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Introduction to Antibiotic Spotlights

Welcome to our UTI Knowledge Center! Here you will find links to individual posts for each antibiotic tested in the Guidance® UTI assay. These spotlights aim to answer common questions about each antibiotic. Each spotlight post has several sections describing key features of the antibiotic. Continue reading below to learn about each section.

Administration Routes

This section lists the available administration route(s) for the listed antibiotic.  This information comes from the FDA-approved product labels and package inserts.[1] Some antibiotics for UTI can be taken orally (PO).[2] Others need parenteral administration. Parenteral administration routes include[2]:

  • Intravenous infusion (IV)
  • Intramuscular injection (IM)

PO is the least invasive administration route and is usually the preferred option in outpatient care. The IM route may be utilized in clinical offices. IV is the most invasive option, usually given at a specialized facility.

Bacteriostatic or Bactericidal

“Bactericidal” antibiotics directly kill bacteria. “Bacteriostatic” antibiotics prevent bacterial growth and replication. Both types of antibiotics are effective in clinical practice.[3]

Antibiotic Class

This section lists the class of the antibiotic. Antibiotic classes describe groups of antibiotics with related:[4]

  • Molecular structures
  • Mechanism(s) of action

Mechanisms of Action

This section provides a brief description of how the antibiotic works. The “mechanism of action” blocks one of four bacterial processes: [5]

  • Bacterial Cell Wall Building
  • Bacteria DNA Replication and Repair
  • Bacterial Ribosomes and Protein Synthesis
  • Bacterial Folate Metabolism

WHO AWaRe Classification

The World Health Organization (WHO) has developed the AWaRe classification system.[4] The goal is to support global antibiotic stewardship efforts.   AWaRe stands for “Access”, “Watch”, and “Reserve”. These three classes describe the appropriate stewardship for the antibiotic:

  1. Access: These antibiotics are lower-risk for antibiotic resistance. They should be considered for first-line and empiric uses.
  2. Watch: These antibiotics are higher-risk for antibiotic resistance. They should be used for infections with confirmed susceptibility.
  3. Reserve: These antibiotics are for infections with multi-drug-resistant organisms. They are considered ‘last resort’ options.

Empiric Use Recommendations

Antibiotics recommended for empiric therapy are marked “yes”. Recommendations come from guidelines by the following organizations:

  • World Health Organization (WHO)[4]
  • Infectious Diseases Society of America (IDSA) & European Society for Microbiology and Infectious Disease[6]
  • American Urological Association (AUA)[7]

Indication(s) Relevant to UTI

This section lists any UTI-related indications for use. Indications are according to FDA-approved product labels and package inserts.[1]

Checkmarks

This section lists which organisms from the Guidance® UTI test can be treated by the antibiotic.  These recommendations appear as checkmarks on Guidance® UTI result reports.

Sources are 1) the Clinical and Laboratory Standards Institute (CLSI),[8] 2) the United States Food and Drug Administration (FDA)[9]:

  • M100: Performance Standards for Antimicrobial Susceptibility Testing, 35th Edition (2025)
  • M43-A: Methods for Antimicrobial Susceptibility Testing for Human Mycoplasmas, 1st Edition (corrected 2015)
  • M45: Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria, 3rd Edition (corrected 2017)

The CLSI and FDA guidance documents do not provide guidance for treatment of A. schaalii, A. omnicolens, or G. vaginalis. Instead, primary peer-reviewed literature references are provided where applicable. [10–18]

References

  1. Drugs@FDA: FDA-Approved Drugs Available online: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=browseByLetter.page&productLetter=P&ai=0 (accessed on 6 February 2025).
  2. Medication Routes of Administration – StatPearls – NCBI Bookshelf Available online: https://www.ncbi.nlm.nih.gov/books/NBK568677/ (accessed on 9 April 2025).
  3. Ishak, A.; Mazonakis, N.; Spernovasilis, N.; Akinosoglou, K.; Tsioutis, C. Bactericidal versus Bacteriostatic Antibacterials: Clinical Significance, Differences and Synergistic Potential in Clinical Practice. J. Antimicrob. Chemother. 2024, 80, 1–17, doi:10.1093/jac/dkae380.
  4. AWaRe Classification of Antibiotics for Evaluation and Monitoring of Use, 2023 Available online: https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2023.04 (accessed on 6 February 2025).
  5. Halawa, E.M.; Fadel, M.; Al-Rabia, M.W.; Behairy, A.; Nouh, N.A.; Abdo, M.; Olga, R.; Fericean, L.; Atwa, A.M.; El-Nablaway, M.; et al. Antibiotic Action and Resistance: Updated Review of Mechanisms, Spread, Influencing Factors, and Alternative Approaches for Combating Resistance. Front. Pharmacol. 2024, 14, 1305294, doi:10.3389/fphar.2023.1305294.
  6. Gupta, K.; Hooton, T.M.; Naber, K.G.; Wullt, B.; Colgan, R.; Miller, L.G.; Moran, G.J.; Nicolle, L.E.; Raz, R.; Schaeffer, A.J.; et al. International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis 2011, 52, e103–e120, doi:10.1093/cid/ciq257.
  7. Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline (2022) – American Urological Association Available online: https://www.auanet.org/guidelines-and-quality/guidelines/recurrent-uti (accessed on 6 February 2025).
  8. CLSI Standards Products Available online: https://clsi.org/standards/products/new-products/documents/ (accessed on 6 February 2025).
  9. Antibacterial Susceptibility Test Interpretive Criteria | FDA Available online: https://www.fda.gov/drugs/development-resources/antibacterial-susceptibility-test-interpretive-criteria (accessed on 6 February 2025).
  10. Lotte, R.; Lotte, L.; Ruimy, R. Actinotignum Schaalii (Formerly Actinobaculum Schaalii): A Newly Recognized Pathogen—Review of the Literature. Clin Microbiol Infec 2016, 22, 28–36, doi:10.1016/j.cmi.2015.10.038.
  11. Beguelin, C.; Genne, D.; Varca, A.; Tritten, M. ‐L.; Siegrist, H.H.; Jaton, K.; Lienhard, R. Actinobaculum Schaalii: Clinical Observation of 20 Cases. Clin Microbiol Infec 2011, 17, 1027–1031, doi:10.1111/j.1469-0691.2010.03370.x.
  12. Cattoir, V.; Varca, A.; Greub, G.; Prod’hom, G.; Legrand, P.; Lienhard, R. In Vitro Susceptibility of Actinobaculum Schaalii to 12 Antimicrobial Agents and Molecular Analysis of Fluoroquinolone Resistance. J Antimicrob Chemoth 2010, 65, 2514–2517, doi:10.1093/jac/dkq383.
  13. Isnard, C.; Lienhard, R.; Reissier, S.; Rodriguez, S.; Krähenbühl, J.; Liassine, N.; Guérin, F.; Cattoir, V. In Vitro Antimicrobial Susceptibility of Alloscardovia Omnicolens and Molecular Mechanisms of Acquired Resistance. Diagnostic Microbiology and Infectious Disease 2016, 84, 227–229, doi:10.1016/j.diagmicrobio.2015.08.009.
  14. Akamine, C.M.; Chou, A.; Tavakoli-Tabasi, S.; Musher, D.M. Gardnerella Vaginalis Bacteremia in Male Patients: A Case Series and Review of the Literature. Open Forum Infect. Dis. 2022, 9, ofac176, doi:10.1093/ofid/ofac176.
  15. Sahuquillo-Arce, J.M.; Suárez-Urquiza, P.; Hernández-Cabezas, A.; Tofan, L.; Chouman-Arcas, R.; García-Hita, M.; Sabalza-Baztán, O.; Sellés-Sánchez, A.; Lozano-Rodríguez, N.; Martí-Cuñat, J.; et al. Actinotignum Schaalii Infection: Challenges in Diagnosis and Treatment. Heliyon 2024, 10, e28589, doi:10.1016/j.heliyon.2024.e28589.
  16. Pedraza-Avilés, A.G.; Zaragoza, M.C.; Mota-Vázquez, R.; Hernández-Soto, C.; Ramírez-Santana, M.; Terrazas-Maldonado, M.L. Treatment of Urinary Tract Infection by Gardnerella Vaginalis: A Comparison of Oral Metronidazole versus Ampicillin. Revista Latinoamericana De Microbiol 2001, 43, 65–69.
  17. Li, T.; Zhang, Z.; Wang, F.; He, Y.; Zong, X.; Bai, H.; Liu, Z. Antimicrobial Susceptibility Testing of Metronidazole and Clindamycin against Gardnerella Vaginalis in Planktonic and Biofilm Formation. 2020, 1361825.
  18. Ruiz-Gómez, M.L.; Martín-Way, D.A.; Pérez-Ramírez, M.D.; Gutiérrez-Fernández, J. [Male deep infections by Gardnerella vaginalis. A literature review and a case      report]. Rev Esp Quimioter 2019, 32, 469–472.

About the Author

Dr. Emery Haley is a scientific writing specialist with over ten years of experience in translational cell and molecular biology. As both a former laboratory scientist and an experienced science communicator, Dr. Haley is passionate about making complex research clear, approachable, and relevant. Their work has been published in over 10 papers and focuses on bridging the gap between the lab and real-world patient care to help drive better health outcomes.

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