What are the expected urinalysis findings in a patient with Mycoplasma genitalium infection?

From the Guidelines

Urinalysis findings in a patient with Mycoplasma genitalium infection typically show pyuria (white blood cells in urine) without bacteria visible on standard culture. The urinalysis may reveal 5-10 or more white blood cells per high-power field, indicating inflammation in the urinary tract, as supported by the recent guidelines from the European Association of Urology 1. Leukocyte esterase may be positive, reflecting the presence of these white blood cells. Nitrites are usually negative since M. genitalium does not reduce nitrates like many common urinary pathogens. The urine may appear cloudy due to the inflammatory response, but pH and specific gravity typically remain normal. It's essential to note that standard urine cultures will be negative despite symptoms of urethritis, as M. genitalium cannot be detected by routine culture methods, highlighting the need for specific nucleic acid amplification tests (NAATs) on urine or urogenital swab samples for definitive diagnosis, as emphasized in the 2018 update by the Infectious Diseases Society of America and the American Society for Microbiology 1. These findings reflect M. genitalium's nature as a slow-growing, cell wall-deficient bacterium that causes non-gonococcal urethritis but evades detection by conventional diagnostic methods. Key points to consider in the diagnosis and management of M. genitalium infections include:

• The importance of NAATs for detection due to their increased sensitivity and specificity 1
• The need to consider local epidemiology and risk factors in screening for sexually transmitted infections 1
• The role of empiric treatment in severe cases of urethritis, with the option to delay treatment in mild cases until diagnostic results are available 1

From the Research

Expected Urinalysis Findings

In patients with Mycoplasma genitalium infection, the expected urinalysis findings may include:

• Pyuria (presence of white blood cells in the urine) 2, 3
• Hematuria (presence of blood in the urine) may be present in some cases, although it is not a specific finding for Mycoplasma genitalium infection
• Proteinuria (presence of protein in the urine) may be present in some cases, although it is not a specific finding for Mycoplasma genitalium infection
• Leukocyte esterase positive (indicating the presence of white blood cells in the urine) 2, 3
• Nitrite negative (Mycoplasma genitalium does not reduce nitrate to nitrite)

Urine Culture and Nucleic Acid Amplification Testing

• Urine culture is not typically used for the diagnosis of Mycoplasma genitalium infection, as the organism is difficult to culture 2, 3
• Nucleic acid amplification testing (NAAT) is the preferred method for diagnosing Mycoplasma genitalium infection, and can be performed on urine samples 2, 3, 4, 5, 6

Other Findings

• The presence of Mycoplasma genitalium DNA in urine samples can be detected using NAAT, and this is a specific finding for the infection 2, 3, 4, 5, 6
• The bacterial load in urine samples can vary, and may be affected by the presence of mutations in the 23S rRNA gene 4