Prevalence and risks factors associated with ESBL-producing faecal carriage in a single long-term-care facility in Spain: emergence of CTX-M-24- and CTX-M-27-producing Escherichia coli ST131-H30R.

OBJECTIVES: To address the faecal carriage prevalence of antibiotic-multiresistant bacteria and associated risk factors in a public long-term care facility (LTCF). METHODS: A prospective study in a single government-funded LTCF of 300 residents in Ciudad Real, Spain. Residents' clinical and demographic data were collected, as well as recent antibiotic consumption in the institution. Each participant contributed a rectal swab, which was plated on selective and differential-selective media. Colonies were identified by MALDI-TOF and ESBL production was confirmed by the double-disc synergy method, with characterization of the molecular mechanism by PCR. Isolates were typed by PFGE and submitted for ST131 screening by PCR. RESULTS: Faecal carriage of ESBL-producing Enterobacterales was detected in 58 (31%) of 187 participants and previous infection by MDR bacteria was identified as a risk factor. The genes characterized were: blaCTX-M-15 (40.6%); blaCTX-M-14 (28.8%); blaCTX-M-27 (13.5%); and blaCTX-M-24 (10.1%). Some 56.4% of the isolates were grouped into the E. coli ST131 clone; 70.9% of these corresponded to the O25b serotype, 51.6% of them to Clade C1 (H30) and 12.9% to Clade C2 (H30Rx). Clade C1 isolates were mostly C1-M27, whereas the C2 sublineage was mainly related to the production of CTX-M-15. ST131-CTX-M-24 isolates (n = 6) corresponded to Clade A with serotype O16. CONCLUSIONS: A high prevalence of ESBL-producing Enterobacterales faecal carriage has been detected in a single LTCF, highlighting the emergence of ST131 Clade A-M24 and Clade C1-M27 lineages.

Global study of IS6110 in a successful Mycobacterium tuberculosis strain: clues for deciphering its behavior and for its rapid detection.

The Mycobacterium tuberculosis insertion sequence IS6110, besides being a very useful tool in molecular epidemiology, seems to have an impact on the biology of bacilli. In the present work, we mapped the 12 points of insertion of IS6110 in the genome of a successful strain named M. tuberculosis Zaragoza (which has been referred to as the MTZ strain). This strain, belonging to principal genetic group 3, caused a large unsuspected tuberculosis outbreak involving 85 patients in Zaragoza, Spain, in 2001 to 2004. The mapping of the points of insertion of IS6110 in the genome of the Zaragoza strain offers clues for a better understanding of the adaptability and virulence of M. tuberculosis. Surprisingly, the presence of one copy of IS6110 was found in Rv2286c, as was recently described for a successful Beijing sublineage. As a result of this analysis, a rapid method for detecting this particular M. tuberculosis strain has been designed.

Production of the Invasive Aspergillosis Biomarker Bis(methylthio)gliotoxin Within the Genus Aspergillus: In Vitro and in Vivo Metabolite Quantification and Genomic Analysis.

Gliotoxin (GT) is a fungal secondary metabolite that has attracted great interest due to its high biological activity since it was discovered by the 1930s. An inactive derivative of this molecule, bis(methylthio)gliotoxin (bmGT), has been proposed as an invasive aspergillosis (IA) biomarker. Nevertheless, studies regarding bmGT production among common opportunistic fungi, including the Aspergillus genus, are scarce and sometimes discordant. As previously reported, bmGT is produced from GT by a methyl-transferase, named as GtmA, as a negative feedback regulatory system of GT production. In order to analyze the potential of bmGT detection to enable identification of infections caused by different members of the Aspergillus genus we have assessed bmGT production within the genus Aspergillus, including A, fumigatus, A. niger, A. nidulans, and A. flavus, and its correlation with gtmA presence. In order to validate the relevance of our in vitro findings, we compared bmGT during in vitro culture with the presence of bmGT in sera of patients from whom the Aspergillus spp. were isolated. Our results indicate that most A. fumigatus isolates produce GT and bmGT both in vitro and in vivo. In contrast, A. niger and A. nidulans were not able to produce GT or bmGT, although A. niger produced bmGT from a exogenous GT source. The frequency and amount of bmGT production in A. terreus and A. flavus isolates in vitro was lower than in A. fumigatus. Our results suggest that this defect could be related to the in vitro culture conditions, since isolates that did not produce bmGT in vitro were able to synthetize it in vivo. In summary, our study indicates that bmGT could be very useful to specifically detect the presence of A. fumigatus, the most prevalent agent causing IA. Concerning A. terreus and A. flavus a higher number of analyses from sera from infected patients will be required to reach a useful conclusion.

Bis(methyl)gliotoxin proves to be a more stable and reliable marker for invasive aspergillosis than gliotoxin and suitable for use in diagnosis.

The virulence factor gliotoxin (GT) and its inactive derivative, bis(methylthio)gliotoxin (bmGT), are produced by pathogens of the genus Aspergillus. Here we report the detection of GT and bmGT in serum of humans at risk of invasive aspergillosis (IA) as well as in cultures of fungal isolates derived from patients with proven infection with A. fumigatus. Although both compounds are readily recoverable from spiked human serum or plasma, only bmGT is retained in whole blood, indicating that bmGT may be the better marker for in vivo detection. Accordingly, bmGT was found more frequently than GT in samples from patients at risk of IA and incultures of clinical isolates of A. fumigatus. In some cases, bmGT was detected before mycologic evidence ofinfection was gained. Importantly, neither GT nor bmGT was found in serum from healthy donors or from neutropenic patients without any sign of infection. Thus, bmGT presence might provide a more reliable indicator of A. fumigatus infections than GT. Due to its simplicity and sensitivity, a diagnostic technology based on this test could be easily adopted in clinical laboratories to help in the diagnosis of this often fatal fungal infection.