Isolation and characterization of multidrug‐resistant Leclercia species from animal clinical case

Leclercia adecarboxylata, a Gram‐negative bacillus of family Enterobacteriaceae, is an uncommonly identified pathogen isolated from environmental and clinical specimens. Most of the human infections are polymicrobial and commonly occur in immunocompromised hosts, although nosocomial infections in immunocompetent hosts have been documented. Here, we describe the case of isolation of Leclercia species as polymicrobial infection from bovine suffering from respiratory distress in Chhattisgarh state of India. The isolates were identified by their phenotypes, 16S rDNA sequencing and MALDI‐TOF‐MS. The isolate was found to be resistant to aminoglycosides and fluoroquinolone antibiotics and intermediate resistant to cephalosporins and evidenced for uncertain clinical relevance and could act as hidden source of public health hazard.

Significance and Impact of the Study

Leclercia adecarboxylata is a rarely reported human pathogen. We report here the case from bovine suffering from respiratory distress; the sample yielded Leclercia species as polymicrobial culture. The isolate was found to be multidrug resistant and evidenced for uncertain clinical relevance and could act as hidden source of public health hazard. The limited literature available on this organism is reviewed, and the potential implications of findings are discussed. To the best of our knowledge, this is the first report of isolation and characterization of multidrug‐resistant Leclercia species from animal clinical case from India.     

Molecular investigation of carbapenem resistance among multidrug‐resistant Pseudomonas aeruginosa isolated clinically in Thailand

Carbapenem resistant Pseudomonas aeruginosa were isolated among multidrug‐resistant (CR‐MDR) organisms from tertiary hospitals in Thailand. Decreased expression of oprD mRNA (93.65%) was predominant followed by increased expression of mexAB‐oprM mRNA (92.06%) and mexXY mRNA (63.49%). Interestingly, 23 of 126 (18.25%) isolates were susceptible to imipenem with down‐regulated oprD expression and non‐up‐regulated mexCD‐oprJ mRNA expression. Metallo‐β‐lactamases production was clearly positive in 24 isolates (18.46%) and weakly positive in 12 isolates (9.23%). Among both of these sets of isolates, imp‐1, imp‐14 and vim‐2 were identified. Hyperproduction of AmpC β‐lactamase had the lowest prevalence rate (3.97%). It was concluded that CR‐MDR P. aeruginosa clinical isolates in Thailand possess multifactorial resistance mechanisms.     

Comparison of Salmonella enterica serotype Infantis isolates from a veterinary teaching hospital

AIMS: To compare Salmonella enterica serotype Infantis isolates obtained from patients or the environment of a veterinary teaching hospital over a period of 9 years following a nosocomial outbreak to determine whether isolates were epidemiologically related or represented unrelated introductions into the hospital environment. METHODS AND RESULTS: Fifty-six S. Infantis isolates were compared based on their phenotypic (antimicrobial drug [AMD] susceptibility pattern) and genotypic (pulsed-field gel electrophoresis [PFGE] pattern and presence of integrons) characteristics. Epidemiologically unrelated S. Infantis isolates clustered separately from all but two of the hospital isolates, and several isolates from different years and various sources were indistinguishable from each other in cluster analysis of two-enzyme PFGE results. A high percentage of isolates (80.3%) were resistant to at least one AMD, with 67.8% showing resistance to >5 AMD. The majority (74.1%) of isolates tested contained type 1 integrons. CONCLUSION: Results strongly suggest that there was nosocomial transmission of S. Infantis during the initial outbreak, and that contamination arising from this outbreak persisted across years despite rigorous hygiene and biosecurity precautions and may have led to subsequent nosocomial infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Evidence of persistence and transmission of Salmonella clones across years, even in the face of rigorous preventive measures, has important implications for other facilities that have experienced outbreaks of Salmonella infections.     

Antimicrobial activities and membrane‐active mechanism of CPF‐C1 against multidrug‐resistant bacteria,a novel antimicrobial peptide derived from skin secretions of the tetraploid frog Xenopus clivii

Hospital‐acquired infections caused by multidrug‐resistant bacteria pose significant challenges for treatment, which necessitate the development of new antibiotics. Antimicrobial peptides are considered potential alternatives to conventional antibiotics. The skin of Anurans (frogs and toads) amphibians is an extraordinarily rich source of antimicrobial peptides. CPF‐C1 is a typical cationic antimicrobial peptide that was originally isolated from the tetraploid frog Xenopus clivii. Our results showed that CPF‐C1 has potent antimicrobial activity against both sensitive and multidrug‐resistant bacteria. It disrupted the outer and inner membranes of bacterial cells. CPF‐C1 induced both propidium iodide uptake into the bacterial cell and the leakage of calcein from large liposome vesicles, which suggests a mode of action that involves membrane disturbance. Scanning electron microscopy and transmission electron microscopy verified the morphologic changes of CPF‐C1‐treated bacterial cells and large liposome vesicles. The membrane‐dependent mode of action signifies that the CPF‐C1 peptide functions freely and without regard to conventional resistant mechanisms. Additionally, it is difficult for bacteria to develop resistance against CPF‐C1 under this action mode. Other studies indicated that CPF‐C1 had low cytotoxicity against mammalian cell. In conclusion, considering the increase in multidrug‐resistant bacterial infections, CPF‐C1 may offer a new strategy that can be considered a potential therapeutic agent for the treatment of diseases caused by multidrug‐resistant bacteria. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Nosocomial infection caused by vancomycin‐susceptible multidrug‐resistant Enterococcus faecalis over a long period in a university hospital in Japan

Compared with other developed countries, vancomycin‐resistant enterococci (VRE) are not widespread in clinical environments in Japan. There have been no VRE outbreaks and only a few VRE strains have sporadically been isolated in our university hospital in Gunma, Japan. To examine the drug susceptibility of Enterococcus faecalis and nosocomial infection caused by non‐VRE strains, a retrospective surveillance was conducted in our university hospital. Molecular epidemiological analyses were performed on 1711 E. faecalis clinical isolates collected in our hospital over a 6‐year period [1998–2003]. Of these isolates, 1241 (72.5%) were antibiotic resistant and 881 (51.5%) were resistant to two or more drugs. The incidence of multidrug resistant E. faecalis (MDR‐Ef) isolates in the intensive care unit increased after enlargement and restructuring of the hospital. The major group of MDR‐Ef strains consisted of 209 isolates (12.2%) resistant to the five drug combination tetracycline/erythromycin/kanamycin/streptomycin/gentamicin. Pulsed‐field gel electrophoresis analysis of the major MDR‐Ef isolates showed that nosocomial infections have been caused by MDR‐Ef over a long period (more than 3 years). Multilocus sequence typing showed that these strains were mainly grouped into ST16 (CC58) or ST64 (CC8). Mating experiments suggested that the drug resistances were encoded on two conjugative transposons (integrative conjugative elements), one encoded tetracycline‐resistance and the other erythromycin/kanamycin/streptomycin/gentamicin‐resistance. To our knowledge, this is the first report of nosocomial infection caused by vancomycin‐susceptible MDR‐Ef strains over a long period in Japan.     

Salmonella enterica isolates from pasture‐raised poultry exhibit antimicrobial resistance and class I integrons

Aims: While considerable foodborne pathogen research has been conducted on conventionally produced broilers and turkeys, few studies have focused on free‐range (organic) or pastured poultry. The current surveillance study was designed to isolate, identify and genetically characterize Salmonella from pastured poultry farm environment and from retail samples. Methods and Results: In this study, 59 isolates were collected from two pastured poultry farms (n = 164; pens, feed, water and insect traps) and retail carcasses (n = 36) from a local natural foods store and a local processing plant. All isolates were serotyped and analysed phenotypically (antimicrobial resistance profiles) and genotypically (DNA fingerprints, plasmid profiles and integron analysis). Salmonella enterica was detected using standard microbiological methods. Salmonella Kentucky was the most prevalent serotype detected from the sampled sources (53%), followed by Salmonella Enteritidis (24%), Bareilly (10%), Mbandaka (7%), Montevideo (5%) or Newport (2%). All isolates were resistant to sulfisoxazole and novobiocin, and the majority (40/59) possessed class I integrons shown by PCR detection. Each Salmonella serotype elicited a distinct pulsed‐field gel electrophoresis fingerprint profile, and unique differences were observed among the serotypes. Conclusions: The findings of this study show that Salmonella serotypes isolated from pasture‐raised poultry exhibit antimicrobial resistance and class I integrons. Significance and Impact of the Study: This study demonstrates that despite the cessation of antibiotic usage in poultry production, antibiotic resistant Salmonella may still be recovered from the environment and poultry products.     

Combined effects of spray‐drying conditions and postdrying storage time and temperature on Salmonella choleraesuis and Salmonella typhimurium survival when inoculated in liquid porcine plasma

The objective of this study was to determine the effectiveness of the spray‐drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray‐dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray‐drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray‐drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray‐dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray‐drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.

Significance and Impact of the Study

Safety of raw materials from animal origin like spray‐dried porcine plasma (SDPP) may be a concern for the swine industry. Spray‐drying process and postdrying storage are good inactivation steps to reduce the bacterial load of Salmonella choleraesuis and Salmonella typhimurium. For both Salmonella spp., spray‐drying at 71°C or 80°C outlet temperatures reduced bacterial counts about 3 log at residence time (RT) 0 s, while there was about a 5.5 log reduction at RT 60 s. Storage of all dried samples at either 4.0 ± 3.0°C or 23.0 ± 0.3°C for 15 days was effective for eliminating detectable bacterial counts of both Salmonella spp.