Batterjee Medical College

Dr. Manal El Said Ass. Prof. of Medical Microbiology Non Lactose-Gram Negative Bacilli

Batterjee Medical College Typhoid fever. Salmonella typhi Diseases Characteristics Habitat is the human colon only. Transmission is by fecal–oral route. Habitat and Transmission Facultative gram-negative rods. Non–lactose-fermenting. Produces H2S.

Batterjee Medical College Infects the cells of the reticuloendothelial system, especially in the liver & spleen. Endotoxin in cell wall causes fever. Capsule (Vi antigen) is a virulence factor. Predisposing factors: Decreased stomach acid resulting from ingestion of antacids or gastrectomy. Chronic carrier state established in gallbladder. Organism excreted in bile fecal–oral spread to others. Pathogenesis Salmonella typhi

Batterjee Medical College Pathogenesis Salmonella typhi

Batterjee Medical College Gram-stained smear and culture. Non–lactose-fermenting colonies on MacConkey's agar. Laboratory Diagnosis Salmonella typhi The used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar & xylose-lisine-deoxycholate (XLD) agar. They contain both selective and differential ingredients

Batterjee Medical College TSI agar shows alkaline slant and acid butt, with no gas and a small amount of H2S. Laboratory Diagnosis Salmonella typhi

Batterjee Medical College Biochemical and serologic reactions used to identify species. Identity by using known antisera against O, H, & Vi antigens. Widal test detects agglutinating antibodies to O & H antigens in patient's serum, but its use is limited. Laboratory Diagnosis Salmonella typhi

Batterjee Medical College Most effective drug is ceftriaxone. Ampicillin & trimethoprim-sulfamethoxazole can be used in patients who are not severely ill. Resistance to chloramphenicol & ampicillin is mediated by plasmid-encoded acetylating enzymes and β-lactamase, respectively. Salmonella typhi Treatment

Batterjee Medical College Public health measures: - Sewage disposal - Chlorination of the water supply - Stool cultures for food handlers - Handwashing prior to food handling. Two vaccines are in common use: - one vaccine contains purified Vi polysaccharide capsule - other vaccine contains live attenuated S. typhi Salmonella typhi Prevention

Batterjee Medical College Salmonella enteritidis (Salmonella enterica) Diseases Characteristics Enterocolitis. Sepsis with metastatic abscesses. Facultative gram-negative rods. Non–lactose-fermenting. Produces H2S. Motile.

Batterjee Medical College Pathogenesis Habitat is the enteric tract of humans & animals, e.g., chickens & domestic livestock. Transmission is by the fecal–oral route. Habitat and Transmission Invades the mucosa of small & large intestines. Enter blood sepsis. Infectious dose is at least 10 5 organisms because organism is inactivated by stomach acid. Endotoxin in cell wall. Predisposing factors: lowered stomach acidity from antacids or gastrectomy. Salmonella enteritidis (Salmonella enterica)

Batterjee Medical College Laboratory Diagnosis Gram-stained smear and culture. Non–lactose-fermenting colonies on MacConkey's agar. Salmonella enteritidis (Salmonella enterica) Lactose positive colonies of Klebsiella pneumoniae (larger) and lactose negative colonies of Salmonella enterica ssp.enterica on McConkey agar. Salmonella enterica ssp. enterica on Salmonella Shigella (SS) Agar. Lactose negative, H2S positive colonies.

Batterjee Medical College Laboratory Diagnosis TSI agar shows alkaline slant & acid butt, with gas & H2S. Salmonella enteritidis (Salmonella enterica)

Batterjee Medical College Laboratory Diagnosis Biochemical & serologic reactions used to identify species. Antisera is used to identify by using known in agglutination assay. Widal test detects antibodies in patient's serum to the O and H antigens of the organism but is not widely used. Salmonella enteritidis (Salmonella enterica)

Batterjee Medical College Treatment Antibiotics not recommended for uncomplicated enterocolitis. Ceftriaxone are used for sepsis depending on sensitivity tests. Resistance to ampicillin and chloramphenicol is mediated by plasmid-encoded β-lactamases & acetylating enzymes, respectively. Salmonella enteritidis (Salmonella enterica)

Batterjee Medical College Prevention Public health measures Do not eat raw eggs or meat. No vaccine is available. Salmonella enteritidis (Salmonella enterica)

Batterjee Medical College Shigella Species (e.g., S. dysenteriae, S. sonnei) Diseases Characteristics Enterocolitis (dysentery). Facultative gram-negative rods. Non–lactose-fermenting. Nonmotile

Batterjee Medical College Pathogenesis Habitat and Transmission Habitat is the human colon only No animal carriers Transmission is by the fecal–oral route. Invades the mucosa of the ileum and colon sepsis (rare) Endotoxin in cell wall. The infectious dose of Shigella is low (1–10 organisms) because it is resistant to stomach acid. Children in mental institutions & day care centers experience outbreaks. No chronic carrier. Shigella Species (e.g., S. dysenteriae, S. sonnei)

Batterjee Medical College Laboratory Diagnosis Gram-stained smear and culture. Non–lactose-fermenting colonies on MacConkey's agar. Shigella Species (e.g., S. dysenteriae, S. sonnei) colonial morphology displayed by Shigella cultivated on a Hektoen enteric agar. Fecal flora with Shigella on MacConkey Agar Plates

Batterjee Medical College Laboratory Diagnosis TSI agar shows an alkaline slant with an acid butt and no gas or H2S. Identified by: - biochemical reactions - serology with anti-O antibody. Shigella Species (e.g., S. dysenteriae, S. sonnei)

Batterjee Medical College Treatment Fluid & electrolyte replacement. In severe cases, ciprofloxacin. Resistance is mediated by : -Plasmid-encoded enzymes: ß-lactamase degrades ampicillin -Mutant pteroate synthetase sensitivity to sulfonamides. Shigella Species (e.g., S. dysenteriae, S. sonnei) Prevention Public health measures. No Prophylactic drugs. No vaccine.

Batterjee Medical College Dr. Manal El Said Proteus Species Head of Medical Microbiology Department

Batterjee Medical College UTI Sepsis Proteus Species (e.g., P. vulgaris, P. mirabilis) Diseases Characteristics Facultative gram-negative rods. Non–lactose-fermenting. Highly motile. Produce urease.

Batterjee Medical College Proteus Species (e.g., P. vulgaris, P. mirabilis) Habitat and Transmission Habitat is the human colon & environment (soil & water). Transmission to urinary tract is by ascending spread of fecal flora.

Batterjee Medical College Pathogenesis Endotoxin causes fever and shock associated with sepsis. Urease degrades urea to produce ammonia Ph. This leads to stones - Obstruct urine flow - Damage urinary epithelium - Serve as a nidus for recurrent infection (trapping bacteria within the stone. Organism is highly motile facilitate entry into bladder. Predisposing factors are: -Colonization of the vagina -Urinary catheters -Abnormalities of urinary tract (strictures, valves & stones) Proteus Species (e.g., P. vulgaris, P. mirabilis)

Batterjee Medical College Laboratory Diagnosis Gram-stained smear and culture. Swarming (spreading) effect over blood agar plate as the organism's active motility. Non–lactose-fermenting colonies on MacConkey's agar. Produces urease P. mirabilis is indole-negative Proteus Species (e.g., P. vulgaris, P. mirabilis)

Batterjee Medical College TSI agar shows an alkaline slant and acid butt with H 2 S. Laboratory Diagnosis Proteus Species (e.g., P. vulgaris, P. mirabilis)

Batterjee Medical College Treatment Trimethoprim-sulfamethoxazole or ampicillin is often used for uncomplicated UTIs A third-generation cephalosporin should be used for serious infections. The indole-negative species P. mirabilis is more likely to be sensitive to antibiotics such as ampicillin. Resistance is mediated by plasmid-encoded enzymes. Proteus Species (e.g., P. vulgaris, P. mirabilis)

Batterjee Medical College Prevention No vaccine or drug is available. Prompt removal of urinary catheters helps prevent urinary tract infections. Proteus Species (e.g., P. vulgaris, P. mirabilis)

Batterjee Medical College Morganella morganii & Providencia rettgeri Enteric gram-negative rod similar to Proteus species. Causes UTIs & sepsis. Highly motile & produces urease. Indole-positive and more resistant to antibiotics than P. mirabilis.

Batterjee Medical College Bubonic & pneumonic plague. Yersinia pestis Diseases Characteristics Reservoir is wild rodents, e.g. rats. Transmission is by flea bite. Small gram-negative rods with bipolar ("safety pin") staining. One of the most virulent organisms (very low ID 50) Habitat and Transmission

Batterjee Medical College Yersinia pestis Virulence factors include: Endotoxin Exotoxin, V & W proteins allow organism to grow within cells. Envelope (capsular) antigen that protects against phagocytosis. Pathogenesis Bubo is a swollen inflamed lymph node, located in the region of the flea bite

Batterjee Medical College Yersinia pestis Gram-stained smear. Wayson's stain show typical "safety-pin" appearance. Cultures are hazardous & done only in specially equipped laboratories. Organism is identified by immunofluorescence. Serologic tests that detect antibody in patient's serum. Laboratory Diagnosis

Batterjee Medical College Control rodent & avoid contact with dead rodents. Killed vaccine is available for high-risk occupations Close contacts should be given tetracycline. Streptomycin either alone or in combination with tetracycline. Strict quarantine for 72 hours Yersinia pestis Treatment Prevention

Batterjee Medical College Gram-negative rods. It Causes: -Enterocolitis (similar to Shigella & Salmonella). - Mesenteric adenitis (mimic appendicitis) Found in domestic animals Transmitted by fecal contamination of food. Yersinia enterocolitica