DOCSLIB.ORG

Section Six BACTERIA BACTERIAL RESPIRATORY INFECTIONS

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Section Six BACTERIA BACTERIAL RESPIRATORY INFECTIONS Section Six BACTERIA BACTERIAL RESPIRATORY INFECTIONS The upper respiratory tract may become susceptible to bacterial infection as a result of health conditions such as allergies and viral infections, as well as the effects of smoking and airborne environmental pollutants. BACTERIAL RESPIRATORY INFECTIONS Streptococcus pneumoniae, Haemophilus influenzae and Klebsiella pneumoniae are the most common bacterial pathogens in upper and lower respiratory tract infections. BACTERIAL RESPIRATORY INFECTIONS Bacterial pathogens adhere to mucous membranes and colonization ensues. In an otherwise healthy individual the host immune system responds to the invading bacteria resulting in edema and swelling. BACTERIAL RESPIRATORY INFECTIONS If antimicrobial treatment does not eradicate the invading organisms and successfully interrupt the progress of the infection, the patient may develop recurrent or chronic disease. BACTERIAL RESPIRATORY INFECTIONS S. pneumoniae and other pathogens once susceptible to Penicillin and other antibiotics are now becoming resistant. Bacterial resistance has developed and disseminated because of the widespread use of antibiotics. BACTERIAL RESPIRATORY INFECTIONS Major mechanisms of bacterial resistance to antimicrobials in upper respiratory tract infections include membrane impermeability, alteration of the target inside bacterial cells and active pumping out of antibiotic (efflux). 1) Test for Bacterial respiratory infections Using Blood Agar Procedure 1- Suspend 28 grams of nutrient agar in 1000 ml purified/distilled water. 2- Heat to boiling to dissolve the medium completely. 3- Sterilize by autoclaving at 1.5 atm (121°C) for 15 minutes. 4- Cool to 45-50°C. 5- Add 5% sterile defibrinated blood (warmed to room temperature) and mix gently but well (avoid Air bubbles). 5- Plating using pour plate method (add 0.1 ml of sample and then pour the medium and mix gently. 6- Invert the agar plates and put them in the incubator at 37°C for 24-48 hrs. 7- After incubation period, examine the plates and write your observation. Observation 1- Alpha hemolysis: Partial lysis of the RBC to produce a greenish-grey or brownish discoloration around the colony. α hemolysis is due to the reduction of RBC hemoglobin to methemoglobin in the medium surrounding the colony. Example: Streptococcus pneumoniae. Observation clearing of blood 2- Beta Hemolysis: Complete lysis of red blood cells causing a clearing of blood from the medium under and surrounding the colonies. Example: Streptococcus pyogenes. Observation 3- Gamma or non-hemolysis: No hemolysis of RBC. No change of the medium under and surrounding the colonies. Example: Klebsiella pneumoniae. Comment Blood agar is an enriched, bacterial growth medium. Fastidious organisms, such as Streptococci spp., do not grow well on ordinary growth media. Blood agar is a type of growth medium (Nutrient agar enriched with 5% sheep blood) that encourages the growth of bacteria, such as Streptococci, that otherwise wouldn’t grow. Blood contains inhibitors for certain bacteria such as Neisseria and Haemophilus genera and the blood agar must be heated to inactivate these inhibitors and to release essential growth factors (e.g., V factor). Heating of blood agar converts it into chocolate agar (heated blood turns a chocolate color) and supports the growth of these bacteria. Comment Certain bacterial species produce extracellular enzymes that lyse red blood cells in the blood agar (hemolysis). These hemolysins (extotoxin) radially diffuses outwards from the colony (or colonies) causing complete or partial destruction of the red cells (RBC) in the medium and complete denaturation of hemoglobin within the cells to colorless products. There are different types of hemolysis which produced in sheep blood agar by Streptococci namely; alpha hemolysis, beta hemolysis and gamma hemolysis. Practice (10) Organism Colony color Type of hemolysis Greenish-grey or brownish Streptococcus pneumoniae Alpha hemolysis discoloration around the colony Complete lysis of red blood cells Streptococcus pyogenes Beta hemolysis causing a clearing of blood Complete lysis of red blood cells Staphylococcus aureus Beta hemolysis causing a clearing of blood Haemophilus influenzae Can not grow on this medium Negative No hemolysis of RBC. No change Klebsiella pneumoniae Gamma hemolysis of the medium 2) Antibiotic sensitivity test Procedure 1- Suspend 28 grams of nutrient agar in 1000 ml purified/distilled water. 2- Heat to boiling to dissolve the medium completely. 3- Sterilize by autoclaving at 1.5 atm (121°C) for 15 minutes. 4- Cool to 45-50°C. 5- The bacterial strains are added to the melted agar medium and mix gently but well and then pour the inoculated medium into sterile Petri dishes. Then, Leave the plates to solidify. 6- Cut circular holes into the agar by a corkborer. 2) Antibiotic sensitivity test Procedure 7- Add the solutions of the antibiotics into the holes separately. 8- Incubate at 37°C for 24-48 hrs. 9- After incubation period, examine the plates and write your observation. Observation After overnight incubation, Zones of inhibition (ZOI) are formed. The diameter of each zone should be measured and recorded in mm. Comment Antibiotics are types of antimicrobial substances produced by some microorganisms that kill or slow down the growth of bacteria. They include a range of powerful drugs and are used to treat diseases caused by bacteria. Antibiotics cannot treat viral infections, such as cold, flu, and most coughs. Antibiotics are powerful medicines that fight certain infections and can save lives when used properly. They either stop bacteria from reproducing or destroy them. Before bacteria can multiply and cause symptoms, the immune system can typically kill them. Comment White blood cells (WBCs) attack harmful bacteria and, even if symptoms do occur, the immune system can usually cope and fight off the infection. Sometimes, however, the number of harmful bacteria is excessive, and the immune system cannot fight them all. Antibiotics are useful in this case. The first antibiotic was penicillin which mainly produced by Penicillium notatum and P. chrysogenum. Comment Mode of action of antibiotics: 1- Penicillin: it prevents the formation of cell wall in susceptible bacteria. 2- Bacitracin is a peptide antibiotic and produced by Bacillus licheniformis. Its antimicrobial spectrum is against Gram-positive bacteria. It inhibits bacterial cell wall synthesis by inhibiting dephosphorylation of lipid pyrophosphate. 3- Streptomycin: it produced by Streptomyces griseus. Protein synthesis in a culture is inhibited at about the time that the vial count begins to decrease. Later, DNA and RNA synthesis and respiration are inhibited, and the cell membrane is damaged. 4- Erythromycin is an antibiotic produced by growth of certain strains of Streptomyces erythreus. It acts by inhibiting elongation at the transpeptidation step, specifically aminoacyl translocation from the A-site to P-site by binding to the 50s subunit of the bacterial 70s rRNA complex. This product acts against both Gram-negative and Gram- positive bacteria. Comment 5- Actinomycin D which produced by Streptomyces sp. inhibits the proliferation of cells by forming a stable complex with double-stranded DNA, inhibiting DNA-primed RNA synthesis and causing single-stranded breaks in DNA. It has been shown to be an inhibitor of the minus-strand transfer step in reverse transcriptase. 6- Chloramphenicol is isolated from Streptomyces venezuelae. It blocks the formation of peptide bonds on bacterial ribosomes and therefore inhibits protein synthesis. 7- Cyclosporin A is produced by Tolypocladium inflatum. It inhibits the T-cell receptor signal transduction pathway via the formation of cyclosporin A-cyclophilin complex that inhibits calcineurin (protein phosphatase 2B). Thank you .
Load more

Recommended publications
  • Tryptose Blood Agar Base
    Tryptose Blood Agar Base Intended Use Principles of the Procedure Tryptose Blood Agar Base is used with blood in isolating, Tryptose is the source of nitrogen, carbon and amino acids in cultivating and determining the hemolytic reactions of fastidi- Tryptose Blood Agar Base. Beef extract provides additional ous microorganisms. nitrogen. Sodium chloride maintains osmotic balance. Agar is the solidifying agent. Summary and Explanation Investigations of the nutritive properties of tryptose demon- Supplementation with 5-10% blood provides additional growth strated that culture media prepared with this peptone were factors for fastidious microorganisms and is used to determine superior to the meat infusion peptone media previously used hemolytic patterns of bacteria. for the cultivation of Brucella, streptococci, pneumococci, me- Formula ningococci and other fastidious bacteria. Casman1,2 reported Difco™ Tryptose Blood Agar Base that a medium consisting of 2% tryptose, 0.3% beef extract, Approximate Formula* Per Liter 0.5% NaCl, 1.5% agar and 0.03% dextrose equaled fresh beef Tryptose .................................................................... 10.0 g infusion base with respect to growth of organisms. The small Beef Extract ................................................................. 3.0 g amount of carbohydrate was noted to interfere with hemolytic Sodium Chloride ......................................................... 5.0 g Agar ......................................................................... 15.0 g reactions, unless the medium was incubated in an atmosphere *Adjusted and/or supplemented as required to meet performance criteria. of carbon dioxide. Tryptose Blood Agar Base is a nutritious infusion-free basal Directions for Preparation from medium typically supplemented with 5-10% sheep, rabbit or Dehydrated Product horse blood for use in isolating, cultivating and determining 1. Suspend 33 g of the powder in 1 L of purified water.
    [Show full text]
  • Laboratory Exercises in Microbiology: Discovering the Unseen World Through Hands-On Investigation
    City University of New York (CUNY) CUNY Academic Works Open Educational Resources Queensborough Community College 2016 Laboratory Exercises in Microbiology: Discovering the Unseen World Through Hands-On Investigation Joan Petersen CUNY Queensborough Community College Susan McLaughlin CUNY Queensborough Community College How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/qb_oers/16 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] Laboratory Exercises in Microbiology: Discovering the Unseen World through Hands-On Investigation By Dr. Susan McLaughlin & Dr. Joan Petersen Queensborough Community College Laboratory Exercises in Microbiology: Discovering the Unseen World through Hands-On Investigation Table of Contents Preface………………………………………………………………………………………i Acknowledgments…………………………………………………………………………..ii Microbiology Lab Safety Instructions…………………………………………………...... iii Lab 1. Introduction to Microscopy and Diversity of Cell Types……………………......... 1 Lab 2. Introduction to Aseptic Techniques and Growth Media………………………...... 19 Lab 3. Preparation of Bacterial Smears and Introduction to Staining…………………...... 37 Lab 4. Acid fast and Endospore Staining……………………………………………......... 49 Lab 5. Metabolic Activities of Bacteria…………………………………………….…....... 59 Lab 6. Dichotomous Keys……………………………………………………………......... 77 Lab 7. The Effect of Physical Factors on Microbial Growth……………………………... 85 Lab 8. Chemical Control of Microbial Growth—Disinfectants and Antibiotics…………. 99 Lab 9. The Microbiology of Milk and Food………………………………………………. 111 Lab 10. The Eukaryotes………………………………………………………………........ 123 Lab 11. Clinical Microbiology I; Anaerobic pathogens; Vectors of Infectious Disease….. 141 Lab 12. Clinical Microbiology II—Immunology and the Biolog System………………… 153 Lab 13. Putting it all Together: Case Studies in Microbiology…………………………… 163 Appendix I.
    [Show full text]
  • SHEEP BLOOD AGAR - for in Vitro Use Only - Catalogue No
    SHEEP BLOOD AGAR - For in vitro use only - Catalogue No. PS58 Our Sheep Blood Agar is a highly nutritious Interpretation of Results medium used for the cultivation and isolation of a variety of microorganisms. Sheep Blood Agar can be used as a primary- Our Sheep Blood Agar is based on the Oxoid plating medium. Primary isolation is performed to formulation; the prepared medium is said to offer separate and isolate organisms present in a sample. improved nutritional value resulting in better growth This separation allows for characterization of and larger colony size as well giving more colony types and may indicate the presence of consistent hemolytic reactions especially among the clinically significant bacteria. When examining streptococci. The base is specifically designed for plates a hand lens or stereoscopic microscope use with sheep blood as horse blood has shown to should be available for examining very small give different and conflicting hemolytic reactions colonies. The different types of colonial when incorporated into other blood agars. morphology appearing on the agar plate should be The nutritional components include pancreatic noted as well as the number of each morphotype digest of casein, neutralized peptone, and yeast present. Hemolysis is also a very useful differential extract, and the addition of sodium chloride characteristic that is best viewed when a bright light provides an osmotically balanced medium for is transmitted from behind the plate. Four different bacterial cells. The addition of 5% defibrinated types of hemolysis can be described: sheep blood allows for the determination of hemolytic reactions, an important differential 1. Alpha-hemolysis ( α) – Partial hemolysis that characteristic.
    [Show full text]
  • Screening for Asymptomatic Bacteriuria in Adults: an Updated Systematic Review for the U.S
    Evidence Synthesis Number 183 Screening for Asymptomatic Bacteriuria in Adults: An Updated Systematic Review for the U.S. Preventive Services Task Force Prepared for: Agency for Healthcare Research and Quality U.S. Department of Health and Human Services 5600 Fishers Lane Rockville, MD 20857 www.ahrq.gov Contract No. HHSA-290-2015-00007-I, Task Order No. 3 Prepared by: Kaiser Permanente Research Affiliates Evidence-based Practice Center Kaiser Permanente Center for Health Research Portland, OR Investigators: Jillian T. Henderson, PhD, MPH Elizabeth M. Webber, MS Sarah I. Bean, MPH AHRQ Publication No. 19-05252-EF-1 September 2019 This report is based on research conducted by the Kaiser Permanente Research Affiliates Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (HHSA-290-2015-00007-I, Task Order No. 3). The findings and conclusions in this document are those of the authors, who are responsible for its contents, and do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services. The information in this report is intended to help health care decision makers—patients and clinicians, health system leaders, and policymakers, among others—make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information (i.e., in the context of available resources and circumstances presented by individual patients).
    [Show full text]
  • Special Microbiology Practical Week 3. – STREPTOCOCCI Streptococci
    Special Microbiology practical week 3. – STREPTOCOCCI Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains. Older cultures may lose their Gram-positive character. Most streptococci are facultative anaerobes, and some are obligate (strict) anaerobes.Most require enriched media (blood agar). Streptococci are subdivided into groups by antibodies that recognize surface antigens These groups may include one or more species.Serologic grouping is based on antigenic differences in cell wall carbohydrates (groups A to V), in cell wall pili-associated protein, and in the polysaccharide capsule in group B streptococci.Rebecca Lancefield developed the serologic classification scheme in 1933. β-hemolyticstrains possess group- specific cell wall antigens, most of which are carbohydrates. These antigens can be detected by immunologic assays and have been useful for the rapid identification of some important streptococcal pathogens.The most important groupable streptococci are A, B and D. Among the groupable streptococci, infectious disease (particularly pharyngitis) is caused by group A. Group A streptococci have a hyaluronic acid capsule.Streptococcus pneumoniae(a major cause of human pneumonia) and Streptococcus mutansand other so-called viridans streptococci (among the causes of dental caries) do not possess group antigen.Streptococcus pneumoniaehas a polysaccharide capsulethat acts as a virulence factor for the organism,more than 90 different serotypesare known, and these types differ in virulence. Beta Hemolysis Streptococcus pyogenes, or Group A beta-hemolytic Streptococci (GAS), and Streptococcus agalactiae, or Group B beta-hemolytic Streptococci (GBS) blood agar cultures display beta hemolysis. Beta hemolysis (β-hemolysis), called complete hemolysis, is a complete lysisof red blood cells in the media around and under the colonies: the area appears lightened (yellow) and transparent.
    [Show full text]
  • Escherichia Coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Propertiesᰔ 1 2 1 2
    JOURNAL OF CLINICAL MICROBIOLOGY, July 2010, p. 2449–2458 Vol. 48, No. 7 0095-1137/10/$12.00 doi:10.1128/JCM.01611-09 Copyright © 2010, American Society for Microbiology. All Rights Reserved. Escherichia coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Propertiesᰔ 1 2 1 2 Rebecca E. Watts, Viktoria Hancock, Cheryl-Lynn Y. Ong, Rebecca Munk Vejborg, Downloaded from Amanda N. Mabbett,1 Makrina Totsika,1 David F. Looke,3 Graeme R. Nimmo,4 Per Klemm,2 and Mark A. Schembri1* School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia1; Microbial Adhesion Group, DTU Food, Technical University of Denmark, Lyngby, Denmark2; and Infection Management Services, Princess Alexandra Hospital,3 and Queensland Health Pathology Service, Department of Microbiology, Royal Brisbane and Women’s Hospital,4 Brisbane, Queensland, Australia Received 19 August 2009/Returned for modification 12 November 2009/Accepted 22 April 2010 http://jcm.asm.org/ Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli being responsible for >80% of all cases. Asymptomatic bacteriuria (ABU) occurs when bacteria colonize the urinary tract without causing clinical symptoms and can affect both catheterized patients (catheter- associated ABU [CA-ABU]) and noncatheterized patients. Here, we compared the virulence properties of a collection of ABU and CA-ABU nosocomial E. coli isolates in terms of antibiotic resistance, phylogenetic grouping, specific UTI-associated virulence genes, hemagglutination characteristics, and biofilm formation. CA-ABU isolates were similar to ABU isolates with regard to the majority of these characteristics; exceptions were that CA-ABU isolates had a higher prevalence of the polysaccharide capsule marker genes kpsMT II and on October 22, 2015 by University of Queensland Library kpsMT K1, while more ABU strains were capable of mannose-resistant hemagglutination.
    [Show full text]
  • Streptococci
    STREPTOCOCCI Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains. Older cultures may lose their Gram-positive character. Most streptococci are facultative anaerobes, and some are obligate (strict) anaerobes. Most require enriched media (blood agar). Streptococci are subdivided into groups by antibodies that recognize surface antigens (Fig. 11). These groups may include one or more species. Serologic grouping is based on antigenic differences in cell wall carbohydrates (groups A to V), in cell wall pili-associated protein, and in the polysaccharide capsule in group B streptococci. Rebecca Lancefield developed the serologic classification scheme in 1933. β-hemolytic strains possess group-specific cell wall antigens, most of which are carbohydrates. These antigens can be detected by immunologic assays and have been useful for the rapid identification of some important streptococcal pathogens. The most important groupable streptococci are A, B and D. Among the groupable streptococci, infectious disease (particularly pharyngitis) is caused by group A. Group A streptococci have a hyaluronic acid capsule. Streptococcus pneumoniae (a major cause of human pneumonia) and Streptococcus mutans and other so-called viridans streptococci (among the causes of dental caries) do not possess group antigen. Streptococcus pneumoniae has a polysaccharide capsule that acts as a virulence factor for the organism; more than 90 different serotypes are known, and these types differ in virulence. Fig. 1 Streptococci - clasiffication. Group A streptococci causes: Strep throat - a sore, red throat, sometimes with white spots on the tonsils Scarlet fever - an illness that follows strep throat. It causes a red rash on the body.
    [Show full text]
  • Inhibition of a Staphylococcal Hemolysin by a Soluble Substance Produced by a Nonhemolytic
    INHIBITION OF A STAPHYLOCOCCAL HEMOLYSIN BY A SOLUBLE SUBSTANCE PRODUCED BY A NONHEMOLYTIC MICROCOCCUS SPECIES PINGHUI LIU' Kitasato Institute for Infectious Diseases, Tokyo, Japan Received for publication June 2, 1954 Inhibition of the activity of a bacterial toxin usually grew into the line of micrococcus. The by antitoxic immune sera or by chemicals such as picture resembles those in an article published by formalin is commonly observed. The inhibition Elek and Levy (1950). The inhibition of hemolysis caused by metabolic products of other types of in their cases, however, was caused by specific bacteria, however, has never been described. The antihemolytic sera. In order to avoid the confu- present communication describes a preliminary sion with specific antisera which are often called observation of one such phenomenon. "antihemolysin", the soluble substance produced by the micrococcus will be referred to as "hemol- EXPERIMENTAL METHODS AND RESULTS ysin inhibiting substance" (HIS). A colony of a yellow pigment forming, non- Identification of the hemolysin inhibited by hemolytic Micrococcus species (tentatively identi- hemolysin inhibiting substance. It is well known fied as Micrococcus luteus) was found on a human that staphylococci from various sources produce blood agar plate close to a hemolytic staphylo- several different types of hemolysins (Glenny and coccal colony. It was also noted that the zone of Stevens, 1935; Smith and Price, 1938; Williams hemolysis of this Staphylococcus (the term and Harper, 1947). It was necessary to identify Micrococcus is not used here for this organism to the type of hemolysin concerned in this phe- avoid confusion with the other) was slightly but nomenon.
    [Show full text]
  • Clinical Medical Assistant
    Career Programs Clinical Medical Assistant Clemson University - Center for Corporate Learning 1 North Main Street, 7th Floor, Greenville, SC 29601 http://www.clemson.edu/online/ Contact: Juanita Durham│ 864.656.3984│[email protected] Clinical Medical Assistant Format: Self-Pace Online / eLearning Program Duration: 6 Months Course Contact Hours: 780 The Clinical Medical Assisting Profession The Clinical Medical Assisting program is designed to prepare students to function as professionals in multiple healthcare settings. Medical Assistants with a clinical background perform various clinical tasks including assisting with the administration of medications and with minor procedures, performing an EKG electrocardiogram, obtaining laboratory specimens for testing, educating patients, and other related tasks. Job opportunities are prevalent with physician’s offices, clinics, chiropractor’s offices, hospitals, and outpatient facilities. The Clinical Medical Assisting Program This program prepares students to assist physicians by performing functions related to the clinical aspects of a medical office. Instruction includes preparing patients for examination and treatment, routine laboratory procedures, pharmacology, taking and documenting vital signs, technical aspects of phlebotomy, the 12-lead EKG and the cardiac life cycle. Education and National Certifications • Students should have or be pursuing a high school diploma or GED. • There are no state approval and/or state requirements associated with this program. • National Certification: o
    [Show full text]
  • BD™ Columbia Agar with 5% Sheep Blood
    INSTRUCTIONS FOR USE – READY-TO-USE PLATED MEDIA PA-254005.06 Rev.: Apr 2013 BD Columbia Agar with 5% Sheep Blood INTENDED USE BD Columbia Agar with 5% Sheep Blood is a highly nutritious general purpose medium for the isolation and cultivation of nonfastidious and fastidious microorganisms from clinical specimens. PRINCIPLES AND EXPLANATION OF THE PROCEDURE Microbiological method. Ellner et al.1 in 1966 reported the development of a new blood agar formulation, which has been designated as Columbia Agar. BD Columbia Agar with 5% Sheep Blood derives its superior growth-supporting properties from the combination of two peptones, and yeast extract as a supplier of the B complex vitamins. Corn starch is included to absorb toxic by-products contained in the specimen and serves as an energy source for organisms possessing alpha- amylases. Sheep blood allows detection of hemolytic reactions and supplies the X factor (heme) necessary for the growth of many pathogenic species. On this medium, colonies tend to be larger and growth is more luxuriant than on media containing other blood agar bases. Columbia Blood Agar is recommended as a primary isolation medium in the MiQ standards and in other diagnostic manuals.2,3 In many European countries, this medium has become the most frequently used primary isolation medium for clinical specimens. REAGENTS BD Columbia Agar with 5% Sheep Blood Formula* Per Liter Purified Water Pancreatic Digest of Casein 12.0 g Peptic Digest of Animal Tissue 5.0 Yeast Extract 3.0 Beef Extract 3.0 Corn Starch 1.0 Sodium Chloride 5.0 Agar 13.5 Sheep Blood, Defibrinated 5 % pH 7.3 ± 0.2 *Adjusted and/or supplemented as required to meet performance criteria.
    [Show full text]
  • Staphylococci
    STAPHYLOCOCCI Staphylococci are typical Gram-positive bacteria forming irregular clusters of cocci. Staphylococci are widespread in nature, although they are mainly found on the skin, skin glands and mucous membranes of mammals and birds, but can cause infection under certain circumstances. 1S. aureus is more pathogenic than the other common members of the genus, S. epidermidis and S. saprophyticus. S. epidermidis has been known to cause various hospital-acquired infections (such as prosthetic or indwelling devices), whereas S. saprophyticus is mainly associated with urinary tract infections in young females who are sexually active. Disease processes with S. aureus are numerous. The portal of entry is variable, since they gain access to the body via the skin, the respiratory tract or the genito- urinary tract. Staphylococcus aureus expresses many potential virulence factors: 1. surface proteins - promote colonization of host tissues 2. leukocidin, kinases, hyaluronidase - invasins that promote bacterial spread in tissues 3. capsule, Protein A - surface factors that inhibit phagocytic engulfment 4. carotenoids, catalase - enhance staphylococcal survival in phagocytes 5. protein A, coagulase - immunological disguises 6. hemolysins, leukotoxin, leukocidin - membrane-damaging toxins that lyse eucaryotic cell membranes 7. 2TSST, 3ET - exotoxins that damage host tissues or otherwise provoke symptoms of disease 8. inherent and acquired resistance to antimicrobial agents. Fig. 1 Virulence determinants of Staphylococcus aureus. 1 S. - Staphylococcus 2 TSST - Toxic Shock Syndrome Toxin 3 ET - Exfoliatin Toxin Staphylococci can cause many forms of infection: 1. S. aureus causes superficial skin lesions (boils) and localized abscesses in other sites. 2. S. aureus causes deep-seated infections, such as osteomyelitis and endocarditis and more serious skin infections (furunculosis).
    [Show full text]
  • Preparation of the Blood-Enriched Agar with the Use of Red Cell Suspension
    Vol. 1 No. 1 January 2011 ISSN: 2094-9243 pp. 259-275 Asian Journal of Health International Peer Reviewed Journal Clinical Research Section doi: http://dx.doi.org/10.7828/ajoh.v1i1.168 Preparation of the Blood-Enriched Agar with the Use of Red Cell Suspension CARINA R. MAGBOJOS [email protected] RICHELLE S. ARO MA. CHARISMA S. CARINGAL MELVIN M. CASTILLO DARWIN A. LLANES KAREN D. SUMARAY Lyceum of the Philippines University - Batangas City Date Submitted: April 2, 2009 Plagiarism Detection: Passed Final Revision Complied: June 3, 2010 Flesch Reading Ease: 36.08 Gunning Fog Index: 13.11 Abstract - A culture medium is said to support the growth and development of different microorganisms. Certain bacteria like Staphylococcus aureus and Staphylococcus epidermidis entail hemoglobin found in the red blood cells. Because of its cost effectiveness and availability, expired human blood is being utilized in some developing countries. Despite the widely accepted disadvantages of using human blood as enrichment agent, many laboratories still opt to use it due to the unavailability of sheep blood or due to budgetary reasons. This study determined if the washed expired human blood can be used as an alternative enrichment agent in the preparation of Blood Agar Plate (BAP) culture medium in the isolation of Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 12228. The cultural characteristics and hemolytic reactions of the selected microorganisms were recorded, assessed and compared with their growth in BAP. The stability of the washed expired human blood was evaluated in terms of 259 Asian Journal of Health Clinical Research Section temperature and storage period.
    [Show full text]