Analysis of biofilm production and expression of adhesion structures of circulating Clostridioides difficile strains from Mexico

INTRODUCTION

Clostridioides difficile biofilms are believed to protect the pathogen from antibiotics, in addition to potentially contributing to recurrent infections.

METHODOLOGY

Biofilm production of 102 C. difficile isolates was determined using the crystal violet staining technique, and detachment assays were performed. The expression levels of cwp84 and slpA genes were evaluated by real-time PCR on selected isolates.

RESULTS

More than 70% of isolates (75/102) were strong biofilm producers, and the highest detachment of biofilm was achieved with the proteinase K treatment (>90%). The overall mean expression of cwp84 was higher in RT027 than in RT001 (p=0.003); among strong biofilm-producing strains, the slpA expression was lower in RT027 than in RT001 (p<0.000).

CONCLUSIONS

Proteins seem to have an important role in the biofilm's initial adherence and maturation. slpA and cwp84 are differentially expressed by C. difficile ribotype and biofilm production level.

Diversity of Circulating Clostridioides difficile Ribotypes in Mexico and Susceptibility to Fidaxomicin, Vancomycin, and Metronidazole

In this study, we report the results of the epidemiological analysis of Clostridioides difficile ribotypes (RTs) and antimicrobial susceptibility testing. Most isolates were RT027, representing 73% (84/115) of isolates. No isolates with reduced susceptibility to fidaxomicin were found; however, 38 (33.04%) isolates had reduced susceptibility to metronidazole, and 7 isolates (6.1%) had reduced susceptibility to vancomycin. These findings highlight the need for continuous surveillance of C. difficile RTs and antimicrobial susceptibility testing.

Analysis of biofilm production and expression of adhesion structures of circulating Clostridioides difficile strains from Mexico

INTRODUCTION

Clostridioides difficile biofilms are believed to protect the pathogen from antibiotics, in addition to potentially contributing to recurrent infections.

METHODOLOGY

Biofilm production of 102 C. difficile isolates was determined using the crystal violet staining technique, and detachment assays were performed. The expression levels of cwp84 and slpA genes were evaluated by real-time PCR on selected isolates.

RESULTS

More than 70% of isolates (75/102) were strong biofilm producers, and the highest detachment of biofilm was achieved with the proteinase K treatment (>90%). The overall mean expression of cwp84 was higher in RT027 than in RT001 (p=0.003); among strong biofilm-producing strains, the slpA expression was lower in RT027 than in RT001 (p<0.000).

CONCLUSIONS

Proteins seem to have an important role in the biofilm's initial adherence and maturation. slpA and cwp84 are differentially expressed by C. difficile ribotype and biofilm production level.

Molecular epidemiology of predominant and emerging Clostridioides difficile ribotypes

There has been an increase in the incidence and severity of Clostridioides difficile infection (CDI) worldwide, and strategies to control, monitor, and diminish the associated morbidity and mortality have been developed. Several typing methods have been used for typing of isolates and studying the epidemiology of CDI; serotyping was the first typing method, but then was replaced by pulsed-field gel electrophoresis (PFGE). PCR ribotyping is now the gold standard method; however, multi locus sequence typing (MLST) schemes have been developed. New sequencing technologies have allowed comparing whole bacterial genomes to address genetic relatedness with a high level of resolution and discriminatory power to distinguish between closely related strains. Here, we review the most frequent C. difficile ribotypes reported worldwide, with a focus on their epidemiology and genetic characteristics.

Comparison of Matrix-assisted Laser Desorption Ionization Time-of-flight Mass Spectrometry (MALDI-TOF MS) and the Vitek 2 System for Routine Identification of Clinically Relevant Bacteria and Yeast

OBJECTIVE

In this study, we compared the observed agreement and correlation of the Vitek 2 system with the biomarker-based MALDI-TOF MS identification results of bacteria and yeast on a routine basis.

METHODS

Clinical isolates collected from two years were included. Isolates were identified using the Vitek 2 system and MALDI-TOF MS. The percent of observed agreements and the kappa coefficient (κ) with its corresponding 95% interval confidence were calculated between both results. When species-level biotyper identifications matched a member of a group, complex, or one of the species of a slashing call, the identification was considered correct for agreement calculations.

RESULTS

The 4,238 recruited isolates included 2,669 gram-negative bacteria, 1,479 gram-positive bacteria, and 90 yeast. Among gram-negative bacteria, the most frequent species identified were Escherichia coli (κ=0.983), Acinetobacter baumannii complex (κ=0.979), Klebsiella pneumoniae (κ=0.972), and Pseudomonas aeruginosa (κ=0.970). Among Staphylococcal species, Staphylococcus aureus was the most frequently species detected (κ=0.986), followed by S. epidermidis (κ=0.904). For enterococcal species, Enterococcus faecalis (κ=0.882) and Enterococcus faecium (κ=0.849) were the most frequently detected. For yeasts, the more common species were Candida albicans (κ=0.888), followed by Candida tropicalis (κ=0.946) and Candida glabrata (κ=1.000).

CONCLUSIONS

According to our results, when antimicrobial susceptibility tests are performed using Vitek 2 cards, the most common pathogens are correctly identified for the most frequent clinical isolates.

High sporulation and overexpression of virulence factors in biofilms and reduced susceptibility to vancomycin and linezolid in recurrent Clostridium [Clostridioides] difficile infection isolates

Clostridium [Clostridioides] difficile infection (CDI) is one of the leading causes of diarrhea associated with medical care worldwide, and up to 60% of patients with CDI can develop a recurrent infection (R-CDI). A multi-species microbiota biofilm model of C. difficile was designed to evaluate the differences in the production of biofilms, sporulation, susceptibility to drugs, expression of sporulating (sigH, spo0A), quorum sensing (agrD1, and luxS), and adhesion-associated (slpA and cwp84) pathway genes between selected C. difficile isolates from R-CDI and non-recurrent patients (NR-CDI). We obtained 102 C. difficile isolates from 254 patients with confirmed CDI (66 from NR-CDI and 36 from R-CDI). Most of the isolates were biofilm producers, and most of the strains were ribotype 027 (81.374%, 83/102). Most C. difficile isolates were producers of biofilm (100/102), and most were strongly adherent. Sporulation was higher in the R-CDI than in the NR-CDI isolates (p = 0.015). The isolates from R-CDI patients more frequently demonstrated reduced susceptibility to vancomycin than isolates of NR-CDI patients (27.78% [10/36] and 9.09% [6/66], respectively, p = 0.013). The minimum inhibitory concentrations for vancomycin and linezolid against biofilms (BMIC) were up to 100 times and 20 times higher, respectively, than the corresponding planktonic MICs. Expression of sigH, spo0A, cwp84, and agrD1 was higher in R-CDI than in NR-CDI isolates. Most of the C. difficile isolates were producers of biofilms with no correlation with the ribotype. Sporulation was greater in R-CDI than in NR-CDI isolates in the biofilm model of C. difficile. The R-CDI isolates more frequently demonstrated reduced susceptibility to vancomycin and linezolid than the NR-CDI isolates in both planktonic cells and biofilm isolates. A higher expression of sporulating pathway (sigH, spo0A), quorum sensing (agrD1), and adhesion-associated (cwp84) genes was found in R-CDI than in NR-CDI isolates. All of these factors can have effect on the recurrence of the infection.

Stenotrophomonas maltophilia in Mexico: antimicrobial resistance, biofilm formation and clonal diversity

Stenotrophomonas maltophilia is an important multidrug-resistant nosocomial pathogen associated with high mortality. Our aim was to examine antimicrobial susceptibility, biofilm production and clonal relatedness of clinical isolates of S. maltophilia. S. maltophilia isolates were collected between 2006 and 2013 from two tertiary care hospitals in Mexico. Antimicrobial susceptibility was evaluated by the broth microdilution method. PCR was used to determine the presence of β-lactamase genes L1 and L2. Biofilm formation was assessed with crystal violet staining. Clonal relatedness was determined by PFGE. Among the 119 collected S. maltophilia isolates, 73 (61.3%) were from the respiratory tract. Resistance levels exceeded 75% for imipenem, meropenem, ampicillin, aztreonam, gentamicin and tobramycin. Resistance to trimethoprim-sulfamethoxazole was 32.8%. L1 and L2 genes were detected in 77.1% (91/118) and 66.9% (79/118) of isolates, respectively. All S. maltophilia strains were able to produce biofilms. Strains were classified as weak (47.9%, 57/119), moderate (38.7%, 46/119), or strong (13.4%, 16/119) biofilm producers. A total of 89 distinct PFGE types were identified and 21.6% (22/102) of the isolates were distributed in nine clusters. This is the first study in Mexico to reveal characteristics of clinical isolates of S. maltophilia. Clonal diversity data indicate low cross-transmission of S. maltophilia in a hospital setting. The high antibiotic resistance underscores the need for continuous surveillance of S. maltophilia in hospital settings in Mexico.