Shiga-like toxin diarrhea, Opportunists Antibiotics? food Attachment pili/ Hemorrhagic don’t help- handling, fimbriae colitis, harmful Good Urinary tract infections/Nosocomial infections sanitation

Diagnostic tests Specimens-Urine, blood, pus, CSF, Sputum, Stools Smear Culture blood agar Immunity is not satisfactory. Management No single specific therapy available Sulfonamides Ampicillin Cephalosporines Fluoroquinolone Aminoglycoside

Non-lactose fermenters Pathogens of warm blooded animals SALMONELLA Indole -ve Non-lactose fermenters Pathogens of warm blooded animals “commensals” of cold blooded animals

Selective media/indicators Pale (yellowish) colonies on MacConkey agar Alkaline reaction (red colonies) on brilliant green agar On XLD (xylose-lysine deoxicholate), red colonies with black centre (H2S) API 20E kit if available (very useful). Typically, on TSI, most Salmonella spp. give red (alkaline) slant, yellow (acidic) butt, and black (H2S) production. (R/Y/H2S+)

Salmonella isolation and identification API 20E: commercial kit of many biochemical tests in single raw

HEKTOEN ENTERIC(HE) AGAR Hektoen enteric agar is a medium designed for the isolation and recovery of fecal specimens belonging to the Enterobacteriaceae family, especially Salmonella and Shigella. It can differentiate between bacteria that ferment lactose and those that don't. Acid produced from fermenting lactose imparts a yellow-orange color to the medium due to the presence of a pH indicator. Non-lactose fermenters do not significantly change the color of the medium. HE agar can also detect the production of hydrogen sulfide gas, which turns parts of the medium black.

INTERPRETATION OF TUBES ABOVE TUBE 1 (UNINOCULATED) TUBE 2 TUBE 3 TUBE 4 TUBE 5 SLANT - A K BUTT HYDROGEN SULFIDE + GAS A=Acidic K=Alkaline

The End