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134500.9900Toxigenic potential and antimicrobial susceptibility of Bacillus cereus group bacteria isolated from Tunisian foodstuffs. BACKGROUND: Despite the importance of the B. cereus group as major foodborne pathogens that may cause diarrheal and/or emetic syndrome(s), no study in Tunisia has been conducted in order to characterize the pathogenic potential of the B. cereus group. The aim of this study was to assess the sanitary potential risks of 174 B. cereus group strains isolated from different foodstuffs by detecting and profiling virulence genes (hblA, hblB, hblC, hblD, nheA, nheB, nheC, cytK, bceT and ces), testing the isolates cytotoxic activity on Caco-2 cells and antimicrobial susceptibility towards 11 antibiotics. RESULTS: The entertoxin genes detected among B. cereus isolates were, in decreasing order, nheA (98.9%), nheC (97.7%) and nheB (86.8%) versus hblC (54.6%), hblD (54.6%), hblA (29.9%) and hblB (14.9%), respectively encoding for Non-hemolytic enterotoxin (NHE) and Hemolysin BL (HBL). The isolates are multi-toxigenic, harbouring at least one gene of each NHE and HBL complexes associated or not to bceT, cytK-2 and ces genes. Based on the incidence of virulence genes, the strains were separated into 12 toxigenic groups. Isolates positive for cytK (37,9%) harbored the cytK-2 variant. The detection rates of bceT and ces genes were 50.6 and 4%, respectively. When bacteria were incubated in BHI-YE at 30 °C for 18 h and for 5 d, 70.7 and 35% of the strains were shown to be cytotoxic to Caco-2 cells, respectively. The cytotoxicity of B. cereus strains depended on the food source of isolation. The presence of virulence factors is not always consistent with cytotoxicity. However, different combinations of enterotoxin genetic determinants are significantly associated to the cytotoxic potential of the bacteria. All strains were fully sensitive to rifampicin, chloramphenicol, ciprofloxacin, and gentamycin. The majority of the isolates were susceptible to streptomycin, kanamycin, erythromycin, vancomycin and tetracycline but showed resistance to ampicillin and novobiocin. CONCLUSION: Our results contribute data that are primary to facilitate risk assessments in order to prevent food poisoning due to B. cereus group.201931445510
134410.9889Antibiotics resistance and toxin profiles of Bacillus cereus-group isolates from fresh vegetables from German retail markets. BACKGROUND: This study aimed to evaluate the safety of raw vegetable products present on the German market regarding toxin-producing Bacillus cereus sensu lato (s.l.) group bacteria. RESULTS: A total of 147 B. cereus s.l. group strains isolated from cucumbers, carrots, herbs, salad leaves and ready-to-eat mixed salad leaves were analyzed. Their toxinogenic potential was assessed by multiplex PCR targeting the hemolysin BL (hbl) component D (hblD), non-hemolytic enterotoxin (nhe) component A (nheA), cytotoxin K-2 (cytK-2) and the cereulide (ces) toxin genes. In addition, a serological test was used to detect Hbl and Nhe toxins. On the basis of PCR and serological results, none of the strains were positive for the cereulide protein/genes, while 91.2, 83.0 and 37.4% were positive for the Hbl, Nhe and CytK toxins or their genes, respectively. Numerous strains produced multiple toxins. Generally, strains showed resistance against the β-lactam antibiotics such as penicillin G and cefotaxim (100%), as well as amoxicillin/clavulanic acid combination and ampicillin (99.3%). Most strains were susceptible to ciprofloxacin (99.3%), chloramphenicol (98.6%), amikacin (98.0%), imipenem (93.9%), erythromycin (91.8%), gentamicin (88.4%), tetracycline (76.2%) and trimethoprim/sulfamethoxazole combination (52.4%). The genomes of eight selected strains were sequenced. The toxin gene profiles detected by PCR and serological test mostly agreed with those from whole-genome sequence data. CONCLUSIONS: Our study showed that B. cereus s.l. strains encoding toxin genes occur in products sold on the German market and that these may pose a health risk to the consumer if present at elevated levels. Furthermore, a small percentage of these strains harbor antibiotic resistance genes. The presence of these bacteria in fresh produce should, therefore, be monitored to guarantee their safety.201931706266
209120.9888Antibiotic resistance and virulence profile of Klebsiella pneumoniae isolated from wild Sumatran Orangutans (Pongo abelii). OBJECTIVE: Orangutans (Pongo abelii), as endemic primates of Indonesia, are characterized by a predominantly arboreal lifestyle. Klebsiella pneumoniae (K. pneumonia) and other Gram-negative bacteria are present in the Indigenous flora of many mammals, including orangutans. This study aimed to investigate the antibiotic resistance and virulence profile of K. pneumonia isolated from wild Sumatran orangutans. MATERIALS AND METHODS: This study investigated 10 fecal samples from wild Sumatran orangutans from the Gunung Leuser National Park, Aceh, Indonesia. Biochemical and molecular identification of K. pneumoniae using the RNA polymerase subunit b gene and detection of virulence-associated genes. In addition, molecular detection of antibiotic resistance genes was performed to characterize the resistance mechanisms in the isolates. RESULTS: K. pneumonia was detected in 6 out of 10 fecal samples from wild Sumatran orangutans. The virulence genes mrkD and entB were detected in all (100%) of the isolates, whereas wabG was identified in 83.33% of the strains. Antibiotic susceptibility testing against K. pneumoniae revealed that three isolates were susceptible to streptomycin (S) and nalidixic acid (NA), while all six isolates were susceptible to chloramphenicol and ciprofloxacin. One isolate demonstrated intermediate resistance to NA, while the remaining two exhibited intermediate resistance to S. Six isolates were resistant to ampicillin, tetracycline, and erythromycin, indicating multidrug resistance. Furthermore, antibiotic resistance genes were detected in the isolates with the following prevalence: bla (TEM) gene (six isolates; 100%), bla (SHV) (six isolates; 100%), bla (CTX-M) gene (four isolates; 66.67%), and tetA gene (four isolates; 66.67%). CONCLUSION: This study revealed the virulence and resistance profile of K. pneumoniae bacterium isolated from wild Sumatran orangutans, which is essential for formulating effective conservation and healthcare strategies.202440013287
537530.9887Mechanism of Eravacycline Resistance in Clinical Enterococcus faecalis Isolates From China. Opportunistic infections caused by multidrug-resistant Enterococcus faecalis strains are a significant clinical challenge. Eravacycline (Erava) is a synthetic fluorocycline structurally similar to tigecycline (Tige) that exhibits robust antimicrobial activity against Gram-positive bacteria. This study investigated the in vitro antimicrobial activity and heteroresistance risk of Eravacycline (Erava) in clinical E. faecalis isolates from China along with the mechanism of Erava resistance. A total of 276 non-duplicate E. faecalis isolates were retrospectively collected from a tertiary care hospital in China. Heteroresistance to Erava and the influence of tetracycline (Tet) resistance genes on Erava susceptibility were examined. To clarify the molecular basis for Erava resistance, E. faecalis variants exhibiting Erava-induced resistance were selected under Erava pressure. The relative transcript levels of six candidate genes linked to Erava susceptibility were determined by quantitative reverse-transcription PCR, and their role in Erava resistance and heteroresistance was evaluated by in vitro overexpression experiments. We found that Erava minimum inhibitory concentrations (MICs) against clinical E. faecalis isolates ranged from ≤0.015 to 0.25 mg/l even in strains harboring Tet resistance genes. The detection frequency of Erava heteroresistance in isolates with MICs ≤ 0.06, 0.125, and 0.25 mg/l were 0.43% (1/231), 7.5% (3/40), and 0 (0/5), respectively. No mutations were detected in the 30S ribosomal subunit gene in Erava heteroresistance-derived clones, although mutations in this subunit conferred cross resistance to Tige in Erava-induced resistant E. faecalis. Overexpressing RS00630 (encoding a bone morphogenetic protein family ATP-binding cassette transporter substrate-binding protein) in E. faecalis increased the frequency of Erava and Tige heteroresistance, whereas RS12140, RS06145, and RS06880 overexpression conferred heteroresistance to Tige only. These results indicate that Erava has potent in vitro antimicrobial activity against clinical E. faecalis isolates from China and that Erava heteroresistance can be induced by RS00630 overexpression.202032523563
126440.9885Characterization of mannitol-fermenting methicillin-resistant staphylococci isolated from pigs in Nigeria. This study was conducted to determine the species distribution, antimicrobial resistance pheno- and genotypes and virulence traits of mannitol-positive methicillin-resistant staphylococci (MRS) isolated from pigs in Nsukka agricultural zone, Nigeria. Twenty mannitol-positive methicillin-resistant coagulase-negative staphylococcal (MRCoNS) strains harboring the mecA gene were detected among the 64 Staphylococcus isolates from 291 pigs. A total of 4 species were identified among the MRCoNS isolates, namely, Staphylococcus sciuri (10 strains), Staphylococcus lentus (6 strains), Staphylococcus cohnii (3 strains) and Staphylococcus haemolyticus (one strain). All MRCoNS isolates were multidrug-resistant. In addition to β-lactams, the strains were resistant to fusidic acid (85%), tetracycline (75%), streptomycin (65%), ciprofloxacin (65%), and trimethoprim/sulphamethoxazole (60%). In addition to the mecA and blaZ genes, other antimicrobial resistance genes detected were tet(K), tet(M), tet(L), erm(B), erm(C), aacA-aphD, aphA3, str, dfrK, dfrG, cat pC221, and cat pC223. Thirteen isolates were found to be ciprofloxacin-resistant, and all harbored a Ser84Leu mutation within the QRDR of the GyrA protein, with 3 isolates showing 2 extra substitutions, Ser98Ile and Arg100Lys (one strain) and Glu88Asp and Asp96Thr (2 strains). A phylogenetic tree of the QRDR nucleotide sequences in the gyrA gene revealed a high nucleotide diversity, with several major clusters not associated with the bacterial species. Our study highlights the possibility of transfer of mecA and other antimicrobial resistance genes from MRCoNS to pathogenic bacteria, which is a serious public health and veterinary concern.201526413075
237850.9885Molecular Detection and Characterization of the mecA and nuc Genes From Staphylococcus Species (S. aureus, S. pseudintermedius, and S. schleiferi) Isolated From Dogs Suffering Superficial Pyoderma and Their Antimicrobial Resistance Profiles. Canine superficial pyoderma (CSP) is a bacterial infection secondary to several skin diseases of the dog. Staphylococcus pseudintermedius, which is a commensal bacterium of the dog's skin, is the leading agent found in dogs affected by CSP, which can progress to deep pyoderma. It is also of clinical significance because S. pseudintermedius strains carry antimicrobial resistance genes, mainly the mecA gene. In this descriptive longitudinal study, molecular characterization of bacterial isolates from dogs affected by CSP was performed in addition to phenotyping, antimicrobial profiling, and assessment of resistance carriage status. Fifty dogs (24 females and 26 males) attending the CES University Veterinary Teaching Hospital were included in the study. CSP was confirmed according to clinical signs and cytological examination. Swabs were taken from active skin lesions for bacterial culture, and phenotyping and antimicrobial resistance profiles were assessed using API-Staph phenotyping and the Kirby-Bauer method, respectively. We also performed molecular detection and characterization of the mecA and nuc encoding gene of coagulase-positive Staphylococci. The mecA gene frequency was established by qPCR amplification of a 131bp gene fragment. Data were evaluated by descriptive statistics. Erythema, peeling, pruritus, and alopecia were the predominant symptoms (72, 56, and 46%, respectively). We isolated bacteria compatible with Staphylococcus species from all samples tested. API phenotyping showed 83.1 to 97.8% compatibility with S. pseudintermedius. PCR-genotyping resulted in 15, 3, and 1 isolates positive for S. pseudintermedius, S. aureus, and S. schleiferi, respectively. Isolated strains showed high susceptibility to Imipenem, Ampicillin/Sulbactam, and Rifampicin (100, 94, and 92%, respectively). The highest resistance was against Vancomycin and Trimethoprim/Sulfamethoxazole (98 and 74%, respectively). S. pseudintermedius, S. aureus, and S. schleiferi isolates were cloned and shared 96% sequence homology. Finally, we found 62% carriage status of the mecA gene in isolates of CSP patients, although only 36% of the isolates were methicillin-resistant. Identification of three Staphylococcus species causing CSP, high-level resistance against conventional antimicrobials, and carriage of the mecA gene highlight the importance of performing molecular characterization of bacteria causing dermatological conditions in dogs.202032793641
238060.9885Red foxes (Vulpes vulpes) as a specific and underappreciated reservoir of resistant and virulent coagulase-positive Staphylococcus spp. strains. The aim of the study was to analyze the presence of coagulase-positive Staphylococcus in swabs collected from red foxes and to characterize the drug resistance and virulence of these bacteria. In total, 415 rectal and oral swabs were collected, and coagulase-positive strains of S. pseudintermedius (n = 104) and S. aureus (n = 27) were identified using multiplex-PCR and MALDI TOF MS. Subsequent analyses showed the highest phenotypic resistance of the strains to penicillin (16.8%) and tetracycline (30.5%) confirmed by the presence of the blaZ, tetM, and tetK genes. Slightly lower resistance to erythromycin (6.9%), clindamycin (9.2%), gentamicin, streptogramins, rifampicin, nitrofurantoin, and sulphamethoxazol/trimetophrim was exhibited by single strains. Several virulence genes in a few different combinations were detected in S. aureus; LukE-LukD, and seB were the most frequent genes (37%), LukE-LukD, seB, and seC were detected in 11% of the strains, and PVL, etA, etB, and tst genes were present in two or single strains. The results of our research have confirmed that the red fox is an underestimated reservoir of coagulase-positive Staphylococcus strains, with approximately 50% of carriers of at least one resistance gene. In turn, 88.8% of the S. aureus strains had one or more virulence genes; therefore, this species of wildlife animals should be monitored as part of epidemiological surveillance.202438113638
216970.9884E-test antibiotics susceptibility of strict anaerobic bacteria. The E-test is convenient for testing susceptibility of anaerobes. From September 1998 to September 1999, 194 strains (105 Gram-positive bacteria, 89 Gram-negative bacteria) of clinically relevant samples were tested against five antibiotics benzylpenicillin, amoxicillin-clavulanic acid, clindamycin, metronidazole and imipenem on blood agar plates. Resistance to benzyl penicillin is widespread and Gram-negative bacteria and resistance to amoxicillin-clavulanic acid is exceptional. Metronidazole is very effective against anaerobes except non-spore-forming aerotolerant Gram-positive rods and Peptostreptococcus micros.200316887712
132580.9884Antimicrobial Resistance Profiles of Bacteria Isolated from the Nasal Cavity of Camels in Samburu, Nakuru, and Isiolo Counties of Kenya. This study was designed to determine antimicrobial resistance profiles of bacteria isolated from the nasal cavity of healthy camels. A total of 255 nasal samples (swabs) were collected in Isiolo, Samburu, and Nakuru counties, Kenya, from which 404 bacterial isolates belonging to various genera and species were recovered. The bacterial isolates included Bacillus (39.60%), coagulase-negative Staphylococcus (29.95%), Streptococcus species other than Streptococcus agalactiae (25.74%), coagulase-positive Staphylococcus (3.96%), and Streptococcus agalactiae (0.74%). Isolates were most susceptible to Gentamicin (95.8%), followed by Tetracycline (90.5%), Kanamycin and Chloramphenicol (each at 85.3%), Sulphamethoxazole (84.2%), Co-trimoxazole (82.1%), Ampicillin (78.9%), and finally Streptomycin (76.8%). This translated to low resistance levels. Multidrug resistance was also reported in 30.5% of the isolates tested. Even though the antibiotic resistance demonstrated in this study is low, the observation is significant, since the few resistant normal flora could be harboring resistance genes which can be transferred to pathogenic bacteria within the animal, to other animals' bacteria and, most seriously, to human pathogens.201729147677
618390.9884Characterization of putative multidrug resistance transporters of the major facilitator-superfamily expressed in Salmonella Typhi. Multidrug resistance mediated by efflux pumps is a well-known phenomenon in infectious bacteria. Although much work has been carried out to characterize multidrug efflux pumps in Gram-negative and Gram-positive bacteria, such information is still lacking for many deadly pathogens. The aim of this study was to gain insight into the substrate specificity of previously uncharacterized transporters of Salmonella Typhi to identify their role in the development of multidrug resistance. S. Typhi genes encoding putative members of the major facilitator superfamily were cloned and expressed in the drug-hypersensitive Escherichia coli strain KAM42, and tested for transport of 25 antibacterial compounds, including representative antibiotics of various classes, antiseptics, dyes and detergents. Of the 15 tested putative transporters, STY0901, STY2458 and STY4874 exhibited a drug-resistance phenotype. Among these, STY4874 conferred resistance to at least ten of the tested antimicrobials: ciprofloxacin, norfloxacin, levofloxacin, kanamycin, streptomycin, gentamycin, nalidixic acid, chloramphenicol, ethidium bromide, and acriflavine, including fluoroquinolone antibiotics, which were drugs of choice to treat S. Typhi infections. Cell-based functional studies using ethidium bromide and acriflavine showed that STY4874 functions as a H(+)-dependent exporter. These results suggest that STY4874 may be an important drug target, which can now be tested by studying the susceptibility of a STY4874-deficient S. Typhi strain to antimicrobials.201525724589
2446100.9884Low selection of topoisomerase mutants from strains of Escherichia coli harbouring plasmid-borne qnr genes. OBJECTIVES: To investigate mutations in the type II topoisomerase genes in quinolone-resistant mutants selected from bacteria harbouring plasmid-borne qnr genes. METHODS: Mutants were selected by nalidixic acid, ciprofloxacin and moxifloxacin from two Escherichia coli reference strains and corresponding transconjugants harbouring qnrA1, qnrA3, qnrB2 or qnrS1 genes. RESULTS: The proportion of resistant mutants selected by the three quinolones was, respectively, in the same range for qnr-positive transconjugants and reference strains. Only 20% (65/329) of the mutants selected from the transconjugants showed a gyrase mutation, whereas 79% (94/119) of those from the reference strains without a qnr gene did (P < 0.0001). At four times the MIC of the selector quinolone, gyrA mutants represented 49% and 95% of the mutants selected with nalidixic acid, 4% and 94% with ciprofloxacin and 0% and 54% with moxifloxacin for qnr-positive transconjugants and reference strains, respectively. Mutations within gyrA were distributed at codon 87 (D87G, H, N or Y) and at codon 83 (S83L) with three novel mutations (gyrA Ser83stop, gyrA Asp82Asn and gyrB insertion of Glu at 465) and three rare mutations (gyrA Gly81Asp, gyrA Asp82Gly and gyrA Ser431Pro), mainly obtained from reference strains after moxifloxacin selection. Strikingly, none of the mutants selected by moxifloxacin from qnr-positive transconjugants harboured a mutation in the topoisomerase genes. CONCLUSIONS: Topoisomerase mutants are rarely selected by ciprofloxacin and moxifloxacin from strains harbouring qnr. This suggests that the quinolone resistance-determining region domains are protected from quinolones by the Qnr protein and consequently other mechanisms are developed to acquire a further step of fluoroquinolone resistance.200818325893
1263110.9884Antimicrobial Resistance and Antimicrobial Activity of Staphylococcus lugdunensis Obtained from Two Spanish Hospitals. Staphylococcus lugdunensis is a coagulase-negative-staphylococci (CoNS) that lately has gained special attention in public health as a human pathogen and also as a bacteriocin-producer bacteria. In this study, we characterized 56 S. lugdunensis isolates recovered from human samples in two Spanish hospitals. Antimicrobial susceptibility testing was performed and antimicrobial resistance and virulence genotypes were determined. Antimicrobial activity (AA) production was evaluated by the spot-on-lawn method against 37 indicator bacteria, including multidrug-resistant (MDR) isolates, and the presence of the lugD gene coding for lugdunin bacteriocin was analyzed by PCR. The antibiotic resistance detected was as follows (% resistance/genes detected): penicillin (44.6%/blaZ), oxacillin (1.8%/mecA on SCCmec-V), erythromycin-clindamycin inducible (7.1%/erm(C), msrA), tetracycline (5.3%/tetK), gentamicin and/or tobramycin (3.6%/ant(4')-Ia, acc(6')-aph(2″)), and fosfomycin (21.4%). A MDR phenotype was detected in 5% of isolates. Twenty-one of the S. lugdunensis isolates showed susceptibility to all 20 antibiotics tested (37.5%). The screening for AA revealed 23 antimicrobial producer (AP) isolates with relevant inhibition against coagulase-positive-staphylococci (CoPS), including both methicillin-susceptible and -resistant S. aureus. The lugD gene was detected in 84% of the 56 S. lugdunensis isolates. All of the AP S. lugdunensis isolates (n = 23) carried the lugD gene and it was also detected in 24 of the non-AP isolates, suggesting different gene expression levels. One of the AP isolates stood out due to its high antimicrobial activity against more than 70% of the indicator bacteria tested, so it will be further characterized at genomic and proteomic level.202235893538
1265120.9884Coagulase-negative staphylococci (CoNS) isolated from ready-to-eat food of animal origin--phenotypic and genotypic antibiotic resistance. The aim of this work was to study the pheno- and genotypical antimicrobial resistance profile of coagulase negative staphylococci (CoNS) isolated from 146 ready-to-eat food of animal origin (cheeses, cured meats, sausages, smoked fishes). 58 strains were isolated, they were classified as Staphylococcus xylosus (n = 29), Staphylococcus epidermidis (n = 16); Staphylococcus lentus (n = 7); Staphylococcus saprophyticus (n = 4); Staphylococcus hyicus (n = 1) and Staphylococcus simulans (n = 1) by phenotypic and genotypic methods. Isolates were tested for resistance to erythromycin, clindamycin, gentamicin, cefoxitin, norfloxacin, ciprofloxacin, tetracycline, tigecycline, rifampicin, nitrofurantoin, linezolid, trimetoprim, sulphamethoxazole/trimethoprim, chloramphenicol, quinupristin/dalfopristin by the disk diffusion method. PCR was used for the detection of antibiotic resistance genes encoding: methicillin resistance--mecA; macrolide resistance--erm(A), erm(B), erm(C), mrs(A/B); efflux proteins tet(K) and tet(L) and ribosomal protection proteins tet(M). For all the tet(M)-positive isolates the presence of conjugative transposons of the Tn916-Tn1545 family was determined. Most of the isolates were resistant to cefoxitin (41.3%) followed by clindamycin (36.2%), tigecycline (24.1%), rifampicin (17.2%) and erythromycin (13.8%). 32.2% staphylococcal isolates were multidrug resistant (MDR). All methicillin resistant staphylococci harboured mecA gene. Isolates, phenotypic resistant to tetracycline, harboured at least one tetracycline resistance determinant on which tet(M) was most frequent. All of the isolates positive for tet(M) genes were positive for the Tn916-Tn1545 -like integrase family gene. In the erythromycin-resistant isolates, the macrolide resistance genes erm(C) or msr(A/B) were present. Although coagulase-negative staphylococci are not classical food poisoning bacteria, its presence in food could be of public health significance due to the possible spread of antibiotic resistance.201525475289
2293130.9884Mechanisms of Resistance in Clinical Isolates of Enterobacter cloacae that Are Less Susceptible to Cefepime than to Ceftazidime. Thirty-two Enterobacter cloacae strains that are less susceptible to cefepime than to ceftazidime were collected. This unique phenotype of 8 strains was confirmed using the agar dilution method. OXA1, OXA10, OXA31 and OXA35 were detected in 3, 2, 3, and 2 strains, respectively, whereas all strains were negative for PSE-1 genes. OXA genes were also identified in the plasmid DNA of 5 strains, but only 2 strains were positive in a conjugation experiment. The acrA, acrB and tolC genes were identified in 4, 4 and 6 strains, respectively. Decreased expression of the acrA mRNA and overexpression of the acrB and tolC mRNAs were observed using real-time RT-PCR. Most of the bacteria (n=7) stably expressed the marA gene, which is a regulatory gene in the AcrAB-TolC multidrug efflux system, whereas all strains were negative for ramA. The acrA, acrB, tolC, acrR and marA genes were similar to the genes in reference strains in GenBank, with nucleotide homologies of 96%, 98%, 98%, 98% and 100%, respectively. In conclusion, the mechanism of resistance of Enterobacter cloacae with less susceptibility to cefepime than to ceftazidime is associated with the overexpression of AcrAB-TolC and the production of OXA1, XA10, OXA31 and OXA35.201829970440
407140.9884Molecular cloning and characterization of two lincomycin-resistance genes, lmrA and lmrB, from Streptomyces lincolnensis 78-11. Two different lincomycin-resistance determinants (lmrA and lmrB) from Streptomyces lincolnensis 78-11 were cloned in Streptomyces lividans 66 TK23. The gene lmrA was localized on a 2.16 kb fragment, the determined nucleotide sequence of which encoded a single open reading frame 1446 bp long. Analysis of the deduced amino acid sequence suggested the presence of 12 membrane-spanning domains and showed significant similarities to the methylenomycin-resistance protein (Mmr) from Streptomyces coelicolor, the QacA protein from Staphylococcus aureus, and several tetracycline-resistance proteins from both Gram-positive and Gram-negative bacteria, as well as to some sugar-transport proteins from Escherichia coli. The lmrB gene was actively expressed from a 2.7 kb fragment. An open reading frame of 837 bp could be localized which encoded a protein that was significantly similar to 23S rRNA adenine(2058)-N-methyltransferases conferring macrolide-lincosamide-streptogramin resistance. LmrB also had putative rRNA methyltransferase activity since lincomycin resistance of ribosomes was induced in lmrB-containing strains. Surprisingly, both enzymes, LmrA and LmrB, had a substrate specificity restricted to lincomycin and did not cause resistance to other lincosamides such as celesticetin and clindamycin, or to macrolides.19921328813
5940150.9884In vitro activities of spectinomycin and comparator agents against Pasteurella multocida and Mannheimia haemolytica from respiratory tract infections of cattle. OBJECTIVES: Prior to the renewal of spectinomycin licensing for veterinary uses in Germany, 154 Pasteurella multocida and 148 Mannheimia haemolytica strains from respiratory tract infections in cattle were investigated for their MICs of spectinomycin and other antimicrobial agents. The data obtained should serve as a baseline from which to judge the future development of resistance. Moreover, the in vitro activity of spectinomycin in comparison with other antimicrobials should be assessed. METHODS: MIC determination for all 302 strains was performed by the broth dilution method and evaluated according to NCCLS standards. MIC(50) and MIC(90) values were calculated. Strains resistant to spectinomycin were subjected to PCR assays for genes known to mediate spectinomycin resistance in Gram-negative and Gram-positive bacteria. RESULTS: With the exception of resistance to sulfamethoxazole in P. multocida and M. haemolytica, and resistance to ampicillin in M. haemolytica, an overall low level of resistance was detected. A total of 93.5% of the P. multocida and 98.6% of the M. haemolytica strains were susceptible to spectinomycin, with MIC(90)s of 32 mg/L. PCR analysis showed that none of the spectinomycin-resistant strains carried any of the aadA gene subtypes, nor the genes spc or aad(9). CONCLUSIONS: Prior to the renewal of spectinomycin, only a small number of spectinomycin-resistant strains was detected among bovine P. multocida and M. haemolytica. The genes responsible for spectinomycin resistance in these strains seemed to be different from those so far known to occur in other Gram-negative and Gram-positive bacteria.200414729757
5387160.9884Assessment of antibiotic susceptibility within lactic acid bacteria strains isolated from wine. Susceptibility to 12 antibiotics was tested in 75 unrelated lactic acid bacteria strains of wine origin of the following species: 38 Lactobacillus plantarum, 3 Lactobacillus hilgardii, 2 Lactobacillus paracasei, 1 Lactobacillus sp, 21 Oenococcus oeni, 4 Pediococcus pentosaceus, 2 Pediococcus parvulus, 1 Pediococcus acidilactici, and 3 Leuconostoc mesenteroides. The Minimal Inhibitory Concentrations of the different antibiotics that inhibited 50% of the strains of the Lactobacillus, Leuconostoc and Pediococcus genera were, respectively, the following ones: penicillin (2, < or =0.5, and < or =0.5 microg/ml), erythromycin (< or =0.5 microg/ml), chloramphenicol (4 microg/ml), ciprofloxacin (64, 8, and 128 microg/ml), vancomycin (> or =128 microg/ml), tetracycline (8, 2, and 8 microg/ml), streptomycin (256, 32, and 512 microg/ml), gentamicin (64, 4, and 128 microg/ml), kanamycin (256, 64, and 512 microg/ml), sulfamethoxazole (> or =1024 microg/ml), and trimethoprim (16 microg/ml). All 21 O. oeni showed susceptibility to erythromycin, tetracycline, rifampicin and chloramphenicol, and exhibited resistance to aminoglycosides, vancomycin, sulfamethoxazole and trimethoprim, that could represent intrinsic resistance. Differences were observed among the O. oeni strains with respect to penicillin or ciprofloxacin susceptibility. Antibiotic resistance genes were studied by PCR and sequencing, and the following genes were detected: erm(B) (one P. acidilactici), tet(M) (one L. plantarum), tet(L) (one P. parvulus), aac(6')-aph(2") (four L. plantarum, one P. parvulus, one P. pentosaceus and two O. oeni), ant(6) (one L. plantarum, and two P. parvulus), and aph(3')-IIIa (one L. plantarum and one O. oeni). This is the first time, to our knowledge, that ant(6), aph(3')-IIIa and tet(L) genes are found in Lactobacillus and Pediococcus strains and antimicrobial resistance genes are reported in O. oeni strains.200616876896
5377170.9883Synthetic lincosamides iboxamycin and cresomycin are active against ocular multidrug-resistant methicillin-resistant Staphylococcus aureus carrying erm genes. OBJECTIVE: Antimicrobial resistance is a global pandemic that poses a major threat to vision health as ocular bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), are becoming increasingly resistant to first-line therapies. Here we evaluated the antimicrobial activity of new synthetic lincosamides in comparison to currently used antibiotics against clinical ocular MRSA isolates. METHODS: Antimicrobial susceptibility testing was performed by broth microdilution for two novel synthetic lincosamides (iboxamycin and cresomycin) and eight comparator antibiotics against a collection of 50 genomically characterised ocular MRSA isolates, including isolates harbouring erm genes (n = 25). RESULTS: Both drugs were active against widespread MRSA clonal complexes CC8 and CC5. The MIC(50) and MIC(90) of iboxamycin were 0.06 and 2 mg/L, respectively. Cresomycin (MIC(50) = 0.06 mg/L) also displayed good activity with an in vitro potency four-fold higher (MIC(90) = 0.5 mg/L) than iboxamycin. In isolates harbouring erm genes, MIC(90) were >16, 2, and 0.5 mg/L for clindamycin, iboxamycin, and cresomycin, respectively. The in vitro potencies of iboxamycin and cresomycin were similar or higher than that of comparator agents and were not impacted by multidrug-resistance phenotypes or by the presence of erm genes when compared with clindamycin. CONCLUSIONS: Our results demonstrate that iboxamycin and cresomycin display potent in vitro activity against ocular MRSA isolates, including multidrug-resistant isolates harbouring erm genes.202439293511
5849180.9882Characterisation and molecular cloning of the novel macrolide-streptogramin B resistance determinant from Staphylococcus epidermidis. A total of 110 staphylococcal isolates from human skin were found to express a novel type of erythromycin resistance. The bacteria were resistant to 14-membered ring macrolides (MIC 32-128 mg/l) but were sensitive to 16-membered ring macrolides and lincosamides. Resistance to type B streptogramins was inducible by erythromycin. A similar phenotype, designated MS resistance, was previously described in clinical isolates of coagulase-negative staphylococci from the USA. In the UK, MS resistance is widely distributed in coagulase-negative staphylococci but was not detected in 100 erythromycin resistant clinical isolates of Staphylococcus aureus. Tests for susceptibility to a further 16 antibiotics failed to reveal any other selectable marker associated with the MS phenotype. Plasmid pattern analysis of 48 MS isolates showed considerable variability between strains and no common locus for the resistance determinant. In one strain of S. epidermidis co-resistance to tetracycline, penicillin and erythromycin (MS) was associated with a 31.5 kb plasmid, pUL5050 which replicated and expressed all three resistances when transformed into S. aureus RN4220. The MS resistance determinant was localised to a 1.9 kb fragment which was cloned on to the high-copy-number vector, pSK265. A constitutive mutant of S. aureus RN4220 containing the 1.9 kb fragment remained sensitive to clindamycin. This observation, together with the concentration-dependent induction (optimum 5 mg/l of erythromycin) of virginiamycin S resistance suggests that the MS phenotype is not due to altered expression of MLS resistance determinants (erm genes) but probably occurs via a different mechanism.19892559912
5234190.9882A Multidrug-Resistant Escherichia coli Caused the Death of the Chinese Soft-Shelled Turtle (Pelodiscus sinensis). The rapid increase in drug resistance in recent years has become a significant global public health concern. Escherichia coli are ubiquitous bacteria, widely distributed in various environments. This study isolated a bacterial strain (HD-593) from diseased Chinese soft-shelled turtles (Pelodiscus sinensis). The bacterium was identified based on morphology, biochemical tests, and 16S rRNA sequencing, confirming it as E. coli. Drug susceptibility tests revealed that the HD-593 strain was highly resistant to ceftriaxone, enrofloxacin, doxycycline, sulfadiazine, gentamicin, neomycin, florfenicol, carbenicillin, cefradine, erythromycin, penicillin, ampicillin, midecamycin, and streptomycin. Resistance gene analysis confirmed the presence of quinolone resistance genes (oqxA and oqxB), aminoglycoside resistance genes (aac(3)-II and aphA1), a β-lactam resistance gene (blaTEM), and an acylaminol resistance gene (floR) in HD-593. The median lethal dose (LD50) of HD-593 for P. sinensis was 6.53 × 10(5) CFU/g. Biochemical analysis of serum revealed that HD-593 infection caused a significant reduction in total protein, albumin, and globulin levels, while markedly increasing the levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Histopathological analysis revealed severe intestinal damage characterized by villi detachment and muscle cell necrosis. Additionally, extensive splenocyte necrosis with nuclear marginalization, glomerular swelling, and pronounced hepatic steatosis accompanied by distended sinusoids were observed. This study identified a multidrug-resistant E. coli strain from deceased P. sinensis, suggesting that drug resistance genes may circulate in aquaculture ecosystems, posing potential risks to aquaculture.202540431566