Antimicrobial and anti-biofilm efficacy of different inorganic and organic zinc forms against multidrug-resistant Escherichia, Klebsiella, Staphylococcus and Pseudomonas.

In our study antibacterial and anti-biofilm efficacy of 2 inorganics (Zn(II) sulphate monohydrate; Zn(II) sulphate heptahydrate) and 3 organic Zn(II) substances (Zn(II) chelate of protein hydrolysate: Zn-Bio; Zn(II) chelate of amino acid hydrate: Zn-AMK; Zn(II) chelate of glycine hydrate: Zn-Gly) were explored and compared against multidrug resistant Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Klebsiella oxytoca (K. oxytoca) and Pseudomonas aeruginosa (P. aeruginosa) using by the 96- wells microtiter plate-based resazurin and/or crystal violet assay. Our finding confirmed that Zn(II)-sulphates and Zn(II)-amino acid complexes exhibit dose and genus-based antibacterial and anti-biofilm potential. Organic compounds (Zn-AMK and Zn-Gly) were more effective against bacterial growth, except P. aeruginosa. Besides Zn-AMK, others organic and inorganic forms of Zn(II) caused predominantly statistically significant decrease of biofilm production in all of tested bacteria. Current data highlights that Zn(II) in various forms has a great potential to be developed as antibacterial and anti-biofilm agents.

Virulence determinants and antibiotic resistance in staphylococci isolated from the skin of captive bred reptiles.

Knowledge of the composition and properties of skin microbiota in healthy reptiles is essential for preservation strategies and thus the prevention of skin dysbiosis leading to dermatological diseases. Despite the greatly increasing popularity of reptiles as pets, only a few studies have dealt with this topic. Therefore, the aim of this work was to analyse species composition of bacteria isolated from skin swabs of 40 reptiles (17 species) using MALDI-TOF spectrometry and to characterise the virulence properties of identified staphylococci (n = 51). The most common species were Staphylococcus xylosus and S. sciuri. Bacilli, enterococci, Escherichia coli, Salmonella sp. and Acinetobacter sp. were also common. The most frequent antimicrobial resistance in staphylococcal isolates was observed for ampicillin (100.0%) and cefoxitin (98.0%) with the blaZ gene being most prevalent (58.8%). In contrast, all staphylococci were susceptible to gentamicin, kanamycin and imipenem. Slime and biofilm production was observed in 86.3% and 76.5% of isolates, respectively. Gelatinase, DNase, protease and lipase activity was found more rarely (41.2%; 25.5%; 27.5% and 21.6%). Since reptiles are a reservoir of bacteria for their owners, common multi-drug resistance (84.3%, MAR index average 0.29 ± 0.09) and biofilm formation must be kept in mind, especially in the case of injury when handling reptiles.

Distribution of virulence-associated genes, antibiotic resistance and phylogenetic groups in Escherichia coli isolated from domestic and racing pigeons.

Despite a lot of information about virulence and resistance of Escherichia coli (E. coli) in poultry, very limited data are currently available on its occurrence in pigeon isolates, although this poses a threat to human and animal health. Therefore, this study was conducted to explore the phylogenetic classification, antibiotic sensitivity, and virulence factors in E. coli isolated from cloacal swabs of domestic pigeons bred for meat (n = 47) and racing pigeons (n = 44). The most frequent phylogroup in racing pigeons was E (36, 82.00%), unlike domestic pigeons (B2- 19, 40.00%). The most abundant iron uptake system in both groups of bird was feoB (racing = 40, 90.90%; domestic = 44, 93.61%). The presence of ibeA (52, 57.10%) and kpsMTII (46, 50.50%) genes was detected in more than half of all strains belonging exclusively to phylogroups B2, D, E, F, clade I. Antibiotic resistance was higher in racing pigeons. All racing pigeon isolates were resistant to tetracycline and trimethoprim + sulphonamide. Resistance to ciprofloxacin was determined in three isolates (6.38%) of domestic and 33 isolates (75%) of racing pigeons. Aminoglycosides and ß-lactamases resistance were also recorded. One of the important detected phenotypic mechanisms of resistance occurring in isolates from racing pigeons was AGL AAC(6´)I. Our study confirms that healthy pigeons are a reservoir of antibiotic-resistant E. coli containing an arsenal of virulence factors, thus capable of potentially causing infection. Pigeons with the option to fly to multiple places can transfer virulent and resistant bacteria. Direct contact with pigeons and their faeces and the contamination of water and food pose a threat of infection to humans and other animal species.

Antimicrobial activity of organic acids against canine skin bacteria.

Canine skin is often a source of bacterial strains that are characterized by the presence of important virulence factors and a high antimicrobial resistance. These bacteria are involved in the pathogenesis of infectious skin diseases, which are very frequent in dogs. Moreover, canine skin isolates are easily spread to other animals and humans. The aim of this study was to evaluate the inhibitory and bactericidal activity of eight organic acids (L-lactic, acetic, propionic, butyric, citric, succinic, glycolic, L-ascorbic acid) against 14 canine skin isolates (11 Gram-positive and three Gram-negative species). The advantages of the tested organic acids are their gentleness to the skin and their affordability. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the broth microdilution method. All tested acids showed a bactericidal effect against the selected bacteria, with the exception of their bacteriostatic effect against the Bacillus cereus strain. The lowest MIC showed acetic acid (MIC between 0.5 and 2.0 mg/mL) and propionic acid (MIC 0.8 - 3.3 mg/mL), whereas L-ascorbic acid (MIC 4.0 - 16.0 mg/mL) seems to be weaker among the tested acids. Two Staphylococcus aureus strains and a strain of Escherichia coli were observed to be more resistant compared to coagulase-negative staphylococci.

The effect of exposure to non-ionising radiofrequency field on Escherichia coli, Klebsiella oxytoca and Pseudomonas aeruginosa biofilms.

An environment with a higher accumulation of electromagnetic non-ionising radiofrequency (RF) emissions generated by various telecommunication, data transport and navigation devices (mobile phones, Wi-Fi, radar, etc.) may have a major impact on biological systems. This study aimed to evaluate the incidence of an electromagnetic field (EMF) on the development of bacterial biofilm. Quantification of biofilm production was done by using microtiter plate assay. Bacterial isolates of Escherichia coli, Klebsiella oxytoca and Pseudomonas aeruginosa were exposed with EMF of frequencies 1-5 and 2.4 GHz with an exposure time 3 or 24 h, respectively. Exposure of bacteria to EMF produced a statistically significant increase in biofilm production mainly at 1, 2 and 4 GHz, and in contrast, a significant inhibition of biofilm development occurred at frequencies 3 and 5 GHz, both with exception of K. oxytoca and P. aeruginosa. Wi-Fi operating at 2.4 GHz caused biofilm reduction. The results indicate that EMF exposure act on bacteria in both ways, depending on the frequency: as stressful by enhancing bacterial biofilm formation (under environmental stress, bacteria produce a polysaccharide matrix and aggregate to form biofilms to increase virulence and resistance), although some frequencies leading to biofilm damage could be caused by changes to the physicochemical properties of bacteria.

Distribution and Characterization of Staphylococci Isolated From Healthy Canine Skin.

Despite increasing interest to study skin microbiota with progressive methods, there are almost no data on staphylococcal species distribution on skin of healthy dogs available. Therefore we decide to characterize staphylococci isolated from 8 different body sites (inner pinna, chin, nasal skin, back, axilla, abdomen, interdigital area and perianal region) of healthy canine skin. A total of 91 staphylococci were isolated from 30 dogs living in East Slovakia. Swabs of each dog were cultivated and colonies analysed using MALDI-TOF spectrometry. The vast majority of isolated staphylococci belonged to S pseudintermedius species (48%) followed by S hominis (15%) and S aureus (10%). S haemolyticus, S warneri, S epidermidis, S capitis, S xylosus, S pasteuri, S intermedius and S succinus were also isolated (<10%). The most frequent resistance in staphylococcal isolates was observed for chloramphenicol (73%) and penicillin (67%) followed by erythromycin (42%), tetracycline (26%), and oxacillin (20%). Multi-drug resistance was found in 50% of isolates. All strains were gentamicin and vancomycin sensitive and were strong or moderate biofilm producers with high acid and alkaline phosphatase activities. Over half of strains were haemolytic (57%) and produced gelatinase (54%), DNAse (84%) and lipase (64%). It seems, multiresistant biofilm forming staphylococci could be commonly detected also in healthy dogs and could probably serve as reservoir for other dogs or owners because of constant exchange of their microbiota.

Antimicrobial Susceptibility and Detection of Virulence-Associated Genes in Escherichia coli Strains Isolated from Commercial Broilers.

The aim of this study was to investigate the presence of iron-uptake and virulence genes, antibiotic resistance profiles, and phylogenetic relatedness in 115 Escherichia coli (E. coli) strains isolated from broilers in Slovakia and to determine their potential threat to human health. The most frequent phylogroups were B1 (37%) and A (21%), and 33.9% strains were included in pathogenic groups. The commonly observed iron-uptake genes were feoB (94%), sitA (83%), and iutA (58%). Protectins (iss, kpsMTII) were identified in 30% of samples. Four percent of B2-associated broilers carried the papC (P fimbria) gene connected with upper urinary tract infection. The dominant resistance was to tetracycline (49%), ampicillin (66%), ampicillin + sulbactam (27%), ciprofloxacin (61%), and trimethoprim + sulfonamide (34%); moreover, sporadically occurring resistance to cephalosporins, aminoglycosides, fluoroquinolones, and polypeptide colistin was observed. Genotypic analysis of resistance revealed the presence of blaCTX-M-1 and blaCTX-M-2 in two isolates from broilers. Commercial broilers can be reservoirs of virulent and resistant genes as well as E. coli causing (extra-)intestinal infections, which can be a potential threat to humans via direct contact and food.

Escherichia coli Specific Virulence-Gene Markers Analysis for Quality Control of Ovine Cheese in Slovakia.

Shiga toxin-producing and extra-intestinal pathogenic Escherichia coli (E. coli) have the potential to spread through faecal waste, resulting in contamination of food and causing foodborne disease outbreaks. With the aim of characterizing unpasteurized ovine cheese in Slovakia, a total of 92 E. coli strains were examined for eleven representative virulence genes typical for (extra-)intestinal pathogenic E. coli and phylogenetic grouping. Phylogenetic groups B1 (36%) and A (32%) were the most dominant, followed by groups C (14%) and D (13%), while the lowest incidence was recorded for F (4%), and E (1%), and 43 (47%) samples carried at least one virulent gene, i.e., potential pathogens. Isolates present in groups E, F and D showed higher presence of virulence genes (100%, 75%, and 67%), versus 55%, 39%, and 28% in commensal B1, C, and A, respectively. Occurrence of papC and fyuA (both 24%) was highest, followed by tsh, iss, stx2, cnf1, kpsII, cvaC, stx1, iutA and eaeA. Nine E. coli strains (almost 10% of all tested and around 21% of our virulence-gene-associated isolates) harboured stx1, stx2 or eae. Ovine cheeses in Slovakia are highly contaminated with E. coli including potentially pathogenic strains capable of causing intestinal and/or extra-intestinal diseases, and thus may pose a threat to public health while unpasteurized.

Antibiotic Resistant and Biofilm-Associated Escherichia coli Isolates from Diarrheic and Healthy Dogs.

Bacteria isolated from companion animals are attracting concerns in a view of public health including antimicrobial resistance and biofilm development, both contributing to difficult-to-treat infections. The purpose of this study was to evaluate the minimum inhibitory concentrations (MIC) of 18 antibiotics in Escherichia coli isolated from two groups of dogs (healthy and diarrheic). Isolates were classified into phylogroups, examined for the presence of resistance genes and biofilm-formation capacity. In healthy dogs, phylogenetic analysis showed that 47.37% and 34.22% of E. coli isolates belonged to commensal groups (A; B1) in contrast to diarrheic dogs; 42.2% of isolates were identified as the B2 phylogroup, and these E. coli bacteria formed a stronger biofilm. The results of healthy dogs showed higher MIC levels for tetracycline (32 mg/L), ampicillin (64 mg/L), ciprofloxacin (8 mg/L) and trimethoprim-sulphonamide (8 mg/L) compared to clinical breakpoints. The most detected gene encoding plasmid-mediated resistance to quinolones in the healthy group was qnrB, and in dogs with diarrhea, qnrS. The resistance genes were more frequently detected in healthy dogs. The presence of the integron int1 and the transposon tn3 increases the possibility of transfer of many different cassette-associated antibiotic-resistance genes. These results suggest that dogs could be a potential reservoir of resistance genes.