Improve microbiology procedures and utilization - while saving money.

Thoughtful cost-cutting can provide opportunities to upgrade equipment and update protocols. Enlist your medical staff's cooperation through well-planned communication.

When the federal government implemented diagnosis related groups (DRGs) in 1983 to reimburse hospitals for Medicare and Medicaid services, reimbursement was suddenly based on discharge diagnosis rather than on medical care costs generated by the patient.[1] Since that time, insurance companies increasingly have adopted contracts similar to DRGs to control costs. Insurers also have made certain that any hospital lacking a vast number of Medicaid and Medicare patients use some sort of prospective payment system (PPS) or reimbursement plan.

Managed care, lab consolidations, and hospital mergers are forcing hospital labs to become cost-effective without sacrificing quality.[2] It has become obvious the prompt release of lab results can help reduce hospital costs under DRG/PPS arrangements. The clinical laboratory can implement cost savings by improving physicians' utilization of the lab and by modifying test procedures.

For example, cytocentrifugation of specimens for Gram-stain and acid-fast (AF) smears might be introduced inexpensively to provide faster, more sensitive results. Because microbiology labs are less automated and more labor-intensive than chemistry and hematology labs, microbiologists must find new methods to improve and accelerate current test procedures, even under increasing budgetary constraints.

Public pressure and changing health care needs have forced the lab to use allocated resources more efficiently. In fact, decreasing patient census has led many small community hospitals to use reference labs for low-volume routine assays.

Small hospital labs, for instance, can contain costs significantly by eliminating unnecessary tests and sending out specimens received for testing of acid-fast bacilli (AFB). When test results are crucial components of patient care, however, and turnaround time (TAT) must be kept to a minimum, a hospital lab may have to perform some preliminary tests on site - even if they are not cost-effective.

On-site testing of urgent procedures provides crucial support to the critically ill patient in a timely fashion, thereby reducing morbidity and associated costs. Many strategies can be used to improve lab utilization.

OPTIMIZING LAB UTILIZATION

Physicians tend to overutilize, underutilize, or misutilize laboratory resources. A laboratory is underutilized when relevant microbiology tests are not ordered. Laboratory resources are overutilized when irrelevant tests are ordered. Lab data are misutilized when significant microbiology test results are ignored.[2]

Since all cost-generating procedures originate with a physician's order, it's important to devise written guidelines for educating the medical staff.[3] One way to improve laboratory utilization is to make physicians aware of the operating schedule established for each laboratory section. Laboratory timetables for assay testing should be made known to all medical staff members who may order routine microbiology tests.

Perhaps the lab testing schedule should be modified to match physicians' needs as well. Physicians should be told the costs incurred for each laboratory test performed, the limitations assigned to microbiology orders, and the extent of diagnostic testing. For example, a laboratory utilization plan might call for sharing with all staff physicians in a hospital newsletter or memorandum the information listed in Figure 1.

Laboratory utilization can be improved by soliciting the support of infectious disease physicians, hospital pharmacists, and the chief of medicine. Certain policies are discussed most effectively at medical staff meetings. Such policies include the number of specimens accepted per individual site and the expected TAT for microbiology test results. Physicians should be told changes in lab protocol are based on data, opinions, and ideas published in reputable literature, with careful consideration given to suggestions by respected experts.

BETTER MICROSCOPIC EXAMS

The introduction of cytocentrifugation techniques in the microbiology lab has enhanced microscopic examinations in recent years. Cytocentrifugation has been used for a long time in hematology and cytology labs for analyzing cell morphologies in specimens of low volume. Using cytocentrifugation in microbiology was first reported as an aid in screening urines by Gram stain.

Spinal fluid Gram stains prepared by cytocentrifugation show an increased sensitivity of up to two logs compared with conventional centrifuge- prepared smears. Cytospin-prepared examinations are excellent screening procedures that should be given high priority in the clinical laboratory. When Gram stains, wet preparations, or AFB smears are performed and reported within one to two hours upon receipt, they can provide rapid preliminary findings that, in turn, will help physicians to determine the most likely etiologic agent of disease.

Cytocentrifuged smear results can be used to establish if a specimen represents a site of inflammation and infection. Clinicians can consider rapid microscopic results either to exclude or to establish a diagnosis or prognosis as well as to select the best therapy or monitor antibiotic therapy. On the other hand, delay of Gram stain/AF smear results compromises both patient care and employee safety.

BETTER CYTOCENTRIFUGATION

If smears are not received along with tests being ordered, then specimens received in transport swabs can best be Gram-stained by preparing smears through cytocentrifugation ([ILLUSTRATION FOE FIGURE 2 OMITTED] for a step-by-step illustration). Cytospun preparations show more bacteria with better cellular morphology than conventionally prepared smears. In our clinical laboratory, we have obtained excellent results by using the procedure that follows:

* Have the specimen collected with a dual Culturette-EZ swab (Becton Dickinson, Cockeysville, Md.). Emulsify one of the swabs in 1-2 mL of physiologic saline and vortex it yew gently. If the suspension still remains viscous, then dilute the specimen with extra saline.

* Using a disposable Cytopad Chamber (Wescore Inc., Logan, Utah) in a biosafety class II hood, add from 50-100 [[micro]liter] of suspension. Cap chamber and cytocentrifuge the mixture at 2,000 RPM for 5 minutes.

* Fix the smear on a heat block at 65[degrees]C until dry.

* Prepare a Gram stain using a conventional method.

* In a lab report, specify the amount and type of cells identified as well as the predominant organism that is being observed per oil power field.

FASTER URINE RESULTS

A review of the literature shows that cytospin-prepared Gram stains are an extremely sensitive screening method (98%), with a high specificity rate (90%) in detecting bacterial growth at 100,000 or more colony-forming units per mL. The bulleted list of instructional information that follows represents a modification of the procedure that was published a few years ago by Olson and his colleagues[4]:

* Mix urine specimens thoroughly.

* Add 50-100 [[micro]liter] of urine to a disposable Cytopad Chamber under a biosafety class II hood.

* Next, cap chamber and cytocentrifuge specimens at 2,000 RPM for 5 minutes.

* Fix smears on a heat block at a temperature of 65 [degrees]C until dry.

* Perform a Gram stain using a conventional method.

* Report a positive smear when a predominant organism is seen in 6 or more of 12 oil power fields. Report a negative smear when no bacteria are seen in any of the 12 fields or when few organisms are seen in less than 6 oil power fields.

BETTER AFB SMEARS

According to recommendations by the CDC and CAP requirements, fluorescent AF smear results must be available 24 hours after specimen collection. Also, as part of a complete tuberculosis exposure plan, AFB smear results should be available seven days a week.

Figure 3 describes a modification of the procedure[5] that can be adopted for reporting AFB smears before referring a sputum specimen to an outside lab or for pooling such specimens. Under a class II biosafety hood, aliquot a small amount of sputum into a sterile tube. Preferably, two specimens should be requested, one of which should be used for a bleached preparation as follows:

* Add an equal volume of 5% bleach. Incubate the mixture at room temperature for 5 minutes.

* If the suspension remains viscous, add physiologic saline.

* Add 50-100 [[micro]liter] of suspension to each of two disposable Cytopad Chambers.

* Next, cap chamber and cytocentrifuge specimens at 2,000 RPM for 5 minutes.

* Fix smears on a heat block at 65[degrees]C until dry.

* Prepare phenolic acidine orange fluorescent stain for mycobacteria as shown in Figure 4.

Cytocentrifuging specimens for AFB smears has advantages. First, safety is increased during specimen processing since the bleached preparation does not contain viable organisms. Also, results are available 20-30 minutes after receipt. Third, the procedure is simple, cost-effective, and can be used around the clock.

A NEED FOR SPEED

Under DRGs and PPS, physicians must establish a patient's infectious disease diagnosis swiftly to minimize hospital stay. While a rapid diagnosis can reduce hospital cost, a delayed diagnosis of infectious disease has negative financial effects on the lab.

With antibiotic resistance on the rise, diagnosing tuberculosis has become crucial. It is the responsibility of the microbiology department to find more sensitive testing methods to help deliver accurate information to the clinician a lot sooner. Speed can be increased by cytocentrifuging specimens for Gram stains and AFB smears. Sensitivity can be enhanced by staining AFB smears using the acridine orange fluorescent method.

Analyzing the TAT of final test result reports can help determine how efficiently specimens are being tested in a microbiology laboratory. One effective way to establish TAT is to assign a continuous quality improvement team to analyze discharge dates and the number of final reports that are sent to the medical records department rather than to the nursing unit in which the specimens originated. Sending final reports to the medical records department is done only for accountability because the opportunity to have the physician read your final reports, while the patient is still in the hospital, is drastically reduced.

The urgency to produce rapid microbiology results ultimately benefits our patients, who deserve appropriate, timely treatment. Patients whose AFB smears are positive can be placed in isolation promptly when results are available rapidly, on site, and around the clock. Providing preliminary reports more quickly and decreasing the TAT of Gram-stain results can help determine or exclude a diagnosis earlier in the process. Improving microscopic procedures by cytocentrifugation and staining methods enhances laboratory results and patient care.

References

1. Becker BL. The impact of DRGs after year 1: First steps toward greater lab efficiency. MLO. 1984; 16: 32-38.

2. Robinson A. Rationale for cost-effective laboratory medicine. Clin Microbiol Rev. 1994; 7: 185-199.

3. Axt-Adam P, Van Der Wouden JC, Van Der Does E. Influencing behavior of physicians ordering laboratory tests: A literature study. Med Care. 1993; 31: 784-794.

4. Olson ML, Shanholtzer CJ, Willark KE, Peterson LR. The slide centrifuge Gram stain as a urine screening method. Am J Clin Pathol. 1991; 96: 454-458.

5. Saceanu CA, Pfeiffer NC, McLean T. Evaluation of sputum smears concentrated by cytocentrifugation for detection of acid-fast bacilli. J Clin Microbiol. 1993; 31: 2,371-2,374.

6. Ellner PD. Cost-containment strategies for the diagnostic microbiology laboratory. Clin Microbiol Newsletter. 1987; 9: 117.

7. Siegel DL, Edelstein PH, Nachamkin I. Inappropriate testing for diarrheal diseases in the hospital. JAMA. 1990; 263: 979-982.

8. Aldeen WE, Whisenant J, Hale D, Matsen J, Carroll K. Comparison of pooled formalin-preserved fecal specimens with three individual samples for detection of intestinal parasites. J Clin Microbiol. 1993; 31: 144-145.

9. Archer GL. Coagulase-negative staphylococci in blood cultures; the clinician's dilemma. Infect Control. 1985; 6: 477-478.

10. Edberg SC, Trepeta RW. Rapid and economical identification and antimicrobial susceptibility test methodology for urinary tract pathogens. J Clin Microbiol. 1983; 18: 1,287-1,291.

11. National Committee for Clinical Laboratory Standards. Methods for Dilution Antimicrobial Susceptibility Testing for Bacteria that Grow Aerobically. Approved Standard M7-A3, 1993, Villanova, Pa: National Committee for Clinical Laboratory Standards.

12. National Committee for Clinical Laboratory Standards. Performance Standards for Antimicrobial Disk Susceptibility Test. Approved standard M2-A5, 1993. Villanova, Pa: National Committee for Clinical Laboratory Standards.

13. Jorgensen JH. Selection of antimicrobial agents for routine testing in clinical microbiology laboratory. Diagn Microbiol Infect Dis. 1993; 16: 245-249.

14. Ronald WS, Malcolm RB, Robert BF, Michael AK, Carolyn KW. Phenolic acridine orange fluorescent stain for Mycobacteria. J Clin Microbiol. 1995; 33: 2,763-2,764.

RELATED ARTICLE: Figure 1

Information for staff physicians regarding lab protocols

I. Specimen selection or processing measures.

A. Specimens unacceptable for culture:[6]

1. Foley catheter tip cultures.

2. Anaerobic cultures from vagina or cervic, bowel contents, or oral sources.

3. Surface cultures of decubiti.

4. Sputum showing oropharyngeal contamination by Gram stain.

B. Gram stains or other direct visual examination can yield sufficient diagnostic information without the need for culture.

1. Cultures are unnecessary if a 10% potassium hydroxide (KOH) preparation is positive for yeast from patient suspected of candidal vaginitis or from child or immunocompromised patient suspected of having thrush.

2. The presence of clue cells, lack of lactobacilli, increased pH, and disagreeable odor of vaginal discharge is indicative of bacterial vaginosis (nonspecific vaginitis), which precludes the necessity for culture.

C. Routine fecal cultures are limited to Campylobacter, Salmonella, and Shigella for patients hospitalized for [less than or equal to] 3 days and to outpatients.[7]

1. Diarrhea due to community-acquired pathogens generally is evident on admission or within the first three days.

2. Diarrhea that develops while patient is still in the hospital is likely to be caused by Clostridium difficile.

D. Ova and parasite exams are limited to patients hospitalized [less than or equal to] 3 days and to outpatients.

E. Multiple specimens from the same site are pooled and treated as a single specimen or single referral to an outside laboratory, for example:

1. Pooling of several formalin-preserved fecal specimens from the same patient before ova and parasite exam. Exception: patients suspected of Giardia or immunocompromised patients.[8]

2. Pooling multiple respiratory specimens for mycology. A 10% KOH or calcofluor white preparation is performed upon receipt.

3. Pooling multiple respiratory specimens for mycobacteriology. Cytospin-bleached-prepared smears for acid-fast bacilli performed upon receipt of each specimen.

F. Only two to three blood culture sets are needed to diagnose bacteremia if high volume samples are obtained. Excessive and solitary blood cultures are discouraged. 1 set = 2 bottles with 10 mL blood/bottle (20 mL/culture).

II. Limited workup on organisms unlikely to be clinically significant.

A. Organisms consistent with normal skin flora isolated from one of two or more blood specimens.

Exception: coagulase-negative staphylococci isolated from patients with catheter-related bacteremia.[9]

B. Urine or superficial would cultures yielding more than three species; organisms saved for one week.[10]

III. Selective reporting of antimicrobial susceptibility test results.[11-13]

A. Staphylococcus antibiogram reduced to penicillin and oxacillin. Antibiotic susceptibility or resistance can be deduced as follows:

1. Oxacillin-resistant strains are resistant to all current beta lactams.

2. Penicillin-resistant, oxacillin-susceptible strains are susceptible to beta-lactamase stable penicillins, inhibitor combinations, carbapenems, and most cephalosporins.

3. Penicillin-susceptible strains are susceptible to other beta lactams.

B. Routine testing or redundant drugs will be avoided, for example:

1. Routine testing of both cefotaxime and ceftriaxone.

2. Routine testing of erythromycin, azithromycin, and clarithromycin against pneumococci (only testing erythromycin).

3. Third-generation cephalosporins, reported if enteric isolate is resistant to first- and second-generation cephalosporins.

4. Amikacin reported only if an enteric organism is gentamicin-resistant.

5. Rifampin tested only when staphylococci are resistant to six [[micro]gram]/ml oxacillin in 4% NaCl Mueller-Hinto agar screen plate.

6. Penicillin, ceftriaxone, or cefotaxime minimum inhibitory concentration (MIC) performed only for Streptococcus pneumoniae resistant to [[micro]gram] oxacillin disk on Mueller-Hinton sheep blood agar.

RELATED ARTICLE: Figure 4

Phenolic acridine orange fluorescent stain for mycobacteria[14]

I. Preparation of stock solutions

A recent CDC study reports phenolic acridine orange fluorescent stain (PAOFS) is better than the traditional auramine O method. Research of the PAOFS method resulted in less nonspecific fluorescence and better contrasting background fluorescence when reading AFB smears.

A. Acridine orange stock reagent [A]: Prepare in dark-brown, one-gallon container.

1. Dissolve 50 g of phenol crystal (Fisher Scientific, Pittsburgh, Pa.) in a solution containing 500 mL distilled water, 250 mL glycerol (J.T. Baker, Philippsburg, N.J.), and 250 mL 95% ethanol (Midwest Grain Products, Pekin, Ill.).

2. Add 1 g of acridine orange 80% (uv-vis) (acros, Fairlong, N.J.).

3. Set overnight and keep at room temperature. Stir before using. Stock is good for six months.

B. Acid-alcohol destaining stock solution [B]: Prepare in one-gallon container.

1. Mix 740 mL of 95% ethanol, 260 mL deionized water, 5 mL concentrated hydrochloric acid (HCL) (Fisher Scientific, Pittsburgh, Pa.), and 2 g of methylene blue (Sigma, St. Louis, Mo.).

2. Keep at room temperature. Stir before use. Stock is good for six months.

II. Staining procedure

A. Prepare working solutions by dispensing stock A and B above into two 250 mL dark-brown squeeze bottles, respectively. Store in the dark at room temperature.

1. Heat-fix smears.

2. Cover entire specimen and quality control smears with acridine orange staining reagent A.

3. Set at room temperature for 15 minutes.

4. Rinse with water and drain.

5. Cover specimen and control smears with acid-alcohol destaining solution B.

6. Set at room temperature for two minutes.

7. Rinse with water, drain, and air dry. Do not blot

8. Read smears using a fluorescent microscope with a 100 W mercury vapor lamp. Screen smears using a scanning magnification of X200 and confirm morphology at X600. Thirty X200 fields should be observed before a smear is reported as negative.

9. Smears that cannot be read immediately should be refrigerated.

Faon Rodriguez is microbiology supervisor at Cape Canaveral Hospital, Cocoa Beach, Fla., and a microbiologist at Princeton Hospital, Orlando, Fla.