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The stability of the CSF sample varies depending on the procedures ordered. Cell counts are ALWAYS STAT and should be performed within 30 - 60 minutes for best results. Samples should be left at room temperature for no longer than one hour and refrigerated following testing. Refrigeration is not recommended for culture specimens since fastidious organisms such as Haemophilus influenzae and Neisseria meningitidis may not survive the cold temperature.

The urine specimen should be freshly voided. Urine is an ideal medium for the proliferation of bacteria due to the large amount of urea present. These bacteria metabolize urea, producing ammonia that increases the urine pH. If there is a delay before performance of the test, the sample should be refrigerated. This will: Prevent urease-producing organisms, such as Proteus and Pseudomonas, from converting urine urea to ammonia, which results in an increased pH. Prevent loss of CO2 which increases pH to the alkaline range.The "run-over" phenomenon may occur if excess urine remains on the strip. The protein area, adjacent to the pH area, contains an acid buffer which may "run-over" the pH portion resulting in an acid reading on a neutral or alkaline urine.

Illustrated is the picture of the surface of a disk diffusion test including a ceftazidime disk (left) and a combintation ceftazidime/clavulanic acid disk (right).Observe in the photograph that the zone of inhibition around the the combination ceftazidime/clavulanic acid disk (right) is at least 5 mm larger than around the clavulanic acid disk (left).This observation that the presence of clavulanic acid, a beta-lactamase inhibitor, has resulted in such a large increase in the zone of inhibition indicates that an extended spectrum beta lactamase (ESBL)is being produced.When an organism is producing an ESBL, the susceptibility to individual cephalosporins cannot be predicted, thus requiring that each drug must be tested individually.It may be important to detect ESBL-producing stains of K. pneumoniae and E. coli as treatment failure may occur if the wrong cephalosporin is selected.

Suppola JP. Kuikka A. Vaara M. Valtonen VV. Comparison of risk factors and outcome in patients with Enterococcus faecalis vs Enterococcus faecium bacteremia. Scandinavian Journal of Infectious Diseases. 30(2):153-7, 1998.The purpose of our study was to determine retrospectively the risk factors for the acquisition of Enterococcus faecalis vs E. faecium bacteremia, as well as the clinical outcomes of these patients.62 patients with Enterococcus faecalis bacteremia were compared to 31 patients with E. faecium bacteremia. Haematologic malignancies, neutropenia, high-risk source and previous use of aminoglycosides, carbapenems, cephalosporins and clindamycin were significantly associated with E. faecium bacteremia. Instead, urinary catheterization was found to be related to Enterococcus faecalis bacteremia. The mortality rates within 7 d and 30 d were 13% and 27%, respectively, in patients with E. faecalis bacteremia and 6% and 29%, respectively, in patients with E. faecium bacteremia.There was no difference in mortality between E. faecalis and E. faecium bacteremia, nor was there a difference in seriousness of disease at the time of bacteremia. In the subgroups of patients with monomicrobial or clinically significant E. faecalis vs E. faecium bacteremia, the mortality rates were similar to the results of all subjects.Our results do not support the theory that E. faecium would be a more virulent organism than E. faecalis

Lorimer JW. Eidus LB.: Invasive Clostridium septicum infection in association with colorectal carcinoma. Canadian Journal of Surgery. 37:245-9, 1994The association between invasive Clostridium septicum infection and colorectal carcinoma is examined by the presentation of three cases and a review of the literature.In the first two cases the patients presented with nontraumatic metastatic clostridial gas gangrene.In the third case a patient with chemotherapy-induced myelosuppression from concomitant multiple myeloma had a necrotizing transmural infection of the right colon.The apparent portal of entry of Clostridium septicum was an occult carcinoma of the ascending colon. The increasing evidence for a strong link between this organism and some cases of neutropenic enterocolitis is reviewed.

Spencer RC.: Invasive streptococcEuropean Journal of Clinical Microbiology & Infectious Diseases. 14 Suppl. 1:S26-32, 1995.Before the introduction of antibiotics, serious infections caused by Streptococcus pyogenes (Lancefield Group A streptococci) were common. Before World War II, this bacterium was responsible for as many as 50% of postpartum deaths and was the major cause of death in patients with burns. Also common were the sequelae of streptococcal infections-rheumatic fever and post-streptococcal glomerulonephritis.With the use of penicillin, however, Streptococcus pyogenes was believed to be virtually eliminated as a pathogen. The organism was consigned to the history books, but not for long.In the mid-1980s, focal resurgences of rheumatic fever began to be reported from different areas in the USA, such as Salt Lake City, Utah. In such communities, where increases in cases of rheumatic fever had been reported, the serotypes M-1, 3, 5, 6 and 18 were isolated which, on culture, produced characteristic mucoid colonies. At the same time, reports of increases in invasive streptococcal disease began to surface in both the USA and Europe.Two syndromes were described; invasive streptococcal infection, occurring in previously healthy children and adults, commonly associated with septicaemia resulting from a deep focus of infection such as bone or lung; and streptococcal toxic shock syndrome, involving a cutaneous focus, accompanied by necrotizing or bullous soft tissue changes. Septicaemia is rare in streptococcal toxic shock syndrome, but the most characteristic feature is one of rapidly progressing multi-organ failure. A high proportion of the strains of Streptococcus pyogenes associated with this condition are serotype M-1, and fatality rates approaching 50% have been reported.

Biological agents are organisms or toxins that can kill or incapacitate people, live stock, and crops. The three basic groups of biological agents that would likely be used as weapons are bacteria, viruses, and toxins. Biological agents can be dispersed as aerosols or airborne particles.

Specialists in microbiology perform testing to diagnose and stop the spread of infectious organisms, including bacteria, viruses, and parasites. Specialists should be able to isolate and identify a wide variety of these organisms. Testing procedures include direction examination and antigen detection methods. Specialists in serology and immunology measure antibodies to infectious organisms. Specialists should be familiar with all serology techniques (except those specific to immunohematology). This specialty includes all lab procedures performed in the specialty of histocompatibility. Specialists in hematology must be able to identify and evaluate cells in blood and bone marrow and identify disorders of these cell. Specialists should be familiar with routine and special tests to determine the number, morphology, and function of cells in body fluid.

Cellular immunity includes delayed hypersentivity reactions, graft rejection, graft-versus-host reactions, defense against intracellular organisms, and probably defense against neoplasms.Cellular immunity is mediated by lymphocytes which we call T-cells.T-cells are so named because they are dependent on the thymus for their production and development.The majority of T-cells are long-lived with an average lifespan of 4.4 years, but it is known that some survive for as long as 20 years or more.T-cells are capable of leaving and re-entering the circulation many times during their long life.T and B cells cannot be differentiated when viewing blood films.They are identified through the use of immunologic cell markers.

As a healthcare worker, you come into contact with bloodborne pathogens. These are infectious organisms, usually viruses, which live in human blood and other potentially infectious body fluids.The most important ones are... Hepatitis B Virus (HBV) Human Immunodeficiency Virus (HIV)

This phlebotomist violated hospital procedures in several ways that could adversely impact patient care: Cleaning the site only with alcohol, not iodine, could result in a false-positive contaminated blood culture. This might result in the patient receiving unnecessary intravenous antibiotics, and could prolong the patients hospital stay unnecessarily. Drawing both cultures at the same time lessens the chance of recovering a bloodstream organism.Drawing both cultures from the same site might result in both of them being contaminated, making it very difficult for the physician to distinguish contamination from a “real” bloodstream infection.Relevant topics:Blood cultures: introduction, Avoid skin contamination, Blood culture site preparation 1, Blood culture site preparation 2

Blood is normally sterile. Any bacterial growth in the bloodstream is abnormal, and is an important cause of fever.Blood culture means the incubation of blood in appropriate media to allow growth and identification of bacteria or other organisms that may be present in a patient’s bloodstream. Blood cultures are performed on febrile patients to identify and treat bloodborne organisms with the most appropriate antibiotic.

The Gram stain reaction, shape, and arrangement of bacteria, and the presence or absence of intracellular organisms must be noted on the worksheet.Examples:Gram positive cocci in chains are present.Gram negative diplococci, intracellular, are present within white blood cells.Quantitate by approximating the average number of each cell type seen in 10 oil immersion fields, and record as:Many = More than 15/fieldModerate = 4-15/fieldFew = 1-3/fieldOccasional = 2-10/10 fieldsRare = 0-2/10 fields

Contamination of the staining solutions rarely occurs, but should be suspected when smears repeatedly contain the same organisms, and these organisms do not grow or are inconsistent with the clinical picture. Yeast and gram negative rods can occur as stain contaminants.

The ends of rod-shaped organisms may be rounded or tapered.

The following information is reported:Gram stain reactionShapeThe cellular arrangement is not usually included in the report because it may vary, depending on the culture medium (liquid or solid) from which the organism was taken.

Bacteria may also be present, especially during a urinary tract infection. This view shows bacteria as solid gray rods or cocci. Since bacteria may also be a contaminant in specimens remaining at room temperature, or due to an unclean catch, caution must be observed in reporting bacteria. If 20 organisms per hpf are seen, the bacteria are considered to be clinically significant.

The natural history of TB infection is usually followed by an immune response and latency after exposure. In about 5-10% of cases, the latent period progresses to an active infection.The organism that causes TB infection is Mycobacterium tuberculosis. This organism is pictured in the photograph to the right as observed when stained with acridine orange stain. Infection occurs when a susceptible person inhales droplet nuclei containing Mycobacterium tuberculosis and the organism reaches the alveoli of the lungs.About 2-12 weeks after infection, the immune system limits multiplication of additional bacteria and the immunological test becomes positive.Latent tuberculosis infection (LTBI) is the stage when the viable organism remains in the body, and the patient has no symptoms and is non-infectious.Most infected persons do not experience clinical illness and are noninfectious. About 5-10% of persons infected with Mycobacterium tuberculosis who are not treated will develop TB during their lifetime. The risk for progression is highest during the first several years after infection.TB infects the lungs most often; however, it can infect almost any organ in the body, including bones and joints.