About Guidance® UTI Testing Methodology

view sample Guidance® UTI Report

Methodology and Clinical Significance:

Guidance® UTI utilizes Multiplex PCR Polymerase Chain Reaction (PCR), a specific type of nucleic amplification technology, for the targeted molecular detection of bacterial and yeast DNA along with bacterial resistance genes.

If detected, targets are reported semi-quantitatively as cells per milliliter in the following ranges:

– <10,000 cells/mL
– 10,000-49,999 cells/mL
– 50,000-99,999 cells/mL
– >100,000 cells/mL

Identifies 27 individual organisms and 3 bacterial groups.

BACTERIAL/YEAST ORGANISMS:
  • Acinetobacter baumannii
  • Actinotignum schaalii
  • Aerococcus urinae
  • Alloscardovia omnicolens
  • Candida albicans
  • Candida auris
  • Candida glabrata
  • Candida parapsilosis
  • Citrobacter freundii
  • Citrobacter koseri
  • Corynebacterium riegelii
  • Enterococcus faecalis
  • Enterococcus faecium
  • Escherichia coli
  • Gardnerella vaginalis
  • Klebsiella oxytoca
  • Klebsiella pneumoniae
  • Morganella morganii
  • Mycoplasma hominis
  • Pantoea agglomerans
  • Proteus mirabilis
  • Providencia stuartii
  • Pseudomonas aeruginosa
  • Serratia marcescens
  • Staphylococcus aureus
  • Streptococcus agalactiae
  • Ureaplasma urealyticum
BACTERIAL GROUPS:
  • Coagulase-negative staphylococci*
  • Viridans group streptococci†
  • Enterobacter group‡
  • ESBL PHENOTYPE ASSAY
    ESBL phenotypic assay will be performed when E. coli, Klebsiella, Enterocobacter, Citrobacter, Proteus, Acinetobacter, or Pseudomonas are detected and is a chromatographic assay that detects the presence of active B-lactamase enzyme, a protein produced by bacteria that is responsible for degrading beta-lactam antibiotic, thereby renders them ineffective.
  • MRSA PHENOTYPE ASSAY
    MRSA phenotypic assay will be performed when selected and  Staphylococcus aureus and the mecA gene are detected.

*Coagulase-negative staphylococci: Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus lugdunenesis, Staphylococcus saprophyticus
†Viridans group streptococci: Streptococcus anginosus, Streptococcus oralis, Streptococcus pasteuranus
‡Enterobacter group: Klebsiella aerogenes (formally known as Enterobacter aerogenes), Enterobacter cloacae

Resistance Genes:

Guidance® UTI tests for 32 resistance genes from six different classes of antibiotics.  When detected, resistance genes detected (RGD) will be indicated on the table of the report.

Ampicillin resistance genes: AmpC, FOX, ACC, DHA, MOX/CMY, BIL/LAT/CMY
Extended-spectrum beta-lactamases (ESBL) resistance genes: CTX-M group 1, CTX-M group 2, CTX-M group 8/25, CTX-M group 9, OXA-1, SHV, TEM, VEB, GES, PER-1, PER-2
Methicillin resistance genes: mecA
Quinolone and fluoroquinolone resistance genes: QnrA, QnrS
Vancomycin resistance genes: vanA1, vnA2, vanB
Carbapenems resistance genes: IMP-1 group, KPC, OXA-23, OXA-40, blaOXA-48, VIM, IMP-7, IMP-16 OXA-72

Pooled Antibiotic Sensitivity Testing:

Pooled Antibiotic Sensitivity Testing (P-AST™) of the microbial community detects viable bacteria when applied to a panel of antibiotic agents to determine Pooled Minimum Inhibitory Concentration (Pooled MIC).

P-AST™ is not performed for Virdians streptococci, or fastidious microorganisms such as Ureaplasma urealyticum, Actinobaculum schaalii, Aerococcus urinae, Alloscardovia omnicolens, Corynebacterium riegelii, Mycoplasma hominis and Enterococcus faecium.

In addition to providing both the presence of resistance genes (RGD) and pooled antibiotic susceptibility patterns (S for sensitive, R for resistance), we also include a table of antibiotics that have shown strong supportive evidence for use in the treatment of UTI.

The checkmarks indicate situations for which

  • The FDA shows the antibiotic is efficacious for the indicated organisms
  • In vitro data shows MIC levels equal to or less than the susceptibility breakpoints
  • CLSI breakpoints are reported for urine culture
  • Or there is sufficient literature supporting the use of the efficacious use antibiotic for the organism listed.

Appropriate medical judgement should be exercised by the health care provider before prescribing a course of treatment. Further treatment or workup may be necessary if clinically indicated.

White boxes with checkmarks indicate situations where the pool of organisms was susceptible to an antibiotic and there is supportive evidence for the organisms listed. There may be changes in research showing changes in antibiotic susceptibility. Although we attempt to update the report with new data promptly, we cannot prevent delays.

Candida auris:

Candida auris is an emerging fungus that presents a serious global health threat and can be the cause of bloodstream infections, wound infections, and ear infections. It also has been isolated from respiratory and urine specimens. Click here for guidance on C. auris.

Antifungals:

We do not perform antifungal susceptibility testing.

Disclaimer:

This test was developed, and its performance characteristics determined by Pathnostics. It has not been cleared or approved by the US Food and Drug Administration. The FDA has determined that such clearance or approvals is not necessary. This test is used for clinical purposes. It should not be regarded as investigational or for research. This laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88) as qualified to perform high complexity clinical testing. Urine specimens received greater than 5 days post collection may give unreliable cells/mL counts due to overgrowth of microorganism(s).

References
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2. Kotton CN, Kumar D, Caliendo AM, et al. Updated international consensus guidelines on the management of cytomegalovirus in solid-organ transplantation. Transplantation 2013; 96:333.
3. Razonable RR, Hayden RT. Clinical utility of viral load in management of cytomegalovirus infection after solid organ transplantation. Clin Microbiol Rev 2013; 26:703.
4. Ljungman P, Griffiths P. Definitions of cytomegalovirus infection and disease. In: Plotkins S, Michelson S (eds). Multidisciplinary Approach to Understanding Cytomegalovirus Disease. Amsterdam: Excerpta Medica Congress Series. Elsevier Science Publishers: Paris, 1993, pp 233–237.
5. 20 Ljungman P, Plotkins SA. Workship on CMV disease; definitions, clinical severity scores, and new syndromes. Scand J Infect Dis Suppl 1995; 99: 87–89.

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