Predicting the resistance of beta-lactamase producing isolates to
Nitrocefin
Beta Lactamase (Penicillinase)
Lactamase, Beta (Penicillinase)
Penicillinase Activity
Varies
For shipping information see Infectious Specimen Shipping Guidelines.
Specimen source and organism identification are required.
Question ID | Description | Answers |
---|---|---|
Q00M0008 | Specimen Source (Required) and Organism Identification (Required unless concurrent identification test is ordered) |
Specimen Type: Pure culture of actively growing Enterococcus species, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, or Staphylococcus species
Container/Tube: Slant
Specimen Volume: Entire specimen
Collection Instructions: Send specimen in an approved mailing container and label as an etiologic agent/infectious substance.
See Specimen Required
Agar plate | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Varies | Ambient (preferred) | ||
Refrigerated |
Predicting the resistance of beta-lactamase producing isolates to
Various bacteria produce a class of enzymes called beta-lactamases, which may be mediated by genes on plasmids or chromosomes. Production of beta-lactamase may be constitutive or induced by exposure to antimicrobials. Beta-lactamases hydrolyze (and thereby inactivate) the beta-lactam rings of a variety of susceptible penicillins and cephalosporins. Beta-lactamases are classified by their preferred antimicrobial substrate and the effect of various inhibitors (such as clavulanic acid) on them.
Some antimicrobials, such as cefazolin and cloxacillin are resistant to such hydrolysis (at least for staphylococcal beta-lactamases).
Beta-lactamase producing strains of the following are resistant to many types of penicillin: Staphylococcus species, Hemophilus influenzae, Neisseria gonorrhoeae, Bacteroides species, Enterococcus species, and Moraxella catarrhalis.
The above organisms, when isolated from critical specimens such as blood or spinal fluid, should always be tested for beta-lactamase production.
Addition of a beta-lactamase inhibitor to a beta-lactam (such as sulbactam plus ampicillin) restores the activity of the antimicrobials.
Negative (reported as positive or negative)
A positive test indicates production of beta-lactamase.
Some beta-lactamase tests (iodometric and acidometric methods) may not detect certain beta-lactamases.
Many bacteria that do not produce beta-lactamase will be resistant to beta-lactams by other mechanisms.
This test should not be used to detect extended-spectrum beta-lactamases.
1. Livermore DM, Williams JD: Beta-lactams: mode of action and mechanisms of bacterial resistance. In: Lorian V, ed. Antibiotics in Laboratory Medicine. 4th ed. Williams and Wilkins; 1996:502-578
2. Gonzalez MD, Ledeboer NA: Haemophilus. In: Carroll KC, Pfaller MA, eds. Manual of Clinical Microbiology. 12th ed. ASM Press; 2019:682-683
A loopful of test organism is placed on a Cefinase disk, which contains the chromogenic cephalosporin, nitrocefin. Beta-lactamase will produce a change from yellow to red within 1 hour and usually within 5 minutes.( Procop, GW, Church DL, Hall GS, et al: Antimicrobial susceptibility testing. In: Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 7th ed. Lippincott, Williams and Wilkins; 2017:chap 17)
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This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
87185
Test Id | Test Order Name | Order LOINC Value |
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BLACT | Beta Lactamase | 6985-6 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
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BLACT | Beta Lactamase | 6985-6 |