Susceptibility Testing of Pseudomonas Aeruginosa by the Vitek 2 System: A Comparison with Etest Results (original) (raw)
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Antimicrobial use and Pseudomonas aeruginosa susceptibility profile in a cystic fibrosis centre
The susceptibility patterns of 1315 mucoid and non-mucoid Pseudomonas aeruginosa strains from 224 patients were determined along with antibiotic utilisation in a Cystic Fibrosis Centre from 1993 to1997. Ceftazidime was the most active agent (86.0% sensitive isolates), followed by piperacillin-tazobactam (81.7%), aztreonam (80.3%), imipenem (80%), piperacillin (76.8%), tobramycin (76.5%), ciprofloxacin (73.7%), ticarcillin (72.4%), ticarcillin-clavulanic acid (70.2%), amikacin (69.5%), netilmicin (56.5%), meropenem (79%) and imipenem (75.5%). The most frequently used compounds were nebulized colistin (mean ± S.D., 109 ± 45 defined daily doses per 1000 patients per day), followed by ciprofloxacin (98 ± 8), tobramycin (55 ± 9), ceftazidime (31 ± 8) and amikacin (55 ± 9). The mean antibiotic consumption by our CF patients was 413 ± 47 defined daily doses per 1000 patients per day. Trend testing showed a significant decline of susceptibility to aminoglycosides, imipenem and ciprofloxacin, while the susceptibility of P. aeruginosa to piperacillin and ceftazidime was stable.
Archives of Pediatrics & Adolescent Medicine, 2011
Objective: To investigate the efficacy and safety of 4 antipseudomonal treatments in children with cystic fibrosis with recently acquired Pseudomonas aeruginosa infection. Design: Randomized controlled trial. Setting: Multicenter trial in the United States. Participants: Three hundred four children with cystic fibrosis aged 1 to 12 years within 6 months of P aeruginosa detection. Interventions: Participants were randomized to 1 of 4 antibiotic regimens for 18 months (six 12-week quarters) between December 2004 and June 2009. Participants randomized to cycled therapy received tobramycin inhalation solution (300 mg twice a day) for 28 days, with oral ciprofloxacin (15-20 mg/kg twice a day) or oral placebo for 14 days every quarter, while participants randomized to culture-based therapy received the same treatments only during quarters with positive P aeruginosa cultures. Main Outcome Measures: The primary end points were time to pulmonary exacerbation requiring intravenous antibiotics and proportion of P aeruginosa-positive cultures. Results: The intention-to-treat analysis included 304 participants. There was no interaction between treatments. There were no statistically significant differences in exacerbation rates between cycled and culture-based groups (hazard ratio, 0.95; 95% confidence interval [CI], 0.54-1.66) or ciprofloxacin and placebo (hazard ratio, 1.45; 95% CI, 0.82-2.54). The odds ratios of P aeruginosapositive culture comparing the cycled vs culture-based group were 0.78 (95% CI, 0.49-1.23) and 1.10 (95% CI, 0.71-1.71) comparing ciprofloxacin vs placebo. Adverse events were similar across groups. Conclusions: No difference in the rate of exacerbation or prevalence of P aeruginosa positivity was detected between cycled and culture-based therapies. Adding ciprofloxacin produced no benefits.
Journal of Antimicrobial Chemotherapy, 2010
Objectives: To test the presumption that Pseudomonas aeruginosa isolates responsible for initial lung infection in individuals with cystic fibrosis (CF) are invariably susceptible to antipseudomonal agents. Methods: Antibiotic susceptibility was determined (MIC and Etest) in two populations of P. aeruginosa associated with initial lung infection. Population 1: environmental isolates (n¼ 78). Population 2: clinical isolates responsible for first infection in previously non-infected patients (85 isolates from 85 patients). Susceptibility or resistance was determined using current BSAC guidelines; ninth version (2009). Results: The majority (≥90%) of isolates in both bacterial populations were susceptible to the front-line antipseudomonal agents; colistin, ciprofloxacin, tobramycin, ceftazidime, amikacin and meropenem. Up to 10% of isolates were resistant to one or more antibiotics. A single isolate from each population would be defined as resistant to tobramycin based on a breakpoint (.128 mg/L) that has been suggested for use in patients receiving inhaled therapy. Conclusions: The high prevalence of susceptibility found in P. aeruginosa isolates associated with initial infection contrasts with the high prevalence of resistance found in isolates from chronic CF lung infection. However, susceptibility in early isolates cannot be presumed. Until further data are obtained from clinically based studies, susceptibility tests should continue to be performed to assist the choice of antibiotics for treatment of early infection.
Eurasian Journal of Pulmonology, 2016
Objective: Multidrug resistance is a major problem of Pseudomonas aeruginosa strains. We aimed to determine the level of resistance to the antipseudomonal antibiotics, the change in the rates of antibiotic resistance over the years, and mortality rate during hospital stay. Methods: The microbiology database of P. aeruginosa isolated from 3708 sputum and 485 bronchial lavage samples at Chest Diseases Public Hospital from January 2009 to December 2013 was retrospectively reviewed. Imipenem, amikacin, tobramycin, ciprofloxacin, piperacillin, piperacillin/tazobactam ceftazidime, and cefepime resistance rates of P. aeruginosa strains were determined. Antimicrobial susceptibility was determined by the disk diffusion method, according to the Clinical Laboratory Standards Institute (CLSI) guidelines. P. aeruginosa was defined as resistant (resistance to at least one of the antipseudomonal antibiotics), and multidrug resistant (MDR) (resistance to three or more drugs of following classes: β-lactam, carbapenem, aminoglycoside, and fluoroquinolone). Results: Five hundred and five P. aeruginosa isolates were tested. The antibiotic resistance rates were as follows; cefepime (26.7%), ceftazidime (23.2%), piperacillin (22.2%), imipenem (21.8%), piperacillin/tazobactam (19.2%), ciprofloxacin (17.4%), tobramycin (11.9%), and amikacin (7.3%). When compared 2009 and 2013, statistically significant reduction was observed in resistance rates to ciprofloxacin, amikacin, and cefepime antibiotics. Among 505 strains, 12.1% were designated as being MDR. Out of 505 patients investigated, 34 (6.7%) died during the hospital stay. Conclusion: The clinical significance of these findings is important in the selection of appropriate empirical treatment of serious P. aeruginosa infections.
Antimicrobial Agents and Chemotherapy, 2012
Infections due to multidrug-resistant (MDR) Pseudomonas aeruginosa are increasing. The aim of our study was to evaluate the influences of appropriate empirical antibiotic therapy and multidrug resistance on mortality in patients with bacteremia due to P. aeruginosa (PAB). Episodes of PAB were prospectively registered from 2000 to 2008. MDR was considered when the strain was resistant to >3 antipseudomonal antibiotics. Univariate and multivariate analyses were performed. A total of 709 episodes of PAB were studied. MDR PAB (n ؍ 127 [17.9%]) was more frequently nosocomial and associated with longer hospitalization, bladder catheter use, steroid and antibiotic therapy, receipt of inappropriate empirical antibiotic therapy, and a higher mortality. Factors independently associated with mortality were age (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.002 to 1.033), shock (OR, 6.6; 95% CI, 4 to 10.8), cirrhosis (OR, 3.3; 95% CI, 1.4 to 7.6), intermediate-risk sources (OR, 2.5; 95% CI, 1.4 to 4.3) or high-risk sources (OR, 7.3; 95% CI, 4.1 to 12.9), and inappropriate empirical therapy (OR, 2.1; 95% CI, 1.3 to 3.5). To analyze the interaction between empirical therapy and MDR, a variable combining both was introduced in the multivariate analysis. Inappropriate therapy was significantly associated with higher mortality regardless of the susceptibility pattern, and there was a trend toward higher mortality in patients receiving appropriate therapy for MDR than in those appropriately treated for non-MDR strains (OR, 2.2; 95% CI, 0.9 to 5.4). In 47.9% of MDR PAB episodes, appropriate therapy consisted of monotherapy with amikacin. In conclusion, MDR PAB is associated with a higher mortality than non-MDR PAB. This may be related to a higher rate of inappropriate empirical therapy and probably also to amikacin as frequently the only appropriate empirical therapy given to patients with MDR PAB.
Enfermedades Infecciosas y Microbiología Clínica, 2018
Introduction: To evaluate the changes in the susceptibility of Pseudomonas aeruginosa over time (2000-2017) against antimicrobials used in an intensive care unit of a Spanish tertiary hospital, and to compare them with the antimicrobial activity considering theoretical pharmacokinetic/pharmacodynamic (PK/PD) criteria. The influence of the method for handling duplicate isolates to quantify susceptibility rates was also evaluated. Methods: The susceptibility was studied considering the Clinical and Laboratory Standards Institute (CLSI) breakpoints. Monte Carlo simulations were conducted to calculate the cumulative fraction of response (CFR). Linear regression analysis was applied to determine the trends in susceptibility and in the CFR. Results: A significant decrease in the susceptibility to gentamicin and imipenem was observed, and more recently the highest percentages of susceptible strains were found for amikacin, cephalosporins and piperacillin/tazobactam (>80%). The probability of success of an empiric treatment or CFR for most of the evaluated antimicrobials was lower than 70% during the last two-year period. Only meropenem provided high probabilities (>90%) to achieve the PK/PD target. Cephalosporins provided moderate probabilities (>80%) although for ceftazidime, the highest dose (2 g/8 h) was required. Moreover, a significant decrease in the CFR trend for ciprofloxacin, imipenem and levofloxacin was observed. Conclusions: Both susceptibility rates and CFR values have to be considered together to optimize the antimicrobial dose regimen for clinical making-decisions. They are complementary tools and, they should be used jointly in surveillance programmes. In fact, susceptibility data are not always useful to detect changes in the CFR. No relevant differences were observed among the methods for handling repeated isolates.
IP innovative publication pvt. ltd, 2019
P. aeruginosa is a gram negative rod non-fermenter bacterium that commonly cause opportunistic hospital acquired infection. The antibiotic susceptibility of bacteria frequently changes over time and differs from place to place so regular surveillance of antibiotic susceptibility in institute is needed to treat the infection empirically and efficiently. Objectives: 1) To determine frequency of respiratory tract infections by P.aeruginosa 2) To determine antimicrobial susceptibility of P. aeruginosa isolated from patients with respiratory tract infections 3) To determine antimicrobial susceptibility of P. aeruginosa isolates of respiratory tract infections in indoor versus outdoor patients 4) To determine antimicrobial susceptibility of P. aeruginosa isolates from patients with respiratory tract infections from various clinical departments. 5) To determine frequency of respiratory tract infections by multi drug resistant (MDR) P. aeruginosa Material and Methods: A total of 66 P. aeruginosa isolated from clinical specimens from patients of respiratory tract infections were included in the presents study and antibiotic susceptibility of the isolates was determined by Clinical Laboratory and Standard Institute [CLSI] guidelines. Data including patient’s age, gender, organism and antibiotic susceptibility results were collected, and analyzed using Microsoft Excel 2007, and Whonet 5.6. Results: Prevalence of P. aeruginosa in respiratory tract infections is 26%. In present study, P. aeruginosa isolates showed highest sensitivity towards Colistin (100%), followed by Meropenem (98.4%), Piperacillin/Tazobactam (98.4%), Ciprofloxacin (98.4%), Ceftazidime (93.8%), Cefoperazone (94.8%), and Amikacin (92.2%), and lowest sensitivity towards to Piperacillin (90.6%) and Ticarcillin (87.5%) observed. P. aeruginosa from indoor patients showed higher resistance towards antipseudomonal drugs than isolated from outdoor patients. There is difference in antibiotic sensitivity of P. aeruginosa isolated from different clinical departments. Out of 66 P. aeruginosa isolates, 2 (3%) were MDR. Conclusion: Difference of antibiotic sensitivity results in P. aeruginosa isolated from indoor/outdoor patients, and clinical departments like Pulmonary/Medicine/Casualty observed, therefore need to be review regularly the antimicrobial susceptibility pattern to have an opinion of clinical effect of different therapeutic drugs.
British journal of biomedical science, 2011
Pseudomonas aeruginosa is an important pathogen in humans, particularly in the context of nosocomial infection and infections of the cystic fibrosis (CF) lung. In order to provide clinicians with information about the likely effectiveness of specific antimicrobial treatment for P. aeruginosa infections, clinical laboratories employ in vitro antimicrobial susceptibility testing. Two commonly employed methods are the CLSI disc-diffusion and Etest methods. The purpose of this study is to compare the accuracy of susceptibility results generated by these two methods against agar dilution as the reference method. Susceptible or nonsusceptible (resistant and intermediate) results of the Etest and CLSI disc-diffusion methods are compared with CLSI agar dilution results for a large cohort of clinical cystic fibrosis (n = 71) and non-cystic fibrosis (n = 83) isolates using CLSI interpretive criteria. An unacceptable number of major and very major errors were observed for various antimicrobial...
SpringerPlus, 2012
The present study was conducted to determine the antibiotic susceptibility pattern of Pseudomonas aeruginosa from sputum samples of lower respiratory tract infection patients admitted to different hospitals of Karachi. Most of the hospitals are hampered with high frequency of nosocomial infections generally caused by multiresistant nosocomial pathogen. Among Gram-negative pathogens Pseudomonas aeruginosa considered as most challenging pathogen. The objective of the study was to determine frequency of Pseudomonas aeruginosa from sputum samples and to find out susceptibility pattern against four antibiotics widely used for treatment. The sputum samples from 498 patients were collected consecutively between January 2010 and March 2011 and were cultured and identified. According to CLSI (Clinical Laboratory Standards Institute) guidelines antimicrobial susceptibility testing was performed by disc diffusion method. Pseudomonas aeruginosa were isolated from 24% (120/498) of the lower respiratory tract patient. A higher resistance to Pseudomonas aeruginosa isolate was observed with piperacillin/tazobactam and cefipime i.e. 42% and 40% respectively. Imipenem was found to be most effective antibiotic against Pseudomonas aeruginosa (76% sensitivity) but amikacin resistance was continuously increasing. In conclusion the frequency of Pseudomonas aeruginosa was also higher among lower respiratory tract infection patients with alarmingly high rate of resistance among widely used antibiotics. These findings focused on careful consideration for monitoring and optimization of antimicrobial use in order to reduce occurrence and spread of antimicrobial resistant pathogen.