A New Approach to Imaging and Rapid Microbiome Identification for Prostate Cancer Patients Undergoing Radiotherapy

Abstract

(1) Background: Little is known about the impact of urinary microflora, in particular, its effects on side effects after radiotherapy. The use of mass spectrometry identification method (MALDI) may bring a new look at the issue of the composition and significance of the urinary microbiome. This study aimed to use the mass spectrometry identification method (MALDI) to identify the microbiome of urine samples collected from 50 irradiated prostate cancer patients. (2) Methods: Blood and urine samples were collected before gold marker implantation, at the start and last day of radiotherapy, 1, 4 months after. Patients do not always collect the urine from the midstream; therefore, samples were collected from the first void and midstream in 12 patients for MALDI analysis; in the remaining 38 patients—from the midstream void for MALDI and biochemical analysis. (3) Results: Microorganisms were present in 140/181 urine samples. We found 33 different species 3G(−) and 30G(+). The most frequently isolated strains were: Staphylococcus haemolyticus, Staphylococcus epidermidis, Staphylococcus hominis, Enterococcus faecalis, and Micrococcus luteus. When comparing the type of urine samples, bacteria were more common in samples from the first-void urine than from the midstream one. The absence of bacteria was found in 12.2% of samples from the first-void urine and in 24.7% from the midstream. There was no difference in the total incidence of species between streams (p = 0.85). Before fiducial implantation, the total number of detected bacterial species was significantly higher in comparison to the end of radiotherapy (p = 0.038), indicating that the administered therapy resulted in depleting the local microbiome. One month after radiotherapy, an increase in the number of isolated bacteria was observed. The number of bacterial species in urine did not correlate with blood parameters. The presence of leukocytes (p = 0.013) and proteins (p = 0.004) in urine was related to a greater variety of bacteria found in urine specimens. (4) Conclusions: We obtained a similar spectrum of bacteria from the initial and middle urine streams. We also showed that there is a change in bacteria species affected by the treatment of prostate cancer patients, with both antibiotics before gold fiducial implantation and radiotherapy.

Urine microbiome changes during and after radiotherapy for prostate cancer

“…If accurate identification was not achieved for certain isolates, the test was repeated using the method involving the preparation of protein extracts with acetonitrile and formic acid. The specific procedure for this method is outlined in our prior publication(4).…”

“…Urine and blood samples were systematically collected from 88 prostate cancer patients who undergo radiotherapy, a total of 528 urine samples were obtained. The sample collection process was executed at six stages throughout their treatment course, denoted as follows: Stage t1 – before the placement of gold fiducial markers within the prostate gland, Stage t2 – on the first day of radiotherapy, Stage t3 – on the last day of radiotherapy, Stage t4 – one month after radiotherapy, Stage t5 – four months after radiotherapy, and Stage t6 – seven months after radiotherapy as previously reported(4). At time point t1, patients had blood and urine collected at least 1 day before starting antibiotics and before rectal debridement.…”

“…But still, radiotherapy not only treats the cancer but also irradiates nearby other anatomical structures such as the urinary tract or intestines, where some early and late side effects are often observed (2,3) . Some of our patients report urinary tract problems which depend on the dose, on the amount of healthy tissue that is exposed to the radiation, and they are patient specific (4) . Urinary toxicity may decrease patients quality of life presenting as difficult, frequent, or painful urination, urinary leakage, blood in urine, abdominal cramping, and nocturia.…”

“…This study aimed to use the MALDI technique with previously established conditions( 4 ) to identify the microbiome and assess its changes in urine samples of patients irradiated for prostate cancer. The composition of the microbiome was analyzed at various time points before gold fiducial implantation to assess the primary bacterial composition in urine (before the use of antibiotics); then at the beginning and end of radiotherapy; and during follow-up, 1, 4, 7 months after the end of irradiation.…”

Study of sample preparation influence on bacterial lipids profile in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

“…The studies used bacterial strains isolated from the urine of patients diagnosed with prostate cancer. Urine samples were collected from prostate cancer patients and immediately frozen at À80 C. In order to isolate bacteria, urine was inoculated directly onto various culture media (Tryptic Soy Agar, Schaedler Agar, CLED Agar) and incubated overnight at 37 C (Ma slak et al, 2022). Grown bacterial colonies were identified by the MALDI technique using a Bruker microflex mass spectrometer with Biotyper database (Bruker Daltonics, Bremen, Germany).…”