In vitro susceptibility to fosfomycin in clinical and environmental extended-spectrum beta-lactamase producing and/or ciprofloxacin-non-susceptible Escherichia coli isolates

ABSTRACT Extended-spectrum beta-lactamase producing and ciprofloxacin-non-susceptible Escherichia coli are clinical and environmental issues. We evaluated the susceptibility profile of fosfomycin in non-susceptible E. coli isolated from urine and the environment. We measured the activity of fosfomycin against 319 and 36 E. coli strains from urine and environmental isolates, respectively, collected from rivers. Fosfomycin resistance profiles were investigated using the minimal inhibitory concentration (MIC), according to the Clinical and Laboratory Standards Institute (CLSI) and the European Committee for Antimicrobial Susceptibility Testing (EUCAST) guidelines. Antibiotic susceptibility testing revealed that 5% and 6.6% of urine samples were non-susceptible to fosfomycin according to CLSI and EUCAST guidelines, respectively. The fosfomycin MIC50/90 was 0.5/4 mg/L. Of the 36 E. coli isolates from river water, 11.1% and 13,8% were non-susceptible to fosfomycin according to CLSI and EUCAST, respectively (range ≤0.25 ≥512 mg/L). All the isolates with MIC ≥512 mg/L for fosfomycin showed the fosA3 gene. Fosfomycin resistance was more frequent in the environment than in clinical samples.

Validation of multiplex PCR for the diagnosis of acute bacterial meningitis in culture negative cerebrospinal fluid / Validação do PCR multiplex para o diagnóstico de meningite bacteriana aguda com cultura de liquido cefalorraquidiano negativa

ABSTRACT This study evaluated the operational characteristics of the multiplex polymerase chain reaction (PCR) for cerebrospinal fluid (CSF) from patients with cellular and biochemical characteristics of acute bacterial meningitis and positive or negative CSF cultures. Methods: Multiplex PCR was performed for 36 CSF samples: culture-proven acute bacterial meningitis (n = 7), culture-negative acute bacterial meningitis (n = 17), lymphocytic meningitis (n = 8), and normal CSF (n = 4). The operational characteristics of multiplex PCR were evaluated with definite and probable bacterial meningitis, using culture positive, cytological and biochemical CSF characteristics as the gold standard. Results: Multiplex PCR for CSF was efficient in the group with CSF cellular and biochemical characteristics of acute bacterial meningitis but with a negative CSF culture. This group demonstrated high specificity, positive predictive value, and efficiency. Conclusions: Multiplex PCR for CSF can improve the speed and accuracy of acute bacterial meningitis diagnosis in a clinical setting as a complement to classical immunological and bacteriological assays in CSF. It is also useful for CSF culture-negative acute bacterial meningitis.

RESUMO Este estudo avaliou as características funcionais da reação em cadeia da polimerase (PCR) multiplex para amostras de líquido cefalorraquidiano (LCR) de pacientes com características celulares e bioquímicas de meningite bacteriana aguda e culturas de LCR positivas ou negativas. Métodos: O PCR multiplex foi realizado em 36 amostras de LCR: meningite bacteriana aguda comprovada por cultura (n = 7), meningite bacteriana aguda com cultura negativa (n = 17), meningite linfocítica (n = 8) e LCR normal (n = 4). As características funcionais do PCR multiplex foram avaliadas para meningite bacteriana definitiva e provável, utilizando cultura positiva, características citológicas e bioquímicas do LCR como padrão-ouro. Resultados: O PCR multiplex do LCR foi eficiente no grupo com características celulares e bioquímicas do LCR de meningite bacteriana, mas com cultura do LCR negativa. Este grupo demonstrou especificidade, valor preditivo positivo e eficiência altos. Conclusões: Os autores concluíram que o PCR multiplex do LCR pode melhorar a velocidade e a precisão do diagnóstico de meningite bacteriana em um ambiente clínico como complemento aos ensaios imunológicos e bacteriológicos clássicos no LCR. Também é útil para meningite bacteriana aguda com cultura de LCR negativa.

Risk factors for mortality in patients with ventilator-associated pneumonia caused by carbapenem-resistant Enterobacteriaceae

Abstract Background: The ideal therapeutic option for ventilator associated pneumonia caused by carbapenem-resistant Enterobacteriaceae is not defined. The aim of this study was to assess mortality-associated risk factors in patients with VAP by CRE and determine the outcome of several treatment options. Methods: This was a retrospective study performed in two tertiary hospitals involving patients with VAP caused by CRE between January 2010 and August 2014. The outcomes were mortality within 30 days of VAP diagnosis and overall mortality during hospital admission. Risk factors for mortality were assessed by comparing variables of survivors and non-survivors. Results: One hundred and twelve patients with CRE-VAP were included, 73 (65%) male, median age 56 years. The 30-day mortality was 57.1% and the overall hospital mortality was 67%. In the binary logistic regression analysis, only age >50 years was independently associated to increased mortality. Polymyxin was the most used drug (47.5%), followed by tigecycline (29.2%) and aminoglycosides (2.4%). Combined therapy with two active drugs was used by 17 patients (20.8%). No therapeutic option was independently associated to survival. However, combined therapy with two active drugs was superior to the therapy with a single active drug when inappropriate therapy was the comparator (p = 0.044). The addition of carbapenem was not associated with increased survival. Conclusion: The best therapeutic option for VAP by CRE is still not completely defined, but the therapy with at least two active drugs was superior in this study.

Validação do teste de inibição pelo ácido aminofenilborônico para triagem de Klebsiella pneumoniae carbapenemases (KPC) / Validation of inhibition test by aminophenyl boronic acid to Klebsiella pneumoniae carbapenemases (KPC) screening

INTRODUÇÃO: A produção de enzimas Klebsiella pneumoniae carbapenemase (KPC) tem se tornado um importante e preocupante mecanismo de resistência, e ensaios que combinem alta sensibilidade e alta especificidade para a detecção dessas enzimas são escassos. OBJETIVO: Validar o teste de inibição pelo ácido 3-aminofenilborônico como método de triagem fenotípica de cepas produtoras de enzima KPC, comparando os resultados obtidos com os de testes confirmatórios por reação em cadeia da polimerase (PCR). METODOLOGIA: Avaliou-se o uso do ácido 3-aminofenilborônico impregnado em discos de antibióticos de imipenem, meropenem e ertapenem. Foram testadas 36 cepas positivas e 12 negativas, todas confirmadas por PCR. Foram ainda testadas três concentrações diferentes de ácido borônico: 300, 400 e 600 µg. RESULTADOS: Entre as cepas positivas testadas, o resultado mais adequado se deu com a adição do composto em disco contendo ertapenem, com especificidade de 100%, porém com sensibilidade de apenas 50%. CONCLUSÃO: Novos estudos são necessários, sobretudo no que diz respeito à padronização da técnica e aos insumos utilizados, pois o método se revela promissor na triagem de cepas produtoras de KPC.

INTRODUCTION: The production of Klebsiella pneumoniae carbapenemases enzymes (KPC) has become an important and worrisome resistance mechanism. Furthermore, tests that combine high sensitivity and high specificity for the detection of these enzymes are scarce. OBJECTIVE: To validate the inhibition test by 3-aminophenyl boronic acid as a phenotypic screening method for KPC-producing strains by comparing the results with confirmatory polymerase chain reaction testing (PCR). METHODS: We evaluated the use of 3-aminophenyl boronic acid applied on disks with imipenem, meropenem and ertapenem antibiotics. 36 strains were positive and 12 were negative, all confirmed by PCR. Three different concentrations of boronic acid were also tested: 300, 400 and 600 µg. RESULTS: Among the positive strains, the results were more accurate with the addition of the compound to the ertapenem disk, presenting 100 % specificity and 50% sensitivity. CONCLUSION: Further studies are required, mainly regarding the standardization of the technique and materials, since the method seems to be promising as to the screening of KPC strains.

Risk factors for KPC-producing Klebsiella pneumoniae bacteremia

The molecular epidemiology of carbapenemase-producing Klebsiella pneumoniae (KPC) has been largely investigated, but limited clinical information is available. A case-control study was performed to evaluate the risk factors for KPC bacteremia in hospitalized patients. Cases were patients with KPC bacteremia and controls were patients with non-KPC bacteremia. A total of 85 patients were included, 18 (21.2%) were KPC, and 67 (78.8%) were non-KPC (40 [59.7%] of them were extended-spectrum beta-lactamase producers). All KPC isolates were type 2 producers. These isolates belong to five distinct clones. Multivariate analysis showed that age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02 - 1.11; p = 0.004), presence of mechanical ventilation (OR, 11.1; 95% CI, 1.92 - 63.3; p = 0.007) and fluoroquinolone exposure during hospitalization (OR, 28.9; 95% CI, 1.85 - 454.6; p = 0.02) were independent risk factors for KPC in patients with K. pneumoniae bacteremia. Factors associated with severity of illness, such as age and mechanical ventilation, seem to be the main risks factors for KPC. Fluoroquinolones use might be a risk factor for KPC bacteremia. Further investigations on risk factors for KPC are warranted.