Urban ants and transportation of nosocomial bacteria

Many ant species displaying synanthropic behavior that have successfully dispersed in urban areas can cause problems in hospitals by acting as bacterial vectors. In this study, we encountered bacteria on ants collected at the Universidade Federal de Uberlandia hospital, in the campus and at households nearby. The ants were identified as Tapinoma melanocephalum (Fabricius) and Camponotus vittatus (Forel) (Hymenoptera: Formicidae) and the bacterial strains found here belong to the group of the coagulase-positive staphylococcus, coagulase-negative staphylococcus and gram negative bacilli, including antimicrobial drug-resistant strains. An investigation of the bacteria found in the ants and in the environment revealed that some ants carried non-isolated bacteria from the same environment and with high levels of resistance, evidencing the transmission potential of these insects.     

178例小儿肺炎分离菌分布和耐药性分析

目的 了解小儿肺炎病原菌谱及耐药性。方法 对2003～2004年178例小儿肺炎的痰标本进行细菌学培养,测定药物敏感性。结果 分离菌中,以革兰阴性菌居首位．占58．51％。肺炎克雷伯菌和大肠埃希菌为主琴芦种,对亚胺培南、美罗培南的耐药性最低;其次为革兰阳性菌,占40．43％,以金黄色葡萄球菌为主,耐甲氧西林的葡萄球菌为57．1％,对万古霉素、替考拉宁最敏感。结论 小儿肺炎病原菌以革兰阴性菌为主,并且出现多重耐药。临床上应避免盲目经验性用药,减少或减缓细菌耐药的发生。     

Isolation and phylogenetic analysis of bacteria with antimicrobial activities from the Mediterranean sponges Aplysina aerophoba and Aplysina cavernicola

The aim of this study was to isolate bacteria with antimicrobial activities from the marine sponges Aplysina aerophoba and Aplysina cavernicola. The obtained 27 isolates could be subdivided into eight phylogenetically different clusters based on comparative sequence analysis of their 16S rDNA genes. The sponge isolates were affiliated with the low (Bacillus) and high G+C Gram-positive bacteria (Arthobacter, Micrococcus), as well as the alpha-Proteobacteria (unknown isolate) and gamma-Proteobacteria (Vibrio, Pseudoalteromonas). One novel Bacillus species was identified and two species were closely related to previously uncharacterized strains. Isolates with antimicrobial activity were numerically most abundant in the genera Pseudoalteromonas and the alpha-Proteobacteria. The sponge isolates show antimicrobial activities against Gram-positive and Gram-negative reference strains but not against the fungus Candida albicans. A general pattern was observed in that Gram-positive bacteria inhibited Gram-positive strains while Gram-negative bacteria inhibited Gram-negative isolates. Antimicrobial activities were also found against clinical isolates, i.e. multi-resistant Staphylococcus aureus and Staphylococcus epidermidis strains isolated from hospital patients. The high recovery of strains with antimicrobial activity suggests that marine sponges represent an ecological niche which harbors a hitherto largely uncharacterized microbial diversity and, concomitantly, a yet untapped metabolic potential.     

Comparison of antimicrobial resistance patterns between clinical and sewage isolates in a regional hospital in Taiwan

Aims:  To compare bacterial populations and antimicrobial resistance patterns between clinical and sewage isolates from a regional hospital in northern Taiwan. The dissemination of antibiotic-resistant bacteria from hospital compartments to the hospital sewage treatment plant was examined.
Methods and Results:  A total of 1020 clinical isolates and 435 sewage isolates were collected between July and September 2005. The percentages of Gram-negative bacteria from the clinical and sewage isolates were 87·2% and 91·0%, respectively ( P  =   0·033). Escherichia coli were the leading bacterial isolates in both groups. Antimicrobial susceptibility testing showed a significant difference ( P  <   0·001) in resistance to ampicillin (85·6% vs 94·1%), ampicillin/sulbactam (31·7% vs 55·4%), cefazolin (29·2% vs 71·5%) and cefuroxime (20·7% vs 61·9%) between clinical and sewage coliform isolates, respectively.
Conclusions:  The sewage isolates had higher antimicrobial resistance rates than the clinical isolates from the same hospital.
Significance and Impact of the Study:  The low efficacy of the hospital sewage treatment may contribute to the dissemination of multidrug resistant bacteria from this hospital compartments to the environment. Practices which limit the disposal of antimicrobial agents into the wastewater system may be the possible measure to prevent the selection of multidrug-resistant bacteria from sewage treatment plants.     

Conjugative plasmids in multi-resistant bacterial isolates from Indian soil

Aims:  Determination of heavy metal and antibiotic resistance and presence of conjugative plasmids in bacteria isolated from soil irrigated with wastewater.
Methods and Results:  Composite soil samples were collected from Ghaziabad, Uttar Pradesh, India. Forty different bacteria were selected from nutrient agar and characterized by morphological, cultural and biochemical tests. All the isolates were tested for their resistance to different heavy metals and antibiotics. The DNA derived from multiple metal and antibiotic-resistant bacterial isolates was PCR amplified and plasmid-specific sequences (IncP, IncN, IncW, IncQ and pMV158-type) were analysed by dot blot hybridization. All isolates gave PCR products with trfA2 and oriT primers of the IncP group. These PCR products also hybridized with the RP4-derived probes. However, the samples were negative for all the other investigated plasmids as proved by PCR and dot blots.
Conclusions:  The presence of conjugative/mobilizable IncP plasmids in the isolates indicates that these bacteria have gene-mobilizing capacity with implications for potential dissemination of introduced recombinant DNA.
Significance and Impact of the Study:  The detection of IncP plasmids in all the bacterial isolates is another proof for the prevalence of these plasmids. We propose that IncP plasmids are mainly responsible for the spread of multi-resistant bacteria in these soils.     

The Spread of Multi Drug Resistant Infections Is Leading to an Increase in the Empirical Antibiotic Treatment Failure in Cirrhosis: A Prospective Survey

BackgroundThe spread of multi-resistant infections represents a continuously growing problem in cirrhosis, particularly in patients in contact with the healthcare environment.AimOur prospective study aimed to analyze epidemiology, prevalence and risk factors of multi-resistant infections, as well as the rate of failure of empirical antibiotic therapy in cirrhotic patients.MethodsAll consecutive cirrhotic patients hospitalized between 2008 and 2013 with a microbiologically-documented infection (MDI) were enrolled. Infections were classified as Community-Acquired (CA), Hospital-Acquired (HA) and Healthcare-Associated (HCA). Bacteria were classified as Multidrug-Resistant (MDR) if resistant to at least three antimicrobial classes, Extensively-Drug-Resistant (XDR) if only sensitive to one/two classes and Pandrug-Resistant (PDR) if resistant to all classes.ResultsOne-hundred-twenty-four infections (15% CA, 52% HA, 33% HCA) were observed in 111 patients. Urinary tract infections, pneumonia and spontaneous bacterial peritonitis were the more frequent. Forty-seven percent of infections were caused by Gram-negative bacteria. Fifty-one percent of the isolates were multi-resistant to antibiotic therapy (76% MDR, 21% XDR, 3% PDR): the use of antibiotic prophylaxis (OR = 8.4; 95%CI = 1.03-76; P = 0,05) and current/recent contact with the healthcare-system (OR = 3.7; 95%CI = 1.05-13; P = 0.04) were selected as independent predictors. The failure of the empirical antibiotic therapy was progressively more frequent according to the degree of resistance. The therapy was inappropriate in the majority of HA and HCA infections.ConclusionsMulti-resistant infections are increasing in hospitalized cirrhotic patients. A better knowledge of the epidemiological characteristics is important to improve the efficacy of empirical antibiotic therapy. The use of preventive measures aimed at reducing the spread of multi-resistant bacteria is also essential.     

外科血培养标本中病原菌分布及耐药性分析

目的了解中山大学附属第一医院外科血标本中病原菌的菌种分布及常见菌株的耐药性。方法血标本用Bact/A lert-120全自动血培养仪进行血培养,阳性血培养转种后用VITEK-60 AMS细菌鉴定仪鉴定,用K-B法进行药敏试验。结果2002年1月至2005年12月血培养标本中共分离出病原菌256株,阳性率为10.6%。122株(47.7%)为革兰阴性杆菌,其中肠杆菌科细菌占72.1%(88/122),非发酵菌占27.9%(34/122);113株(44.1%)为革兰阳性球菌,其中葡萄球菌属占51.3%(58/113),肠球菌占38.1%(43/113);真菌21株(8.2%)。血培养中的革兰阴性杆菌对亚胺培南、美洛培南治疗敏感;革兰阳性球菌对万古霉素和替考拉宁敏感。结论肠杆菌科细菌和葡萄球菌是外科血培养中的主要病原菌,其耐药现象严重,宜根据药敏结果选用敏感抗菌药物治疗。     

Phylogenetic analysis of mutualistic filamentous bacteria associated with fungus-growing ants

The attine ant-microbe system is a quadripartite symbiosis, involving a complex set of mutualistic and parasitic associations. The symbiosis includes the fungus-growing ants (tribe Attini), the basidiomycetous fungi the ants cultivate for food, specialized microfungal parasites (in the genus Escovopsis) of the cultivar, and ant-associated mu tualistic filamentous bacteria that secrete antibiotics specifically targeted to suppress the growth of Escovopsis. In this study, we conduct the first phylogenetic analysis of the filamentous mutualistic bacteria (actinomycetes) associated with fungus-growing ants. The filamentous bacteria present on 3 genera of fungus-growing ants (Acromyrmex, Trachy myrmex, and Apterostigma) were isolated from 126 colonies. The isolated actinomycetes were grouped into 3 distinct morphological types. Each morphological type was specific to the ant genus from which it was isolated, suggesting some degree of host specificity. The phylogenetic position of the 3 morphotypes was estimated using 16S rDNA for representative strains. The 8 isolates of actinomycetes sequenced are in the family Pseudonocardiaceae (Actino mycetales) and belong to the genus Pseudonocardia. Transmission electron microscopy examination of the actino mycete associated with the cuticle of Acromyrmex sp. revealed bacterial cells with an outer electron-dense membrane, consistent with actinomycetes in the genus Pseudonocardia. Ant-associated Pseudonocardia isolates did not form a monophyletic group, suggesting multiple acquisitions of actinomycetes by fungus-growing ants over their evolutionary history.     

677例新生儿咽拭子细菌培养及病原菌的耐药性分析

为观察首都医科大学附属北京妇产医院新生儿重症监护室(neonatal intensive care unit,NICU)患儿主要定植细菌及其抗生素耐药情况,以便采取相应措施及时控制医院内感染,本研究选择2014年8月1日-2015年5月31日住院患儿的咽试子标本进行细菌培养,同时进行耐药性分析。677例新生儿咽拭子培养结果显示,230例阳性(34.0%),其中革兰阳性球菌159例(69.1%),革兰阴性杆菌71例(30.9%)。定植细菌中,革兰阳性球菌主要为草绿色链球菌、克氏库克菌及表皮葡萄球菌,革兰阴性杆菌主要为大肠埃希菌、鲍曼不动杆菌及肺炎克雷伯菌。各细菌对常用抗生素的耐药率不同,同时进行药敏试验有助于指导临床用药。     

Resistance to aminoglycoside antibiotics of gram-negative bacilli isolated in Canadian hospitals.

A survey was made of the frequency of resistance to amikacin, gentamicin and tobramycin among aerobic gram-negative bacilli isolated over a 4-week period in 1979 at six large, geographically separated Canadian hospitals. In the entire series of 4407 isolates the frequency of resistance was 2.5% to amikacin, 8.1% to gentamicin, 5.9% to tobramycin and 1.7% to all three. Most (81%) of the resistant bacteria were acquired by the patients after admission to hospital. The frequency of resistance to the three aminoglycoside antibiotics in each hospital largely reflected the local rate of cross-infection by endemic strains of resistant bacteria.     

红火蚁及其他两种蚂蚁毒腺细菌鉴定与多样性分析(英文)

【目的】本研究旨在分析红火蚁Solenopsis invicta毒腺细菌群落多样性,并与热带火蚁Solenopsis geminata和聚纹双刺猛蚁Diacamma rugosum比较毒腺细菌群落差异。【方法】采用Illumine Hiseq 2500测序平台对红火蚁(工蚁、有翅蚁和蚁后)、热带火蚁(工蚁)及聚纹双刺猛蚁(工蚁)毒腺细菌群落16S rRNA基因V3-V4区测序,基于测序数据进行生物信息学分析。【结果】变形菌门(Proteobacteria)在红火蚁工蚁、有翅蚁和蚁后以及热带火蚁工蚁毒腺中占优势,而厚壁菌门(Firmicutes)在聚纹双刺猛蚁工蚁毒腺中占优势。与红火蚁工蚁和有翅蚁相比,柔壁菌门(Tenericutes)在红火蚁蚁后毒腺中更丰富。广州红火蚁蚁后毒腺中假单胞杆菌Pseudomonas相对丰度显著高于其在有翅蚁及工蚁中的。螺原体Spiroplasma相对丰度在热带火蚁毒腺中显著高于在聚纹双刺猛蚁工蚁毒腺中的。毒腺中细菌多样性分析发现,芽孢杆菌属Bacillus和乳酸杆菌属Lactobacillus在广西红火蚁工蚁中的相对丰度显著高于在广州红火蚁工蚁中的。然而,乳酸杆菌属细菌在聚纹双刺猛蚁工蚁毒腺中的相对丰度显著高于广西的热带火蚁工蚁毒腺中的。【结论】毒腺细菌组成和多样性在3种不同种类蚂蚁工蚁和红火蚁不同品级中存在差异。     

Highly similar microbial communities are shared among related and trophically similar ant species

Ants dominate many terrestrial ecosystems, yet we know little about their nutritional physiology and ecology. While traditionally viewed as predators and scavengers, recent isotopic studies revealed that many dominant ant species are functional herbivores. As with other insects with nitrogen-poor diets, it is hypothesized that these ants rely on symbiotic bacteria for nutritional supplementation. In this study, we used cloning and 16S sequencing to further characterize the bacterial flora of several herbivorous ants, while also examining the beta diversity of bacterial communities within and between ant species from different trophic levels. Through estimating phylogenetic overlap between these communities, we tested the hypothesis that ecologically or phylogenetically similar groups of ants harbor similar microbial flora. Our findings reveal: (i) clear differences in bacterial communities harbored by predatory and herbivorous ants; (ii) notable similarities among communities from distantly related herbivorous ants and (iii) similar communities shared by different predatory army ant species. Focusing on one herbivorous ant tribe, the Cephalotini, we detected five major bacterial taxa that likely represent the core microbiota. Metabolic functions of bacterial relatives suggest that these microbes may play roles in fixing, recycling, or upgrading nitrogen. Overall, our findings reveal that similar microbial communities are harbored by ants from similar trophic niches and, to a greater extent, by related ants from the same colonies, species, genera, and tribes. These trends hint at coevolved histories between ants and microbes, suggesting new possibilities for roles of bacteria in the evolution of both herbivores and carnivores from the ant family Formicidae.     

Culture-independent identification of gut bacteria in fourth-instar red imported fire ant, Solenopsis invicta Buren, larvae

Red imported fire ants (RIFA), Solenopsis invicta Buren, are medical, urban, and agricultural pests from South America. They are successful invaders due to their preference for disturbed habitats, high reproductive rates, and the ability to feed on a wide variety of food items (omnivorous). Fourth-instar larvae are used by the colony to digest solid food and then regurgitate it for consumption by workers and queens. Larvae are an ideal source of investigations of endosymbiotic bacteria possibly involved in nutrient distributions. Our study utilized 16S rDNA sequencing to describe the composition of the bacterial community in fourth-instar ant larvae in order to identify possible endosymbiotic bacteria present therein. The 16S rRNA gene was directly amplified from mixed-population DNA of whole fire ant larval guts and cloned into Escherichia coli. Bacterial communities from three geographically separated RIFA colonies were examined. Sequenced bacterial clones from guts were determined to be predominantly from the phylum Proteobacteria and the family Enterobacteriaceae. Our results did not detect the presence of endosymbiotic bacteria in the guts of RIFA larvae among the colonies. In addition, minimal species overlap was found when bacterial inventories were compared among colonies. Thus, bacteria coadapted with red imported fire ant larvae were not detected. Identified bacteria were not closely affiliated with endosymbiotic bacteria common in other insect species. Bacteria communities appeared to be unique to each geographical location and were determined by the foods consumed by the ants.     

Cytological and Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization Studies on Lactobacillus Isolates from San Francisco Sourdough

Molecular taxonomic and electron microscopy studies were performed on four bacterial isolates obtained from different sources of San Francisco sourdough (SD). These bacteria were first isolated by Kline and Sugihara who tentatively described them as a previously unreported species of heterofermentative Lactobacillus; they suggested the name Lactobacillus sanfrancisco. The guanine plus cytosine base composition (%GC) of the deoxyribonucleic acid (DNA) ranged from 38 to 40%. The possible genetic relatedness of these SD isolates to five known species of Lactobacillus with comparable GC contents was assessed in the present work by means of DNA-DNA hybridization competition experiments. Little or no DNA homology was observed between the SD bacteria and the known species. The SD bacteria exhibited a high degree of homology (>88%) among themselves, suggesting that the four isolates were identical taxonomically. Also, the electron photomicrographs revealed structures similar to those of gram-positive bacilli. Accordingly, since these SD isolates have the characteristic phenotypic and morphological properties of the genus Lactobacillus and are not related genetically to any known species, the tentative characterization by the above workers of these isolates as a new species is substantiated.     

Opportunist slave-making ants Myrmoxenus ravouxi discriminate different host species from a non-host species

Slave-making ants exploit the worker force of host colonies permanently and have to make recurrent raids in order to replenish the slave’s stock. Some of these parasite species exploit different host species and few studies so far have been devoted to host species recognition mechanisms. Here, we tried to determine if opportunist slave-making ants using different host species rely on innate or experience-induced preferences to discriminate host from non-host species. We show that Myrmoxenus ravouxi slave-making workers are not only more aggressive toward heterocolonial host and potential host species workers when compared with non-host species workers, but also toward heterocolonial host workers than toward heterocolonial conspecifics. Moreover, M. ravouxi workers display more antennations and contacts toward the heterocolonial host species when compared with the non-host species. We also show that they do not discriminate between homocolonial and heterocolonial conspecifics. Together, our results suggest that this opportunistic slave-making ant species may have a complex social recognition template based on both innate and experience-based mechanisms.     

Novel methicillin-resistant coagulase-negative Staphylococcus clone isolated from patients with haematological diseases at the Blood Bank Centre of Amazon,Brazil

Methicillin-resistant Staphylococcus remains a severe public health problem worldwide. This research was intended to identify the presence of methicillin-resistant coagulase-negative staphylococci clones and their staphylococcal cassette chromosome mec (SCCmec)-type isolate from patients with haematologic diseases presenting bacterial infections who were treated at the Blood Bank of the state of Amazonas in Brazil. Phenotypic and genotypic tests, such as SCCmec types and multilocus sequence typing (MLST), were developed to detect and characterise methicillin-resistant isolates. A total of 26 Gram-positive bacteria were isolated, such as: Staphylococcus epidermidis (8/27), Staphylococcus intermedius (4/27) and Staphylococcus aureus (4/27). Ten methicillin-resistant staphylococcal isolates were identified. MLST revealed three different sequence types: S. aureus ST243, S. epidermidis ST2 and a new clone of S. epidermidis, ST365. These findings reinforce the potential of dissemination presented by multi-resistant Staphylococcus and they suggest the introduction of monitoring actions to reduce the spread of pathogenic clonal lineages of S. aureus and S. epidermidis to avoid hospital infections and mortality risks.     

Microbial symbionts are shared between ants and their associated beetles

The transmission of microbial symbionts across animal species could strongly affect their biology and evolution, but our understanding of transmission patterns and dynamics is limited. Army ants (Formicidae: Dorylinae) and their hundreds of closely associated insect guest species (myrmecophiles) can provide unique insights into interspecific microbial symbiont sharing. Here, we compared the microbiota of workers and larvae of the army ant Eciton burchellii with those of 13 myrmecophile beetle species using 16S rRNA amplicon sequencing. We found that the previously characterized specialized bacterial symbionts of army ant workers were largely absent from ant larvae and myrmecophiles, whose microbial communities were usually dominated by Rickettsia, Wolbachia, Rickettsiella and/or Weissella. Strikingly, different species of myrmecophiles and ant larvae often shared identical 16S rRNA genotypes of these common bacteria. Protein-coding gene sequences confirmed the close relationship of Weissella strains colonizing army ant larvae, some workers and several myrmecophile species. Unexpectedly, these strains were also similar to strains infecting dissimilar animals inhabiting very different habitats: trout and whales. Together, our data show that closely interacting species can share much of their microbiota, and some versatile microbial species can inhabit and possibly transmit across a diverse range of hosts and environments.     

Commensal bacilli inhibitory to mastitis pathogens isolated from the udder microbiota of healthy cows

AIMS: To isolate from the microbiota of the healthy cow udder commensal bacteria having antimicrobial activity against bovine mastitis pathogens, with a long-term view to their potential application as antimastitis probiotics. METHODS AND RESULTS: Bacterial isolates from four healthy cow udders were tested for inhibitory activity against three Gram-positive indicator bacteria. This led to the selection of nine broadly inhibitory strains. All were of the Bacillus genus and their antimicrobial activities, which appeared heterogeneous on the basis of their antibacterial spectra and heat susceptibilities, enabled grouping of the inhibitory bacilli into six different inhibitory profiles. All displayed strong in vitro activity against Gram-positive mastitis pathogens. Inhibitory bacilli were recovered from each of the 11 udder samples collected over 7 months from one of these cows and the isolates included representatives of all six inhibitory profiles. CONCLUSIONS: Bacilli present in the udder microbiota of healthy cows can produce a variety of broadly active inhibitors of Gram-positive bacteria, including potential mastitis pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: Inhibitor-producing strains of commensal Bacillus species have been identified, which may have the potential for use as possible antimastitis probiotics.     

The Effect of Diet and Opponent Size on Aggressive Interactions Involving Caribbean Crazy Ants (Nylanderia fulva)

Biotic interactions are often important in the establishment and spread of invasive species. In particular, competition between introduced and native species can strongly influence the distribution and spread of exotic species and in some cases competition among introduced species can be important. The Caribbean crazy ant, Nylanderia fulva, was recently introduced to the Gulf Coast of Texas, and appears to be spreading inland. It has been hypothesized that competition with the red imported fire ant, Solenopsis invicta, may be an important factor in the spread of crazy ants. We investigated the potential of interspecific competition among these two introduced ants by measuring interspecific aggression between Caribbean crazy ant workers and workers of Solenopsis invicta. Specifically, we examined the effect of body size and diet on individual-level aggressive interactions among crazy ant workers and fire ants. We found that differences in diet did not alter interactions between crazy ant workers from different nests, but carbohydrate level did play an important role in antagonistic interactions with fire ants: crazy ants on low sugar diets were more aggressive and less likely to be killed in aggressive encounters with fire ants. We found that large fire ants engaged in fewer fights with crazy ants than small fire ants, but fire ant size affected neither fire ant nor crazy ant mortality. Overall, crazy ants experienced higher mortality than fire ants after aggressive encounters. Our findings suggest that fire ant workers might outcompete crazy ant workers on an individual level, providing some biotic resistance to crazy ant range expansion. However, this resistance may be overcome by crazy ants that have a restricted sugar intake, which may occur when crazy ants are excluded from resources by fire ants.     

Capacity for polyphosphate accumulation of predominant bacteria in activated sludge showing enhanced phosphate removal

The taxonomic identity of predominant bacteria in laboratory-scale anaerobic-aerobic activated sludge systems and their capacity for accumulating polyphosphate (polyP) were investigated. All bacterial isolates accumulated appreciable amounts of polyP under tested conditions, although only 7% of them were positive for the volutin stain. The isolates showing the most pronounced polyP accumulation and volutin formation were the unidentified Gram-positive bacteria containing menaquinone—10. Some other strains of Gram-positive bacteria and menaquinone-containing Gram-negative bacteria also formed volutin granules.