Salmonella, Shigella, and Yersinia Infections PDF

INFECTIONS DUE TO SALMONELLA, SHIGELLA and YERSINIA  Objectives Describe bacterial agents: SALMONELLA, SHIGELLA and YERSINIA that cause diarrhea Describe the clinical presentation of each infection List the recommended diagnostics and common findings for each...

INFECTIONS DUE TO SALMONELLA, SHIGELLA and YERSINIA  Objectives Describe bacterial agents: SALMONELLA, SHIGELLA and YERSINIA that cause diarrhea Describe the clinical presentation of each infection List the recommended diagnostics and common findings for each infection Understand the treatment and management  Salmonella and Salmonellosis a serious problem of public health in developing countries and in developed countries Salmonella the family Enterobacteriaceae Gram-negative rod-shaped facultative bacterium, Catalase + Oxidase – Lactose non-fermenter Salmonella: Morphology Gram-negative rod- Gram-negative rod- shaped shaped facultative bacterium, the family facultative bacterium, Enterobacteriaceae Catalase + Oxidase the family Enterobacteriaceae Catalase + Oxidase – H2S +  Salmonella SS agar Mac Conkey Hectoen-Enteric agar, Bismuth sulfide agar  Salmonella The genus Salmonella contains a large number of species. Classification of the genus Salmonella is complex, with 2500 serotypes Two species. S. enterica and S. bangori Sortened scientific name: Genus+serotype: (Salmonella enterica serotype Typhi) Clinically important Salmonella serotypes – Salmonella Paratyphi A (serogroup A) – Salmonella Paratyphi B (serogroup B) – Salmonella Typhi (serogroup D) Enteric fever – Salmonella Choleracuis (serogroup C1) Septicemia – Salmonella Typhimurium (serogroup B) Gastroenteritis  Salmonella The typhoidal The nontyphoidal species: species; the many serotypes of S. S. Typhi enterica S. Paratyphi (S. enterica serotype Choleraesuis )  Associated Infections 1 Enteric Fever (typhoid fever) (S. Typhi) Paratyphoid fever (mild form) (S. Paratyphi A,B,C) Asymphomatic colonization - develops after typhoid or paratyphoid fever - 1 – 5% of patients - Gallbladder reservoir for infection!  Typhoid Fever life-threatening infection affects 17 million people worldwide every year, ( 600,000 deaths) S. Paratyphi tends to cause a milder infection Typhoid Fever is common in children < 5 years old in developing countries  Transmission of Typhoid Fever food and water contaminated (by the feces and urine of patients and carriers) Carriers are source of infection (as food handlers)  Salmonella typhi: Enteric Fever T. F. has just returned from a family wedding in India. 27 y/o woman with 10 day h/o fever. Gradual onset of malaise and headache. Also had fever, faint macular rash on trunk Initially had constipation, then diarrhea. Immunizations: traveling companion, who isn't sick, received typhoid vaccine (patient didn't). Exam: 40ºC, HR 60, slightly enlarged liver & spleen. Labs: Blood and stool cultures: Gram negative rods Non-typhoidal Salmonellae Commensals of many animals, Most common sources Transmission is via the for humans: feacal-oral route – Poultry Infective dose is relatively high: ~106 – Eggs organisms – Dairy products Drug resistant salmonella (by: animal feeds containing antimicrobial drugs)  Associated Infections 2 Enteritis (by contaminated food or water) Septicemia Localized infections – Osteomyelitis – Endocarditis – Arthritis  Enteritis – the common Salmonellae infection – no human reservoir – Gastroenteritis nausea vomiting non-bloody stool self-limiting (2 - 5 days)  Laboratory Diagnosis Enterocolitis: Enteric fever: Culture of stool Isolation from blood samples 1.week Identification by From urine 2 &3. week biochemical From stool 1.week seroagglutination &2.week tests Serology (Widal test)- Phage typing unreliable results  Typhoid Fever Prevention ä To control of human reservoir ä To prevent contamination of water and food ä improvements of sanitary conditions ä vaccination (The currently licensed Vi polysaccharide vaccines are not very effective)  Typhoid -Therapy Antibiotics essential Chloramphenicol 10 days- Ampicillin 2 weeks TMP-SXT if there is resistance – Quinolone or 3rd gen. cephalosporins  Enterocolitis -Therapy Self-limiting Antibiotics (e.g. Ciprofloxacin) reserved for severe septicaemic cases particularly in the elderly, very young immunocompromised Centers for Disease Control and Prevention (CDC)  RESISTANCE OVER TIME CDC report 2019 Antibiotic-resistant nontyphoidal Salmonella Typhi nonsusceptible Salmonella to ciprofloxacin Shigella  Shigella Serogroup A: S. dysenteriae (12 serotypes) Serogroup B: S. flexneri, (14 serotypes) Serogroup C: S. boydii, (23 serotypes) Serogroup D: S. sonnei, (1 serotype) Distinguished by biochemical reaction and antigenic characteristics (“O” antigens) Shigellosis:Epidemiology Obligate human pathogen no animal "reservoir" mostly young children – fecal to oral contact with low infective dose ( Diarrhea, fever, abdominal pain Mesenteric Iymphadenitis (mimics acute appendicitis, most common in children ) Local necrosis granulation of Iymphnodes, spleen, liver... Hepatitis, intraabdominal abscess Septicemia Arthritis, Osteomyelitis  Y. pseudotuberculosis similar less severe disease Occasional cause of mesenteric adenitis Rarely septicaemia  Lab diagnosis Culture (27 C) Blood agar, non-haemolytic colonies Mac Conkey agar+ Animal models Serology >1/16 Thanks for your attention....  Host factors Age Personal hygiene Gastric acidity İntestinal motility Enteric microbiota immunity  Y. pestis A cause of plague (Black Death) Endemic in some areas of the world  Yersinia pestis Primarily a pathogen of rodents http://www.channel4.com/history/ microsites/H/history/plaegu/plague.h tml Science Picture Library  Transmitted to humans via infected fleas www.cdc.gov/ncidod/dvbid/ plague/cheob6x4.htm  Y.pestis Three form of human plague Bubonic-painful, swelling adenitis may spread, 50% fatal Pneumonic- result of droplets infec., highly contagious, fatal Septisemic  www.imcworldwide.org/ cbr/L1C-m2.html idcs0100.lib.iup.edu/ WestCivI/the8.htm  Lab diagnosis Demonsrating the bacilli in fluid, sputum or blood Methylene blue stain- Bipolar staining  Treatment When plague is suspected: antibiotics are started immediately – Tetracycline