Antimicrobial Activity of Agarwood Oil Against Multiple-Drug-Resistant (MDR) Microbes of Clinical, Food and Environmental Origin.

BACKGROUND AND OBJECTIVES: Multiple-Drug-Resistance (MDR) among bacteria is an imminent problem and alternative therapies are seen as a future abode. Agarwood Oil (AO) is described to possess antimicrobial activity besides many other medicinal utilities. This paper discusses the antimicrobial activity of AO on MDR and non-MDR strains of microbes of 69 genera isolated from clinical and non-clinical samples. METHODS AND RESULTS: In this study sensitivity of microbes was determined for conventional antimicrobials and AO using disc diffusion assay followed by determination of minimum inhibitory concentration (MIC) using agar well dilution assay. A total of 18.5% (522) strains were found sensitive to AO. Carbapenem resistant bacterial strains were more often (p, ≤0.01) resistant to antibiotics with 4.2 times more odds (99% CI, 2.99-5.90) of being MDR than carbapenem sensitive strains but no difference in their AO sensitivity was observed. However, MDR strains were more often (p, <0.001) resistant to AO than non-MDR strains. Bacteria isolated from dogs were more often sensitive to AO than those from buffaloes, human, horse, and cattle. On the other hand, bacteria from pigs were more often (p, ≤0.05) resistant to AO than bacteria from human, cattle, buffaloes, dogs, wild carnivores and birds. Oxidase positive Gram positive bacteria had 4.29 (95% CI, 2.94-6.27) times more odds to be AO sensitive than oxidase negative Gram negative bacteria. Bacillus species strains were the most sensitive bacteria to AO followed by strains of Streptococcus and Staphylococcus. The MIC of AO for different bacteria ranged from 0.01 mg/mL to > 2.56 mg/mL. CONCLUSION: The study concluded that MDR and AO resistance had a similar trend and AO may not be seen as a good antimicrobial agent against MDR strains.

Inhibitory effect of grapefruit seed extract (GSE) on avian pathogens.

The inhibitory activities of grapefruit seed extract (GSE) on avian influenza virus (AIV), Newcastle disease virus (NDV), infectious bursal disease virus (IBDV), Salmonella Infantis (SI) and Escherichia coli (EC) were evaluated. Original GSE contained 0.24% benzalkonium chloride (BZC), however, 0.0025% BZC solution could not inactivate bacteria. The activity of diluted GSE (×100, ×500 and ×1,000 with redistilled water) against selected viruses and bacteria was evaluated in this study. The GSE solutions were incubated with the pathogens over a period of time after which the remaining viruses were titrated and the bacterial colonies were counted. In the presence of organic material-5% fetal bovine serum (FBS), the test solutions were sprayed at 1 cm and 30 cm distances to test the efficacy of GSE in a spray form. Furthermore, the efficacy of GSE against bacteria on clothes was tested using non-woven cloth. GSE×100 reduced the viral titer of both AIV and NDV even in 5% FBS condition. IBDV showed high resistance to GSE. GSE×1,000 inactivated both SI and EC within 5 sec, even in the presence of 5% FBS. The disinfectant was able to maintain its efficacy in the spray form at 30 cm distance. GSE was also effective against SI and EC inoculated on fabric. GSE is a potential novel disinfectant against viruses and bacteria, effective even within a short contact time.

Molecular epidemiology of colistin-resistant Enterobacteriaceae in inpatient and avian isolates from China: high prevalence of mcr-negative Klebsiella pneumoniae.

Whether chromosomal and transmissible mechanisms contribute simultaneously to colistin resistance in Klebsiella pneumoniae and Escherichia coli remains unknown. This study aims to identify the underlying mechanisms of colistin resistance in inpatient and avian K. pneumoniae and E. coli in China. We retrospectively screened 2353 Enterobacteriaceae isolates from inpatients at multiple centers during 2011-2014, and 168 avian isolates from one slaughterhouse in 2013 for the presence of MCR-1/MCR-2. Mutations and transcriptional levels of the chromosomal RamA, PhoPQ, and PmrAB genes were determined by PCR and RT-qPCR. The transferability and genetic characteristics of the underlying colistin-resistance genes were detected by conjugation and whole-genome sequencing. The MIC90 for colistin in colistin-resistant K. pneumoniae (ColRKP, 128 mg/L, N = 17) was 16-fold higher than in colistin-resistant E. coli (ColREC, 8 mg/L, N = 33). The dominant sequence types of ColRKP were ST2018 and ST37, whereas ColREC displayed diversity. The chromosomal genes ramA, pmrB, and phoQ were not associated with colistin resistance in ColRKP. The transcriptional levels of PmrB in ColREC were 7.5-fold greater than in colistin-susceptible isolates. The carrying rates of MCR-1 in ColREC and ColRKP were 100% (33/33) and 23.5% (4/17), respectively. Plasmid IncI2 (~60 kb) carrying MCR-1 could be transferred to recipient E. coli EC600 with frequencies ranging from 8.74 × 10-6 to 1.31 × 10-4. No transferable genes were identified in mcr-1-negative ColRKP. MCR-1 combined with upregulated PmrB was associated with low-level colistin resistance in ColREC. However, two-thirds of the ColRKP isolates were mcr-negative and need to be studied further.

Structural analysis of raw and commercial farm edible bird nests.

Edible bird nests (EBNs) are consumed worldwide for various health benefits. EBNs are nests built from the saliva of swiftlets of Aerodramus species. The global market for EBNs is on the rise, especially from Hong Kong and mainland China. In the past, EBNs were harvested mainly from natural caves; however in the recent years, there has been a rapid growth of swiftlet farming. Little is known about the actual composition of EBNs except for protein, carbohydrate, ash and lipid contents, amino acids, vitamins and macro/ micronutrients. Besides the biochemical components of EBNs, are there any other structures that are associated with EBNs? This paper reports on the structural analysis of raw unprocessed farm and processed commercial EBNs. The raw EBNs were purchased from swiftlet farms in five locations in Peninsula Malaysia: Kuala Sanglang (Perlis; 6° 16' 0"N, 100° 12' 0"E), Pantai Remis (Perak; 4º 27' 0" N, 100º 38' 0" E), Kluang (Johor; 02º 012 303N 103º 192 583E), Kajang (Selangor; 2º 59' 0"N, 101º 47' 0"E) and Kota Bharu (Kelantan; 6º 8' 0"N, 102º 15' 0"E). The commercial nests were purchased from five different Chinese traditional medicinal shops (Companies A-E). A portion of each EBN was randomly broken into small fragments, attached to carbon tape and coated with gold and palladium particles for examination and photography under a scanning electron microscope. Structural analysis revealed the presence of mites, fungi, bacteria and feather strands on both the raw and commercial nests. Mite eggshells and faecal pellets, and body parts of other arthropods were seen only in the raw nests. The commercial nests had a variety of unidentified structures and substances coated on the nests' surfaces that were not found on the raw nests. The presence of these contaminants may jeopardise the quality of EBNs and pose health risks to consumers. Further identification of the mites and their allergens, fungi and bacteria are on-going and will be reported separately.

Cyanophycin-degrading bacteria in digestive tracts of mammals, birds and fish and consequences for possible applications of cyanophycin and its dipeptides in nutrition and therapy.

AIMS: To determine the susceptibility of cyanophycin granule polypeptide (CGP) to degradation by several mammalian, avian and fish gut flora. METHODS AND RESULTS: Samples of gut flora were investigated for the occurrence of bacteria capable of CGP degradation. With all samples, a complete anaerobic degradation of CGP was achieved over incubation periods of only 12-48 h at 37 degrees C. CGP-degrading bacteria were detected in all samples, and they occurred in particular high titres in caecum flora from rabbit and sheep and in the digestive tract of carp fish. A total of 62 axenic cultures were isolated. All degraded CGP aerobically, 46 of them degraded CGP also anaerobically over incubation periods ranging from 24 h to 7 days. HPLC analysis revealed that all isolates degraded CGP to its constituting dipeptides. Eight strains were identified by 16S rRNA gene sequencing and were affiliated to the genera Bacillus, Brevibacillus, Pseudomonas, Streptomyces and Micromonospora. CONCLUSIONS: These data demonstrate for the first time the occurrence of a natural niche for CGP in the digestive tracts of animals. SIGNIFICANCE AND IMPACT OF THE STUDY: The biodegradability of CGP by gut flora provides a first confirmation for the potential applications of CGP and its dipeptides in nutrition and therapy as highly bio-available sources for arginine, lysine, aspartate and possibly also other amino acids.

A SitABCD homologue from an avian pathogenic Escherichia coli strain mediates transport of iron and manganese and resistance to hydrogen peroxide.

An operon encoding a member of the family of ATP-binding cassette (ABC) divalent metal ion transporters, homologous to Salmonella enterica SitABCD, has been identified in the avian pathogenic Escherichia coli (APEC) strain chi7122. The sitABCD genes were located on the virulence plasmid pAPEC-1, and were highly similar at the nucleotide level to the chromosomally encoded sitABCD genes present in Shigella spp. A cloned copy of sitABCD conferred increased growth upon a siderophore-deficient E. coli strain grown in nutrient broth supplemented with the chelator 2,2'-dipyridyl. Ion rescue demonstrated that Sit-mediated growth promotion of this strain was due to the transport of iron. SitABCD mediated increased transport of both iron and manganese as demonstrated by uptake of 55Fe, 59Fe or 54Mn in E. coli K-12 strains deficient for the transport of iron (aroB feoB) and manganese (mntH) respectively. Isotope uptake and transport inhibition studies showed that in the iron transport deficient strain, SitABCD demonstrated a greater affinity for iron than for manganese, and SitABCD-mediated transport was higher for ferrous iron, whereas in the manganese transport deficient strain, SitABCD demonstrated greater affinity for manganese than for iron. Introduction of the APEC sitABCD genes into an E. coli K-12 mntH mutant also conferred increased resistance to the bactericidal effects of hydrogen peroxide. APEC strain chi7122 derivatives lacking either a functional SitABCD or a functional MntH transport system were as resistant to hydrogen peroxide as the wild-type strain, whereas a Deltasit DeltamntH double mutant was more sensitive to hydrogen peroxide. Overall, the results demonstrate that in E. coli SitABCD represents a manganese and iron transporter that, in combination with other ion transport systems, may contribute to acquisition of iron and manganese, and resistance to oxidative stress.

Ground red hot pepper agar in the isolation and presumptive identification of Cryptococcus neoformans.

The study compared ground red hot pepper agar (GRHP) and Guizotia abyssinica creatinine agar (GACA), a medium routinely used for isolation of Cryptococcus neoformans. In order to confirm the capacity of GRHP to support the Cr. neoformans growth and pigment production, 15 strains were inoculated onto GRHP and GACA. No significant differences in the growth and pigmentation of the tested strains on the two media were noted. As heavily contaminated specimens, 50 samples of pigeon droppings were examined by plating on GRHP and GACA, which resulted in the isolation of 14 and nine Cr. neoformans strains, respectively. The results indicate that GRHP, as a result of its superior selectivity and significant reduction of contaminant growth, provides better conditions than GACA for isolation and presumptive identification of Cr. neoformans from heavily contaminated specimens.

Epidemiology of Yersiniae in Barcelona, Spain.

Between April 1980 to December 1984 we undertook a study on the epidemiology of pathogenic Yersinia. Stool specimens from 5.199 patients with acute gastroenteritis were studied and Y. enterocolitica biotype 4 serotype 3 was isolated in 42 cases (0.8%). The serological response was studied in 21 of these patients. Faecal specimens from 784 non-laboratory animals were also studied. The only pathogenic isolates from these animals were seven strains of Y. enterocolitica biotype 4 serotype 3 from six pigs and one dog and one strain of Y. pseudotuberculosis from a pig. The search of pathogenic Yersinia in 424 samples form row foods allowed the isolation of eight strains of Y. enterocolitica serotype 3 and one strain of Y. pseudotuberculosis from pig's tongue.

The effect of the use of different selective media on the ability to recover salmonellae from seagull faeces.

Solid media were compared for their ability to recover salmonellae from seagull faecal material after pre-enrichment in buffered peptone water and enrichment in Rappaport's broth. Of the 847 specimens examined 96 were found to be positive for salmonellae. Use of Brilliant Green agar containing sulphamandelate supplement resulted in the detection of salmonellae from each of the 96 samples found to be positive and was the most efficient medium tested. Brilliant Green agar lacking the supplement was the least effective medium, salmonellae being isolated from only 80 samples using this medium. All of the media tested were shown to support the growth of a wide range of salmonella serotypes, although Salmonella typhi and S. dublin did not form colonies on those media which contained Brilliant Green. Hynes' modification of deoxycholate citrate agar was shown to be considerably less inhibitory to salmonellae after ageing for four days. Ageing of other media had no significant affect on their ability to support the growth of salmonellae.