Molecular epidemiology and clinical characteristics of Clostridioides difficile infection in patients with inflammatory bowel disease from a teaching hospital.

BACKGROUND: Clostridioides difficile infection (CDI) in patients with inflammatory bowel disease (IBD) is of increasing concern. This study aimed to investigate the molecular epidemiology and antimicrobial susceptibilities of toxigenic C. difficile isolated from IBD patients and to evaluate the risk factors for CDI in IBD population. METHODS: Loose or watery stools from IBD patients were tested for glutamate dehydrogenase, C. difficile toxins A&B and anaerobic culture. Toxigenic C. difficile isolates were characterized by multi-locus sequence typing, ribotyping and antimicrobial susceptibility testing. RESULTS: The prevalence of CDI in IBD patients was 13.6% (43/317). The dominant sequence types (STs) were ST35 (20.9%), ST2 (18.6%) and ST37 (16.3%). The most common ribotypes (RTs) were RT 017 (18.6%), RT 012 (14.0%), and RT 220 (14.0%), whereas RT 027 and RT 078 were not detected in this study. All the isolates were susceptible to vancomycin and metronidazole. The multidrug resistance rate of C. difficile RT 017 was higher (p < 0.01) than that of other RT strains. Recent hospitalization, use of corticosteroids and proton pump inhibitors were related to increased risk of CDI in IBD patients; of these, recent hospitalization and proton pump inhibitors use were independent risk factors. CONCLUSION: Patients with IBD have a relatively high incidence rate of CDI. C. difficile RT 017 is most frequently isolated from IBD patients in this region and warrants more attention to its high resistance rate. Clinicians should pay greater attention to CDI testing in IBD patients with diarrhea to ensure early diagnosis and initiation of effective treatment.

Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China.

OBJECTIVES: The objectives of this study were to determine CTX-M-producing Escherichia coli ST131 strain prevalence in stool specimens from healthy subjects in central China and to molecularly characterize clonal groups. METHODS: From November 2013 to January 2014, stool specimens from healthy individuals in Hunan Province were screened for ESBL-producing E. coli using chromogenic medium and CTX-M genotypes and phylogenetic groups were determined. ST131 clonal groups were detected by PCR and characterized for antibiotic resistance, fimH, gyrA and parC alleles, plasmid-mediated quinolone resistance determinants, virulence genotypes and PFGE patterns. RESULTS: Among 563 subjects, 287 (51.0%) exhibited the presence of faecal ESBL-producing E. coli, all of which produced CTX-M enzymes. The most common CTX-M genotypes were CTX-M-14 (48.4%), CTX-M-15 (27.5%) and CTX-M-27 (15.0%). Of the 287 CTX-M-producing isolates, 32 (11.1%) belonged to the ST131 clone. O16-ST131 isolates were dominant (75%) and contained the fimH41 allele. The remaining eight (25%) ST131 isolates were of the O25b subgroup and contained fimH30 or fimH41. Ciprofloxacin resistance was found in 100% of the O25b-ST131 isolates, whereas only 8% of the O16-ST131 isolates were resistant. All of the O25b-ST131 isolates except one showed gyrA1AB and parC1aAB mutations; most of the O16-ST131 isolates had gyrA1A and parC1b mutations. The virulence genotypes of O16-ST131 resembled those of the O25b-ST131 isolates. The 32 ST131 isolates formed one large group at the 64% similarity level. They comprised 15 PFGE groups (defined at ≥85% similarity). CONCLUSIONS: O16-ST131 isolates have emerged as the predominant type of ST131 isolate in faecal CTX-M-producing E. coli in healthy individuals in China.

Molecular epidemiology of Clostridium difficile infection in a major chinese hospital: an underrecognized problem in Asia?

Clostridium difficile infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of C. difficile, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for C. difficile retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom C. difficile was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of C. difficile were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified C. difficile as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital. C. difficile may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.

Community Fecal Carriage and Molecular Epidemiology of Extended-Spectrum ß-Lactamase- and Carbapenemase-Producing Escherichia coli from Healthy Children in the Central South China.

Background: Fecal carriage of extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) and carbapenemase-producing E. coli (CP-EC) is well reported among hospitalized adults and children. However, there are few studies on the carriage prevalence and ESBL-EC and CP-EC genotypes among healthy children in China. Patients and Methods: Stool samples were collected from 330 students in 2021 from three randomly selected primary schools in Changsha, China. ESBL-EC and CP-EC were screened using CHROMagarTM chromogenic plates. ESBL and carbapenemase production was confirmed using the double-disc synergy test and a modified carbapenem inactivation method, respectively. Antimicrobial susceptibility was tested using the broth microdilution method. Resistance determinants, virulence factors, and phylogenetic groups were determined by PCR and sequencing. Multi-locus sequence typing (MLST) was performed (seven housekeeping genes were amplified and sequenced) on the phylogenic group B2 E. coli to detect high-risk clonal strains such as ST131 E. coli. Then, ST131 E. coli were characterized based on ST131 clades, O-type, and fimH alleles. Results: In total, 118 (35.8%) ESBL-EC and 3 (0.9%) CP-EC were isolated. bla CTX-M was the most common genotype (27.1%), identified in all ESBL-EC, except one, which carried bla SHV-12. One isolate with mcr-1 was found amongst ESBL-EC, whereas all three CP-EC carried bla NDM-1. The predominant sequence type (ST) clones in group B2 were ST131 and ST1193. The prevalence of ST131 E. coli was 9.9%, displaying serotypes O16 and O25b, fimH alleles 30, 41, and 89, and ST131 clades A and C1-M27. Conclusion: In this study, high carriage rate of ESBL-EC was found among healthy children, and the dominant ESBL was CTX-M-14. In addition, high-risk clones (ST131 and ST1193) were also detected. This emphasizes the importance of monitoring ESBL-EC in community settings.

Evaluation of our self-designed nanometer silicon membrane sandwich cup system for diagnosing tuberculosis.

BACKGROUND AND AIMS: A nanometer silicon membrane sandwich cup system was self-designed. It could concentrate the bacilli via 0.45-µm microporous filter membrane and semi-automate the acid-fast bacilli (AFB) by a bacteria-staining machine. The aim of the study was to assess the clinical value of our self-designed system for diagnosing tuberculosis (TB). METHODS: A total of 1993 sputum specimens obtained from patients with confirmed or suspected TB were subjected to direct or concentrated specimens smear at XiangYa Hospital, Central South University between May 2012 and February 2013. In addition, all the specimens were also inoculated into Lowenstein-Jensen (L-J) media, and culture results were considered as the gold standard for calculating sensitivity and specificity. RESULTS: Compared with direct smear examination, an increased density of red stained bacilli was observed in the self-designed nanometer silicon membrane sandwich cup analysis under the microscope. The positive rate of the self-designed analysis was significantly higher than that of direct AFB smear [10.9% (217/1993) vs 6.2% (123/1993), P < 0.05]. The sensitivity of the self-designed system increased (97.3% vs 55.2%, P < 0.05) without a loss of specificity (100% vs 100%) for identifying positive TB cases compared with the direct smear method. CONCLUSION: The self-designed nanometer silicon membrane sandwich cup and semi-automatic bacteria-staining machine could more efficiently and rapidly detect the AFB in respiratory specimens than direct microscopy. This is a novel and safe examination, and it may replace direct smear examination for the diagnosis of patients with TB.