Study design, materials and methods
Data was collected retrospectively, from the previous two years by the department of microbiology at FJMU, starting from January 2021 to December 5, 2022. Data was collected over a span of two years. Samples were collected from inpatient as well as outpatient departments of the hospital. Total samples collected during these two years were 4462. Midstream clean-catch urine samples were collected in sterile containers.
The properly collected sterile samples were cultured on CLED agar (Cystine Lactose Electrolyte Deficient) media with a standard calibrated loop and incubated at 37 oC overnight. The culture and sensitivity reports of urine with positive Pseudomonas aeruginosa showing 10 *5 colony forming units/ml were considered significant bacteuria.
The organism grows well at 25°C to 37°C. Its ability to grow at 42°C helps to distinguish it from many other pseudomonas species. Thereafter, an antibiotic sensitivity test was done by the Kirby-Bauer disc diffusion method on mueller hinton agar, and readings were taken using clinical and laboratory standard institute guidelines. Antibiotic sensitivity was tested for major antibiotic groups including Ceftriaxone (30µg), Ceftazidime (30µg), Cefuroxime (30µg), Gentamicin (10µg), Amikacin (30µg), Neomycin (10µg), Tetracycline (30µg), Ciprofloxacin (5µg), Imipenem (10µg), Aztreonam (15µg), fosfomycin (50µg), and colistin (30µg).
Results
Total samples collected during these two years were 4462. Out of these samples, the total number of samples that showed positive cultures was 493 (11%). Out of which, 40 (8.1%) samples came out positive for P. aeruginosa. In 2021, the number of samples that showed growth was 189 (8.4%), and the positivity rate increased to 304 (14%).
The number of urine samples showing the growth of P. aeruginosa also increased from 2021 to 2022. The results showed highest sensitivity to colistin (100%), followed by fosfomycin (60% in 2021), and Aztreonam (46.70% in 2021, However, these statistics dropped drastically in the year 2022 for both fosfomycin and azatreonam. Overall, the sensitivity to Ceftriaxone, Ceftazidime and Cefuroxime (8% in 2021 and 7% in 2022) remained low (Table-II). Similar results were seen with Amikacin (20% in 2021 and 12% in 2022), Gentamicin (20% in 2021 to 16% in 2022) and Neomycin (33.3% in 2021 to 28% in 2022). Between the aminoglycosides, there was more sensitivity to Gentamicin than Amikacin. Sensitivity also declined for Tetracyclines and ciprofloxacin (13.30% in 2021 to 8% in 2022)
Interpretation of results
A total of 4462 samples were collected during the above mentioned two-year period. Out of these samples, the total number of samples that showed positive cultures was 493 (11%). In 2021, the number of samples that showed growth was 189 (8.4%) and the positivity rate increased to 304 (14%).Overall, the highest sensitivity was recorded for colistin (100%) and remained low for the rest of the antibiotic groups, including cephalosporins, beta lactams, fluoroquinolones, aminoglycosides, and tetracyclines.