Testing for Infections

What is a culture and sensitivity (C&S) test?

Explains how the laboratory grows microorganisms from a sample and then tests which antibiotics will stop them, and how to read the susceptible and resistant results.

Start here if your report mentions a culture, sensitivities, or terms like susceptible, resistant, or intermediate.

PCR, antigen, and antibody tests: what is the difference?

Explains the three main ways infections are detected and why one test can be positive while another is negative for the same infection.

Start here if you have results from more than one type of test, or you are not sure whether a positive result means a current or a past infection.

IgM and IgG Antibodies: Understanding Your Test Results

Explains what antibody (serology) results mean, and how IgM and IgG help show whether an infection is recent, in the past, or one you are now protected against.

Start here if your report lists IgM, IgG, “reactive,” “non-reactive,” or an antibody titer.

Gram Stain: Understanding Your Report

Explains how this quick test sorts bacteria by color and shape to give an early clue about the type of infection before the full culture is ready.

Start here if your report mentions a Gram stain, gram-positive or gram-negative bacteria, or cocci and rods.

Blood Culture: Understanding Your Report

Walks through the common results on a blood culture report, from “no growth” to a named organism, and what each step means for your care.

Start here if your report says “no growth,” “preliminary,” or names bacteria or yeast found in your blood.

COVID-19 testing

Explains the PCR, rapid antigen, and antibody tests for the virus that causes COVID-19, and what a positive or negative result means for each.

You may find this helpful if you have a PCR or rapid antigen result, an antibody (serology) result, or if you are unsure which test you had.

HIV testing

Explains how HIV screening, confirmatory testing, viral load, and CD4 count fit together, and what each result tells you.

You may find this helpful if your report mentions an HIV screen, a confirmatory test, a viral load, or a CD4 count.

Hepatitis B testing

Explains the hepatitis B blood markers and what different combinations mean — a current infection, a past infection, or immunity from vaccination.

You may find this helpful if your report lists HBsAg, anti-HBs, or anti-HBc, or if you were told you are immune, a carrier, or need the vaccine.

Hepatitis C testing

Explains the difference between a hepatitis C antibody test and an RNA (viral load) test, and why both may be needed to confirm a current infection.

You may find this helpful if your report shows a hepatitis C antibody result, an HCV RNA or viral load result, or a “reactive” screen.

Mononucleosis (EBV) testing

Explains the “mono spot” test and the Epstein-Barr virus antibodies used to diagnose infectious mononucleosis.

You may find this helpful if your report mentions a monospot, heterophile antibodies, EBV, or VCA IgM and IgG.

Cytomegalovirus (CMV) testing

Explains the antibody and viral load tests for CMV, a common virus that matters most during pregnancy and after a transplant.

You may find this helpful if your report mentions CMV IgM or IgG, a CMV viral load (PCR), or testing was ordered during pregnancy.

Urine culture

Explains how a urine culture confirms a urinary tract infection, identifies the bacteria responsible, and reports the colony count.

You may find this helpful if your report mentions a urine culture, colony-forming units (CFU), “mixed flora,” or a named bacterium.

Throat culture and strep testing

Explains the rapid strep test and the throat culture used to check for strep throat, and what positive and negative results mean.

You may find this helpful if you had a rapid strep test, a throat swab culture, or your report mentions group A streptococcus.

Stool culture

Explains how a stool sample is cultured to find the bacteria that cause diarrhea and other digestive infections.

You may find this helpful if your report mentions a stool culture, Salmonella, Shigella, Campylobacter, or E. coli.

Wound and sputum cultures

Explains how samples taken from a wound or coughed up from the lungs are cultured to identify the cause of an infection.

You may find this helpful if your report mentions a wound culture, a sputum culture, or bacteria growing from a swab or sample.

Clostridioides difficile (C. diff) testing

Explains the stool tests used to diagnose a C. difficile infection, a common cause of diarrhea after taking antibiotics.

You may find this helpful if your report mentions C. diff, a C. difficile toxin test, or a stool PCR after a course of antibiotics.

Helicobacter pylori (H. pylori) testing

Explains the breath, stool, blood, and biopsy tests for H. pylori, the bacteria linked to stomach ulcers and gastritis.

You may find this helpful if your report mentions H. pylori, a urea breath test, a stool antigen test, or it was found on a stomach biopsy.

Syphilis testing

Explains how screening tests such as RPR and confirmatory treponemal tests are read together to diagnose syphilis.

You may find this helpful if your report mentions RPR, VDRL, a treponemal antibody test, or a “reactive” syphilis screen.

Gonorrhea and chlamydia testing

Explains the molecular (NAAT) tests used to detect two of the most common sexually transmitted infections.

You may find this helpful if your report mentions a NAAT, gonorrhea (GC), chlamydia, or a combined urine or swab test.

Tuberculosis (TB) testing

Explains the skin test, the blood test (IGRA), and the AFB smear and culture used to check for tuberculosis.

You may find this helpful if your report mentions a TB skin test (PPD), QuantiFERON or IGRA, AFB, or a positive TB screen.

Fungal testing

Explains the cultures, special stains, and blood tests used to find fungal (yeast and mold) infections.

You may find this helpful if your report mentions a fungal culture, yeast, Candida, Aspergillus, or a KOH preparation.

Ova and parasite (stool) testing

Explains how a stool sample is examined under the microscope to look for parasites and their eggs.

You may find this helpful if your report mentions an O&P test, a stool exam for parasites, Giardia, or worms or eggs.

Blood tests

Plain-language guides to common blood tests, including the CBC, metabolic panels, and the liver panel.

You may find this helpful if your report includes a CBC, electrolytes, or liver enzymes alongside your infection tests.

Pathology Dictionary

Short, plain-language definitions of single terms you may see in your report.

You may find this helpful if you only need a quick definition of one word or abbreviation.