Responsible reporting in microbiology: Improving quality of care through better communication.

One of the most important functions that a microbiologist performs is to decide what is clinically relevant regarding specimen work-up, what organisms to look for and report, what organisms are pathogenic, and what constitutes normal flora. The microbiologist should make every effort to make a positive contribution to patient management by providing straightforward, uncluttered, and easy-to-understand reports. (1)

Communication between clinician and microbiologist is the most effective means of preventing inappropriate use of microbiology information. Addressing common communication errors between the medical staff and the microbiology laboratory and suggesting improvements in reporting practices is the focus of this article.

Inadequate reporting may lead to unnecessary action: Case study 1

A 30-month-old infant was U-bagged for a urine culture. No urinalysis was ordered or performed. Culture results were reported out as 2,000 col/mL (two colonies grew out on blood agar plate) of Pseudomonas aeruginosa. The clinician admitted the patient to pediatrics and started her on IV ceftazidime. When the clinician called the microbiology lab requesting susceptibilities, the urine sample was retrieved and urinalysis performed with normal results, even though urinalysis had not been ordered. How could communication between microbiology and the clinician have been improved? Perhaps by adding a comment to the culture results:

* "No urinalysis requested. Unable to determine significance of this isolate."

or

* "U-bag urine samples are unacceptable specimens for culture due to contamination from fecal and/or skin flora."

Reporting without a comment may lead to inappropriate antimicrobial therapy: Case study 2

Candida glabrata was identified and reported from two sets of blood cultures from a patient with systemic candidiasis. The patient was administered fluconazole for 10 days at which time the patient expired. Subsequently, the isolate was forwarded to a reference lab for antifungal minimum inhibitory concentrations (MICs), which confirmed that the isolate was resistant to fluconazole. How could communication between the microbiology laboratory and the clinician have been improved?

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* By adding a comment to the report:

** "Candida glabrata recovered. (Most C glabrata isolates are resistant to fluconazole therapy. Fungal susceptibilities available on request.)" (2)

The Gram-stain interpretation

The medical staff needs the laboratorian's help; make the Gram stain report useful. It is important to convey to the clinician what, if any, potential pathogen is present to provide an early indication of the cause of infection for administration of appropriate antibiotics. The presumptive interpretation of a microorganism is more useful than a description of the morphology, such as Gram-negative pleomorphic coccobacilli. Adding the comment "presumptive Haemophilus influenzae" is much more helpful.

* Do not report Gram-positive cocci in pairs and lancets from a sputum Gram stain. Report out Gram-positive cocci (e.g., "suspect Streptococcus pneumoniae"). If it looks like S pneumoniae on the slide, say it. S pneumoniae is extremely fastidious and may be seen on the Gram smear but may not always grow. So, if it is seen on the slide but the culture is negative, make note of it. (3)

* When interpreting a sputum Gram stain, place importance only on the predominant organism associated with polymorphonuclear (PMN) leukocytes.

* Bacteria seen in a Gram stain should be reported presumptively on the basis of microscopic morphology, e.g.:

** "Gram-positive cocci resembling Streptococcus pneumoniae from sputum";

** "Gram-positive cocci in clusters (presumptive Staphylococcus)";

** "Gram-positive cocci in chains (presumptive Streptococcus)";

** "Small Gram-negative coccobacilli in sputum (presumptive Haemophilus)"; or

** "Mixed flora."

Sputum cultures--lower respiratory tract

The culture of lower respiratory tract specimens may result in more unnecessary microbiologic effort than any other type of specimen. (4) The goal of clinical laboratories is to eliminate sputum cultures as much as possible because they typically are not useful. Only accept for culture those specimens with less than 10 squamous epithelial cells/LPF. (5) If the specimen is rejected, cancel the culture and bill for the Gram stain. Do not request another specimen, because it will probably be unacceptable as well.

* Sputum with <25 squamous epithelial cells/low power field (SEC/LPF) had cultures that correlated with transtracheal aspiration cultures 79% of the time, whereas a potential pathogen isolated from sputa with <10 SEC/LPF was 94% predictive of growth in the corresponding transtracheal aspirate. (6) Importantly, Gram-stained smears meeting the <10 SEC/LPF acceptance criteria can predict the etiological agent in pneumonias--documented by recovery from positive blood cultures. (7, 8)

* Do not work up yeast from a sputum culture. Candida pneumonia is extremely rare and diagnosis should be made by histopathological invasion and/or positive blood cultures. (9) Play down its importance in the culture work-up by calling it "yeast" rather than giving it a specific identification. An exception may be to perform a rapid urease to rule out Cryptococcus ssp. (10)

* Use comments when reporting unusual pathogens (e.g., sputum culture results: "Many Corynebacterium striatum recovered--predominant organism." This organism has been increasingly reported as the etiologic agent of various human infections, including bacteremic and fatal pleuropulmonary infections.) (11)

Female genital cultures

* The flora of the female genital tract varies with pH and estrogen concentration of the mucosa, which depend on the host's age. Work-up and reporting of organisms indigenous to the female genital tract (e.g., Enterobacteriacea, group B streptococci in nonpregnancy, non-group A beta streptococci) may suggest to the physician that the organism is causing an infection because the laboratory provided an identification and susceptibility-test result. Moreover, antibiotic treatment of any component of the normal vaginal flora may actually lead to overgrowth of Candida species and candidal vulvovaginitis. (12)

* Do not rely on culture for Gardnerella to diagnose bacterial vaginosis (BV). Reporting all isolates of Gardnerella from vaginal cultures is misleading since 50% to 90% of sexually active, asymptomatic women are colonized with this organism. A properly examined Gram smear should strongly suggest (or rule out) the diagnosis of BV. (13)

* About 3% to 10% of premenopausal females are vaginally colonized with Staphylococcus aureus. If S aureus is reported out from a genital culture, include the comment: "Patients colonized with this organism are at greater risk of developing toxic shock syndrome if they are tampon users." (14) Do not perform susceptibilities. The organism is colonizing the genital tract, not invading healthy tissue.

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Throat cultures

* The majority (80%) of cases of pharyngitis are caused by viruses, whereas 15% to 20% are caused by group A streptococci (Streptococcus pyogenes), the only cause of pharyngitis for which antimicrobial therapy is clearly indicated. (15)

* Except for the well-documented historic role of H influenzae as a cause of epiglottitis, there is no scientific evidence that H influenzae, S pneumoniae, or S aureus causes sore throat. Moreover, colonization of the pharynx with S aureus and enteric bacilli increases after antibiotic therapy. (16)

* Do not perform routine throat cultures. Perform organism-specific testing (e.g., throat culture for Neisseria gonorrhoeae, throat culture for yeast, or throat culture for Arcanobacterium haemolyticum). If a throat culture is ordered specifically (a written request for full throat culture), report the presence or absence of group A streptococci and A haemolyticum.

Throat cultures--First, do no harm

** If methicillin-resistant S aureas (MRSA) is reported out, other than a screen for carriage, the patient will be prescribed IV vancomycin.

** If Neisseria meningitidis is reported out, it is likely that the clinician will perform a lumbar puncture.

** If H influenzae is reported out, it is likely that the patient will be prescribed amoxacillin/clavulanate. (17)

** Recovery of S aureus, H influenzae, enterics, S pneumoniae, and other bacteria in cases of acute pharyngitis most likely means there is an underlying viral infection.

Nasopharyngeal (NP) cultures--Why do them?

* As many as 75% of healthy individuals harbor S pneumoniae and H influenzae in the upper respiratory tract.

* As many as 50% of healthy individuals harbor Moraxella catarrhalis in the upper respiratory tract.

* As many as 90% of healthy individuals harbor S aureus in the upper respiratory tract.

* When NP cultures from patients <12 years old grow S pneumoniae, H influenzae, or M catarrhalis, add the following comment: "Nasopharyngeal culture should not be used for the microbiological diagnosis of otitis media because of the high prevalence of asymptomatic carriage of this organism. Tympanocentesis is the recommended procedure for collecting specimens that will yield reliable microbiological results to guide therapy in otitis media." (18)

* NP cultures for N meningitidis: "Prophylaxis should be based on recent epidemiological exposure, not NP culture."

Blood cultures

* The use of antibiotic removal devices only adds confusion. If a patient has been started on antibiotics and follow-up blood cultures are drawn with antibiotic removal devices (resin), they may become positive--which the clinicians may interpret as meaning that the antibiotic the patient is on is not working. In addition, more coagulase-negative staphylococcal contaminants may be detected in media containing resins and activated charcoal than in media without these additives. (19)

* Add a comment to a presumptive contaminant to eliminate unnecessary antimicrobial therapy and lengthened hospital stays: "Susceptibilities will not be performed because the clinical significance of coagulase-negative staphylococci (or Bacillus ssp., diphtheroids, Corynebacterium, Propionibacterium ssp.) isolated from a single blood culture is undetermined. Please consult microbiology if further work-up is needed."

Stool cultures

* The cost of performing a stool examination on every patient for all potential pathogens is prohibitive. It is particularly important to quickly identify those cases of diarrheal disease caused by agents that require prompt therapy, other than oral rehydration, in order to be effective.

* As a general rule, primary culture media should provide for adequate recovery of Salmonella, Shigella, Campylobacter ssp., and Escherichia coli 0157:H7. The media selected should also be adequate to recover less-common enteric pathogens, such as Yersinia enterocolitica, Plesiomonas shigelloides, and Aeromonas species (e.g., blood agar).

* It is incorrect to issue a report "no enteric pathogens isolated"; rather, the report should state "culture negative for Salmonella, Shigella, Campylobacter, and E.coli 0157:H7," if these are the agents that are routinely looked for in a stool specimen. Also provide comments when reporting out uncommon agents of diarrheal illness: e.g., "Plesiomonas shigelloides isolated--this organism is associated with diarrheal illness that is usually self-limiting. Antimicrobial therapy may be indicated in severe or prolonged gastroenteritis. Contact microbiology if susceptibility studies are needed." (20)

Comment for E coli 0157:H7

Antimicrobial agents should not routinely be used to treat gastroenteritis due to E.coli 0157:H7 because they may increase the risk of hemolytic uremic syndrome. Antimicrobial agents do not accelerate recovery. (21)

Urine cultures

Urinary tract infection is one of the most commonly encountered acute infectious diseases and accounts for the majority of the workload in clinical microbiology laboratories. Because of the large workload, aggressive and unnecessary work-up of what often are insignificant organisms can waste laboratory resources, confound the physician, and ultimately result in unnecessary antimicrobial therapy, which leads to resistance.

Rule 1: Routine handling of a urine specimen for culture should include determination of the presence or absence of pyuria by the leukocyte esterase (LE) test or microscopic urinalysis. Since urinary tract infections (UTIs) are very rare in the absence of pyuria, urine cultures can be restricted to specimens that are LE-positive or show >5 white blood cells on urinalysis. (22) With the advent of computer-generated laboratory reports, instant availability of the urinalysis result can provide useful information to guide accurate culture work-up and appropriate antimicrobial-susceptibility testing.

Rule 2: Add comments to unusual microorganisms: e.g., ">100,000 col/mL Corynebacterium urealyticum. (This organism is an etiologic agent involved in alkaline-encrusted cystitis, a severe UTI that is difficult to treat. Because the organism is highly resistant to most antimicrobial agents, vancomycin is recommended. See patient's urine pH = 8.5.)" (23)

Take an active role; make a difference

A microbiologist's role is significant because he produces so much of the information that is used to make medical decisions. It is, therefore, important that his reports are readable, accurate, and credible. He is the expert, and both physicians and patients rely on him.

References

1. Lee A, McLean S. The laboratory report: a problem in communication between clinician and microbiologist? Med J Aust. 1977;2:858-860.

2. Nguyen MH, Peacock JE Jr, Morris AJ, et al. The changing face of candidemia: emergence of non-Candida albicans species and antifungal resistance. Am J Med. 1996;100:617-623.

3. Bartlett RC, Mazens-Sullivan MF, Lerer TJ. Differentiation of Enterobacteriaceae, Pseudomonas aeruginosa, and Bacteroides and Haemophilus species in Gram-stained direct smears. Diagn Microbiol Infect Dis. 1991;14:195-201.

4. Bartlett RC. Medical Microbiology: Quality, Cost, and Clinical Relevance. New York, NY: John Wiley and Sons, Inc.; 1974.

5. Sharp SE, ed. Cumitech 7B--Lower Respiratory Tract Infections. Washington, DC: ASM Press; 2004.

6. Geckler RW, Gremillion DH, McAllister CK, Ellenbogen C. Microscopic and bacteriological comparison of paired sputa and transtracheal aspirates. J Clin Microbiol. 1977;6:396-399.

7. Gleckman R, DeVita J, Hibert D, Pelletier C, Martin R. Sputum Gram stain assessment in community-acquired bacteremic pneumonia. J Clin Microbiol. 1988;26:846-849.

8. Potgieter PD, Hammond JM, Etiology and diagnosis of pneumonia requiring ICU admission. Chest. 1992; 101:199-203.

9. McAdams HP, Rosado-de-Christenson ML, Templeton PA, et al. Thoracic mycoses from opportunistic fungi: radiologic-pathologic correlation. Radiographics. 1995;15:271-286.

10. Forbes BA, Sahm DF, Weissfeld AS. Bailey and Scott's Diagnostic Microbiology. 11th ed. St. Louis, MO: Mosby; 2002:784.

11. Martinez-Martinez L, Suarez AI, Ortega MC, et al. Fatal pulmonary infection caused by Corynebacterium striatum. Clin Infect Dis. 1994;19:806-807.

12. Gorbach SL. IDCP Guidelines: Vaginitis, Infect Dis Clin Pract. 1997;6:284-290.

13. Nugent RP, Krohn MA, Hillier SL. Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation, J Clin Microbiol. 1991;29:297-301.

14. Shands KN, Schmid GP, Dan BB, et al., Toxic-shock syndrome in menstruating women: association with tampon use and Staphylococcus aureus and clinical features in 52 cases. N Engl J Med. 1980;303:1436-1442.

15. Bisno AL, Gerber MA, Gwaltney JM Jr, Kaplan EL, Schwartz RH. Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. Clin Infect Dis. 2002;35:113-125.

16. Gwaltney JM Jr, Bisno AL, Pharyngitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases, 5th ed. New York, NY: Churchill Livingstone; 2000:656-661.

17. Schreckenberger P. Sunrise Symposium: Practical Guidelines for Testing and Work-up of Respiratory Specimens. Presented at 103rd General Meeting of the American Society for Microbiology: May 2003; Washington, DC.

18. Klein JO, Otitis externa, otitis media, and mastoiditis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 5th ed. New York, NY: Churchill Livingstone; 2000:672-673.

19. Weinstein MP, Mirrett S, Reimer LG, et al. Controlled evaluation of BacT/ALERT standard aerobic and FAN aerobic blood culture bottles for detection of bacteremia and fungemia. J Clin Microbiol. 1995;33:978-981.

20. Altwegg M. Aeromonas and Plesiomonas. In Murray PR, Baron EJ, Pfaller MA, et al, eds. Manual of Clinical Microbiology. 7th ed. Washington, DC: American Society for Microbiology; 1999:424-433.

21. Wong CS, Jelacic S, Habeeb RL, Watkins SL, Tarr PI, The risk of the hemolytic-uremic syndrome after antibiotic treatment of Escherichia coli 0157:H7 infections. N Engl J Med. 2000;342:1930-1936.

22. Weissfeld AC, ed. Cumitech 2B--Laboratory Diagnosis of Urinary Tract Infections. Washington, DC: ASM Press; 1998.

23. Brown AE. Other Corynebacteria and Rhodococcus. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 5th ed. New York, NY: Churchill Livingstone; 2000:2198-2214.

RELATED ARTICLE: How to confuse a physician:

** Make lab reports hard to follow.

** Report an MIC on an organism, even if it is not necessary.

** Report everything that grows.

** Do identification and MICs on all anaerobes as if it really matters.

** Give bacteria a new name every year.

** Do susceptibility testing on blood-culture contaminants.

** Report dangerous organisms without a comment.

** Suggest to a physician that an old procedure is being dropped.

RELATED ARTICLE

Busy sputum Gram-stain report:

>25 PMNs <10 SEC/LPF

Moderate Gram-negative rods

Few Gram-positive cocci

Few Gram-positive rods

Few Gram-negative coccobacilli

Few Gram-positive diplococci

More user-friendly report:

>25 PMNs <10 SEC/LPF

Moderate Gram-negative cocci (suspect Moraxella/Neisseria ssp.)

Few mixed flora

RELATED ARTICLE: Errors regularly committed by laboratories

1. Lack of knowledge of what to look for (e.g., neglecting to look for acid-fast bacteria in a specimen from an infected breast prosthesis).

2. Too rigid an adherence to routine without taking note of individual circumstances.

3. Reporting everything that grows, and leaving it up to the clinician to decide on the significance.

4. Ignoring all isolates except those commonly considered important to disease.

By Colleen K. Gannon, MT(AMT), HEW

For 20 years, Colleen K. Gannon, MT(AMT), HEW, has been the section head of the microbiology department of MidMichigan Medical Center, which services the 308-bed nonprofit hospital, in addition to two other area hospitals, several nursing homes, satellite laboratories, and clinics.