A susceptibility result can shift before the organism changes. That is why A.F. GENITAL SYSTEM must be considered together with inoculum, atmosphere, incubation, and endpoint reading. The discussion below connects its documented role with preparation variables, controls, interpretation, and the limits of inference. Catalogue 74156 is discussed as a laboratory measurement component; implementation should follow the laboratory SOP and validated reference method.
Analytical scope and method role
A.F. Genital System is a 24-well system containing desiccated biochemical and antibiotic substrates for detection, presumptive identification and susceptibility testing of microorganisms from urogenital specimens. The system also provides a semi-quantitative assessment of the presence of urogenital mycoplasmas, i.e. Mycoplasma hominis and Ureaplasma urealyticum. The system is inoculated with the suspension of the clinical sample and incubated at 36 ± 1°C. The test results are read after 24 hours of incubation and interpreted by assessing the change in color of the various wells and performing a microscopic examination. Note: The species Ureaplasma urealyticum has been divided into two new species: Ureaplasma parvum and Ureaplasma urealyticum. They are considered together as Ureaplasma spp.
Method principle
OF THE METHOD A.F. Genital System allows the detection, semi-quantitative count, presumptive identification and susceptibility test of Mycoplasma hominis and Ureaplasma spp., and the detection and presumptive identification of the microorganisms most frequently isolated from vaginal and urethral swabs and seminal fluid: Trichomonas vaginalis, Escherichia coli, Proteus spp./ Providencia spp., Pseudomonas spp., Gardnerella vaginalis, Staphylococcus aureus, Enterococcus faecalis, Neisseria gonorrhoeae, Streptococcus agalactiae (Group B) and Candida spp. •The semi-quantitative count of Ureaplasma spp. is indicated by a color change from yellow to red in wells 1-Uu 103, 2-Uu 104 and 3-Uu ≥ 105. •The semi-quantitative count of Mycoplasma hominis is evidenced by a color change from yellow to red in wells 4-Mh 104 and 5-Mh ≥ 105.
Preparation and execution: controlled method points
Preparation: OF THE CLINICAL SAMPLE Carefully open a vial of Physiological Solution* using the ampule cracker provided with the kit. 1. VAGINAL SWAB – URETHRAL SWAB Immerse the swab (after obtaining the clinical material) in the vial of physiological solution and wait 5 minutes. Carefully squeeze the swab against the vial wall so that the clinical material is dispersed homogeneously in the Physiological Solution. Note: Keep the swab, dipped in a nutritive broth, until the conclusion of the test. 2.
Procedure: envisaged for the microbiological culture examination. The samples must be sent for inoculation in the A.F. Genital System immediately after they are taken. Do not store in the refrigerator for even limited periods of time, since low temperatures may damage the vitality of some particularly sensitive microorganisms (e.g. Trichomonas vaginalis, Neisseria gonorrhoeae etc.) and alter the final result. / 211 © Liofilchem - A.F. Genital System - Rev.8 / 03.08.2020
Translate the method into controlled worksheet fields: catalogue and lot, preparation mass or volume, water quality, pH where applicable, heating or sterilization, supplements, dispense volume, preparation date, expiry assignment, incubation atmosphere and temperature, reading window, equipment, and analyst. Record departures as deviations instead of silently normalizing them.
Quality control: what the control result protects
Every batch of A.F. Genital System is subjected to
Challenge both sides of performance. Include a target reaction demonstrating recovery and, when relevant, a non-target or alternate reaction challenging inhibition or differentiation. Record expected and observed responses, acceptance criteria, strain and passage, lot, incubation, and disposition. A failed control blocks result interpretation until the cause is resolved.
Interpretation and confirmation pathway
OF THE RESULTS Count and Identification of mycoplasmas / ureaplasmas Watch for the color change in the wells 1-Uu 103 to 5-Mh ≥ 105 and interpret the results using Table 1. Detection of Trichomonas vaginalis and Candida spp. Take a drop of liquid from the well, deposit it on a glass slide, place a cover slip on top and examine at the microscope (40x) for the presence of T. vaginalis and Candida spp. Interpret as indicated in Table 1.
Record the raw observation before the conclusion: morphology or colour, growth pattern, endpoint, reaction intensity, reading time, and control response. Presumptive reactions remain presumptive. Route atypical, weak, mixed, or delayed reactions through the confirmation step in the current method.
Storage, stability, and pre-use inspection
OF THE SAMPLES Obtain the vaginal or urethral secretion with synthetic fibre swabs. Obtain the seminal fluid according to the
Receipt and storage records should reconstruct temperature exposure, lot rotation, expiry, container integrity, and time outside controlled storage. Inspect colour, clarity, fill volume, gel integrity, contamination, dehydration, and precipitate before use.
Limitations and boundaries of use
Neisseria gonorrhoeae, Streptococcus agalactiae and Gardnerella vaginalis require appropriate culture media, and additional biochemical and/or serological tests for complete identification. -Some bacteria that are present in quantities of ≥ 106-7 CFU/mL and produce urease, may cause all the wells in the panel to change colour. The presence of these can be verified by reisolating on agar medium (e.g. chocolate agar) from the original broth (see
Applicability depends on matrix, target organism, interfering flora, inoculum, validated method, and regulatory setting. Do not transfer conditions or acceptance criteria from a different matrix without verification.
Troubleshooting from evidence, not guesswork
- Poor recovery: check preparation, pH, overheating, supplement addition, inoculum, atmosphere, storage, and control performance.
- Loss of selectivity: review formulation, sterilization, expiry, inoculum burden, enrichment sequence, and incubation time.
- Weak or atypical reaction: confirm reading time and atmosphere, compare controls, document mixed growth, and follow confirmation requirements.
- Run-to-run drift: trend lot, analyst, equipment, water, preparation batch, controls, and environmental conditions.
External method context
The product should be understood as one measurement component in an antimicrobial susceptibility method. The analytical chain includes isolate purity, standardized inoculum, medium composition, antimicrobial concentration, incubation atmosphere and time, endpoint reading, and the interpretive table selected by the laboratory. A shift in any upstream variable can move an MIC or zone without a change in organism biology, which is why QC distributions and trend review are more informative than a single pass/fail control.
External laboratory-quality guidance also supports a lifecycle view: verify the method when introduced, bridge new lots against an accepted lot, trend control results, investigate nonconformities, and retain enough raw observations to reconstruct the decision. This is the practical difference between reproducing a preparation instruction and demonstrating that the resulting measurement is fit for its intended use.
EUCAST disk diffusion and quality control
EUCAST requires standardized methodology, current breakpoint tables, and routine quality control; the laboratory remains responsible for the final susceptibility report. For broth dilution, inoculum density, cation content, pH, incubation atmosphere, endpoint definition, and two-fold dilution design influence MIC reproducibility. Breakpoints are interpretive rules applied after a technically valid MIC or zone measurement; they are not properties of the product alone. Review the authoritative source.
FDA Bacteriological Analytical Manual
FDA BAM methods organize food microbiology around validated sampling, preparation, enrichment, isolation, and confirmation steps, with method applicability tied to the matrix and target organism. Sampling uncertainty, homogenization efficiency, inhibitory ingredients, dilution design, and countable range can dominate the result before the culture medium is ever inoculated; those variables belong in method verification and uncertainty review. Review the authoritative source.
WHO Laboratory Quality Management System handbook
WHO laboratory quality guidance treats document control, equipment, purchasing and inventory, process control, records, occurrence management, and continual improvement as connected parts of reliable testing. Review the authoritative source.
Technical references
- Manufacturer product documentation for catalogue 74156.
- EUCAST disk diffusion and quality control (access checked 2026-07-20).
- FDA Bacteriological Analytical Manual (access checked 2026-07-20).
- WHO Laboratory Quality Management System handbook (access checked 2026-07-20).
Bench-use checklist
- Verify product identity, catalogue number, lot, expiry, and storage history.
- Document preparation and incubation exactly as controlled in the SOP.
- Define controls and acceptance criteria before testing.
- Record raw observations, control response, reading time, and confirmation decision.
- Escalate failed controls, atypical reactions, and departures through the quality system.