Rapid antibiotic susceptibility testing (RAST) of blood cultures in enterobacteria with inducible chromosomal AmpC-type ß-lactamase.

INTRODUCTION: Early and adequate treatment of bloodstream infections decreases patient morbidity and mortality. The objective is to develop a preliminary method for rapid antibiotic susceptibility testing (RAST) in enterobacteria with inducible chromosomal AmpC. METHODS: RAST was performed directly on spiked blood cultures of 49 enterobacteria with inducible chromosomal AmpC. Results were read at 4, 6 and 8h of incubation. Commercial broth microdilution was considered the reference method. Disks of 10 antibiotics were evaluated. RESULTS: The proportion of readable tests at 4h was 85%. All RAST could be read at 6 and 8h. For most antibiotics, the S or R result at 4, 6 and 8h was greater than 80% after tentative breakpoints were established and Area of Technical Uncertainty was defined. CONCLUSIONS: This preliminary method seems to be of practical use, although it should be extended to adjust the breakpoints and differentiate them by species.

Community Emergence of Cefixime-Resistant Escherichia coli Belonging to ST12 with Chromosomal AmpC Hyperproduction.

Escherichia coli isolates that are resistant to cefixime and amoxicillin/clavulanic acid, but apparently susceptible to cefuroxime, with no ESBL identified, were initially detected in Madrid from urine samples in 2019. Throughout 2020 and 2021, all cases of community UTI by E. coli from six health areas in Madrid were studied. A representative sample of 23 cases was selected for further studies. The broth microdilution method and the agar diffusion method were performed to determine the antibiotic susceptibility. WGS was carried out for phylogeny, resistome and virulome analysis. Community consumption of third-generation oral cephalosporins in Madrid (2017-2021) was analyzed. A total of 582 (1.3%) E. coli isolates had the mentioned resistance profile. The mutation at position -32 (T > A) of the AmpC promoter was found in 21 isolates. No plasmid AmpC- or ESBL-encoding genes were detected. A cluster of 20 ST12 isolates was detected by cgMLST. A 6.2% increase in the consumption of third-generation oral cephalosporins, especially cefixime, was observed in Madrid. Chromosomal AmpC-hyperproducing ST12 E. coli isolates could be implicated in the increase in community UTI cases by cefixime-resistant isolates, which correlates with an increasing trend of cefixime consumption.

Prevalence of fosA3 Gene in Fosfomycin-Resistant Proteus mirabilis in the Autonomous Community of Madrid (Spain) and Characterization of Two Positive Strains.

Plasmid-mediated resistance to fosfomycin has been seldom described in Proteus mirabilis. We report two strains harboring fosA3 gene. Whole-genome sequencing revealed a plasmid that encoded fosA3 gene flanked by two insertion sequence (IS)26 mobile elements. Both strains also produced the blaCTX-M-65 gene that was located in the same plasmid. The sequence detected was IS1182-blaCTX-M-65-orf1-orf2-IS26-IS26-fosA3-orf1-orf2-orf3-IS26. The importance of this transposon lies in its ability to spread in Enterobacterales, therefore, epidemiological surveillance should be carried out.

A Prospective Study of the Serological, Clinical, and Epidemiological Features of a SARS-CoV-2 Positive Pediatric Cohort.

Background: SARS-CoV-2 was a global pandemic. Children develop a mild disease and may have a different rate of seroconversion compared to adults. The objective was to determine the number of seronegative patients in a pediatric cohort. We also reviewed the clinical−epidemiological features associated with seroconversion. Methods: A multicenter prospective observational study during September−November 2020, of COVID-19, confirmed by reverse transcription-polymerase chain reaction. Data were obtained 4−8 weeks after diagnosis. Blood samples were collected to investigate the humoral response, using three different serological methods. Results: A total of 111 patients were included (98 symptomatic), 8 were admitted to hospital, none required an Intensive Care Unit visit. Median age: 88 months (IQR: 24−149). Median time between diagnosis and serological test: 37 days (IQR: 34−44). A total of 19 patients were non-seroconverters when using three serological techniques (17.1%; 95% CI: 10.6−25.4); most were aged 2−10 years (35%, p < 0.05). Univariate analysis yielded a lower rate of seroconversion when COVID-19 confirmation was not present amongst household contacts (51.7%; p < 0.05). Conclusions: There was a high proportion of non-seroconverters. This is more commonly encountered in childhood than in adults. Most seronegative patients were in the group aged 2−10 years, and when COVID-19 was not documented in household contacts. Most developed a mild disease. Frequently, children were not the index case within the family.

What's new in mechanisms of antibiotic resistance in bacteria of clinical origin?

The discovery, commercialization and administration of antibiotics revolutionized the world of medicine in the middle of the last century, generating a significant change in the therapeutic paradigm of the infectious diseases. Nevertheless, this great breakthrough was soon threatened due to the enormous adaptive ability that bacteria have, through which they are able to develop or acquire different mechanisms that allow them to survive the exposure to antibiotics. We are faced with a complex, multifactorial and inevitable but potentially manageable threat. To fight against it, a global and multidisciplinary approach is necessary, based on the support, guidance and training of the next generation of professionals. Nevertheless, the information published regarding the resistance mechanisms to antibiotics are abundant, varied and, unfortunately, not always well structured. The objective of this review is to structure the, in our opinion, most relevant and novel information regarding the mechanisms of resistance to antibiotics that has been published from January 2014 to September 2019, analysing their possible clinical and epidemiological impact.

Prevalence, detection and characterisation of fosfomycin-resistant Escherichia coli strains carrying fosA genes in Community of Madrid, Spain.

OBJECTIVES: The aim of this this study was to describe the presence of different variants of the fosA gene in fosfomycin-resistant Escherichia coli strains in Madrid, Spain. METHODS: fos genes were searched for in 55 E. coli strains collected from seven representative hospitals located in Madrid. A phenotypic screening test was performed following the disk diffusion method with sodium phosphonoformate added as described by Nakamura et al. Additionally, a molecular study based on PCR was used to confirm the screening results. Positive strains for fos genes were further subjected to whole-genome sequencing (WGS). RESULTS: Phenotypic screening was positive in 9/55 strains (16.4%), although genotypic detection was positive in only 3 (fosA3, fosA4 and fosA6). Thus, the prevalence of fos genes in Madrid was 5.5% (3/55). WGS data were not available for the fosA6-positive strain. One isolate with fosA3 (ST69) carried a blaCTX-M-55 gene and seven virulence genes (air, eilA, iha, iss, lpfA, sat and senB). The fosA4-positive isolate (ST4038) carried the virulence genes iss, lpfA, iroN and mchF. Both fos genes were located between two IS26 mobile elements of a plasmid. CONCLUSION: We detected the presence of different variants of plasmid-mediated fosA genes in fosfomycin-resistant E. coli strains in Madrid, Spain. Despite the few reports in Europe, it would be of interest to monitor the spread of these acquired resistance genes.

Mechanisms of Linezolid Resistance Among Enterococci of Clinical Origin in Spain-Detection of optrA- and cfr(D)-Carrying E. faecalis.

The mechanisms of linezolid resistance among 13 E. faecalis and 6 E. faecium isolates, recovered from six Spanish hospitals during 2017-2018, were investigated. The presence of acquired linezolid resistance genes and mutations in 23S rDNA and in genes encoding for ribosomal proteins was analyzed by PCR and amplicon sequencing. Moreover, the susceptibility to 18 antimicrobial agents was investigated, and the respective molecular background was elucidated by PCR-amplicon sequencing and whole genome sequencing. The transferability of the linezolid resistance genes was evaluated by filter-mating experiments. The optrA gene was detected in all 13 E. faecalis isolates; and one optrA-positive isolate also carried the recently described cfr(D) gene. Moreover, one E. faecalis isolate displayed the nucleotide mutation G2576T in the 23S rDNA. This mutation was also present in all six E. faecium isolates. All linezolid-resistant enterococci showed a multiresistance phenotype and harbored several antimicrobial resistance genes, as well as many virulence determinants. The fexA gene was located upstream of the optrA gene in 12 of the E. faecalis isolates. Moreover, an erm(A)-like gene was located downstream of optrA in two isolates recovered from the same hospital. The optrA gene was transferable in all but one E. faecalis isolates, in all cases along with the fexA gene. The cfr(D) gene was not transferable. The presence of optrA and mutations in the 23S rDNA are the main mechanisms of linezolid resistance among E. faecalis and E. faecium, respectively. We report the first description of the cfr(D) gene in E. faecalis. The presence of the optrA and cfr(D) genes in Spanish hospitals is a public health concern.

Escherichia coli resistant to fosfomycin from urinary tract infections: Detection of the fosA3 gene in Spain.

OBJECTIVES: The aim of this study was to report the epidemiological and genetic background of fosfomycin-resistant Escherichia coli isolates causing urinary tract infections (UTIs) in Spain. METHODS: A retrospective observational study of 39 randomly selected fosfomycin-resistant E. coli from urine samples collected during 2017 in Getafe (Spain) was performed. Medical records of 39 patients were reviewed. Phylogenetic groups were identified and the pandemic E. coli ST131 and clades thereof were sought by PCR and multilocus sequence typing (MLST). Screening and identification of fos genes and determination of their genetic environment (linkage to IS26) was performed by PCR. RESULTS: Of the 39 E. coli strains, 49% were ESBL-producers. Most of the strains belonged to phylogenetic group B2 (23/39; 59%), and all of these belonged to ST131 but to different clades (20 to clade C and 3 to clade B). Two isolates from phylogenetic group A (both ST10) carried a plasmid-borne fosA3 gene flanked by IS26. Of the 39 patients, 31 were female (mean age 78 years) and 8 were male (mean age 71 years). Moreover, 27 patients (69%) were diagnosed with complicated UTIs and the remaining 12 (31%) had uncomplicated UTIs, and 33 patients (85%) had been previously treated with fosfomycin. CONCLUSION: This study shows that fosfomycin-resistant E. coli strains are mainly isolated from elderly people with complicated UTIs and belong to the pandemic ST131 clone. To our knowledge, here we describe the fosA3 gene for the first time in Spain, which alerts for potential future dissemination that should be monitored.

Recommendations of the Spanish Antibiogram Committee (COESANT) for selecting antimicrobial agents and concentrations for in vitro susceptibility studies using automated systems.

Automated antimicrobial susceptibility testing devices are widely implemented in clinical microbiology laboratories in Spain, mainly using EUCAST (European Committee on Antimicrobial Susceptibility Testing) breakpoints. In 2007, a group of experts published recommendations for including antimicrobial agents and selecting concentrations in these systems. Under the patronage of the Spanish Antibiogram Committee (Comité Español del Antibiograma, COESANT) and the Study Group on Mechanisms of Action and Resistance to Antimicrobial Agents (GEMARA) from the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), and aligned with the Spanish National Plan against Antimicrobial Resistance (PRAN), a group of experts have updated this document. The main modifications from the previous version comprise the inclusion of new antimicrobial agents, adaptation of the ranges of concentrations to cover the EUCAST breakpoints and epidemiological cut-off values (ECOFFs), and the inference of new resistance mechanisms. This proposal should be considered by different manufacturers and users when designing new panels or cards. In addition, recommendations for selective reporting are also included. With this approach, the implementation of EUCAST breakpoints will be easier, increasing the quality of antimicrobial susceptibility testing data and their microbiological interpretation. It will also benefit epidemiological surveillance studies as well as the clinical use of antimicrobials aligned with antimicrobial stewardship programs.

ESBL-producing-multidrug resistant E. coli population from urinary tract infections is less diverse than non-ESBL-multidrug resistant population.

OBJECTIVE: The aim of this study was to compare the population structure of three different representative groups of E. coli isolates causing urinary tract infections in a large area of Madrid, Spain: two groups of multidrug resistant isolates (MDR), ESBL- and non-ESBL producers, and one of fully-susceptible isolates (35 isolates in each group). METHODS: Epidemiological relatedness was studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The presence of genes encoding ESBL was determined by using PCR and sequencing. Antimicrobial susceptibility testing was performed by broth microdilution. RESULTS: PFGE analysis revealed a high degree of genetic diversity in susceptible and non-ESBL-MDR groups. However, the ESBL-MDR E. coli population was less diverse and a large cluster consisting of ST131 and CTX-M-15-producing isolates was detected. CONCLUSIONS: The present study revealed that ESBL-producing-MDR E. coli population was less diverse than the non-ESBL MDR group and that ST131 was dominant among CTX-M-15-producing isolates that reflects the spread of this successful MDR lineage.

Stratification by demographic and clinical data of the antibiotic susceptibility of Escherichia coli from urinary tract infections of the community.

AIM: To determine the patterns of antibiotic susceptibility of Escherichia coli strains isolated from adult patients with urinary tract infection (UTI), and to stratify the results by age and type of UTI to verify if there are statistically significant differences that can help physicians to prescribe better empirical antibiotherapy. DESIGN: Cross-sectional prospective study. LOCATION: Community of Getafe (Madrid). Primary care level. PARTICIPANTS: 100 E. coli strains, randomly chosen, isolated from the urine (104-105cfu/ml) of different patients from primary care centers in the Getafe area. MAIN MEASUREMENTS: The antibiotic susceptibility of the strains was evaluated and the results were stratified by age and type of UTI. The clinical and demographic data of the patients were analyzed, classifying each episode as complicated UTI or uncomplicated UTI. RESULTS: Strains isolated from patients with uncomplicated UTI showed significantly greater susceptibility than those of complicated UTI to amoxicillin (65.9% vs. 30.6%, p=0.001), amoxicillin/clavulanic acid (95.5% vs. 77.6%, p=0.013) and ciprofloxacin (81.8% vs. 63.3%, p=0.047). In complicated UTI, susceptibility to ciprofloxacin was significantly greater in the ≤65 years age group compared to the older age group (78.3% vs. 50%, respectively, p=0.041). In the rest of antibiotics, no statistically significant differences were obtained when comparing by age (≤65 years versus >65 years), both in uncomplicated and complicated UTI. CONCLUSIONS: Clinical and demographic data of patients with UTI are of great importance in the results of the antibiotic susceptibility in E. coli. Antibiograms stratified by patient characteristics may better facilitate empirical antibiotic selection for UTI in primary care.

Enteropathogens and antibiotics. / Enteropatógenos y antibióticos.

Infectious gastroenteritis remains a public health problem. The most severe cases are of bacterial origin. In Spain, Campylobacter and Salmonella are the most prevalent bacterial genus, while Yersinia and Shigella are much less frequent. Most cases are usually self-limiting and antibiotic therapy is not generally indicated, unless patients have risk factors for severe infection and shigellosis. Ciprofloxacin, third generation cephalosporins, azithromycin, ampicillin, cotrimoxazole and doxycycline are the most recommended drugs. The susceptibility pattern of the different bacteria determines the choice of the most appropriate treatment. The aim of this review is to analyse the current situation, developments, and evolution of resistance and multidrug resistance in these 4 enteric pathogens.

Mycoplasma genitalium in Spain: prevalence of genital infection and frequency of resistance to macrolides.

INTRODUCTION: The aim of this study was to determine the prevalence of Mycoplasma genitalium infection and the resistance to macrolides within a general population in Madrid in 2015. METHODS: We collected 359 urine samples from a general population with symptoms of sexually transmitted infections (STIs). All samples underwent a real-time PCR. For the detection of macrolide resistance, a 283bp fragment of region V of the 23S rRNA gene of M. genitalium was amplified and sequenced. RESULTS: We found a prevalence of 3.34% of M. genitalium and a macrolide resistance rate of 20%. In males, the prevalence was 6.62% and in women 0.96%, being significantly higher in males. CONCLUSIONS: The prevalence obtained shows that it is a pathogen to consider in our environment. These findings stress the need for routine testing of M. genitalium infections and would seem to suggest the advisability of resistance testing.

Evolution of antibiotic multiresistance in Escherichia coli and Klebsiella pneumoniae isolates from urinary tract infections: A 12-year analysis (2003-2014).

INTRODUCTION: The aim of this study was to identify multi-drug resistance (MDR) in the main enterobacteriaceae implicated in urinary tract infections (Escherichia coli and Klebsiella pneumoniae) from both, community and hospitalized patients and to analyze the evolution over a 12-year period. METHODS: Microb Dynamic software was used to analyze the microbiology laboratory database and a chi square test was applied to compare differences in group proportions and to determine the linear trend over 12 years in three different periods: 2003-2006, 2007-2010, 2011-2014. We chose amoxicillin, gentamicin, ciprofloxacin and trimethoprim-sulphamethoxazole as MDR markers. RESULTS: A total of 39,980 positive urine samples were analyzed, 34,564 (3786 from hospitalized patients and 30,778 from non-hospitalized patients) E. coli isolates, and 5,422 (774 from hospitalized patients and 4,648 from non-hospitalized patients) K. pneumoniae isolates. The prevalence of UTI due to MDR E. coli and MDR K. pneumoniae significantly increased in the period studied, both in hospitalized and outpatients. A higher percentage of MDR E. coli (5.89% in 2007-2010 versus 8.18% in 2011-2014) and MDR K. pneumoniae (2.38% in 2007-2010 versus 9.35% in 2011-2014) was evident and maintained constant over time in hospitalized patients in comparison to non-hospitalized ones. Infection due to MDR ESBL-producing E. coli and K. pneumoniae increased significantly during the last 8 years in both, hospitalized (20% versus 38% and 66.8% versus 82.6%, respectively) and non-hospitalized patients (18.2% versus 23.6% and 51% versus 74.6%, respectively). CONCLUSIONS: This study includes data of a large sample size of urinary strains isolated over a 12 year period and demonstrates that MDR is an increasing phenomenon of particular importance in the main UTI-causing species.

Executive summary of the diagnosis and treatment of urinary tract infection: Guidelines of the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC).

Most urinary tract infections (UTI) are uncomplicated infections occurring in young women. An extensive evaluation is not required in the majority of cases, and they can be safely managed as outpatients with oral antibiotics. Escherichia coli is by far the most common uropathogen, accounting for >80% of all cases. Other major clinical problems associated with UTI include asymptomatic bacteriuria, and patients with complicated UTI. Complicated UTIs are a heterogeneous group associated with conditions that increase the risk of acquiring infection or treatment failure. Distinguishing between complicated and uncomplicated UTI is important, as it influences the initial evaluation, choice, and duration of antimicrobial therapy. Diagnosis is especially challenging in the elderly and in patients with in-dwelling catheters. The increasing prevalence of resistant uropathogens, including extended-spectrum ß-lactamases and carbapenemase-producing Enterobacteriaceae, and other multidrug-resistant Gram-negative organisms further compromises treatment of both complicated and uncomplicated UTIs. The aim of these Clinical Guidelines is to provide a set of recommendations for improving the diagnosis and treatment of UTI.

Survey of Carbapenemase-Producing Enterobacteriaceae in Companion Dogs in Madrid, Spain.

We found a low prevalence (0.6%) of carbapenemase-producingEnterobacteriaceae(CPE) in fecal microbiota of companion dogs. A single VIM-1-producingKlebsiella pneumoniaeisolate belonging to sequence type (ST) 2090 was detected.blaVIM-1was carried on a class 1 integron and an untypeable ∼48-kb plasmid. Emergence and spread of CPE in this group of animals may be a threat to public health in human and veterinary medicine. This finding supports the need for active surveillance studies in companion animals that live close to humans, as interspecies transmission may occur within the same household.

[Recommendations for management of acute pharyngitis in adults]. / Recomendaciones para el manejo de la faringoamigdalitis aguda del adulto.

Acute pharyngitis in adults is one of the most common infectious diseases seen in general practitioners' consultations. Viral aetiology is the most common. Among bacterial causes, the main agent is Streptococcus pyogenes or group A ß-haemolytic streptococcus (GABHS), which causes 5%-30% of the episodes. In the diagnostic process, clinical assessment scales can help clinicians to better predict suspected bacterial aetiology by selecting patients who should undergo a rapid antigen detection test. If these techniques are not performed, an overdiagnosis of streptococcal pharyngitis often occurs, resulting in unnecessary prescriptions of antibiotics, most of which are broad spectrum. Consequently, management algorithms that include the use of predictive clinical rules and rapid tests have been set up. The aim of the treatment is speeding up symptom resolution, reducing the contagious time span and preventing local suppurative and non-suppurative complications. Penicillin and amoxicillin are the antibiotics of choice for the treatment of pharyngitis. The association of amoxicillin and clavulanate is not indicated as the initial treatment of acute infection. Neither are macrolides indicated as first-line therapy; they should be reserved for patients allergic to penicillin. The appropriate diagnosis of bacterial pharyngitis and proper use of antibiotics based on the scientific evidence available are crucial. Using management algorithms can be helpful in identifying and screening the cases that do not require antibiotic therapy.

[Recommendations for management of acute pharyngitis in adults]. / Recomendaciones para el manejo de la faringoamigdalitis aguda del adulto.

Acute pharyngitis in adults is one of the most common infectious diseases seen in general practitioners' consultations. Viral aetiology is the most common. Among bacterial causes, the main agent is Streptococcus pyogenes or group A ß-haemolytic streptococcus (GABHS), which causes 5%-30% of the episodes. In the diagnostic process, clinical assessment scales can help clinicians to better predict suspected bacterial aetiology by selecting patients who should undergo a rapid antigen detection test. If these techniques are not performed, an overdiagnosis of streptococcal pharyngitis often occurs, resulting in unnecessary prescriptions of antibiotics, most of which are broad spectrum. Consequently, management algorithms that include the use of predictive clinical rules and rapid tests have been set up. The aim of the treatment is speeding up symptom resolution, reducing the contagious time span and preventing local suppurative and non-suppurative complications. Penicillin and amoxicillin are the antibiotics of choice for the treatment of pharyngitis. The association of amoxicillin and clavulanate is not indicated as the initial treatment of acute infection. Neither are macrolides indicated as first-line therapy; they should be reserved for patients allergic to penicillin. The appropriate diagnosis of bacterial pharyngitis and proper use of antibiotics based on the scientific evidence available are crucial. Using management algorithms can be helpful in identifying and screening the cases that do not require antibiotic therapy.

[Recommendations for management of acute pharyngitis in adults]. / Recomendaciones para el manejo de la faringoamigdalitis aguda del adulto.

Acute pharyngitis in adults is one of the most common infectious diseases seen in general practitioners' consultations. Viral aetiology is the most common. Among bacterial causes, the main agent is Streptococcus pyogenes or group A ß-haemolytic streptococcus (GABHS), which causes 5%-30% of the episodes. In the diagnostic process, clinical assessment scales can help clinicians to better predict suspected bacterial aetiology by selecting patients who should undergo a rapid antigen detection test. If these techniques are not performed, an overdiagnosis of streptococcal pharyngitis often occurs, resulting in unnecessary prescriptions of antibiotics, most of which are broad spectrum. Consequently, management algorithms that include the use of predictive clinical rules and rapid tests have been set up. The aim of the treatment is speeding up symptom resolution, reducing the contagious time span and preventing local suppurative and non-suppurative complications. Penicillin and amoxicillin are the antibiotics of choice for the treatment of pharyngitis. The association of amoxicillin and clavulanate is not indicated as the initial treatment of acute infection. Neither are macrolides indicated as first-line therapy; they should be reserved for patients allergic to penicillin. The appropriate diagnosis of bacterial pharyngitis and proper use of antibiotics based on the scientific evidence available are crucial. Using management algorithms can be helpful in identifying and screening the cases that do not require antibiotic therapy.