The Usefulness of Chromogenic Media for Qualitative and Semi-Quantitative Diagnostic of Urinary Tract Infections

Novel Techniques to Unravel Causative Bacterial Ecological Shifts in Chronic Urinary Tract Infection

Chronic urinary tract infection (UTI) presents with protracted lower urinary tract symptoms and elevated urinary leukocyte counts, but its bacterial etiological agents remain obscure. In this cross-sectional investigation, we aimed to unravel the role of the bladder microbiota in chronic UTI pathogenesis by studying the host immune response. Urine samples were collected from healthy controls (HT), chronic UTI patients who had not initiated treatment (PT) and those undergoing treatment (OT), then sorted into white blood cell (WBC) and epithelial cell (EPC) fractions. Bacteria associated with both fractions were identified by chromogenic agar culture coupled with mass spectrometry and 16S rRNA sequencing. Distinct WBC-exclusive bacteria were observed in the healthy population, but this pattern was less obvious in patients, plausibly due to epithelial shedding and breaching of the urothelial barrier. We also described a bacterial fingerprint guided by Escherichia that was able to stratify patients based on symptom severity. Clustering analyses of mean rank changes revealed highly statistically significant upward and downward ecological shifts in communities of bacteria between the healthy and diseased populations. Interestingly, many of the most abundant genera identified in sequencing remained stable when compared between the study cohorts. We concluded that reshuffling of the urinary microbiome, rather than the activity of a single known urinary pathogen, could drive chronic UTI.

Reshaping Resistance: How Autovaccine Therapy Alters the Course of Recurrent Multidrug-Resistant Urinary Tract Infections

BACKGROUND/OBJECTIVES

Urinary tract infections (UTIs) caused by multidrug-resistant (MDR) bacteria pose a considerable challenge due to high treatment failure rates and associated healthcare costs. This pioneering study evaluates the effectiveness of personalized autovaccine therapy in managing recurrent UTIs in patients with MDR bacteria, aiming to offer an innovative treatment that reduces antibiotic resistance and hospitalizations.

METHODS

In this prospective, single-center study, 40 patients with recurrent MDR UTIs received personalized sublingual autovaccines derived from their own bacterial isolates. The study assessed UTI recurrence rates, changes in antibiotic use, and hospitalization days over 12 months.

RESULTS

The autovaccine therapy significantly reduced UTI recurrence, with 67.5% of patients experiencing fewer infections. Antibiotic usage decreased by 74.4%, and total hospitalization days annually reduced from 400 to 216. A significant shift was observed from MDR to multi-susceptible bacterial profiles among participants.

CONCLUSIONS

This study is the first to demonstrate that autovaccine therapy is a safe and effective approach for managing recurrent UTIs caused by MDR bacteria, significantly lowering infection frequency, antibiotic needs, and hospitalization. These findings support integrating autovaccine therapy into standard UTI management to combat antibiotic resistance and lessen healthcare burdens.

Improving the diagnosis of urinary tract infections by the use of enriched media and a 48-hour incubation period

Introduction. The absence of a gold-standard methodology for the microbiological diagnosis of urinary tract infections (UTI) has led to insufficient standardization of criteria for the interpretation of results and processing methods, particularly incubation time and culture media.Hypothesis. 48-hour incubation time period and use of blood agar enhances the sensitivity of microorganisms isolated significantly.Aim. To determine the sensitivity of blood agar and Brilliance UTI chromogenic agar, incubating for different periods (24-48 hours), for the detection of positive urine cultures.Methodoloy. Comparisons were made between all possible combinations of media and incubation times. As the gold-standard reference, we used the routine methodology of our laboratory, which involves prior screening with available clinical data, flow cytometry, sediment analysis and/or Gram staining. Screened samples were then cultured on blood agar and chromogenic agar and incubated for 48 hours. Also, based on the results of Gram staining, additional media were added in selected cases.Results. The most significant difference was found between chromogenic agar incubated for 24 hours and blood agar incubated for 48 hours, with the latter method allowing the recovery of 10.14 % more microorganisms (P < 0.0001). Furthermore, the value of performing Gram staining to guide processing was demonstrated, as it avoided the loss of at least 5.14 % of isolates.Conclusions. At least in urological and nephrological patients it is essential to include enriched culture media (blood agar) or to extend the incubation times due to the improvement of the diagnostic sensitivity of urine cultures. Gram staining also can help detect the presence of fastidious microorganisms or mixed infections, indicating whether rich and/or selective media should be included to enhance the diagnostic sensitivity of cultures. If this methodology is not followed, it should be noted that besides fastidious species, fastidious strains of Escherichia coli, Proteus mirabilis, Pseudomonas aerugniosa and Stenotrophomonas maltophilia will also be missed.

Predictors of urinary tract infection after lower gastrointestinal surgery

BACKGROUND

Urinary tract infections (UTIs) cause postoperative morbidity in patients undergoing lower gastrointestinal (GI) surgery that can prolong postoperative hospital stays. In patients with a fever of unknown origin (FUO), clinicians ignore what to do while waiting for the results of the urine culture test. This study aimed to develop a nomogram predicting UTI in the case of postoperative FUO.

METHODS

This observational, retrospective study included all consecutive patients from 1 November 2020 to 1 November 2021 undergoing lower-GI surgery at the Chirurgia Generale 3, University Hospital of Padua, Italy. A nomogram was created and externally validated in 90 consecutive patients undergoing urine culture tests for FUO at the Chirurgia Oncologica Unit, Veneto Institute of Oncology.

RESULTS

In the development cohort, 109 (N = 109) patients performed a urine culture test for FUO, and 39 were diagnosed with UTI. In a multivariate analysis of patients who underwent urine culture tests for FUO, UTI was associated with female sex, older age, and duration of catheterization at the date of the urine culture test. We developed a nomogram to predict UTI in surgical patients with a C-index of 0.76. In the validation cohort, 90 consecutive patients, who had lower-GI surgery, underwent a urine culture test for FUO and were tested with this nomogram. In the validation cohort, the C-index of the nomogram for predicting a positive urine culture test was 0.71.

CONCLUSIONS AND RELEVANCE

UTIs are a common problem in patients undergoing lower-GI surgery. A nomogram including the major risk factors may help to reduce the inappropriate use of antibiotics during the period awaiting the result of the urine culture test.

Chromogenic culture media complements diagnostic cytology in the visual identification of pathogenic skin bacteria in dogs and cats

In dogs and cats, bacterial skin infections (pyoderma and otitis externa) are a common cause for visiting the veterinary clinic. The most frequent skin pathogens are Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, often requiring different therapeutic antibiotic protocols. Unfavorably, existing diagnostics based on cytology cannot reveal bacterial species but only bacterial shapes such as cocci or rods. This microscopic limitation could be overcome by clinical translation of affordable chromogenic media, which enable species identification based on bacterial colonies growing in different colors and sizes. In this study, we determined how well inexperienced general veterinary clinicians identified bacterial pathogens from the skin and ears on two commercial (Chromatic™ MH and Flexicult® Vet) and one custom-made Mueller Hinton agar-based chromogenic medium. For this purpose, four veterinarians evaluated 100 unique samples representing 10 bacterial species. On average, clinicians correctly identified between 72.1 and 86.3% of bacterial species. Colony colors developed quickly on the Chromatic™ MH medium, leading to the highest 81.6% identification accuracy after 24 h incubation. However, Flexicult® Vet exhibited the highest accuracy of 86.3% after prolonged 48 h incubation. Evaluators easily recognized bacteria displaying uniquely colored colonies like green-brown Pseudomonas aeruginosa, blue Enterococcus faecalis, orange-brown Proteus spp., and red Escherichia coli. Oppositely, staphylococci shared uncharacteristically pale pink colonies causing misidentifications among the genus, deteriorating overall accuracy by around 10 percentage points (from 90.9%). Another reason for identification errors was the evaluators' inexperience, reflected in not recognizing colony size differences. For example, although Streptococcus canis exhibited the tiniest colonies, the species was frequently mistaken for other cocci. Finally, around 10% of errors were negligence-related slips due to unconsidered sample history. To conclude, the introduction of chromogenic media into veterinary clinics can significantly complement diagnostics in skin inflammations by identifying pathogen species in around 80% of cases. The extra information may help in therapeutic dilemmas on antibiotics and standard antimicrobial susceptibility testing. Additional personnel training and evaluation help by visuals, flowcharts, checklists, and, if necessary, microbiologists could further improve identification accuracy.

Evaluation of chromogenic agar medium, can it be a suitable alternative to conventional culture system for identification of uropathogens?

Background and Objectives

Urinary tract infections (UTI) account for major proportion of outpatient load and hospital admission globally. In most of the clinical microbiology laboratories MacConkey agar (MAC) and Cystine lactose electrolyte-deficient (CLED) agar are being used for identification of uropathogens. The main objective of the present study was to evaluate the usefulness of HiCrome^TM UTI by comparing isolation rate and presumptive identification of uropathogens against CLED and MAC agar.

Materials and Methods

This study was conducted over a period of three months on 672 non-duplicate midstream and/or catheter-catch urine samples. All samples were inoculated on to HiCrome^TM UTI, CLED agar and MacConkey agar.

Results

Among the 672 samples received for culture, 113 (16.8%) showed significant growth. Among the 672 samples, 95 (14.1%) showed growth of a single organism while 18 (2.7%) showed polymicrobial growth. The rate of isolation and presumptive identification of the isolates and polymicrobial growth was found significantly higher on HiCrome^TM UTI Agar.

Conclusion

HiCrome^TM UTI Agar has the potential to streamline processing of samples for urine culture in a way that will reduce the workload for technicians, reduce turnaround time which in turn will benefit the laboratory ultimately leading to better patient care.