Intestinal colonization due to Escherichia coli ST131: Risk factors and prevalence

Background Escherichia coli sequence type 131 (ST131) is a successful clonal group that has dramatically spread during the last decades and is considered an important driver for the rapid increase of quinolone resistance in E. coli. Methods Risk factors for rectal colonization by ST131 Escherichia coli (irrespective of ESBL production) were investigated in 64 household members (18 were colonized) and 54 hospital contacts (HC; 10 colonized) of 34 and 30 index patients with community and nosocomial infection due to these organisms, respectively, using multilevel analysis with a p limit of < 0.1. Result Colonization among household members was associated with the use of proton-pump inhibitors (PPI) by the household member (OR = 3.08; 95% CI: 0.88–10.8) and higher age of index patients (OR = 1.05; 95% CI; 1.01–1.10), and among HC, with being bed-ridden (OR = 21.1; 95% CI: 3.61–160.0) and having a urinary catheter (OR = 8.4; 95% CI: 0.87–76.9). Conclusion Use of PPI and variables associated with higher need of person-to-person contact are associated with increased risk of rectal colonization by ST131. These results should be considered for infection control purposes.Plan Nacional de I + D + i 2013-2016Ministerio de Economía y Competitividad (España)European Development Regional Fund REIPI RD12/0015/0010 REIPI RD16/0016/0001Instituto de Salud Carlos III 070190 AC16/000076-MODERN AC16/AC16/00072-ST131TSJunta de Andalucía CTS5259 CTS21

Penicillin susceptibility among invasive MSSA infections: a multicentre study in 16 Spanish hospitals

Objectives: To determine the prevalence of penicillin susceptibility among MSSA causing bloodstream infections (BSIs) in 16 Spanish hospitals and to characterize the penicillin-susceptible MSSA (MSSA-PENS) isolates. Methods: A total of 1011 Staphylococcus aureus isolates were collected from blood cultures in 16 Spanish hospitals during 2018–19 (6–12 months) and their susceptibility to 18 antimicrobials was determined. The MSSA-PENS isolates were selected and examined by PCR to determine the presence of the blaZ gene, other resistance genes and the genes lukF/lukS-PV, eta, etb and tst. The immune evasion cluster (IEC) type was also analysed. All the MSSA-PENS isolates were submitted to S. aureus protein A (spa) typing and the clonal complexes (CCs) were assigned according to their spa type. Results: The prevalence of MSSA was 74.6% (754/1011) and 14.9% (151/1011) were MSSA-PENS-blaZnegative. MSSA-PENS-blaZnegative isolates (n = 151) were ascribed to 88 spa types and 11 CCs. The most frequent CCs were CC5 (35/151) and CC398 (25/151), with t002-CC5 and t571-CC398 being the most common lineages. Pan-susceptibility was identified in 117 of the 151 MSSA-PENS-blaZnegative isolates (77.5%). In the remaining isolates, erythromycin and clindamycin resistance was the most frequent resistance found, although tobramycin, ciprofloxacin, fusidic acid, mupirocin and/or tetracycline resistance was also detected. Thirty-eight MSSA-PENS-blaZnegative isolates were IEC negative and four isolates were Panton–Valentine leucocidin (‘PVL’) positive. Conclusions: A high penicillin susceptibility rate was detected among MSSA, opening therapeutic opportunities for BSIs. The emergence of new successful MSSA-PENS clones could be responsible for these data. The detection among MSSA-PENS-blaZnegative isolates of the clonal lineage CC398 or the absence of an IEC raises questions about their possible animal origin, requiring further analysis

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

Prevalence and genetic characteristics of Staphylococcus aureus CC398 isolates from invasive infections in spanish hospitals, focusing on the livestock-independent CC398-MSSA clade

Background: Livestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported. Objectives: To determine the prevalence of Staphylococcus aureus (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates. Methods: One thousand twenty-two SA isolates (761 MSSA, 261 MRSA) recovered from blood cultures during 6–12 months in 17 Spanish hospitals (2018–2019) were studied. CC398 lineage identification, detection of spa-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing. Results: Forty-four CC398-MSSA isolates (4.3% of SA; 5.8% of MSSA) and 10 CC398-MRSA isolates (1% of SA; 3.8% of MRSA) were detected. Eleven spa-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent spa-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin–inducible-resistant/erm(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km2) (p = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately spa-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (p < 0.005). Conclusion: CC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers.

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

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

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. 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. 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 β-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 β-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). 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

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

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