Proper Specimen Collection Research Articles

Pseudoepidemic of urinary tract infections due to Trichosporon beigelii.

During the period April, 1985 to March, 1986, Trichosporon beigelii was isolated from the urine of 15 intensive care unit patients. All of these patients had Foley catheters in place at the time of T beigelii isolation. None of them had urinary tract infections on admission, and it was initially felt that this organism was a source of infection in these critically ill individuals. Subsequent investigation revealed this to be a pseudoepidemic secondary to contamination of the urinary catheter drainage system. Urine obtained by gravity drainage from the outlet port of urimeters yielded growth of T beigelii, whereas urines obtained concurrently from the proximal tubing sampling port were negative. T beigelii was isolated from the drainage port as well as from various items used in the collection and sampling of urine specimens. It is felt that these items were the source of perpetuation of this pseudoepidemic due to the repeated contamination and colonization of the distal portion of the urine catheter collection system. In-services to nursing and housekeeping personnel in the proper collection of urine specimens and cleaning of potentially contaminated items, the replacement of metal urine graduates with disposable plastic ones and increased monitoring of personnel's activities stopped the outbreak abruptly.

Fine structural features in tumor diagnosis

The primary objective in submitting a specimen to the electron microscopy laboratory is to obtain additional information about the tissue which is not readily available employing conventional light microscopic techniques. In order for this analysis to be meaningful every effort must be taken to assure that the tissue is observed with minimal alteration of its structural components. Tissue which has been frozen, embedded in paraffin or placed in standard laboratory formalin will seldom exhibit the structural fidelity needed to justify the time and expense of an electron microscopic examination. While there are numerous reports on how tissues processed in this manner can, as a last resort, be retrieved for diagnostic use I suggest that the better method is to educate your staff on the proper selection and collection of specimens for possible ultrastructural evaluation.

The Compromised Host: Quantitative Sputum Analysis with a Nontoxic Mucolytic Agent

Detoxified saponin (Solryth ™ ) has been found to be a stable, rapid and effective mucolytic agent which does not inhibit the growth of bacteria or fungi. In comparing quantitative sputum lysis using Solryth ™ with a conventional semiquantitative method, the former technique was found to yield more reproducible and less ambiguous results. For most potentially pathogenic organisms, a bacterial concentration of >10 7 colony-forming units (CFU) per milliliter of digested sputum is highly suggestive of infection in most cases. The data also suggest that the diagnostic threshold for lung infection caused by saprophytic species of Hemophilus appears to be >108/ml. The quantitative method has a 1.5% falsepositive rate (2/128 patients were positive for organisms which were not clinically significant) as compared to 48% (61/128) of the conventional cultures. The conventional and quantitative methods failed to recover a significant organism in nine and four cases, respectively. Regardless of the technique used, prior throat cultures, proper specimen collection, sputum grading and repeat specimens are necessary to obtain meaningful results.

The investigation of cryoglobulins

In recent years the discovery of cryoglobulins has become increasingly frequent in a wide variety of disease states including multiple myeloma, acute and chronic infections, and immune complex diseases. However, proper collection of specimens is essential for their detection. In our laboratory, 10 ml clotted blood and 10 ml oxalated blood are taken and kept at 37 C for at least 1 h before centrifugation and separation. This procedure is followed by incubation at 4 C for a minimum period of 3 days. Depending on the circumstances, identification and quantitation of the cryoprecipitate are carried out in the following order: (a) total protein and albumin estimation; (b) electrophoresis and quantitation of globulin fractions; (c) specific quantitations by radial immunodiffusion; (d) Immunoelectrophoresis; (e) serological investigations, particularly the estimation of rheumatoid factor. For an initial patient sample of 108, there were 11 occurrences of cryofibrinogen and 5 of cryoglobulins. Two cases of cryoglobulin of special interest have been found: (1) monoclonal cryoglobulin of lambda gamma type with massive crystalglobulinaemia and peripheral gangrene; and (2) mixed monoclonal/polyclonal cryoglobulin with a kappa mu paraprotein having strong rheumatoid factor activity which was undetected in serum unless cryoglobulin collection was done.

The Microbiology of Musculoskeletal Infection

Of paramount importance in the isolation and identification of bacteria, including mycobacteria, and fungi that cause musculoskeletal infections, are proper selection, collection, and transport of specimens. Material obtained by biopsy, curettage, or aspiration is preferable to that obtained on a swab because too little or unrepresentative material is usually collected on a swab and because swabs cannot be transported readily under conditions favorable to survival of anaerobes. Although actual infections are frequently due to staphylococci, strepococci, Enterobacteriaceae, and Pseudomonadacease, the etiologic agents of chronic lesions may include actinomycetes, brucellae, mycobacteria, and fungi. In chronic lesions, histopathologic examination of biopsy material is an important ancillary procedure. In acute infections, the incidence of gram-negative bacilli, particularly of Enterobacteriaceae and pseudomonads, has increased significantly in recent years.

THE DIAGNOSIS OF URINARY TRACT INFECTION

The mere presence (or absence) of any given microorganism is not adequate for ruling it in or out as a cause of clinical urologic infection. A distinction between true bacteriuria and contamination of the urine during the procedure of collection must always he made in the evaluation of a positive urine culture. The bacterial count in a given urine sample has offered a means of defining this distinction. The limited data in children, supported by more extensive data in adults, suggest that urines containing less than 1,000 colonies/ml are indicative of contamination; urines containing between 1,000 and 100,000 colonies/ml are to be suspected of infection and studies repeated, and urines containing more than 100,000 colonies/ml are indicative of infection. The proper collection and handling of specimens after collection is mandatory, and should not be entrusted to untrained personnel. Conditions under which low bacterial counts may be encountered in the presence of active infection are discussed. Special consideration must be given to those patients with chronic or recurrent urinary tract infection who frequently, in the presence or absence of symptoms, may show bacterial counts in the urine below the range considered to be significant. Reliable clinical means for resolving this problem remain to be explored. Suprapubic aspiration of bladder urine for culture and bacterial counts may prove helpful in given cases. Pyuria, said to be the hallmark of pyelonephritis, is not of itself satisfactory for making a diagnosis of urinary tract infection. In the first place, there is a lack of general agreement as to what constitutes pyuria; secondly, pyuria may be seen with many extra-renal infections; and finally, pyuria may be absent with infection of the urinary tract. A Gram stain of an uncentrifuged specimen of urine will usually reveal bacteria if infection is present. This has been subjected to quantitative evaluation, with almost all urine specimens with bacterial counts of 100,000 or more/ml showing organisms when stained by Gram's method. Thus, the Gram stain of a smear of urine provides a useful screening technique for detecting patients with urinary tract infection. While it has been taught, generally, that only the study of catheter specimens in girls is reliable for the diagnosis of urinary tract infection, recent studies refute this. While there is always a risk of introducing infection during the procedure of catheterization, this is minimal if proper precautions are exercised, and such fear should not interdict catheterization under certain circumstances which have been mentioned. While bacteriuria is not to be considered synonymous with pyelonephritis, several histologic studies (at necropsy, at nephrectomy, and after renal biopsy) show that bacteriuria is frequently associated with involvement of the renal parenchyma. While reliable clinical means of determining which of the patients with true bacteriuria have renal involvement are not presently available, prudence dictates that each case of bacteriuria be regarded as being associated with active renal disease, or very likely to become so. The staining characteristics of leukocytes excreted in pyelonephritis may be helpful in determining the presence of renal involvement; the leukocytes of patients with cystitis or urethritis apparently do not show the staining characteristics of those excreted in pyelonephritis. A wider use of this supravital staining technique is needed to elucidate further its usefulness. In addition, renal function studies and roentgenographic examinations may be helpful. Bacteriologic culture of renal tissue obtained by needle biopsy has not proved fruitful, in general. Histopathologic study of such tissue has proved more rewarding. The limitations of the renal biopsy technique by needle are in large measure due to the focal nature of pyelonephritis. While the open biopsy technique, permitting direct visualization of the kidney and selection of site(s) for biopsy, may provide more adequate tissue for examination than the blind needle technique, satisfactory comparative data are lacking.

A Comparison of the Quantitative Urinary Urobilinogen Determination (Watson) with the Urine Ehrlich Test

The quantitative determination of 24-hour urinary urobilinogen excretionl has been generally accepted as a reliable and sensitive indicator of liver dysfunction. The method, however, is time-consuming and tedious when the test is done on large numbers of patients. Its performance requires considerable laboratory equipment and the proper collection of 24-hour specimens is difficult. A simplified technic which reports urinary urobilinogen quantitatively in Ehrlich units has been described3, which largely eliminates the above objections. The latter is not specific, however, and includes in the color reaction other aldehyde reacting substances beside urobilinogen. The purpose of this study was to compare the accuracy of the two methods to ascertain whether the simplified urine Ehrlich test as performed in the prescribed manner is reliable as a screening procedure for the more difficult 24hour quantitative procedure.