Culture Information and Courses from MediaLab, Inc.

The samples from each tube are used for specific tests:The first tube may also be used for serological testing.The second tube is used for gram stain and culture.The third tube is used for the cell count and differential.The fourth tube is used for cytological examinations or other tests which may be needed to further characterize abnormal cells.

The nitrites portion of the reagent strip provides a rapid screening test for the presence of gram-negative bacteria that are often responsible for urinary tract infections. Although urine cultures are still needed to confirm the diagnosis and monitor any urinary tract or kidney infection, the need for a culture may not be obvious because in some cases of early bladder infection, the symptoms may be vague or the patient may be asymptomatic. Diagnosis and treatment of cystitis (bladder infection) is important because if left untreated it may result in kidney damage, impairment of renal function, hypertension and/or septicemia.

A 67 year-old man entered the hospital with cough, right lower chest pain accentuated by deep breathing, and fever. He had a history of chronic obstructive pulmonary disease secondary to a long history of smoking. The temperature on admission was 39.2C, and auscultation of the chest revealed rales in the right lower lung field. The admission white blood count was 13,500/ml with 80% segmented neutrophils and a shift to the left. A blood culture was obtained.

A 72- year old woman had a history of recurrent urinary tract infections over the past several months, for which she had received different regimens of antibiotics including ampicillin, trimethoprim-sulfasoxazole, and ciprofloxacin.Relapses often occurred 10 days to two weeks after cessation of therapy.The current flare up, manifest by dysuria, lower abdominal pain and cloudy urine was accompanied by shaking chills and spiking fever.A sterile mid-stream urine specimen was sent to the laboratory for culture.

In follow up to the previous question, the upper image again illustrates the colonies recovered from the blood culture bottle. The colonies are small, transluscent, gray-yellow, and surrounded by a wide zone of beta hemolysis.The size of the colonies compared to the zones of hemolysis suggests a group A streptococcus.The susceptibility to bacitracin (zone of inhibition around the "A" disk)(lower photograph) is virtually diagnostic of a group A streptococcus.The absence of a zone of inhibition around the SXT disk indicates resitance to sulfamethoxazole/ trimethoprim. SXT resistance is also shared by group B streptococci, which are, however, resistant to bacitracin.The resistance to SXT is used for the primary recovery of groups A and B streptococci from specimens with mixed culture. Their resistance allows them to selectively grow out from contaminating bacteria that are inhibited by this antibiotic.

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.

A 35 year old man presented in the emergency room with an erythematous, vesiculo-pustular lesion of the arm near the elbow (see photograph). One week previously he had scratched his arm on the aerial of his car while washing the windshield. He noticed a red area about 3 days after the incident, which then spread to involve the adjacent tissue. The central pustule developed on the day he was seen. Material from the center of the pustule was sent to the microbiology laboratory for culture.

Molecular methodologies offer numerous advantages to the clinical laboratory. These include:Sensitivity: Amplification methodologies are particularly useful in increasing the sensitivity of a methodology and useful in the identification of target molecules of interest that are only present in low concentrations. Specificity: Molecular methods minimize false positive test results by targeting the specific molecule of interest.Turn Around Time: In comparison with standard traditional culture methods, molecular methodologies usually offer better turn around times from receipt to result reporting.Application: broader application can be found with molecular methodologies such as infectious diseases, genetic testing, forensics, drug resistance, and tumor marker detection and monitoring.

Examining the biopsy allows the structure of the marrow to be viewed as it exists in the body. It provides essential diagnostic information in conditions that disrupt the normal architecture, such as metastatic carcinoma, myelofibrosis, Hodgkin's lymphoma and granuloma. A biopsy may also be used to evaluate cellularity and identify acid-fast bacteria or fungi in less time than is needed for routine culture methods. One disadvantage of the tissue sections prepared from the biopsy sample is that morphologic detail is lost. For this reason, in many cases imprint slides or smears from the aspirated sample are also examined.

Specialists in cytogenetics detect chromosome abnormalities and genetic disorders. Cytogenetics counseling may only be performed by an individual licenses in the cytogenetics specialty at the director level. Specialists in molecular genetics analyze DNA and RNA to find disease-related genotypes, mutations, and phenotypes in order to detect or predict disease and identify carriers. Specialists in histocompatibility test to determine tissue compatibility, prevent infections, and investigate and post-transplant problems. Techniques include blood typing, HLA typing, HLA antibody screening, disease markers, flow cytometry, crossmatching, HLA antibody identification, lymphocyte immunophenotyping, immunosuppressive drug assays, allogenic, isogeneic and autologous bone marrow processing and storage, mixed lymphocyte culture, stem cell culture, cell mediated assays, and assays for the presence of cytokines. Specialists in andrology and embryology examine gametes and embryos, including production, morphology, number, and motility, to address issues of fertility and infertility.

People tend to look for someone to blame when medical mistakes occur. Victims and their loved ones find some satisfaction in blaming. An environment of blame encourages a culture of secrecy about medical mistakes. Mandatory reporting laws have not overcome this secrecy, and they do not encourage efforts to find ways of avoiding errors. Error reduction requires a commitment from the healthcare community to recognize and acknowledge that medical errors indicate systems problems, not people problems.

A phlebotomist from the laboratory at Midtown Memorial Hospital was working evening shift. Her shift ended at 11 PM and it was 10:30 PM. She suddenly got orders for a STAT blood culture on the second floor. The order specified blood culture times two, 30 minutes apart. The phlebotomist went to the patient’s room and decided to collect both blood cultures at the same time form the same site so she would be able to leave on time without having to come back in thirty minutes to collect the second set. She also wanted to “save” the patient from an extra stick. While the phlebotomist was preparing for the collection, she realized she didn’t have any Betadine on her tray, and decided she would just clean the site twice with alcohol. She finished the blood culture collections and was able to leave by 11 PM.

Contain either acid citrate dextrose (ACD), which maintains RBC viability and may be used for HLA phenotyping, DNA, paternity testing, or lymphocyte surface markers, or: Sodium polyanetholesulfonate (SPS) which is sometimes used to collect blood culture specimens.

A blood transfer device allows the transfer of blood from a syringe into a blood collection tube or a blood culture bottle. The BD™ blood transfer device is shown here.

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.

Normal skin is not sterile – it contains numerous bacteria.These normal skin bacteria can contaminate a blood culture, causing a false-positive blood culture result.Thorough decontamination of the skin puncture site is therefore essential prior to obtaining the blood culture specimen.

Clean blood culture bottles while the iodine on the venipuncture site is drying. Wipe the tops of the blood culture bottles, first with a new iodine swab, then with a clean alcohol pad.

After collecting the blood, activate the needle safety device according to manufacturer’s instructions, and place it in a sharps disposal container. If blood was collected into a syringe, insert the syringe tip into the hub of a blood transfer device, and rotate the syringe clockwise to secure it to the device. Push the blood culture bottle into the holder of the transfer device, and draw the appropriate volume of blood into the blood culture bottles.

An experienced phlebotomist should be knowledgeable in the collection of: - Venous blood specimens - Capillary blood specimens - Blood culture specimens - Urine specimens - Throat cultures, and - Medico legal specimens requiring chain of custody. He or she should also know how to: - Process specimens - Perform bleeding times, and - Collection specimens from IV lines and central venous lines, under appropriate supervision.

A direct smear is made from a clinical specimen, not a culture. It can be used to:Guide the physician on initial choice of antibiotic, pending results of culture and sensitivity.Judge specimen quality.Contribute to selection of culture media, especially with mixed flora.Provide internal quality control when direct smear results are compared to culture results.

Identification of bacteria in direct smears may be of lifesaving importance. For example, a rapid diagnosis of bacterial meningitis, made after examining a gram stained smear of the patient's cerebrospinal fluid, allows the physician to begin treatment immediately.The appearance of bacteria on gram stained smears is suggestive of a certain species, but identification may not be made on the basis of the stain alone. An exception to this rule is the presence of gram negative intracellular diplococci from a male urogenital specimen, which is presumptive identification of Niesseria gonorrhoeae.In addition, culture results can be correlated with the direct smear report.

It is important to note the Gram stain reaction, shape, and cellular arrangement when examining culture smears. This information may be useful to the physician in making a presumptive identification.

The culture smear is used to determine the staining characteristic and shape of the unknown organism since this data helps the microbiologist to decide on additional culture and identification methods. By correlating the Gram stain reaction, colony morphology and growth requirements, the microbiologist may be able to tentatively identify the organism, which the physician may use to modify treatment, until definitive culture and antibiotic susceptibility results become available.

The process of culture, isolation and identification of microorganisms is basic to medical microbiology. When a culture shows signs of growth, the process of identification includes examining the following characteristics:appearance of the colonies in the culture mediumstaining reactionappearance of stained organismssizeshapearrangement of bacterial cellsThis type of preliminary identification may help the physician to initiate the appropriate antibiotic treatment.

In order to test collection containers for sperm collection, the sperm must be held in the container for several hours to ensure that neither the numbers nor motility are adversely affected. Numbers will decline if the sperm adhere to the container. Motility will decline if the container is toxic. One method of testing involves removing sperm from semen. The specimen would be centrifuged and the sperm pellet diluted in a small volume of culture medium containing an energy source and at least 0.5% of a protein, such as serum albumin. The processed sperm specimen would be placed in the container to be tested. Total count and motility of the sperm would be tested at the start of incubation and 24 hours later. The container is non-toxic if the motility at the end of 24 hours is no less than 50% of the original value.