Gut microbiota in burned patients with Clostridioides difficile infection.

BACKGROUND: The survival rate of patients with severe burn is positively associated with increasing the incidence of the Clostridioides difficile (C. difficile) infection (CDI). The surviving rate of severe burn patients now has an improved but the incidence of Clostridioides difficile (C. difficile) infection (CDI) has been continues increasing during recent two decades. This study assessed the molecular typing and phenotypic characterization isolates of C. difficile in burn patients with diarrhea, as well as environmental and skin infections with C. difficile spores at a referral burn hospital in Isfahan, Iran. It mainly aimed to evaluate the dominant bacterial structure in the gut microbiome of burned subjects with and without CDI. METHODS: In general, 309 samples were collected from 189 burned patients with hospital-acquired diarrhea and 120 swabs were collected from the healthcare workers' dominant hands, different sites of patients' skin, and medical tools. In addition, C. difficile isolates were characterized considering the existence of antibiotic resistance and toxin genes. Clinical cultures with identification of organisms and antibiotic susceptibility were done. C. difficle isolates were then genotyped and compared to clinical outcomes. Finally, the clinical characteristics of the participants were gathered through their records, and the bacterial targets of the gut microbiome were detected using quantitative real-time polymerase chain reaction (PCR). RESULTS: Based on the findings, 51 C. difficile isolates were detected from 189 severe burn patients hospitalized in the hospital. Further, PCR amplification tcdB and tcdA showed 23 isolates (12.2%) as toxigenic. Overall, 18.3% (22/120) of skin and environment samples demonstrated a positive result for C. difficile colonization. A low concentration of metronidazole and vancomycin (MIC90, 0.5, and 1.2 mg/L) inhibited all toxigenic C. difficile strains. Moreover, these isolates represented the highest rates of resistance to moxifloxacin and clindamycin (MIC90, 0.5, and 1.6 mg/L). A significantly reduced abundance of Clostridium spp., Bacteroidetes, and Bifidobacterium and an increase in the quantity of Firmicutes was observed in the gastrointestinal microbiome of burn patients (P < 0.01). Burn patients with CDI showed a significant decrease in Faecalibacterium prausnitzii (F. prausnitzii) while higher Akkermansia muciniphila (A. muciniphila) loads in comparison with healthy controls (P < 0.001 and P < 0.05). Contrarily, burned cases displayed increased levels of opportunistic pathogenic bacteria including the members of Enterococcus spp. and Escherichia coli (P < 0.05). CONCLUSIONS: Despite appropriate infection control strategies in the burn intensive care unit, CDI remains prevalent in severe burn patients. Eventually, the overgrowth of A. muciniphila and the decreased abundance of F. prausnitzii in burn cases with CDI could be potential predictive microbiome biomarkers in burned patients.

Evaluation of Biofilm Formation and Frequency of Multidrug-resistant and Extended Drug-resistant Strain in Pseudomonas aeruginosa Isolated from Burn Patients in Isfahan.

BACKGROUND: Pseudomonas aeruginosa is a biofilm-forming bacterium which can result in serious health problems, particularly in burn patients. Biofilm has been assumed to protect the bacteria from environmental fluctuations such as antimicrobial agent. Mucoid strains generate extensive levels of the alginate exopolysaccharide, which is an important factor of its biofilm. MATERIALS AND METHODS: Totally, 100 isolates of P. aeruginosa has been gathered from wound infections of burn patients. Polymerase chain reaction of exoA gene has been carried out to confirm the bacteriologic identification of isolates. The biofilm-forming capacity has been specified by capsule staining and microtiter plate test as qualitative and quantitative determination, respectively. Antimicrobial susceptibility of the isolates has been specified by disk diffusion method. RESULTS: All the isolates carried the exoA gene. The antibiotic resistance was imipenem (90%); levofloxacin (93%); aztreonam (87%); piperacillin-tazobactam (85%); tobramycin (92%); polymyxin b (PB) (2%); and ceftazidime (CAZ) (32%). Totally, multidrug-resistant (MDR) and extended drug-resistant (XDR) isolates were 19% and 75%, respectively. Fortunately, pan drug-resistant (PDR) strain has not been observed. The assessment of biofilm formation has shown that 7% of the isolates were nonbiofilm (N), weak (W) 67%, moderate (M) 22%, and strong (S) 4%. CONCLUSIONS: As a result, the findings of this survey indicated that PB and CAZ were the most effective antibiotics against P. aeruginosa, which of course indicate a serious problem about the emergence of the PDR strains. There was no relationship between the patterns of biofilm production and antibiotic susceptibility, but high frequency of MDR/XDR and biofilm producer strains has been detected.

Distribution of the Strains of Multidrug-resistant, Extensively Drug-resistant, and Pandrug-resistant Pseudomonas aeruginosa Isolates from Burn Patients.

BACKGROUND: Pseudomonas aeruginosa is an opportunistic and Gram-negative pathogen that is used as the most important factor in burn wound infections, and due to the rapid acquisition of multidrug resistance (MDR), it causes high mortality rates in these sectors. Thus, diagnosis and assessment of antibiotic resistance patterns are very important in these patients. The aim of this study was to evaluate antibiotic resistance pattern and determining P. aeruginosa MDR. MATERIALS AND METHODS: In this study, phenotypic, biochemical, and polymerase chain reaction tests were used to identify P. aeruginosa from 120 wound burn samples that 96 samples were detected to P. aeruginosa species. In the next step, according to the Clinical and Laboratory Standard Institute standard guidelines, antibiogram test was performed by disk diffusion method for amikacin, ciprofloxacin, norfloxacin, gentamicin, cefepime, aztreonam, meropenem, colistin, ceftazidime, and piperacillin-tazobactam antibiotics. Antibiotic data were analyzed by WHONET software; finally, the rate of antibiotic resistance and MDR strains was determined. RESULTS: The highest antibiotic resistance belonged to amikacin (94.8%) and norfloxacin (90.6%); in contrast, colistin (8.3%) had the lowest and the MDR strains were MDR (95.8%) and extensively drug resistance (XDR) (87.5%). CONCLUSION: In this study, there was MDR with an alarming rate including MDR (95.8%), XDR (87.5%), and pan-drug resistance (0%). As a result, given antibiotics to patients should be controlled by the antibiogram results to avoid increasing MDR strains.

Identification of Genomic Species of Acinetobacter Isolated from Burns of ICU Patients.

BACKGROUND: The worldwide emergence of multi-drug resistant (MDR) bacteria in recent years has caused many problems for hospitals and patients, especially intensive care unit patients. Among these clinically important MDR bacteria are Acinetobacter baumannii complex species (A. baumannii, Acinetobacter genomic species 3 and Acinetobacter genomic species 13TU) that cause a wide range of infections. METHODS: The sequencing and bioinformatics analysis of a part of the Zone 1 of rpoB gene was performed for species identification of Acinetobacter isolates obtained from ICU patients with infected burns hospitalized in a hospital in Isfahan, Iran, over a 9-month period. Antibiotic sensitivity of Acinetobacter isolates was investigated using the disk diffusion method and different classes of antibiotics including amikacin, cefotaxime, ceftriaxone, ciprofloxacin, imipenem and piperacillin. RESULTS: Acinetobacter spp. were isolated from 10 of 80 (12.5%) investigated patients. All of the 10 Acinetobacter isolates were identified as Acinetobacter baumannii and multi-drug resistant according to antibiotic susceptibility tests. CONCLUSION: Of the Acinetobacter baumannii complex members, only A. baumannii species was identified among the isolates obtained from patients with infected burns in an Isfahan hospital over a 9-month period.

Efflux pump regulatory genes mutations in multidrug resistance Pseudomonas aeruginosa isolated from wound infections in Isfahan hospitals.

BACKGROUND: Multidrug resistance Pseudomonas aeruginosa (MDR-P. aeruginosa) is a worldwide threat for public health. Hyperexpression of efflux pump systems (MexAB-OprM and MexCD-OprJ), which is a well-known mechanisms for MDR emerging, is controlled by regulatory genes, mexR and nfxB, respectively. The aim of this study was to evaluate point mutations in mexR and nfxB genes in MDR- P. aeruginosa isolated from wound infections. MATERIALS AND METHODS: A total of 34 P. aeruginosa cultures obtained from wound infections were analyzed. Among them eight isolates identified as MDR-P. aeruginosa and were subjected to determination of mutations in mexR and nfxB genes. RESULTS: We detected eight-point mutations in mexR and 12-point mutations in nfxB. The most common mutations were common G327-A (eight isolates), G384-A (eight isolates), G411-A (eight isolates). Mutations in A371-C and A372-C were the predominant substitution which was seen in nfxB. Amino acid substitutions were also found at position 124 and 126 for NfxB and MexR, respectively. CONCLUSIONS: P. aeruginosa isolates with mutation in efflux pump regulatory genes such as mexR and nfxB could be a main factor contributed to antibiotic resistance and must be considered in antibiotic treatment.