MOD 14 Bacterial Infections of the CVS and Lymphatics 2 PDF

MICROBIOLOGY AND PARASITOLOGY 11/06/2024. MOD 14: BACTERIAL INFECTIONS OF THE CVS AND LYMPHATICS 2...

MICROBIOLOGY AND PARASITOLOGY 11/06/2024. MOD 14: BACTERIAL INFECTIONS OF THE CVS AND LYMPHATICS 2 Dr. Carlo Gabriel R. Macapagal Trans Group/s: 3A OUTLINE PART 1 I. Enterobacteriaceae I. ENTEROBACTERIACEAE A. Characteristics A. CHARACTERISTICS OF ENTEROBACTERIACEAE B. Antigenic Structures A large, heterogenous group of gram (-) rods 1. O Antigens Natural habitat 2. K Antigens / Capsular Antigens ○ Intestinal tract of humans and animals 3. H Antigens / Flagellar Antigens Shared characteristics II. Escherichia coli ○ Facultative anaerobes, ferment glucose, reduce nitrate and are oxidase-negative A. Clinical Diseases Presumptive Identification of Gram (-) Enteric Bacteria 1. Urinary Tract Infection ○ Lactose fermented rapidly: Escherichia coli, 2. E. coli-Associated Diarrheal Diseases Enterobacter, Klebsiella 3. Meningitis ○ Lactose fermented slowly: Serratia, some strains 4. Sepsis of Shigella sonnei (on extended incubation), B. Laboratory Tests Salmonella Arizona subgroup 1. Microscopic Morphology and Culture ○ Lactose not fermented: Proteus species, Salmonella species, Shigella species 2. Triple Sugar Iron Test (TSI) 3. IMViC Test C. Treatment D. Prevention III. Salmonella sp. A. Characteristics B. Classifications C. Clinical Diseases 1. Enteric Fever (Typhoid Fever) 2. Enterocolitis D. Laboratory Diagnosis E. Bacteriologic Methods 1. Differential Medium Cultures 2. Selective Medium Cultures 3. Enrichment Cultures Rapid, Presumptive Identification of Gram-Negative Enteric 4. Serologic Methods Bacteria F. Immunity G. Treatment B. ANTIGENIC STRUCTURES OF ENTEROBACTERIACEAE H. Prevention 1. O ANTIGENS IV. Proteus sp. > 150 Heat-stable somatic O Antigen A. Characteristics Most external part of the cell wall B, Laboratory Diagnosis Resistant to heat and alcohol C. Treatment Antibodies are predominantly IgM D. Prevention V. Serratia sp. 2. K ANTIGENS / CAPSULAR ANTIGENS A. Characteristics > 100 B. Laboratory Diagnosis Heat-labile C. Treatment Capsular antigens interfere with agglutination by O antisera cause attachment of E. coli to epithelial cells D. Prevention before invasion OBJECTIVES 3. H ANTIGENS / FLAGELLAR ANTIGENS 1. Identify the etiologic agent based on the general > 50 characteristics and laboratory findings. Located on the flagella 2. Determine the associated clinical diseases, risk Denatured by heat/alcohol factors, and transmission of a specific etiologic agent. Agglutinate mainly with IgG 3. Identify the appropriate management and control May interfere with agglutination by anti-O antibody measures for a given infectious agent. Microbiology - Mod 14 Bacterial Infections of the CVS and Lymphatics 2 1 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  B. LABORATORY TESTS OF E. COLI 1. MICROSCOPIC MORPHOLOGY AND CULTURE Gram-negative bacilli Gram 1 Facultative anaerobes Staining Lactose fermenters Colonies formed: green metallic sheen EMB contains lactose and 2 EMB Agar sucrose If fermented: bacteria produces a dark-purple complex with a green metallic sheen MacConkey 3 Colonies formed: pink colonies Agar Antigenic Structures of Enterobacteriaceae II. ESCHERICHIA COLI Normal microbiota of the bowel of humans and other animals May also inhabit female genital tract For non-gastrointestinal infection ○ Endogenous or person-to-person For gastrointestinal infections ○ Transmission mode varies with the strain of E. coli Laboratory Testing of E. Coli ○ May involve: Fecal-oral spread between humans in 2. TRIPLE SUGAR IRON TEST (TSI) contaminated food, water, or consumption of TSI is an agar with multiple sugars undercooked beef or unpasteurized milk This allows differentiation among organisms based on the differences in carbohydrate fermentation and A. CLINICAL DISEASES OF E. COLI hydrogen sulfide production 1. URINARY TRACT INFECTION CONSISTS OF E. coli is the most common cause of UTI Uropathogenic E. coli: colonizes the bladder or the 1 Phenol red dye kidney and causes infection due to O antigen ○ Produces hemolysin which facilitates invasion 2 1% lactose ○ Can result in bacteremia with signs of sepsis 3 1% sucrose 2. E. COLI-ASSOCIATED DIARRHEAL DISEASES 4 0.1% glucose Sodium thiosulfate, ferrous sulfate, or ferrous Enteropathogenic Diarrhea in infants 5 1 ammonium sulfate E. coli (EPEC) Enterotoxigenic Traveler’s diarrhea 2 TSI TEST INTERPRETATION E. coli (ETEC) Shiga toxin-producing Hemorrhagic colitis 1 Produces orange-red to yellow 3 Acidic (A) E. coli (STEC) Organism is acidic Enteroinvasive Dysentery 4 2 Produces orange-red to deep red E. coli (EIEC) Alkaline (K) Acute & chronic Organism is alkaline Enteroaggregative 5 diarrhea; persistent E. coli (EAEC) 3 Bubbles Positive (+) = gas production diarrhea in HIV patients For E. coli (image above): Since it is yellow on both the 3. MENINGITIS slanted and lower part, it is A/A. Leading cause in infants 80% of E. coli have the K1 antigen 1st tube (left) A/A, with gas production 2nd tube (right) A/A, without gas production 4. SEPSIS E. coli may reach the bloodstream and cause sepsis when normal host defenses are inadequate Newborns may be highly susceptible because they lack IgM antibodies Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 2 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  SUMMARY OF BIOCHEMICAL TESTS FOR E.COLI TRIPLE A or K/A reaction with or without SUGAR IRON gas, (-) H2S INDOLE Positive METHYL RED Positive VOGUES- PROSKAUER Negative CITRATE Negative OXIDASE Negative E. coli on Triple Sugar Iron Test (TSI) NITRATE Positive 3. IMViC Test H2S Negative Biochemical test for the identification of UREASE Negative Enterobacteriaceae ACID PRODUCED FROM LACTOSE Positive IMViC Tests of E. coli Generated by reductive Results for Triple Sugar Iron (TSI) test can be: deamination from tryptophan ○ A/K or A/A reaction with or without gas Positive: Bright pink color on top ○ (-) Hydrogen Sulfide (H2S) production Indole 1 layer E.coli is POSITIVE for Indole, Methyl Red, Nitrate, and Test Determines if an organism has the acid produced from lactose. capacity to degrade tryptophan E. coli: Positive (+) C. TREATMENT OF E. COLI Determines if glucose can be Fluoroquinolones, such as Ciprofloxacin and Methyl converted to acidic products such Levofloxacin are the first-line therapy. 2 Azithromycin is commonly used for invasive E.coli Red Test lactate, acetate, and formate E. coli: Positive (+) infections. Antibiotic susceptibility testing may be essential due to Voges- Determines if glucose can be emerging multidrug resistance. 3 Proskauer converted to acetone Test E. coli: Negative (-) D. PREVENTION OF E. COLI Frequent handwashing, aseptic technique, sterilization Determines if an organism has the of equipment, and disinfection. ability to utilize citrate as a source of energy PART 2 When the bacteria metabolize Citrate citrate, ammonium salts are 4 Utilization broken down to ammonia which III. SALMONELLA SP. Test increases alkalinity. Shift in pH = changes A. CHARACTERISTICS OF SALMONELLA bromothymol indicator from Gram-negative bacilli green to blue Shared Characteristics E. coli: Negative (-) ○ Non-spore forming; Facultative anaerobes; Oxidase-negative Utilizes ○ Citrate as carbon source ○ Lysine as nitrogen source Produces ○ H2S, form acid and sometimes gas from the fermentation of glucose and mannose Resistant to ○ Brilliant green, sodium tetrathionate, and sodium deoxycholate that inhibit other enteric bacteria; ○ Useful to specifically isolate Salmonella species from feces Acquired through oral route and transmitted via contaminated food or water Causes enteritis, systemic infection, and enteric fever The main infectious dose to produce clinical or E. coli on IMViC Test 5 8 subclinical infections in humans is 10 to 10. The infectious dose for typhoid fever caused by salmonella typhi is significantly lower, less than or equal 3 to 10 organisms Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 3 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  SOURCES OF INFECTION 1. ENTERIC FEVER (TYPHOID FEVER) A severe, systemic illness, caused by Salmonella typhi 1 Water Fecal contamination (most common) or Salmonella paratyphi. Ingestion Milk and other ○ After ingestion of contaminated food or beverage, Fecal contamination, inadequate 2 dairy the salmonella reaches the small intestine (M-cells pasteurization, or improper handling products overlying the Peyer’s patches) from which they pass through the epithelium and enter the intestinal 3 Shellfish Contaminated water lymphatics with subsequent invasion into the Dried or Infected fowl or contaminated during bloodstream. 4 ○ Via the bloodstream, the salmonella is spread to frozen eggs processing many other organs Infected animals (poultry) or ○ The organism also multiplies within the intestinal Meats and lymphoid tissue and is excreted in stools after an 5 contamination with feces by rodents meat products incubation period of 10-14 days. or humans Incubation period 6 Marijuana and other recreational drugs ○ 10-14 days ○ accompanied by the following symptoms: 7 Animal dyes Fever (39.0°C to 40°C) Malaise 8 Household pets Headache Constipation B. CLASSIFICATIONS OF SALMONELLA Bradycardia Salmonella is divided into two species, each with Myalgia multiple subspecies and serotypes: Spleen & Liver enlargement ○ Salmonella enterica Rose spots Majority of the clinical diseases are caused by ○ Classic cutaneous manifestation of enteric fever S. enterica subspecies 1 strains that is typically observed on the chest and Classified as “typhoidal” and “non-typhoidal” abdomen. Typhoidal Salmonella refers to ○ 1-4 mm blanching pink macules. serotypes that cause typhoid (“enteric”) ○ Fairly uncommon. fever (serotypes Typhi, Paratyphi A, Abdominal symptoms: diarrhea, constipation, & general Paratyphi B, and Paratyphi C) abdominal pain. Non-typhoidal Salmonella refers to all WBC count is usually normal or low. other serotypes. ○ Salmonella bongori 2. ENTEROCOLITIS Classified by their serotype which is according to surface structures: somatic O antigens and flagellar H The most common manifestation of Salmonella antigens infection. After ingestion of contaminated food and water (usually C. CLINICAL DISEASES OF SALMONELLA 8-48 hours), patients will develop: ○ Nausea Enteric fever Septicemias Enterocolitis ○ Headache Incubation ○ Vomiting Period 7 - 20 days Variable 8 - 48 hours ○ Profuse diarrhea Low-grade fever (38°C to 39°C) & abdominal cramping Onset Insidious Abrupt Abrupt are very common clinical symptoms. Diarrhea is usually self-limited (3 to 7 days). Gradual; then Rapid rise; Bacteremia is a rare (2-4%) complication, except in high plateau then spiking immunocompromised patients Fever Usually low with “typhoidal “septic” Blood culture results are usually negative. state” temperature Stool cultures are positive & may remain for several weeks after recovery. Duration of Several The mean duration for carriage is 4-5 weeks. Disease Variable 2 - 5 days weeks Often early D. LABORATORY DIAGNOSIS OF SALMONELLA Nausea, Gastro- constipation; vomiting, intestinal later, Often none SPECIMENS Symptoms diarrhea at bloody onset diarrhea Freshly passed stool Specimens collected during the early Positive in enteric illness have the highest yield Blood first to Positive Non- 1 for the recovery of the infectious Culture second weeks during Negative typhoidal agent. Results of high fever Multiple stool specimens may enhance disease the recovery rate of Salmonella Positive from Culture (Salmonella Typhi or Paratyphi) second week specimens from blood, bone marrow, Stool 2 Typhoidal on; Infrequently Positive soon urine, intestinal secretions & other sterile Culture Results negative positive after onset sites earlier in disease Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 4 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  Blood 4. SEROLOGIC METHODS 3 Positive in the 1st week of illness Serologic techniques are used to identify unknown culture cultures with known sera Urine May also be used to determine antibody titers 4 Positive after the 2nd week of illness culture 1 AGGLUTINATION TEST Bone Highest sensitivity (80-95%) but less 5 marrow practical Known sera + unknown culture Positive Result: Clumping is observed within a few E. BACTERIOLOGIC METHODS OF SALMONELLA minutes Particularly useful for rapid preliminary identification 1. DIFFERENTIAL MEDIUM CULTURES EMB, MacConkey, or Permits rapid detection of lactose 1 deoxycholate non-fermenters medium Bismuth sulfite Black colonies because of H2S 2 medium production Salmonellae ferment glucose, WIDAL TEST (TUBE DILATATION 3 TSI agar slant but not lactose (K/A) 2 AGGLUTINATION TEST) They produce H2S and gas Serial dilutions of unknown sera are tested against antigens from representative Salmonellae. Detects antibodies against O & H antigens Positive Result: Titers of O antigen > 1:320 and H antigen > 1:640 or the agglutination in the 1:160 or 1:320 dilution Serum agglutinins rise sharply during the 2nd and TSI agar slant of Salmonella 3rd weeks of serotype Typhi infection. ○ At least two serum specimens obtained an 2. SELECTIVE MEDIUM CULTURES interval of 7-10 days are needed to prove a rise Specific recovery of Salmonella in antibody titer. ○ Chromogenic Agar Results cannot be relied upon to establish a definitive These favor growth of salmonellae and shigellae over diagnosis of typhoid fever and are most often used in other Enterobacteriaceae resource-poor areas of the world where blood cultures ○ Salmonella-shigella (SS) agar are not readily available. ○ Xylose-Lysine Deoxycholate (XLD) agar ○ Desoxycholate-Citrate agar ○ Hektoen enteric (HE) agar Hektoen enteric (HE) agar of Salmonella Salmonella species do not ferment the carbohydrates present in the HE agar; however, the organism produces H2S and ferric ammonium citrate in HE agar F. IMMUNITY OF SALMONELLA resulting in the Salmonella colonies appearing black. There is a certain degree of immunity in Salmonella typhi or Salmonella parathypi infections. 3. ENRICHMENT CULTURES Circulating antibodies to O and Vi are related to Inhibit normal intestinal bacteria and Permit resistance to infection. multiplication of salmonellae Secretory IgA antibodies may prevent attachment of ○ Selenite F or Tetrathionate broth salmonellae to intestinal epithelium. Sickle cell disease/trait patients: children are more susceptible to Salmonella infections especially bacteremia and its complications (eg, osteomyelitis) when compared to people with normal hemoglobin. Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 5 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. G. TREATMENT OF SALMONELLA 6 Deaminate phenylalanine Azithromycin 1g once, followed by 500 mg daily for 7 days 7 Grow on potassium cyanide medium Patient with complications: hospitalization & treatment with parenteral 3rd generation cephalosporin or 8 Ferment xylose fluoroquinolone for at least 10 days. Non-typhoidal Salmonella bacteremia: 3rd generation cephalosporin (eg, ceftriaxone) + Fluoroquinolone Endovascular infection (eg. infected aneurysm): IV ceftriaxone, ampicillin, or fluoroquinolone for 6 weeks, followed by oral therapy. ○ Early surgical resection of the infected aneurysm is also recommended. Salmonella gastroenteritis: usually self-limited but TSI Reaction. K/A reaction, with or without gas; H2S (+) replacement of fluids & electrolytes is needed in cases with severe diarrhea Antimicrobial treatment should be considered in neonates, immunocompromised, and elderly patients. ○ Amoxicillin, trimethoprim-sulfamethoxazole, or fluoroquinolone Chronic carriers (gallbladder): ampicillin alone or combined with cholecystectomy. H. PREVENTION OF SALMONELLA Thoroughly cook poultry, meat, and eggs. Carriers must not be allowed to prepare or handle food & should observe strict personal hygiene. VACCINES ○ Oral live, attenuated vaccine Indole Test. P. vulgaris (+), P. mirabilis (-) ○ Parenteral Vi capsular polysaccharide vaccine for intramuscular use Recommended for travelers to endemic regions Efficacy: 50-80% IV. PROTEUS SP. A. CHARACTERISTICS OF PROTEUS Gram-negative bacilli Normal inhabitants of the intestinal tract Shared Characteristics: ○ Non-spore-forming; Facultative anaerobes; Highly motile Most commonly cause infections ○ P. mirabilis: UTI, bloodstream & respiratory tract infections Swarming motility ○ P. vulgaris: wound and soft tissue infections Virulence factors: ○ Fimbriae: adherence ○ Flagella: motility ○ LPS: biofilm formation ○ Urease production B, LABORATORY DIAGNOSIS OF PROTEUS Specimen: urine, blood, or wound Peritrichous flagella C. TREATMENT OF PROTEUS RESULTS P. mirabilis is resistant to nitrofurantoin but most often susceptible to penicillins (e.g. ampicillin and amoxicillin), Move very actively utilizing peritrichous trimethoprim-sulfamethoxazole, cephalosporins, Swarming 1 flagella on solid media resulting in a aminoglycosides & imipenem motility characteristic wave-like appearance P. vulgaris is more resistant to various antibiotics (ampicillin, amoxicillin, & piperacillin) Rapid hydrolysis of urea with release of ○ The most active antibiotics for P. vulgaris and other 2 Urease (+) ammonia urine becomes alkaline stone members of the group are aminoglycosides and formation broad-spectrum cephalosporins P. vulgaris (+) D. PREVENTION OF PROTEUS 3 Indole test Frequent handwashing, aseptic technique, sterilization P. mirabilis (-) of equipment, and minimize duration of urinary TSI K/A reaction, with or without gas; H2S catheterization 5 reaction (+) Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 6 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  V. SERRATIA SP. C. TREATMENT OF SERRATIA Treatment is usually difficult due to resistance to multiple A. CHARACTERISTICS OF SERRATIA antibiotics Motile and slow lactose fermenters No empiric guidelines are available for the treatment of Common opportunistic pathogens and colonizers in infections due to S. marcescens because antibiotic hospitalized patients susceptibility varies by strain Transmitted from person to person, but transmission via S. marcescens: resistant to penicillin, ampicillin, and medical devices, intravenous fluids, and indwelling first-generation cephalosporins due to chromosomal catheter may also occur AmpC beta-lactamase Serratia marcescens – most frequently isolated Resistance to fluoroquinolones and ○ Causes pneumonia, bacteremia, wound infections, trimethoprim-sulfamethoxazole has also been described meningitis, bone and soft tissue infections, and endocarditis (IV drug users) D. PREVENTION OF SERRATIA The urinary tract is the most common site of infection Frequent handwashing, aseptic technique, sterilization Virulence factors: Lipopolysaccharide and biofilm of equipment, and proper use of antibiotics formation REFERENCES B. LABORATORY DIAGNOSIS OF SERRATIA Macapagal, C. (2024). Bacteria Associated with CVS & Specimen: urine, blood, sputum, or wound Lymphatics 2. Lecture Video Prodigiosin Pao, C. (2022). Bacteria Associated with CVS & ○ Red pigment produced by some Serratia species Lymphatics 2. Lecture Video ○ Only about 10% of the clinical isolates of S. Riedel, S., et al. (2019) Jawetz, Melnick & Adelberg’s marcescens produce this pigment Medical Microbiology. 28th ed., McGraw-Hill. Tille, P. (2017). Bailey & Scott’s Diagnostic Microbiology. 14th ed., Elsevier. Serratia sp. with prodigiosin red pigment Positive (+) for: ○ DNAse ○ Nitrate ○ Citrate ○ Ornithine decarboxylase ○ Voges-Proskauer TSI: A/A or K/A with or without gas TSI result showing K/A or A/A with gas production Microbiology - Mod 14 🏠 Bacterial Infections of the CVS and Lymphatics 2 7 of 7 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.