Activity of cefiderocol against high-risk clones of multidrug-resistant Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa and Stenotrophomonas maltophilia.

BACKGROUND: Cefiderocol is a novel siderophore cephalosporin, developed for activity against MDR Gram-negative bacilli (MDR-GNB). OBJECTIVES: To assess the in vitro antibacterial activity of cefiderocol against a collection of MDR-GNB clinical isolates from hospitals in southern Spain. METHODS: Two hundred and thirty-one isolates of successful clones were tested: 125 Enterobacterales (121 ESBL- and/or carbapenemase-producing Klebsiella pneumoniae and 4 carbapenemase-producing Enterobacter cloacae), 80 Acinetobacter baumannii, 6 Pseudomonas aeruginosa and 20 Stenotrophomonas maltophilia. Ceftolozane/tazobactam, ceftazidime, ceftazidime/avibactam, cefepime, aztreonam, meropenem, amikacin, ciprofloxacin, colistin and tigecycline were used as comparators against Enterobacterales, P. aeruginosa and A. baumannii. Minocycline, levofloxacin and trimethoprim/sulfamethoxazole were studied against S. maltophilia instead of aztreonam, ciprofloxacin and cefepime. MICs were determined by broth microdilution according to CLSI guidelines. MIC determination was performed in CAMHB for all antimicrobials except cefiderocol, where iron-depleted CAMHB was used. RESULTS: Cefiderocol showed potent in vitro activity against the isolates analysed. MIC50 and MIC90 values were in the ranges 0.125-8 mg/L and 0.5-8 mg/L, respectively, and 98% of isolates were inhibited at ≤4 mg/L. Only five isolates showed cefiderocol MICs of >4 mg/L: three ST2/OXA-24/40-producing A. baumannii, one ST114/VIM-1-producing E. cloacae and one ST114/VIM-1 + OXA-48-producing E. cloacae. All KPC-3-producing K. pneumoniae were susceptible to cefiderocol, even those resistant to ceftazidime/avibactam. P. aeruginosa isolates showed cefiderocol MICs of <4 mg/L, including those resistant to ceftolozane/tazobactam. S. maltophilia isolates displayed cefiderocol MICs of <4 mg/L, including those resistant to levofloxacin and/or trimethoprim/sulfamethoxazole. CONCLUSIONS: Cefiderocol showed excellent activity against MDR-GNB, including carbapenem-resistant isolates, and was the most active antimicrobial tested against this collection.

Extended-spectrum ß-lactamase-producing Enterobacteriaceae from animal origin and wastewater in Tunisia: first detection of O25b-B23-CTX-M-27-ST131 Escherichia coli and CTX-M-15/OXA-204-producing Citrobacter freundii from wastewater.

OBJECTIVES: This study aimed to isolate and characterise extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) isolates from animals and wastewater in Tunisia. METHODS: ESBL-E from wastewater (n=123 samples), faeces of healthy animals (poultry, sheep, goats and calves) (n=140) and raw milk from healthy cows (n=42) and goats (n=20) were investigated. Antimicrobial susceptibility was determined according to CLSI recommendations. The blaTEM, blaSHV, blaCTX-M and blaOXA-48 genes were analysed by PCR and sequencing. Phylogenetic groups were determined by PCR for Escherichia coli isolates. The clonality of E. coli and Klebsiella pneumoniae isolates was determined by XbaI-PFGE and MLST. RESULTS: A total of 81 E. coli, 20 K. pneumoniae, 4 Enterobacter cloacae, 1 Citrobacter freundii and 1 Citrobacter braakii were isolated. The blaCTX-M-1 and blaCTX-M-15 genes were predominant in E. coli and K. pneumoniae isolates. E. cloacae and C. braakii isolates harboured the blaSHV-12 gene. The C. freundii isolated from wastewater carried blaCTX-M-15, blaTEM-1 and blaOXA-204. E. coli isolates belonged to phylogroups A (37), B1 (25), B2 (7) and D (12). Seventy-eight E. coli isolates were typeable by PFGE and were classified into 34 pulsotypes. The K. pneumoniae isolates belonged to 11 pulsotypes. The E. coli isolates belonged to sequence types ST131, ST224, ST162, ST845, ST5204, ST69, ST141 and ST10. The K. pneumoniae isolates belonged to ST405, ST147, ST564, ST307, ST152, ST45, ST661 and ST1564. CONCLUSION: This is the first report of O25b-B23-CTX-M-27-ST131 E. coli isolates and of C. freundii carrying blaCTX-M-15, blaTEM-1 and blaOXA-204 in Tunisia.

Duration of Colonization by Extended-Spectrum ß-Lactamase-Producing Enterobacteriaceae in Healthy Newborns and Associated Risk Factors: A Prospective Cohort Study.

Duration of colonization by extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) and factors associated with it were studied in 20 newborns in Seville, Spain. Median duration of colonization was 7.5 months; factors associated with prolonged colonization were delivery by caesarean section, colonization of the mother, and phylogroup B2 Eschericha coli isolate.

Incidence and Risk Factors for Acquisition of Extended-Spectrum ß-Lactamase-Producing Enterobacteriaceae in Newborns in Seville, Spain: A Prospective Cohort Study.

BACKGROUND: ESBL-producing Enterobacteriaceae (ESBL-E) are an emerging cause of infections in children. Data are scarce on incidence rates and risk factors for acquisition of colonisation with ESBL-E. METHODS: A total of 46 and 50 newborns from colonised and non-colonised mothers, respectively, were followed during one year after birth. Rectal swabs were performed every 3 months to detect ESBL-E; blaESBL were characterised and isolates were typed for comparison. Multivariate analysis for risk factors was performed using Cox regression. RESULTS: Incidence density of any new acquisition and of first acquisition of ESBL-E was 2.7 and 1.9 episodes per 100 children-month, respectively, among children whose mothers were colonised, and 1.2 and 1.3, respectively, among children whose mothers were not. The weighted average prevalence of colonisation rates during the first year were 15.9% and 8%, respectively. No infections due to ESBL-E were detected. Living with pets at home, breastfeeding, sterilisation of feeding bottles and out-of-home childcare were protective for ESBL-E acquisition; having a colonised mother increased the risk. The most frequent ESBL types were CTX-M-14 and CTX-M-1. In 5/19 (26.3%) children with acquisition of new clones, the acquired ESBL-E was shared with their mothers. CONCLUSIONS: Acquisition of ESBL-E colonisation is not rare during the first year of life. Breastfeeding and out-of-home childcare were protective for acquisition, and colonised mothers were associated with increased risk. However, the same clone was shared by mother and child in only a subset of acquisition episodes.

Bacteraemia due to non-ESBL-producing Escherichia coli O25b:H4 sequence type 131: insights into risk factors, clinical features and outcomes.

The epidemiology and outcomes of bloodstream infections (BSIs) caused by Escherichia coli ST131 isolates not producing extended-spectrum ß-lactamases (ESBLs) are not well defined despite being more prevalent than ESBL-producers. In this study, risk factors and the impact on outcome of BSIs caused by non-ESBL-producing ST131 E. coli versus non-ST131 E. coli were investigated. A case-control study was performed in two tertiary centres to identify risk factors for ST131. Molecular methods were used to investigate all E. coli isolates from blood cultures for those belonging to O25b:H4-ST131 clonal group. fimH alleles were characterised in ST131 isolates. Multivariate analysis was performed by logistic regression or Cox regression as appropriate. A total of 33 ST131 E. coli cases and 56 controls were studied. ST131 isolates showed higher rates of resistance to ampicillin and ciprofloxacin; fimH alleles were H30 in 14 isolates (42.4%) and H22 in 12 isolates (36.4%). Only recent surgery (OR = 7.03, 95% CI 1.71-28.84; P = 0.007) and unknown source of bacteraemia (OR = 5.37, 95% CI 0.93-30.81; P = 0.05) were associated with ST131. ST131 isolates showed no association with 30-day mortality, therapeutic failure, presentation with severe sepsis/shock or length of stay. Bacteraemia due to non-ESBL-producing O25b:H4-ST131 E. coli showed few differences in terms of risk factors as well as similar outcome to non-ST131 E. coli. These data support the notion that ST131 strains are not less clinically virulent despite showing increased antimicrobial resistance, but also that they are not more virulent than other clonal groups causing BSI.

Escherichia coli O25b: H4/ST131 es prevalente en España y con frecuencia no se encuentra asociado a resistencia a quinolonas o producción de beta-lactamasas de espectro ampliado (BLEE) / No disponible

Introducción Recientemente, y de forma simultánea en 3 continentes, ha emergido un grupo clonal de E. coli multirresistente y productor de CTX-M-15. Por el momento, se dispone de pocos estudios que analicen de forma apropiada la prevalencia real de este linaje. Métodos En un estudio prospectivo en el sur de España, realizado con todos los aislados clínicos de E. coli recuperados en Sevilla durante 30 semanas en 2010, se realizó el despistaje de ST131 mediante PCR para O25b/pabB3/B23. Los enzimas BLEE fueron caracterizados mediante PCR y posterior secuenciación. La relación genética de los aislados fue estudiada mediante PFGE con XbaI. Resultados la prevalencia de este grupo clonal resultó ser del 12,5% de todos los aislados de E. coli y únicamente 37 (6,8% de los aislados ST131) eran productores de BLEE. Se caracterizaron 25 aislados ST131 productores de BLEE y la mayoría (96%) producían CTX-M-15. Los aislados ST131 eran con más frecuencia resistentes a amoxicilina/clavulánico, aminoglicósidos y fluorquinolonas tanto en el grupo de productores de BLEE como en el de no productores. En el análisis mediante XbaI PFGE, realizado a 88 aislados ST131, se observaron 3 pulsotipos, que incluían ≥4 aislados cada uno (25% de todos los aislados ST131 tipados) y 11 pulsotipos, que contenían 2-3 aislados cada uno. Tres de los 14 pulsotipos de este grupo clonal incluían aislados sensibles y resistentes al ácido nalidíxico y 5 pulsotipos incluían productores y no productores de BLEE. Conclusiones Los hallazgos de este estudio sugieren que O25b/ST131 es un clon prevalente en nuestra área y la prevalencia de BLEE en el referido clon es idéntica a la que se encuentra en la totalidad de los aislados de la especie. Algunos pulsotipos dentro del clon muestran una expansión mayor que podría ser explicada en parte por la adquisición de genes codificantes de BLEEs o resistencia a quinolonas (AU)

Introduction A multiresistant CTX-M-15-producing clonal group of Escherichia coli isolates, namely O25b:H4/ST131, has recently emerged in three continents. At this moment, appropriate studies to assess the real prevalence of this successful lineage are still scarce. Methods In a prospective study in the south of Spain, among all clinical E. coli isolates recovered in Seville during a 30 week period in 2010, ST131 was screened by using PCR for O25b/pabB3/B23 traits. ESBL enzymes were characterized by PCR and sequencing. Genetic relatedness was performed by XbaI PFGE. Results This clonal group was found to be prevalent (12.5% of all E. coli isolates), and only 37 (6.8% of ST131 isolates) were ESBL producers. Among 25 characterized ESBL-producing ST131 isolates, 96% harbored CTX-M-15. ST131 isolates were more frequently resistant to amoxicillin/clavulanate, aminoglycosides and fluoroquinolones in both ESBL and non-ESBL producers groups. XbaI PFGE performed on 88 ST131 isolates showed three pulsotypes, which included ≥4 isolates each (25% of all typed ST131 isolates), and 11 pulsotypes, which contained 2–3 isolates each. Three of 14 pulsotypes of this clonal group included both nalidixic acid-resistant and susceptible isolates, and five pulsotypes included both ESBL and non-ESBL producers. Conclusions Our findings suggest that O25b/ST131 is a prevalent clone in our area, and the observed prevalence of ESBL-producers within this clone is similar to that found in the total isolates of this species. Certain pulsotypes among ST131 clone that showed a greater expansion, and ESBL genes acquisition or quinolone resistance could explain part of this prevalence (AU)

Outcome of bacteraemia due to extended-spectrum ß-lactamase-producing Escherichia coli: impact of microbiological determinants.

OBJECTIVES: To investigate the impact of virulence factors (VF) and other microbiological determinants on the outcome of patients with invasive infections due to extended-spectrum ß-lactamase-producing Escherichia coli (ESBLEC). METHODS: A prospective multicentre cohort including 191 patients with bacteraemia due to ESBLEC from 13 hospitals in Spain was studied. Phylogroups and 25 genes encoding for putative VF were studied by PCR. Main outcome variable was 30-day mortality; presentation with severe sepsis or septic shock was also assessed. Logistic regression was used to performed multivariate analyses. RESULTS: After controlling for patient comorbidity, source, and empirical antimicrobial therapy, ibeA (OR = 3.41; 95% CI: 0.96-12.10) and amoxicillin-clavulanate resistance (OR = 2.38; 95% CI: 1.07-5.26) were independently associated with increased mortality, while papGII showed a protective effect (OR = 0.18; 95% CI: 0.04-0.87). When these 3 variables were deleted from the multivariate model, the area under the ROC curve decreased only from 0.83 to 0.77. papGII also showed a protective effect for presentation with severe sepsis or septic shock (adjusted OR = 0.34; 95% CI: 0.10-1.14). CONCLUSION: Some pathogen-associated determinants showed a significant although limited impact on outcome in bacteraemic infections due to ESBLEC, and should be further studied as potential therapeutic or preventive targets.

Escherichia coli O25b:H4/ST131 are prevalent in Spain and are often not associated with ESBL or quinolone resistance.

INTRODUCTION: A multiresistant CTX-M-15-producing clonal group of Escherichia coli isolates, namely O25b:H4/ST131, has recently emerged in three continents. At this moment, appropriate studies to assess the real prevalence of this successful lineage are still scarce. METHODS: In a prospective study in the south of Spain, among all clinical E. coli isolates recovered in Seville during a 30 week period in 2010, ST131 was screened by using PCR for O25b/pabB3/B23 traits. ESBL enzymes were characterized by PCR and sequencing. Genetic relatedness was performed by XbaI PFGE. RESULTS: This clonal group was found to be prevalent (12.5% of all E. coli isolates), and only 37 (6.8% of ST131 isolates) were ESBL producers. Among 25 characterized ESBL-producing ST131 isolates, 96% harbored CTX-M-15. ST131 isolates were more frequently resistant to amoxicillin/clavulanate, aminoglycosides and fluoroquinolones in both ESBL and non-ESBL producers groups. XbaI PFGE performed on 88 ST131 isolates showed three pulsotypes, which included ≥4 isolates each (25% of all typed ST131 isolates), and 11 pulsotypes, which contained 2-3 isolates each. Three of 14 pulsotypes of this clonal group included both nalidixic acid-resistant and susceptible isolates, and five pulsotypes included both ESBL and non-ESBL producers. CONCLUSIONS: Our findings suggest that O25b/ST131 is a prevalent clone in our area, and the observed prevalence of ESBL-producers within this clone is similar to that found in the total isolates of this species. Certain pulsotypes among ST131 clone that showed a greater expansion, and ESBL genes acquisition or quinolone resistance could explain part of this prevalence.

Increased raw poultry meat colonization by extended spectrum beta-lactamase-producing Escherichia coli in the south of Spain.

The present study was conducted to assess the prevalence of retail chicken and turkey meat colonized by extended-spectrum beta-lactamase-producing Escherichia coli (ESBLEC) in Seville, Spain. ESBLEC recovered from meat samples purchased in 2010 were characterized by specific PCR analysis for bla genes, phylogenetic groups and subgroups (genotypes) and O25b/pabB/B2 traits of ST131. Results were compared with those obtained in a previous study in 2007, when a high percentage of retail meat samples were found to be colonized by ESBLEC. The prevalence of retail poultry meat colonized by ESBLEC increased from 62.5% in 2007 to 93.3% in 2010 (p=0.005). Non-pathogenic B1 and A(1) genotypes accounted for more than 60% of the 60 isolates recovered. Sequence type ST131 or B2 phylogroup isolates were not detected. Clonal relatedness was detected in just 2 CTX-M-1-producing isolates from 2 chicken samples belonging to phylogenetic group A, genotype A(1). There continued to be a significantly high quinolone resistance, with 85.4% and 32.2% of isolates showing resistance to nalidixic acid and ciprofloxacin, respectively. SHV-12 was the most common ESBL harbored by E. coli, although it has decreased in prevalence since 2007. Meanwhile, CTX-M ESBLs prevalence has increased. We conclude that the trend of colonization by ESBLECs-particularly CTX-M-producing isolates-in raw poultry meat has increased in a short period of time in our area.

Virulence profiles of bacteremic extended-spectrum ß-lactamase-producing Escherichia coli: association with epidemiological and clinical features.

There is scarce data about the importance of phylogroups and virulence factors (VF) in bloodstream infections (BSI) caused by extended-spectrum ß-lactamase-producing Escherichia coli (ESBLEC). A prospective multicenter Spanish cohort including 191 cases of BSI due to ESBLEC was studied. Phylogroups and 25 VF genes were investigated by PCR. ESBLEC were classified into clusters according to their virulence profiles. The association of phylogropus, VF, and clusters with epidemiological features were studied using multivariate analysis. Overall, 57.6%, 26.7%, and 15.7% of isolates belonged to A/B1, D and B2 phylogroups, respectively. By multivariate analysis (adjusted OR [95% CI]), virulence cluster C2 was independently associated with urinary tract source (5.05 [0.96-25.48]); cluster C4 with sources other than urinary of biliary tract (2.89 [1.05-7.93]), and cluster C5 with BSI in non-predisposed patients (2.80 [0.99-7.93]). Isolates producing CTX-M-9 group ESBLs and from phylogroup D predominated among cluster C2 and C5, while CTX-M-1 group of ESBL and phylogroup B2 predominantes among C4 isolates. These results suggest that host factors and previous antimicrobial use were more important than phylogroup or specific VF in the occurrence of BSI due to ESBLEC. However, some associations between virulence clusters and some specific epidemiological features were found.

Characterisation of clinical and food animal Escherichia coli isolates producing CTX-M-15 extended-spectrum ß-lactamase belonging to ST410 phylogroup A.

Seven phylogroup A CTX-M-15-producing Escherichia coli isolates recovered from clinical and meat samples were further characterised. All of them belonged to sequence type ST410. Only 2 of the 22 virulence genes investigated were detected. All isolates carried the fimH gene encoding type 1 fimbriae, and five isolates harboured the iucD gene encoding aerobactin siderophore. A group of five isolates showed 81.2% similarity by pulsed-field gel electrophoresis (PFGE), comprising three clinical isolates belonging to ONT:H9 and two food isolates belonging to O55:H9. Different HpaI digestion patterns were observed for plasmids, but all of them belonged to IncFIB group and harboured bla(CTX-M-15) associated with bla(OXA-1), bla(TEM), tetA, catB3 and aac(6')-Ib surrounded by an identical genetic environment. These findings showed the possibility of lateral gene transfer of bla(CTX-M-15) as well as other antibiotic resistance determinants between low-virulence food and clinical isolates.