El papel del laboratorio de microbiología en el diagnóstico de infecciones por bacilos gramnegativos multirresistentes. Importancia de la determinación de mecanismos de resistencias / The role of the microbiology laboratory in the diagnosis of multidrug-resistant Gram-negative bacilli infections. Importance of the determination of resistance mechanisms

Un diagnóstico y tratamiento precoz tiene un impacto importante en la morbimortalidad de las infecciones producidas por bacterias multirresistentes. Los bacilos gramnegativos multirresistentes constituyen la principal amenaza actual en los hospitales y muy especialmente en las unidades de cuidados intensivos. El papel del laboratorio de microbiología es esencial en dar una respuesta rápida y eficaz. En esta revisión se actualiza los procedimientos del laboratorio de microbiología para la detección rápida de los bacilos gramnegativos multirresistentes y de sus determinantes de resistencia. También se estudia el papel del laboratorio en la vigilancia y control de brotes por estas bacterias, incluyendo las técnicas de tipificación. Se destaca la importancia de proporcionar mapas de resistencia normalizados que permitan conocer la situación epidemiológica de las diferentes unidades. Finalmente se revisa la importancia de sistemas de comunicación eficaces para la transmisión de resultados y la toma de decisiones en el manejo de pacientes infectados por bacilos gramnegativos multirresistentes (AU)

Early diagnosis and treatment has an important impact on the morbidity and mortality of infections caused by multidrug-resistant bacteria. Multidrug-resistant gram-negative bacilli constitute the main current threat in hospitals and especially in intensive care units. The role of the microbiology laboratory is essential in providing a rapid and effective response. This review updates the microbiology laboratory procedures for the rapid detection of multidrug-resistant gram-negative bacilli and its resistance determinants. The role of the laboratory in the surveillance and control of outbreaks caused by these bacteria, including typing techniques, is also studied. The importance of providing standardized resistance maps that allow knowing the epidemiological situation of the different units is emphasized. Finally, the importance of effective communication systems for the transmission of results and decision making in the management of patients infected by multidrug-resistant gram-negative bacilli is reviewed (AU)

The role of the microbiology laboratory in the diagnosis of multidrug-resistant Gram-negative bacilli infections. The importance of the determination of resistance mechanisms.

Early diagnosis and treatment has an important impact on the morbidity and mortality of infections caused by multidrug-resistant bacteria. Multidrug-resistant gram-negative bacilli (MR-GNB) constitute the main current threat in hospitals and especially in intensive care units (ICU). The role of the microbiology laboratory is essential in providing a rapid and effective response. This review updates the microbiology laboratory procedures for the rapid detection of BGN-MR and its resistance determinants. The role of the laboratory in the surveillance and control of outbreaks caused by these bacteria, including typing techniques, is also studied. The importance of providing standardized resistance maps that allow knowing the epidemiological situation of the different units is emphasized. Finally, the importance of effective communication systems for the transmission of results and decision making in the management of patients infected by BGN-MR is reviewed.

Association of blaOXA-1, and aac(6')-Ib-cr with ST405 K. pneumoniae clone / Asociación de los genes blaOXA-1 y aac(6')-Ib-cr con el clon ST405 de K. pneumoniae

No disponible

Vagino-rectal colonization and maternal-neonatal transmission of Enterobacteriaceae producing extended-spectrum ß-lactamases or carbapenemases: a cross-sectional study.

This study sought to determine the prevalence and risk factors for colonization with extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) and carbapenemase-producing Enterobacteriaceae (CPE) in 815 mothers and 800 newborns using a cross-sectional design; 59 women and 13 neonates were colonized by ESBL-E (prevalence (95% confidence interval): 6.7% (5.2-8.7) and 1.6 (0.7-2.5), respectively). No CPE were found. The most frequent ESBL-E were CTX-M-14 and SHV-12. Vertical transmission occurred in 14% of colonized mothers. The risk factors for colonization were, in mothers: complications in previous pregnancies, more than one urinary tract infection, non-Caucasian ethnicity, and frequently having the main meal outside home; in newborns: colonized mother and vaginal delivery.

Prevalence and transmission dynamics of Escherichia coli ST131 among contacts of infected community and hospitalized patients.

OBJECTIVES: The Escherichia coli O25b-associated ST131 clonal group was recently found to be prevalent in our area as a cause of community-acquired urinary tract infections. We evaluated the transmission dynamics and longitudinal persistence of E. coli O25b-ST131 between patients with nosocomial and community-acquired infections and their contacts. METHODS: Prevalence and transmission of O25b/pabB3/B23 isolates were compared in 38 community clusters, 30 nosocomial clusters and 50 healthy volunteers. Duration of colonization was studied at 1 to 4 months and 6 to 12 months after the first sample. Isolates exhibiting a three-band or less difference by pulsed-field gel electrophoresis were assigned to the same pulsotype. RESULTS: Colonization was found to be more frequent in index cases (31/68, 45.6%) than in contacts (25/118, 21.2%; p 0.0009) or volunteers (1/50, 2%; p 0.0009). Seven (11%) of 64 isolates were extended-spectrum ß-lactamase producers. Transmission occurred in 61% (8/13) community clusters and in 12% (1/8) nosocomial clusters. Thirteen (56.5%) of the 23 initial carriers assessed at 1 to 4 months remained colonized. Only 2 (13.3%) of 15 positive patients followed for 6 to 12 months showed prolonged carriage, and none was infected with extended-spectrum ß-lactamase producers. Six previously positive individuals acquired a different ST131 pulsotype (5/23 at sample 2 and 1/15 at sample 3), and three previously negative individuals became positive (2/46 at 1-4 months and 1/33 at 6-12 months). CONCLUSIONS: Person-to-person transmission or acquisition from a common source of E. coli O25b-associated ST131 is more frequent in the household setting than in the nosocomial setting. The carrier state does not usually last beyond 4 months, with new acquisitions in certain individuals.

Modelling the epidemiology of Escherichia coli ST131 and the impact of interventions on the community and healthcare centres.

ST131 Escherichia coli is an emergent clonal group that has achieved successful worldwide spread through a combination of virulence and antimicrobial resistance. Our aim was to develop a mathematical model, based on current knowledge of the epidemiology of ESBL-producing and non-ESBL-producing ST131 E. coli, to provide a framework enabling a better understanding of its spread within the community, in hospitals and long-term care facilities, and the potential impact of specific interventions on the rates of infection. A model belonging to the SEIS (Susceptible-Exposed-Infected-Susceptible) class of compartmental models, with specific modifications, was developed. Quantification of the model is based on the law of mass preservation, which helps determine the relationships between flows of individuals and different compartments. Quantification is deterministic or probabilistic depending on subpopulation size. The assumptions for the model are based on several developed epidemiological studies. Based on the assumptions of the model, an intervention capable of sustaining a 25% reduction in person-to-person transmission shows a significant reduction in the rate of infections caused by ST131; the impact is higher for non-ESBL-producing ST131 isolates than for ESBL producers. On the other hand, an isolated intervention reducing exposure to antimicrobial agents has much more limited impact on the rate of ST131 infection. Our results suggest that interventions achieving a continuous reduction in the transmission of ST131 in households, nursing homes and hospitals offer the best chance of reducing the burden of the infections caused by these isolates.

The global threat of antimicrobial resistance: science for intervention.

In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.

Corrigendum to "The global threat of antimicrobial resistance: science for intervention" [New Microbes New Infect 6 (2015): 22-29].

[This corrects the article DOI: 10.1016/j.nmni.2015.02.007.].

Inoculum effect on the efficacies of amoxicillin-clavulanate, piperacillin-tazobactam, and imipenem against extended-spectrum ß-lactamase (ESBL)-producing and non-ESBL-producing Escherichia coli in an experimental murine sepsis model.

Escherichia coli is commonly involved in infections with a heavy bacterial burden. Piperacillin-tazobactam and carbapenems are among the recommended empirical treatments for health care-associated complicated intra-abdominal infections. In contrast to amoxicillin-clavulanate, both have reduced in vitro activity in the presence of high concentrations of extended-spectrum ß-lactamase (ESBL)-producing and non-ESBL-producing E. coli bacteria. Our goal was to compare the efficacy of these antimicrobials against different concentrations of two clinical E. coli strains, one an ESBL-producer and the other a non-ESBL-producer, in a murine sepsis model. An experimental sepsis model {~5.5 log10 CFU/g [low inoculum concentration (LI)] or ~7.5 log(10) CFU/g [high inoculum concentration (HI)]} using E. coli strains ATCC 25922 (non-ESBL producer) and Ec1062 (CTX-M-14 producer), which are susceptible to the three antimicrobials, was used. Amoxicillin-clavulanate (50/12.5 mg/kg given intramuscularly [i.m.]), piperacillin-tazobactam (25/3.125 mg/kg given intraperitoneally [i.p.]), and imipenem (30 mg/kg i.m.) were used. Piperacillin-tazobactam and imipenem reduced spleen ATCC 25922 strain concentrations (-2.53 and -2.14 log10 CFU/g [P < 0.05, respectively]) in the HI versus LI groups, while amoxicillin-clavulanate maintained its efficacy (-1.01 log10 CFU/g [no statistically significant difference]). Regarding the Ec1062 strain, the antimicrobials showed lower efficacy in the HI than in the LI groups: -0.73, -1.89, and -1.62 log10 CFU/g (P < 0.05, for piperacillin-tazobactam, imipenem, and amoxicillin-clavulanate, respectively, although imipenem and amoxicillin-clavulanate were more efficacious than piperacillin-tazobactam). An adapted imipenem treatment (based on the time for which the serum drug concentration remained above the MIC obtained with a HI of the ATCC 25922 strain) improved its efficacy to -1.67 log10 CFU/g (P < 0.05). These results suggest that amoxicillin-clavulanate could be an alternative to imipenem treatment of infections caused by ESBL- and non-ESBL-producing E. coli strains in patients with therapeutic failure with piperacillin-tazobactam.

Impact of changes in CLSI and EUCAST breakpoints for susceptibility in bloodstream infections due to extended-spectrum ß-lactamase-producing Escherichia coli.

The impact of recent changes in and discrepancies between the breakpoints for cephalosporins and other antimicrobials, as determined by CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST), was analysed in patients with bloodstream infections caused by extended-spectrum ß-lactamase (ESBL) producing Escherichia coli in Spain, was analysed. We studied a cohort of 191 episodes of bloodstream infection caused by ESBL-producing E. coli in 13 Spanish hospitals; the susceptibility of isolates to different antimicrobials was investigated by microdilution and interpreted according to recommendations established in 2009 and 2010 by CLSI, and in 2011 by EUCAST. Overall, 58.6% and 14.7% of isolates were susceptible to ceftazidime, and 35.1% and 14.7% to cefepime using the CLSI-2010 and EUCAST-2009/2011 recommendations, respectively (all isolates would have been considered resistant using the previous guidelines). Discrepancies between the CLSI-2010 and the EUCAST-2011 recommendations were statistically significant for other antimicrobials only in the case of amikacin (98.4% versus 75.9% of susceptible isolates; p <0.01). The results varied depending on the ESBL produced. No significant differences were found in the percentage of patients classified as receiving appropriate therapy, following the different recommendations. Four out of 11 patients treated with active cephalosporins according to CLSI-2010 guidelines died (all had severe sepsis or shock); these cases would have been considered resistant according to EUCAST-2011. In conclusion, by using current breakpoints, extended-spectrum cephalosporins would be regarded as active agents for treating a significant proportion of patients with bloodstream infections caused by ESBL-producing E. coli.

Assessment of the presence of extended-spectrum beta-lactamase-producing Escherichia coli in eggshells and ready-to-eat products.

The principal objective of this study was to assess whether chicken eggshells may be contaminated by ESBL-producing E. coli (ESBLC). Additional analyses were carried out to determine if ESBLEC could be detected in other foodstuffs such as cooked poultry or fresh vegetables. Seventy-two eggshells from different supermarkets and stores as well as 32 salads, 30 samples of cooked poultry and six samples of chicken-based pet food samples were analysed. Characterization of ESBL was performed by PCR and sequencing. Antimicrobial resistance was determined by disk diffusion method. Phylogenetic group was assigned by multiplex-PCR. No ESBLEC was isolated from chicken eggshells, cooked chicken and pet food. One SHV-12-producing E. coli was isolated from a salad sample. This is the first study to analyse chicken eggs in an area where there is a high prevalence of ESBLEC in retail chicken meat.

Guidelines for the prevention of invasive mould diseases caused by filamentous fungi by the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC).

Invasive fungal infections (IFIs) caused by filamentous fungi still have high rates of mortality, associated with difficulties in early detection of the infection and therapeutic limitations. Consequently, a useful approach is to prevent patients at risk of fungal infection from coming into contact with conidia of Aspergillus and other mould species. This document describes the recommendations for preventing IFI caused by filamentous fungi worked out by Spanish experts from different medical and professional fields. The article reviews the incidence of IFI in different risk populations, and questions related to environmental measures for prevention, control of hospital infections, additional procedures for prevention, prevention of IFI outside of hospital facilities and antifungal prophylaxis are also analysed.

Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates.

A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with beta-lactamase production in extended-spectrum beta-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8:1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2:1 and 4:1) increased

Extended-spectrum and CMY-type beta-lactamase-producing Escherichia coli in clinical samples and retail meat from Pittsburgh, USA and Seville, Spain.

Infections due to Escherichia coli producing extended-spectrum beta-lactamase (ESBL) or CMY-type beta-lactamase (CMY) are increasingly observed in non-hospitalized patients. The origin of these organisms is uncertain, but retail meat contaminated with E. coli may be a source. In the present study, clinical information and strains collected from patients infected or colonized with ESBL-producing and CMY-producing E. coli at hospitals in Pittsburgh, USA and Seville, Spain were investigated. Retail meat purchased in these cities was also studied for the presence of these organisms. Twenty-five and 79 clinical cases with ESBL-producing E. coli and 22 cases and one case with CMY-producing E. coli were identified in Pittsburgh and Seville, respectively. Among them all, community-acquired and healthcare-associated cases together constituted 60% of the cases in Pittsburgh and 73% in Seville. Community-acquired cases were more common in Seville than in Pittsburgh (49% vs. 13%; p <0.001). ESBL-producing and CMY-producing E. coli isolates were commonly recovered from the local retail meat. In particular, 67% (8/12) of retail chickens in Seville and 85% (17/20) of those in Pittsburgh contained ESBL-producing and CMY-producing E. coli isolates, respectively. Among the ESBL-producing isolates, CTX-M and SHV were the most common ESBL types in both clinical and meat isolates. Approximately half of the ESBL-producing and CMY-producing E. coli isolates from meat belonged to phylogenetic groups associated with virulent extra-intestinal infections in humans. Community and healthcare environments are now significant reservoirs of ESBL-producing and CMY-producing E. coli. Retail meat is a potential source of these organisms.

Fatal levofloxacin failure in treatment of a bacteremic patient infected with Streptococcus pneumoniae with a preexisting parC mutation.

The fatal outcome of levofloxacin treatment in a patient with bacteremic pneumonia caused by Streptococcus pneumoniae with a preexisting parC mutation is reported. Failure was due to the emergence of a gyrA mutation after 4 days of therapy. Problems encountered in detecting first-step mutation isolates are discussed.