A simple, easy-to-implement HPLC method was developed and validated for simultaneous determination of two isothiazolinone preservatives, methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), in hair care shampoo containing plant extracts. In this method, shampoo samples were first dissolved in isopropyl myristate and then MCI and MI were extracted from isopropyl myristate layer by a mixture of methanol and 0.02 M phosphate buffer solution pH 3.0 (30: 70, v/v) and analyzed on an analytical biphenyl column maintained at 25°C with a mixture of methanol and water (10: 90, v/v) in isocratic elution mode as mobile phase. Total flow rate of mobile phase was maintained at 1.0 mL per minute. The UV detection was performed at 274 nm. Injection volume was 50 μl. The method was fully validated in terms of specificity, linearity, precision, accuracy, and robustness according to requirements of AOAC International and was proved as reliable and suitable for the intended application.

Objective: To determine antibiotic susceptibility patterns of Pseudomonas aeruginosa isolated at the 108 Military Central Hospital from January 2020 to June 2022. Subject and method: A total of 784 Pseudomonas aeruginosa strains were isolated from patient specimens from different departments. Bacteria identification and antibiotic susceptibility test were performed using the Vitek MS system and the Vitek-2 Compact system, respectively. Multidrug-resistant and/or carbapenem-resistant Pseudomonas aeruginosa (MDR/CPR P. aeruginosa) strains were determined. Colistin susceptibility test was done using cation-modified Muller-Hinton broth diffusion method (CBDE, colistin broth disk elution). Result: Pseudomonas aeruginosa was highly resisting to fluoroquinolones (62.8%), and aminoglycosides (53.4%). The proportion of MDR/CPR P. aeruginosa was 54.3% (426/784), of which the highest proportion was found in the Department of Infectious Diseases (65.52%), ICU (64.39%) and the Internal Respiratory Department (45.69%). Carbapenem-resistant Pseudomonas aeruginosa was highly prevalent in urine specimens (65.38%) and respiratory specimens (56.76%). Of 258 MDR/CPR P. aeruginosa isolates, 11.2% isolates were resistant to colistin, 26.6% and 33.3% of these remained susceptible to amikacin and piperacillin/tazobactam, respectively. Conclusion: The prevalence of antibiotic resistante Pseudomonas aeruginosa remains high, including resistance to carbapenem and colistin. Antibiotic regimen should include amikacin or piperacillin/tazobactam in combination with other antibiotics. The study suggested the routine application of diagnostic tools for the rapid detection of resistant strains.