Genome Evolution and Plasticity of Serratia marcescens, an Important Multidrug-Resistant Nosocomial Pathogen

Iguchi, Atsushi; Nagaya, Yutaka; Pradel, Elizabeth; Ooka, Tadasuke; Ogura, Yoshitoshi; Katsura, Keisuke; Kurokawa, Ken; Oshima, Koichiro; Hattori, Masahira; Parkhill, Julian; Sebaihia, Mohamed; Coulthurst, Sarah J.; Gotoh, Naomasa; Thomson, Nicholas R.; Ewbank, Jonathan J.; Hayashi, Tetsuya

doi:10.1093/gbe/evu160

Cited by 163 publications

(161 citation statements)

References 77 publications

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“…Second, deletion of the prtS gene was not sufficient to completely eliminate secreted protease activity by clinical isolate K904. These observations suggested the existence of other protease genes in the genome of S. marcescens, a prediction that was validated by searching the published genome of strain Db11 (44). Transcripts from each of the three ORFs could be detected in both a clinical and laboratory strain and were much higher in the clinical isolate, supporting the conclusion that they were not cryptic ORFs.…”

Section: Discussionmentioning

confidence: 61%

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

et al. 2015

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The Gram-negative bacterium and opportunistic pathogen Serratia marcescens causes ocular infections in healthy individuals. Secreted protease activity was characterized from 44 ocular clinical isolates, and a higher frequency of protease-positive strains was observed among keratitis isolates than among conjunctivitis isolates. A positive correlation between protease activity and cytotoxicity to human corneal epithelial cells in vitro was determined. Deletion of prtS in clinical keratitis isolate K904 reduced, but did not eliminate, cytotoxicity and secreted protease production. This indicated that PrtS is necessary for full cytotoxicity to ocular cells and implied the existence of another secreted protease(s) and cytotoxic factors. Bioinformatic analysis of the S. marcescens Db11 genome revealed three additional open reading frames predicted to code for serralysin-like proteases noted here as slpB, slpC, and slpD. Induced expression of prtS and slpB, but not slpC and slpD, in strain PIC3611 rendered the strain cytotoxic to a lung carcinoma cell line; however, only prtS induction was sufficient for cytotoxicity to a corneal cell line. Strain K904 with deletion of both prtS and slpB genes was defective in secreted protease activity and cytotoxicity to human cell lines. PAGE analysis suggests that SlpB is produced at lower levels than PrtS. Purified SlpB demonstrated calcium-dependent and AprI-inhibited protease activity and cytotoxicity to airway and ocular cell lines in vitro. Lastly, genetic analysis indicated that the type I secretion system gene, lipD, is required for SlpB secretion. These genetic data introduce SlpB as a new cytotoxic protease from S. marcescens. Microbial keratitis (MK) is a blinding disease with poor visual outcomes even with effective antibiotics and antifungal agents (1-3). In addition to being a major cause of hospital-acquired infections, such as ventilator-associated pneumonia (4, 5), Serratia marcescens is a common cause of MK (1, 2, 6-8), yet the virulence factors involved in this process are poorly understood. In general, bacterial secreted factors, including hemolysins and proteases, contribute to the pathogenesis of bacterial corneal infections (9-12). There are several studies characterizing the importance of proteases from S. marcescens isolates in ocular infections, most recently reviewed by Matsumoto (13). Serralysin is a cytotoxic factor capable of killing mammalian cells in vitro (14,15). Purified serralysin is sufficient to cause keratitis when injected into rabbit eyes and promotes the spread of bacteria through the corneal stroma (16-18). Additionally, serralysin can degrade components of the human immune system, such as PAR-2, in vitro, and this may impact corneal pathogenesis (13,(19)(20)(21). Serralysin, and serralysin family metalloproteases, such as alkaline protease from Pseudomonas aeruginosa, can proteolyze mammalian cell surface proteins, thereby modulating cell physiology. A recent example is the protease-mediated activation of the epithelial sodium channel, lea...

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Section: Discussionmentioning

confidence: 61%

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

et al. 2015

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“…Due to genomic plasticity of Enterobacteriaceae through lateral gene transfer, plasmid-encoding genetic determinants give rise to genetic and ecological diversity in this family of bacteria (Brisse andVerhoef, 2001, Iguchi et al, 2014a). Iguchi et al (2014b) characterized genetic diversity of Serratia spp., using complete genome sequences and found a remarkable intra-species genetic diversity, both at the sequence level and with regards to genome flexibility, which may reflect the diversity in members of this species. Brisse and Verhoef (2001) noted high degree of genetic heterogeneity and phylogenetic diversity of K. oxytoca from 120 clinical isolates using randomly amplified polymorphic DNA (RAPD)…”

Section: Hierarchical Cluster Analysismentioning

confidence: 99%

Characterization of Escherichia coli and other Enterobacteriaceae in producer-distributor bulk milk

Ntuli

Njage

Buys

2016

Journal of Dairy Science

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INTERPRETIVE SUMMARYCharacterization of E. coli and other Enterobacteriaceae in producer-distributor bulk milk, Ntuli, The direct sale of milk from producer-distributor (PD) to consumers is a common practice in many countries. We characterized E. coli and other Enterobacteriaceae in PD bulk milk sold at retail points in South Africa (SA). The study highlighted that there is a potential risk of transferring drug resistant pathogenic E. coli to consumers through the food chain.Information obtained from the study will be used to model the risk of pathogenic E. coli in PD milk and the proposal of most potentially effective mitigation efforts towards enhancing food security. ABSTRACTThe current study was undertaken to characterize Escherichia coli and other Enterobacteriaceae in raw and pasteurized producer-distributor bulk milk (PDBM). A total of 258 samples were collected from purchase points in 8 provinces in South Africa. The samples were tested for 1 antibiotic residues, phosphatase, total aerobic bacteria, coliforms and E. coli counts. Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used for identification of isolates. E. coli isolates were characterized for virulence factors, antimicrobial resistance, serotypes and presumptive E. coli O157:H7. Antibiotic residues and alkaline phosphatase were detected in 2 % (n=258) and 21 % (n=104) of the samples respectively. A total of 729 isolates belonging to 21 genera and 59 species were identified. E. coli, Enterobacter cloacae, Klebsiella oxytoca and Raoultella ornithinolytica were the most abundant species. Spoilage Enterobacteriaceae species exceeded 50 % of the total isolates. E. coli was detected and isolated from 36 % of the milk samples. Thirty one E. coli isolates harbored virulence genes stx1/stx2 and 38 % (n=121) were presumptive O157:H7. Prevalence of samples with presumptive shigatoxin producing E. coli (STEC) was 10 %. Antimicrobial resistant E. coli isolates were detected in 70 % of the milk samples with 36 % of stx1/stx2 positive E. coli showing multi-drug resistance. Information obtained from the study will be used for modelling the public health risk posed by milkborne pathogens in PDBM, which in many cases is consumed by the poor and vulnerable population.

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“…1B; also see Tables S3 and S4 in the supplemental material), corresponding to SMDB11_3958 and SMDB11_3959, respectively (ORF designations are based on the DB11 genome [36]), that are predicted to code for a two-component histidine kinase and a response regulator based on sequence.…”

Section: Identification Of Eepr and Eepsmentioning

confidence: 99%

Serratia marcescens Cyclic AMP Receptor Protein Controls Transcription of EepR, a Novel Regulator of Antimicrobial Secondary Metabolites

et al. 2015

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Serratia marcescens generates secondary metabolites and secreted enzymes, and it causes hospital infections and communityacquired ocular infections. Previous studies identified cyclic AMP (cAMP) receptor protein (CRP) as an indirect inhibitor of antimicrobial secondary metabolites. Here, we identified a putative two-component regulator that suppressed crp mutant phenotypes. Evidence supports that the putative response regulator eepR was directly transcriptionally inhibited by cAMP-CRP. EepR and the putative sensor kinase EepS were necessary for the biosynthesis of secondary metabolites, including prodigiosin-and serratamolide-dependent phenotypes, swarming motility, and hemolysis. Recombinant EepR bound to the prodigiosin and serratamolide promoters in vitro. Together, these data introduce a novel regulator of secondary metabolites that directly connects the broadly conserved metabolism regulator CRP with biosynthetic genes that may contribute to competition with other microbes. IMPORTANCEThis study identifies a new transcription factor that is directly controlled by a broadly conserved transcription factor, CRP. CRP is well studied in its role to help bacteria respond to the amount of nutrients in their environment. The new transcription factor EepR is essential for the bacterium Serratia marcescens to produce two biologically active compounds, prodigiosin and serratamolide. These two compounds are antimicrobial and may allow S. marcescens to compete for limited nutrients with other microorganisms. Results from this study tie together the CRP environmental nutrient sensor with a new regulator of antimicrobial compounds. Beyond microbial ecology, prodigiosin and serratamolide have therapeutic potential; therefore, understanding their regulation is important for both applied and basic science. In order for organisms to survive and prosper, they must be able to sense their environment and effectively compete with other organisms. To respond to these environmental changes, bacteria have developed elaborate transcriptional regulatory systems that enable fine-tuning of factors that allow for their adaptation and proliferation. One of the most studied signaling systems involved in adaptation to the nutritive status of the environment is the cyclic AMP (cAMP)-associated catabolite repression system (1-4). The second messenger cAMP has been classified as an alarmone that induces positive regulation of alternative carbon transport systems in times of carbon/fuel deprivation (5). In addition to catabolite repression control, this system also can positively regulate flagellum production in unfavorable conditions (6) and activate attachment factors in nutrient-rich conditions (7).Evidence suggests that cAMP-cAMP receptor protein (CRP) can directly bind to and promote expression of secondary metabolite genes involved in antibiotic production in Streptomyces coelicolor (2). A positive or negative role for cAMP has been suggested for control of antimicrobial production in other organisms, including fungi, although dire...

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Genome Evolution and Plasticity of Serratia marcescens, an Important Multidrug-Resistant Nosocomial Pathogen

Cited by 163 publications

References 77 publications

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens

Characterization of Escherichia coli and other Enterobacteriaceae in producer-distributor bulk milk

Serratia marcescens Cyclic AMP Receptor Protein Controls Transcription of EepR, a Novel Regulator of Antimicrobial Secondary Metabolites

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