Pharmacodynamic profiling of commonly prescribed antimicrobial drugs against Escherichia coli isolates from urinary tract

Detection of O25b-ST131 clone, CTX-M-1 and CTX-M-15 genes via real-time PCR in Escherichia coli strains in patients with UTIs obtained from a university hospital in Istanbul

BACKGROUND

Escherichia coli sequence type 131 is an important multidrug resistant clone responsible from more than half of ESBL-producing E.coli isolates. Aim of this study was to investigate the presence of O25b-ST131 clone, CTX-M-15 and CTX-M-1 genes in the E. coli strains isolated from both hospital and community acquired UTIs by real-time PCR and to reveal molecular epidemiological data.

METHODS

Non-duplicate E. coli (n = 101) strains isolated from UTI patients were included. Bacterial identifications were performed with VITEK Compact. Antimicrobial susceptibility tests, phenotypic ESBL and E-tests were performed conventionally. Real-time PCR was utilized to detect presence of O25b-ST131 clone, blaCTX-M-15 and blaCTX-M-1.

RESULTS

O25b-ST131 clone, CTX-M-1 and CTX-M-15 were detected in 22%, 73%, 37% in UTIs, respectively. Presence of O25b-ST131 clones and CTX-M-1 genes among E. coli strains isolated from inpatients were found statistically higher than outpatients. The most effective choice was found to be fosfomycin and nitrofurantoin in outpatients and inpatients, respectively. The MIC₉₀ values of Amikacin, Cefotaxime, Cefepime and Ciprofloxacin were higher in inpatients than in oupatients, whereas Cefotaxime and Ciprofloxacin MIC₅₀ values were found to be higher in inpatients than in outpatients. The highest increase of MIC₉₀ values was observed in O25b-ST131, CTX-M-1 and CTX-M-15 coexistence.

CONCLUSION

The presence of O25b-ST131 clone, CTX-M-1 and CTX-M-15 genes in E. coli strains in patients with UTI has been revealed. In the presence of the O25b-ST131 clone, a significant increase was observed in the ciprofloxacin MIC values indicating the importance of monitorization of the clone using molecular epidemiology.

Rethinking urinary antibiotic breakpoints: analysis of urinary antibiotic concentrations to treat multidrug resistant organisms

OBJECTIVE

The present study analyzed whether renally eliminated antibiotics achieve sufficient urinary concentrations based on their pharmacokinetic/pharmacodynamic principles to effectively eradicate organisms deemed resistant by automated susceptibility testing.

RESULTS

Lower median minimum inhibitory concentrations against enterobacteriaceae were noted for ceftriaxone, cefepime, and doripenem when comparing Etest^® to Vitek^®. All Pseudomonas aeruginosa isolates were susceptible to cefepime, ciprofloxacin, and doripenem with both susceptibility methods, but higher median minimum inhibitory concentrations were observed with Etest^®. Urine concentrations/time profiles were calculated for standard doses of ceftriaxone, cefepime, doripenem, and ciprofloxacin. The data presented in the current study suggests high urine concentrations of antibiotics may effectively eradicate bacteria which were determined to be resistant per in vitro susceptibility testing.

Bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates from patients in Ndjamena, Chad

Introduction

Bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates were determined among patients in the Ndjamena General Hospital, a National Reference centre.

Methods

A cross-sectional study was carried out from July to November 2014. Six hundred and sixty patients were enrolled, to whom a cytobacteriological examination of urine was prescribed. Urine was collected and cultured. Bacterial identification and antimicrobial susceptibility patterns were performed using Vitek 2 compact automated system.

Results

216 isolates were recovered from patients (age range: 10-90 years). E. coli was the pathogen frequently cultured 128 (59.3%) followed by K. pneumonia 28 (13.0%). Bacteriuria was more present in inpatients (70.4%) compared to outpatients (29.6%). High antibiotic-resistance rate (> 60%) of the total isolates was observed with ampicillin, ciprofloxacin and cephalosporins. Imipeneme (94.9%) displayed satisfactory activity against bacteria isolates. ESBLs phenotype was present in 68/105 (64.7%) of betalactamine resistant isolates. AAC(3)-I and AAC(6’)-I enzymes were found respectively in 16/36 (44.4%) and 20/36 (55.6%) of aminoglycosides resistant isolates. Resistance of isolates to quinolones was mainly due to an association of target modification (gyrA and parC), porin reduction and/or efflux mechanisms and was present in 107/213 (49%) of quinolones resistant isolates.

Conclusion

E. coli is the predominant uropathogen isolated in our setting and there are antibiotic-resistant uropathogens among the studied population. Therefore, routine surveillance of bacterial uropathogens to common used antibiotics must be a continuous process so as to provide physicians with up to date information about the local data of antimicrobial resistance.

Infecções comunitárias do trato urinário: prevalência e susceptibilidade aos antimicrobianos na cidade de Florianópolis

Objetivo: Determinar a frequência de isolamento dos uropatógenos e avaliar o perfil de sensibilidade antimicrobiana in vitro das bactérias isoladas em uroculturas de pacientes ambulatoriais atendidos em Florianópolis no ano de 2014, correlacionando tais dados com sexo e idade do paciente. Métodos: Estudo observacional, descritivo do tipo transversal, que incluiu uroculturas positivas de pacientes ambulatoriais realizadas em um único laboratório seguindo a mesma metodologia. Realizaram-se análises de estatísticas descritivas e testes de associação entre as variáveis classificatórias: sexo, idade, agente etiológico e sensibilidade aos antimicrobianos. Resultados: Foram registradas 1035 uroculturas positivas, das quais 89,66% de pacientes femininas. Microrganismos Gram-negativos foram os patógenos mais isolados, com destaque para a Escherichia coli (77,10%), principal agente causal. Proteus mirabilis foi significativamente mais prevalente no sexo masculino e o principal microrganismo isolado nas uroculturas dos meninos de 1 a 5 anos. A E. coli foi significativamente mais prevalente no sexo feminino e apresentou o perfil mais amplo de resistência. Evidenciaram-se diferenças estatisticamente significativas nas resistências às fluoroquinolonas entre os gêneros, com maiores prevalências de resistência em homens e entre as faixas etárias, com maior resistência entre idosos. Conclusões: Idade e sexo são variáveis determinantes na frequência de isolamento dos uropatógenos e na prevalência da susceptibilidade antimicrobiana; e os microrganismos mais prevalentes já não respondem satisfatoriamente a parte dos antimicrobianos amplamente utilizados. É fundamental que o médico considere tais informações no momento da decisão terapêutica e preze pelo uso racional dos antimicrobianos, sobretudo aqueles de largo espectro como as fluoroquinolonas.

Plasma and intraprostatic concentrations of ertapenem following preoperative single dose administration: a single-centre prospective experience and clinical implications-the ERTAPRO study

The incidence of urinary tract infections caused by extended-spectrum β-lactamase (ESBL)-producing pathogens is increasing. These infections are associated with a long hospital stay in patients undergoing urological procedures. We aimed to demonstrate that significant intraprostatic diffusion of ertapenem is achieved after a single preoperative administration. A referred sample of 19 patients requiring surgery for benign prostatic hyperplasia was prospectively included. Patients received a 1 g intravenous (i.v.) dose of ertapenem 1 h (n = 10, group A) or 12 h (n = 9, group B) before blood and prostatic samples were collected. Plasma and intraprostatic concentrations of ertapenem were measured using LC-MS/MS. Intraprostatic concentrations were considered satisfactory when higher than the MIC90 value of urinary-targeted pathogens perioperatively and for 40% of the dosing interval. The Wilcoxon test and a pharmacokinetic predictive model were used. Median plasma concentrations of ertapenem were 144.3 mg/L (95% CI 126.5-157.9) in group A and 30.7 mg/L (95% CI 22.9-36.4) in group B (P < 0.001); median intraprostatic concentrations were 16.6 mg/L (95% CI 13.3-31.4 mg/L) and 4.2 mg/L (95% CI 3.1-4.9 mg/L), respectively (P < 0.001), which were above the MIC90 values of bacteria, including ESBL-producers, during surgery and for 40% of the dosing interval. The plasma-to-prostate concentration ratio was not significantly different between groups (P = 0.97). Single-dose i.v. ertapenem reached satisfactory intraprostatic concentrations, suggesting that it could be a relevant prophylactic strategy for carriers of ESBL-producing bacteria undergoing prostatic procedures, which needs to be confirmed by further prospective trials.