Two Pseudomonas aeruginosa clonal groups belonging to the PA14 clade are indigenous to the Churince system in Cuatro Ciénegas Coahuila,México

Pseudomonas aeruginosa is a widely distributed environmental bacterium but is also an opportunistic pathogen that represents an important health hazard due to its high intrinsic antibiotic resistance and its production of virulence factors. The genetic structure of P. aeruginosa populations using whole genome sequences shows the existence of three clades, one of which (PA7 clade) has a higher genetic diversity. These three clades include clinical and environmental isolates that are very diverse in terms of geographical origins and isolation date. Here, we report the characterization of two distinct clonal P. aeruginosa groups that form a part of the PA14 clade (clade 2) sampled from the Churince system in Cuatro Ciénegas Basin (CCB). One of the clonal groups that we report here was isolated in 2011 (group 2A) and was displaced by the other clonal group (2B) in 2015. Both Churince groups are unable to produce pyoverdine but can produce other virulence-associated traits. The existence of these unique P. aeruginosa clonal groups in the Churince system is of ecological and evolutionary significance since the microbiota of this site is generally very distinct from other lineages, and this is the first time that a population of P. aeruginosa has been found in CCB.     

Genetic analyses of Pseudomonas aeruginosa isolated from healthy captive snakes: evidence of high inter‐ and intrasite dissemination and occurrence of antibiotic resistance genes

Faecal carriage of Pseudomonas aeruginosa was investigated by selective plating and PCR identification test, among healthy captive snakes from zoological and private collections from France as well as from wild snakes from Guinea. P. aeruginosa faecal carriage among captive snakes was high (72 out of 83 individuals), but low among wild specimen (3 out of 23 individuals). Genetic diversity analyses of the isolates, based on SpeI‐PFGE profiles, evidenced five dominant clones or clonal complexes spreading among snakes within a site and between sites and persisting over time. Similar clones or clonal complexes were detected from mouth swabs of the owners and from water and preys used to feed the snakes, evidencing various sources of snake colonization and the first cases of P. aeruginosa cross‐contamination between snakes and owners. These observations led to the conclusion that P. aeruginosa behaves as an opportunistic species within snakes in captivity and that colonization and dissemination occurs consecutively to processes similar to those identified within the hospital. Antibiotic susceptibility testing showed that most isolates had a wild‐type resistance profile except for one persistent clone isolated from both snakes and preys that harboured multiple antimicrobial resistance genes mediated by an integron carrying the qacH, aadB, aadA2 and cmlA10 cassettes, and a tetA(C)‐carrying transposon. Biocides or antibiotics used in the zoological garden could have led to the acquisition of this integron.     

Biofilm formation in an experimental water distribution system: the contamination of non-touch sensor taps and the implication for healthcare

Hospital tap water is a recognised source of Pseudomonas aeruginosa. UK guidance documents recommend measures to control/minimise the risk of P. aeruginosa in augmented care units but these are based on limited scientific evidence. An experimental water distribution system was designed to investigate colonisation of hospital tap components. P. aeruginosa was injected into 27 individual tap ‘assemblies’. Taps were subsequently flushed twice daily and contamination levels monitored over two years. Tap assemblies were systematically dismantled and assessed microbiologically and the effect of removing potentially contaminated components was determined. P. aeruginosa was repeatedly recovered from the tap water at levels above the augmented care alert level. The organism was recovered from all dismantled solenoid valves with colonisation of the ethylene propylene diene monomer (EPDM) diaphragm confirmed by microscopy. Removing the solenoid valves reduced P. aeruginosa counts in the water to below detectable levels. This effect was immediate and sustained, implicating the solenoid diaphragm as the primary contamination source.     

Molecular epidemiology of pseudomonas aeruginosa clinical isolates from Portuguese Central Hospital

The relatedness between clinical isolates of P. aeruginosa obtained from patients during their stay in a Portuguese Central Hospital was evaluated. Genotypic fingerprinting (M13-PCR), phenotypic methods (biotyping and antibiotyping) and epidemiological information (spatial and temporal links) were used to evaluate the relatedness between 88 clinical isolates (68 patients), selected randomly out of 189. Sixty-two M13 types were found, 12 of them containing isolates from more than one patient. Thirty-four antibiotypes were found, as well as a significant association (p < 0.05) between epidemic isolates and multiresistance patterns. The nosocomial transmission of P. aeruginosa strains may be limited since M13 typing demonstrated a high degree of diversity among all the isolates, suggesting the occurrence of mainly independent infectious episodes. The results show the possible occurrence of cross-acquisition, cross-colonization and cross-infection and suggest an epidemic population structure for P. aeruginosa in this hospital.     

Identification of Two Multidrug-Resistant <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Clonal Lineages with a Countrywide Distribution in Hungary

The aim of this study was to identify class 1 integrons from extended-spectrum and metallo-β-lactamase-negative, multidrug-resistant Pseudomonas aeruginosa clinical isolates from Hungary and to characterize the isolates by phenotypic and molecular methods. Fourteen selected P. aeruginosa isolates resistant to ceftazidime, gentamicin, and ciprofloxacin were subjected to serotyping, random amplification of polymorphic DNA (RAPD), integron content analysis, and a phenotypic test to detect high-level production of AmpC. Four representative isolates were further analyzed by multilocus sequence typing. Two P. aeruginosa multidrug-resistant clonal lineages were identified with a countrywide distribution. The first lineage is characterized by serotype O4, RAPD genotype A, sequence type ST175, and the presence of a class 1 integron harbouring aadB and aadA13 gene cassettes in its variable region. The second lineage is characterized by serotype O6, RAPD genotype B, sequence type ST395, and a class 1 integron carrying a single aadB cassette. The corresponding isolates were recovered from altogether 11 towns in Hungary. ST175 and ST395 are the presently calculated founders of two distinct P. aeruginosa clonal complexes that appear to have a wide geographical distribution also outside Hungary. The multidrug-resistant phenotype associated with these two clonal lineages might have contributed to an increase in their frequency and to their subsequent diversification. Both P. aeruginosa lineages displayed ≥8-fold synergy with boronic acid/ceftazidime combinations, suggesting an AmpC-mediated resistance to ceftazidime. Our observations underscore the role of class 1 integrons in the spread of aminoglycoside resistance by clonal dissemination among P. aeruginosa clinical isolates in Hungary.     

Hartmanella vermiformis can be permissive for Pseudomonas aeruginosa

Aims: The amoebae of the genus Hartmanella are frequently recovered from hospital water taps, whereas Pseudomonas aeruginosa is often implicated in nosocomial infections. Previous works suggested that free living amoebae can act as vehicles of bacterial transmission. The present work investigates the relationships between a strain of Hartmanella vermiformis and three strains of P. aeruginosa: a reference strain, a strain from a patient and an environmental strain. Methods and Results: In a saline medium, H. vermiformis is not able to favour for the development of P. aeruginosa. In a rich co‐cultivation medium, only the environmental strain has shown a growth. Conclusions: We showed that P. aeruginosa is not a good nutrient source for H. vermiformis. Significance and Impact of the Study: Nevertheless, in particular conditions and with particular strains, the presence of H. vermiformis could represent a possibility of growth for P. aeruginosa.     

Microsatellite evidence for high clonality and limited genetic diversity in Ziziphus celata (Rhamnaceae), an endangered, self-incompatible shrub endemic to the Lake Wales Ridge, Florida, USA

Genetic data are often crucial for designing management strategies for rare and endangered species. Ziziphus celata is an endangered sandhill shrub endemic to the Lake Wales Ridge of central Florida. This self-incompatible clonal species is known from only 14 wild populations, most of which are small (under 100 plants). Focusing on the five populations discovered in 2007, we evaluate the level of genetic diversity and identify clonal lineages within the wild populations of the species with a set of microsatellite loci. To account for somatic mutations and genotyping errors, we identified clonal lineages using a threshold cutoff for pair-wise genetic distances among samples. The microsatellites had up to 18 alleles/locus, and, consistent with outcrossing, samples were highly heterozygous (average population level H _o  = 0.69). Most populations of Z. celata consist of a single clone, and the most diverse population has only 10 clones. Overall Z. celata comprises 41 multi-locus genotypes, and 30 clonal lineages. With nearly 1,000 recorded plants (595 genotyped) and only 30 clonal lineages, Ziziphus celata is highly clonal: clonal richness, R = 0.049. The pair-wise distance method facilitates identification of clonal lineages, avoiding overestimation of clonal diversity. In most cases, the samples that grouped into a lineage were one to four plants differing from a surrounding genotype by a single microsatellite repeat insertion/deletion mutation, consistent with these having arisen via somatic mutations. Our data will enable managers to incorporate extant diversity from wild populations into ex situ collections. Additionally, our research demonstrates the utility of microsatellites for conservation of imperiled species, identifying genotypes of high priority for preservation.     

Phenotypic Heterogeneity of Pseudomonas aeruginosa Populations in a Cystic Fibrosis Patient

The opportunistic pathogen Pseudomonas aeruginosa chronically infects the lower airways of patients with cystic fibrosis. Throughout the course of infection this organism undergoes adaptations that contribute to its long-term persistence in the airways. While P. aeruginosa diversity has been documented, it is less clear to what extent within-patient diversity contributes to the overall population structure as most studies have been limited to the analysis of only a few isolates per patient per time point. To examine P. aeruginosa population structure in more detail we collected multiple isolates from individual sputum samples of a patient chronically colonized with P. aeruginosa. This strain collection, comprised of 169 clonal isolates and representing three pulmonary exacerbations as well as clinically stable periods, was assayed for a wide selection of phenotypes. These phenotypes included colony morphology, motility, quorum sensing, protease activity, auxotrophy, siderophore levels, antibiotic resistance, and growth profiles. Each phenotype displayed significant variation even within isolates of the same colony morphotype from the same sample. Isolates demonstrated a large degree of individuality across phenotypes, despite being part of a single clonal lineage, suggesting that the P. aeruginosa population in the cystic fibrosis airways is being significantly under-sampled.     

Clonal diversity driven by parasitism in a freshwater snail

One explanation for the widespread abundance of sexual reproduction is the advantage that genetically diverse sexual lineages have under strong pressure from virulent coevolving parasites. Such parasites are believed to track common asexual host genotypes, resulting in negative frequency‐dependent selection that counterbalances the population growth‐rate advantage of asexuals in comparison with sexuals. In the face of genetically diverse asexual lineages, this advantage of sexual reproduction might be eroded, and instead sexual populations would be replaced by diverse assemblages of clonal lineages. We investigated whether parasite‐mediated selection promotes clonal diversity in 22 natural populations of the freshwater snail Melanoides tuberculata. We found that infection prevalence explains the observed variation in the clonal diversity of M. tuberculata populations, whereas no such relationship was found between infection prevalence and male frequency. Clonal diversity and male frequency were independent of snail population density. Incorporating ecological factors such as presence/absence of fish, habitat geography and habitat type did not improve the predictive power of regression models. Approximately 11% of the clonal snail genotypes were shared among 2–4 populations, creating a web of 17 interconnected populations. Taken together, our study suggests that parasite‐mediated selection coupled with host dispersal ecology promotes clonal diversity. This, in return, may erode the advantage of sexual reproduction in M. tuberculata populations.     

Clonal diversity in high arctic ostracodes

It remains unclear why the majority of parthenogenetic lineages persist for only brief periods of evolutionary time. However, by characterizing their patterns of genetic variation, it is possible to gain insights regarding their evolutionary origin and potential. We examined clonal diversity patterns in high arctic populations of freshwater ostracodes with the goal of clarifying the factors promoting genotypic diversity. Allozyme electrophoresis showed that the three dominant ostracode species in high arctic ponds reproduce via apomictic parthenogenesis that two of these species (Prionocypris glacialis, Candona rectangulata) were both highly clonally diverse, and had allozyme phenotypes suggestive of polyploidy. Scanning microdensitometry confirmed that many clones of P. glacialis at Igloolik were polyploid. In contrast to most other polyploids, clones of P. glacialis seem to be autopolyploids. Although clonal variation in P. glacialis may reflect multiple transitions to parthenogenesis in an undetected sexual population, it seems likely that genomic recombination associated with polyploidy has also played a role in generating local diversity following the transition to parthenogenesis.     

基于CiteSpace分析铜绿假单胞菌耐药性研究热点与趋势

【背景】铜绿假单胞菌(Pseudomonas aeruginosa)是临床引发感染的主要病原菌之一,对多种抗菌药物均有耐药性,临床治疗难度大,对该病原菌耐药性的研究一直备受关注。【目的】基于CiteSpace可视化功能,探究铜绿假单胞菌耐药性研究现状、热点与发展趋势。【方法】利用文献计量分析法,以2014–2021年中国知网(CNKI)、万方数据库(Wanfang)、Web of Science (WoS)共8 996篇铜绿假单胞菌耐药性的中英文文献为分析样本,运用Citespace软件对文献发文量、作者合作网络、国家和机构合作网络、文献共被引及期刊分析、关键词聚类、突现等方面进行分析,以探究该研究主题的研究热点及趋势。【结果】英文文献发文量增长速度高于中文文献;我国文献发文量仅次于美国、印度,在该领域科研成果贡献度较高,国际学术影响力较大;中英文文献中均对院内感染疾病和耐碳青霉烯类铜绿假单胞菌持高关注度。然而,中文文献较关注铜绿假单胞菌耐药性的临床防治问题,英文文献则较关注铜绿假单胞菌耐药性的基础研究。【结论】国内外铜绿假单胞菌耐药性研究对院内感染疾病及新型耐药菌的产生与防治关注度最高,暗示以上研究主题是该领域的研究热点与趋势。     

A layover in Europe: Reconstructing the invasion route of asexual lineages of a New Zealand snail to North America

Non‐native invasive species are threatening ecosystems and biodiversity worldwide. High genetic variation is thought to be a critical factor for invasion success. Accordingly, the global invasion of a few clonal lineages of the gastropod Potamopyrgus antipodarum is thus both puzzling and has the potential to help illuminate why some invasions succeed while others fail. Here, we used SNP markers and a geographically broad sampling scheme (N = 1617) including native New Zealand populations and invasive North American and European populations to provide the first widescale population genetic assessment of the relationships between and among native and invasive P. antipodarum. We used a combination of traditional and Bayesian molecular analyses to demonstrate that New Zealand populations harbour very high diversity relative to the invasive populations and are the source of the two main European genetic lineages. One of these two European lineages was in turn the source of at least one of the two main North American genetic clusters of invasive P. antipodarum, located in Lake Ontario. The other widespread North American group had a more complex origin that included the other European lineage and two New Zealand clusters. Altogether, our analyses suggest that just a small handful of clonal lineages of P. antipodarum were responsible for invasion across continents. Our findings provide critical information for prevention of additional invasions and control of existing invasive populations and are of broader relevance towards understanding the establishment and evolution of asexual populations and the forces driving biological invasion.     

Pseudomonas aeruginosa, Candida albicans, and device-related nosocomial infections: implications, trends, and potential approaches for control

For many years, device-associated infections and particularly device-associated nosocomial infections have been of considerable concern. Recently, this concern was heightened as a result of increased antibiotic resistance among the common causal agents of nosocomial infections, the appearance of new strains which are intrinsically resistant to the antibiotics of choice, and the emerging understanding of the role biofilms may play in device-associated infections and the development of increased antibiotic resistance. Pseudomonas aeruginosa and Candida albicans are consistently identified as some of the more important agents of nosocomial infections. In light of the recent information regarding device-associated nosocomial infections, understanding the nature of P. aeruginosa and C. albicans infections is increasingly important. These two microorganisms demonstrate: (1) an ability to form biofilms on the majority of devices employed currently, (2) increased resistance/tolerance to antibiotics when associated with biofilms, (3) documented infections noted for virtually all indwelling devices, (4) opportunistic pathogenicity, and (5) persistence in the hospital environment. To these five demonstrated characteristics, two additional areas of interest are emerging: (a) the as yet unclear relationship of these two microorganisms to those species of highly resistant Pseudomonas spp and Candida spp that are of increasing concern with device-related infections, and (b) the recent research showing the dynamic interaction of P. aeruginosa and C. albicans in patients with cystic fibrosis. An understanding of these two opportunistic pathogens in the context of their ecosystems/biofilms also has significant potential for the development of novel and effective approaches for the control and treatment of device-associated infections.     

Coexistence and Within-Host Evolution of Diversified Lineages of Hypermutable Pseudomonas aeruginosa in Long-term Cystic Fibrosis Infections

The advent of high-throughput sequencing techniques has made it possible to follow the genomic evolution of pathogenic bacteria by comparing longitudinally collected bacteria sampled from human hosts. Such studies in the context of chronic airway infections by Pseudomonas aeruginosa in cystic fibrosis (CF) patients have indicated high bacterial population diversity. Such diversity may be driven by hypermutability resulting from DNA mismatch repair system (MRS) deficiency, a common trait evolved by P. aeruginosa strains in CF infections. No studies to date have utilized whole-genome sequencing to investigate within-host population diversity or long-term evolution of mutators in CF airways. We sequenced the genomes of 13 and 14 isolates of P. aeruginosa mutator populations from an Argentinian and a Danish CF patient, respectively. Our collection of isolates spanned 6 and 20 years of patient infection history, respectively. We sequenced 11 isolates from a single sample from each patient to allow in-depth analysis of population diversity. Each patient was infected by clonal populations of bacteria that were dominated by mutators. The in vivo mutation rate of the populations was ∼100 SNPs/year–∼40-fold higher than rates in normo-mutable populations. Comparison of the genomes of 11 isolates from the same sample showed extensive within-patient genomic diversification; the populations were composed of different sub-lineages that had coexisted for many years since the initial colonization of the patient. Analysis of the mutations identified genes that underwent convergent evolution across lineages and sub-lineages, suggesting that the genes were targeted by mutation to optimize pathogenic fitness. Parallel evolution was observed in reduction of overall catabolic capacity of the populations. These findings are useful for understanding the evolution of pathogen populations and identifying new targets for control of chronic infections.     

Study on morphology,pathogenicity and genetic diversity of Wilsonomyces carpophilus isolates,the causal agent of shot hole of stone fruit trees based on RAPD-PCR in Iran

Shot hole disease is one of the most important diseases of stone fruit trees in Iran. The disease is wide spread among orchards of Prunus spp. During spring and summer of 2007, 80 monoconidial isolates of the pathogen were recovered from infected leaves, fruits and twigs of different Prunus spp. in West Azerbaijan, Tehran, Ghazvin and Razavi Khorasan provinces of Iran and were studied taxonomically. Based on morphological and physiological characteristics and growth optimal temperature, all isolates were identified as Wilsonomyces carpophilus. Seedlings of stone fruits (apricot, almond, peach, nectarine, plum, sweet cherry and sour cherry) were used for pathogenicity tests. All seedlings were susceptible to the fungal isolates and showed disease symptoms on twigs, leaves, buds and petioles. Genetic diversity of 28 selected fungal isolates was investigated based on DNA fingerprinting by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR), using four random primers. Based on cluster analysis of the PCR results from the four primers, 10 fingerprinting groups (clonal lineages) and 27 haplotypes were identified. Clonal lineages “C”, “D” and “E”, each with six haplotypes formed the biggest clonal lineages, but other clonal lineages (“B”, “F”, “G”, “H”, “I” and “J”) included only one isolate. No correlation was detected among clonal lineages with the location of selected isolates and their host species. A correlation was found between the substrate (fruit, twig or leaf) and clonal lineages, particularly in “C” clonal lineage. The results showed that the fungus population had high genetic diversity which is distributed among the different areas of Iran.     

Faster clonal turnover in high‐infection habitats provides evidence for parasite‐mediated selection

According to the Red Queen hypothesis for sex, parasite‐mediated selection against common clones counterbalances the reproductive advantage of asexual lineages, which would otherwise outcompete sexual conspecifics. Such selection on the clonal population is expected to lead to a faster clonal turnover in habitats where selection by parasites is stronger. We tested this prediction by comparing the genetic structure of clonal and sexual populations of freshwater snail Potamopyrgus antipodarum between years 2003 and 2007 in three depth‐specific habitats in Lake Alexandrina (South Island, New Zealand). These habitats differ in the risk of infection by castrating trematodes and in the relative proportion of sexual individuals. As predicted, we found that the clonal structure changed significantly in shallow and mid‐water habitats, where prevalence of infection was high, but not in the deep habitat, where parasite prevalence was low. Additionally, we found that both clonal diversity and evenness of the asexual population declined in the shallow habitat. In contrast, the genetic structure (based on F–statistics) of the coexisting sexual population did not change, which suggests that the change in the clonal structure cannot be related to genetic changes in the sexual population. Finally, the frequency of sexuals had no effect on the diversity of the sympatric clonal population. Taken together, our results show a more rapid clonal turnover in high‐infection habitats, which gives support for the Red Queen hypothesis for sex.     

Loss of Heterozygosity Drives Clonal Diversity of Phytophthora capsici in China

Phytophthora capsici causes significant loss to pepper (Capsicum annum) in China and our goal was to develop single nucleotide polymorphism (SNP) markers for P. capsici and characterize genetic diversity nationwide. Eighteen isolates of P. capsici from locations worldwide were re-sequenced and candidate nuclear and mitochondrial SNPs identified. From 2006 to 2012, 276 isolates of P. capsici were recovered from 136 locations in 27 provinces and genotyped using 45 nuclear and 2 mitochondrial SNPs. There were two main mitochondrial haplotypes and 95 multi-locus genotypes (MLGs) identified. Genetic diversity was geographically structured with a high level of genotypic diversity in the north and on Hainan Island in the south, suggesting outcrossing contributes to diversity in these areas. The remaining areas of China are dominated by four clonal lineages that share mitochondrial haplotypes, are almost exclusively the A1 or A2 mating type and appear to exhibit extensive diversity based on loss of heterozygosity (LOH). Analysis of SNPs directly from infected peppers confirmed LOH in field populations. One clonal lineage is dominant throughout much of the country. The overall implications for long-lived genetically diverse clonal lineages amidst a widely dispersed sexual population are discussed.     

Clonal diversity,clonal persistence and rapid taxon replacement in natural populations of species and hybrids of the Daphnia longispina complex

Hybridization is common among cyclical parthenogens, especially in zooplankton species assemblages of the genus Daphnia. To explore hybridization dynamics and the extent of clonal diversity in the Daphnia longispina complex, we analysed population structure in eight permanent lakes. Based on 15 microsatellite loci, three major taxonomic units emerged: two species, D. galeata and D. longispina and their F1 hybrids, supported by factorial correspondence analysis and two Bayesian methods. At the same time, the detection of backcross classes differed between methods. Mean clonal diversity was lowest in the F1 hybrids, as expected from the high rate of asexual reproduction. Within taxa, replicated genotypes were of clonal origin, but clonal lineages persisted in subsequent years in only one of three resampled lakes. In another lake, the taxon composition changed from being dominated by hybrids to complete dominance by one parental taxon. Such a year‐to‐year taxon replacement has not been reported for the D. longispina complex before. Our data on this hybrid complex illustrate that high‐resolution genotyping is essential for the understanding of ecological and evolutionary outcomes of hybridization in partially clonal taxa.     

High levels of diversity and population structure in the potato late blight pathogen at the Mexico centre of origin

Globally destructive crop pathogens often emerge by migrating out of their native ranges. These pathogens are often diverse at their centre of origin and may exhibit adaptive variation in the invaded range via multiple introductions from different source populations. However, source populations are generally unidentified or poorly studied compared to invasive populations. Phytophthora infestans, the causal agent of late blight, is one of the most costly pathogens of potato and tomato worldwide. Mexico is the centre of origin and diversity of P. infestans and migration events out of Mexico have enormously impacted disease dynamics in North America and Europe. The debate over the origin of the pathogen, and population studies of P. infestans in Mexico, has focused on the Toluca Valley, whereas neighbouring regions have been little studied. We examined the population structure of P. infestans across central Mexico, including samples from Michoacán, Tlaxcala and Toluca. We found high levels of diversity consistent with sexual reproduction in Michoacán and Tlaxcala and population subdivision that was strongly associated with geographic region. We determined that population structure in central Mexico has contributed to diversity in introduced populations based on relatedness of U.S. clonal lineages to Mexican isolates from different regions. Our results suggest that P. infestans exists as a metapopulation in central Mexico, and this population structure could be contributing to the repeated re‐emergence of P. infestans in the United States and elsewhere.     

铜绿假单胞菌群体感应信号分子PQS的功能多样性研究进展

铜绿假单胞菌(Pseudomonas aeruginosa)是一种革兰氏阴性条件致病菌,可对免疫功能低下或损伤的患者造成持续性感染。铜绿假单胞菌能成功感染离不开其自身产生的毒力因子,而这些毒力因子大多数都受群体感应系统(quorum sensing,QS)调控。铜绿假单胞菌有4个QS系统,分别为las系统、rhl系统、pqs系统和iqs系统。2-庚基-3-羟基-4-喹诺酮(Pseudomonas quinolone signal,PQS)作为铜绿假单胞菌pqs系统的信号分子,不仅能够调控许多毒力因子的表达,也能够影响一些微生物和宿主的多种生理过程。本文总结了PQS多种生物学功能,如介导QS系统、调控生物被膜形成、介导外膜囊泡产生及铁摄取、调节宿主免疫活性、介导细胞毒性作用,以及提供种群保护等。本文旨在突出铜绿假单胞菌PQS的功能多样性,并为PQS新功能研究和抗菌药物的研发提供指导。