Isolation and Analysis of Bacteria with Antimicrobial Activities from the Marine Sponge Haliclona simulans Collected from Irish Waters

Samples of the marine sponge Haliclona simulans were collected from Irish coastal waters, and bacteria were isolated from these samples. Phylogenetic analyses of the cultured isolates showed that four different bacterial phyla were represented; Bacteriodetes, Actinobacteria, Proteobacteria, and Firmicutes. The sponge bacterial isolates were assayed for the production of antimicrobial substances, and biological activities against Gram-positive and Gram-negative bacteria and fungi were demonstrated, with 50% of isolates showing antimicrobial activity against at least one of the test strains. Further testing showed that the antimicrobial activities extended to the important pathogens Pseudomonas aeruginosa, Clostridium difficile, multi-drug-resistant Staphylococcus aureus, and pathogenic yeast strains. The Actinomycetes were numerically the most abundant producers of antimicrobial activities, although activities were also noted from Bacilli and Pseudovibrio isolates. Surveys for the presence of potential antibiotic encoding polyketide synthase and nonribosomal peptide synthetase genes also revealed that genes for the biosynthesis of these secondary metabolites were present in most bacterial phyla but were particularly prevalent among the Actinobacteria and Proteobacteria. This study demonstrates that the culturable fraction of bacteria from the sponge H. simulans is diverse and appears to possess much potential as a source for the discovery of new medically relevant biological active agents.     

The antimicrobial effects of propolis collected in different regions in the Basque Country (Northern Spain)

The antimicrobial activity of 19 propolis extracts prepared in different solvents (ethanol and propylene glycol) (EEP/PEP), was evaluated against some bacterial and fungal isolates using the agar-well diffusion method. It was verified that all the samples tested showed antimicrobial activity, although results varied considerably between samples. Results revealed that both types of propolis extracts showed highly sensitive antimicrobial action against Gram-positive bacteria and fungi at a concentration of 20% (Staphylococcus aureus, Streptococcus mutans, Candida albicans and Saccharomyces cerevisae) with a minimal inhibitory concentration (MIC) ranging from 0.5 to 1.5 mg/ml, with a moderate effect against Streptococcus pyogenes (MIC from 17 to 26 mg/ml). To our knowledge, this is the first study showing elevated antimicrobial activity against Gram-negative bacteria [Salmonella enterica (MIC from 0.6 to 1.4 mg/ml)] and lesser activity against Helicobacter pylori (MIC from 6 to 14 mg/ml), while Escherichia coli was resistant. This concluded that the Basque propolis had a strong and dose-dependent activity against most of the microbial strains tested, while database comparison revealed that phenolic substances were responsible for this inhibition, regardless of their geographical origin and the solvent employed for extraction. Statistical analysis showed no significant differences (P ≤ 0.05) between EEP and PEP extracts.     

High antimicrobial resistance among bacterial isolates of blood stream infections (BSI) in a Nigerian University Teaching Hospital

The antimicrobial resistance profile of 220 bacteria isolated from 1,006 episodes of blood stream infections (BSI) between January 2004 and December 2005 in a University Teaching Hospital, Southwestern Nigeria, were analyzed. Gram positive bacteria constituted 47.3% while Gram negative constituted 52.7%. The most common organisms were Staphylococcus aureus (37.3%), Klebsiella (30%), Pseudomonas (8.2%), Proteus (6.4%), Escherichia coli (5.5%) and coagulase negative staphylococci (4.6%). The cumulative resistance of all the bacteria isolates to ampicillin was 79%, gentamicin 51%, ceftazidime 11% and ciprofloxacin 6%. About 85% of the Gram positive bacteria were resistant to penicillinG, 79% to methicillin and 37% to erythromycin while 74% of the Gram negative bacteria were resistant to cotrimoxazole, 69% to tetracycline and 38% to chloramphenicol. Among the 7 antibiotics tested for each group, 7 patterns of antibiotic resistance were observed for each; 6 were multi-drug pattern with number of antibiotics ranging from 2 to 7. This study demonstrates high antimicrobial resistance among clinical bacterial isolates of BSI to commonly prescribed antibiotics most especially penicillinG, ampicillin, methicillin, cotrimoxazole, tetracycline and gentamicin. Based on the result of this study, it is suggested that the combination of ampicillin and gentamicin normally employed for empirical treatment of BSI in our hospital should be stopped.     

Multivariate analysis to discriminate yeast strains with technological applications in table olive processing

This survey uses a multivariate classification analysis to discriminate yeast strains with interesting biochemical activities for the processing of table olives among a collection of 32 isolates belonging to 16 different yeast species. Lipase, esterase and β-glucosidase activities (desirable characteristics) were quantitatively evaluated in both extracellular and cellular fractions for all isolates in different types of culture media. The study of the quantitative data by cluster and principal component analyses led to the identification of several Wickerhamomyces anomalus, Candida boidinii and Candida diddensiae isolates with promising characteristics (the best global activity levels), clearly differentiated from the rest of the yeasts. The results obtained in this work open up new alternatives to this methodology for the study, classification and selection of the most suitable yeasts to be used as starters, alone or in combination with lactic acid bacteria, during table olive processing.     

Antimicrobial susceptibility recording and reporting system for veterinary medicine

Objectives: To develop a system to (1) provide automated interpretation of antimicrobial susceptibility results using animal species, specimen site and bacterial isolate identification criteria, (2) report antimicrobial susceptibility results, according to recommended use category and animal species approval status, (3) allow for changes in antimicrobial agent being tested and result interpretations without need for programming changes and (4) allow for intuitive data entry process without need for reference material. Design: Tables are used to match results and reporting categories to a test method, specific tests, animal species, specimen sites and bacterial isolates. Information used for interpretation of test readings is maintained in tables for user reference while entering results. Results: A table driven system was developed to account for variations in reporting due to antimicrobial susceptibility method used, animal species, bacterial isolate tested and the site from which bacteria isolate was recovered. Conclusions: This process provides for accurate reporting of antimicrobial susceptibility results and is easily adaptable to changes in reporting requirements. The system minimizes reporting criteria and decision-making requirements for technical laboratory personnel, while improving antimicrobial susceptibility reports generated for veterinary practitioners.     

Isolation and screening of brittlestar-associated bacteria for antibacterial activity

Many microbes associated with marine organisms have antimicrobial activity. We report the isolation of bacteria associated with Amphipholis gracillima that have broad-spectrum antibacterial activity against a number of common bacterial strains. Fifty-eight isolates of bacilli obtained from A. gracillima arm homogenates, from excised wound tissue, or from swabs of arm stumps exhibited 20–100% inhibition of one or more of 16 test bacteria at 35% salinity. Forty-one of the isolates were capable of 20–100% inhibition of one or more of 19 subject bacteria at 10% salinity at 37°C. Three isolates, BE37, BE52, and BE53, exhibited the greatest range of antibacterial activity at both 10% and 35% salinity. Our results suggest that some of the bacteria associated with A. gracillima may provide the animal with chemical defenses against adverse bacterial infection. The water-soluble inhibitory chemicals produced by the bacteria could potentially function as antimicrobial compounds against human pathogenic bacteria. Received: 30 July 2001 / Accepted: 15 October 2001     

Activity of the Antimicrobial Peptide and Thanatin Analog S-thanatin on Clinical Isolates of <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> Resistant to Conventional Antibiotics with Different Structures

The treatment of infections caused by bacteria resistant to the vast majority of antibiotics is a challenge worldwide. To evaluate the effect of S-thanatin (an analog of thanatin, a cationic antimicrobial peptide isolated from the hemipteran insect Podisus maculiventris) against microbial resistant to antibiotics, we studied its bactericidal kinetics, synergistic effect, resistance, and activity on clinical isolates of Klebsiella pneumoniae resistant to conventional antibiotics with different structures. The bactericidal rate of S-thanatin was more than 99% against K. pneumoniae ATCC 700603 when bacterial cultures were monitored for 60 min. The peptide was synergistic with β-lactam cefepime in most of the clinical MDR isolates tested (7/8). An average value of FIC was 0.3708. No synergy was found between the peptide and amoxicillin, gentamycin, tetracycline, or ciprofloxacin in all bacteria tested. A total of 48 isolates of K. pneumoniae with different resistance spectrum tested was susceptible to S-thanatin. The MICs were 6.25–25 μg/ml. No significant difference in the MICs of S-thanatin between the sensitive isolates and the resistant isolates to single antibiotic was observed (P > 0.05). The resistance of K. pneumoniae ATCC 700603 to S-thanatin was slightly higher, when cultured at sub-inhibitory concentration for 5 days. S-thanatin may be an attractive candidate for developing into an antimicrobial agent.     

Microbial communities associated with the root system of wild olives (Olea europaea L. subsp. europaea var. sylvestris) are good reservoirs of bacteria with antagonistic potential against Verticillium dahliae

Wild olive trees, namely oleaster, are considered the ancestor of cultivated olive and a unexplored source of genetic variability that might contain important traits of agronomic and biotechnological interest. The longevity and genetic diversity of oleasters may have favoured selection of specific and well adapted rhizosphere microbial populations that can constitute unique reservoirs of microbial antagonists of Verticillium dahliae, the main soilborne fungal pathogen of olive worldwide. The objective of this present study was to determine the structure and diversity of bacterial communities in the rhizosphere and endosphere of oleaster from 11 havens in Cádiz and Córdoba provinces of Andalusia, southern Spain. To carry out the study we used a multiphasic approach. First, the occurrence and diversity of rhizosphere bacteria was monitored by a cultivation-independent-approach, using fluorescent terminal restriction fragment length polymorphism (FT-RFLP) analyses of amplified 16S rDNA sequences. FT-RFLP patterns revealed a high heterogeneity in the composition of the sampled rhizosphere bacterial communities and suggested the existence of plant genotype-site-specific communities, with each oleaster haven being a unique reservoir of bacterial diversity. Secondly, to investigate the antagonistic potential of these root-associated bacterial populations, a total of 675 bacterial isolates obtained from oleaster rhizosphere and endosphere were screened by dual testing for inhibition of in vitro growth of the highly virulent, olive defoliating pathotype of V. dahliae. Out of 675 tested bacterial isolates, 94 (14%) showed a strong antagonistic activity against a defoliating V. dahliae pathotype. Of the antagonistic bacteria, a slightly lower proportion (12.9% of total bacteria) were inhabitant of the oleaster rhizosphere compared to that in the endosphere (16.5%). The biotechnological potential of those isolates was assessed by in vitro production of different hydrolytic enzymes, indole-1.3-acetic acid (IAA), siderophores, and antimicrobial compounds. Overall, most of bacterial antagonists (58.5 to 78.3%) showed proteolytic, lipolytic, and chitinolytic activity, and produced IAA and siderophores. Finally, analysis of the 16S rDNA gene sequence indicated that most of the 94 bacterial antagonists belong to genera Bacillus (56.4%), Pseudomonas (27.7%), and Paenibacillus (7.4%). Overall, the rhizosphere and endosphere of wild olives were proved as a good reservoir of bacteria antagonists against V. dahliae. Several of those bacteria showing high and broad antagonism potential may therefore be considered for further analyses as promising biocontrol agents against V. dahliae in olive.     

Abundance and Bioactivity of Cultured Sponge-Associated Bacteria from the Mediterranean Sea

In this study, the search for new antibiotics was combined with quantitative ecological studies. The cultured fraction of the associated bacterial communities from ten different Mediterranean sponge species was investigated. To obtain quantitative and qualitative data of sponge-associated bacterial communities and to expand the cultured diversity, different media were used. The largest morphological diversity and highest yield of isolates was obtained by using oligotrophic media, which consisted of natural habitat seawater amended with (1% additional carbon sources. The dominant bacterial morphotypes were determined and bacterial isolates were tested for antimicrobial activity and identified using 16S rDNA sequencing. The sponge-associated most abundant morphotypes were all affiliated to the Alphaproteobacteria and showed antimicrobial activity against at least one of the tested strains. In contrast, the ambient seawater was dominated by Gammaproteobacteria. One single alphaproteobacterium, which was related to Pseudovibrio denitrificans, was shown to dominate the cultured community of at least six of the sponges. This designated MBIC3368-like alphaproteobacterium has been isolated from sponges before and seems to be restricted to associations with members of the phylum Porifera. It displays a weak and unstable antimicrobial activity, which gets easily lost during cultivation. However, this bioactive bacterium was present in the sponges by up to 10⁶ cells per gram wet-weight sponge tissue and dominated the cultured fraction with up to 74%. The association of this alphaproteobacterium with sponges is probably evolutionary young and facultative and possibly involves biologically active secondary metabolites. Besides a demonstrated vertical transfer, additional horizontal transfer between the sponges is assumed. Members of the genus Bacillus displaying antimicrobial activity were found regularly, too. However, actinomycetes, which are known for their production of bioactive substances, were present in very low abundance.     

Effect of Carbon Source on the Antimicrobial Activity of the Air Flora

Summary In an attempt to screen for air flora producing new potent antimicrobial substances, Bacillus megaterium NB-3, Bacillus cereus NB-4, Bacillus cereus NB-5, Bacillus subtilis NB-6 and Bacillus circulans NB-7, were isolated and were found to be antagonistic to bacteria and/or fungi. Production of antimicrobial substances by the bacterial strains was greatly influenced by variation of carbon sources. Glycerol strongly enhanced the antimicrobial activity of strains NB-3 and NB-6, whereas glucose increased the antimicrobial activity of strains NB-4 and NB-5. The maximum antibiotic yield of NB-7 was achieved with fructose as a carbon source. Starch (Bacillus megaterium NB-3), maltose (Bacillus cereus NB-5), glycerol (Bacillus circulans NB-7), arabinose, ribose (Bacillus cereus NB-4) and arabinose, fructose, glucose, ribose and sucrose (Bacillus subtilis NB-6) repressed the production of antimicrobial substances by the respective bacterial strains.     

一株肠膜明串珠菌的分离鉴定及其抑菌特性

[背景] 水产病原细菌严重威胁水产动物健康且制约水产养殖业发展,细菌性鱼病的有效防治成为水产养殖领域亟待解决的问题。[目的] 筛选对水产病原细菌有抑制效果的菌株,并研究其抑菌特性及其在水产细菌病害防治中的实际效果。[方法] 通过16S rRNA基因测序、构建系统发育树和生理生化鉴定确定筛选菌株的进化地位,通过乙酸乙酯萃取获得抑菌物质粗提物,通过偶氮酪蛋白法检测菌株胞外蛋白酶活力,采用结晶紫染色法对菌株的生物膜形成能力进行测定,通过浸浴攻毒模型确定所筛菌株对维氏气单胞菌的防治作用。[结果] 从泡菜发酵物中筛选出一株乳酸菌DH,经16S rRNA基因测序、发育树分析和生理生化鉴定确定其为肠膜明串珠菌,该菌分泌的胞外抑菌物质对鼠伤寒沙门氏菌、大肠埃希氏菌、铜绿假单胞菌、杀鲑气单胞菌、希瓦氏菌和维氏气单胞菌表现出抑菌效果,其抑菌物质能被乙酸乙酯萃取并且具有热稳定性。菌株DH能够显著抑制待测菌株的蛋白酶产量和生物膜形成能力,并且对维氏气单胞菌浸浴攻毒有防治作用。[结论] 肠膜明串珠菌DH通过分泌抑菌物质抑制水产病原细菌的生长,能够为细菌性鱼病的防治提供一定的理论和应用潜力。     

Microbial survey of shared-use cosmetic test kits available to the public

Summary Some people like to try cosmetics before purchasing them. With repeated use by different customers, however, the tester kits provided by many retail outlets can become potential vectors of microbial pathogens. A survey was conducted to assess the health risk from bacteria found on shared-use cosmetics. A total of 3027 shared-use cosmetic product samples were collected from 171 retail establishments throughout the contiguous United States. Eye, face and lip cosmetics were tested within situ nondestructive swabbing and the use of the Transette 3R Modified Amies Charcoal Culture and Transport System. Bacteria were isolated from about 50% of the items for all three categories. Semiquantitatively-estimated mean densities were 2288, 1685 and 1088 CFU g^–1 for eye, face and lip products, respectively. Ranges for all categories were 0–15⁵ CFU g^–1. About 5% of the items had bacterial counts above 5000 CFU g^–1 (eye products) or 10 000 CFU g^–1 (other products). More than 60% of isolates were typical of microflora from human skin; the remainder were environmental microbes. About 60% of the isolates were Gram-positive cocci:Staphylococcus spp. (especiallyS. epidermidis) andMicrococcus spp. The Gram-negative pathogenPseudomonas aeruginosa constituted 0.07% of the isolates. The survey results suggest that the preservation systems of some of the cosmetics failed under excessive use (abuse), and indicated a potential for microbiological safety problems with shared-use consmetics.     

Isolation and molecular characterization of multidrug-resistant Gram-negative bacteria from imported flamingos in Japan

Imported animals, especially those from developing countries, may constitute a potential hazard to native animals and to public health. In this study, a new flock of lesser flamingos imported from Tanzania to Hiroshima Zoological Park were screened for multidrug-resistant Gram-negative bacteria, integrons and antimicrobial resistance genes. Thirty-seven Gram-negative bacterial isolates were obtained from the flamingos. Seven isolates (18.9%) showed multidrug resistance phenotypes, the most common being against: ampicillin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole and nalidixic acid. Molecular analyses identified class 1 and class 2 integrons, β-lactamase-encoding genes, bla _TEM-1 and bla _CTX-M-2 and the plasmid-mediated quinolone resistance genes, qnrS and qnrB. This study highlights the role of animal importation in the dissemination of multidrug-resistant bacteria, integrons and antimicrobial resistance genes from one country to another.     

Survey of Shiga toxigenic Escherichia coli O157 and drug-resistant coliform bacteria from in-line milk filters on dairy farms in the Czech Republic

Aims: To determine the occurrence of Shiga toxin‐producing Escherichia coli (STEC) O157 and coliform bacteria isolates resistant to antimicrobial agents in dairy herds by examining milk filters and to analyse the influence of management factors and antibiotic use on antimicrobial resistance. Methods and Results: A total of 192 in‐line milk filters were sampled on 192 dairy farms in the Czech Republic. Information on feeding, husbandry, production, and antibiotic therapy were obtained by questionnaire. The milk filters were cultured for STEC O157 and coliform bacteria. All recovered isolates were examined for antimicrobial susceptibility and presence of antimicrobial‐resistance genes. STEC O157 was detected in four (2%) of the filters. Resistant nonpathogenic E. coli and coliform bacteria isolates with specific genes were detected in 44 (23%) of the filters. Conclusions: The study demonstrated a high prevalence of resistant coliform bacteria in milk filters obtained on Czech dairy farms. Significance and Impact of the Study: The occurrence of resistant coliform bacteria in milk filters was significantly higher among isolates from farms where antibiotic therapy against mastitis was employed during the dry period (P < 0·05).     

Phylogenetic and Physiological Diversity of Bacteria Isolated from Puruogangri Ice Core

The microbial abundance, the percentage of viable bacteria, and the diversity of bacterial isolates from different regions of a 83.45-m ice core from the Puruogangri glacier on the Tibetan Plateau (China) have been investigated. Small subunit 16S rRNA sequences and phylogenetic relationships have been studied for 108 bacterial isolates recovered under aerobic growth conditions from different regions of the ice core. The genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-polymerase chain reaction and physiological heterogeneity of the closely evolutionary related bacterial strains isolated from different ice core depths were analyzed as well. The results showed that the total microbial cell, percentages of live cells, and the bacterial CFU ranged from 10⁴ to 10⁵ cell ml⁻¹ (Mean, 9.47 × 10⁴; SD, 5.7 × 10⁴, n = 20), 25–81%, and 0–760 cfu ml⁻¹, respectively. The majority of the isolates had 16S rRNA sequences similar to previously determined sequences, ranging from 92 to 99% identical to database sequences. Based on their 16S rRNA sequences, 42.6% of the isolates were high-G + C-content (HGC) gram-positive bacteria, 35.2% were low-G + C (LGC) gram-positive bacteria, 16.6% were Proteobacteria, and 5.6% were CFB group. There were clear differences in the depth distribution of the bacterial isolates. The isolates tested exhibited unique phenotypic properties and high genetic heterogeneity, which showed no clear correlation with depths of bacterial isolation. This layered distribution and high heterogeneity of bacterial isolates presumably reflect the diverse bacterial sources and the differences in bacteria inhabiting the glacier’s surface under different past climate conditions.     

Lantibiotics biosynthesis genes and bacteriocinogenic activity of <Emphasis Type="Italic">Lactobacillus</Emphasis> spp. isolated from raw milk and cheese

Lactobacillus species are usually used as starters for the production of fermented products, and some strains are capable of producing antimicrobial substances, such as bacteriocins. Because these characteristics are highly desirable, research are continually being performed for novel Lactobacillus strains with bacteriocinogenic potential for use by food industries. The aim of this study was to characterise the bacteriocinogenic potential and activity of Lactobacillus isolates. From a lactic acid bacteria culture collection obtained from raw milk and cheese, 27 isolates were identified by 16S rDNA as Lactobacillus spp. and selected for the detection of lantibiotics biosynthesis genes, bacteriocin production, antimicrobial spectra, and ideal incubation conditions for bacteriocin production. Based on the obtained results, 21 isolates presented at least one of the three lantibiotics biosynthesis genes (lanB, lanC or lamM), and 23 isolates also produced antimicrobial substances with sensitivity to at least one proteinase, indicating their bacteriocinogenic activity. In general, the isolates had broad inhibitory activity, mainly against Listeria spp. and Staphylococcus spp. strains, and the best antimicrobial performance of the isolates occurred when they were cultivated at 25 °C for 24 or 48 h or at 35 °C for 12 h. The present study identified the bacteriocinogenic potential of Lactobacillus isolates obtained from raw milk and cheese, suggesting their potential use as biopreservatives in foods.     

Efficacy of a Broad Host Range Lytic Bacteriophage Against <Emphasis Type="Italic">E. coli</Emphasis> Adhered to Urothelium

Persistent urinary tract infections (UTI) are often caused by E. coli adhered to urothelium. This type of cells is generally recognized as very tolerant to antibiotics which renders difficult the treatment of chronic UTI. This study investigates the use of lytic bacteriophages as alternative antimicrobial agents, particularly the interaction of phages with E. coli adhered to urothelium and specifically determines their efficiency against this type of cells. The bacterial adhesion to urothelium was performed varying the bacterial cell concentrations and the period and conditions (static, shaken) of adhesion. Three collection bacteriophages (T1, T4, and phiX174 like phages) were tested against clinical E. coli isolates and only one was selected for further infection experiments. Based on the lytic spectrum against clinical isolates and its ability to infect the highest number of antibiotic resistant strains, the T1-like bacteriophage was selected. This bacteriophage caused nearly a 45% reduction of the bacterial population after 2 h of treatment. This study provides evidence that bacteriophages are effective in controlling suspended and adhered cells and therefore can be a viable alternative to antibiotics to control urothelium- adhered bacteria.     

Occurrence of the genes encoding carbapenemases,ESBLs and class 1 integron-integrase among fermenting and non-fermenting bacteria from retail goat meat

The present study was planned to detect the genes encoding carbapenemases, ESBLs and class 1 integron-integrase among bacteria obtained from retail goat meat. Fermenting and non-fermenting bacterial isolates (n = 57), recovered from 61 goat meat samples, were identified by 16S rRNA gene sequencing. Antimicrobial susceptibility of isolates was tested by the broth dilution method using ceftazidime, cefotaxime, meropenem and imipenem. Plasmids were isolated and tested for their physical characters. Plasmids were subjected to screening of carbapenemase, ESBL and intI1 gene. Conjugation assay was performed using bla_NDM-positive isolates as the donor, and Escherichia coli HB101 as the recipient. Isolates showed the high rates of resistance to ceftazidime (77·2%), cefotaxime (70·2%), meropenem (22·8%) and imipenem (17·5%). They showed variability in number and size (~1 to >20 kb) of plasmids. Among all, 1, 4, 13 and 31 isolates showed the bla_KPC, bla_NDM, bla_SHV and bla_TEM genes, respectively. The bla_KPC-2 gene was observed in one E. coli isolate. The bla_NDM-1 gene was detected in Stenotrophomonas maltophilia (n = 2), Acinetobacter baumannii (n = 1) and Ochrobactrum anthropi (n = 1) isolates. These isolates co-harboured the bla_TEM and bla_SHV genes. The intI1 gene was detected in 22 (38·6%) isolates, and 16 of these isolates showed the carbapenemase and/or ESBL genes. The conjugative movement of bla_NDM gene could not be proved after three repetitive mating experiments. The presence of genes encoding carbapenemases and ESBLs in bacteria from goat meat poses public health risks.     

Phylogenetic and phenotypic analyses of arsenic-reducing bacteria isolated from an old tin mine area in Thailand

An agar plate screening assay was used to determine whether 100 arsenic-resistant bacterial isolates, previously obtained from arsenic-contaminated soils, had the ability to transform arsenite and arsenate. Ninety-five percent of the isolates were capable of reducing arsenate on agar plates. The isolates also grew in the presence of high concentrations of arsenite, but none of the bacterial isolates oxidized arsenite to arsenate under the growth conditions tested. About 14 % (13 of 95) of the tested isolates transformed high levels of arsenate (33–70 μM) when tested using the molybdenum blue method. Partial sequence analysis of 16S rDNA genes indicated that the isolates belonged to two broad taxonomic groups: Firmicutes and Proteobacteria. Ten isolates were assigned to four species in the genus Bacillus, and three isolates belonged to two species in the genera Enterobacter and Ochrobactrum. Taken together these results indicate that phylogenetically diverse bacteria isolated from arsenic-contaminated soils in an old tin mine area in Thailand have the ability to transform arsenate to arsenite.     

Uterine Microbiology and Antimicrobial Susceptibility in Isolated Bacteria from Mares with Fertility Problems

Uterine microbiology and antimicrobial susceptibility was investigated in 239 mares with fertility problems in a prospective study in Sweden. Uterine swab samples were collected with double guarded swabs and transported overnight before being cultured. The Minimum Inhibitory Concentrations (MIC) was determined for a panel of antimicrobials. From 152 of the 239 mares at least one bacterial species was isolated, most frequently E. coli (104 isolates), β -haemolytic streptococci (31) and fungi (16). β -haemolytic streptococci were more frequently (p < 0.01) associated with clinical endometritis than with repeat breeding. The opposite was true for E. coli (p < 0.01). Among β -haemolytic streptococcal isolates some resistance was noted for 4 of 11 tested antibiotics, however, all isolates were susceptible to the widely used penicillin G. Among E. coli isolates enrofloxacin was the only of the 10 tested antibiotics for which no resistance was noted. Resistance was most commonly noted to cephalothin (39% of the isolates), streptomycin (22%), trimethoprim/sulphamethoxazole (15%) and ampicillin (11%). In conclusion, we show that both E. coli and β -haemolytic streptococci are frequently associated with fertility problems in mares and that antimicrobial resistance is a common feature of E. coli but also recognised for β -haemolytic streptococcal uterine isolates.