This book makes the vast and complex field of medical microbiology more accessible by the use of four-color graphics and numerous illustrations with detailed. Color Atlas of Diagnostic Microbiology - Free ebook download as PDF File .pdf) or read book online for free. Title: When the Moon Split: A biography of Prophet Muhammad (Peace be upon him) Author: Safiur-Rahman al-Mubarkpuri Subj.
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Request PDF on ResearchGate | On Jan 1, , W.C. Winn and others published Color Atlas an Textbook of Diagnostic Microbiology. editions of Microbiology Laboratory Theory and Application, one edition of Microbiology When we did the first edition, the Atlas broke the mold at Morton Publishing by including with the brown color (due to bismuth sulfite reduction) . Some Drugs and Herbal Products. RCS66 World Health. Organization,. International. Agency for. Research on. Cancer. USMLE® step 1.
When covering a particular type of media or biochemical reaction, the authors include a brief explanation of the principle of the test or media. The accompanying photographs depict positive and negative reactions; these photos are clear and feature easy-to-distinguish reactions. However, some of the photographs of colony morphology can be difficult to visualize.
For example, some bacteria with small colonies that are opaque or light gray can be hard to distinguish on the agar surface.
It would have been beneficial if the authors had included magnified images to attempt to visualize some of the finer details of individual colony-forming units. Also, it was sometimes difficult to visualize zones of inhibition in certain photographs of susceptibility-testing photographs.
Another key feature of this text is its incorporation of tables of growth characteristics, or positive biochemical reactions for commonly used tests, which help the laboratory professional distinguish between related genera eg, positive urease reactions among Enterobacteriaceae.
Photographs of positive biochemical reactions often are found later within the chapters that are referenced in the tables.
The two new chapters ie, 38 and 39 are placed at the end of the book. Chapter 38 covers antimicrobial susceptibility testing AST.
The authors discuss the performance of AST; however, much of the chapter relates to how certain methodologies can help the laboratorian detect resistant phenotypes of clinically important species related to infection control activities eg, use of the modified Hodge test for carbapenemase production in Enterobacteriaceae or use of the D test for inducible clindamycin resistance among Staphylococcus aureus specimens. Chapter 39 examines the present state of the microbiology lab and recognizes that the most frustrating aspect of working in this department is the amount of time it takes to deliver results to the health care professional.
The illustrations depicting the assay characteristics and principles are colorful and easy to understand. Overall, this book is rich in high-quality photographs of Gram stains, colony morphology, and biochemical test results and reactions used to identify clinically important species of bacteria. Diagnostic medical microbiology is the discipline that identifies etiologic agents of disease.
The job of the clinical microbiology laboratory is to test specimens from patients for microorganisms that are, or may be, a cause of the illness and to provide information when appropriate about the in vitro activity of antimicrobial drugs against the microorganisms identified Fig.
Figure Laboratory procedures used in confirming a clinical diagnosis of infectious disease with a bacterial etiology. The staff of a clinical microbiology laboratory should be qualified to advise the physician as well as process specimens. The physician should supply salient information about the patient, such as age and sex, tentative diagnosis or details of the clinical syndrome, date of onset, significant exposures, prior antibiotic therapy, immunologic status, and underlying conditions.
The clinical microbiologist participates in decisions regarding the microbiologic diagnostic studies to be performed, the type and timing of specimens to be collected, and the conditions for their transportation and storage.
Above all, the clinical microbiology laboratory, whenever appropriate, should provide an interpretation of laboratory results. Manifestations of Infection The manifestations of an infection depend on many factors, including the site of acquisition or entry of the microorganism; organ or system tropisms of the microorganism; microbial virulence; the age, sex, and immunologic status of the patient; underlying diseases or conditions; and the presence of implanted prosthetic devices or materials.
The signs and symptoms of infection may be localized, or they may be systemic, with fever, chills, and hypotension. In some instances the manifestations of an infection are sufficiently characteristic to suggest the diagnosis; however, they are often nonspecific. Microbial Causes of Infection Infections may be caused by bacteria including mycobacteria, chlamydiae, mycoplasmas, and rickettsiae , viruses, fungi, or parasites. Infection may be endogenous or exogenous. In endogenous infections, the microorganism usually a bacterium is a component of the patientapos;s indigenous flora.
Endogenous infections can occur when the microorganism is aspirated from the upper to the lower respiratory tract or when it penetrates the skin or mucosal barrier as a result of trauma or surgery. In contrast, in exogenous infections, the microorganism is acquired from the environment e. Although it is important to establish the cause of an infection, the differential diagnosis is based on a careful history, physical examination, and appropriate radiographic and laboratory studies, including the selection of appropriate specimens for microbiologic examination.
Results of the history, physical examination, and radiographic and laboratory studies allow the physician to request tests for the microorganisms most likely to be the cause of the infection. Specimen Selection, Collection and Processing Specimens selected for microbiologic examination should reflect the disease process and be collected in sufficient quantity to allow complete microbiologic examination.
The number of microorganisms per milliliter of a body fluid or per gram of tissue is highly variable, ranging from less than 1 to or colony-forming units CFU.
Swabs, although popular for specimen collection, frequently yield too small a specimen for accurate microbiologic examination and should be used only to collect material from the skin and mucous membranes. Because skin and mucous membranes have a large and diverse indigenous flora, every effort must be made to minimize specimen contamination during collection. Contamination may be avoided by various means. The skin can be disinfected before aspirating or incising a lesion.
Alternatively, the contaminated area may be bypassed altogether. Examples of such approaches are transtracheal puncture with aspiration of lower respiratory secretions or suprapubic bladder puncture with aspiration of urine.
It is often impossible to collect an uncontaminated specimen, and decontamination procedures, cultures on selective media, or quantitative cultures must be used see above.
Specimens collected by invasive techniques, particularly those obtained intraoperatively, require special attention. Enough tissue must be obtained for both histopathologic and microbiologic examination. Histopathologic examination is used to distinguish neoplastic from inflammatory lesions and acute from chronic inflammations. The type of inflammation present can guide the type of microbiologic examination performed.
If, for example, a caseous granuloma is observed histopathologically, microbiologic examination should include cultures for mycobacteria and fungi. The surgeon should obtain several samples for examination from a single large lesion or from each of several smaller lesions.
If an abscess is found, the surgeon should collect several milliliters of pus, as well as a portion of the wall of the abscess, for microbiologic examination. Swabs should be kept out of the operating room. If possible, specimens should be collected before the administration of antibiotics. Above all, close communication between the clinician and the microbiologist is essential to ensure that appropriate specimens are selected and collected and that they are appropriately examined.
Microbiologic Examination Direct Examination Direct examination of specimens frequently provides the most rapid indication of microbial infection. A variety of microscopic, immunologic, and hybridization techniques have been developed for rapid diagnosis Table Sensitivity and Specificity The sensitivity of a technique usually depends on the number of microorganisms in the specimen.
Its specificity depends on how morphologically unique a specific microorganism appears microscopically or how specific the antibody or genetic probe is for that genus or species. The sensitivity of the Gram-stained smear for detecting Gram-negative coccobacilli in cerebrospinal fluid from children with Haemophilus influenzae meningitis is approximately 75 percent because in some patients the number of colony-forming units per milliliter of cerebrospinal fluid is less than At least CFU of tubercle bacilli per milliliter of sputum must be present to be detected by an acid-fast smear of decontaminated and concentrated sputum.
An increase in the sensitivity of a test is often accompanied by a decrease in specificity. For example, examination of a Gram-stained smear of sputum from a patient with pneumococcal pneumonia is highly sensitive but also highly nonspecific if the criterion for defining a positive test is the presence of any Gram-positive cocci. If, however, a positive test is defined as the presence of a preponderance of Gram-positive, lancet-shaped diplococci, the test becomes highly specific but has a sensitivity of only about 50 percent.
Similar problems related to the number of microorganisms present affect the sensitivity of immunoassays and genetic probes for bacteria, chlamydiae, fungi and viruses. In some instances, the sensitivity of direct examination tests can be improved by collecting a better specimen. For example, the sensitivity of fluorescent antibody stain for Chlamydia trachomatis is higher when endocervical cells are obtained with a cytobrush than with a swab.
The sensitivity may also be affected by the stage of the disease at which the specimen is collected. For example, the detection of herpes simplex virus by immunofluorescence, immunoassay, or culture is highest when specimens from lesions in the vesicular stage of infection are examined.
Finally, sensitivity may be improved through the use of an enrichment or enhancement step in which microbial or genetic replication occurs to the point at which a detection method can be applied.
Techniques For microscopic examination it is sufficient to have a compound binocular microscope equipped with low-power 1OX , high-power 40X , and oil immersion 1OOX achromatic objectives, 10X wide-field oculars, a mechanical stage, a substage condenser, and a good light source.
For examination of wet-mount preparations, a darkfield condenser or condenser and objectives for phase contrast increases image contrast. An exciter barrier filter, darkfield condenser, and ultraviolet light source are required for fluorescence microscopy. For immunologic detection of microbial antigens, latex particle agglutination, coagglutination, and enzyme-linked immunosorbent assay ELISA are the most frequently used techniques in the clinical laboratory.
Antibody to a specific antigen is bound to latex particles or to a heat-killed and treated protein A-rich strain of Staphylococcus aureus to produce agglutination Fig. There are several approaches to ELISA; the one most frequently used for the detection of microbial antigens uses an antigen-specific antibody that is fixed to a solid phase, which may be a latex or metal bead or the inside surface of a well in a plastic tray.
Antigen present in the specimen binds to the antibody as in Fig. The test is then completed by adding a second antigen-specific antibody bound to an enzyme that can react with a substrate to produce a colored product.
The initial antigen antibody complex forms in a manner similar to that shown in Figure When the enzyme-conjugated antibody is added, it binds to previously unbound antigenic sites, and the antigen is, in effect, sandwiched between the solid phase and the enzyme-conjugated antibody. The reaction is completed by adding the enzyme substrate. Figure Agglutination test in which inert particles latex beads or heat-killed S aureus Cowan 1 strain with protein A are coated with antibody to any of a variety of antigens and then used to detect the antigen in specimens or in isolated bacteria.
Once such a unique nucleotide sequence, which may represent a portion of a virulence gene or of chromosomal DNA, is found, it is isolated and inserted into a cloning vector plasmid , which is then transformed into Escherichia coli to produce multiple copies of the probe. The sequence is then reisolated from plasmids and labeled with an isotope or substrate for diagnostic use. The use of molecular technology in the diagnoses of infectious diseases has been further enhanced by the introduction of gene amplication techniques, such as the polymerase chain reaction PCR in which DNA polymerase is able to copy a strand of DNA by elongating complementary strands of DNA that have been initiated from a pair of closely spaced oligonucleotide primers.
This approach has had major applications in the detection of infections due to microorganisms that are difficult to culture e. Culture In many instances, the cause of an infection is confirmed by isolating and culturing microorganism either in artificial media or in a living host. Bacteria including mycobacteria and mycoplasmas and fungi are cultured in either liquid broth or on solid agar artificial media.
Liquid media provide greater sensitivity for the isolation of small numbers of microorganisms; however, identification of mixed cultures growing in liquid media requires subculture onto solid media so that isolated colonies can be processed separately for identification. Growth in liquid media also cannot ordinarily be quantitated.
Solid media, although somewhat less sensitive than liquid media, provide isolated colonies that can be quantified if necessary and identified.
Some genera and species can be recognized on the basis of their colony morphologies. In some instances one can take advantage of differential carbohydrate fermentation capabilities of microorganisms by incorporating one or more carbohydrates in the medium along with a suitable pH indicator.
Such media are called differential media e. Different genera of the Enterobacteriaceae can then be presumptively identified by the color as well as the morphology of colonies. Culture media can also be made selective by incorporating compounds such as antimicrobial agents that inhibit the indigenous flora while permitting growth of specific microorganisms resistant to these inhibitors. One such example is Thayer-Martin medium, which is used to isolate Neisseria gonorrhoeae.
This medium contains vancomycin to inhibit Gram-positive bacteria, colistin to inhibit most Gram-negative bacilli, trimethoprim-sulfamethoxazole to inhibit Proteus species and other species that are not inhibited by colistin and anisomycin to inhibit fungi.
The pathogenic Neisseria species, N gonorrhoeae and N meningitidis, are ordinarily resistant to the concentrations of these antimicrobial agents in the medium. The number of bacteria in specimens may be used to define the presence of infection. For this reason, quantitative cultures Fig.