ABSTRACT
Plesiomonas shigelloides (a bacterium widely distributed in aquatic ecosystems causing both intestinal and extra-intestinal diseases) shows a host of putative virulence markers, such as hemolysins, cytotoxins, production of exoenzymes associated with pathogenicity, adhesive ability and vacuolation of cell lines in vitro. Technical difficulties in detecting some of these virulence factors together with scantiness of epidemiological information, due to the lack of routine analysis for P. shigelloides as etiological agent of gastroenteritis, lead to sporadic and occasional finding of these bacteria. All this casts doubt on the real virulence potential of P. shigelloides and fuels a debate about assignment of these bacteria to the list of human pathogens. Here we demonstrated the phenotypic diversity and the putative virulence markers by examining serotype biochemical and virulence properties of 60 strains of P. shigelloides isolated from human, animal and environmental samples in different countries, which showed the unpredictable occurrence of the above properties depending on various locations and diverse sources.
Subject(s)
Environmental Microbiology , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/veterinary , Plesiomonas/physiology , Virulence Factors/metabolism , Animals , Bacterial Typing Techniques , Humans , Plesiomonas/genetics , Plesiomonas/isolation & purification , SerotypingABSTRACT
To study molecular mechanisms underlying self-defense of the bacterial pathogen Plesiomonas shigelloides against host inflammatory and immune responses, we evaluated its interactions with mammalian papain-like cathepsins that are essential for host immunity. When grown under anaerobic, but not aerobic, conditions, P. shigelloides was shown to bind and inhibit papain, a model representative of the papain family of cysteine proteinases. This points to mammalian cathepsins as likely physiological targets of a novel cysteine-proteinase inhibitor expressed on bacterial cell surface. Both papain and mammalian cathepsins L and B were inhibited by periplasmic extracts of aerobically and anaerobically grown bacteria, the inhibitory activity being higher in the latter. Inhibition by both intact cells and periplasmic samples was rapid and efficient. The results suggest a possible defensive role of bacterial inhibitors of cathepsins during invasion of a mammalian host. The bacteria thus may modulate host protective responses through inhibiting cathepsins involved in antigen processing and presentation.
Subject(s)
Cathepsin B/antagonists & inhibitors , Cathepsins/antagonists & inhibitors , Cysteine Proteinase Inhibitors/metabolism , Papain/antagonists & inhibitors , Plesiomonas/pathogenicity , Animals , Antigen Presentation , Antigens, Bacterial , Cathepsin L , Cysteine Endopeptidases , Cysteine Proteinase Inhibitors/pharmacology , Humans , Mammals , Periplasm/metabolism , Plesiomonas/immunology , Plesiomonas/metabolismABSTRACT
Serotyping and some potential virulence-associated markers were investigated in Plesiomonas shigelloides strains isolated from humans, animals and aquatic environments. Surface properties of these strains were evaluated using Congo red binding, salt-aggregation test, bacterial adherence to xylene and motility. Production of pancreatic elastase, proteinase (consistent with subtilisin Carlsberg), triacylglycerol lipase, histidine decarboxylase and beta-hemolysin was also determined. In addition, detection of signal molecules such as C4-C8 unsubstituted N-acylhomoserine lactones (AHLs) was performed. The serological typing of the P. shigelloides strains showed that the isolates belonged to 13 different serovars. The majority of the strains were hydrophobic and motile. The strains produced low levels of elastase, proteinase and histidine decarboxylase whereas triacylglycerol lipase activity was relatively high. Only 23.3 % of the strains produced hemolysin. The AHLs signal molecules were not detected. P. shigelloides strains were able to produce a variety of potential virulence markers which may be involved in the pathogenesis of Plesiomonas-associated infections.
Subject(s)
4-Butyrolactone/analogs & derivatives , Plesiomonas/pathogenicity , 4-Butyrolactone/metabolism , Animals , Bacterial Adhesion , Gram-Negative Bacterial Infections/microbiology , Hemolysin Proteins/biosynthesis , Histidine Decarboxylase/biosynthesis , Humans , Lipase/biosynthesis , Pancreatic Elastase/biosynthesis , Plesiomonas/classification , Plesiomonas/isolation & purification , Plesiomonas/metabolism , Serotyping , Species Specificity , Virulence , Water MicrobiologyABSTRACT
We evaluated the random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) techniques for studying an outbreak of beta-haemolytic streptococci group A (GAS) occurred at two maternity wards at Danderyd hospital, Stockholm, Sweden. All the isolates were of T-type 8,25. The RAPD technique revealed that all RAPD-PCR profiles were identical. PFGE showed that all the patterns but one were identical. These patterns were compared with 10 different T-type GAS from the strain collection of the Swedish Institute for Infectious Disease Control (SMI) and T-type 8,25 from different years and locations. The SMI strains exhibited patterns different from each other and all different from the isolates from Danderyd hospital. Moreover, RAPD could not differentiate among the T-type 8,25 isolates from different years and locations but PFGE showed differences among the amplicons. Our results indicated that the RAPD and PFGE techniques could be efficient tools in epidemiological studies of GAS.
Subject(s)
Cross Infection/epidemiology , Disease Outbreaks , Electrophoresis, Gel, Pulsed-Field/methods , Random Amplified Polymorphic DNA Technique/methods , Streptococcal Infections/epidemiology , Streptococcus pyogenes/isolation & purification , Cross Infection/microbiology , DNA, Bacterial/analysis , DNA, Bacterial/isolation & purification , Female , Hospitals, Maternity , Humans , Pregnancy , Sensitivity and Specificity , Streptococcal Infections/microbiology , Streptococcus pyogenes/classification , Streptococcus pyogenes/genetics , Sweden/epidemiologyABSTRACT
Twenty-five strains of Plesiomonas shigelloides isolated from aquatic environment, 10 strains from human cases of diarrhoea and five strains from animals were identified by the polymerase chain reaction technique based on 23S rRNA gene. For this purpose, two primers targeted against part of the 5' half of the 23S rRNA gene of P. shigelloides (Escherichia coli number C-912, G-1195; Plesiomonas number C-906, G-1189) were designed. Results from our study indicated that this method might serve as a tool for a rapid and sensitive identification of P. shigelloides from different environmental and clinical sources.
Subject(s)
Diarrhea/microbiology , Fresh Water/microbiology , Plesiomonas/isolation & purification , Polymerase Chain Reaction/methods , RNA, Ribosomal, 23S/genetics , Water Microbiology , Animals , Base Sequence , DNA Primers , Gram-Negative Bacterial Infections/microbiology , Humans , Plesiomonas/classification , Plesiomonas/genetics , Sensitivity and Specificity , Sequence Alignment , SerotypingABSTRACT
Isolation and characterisation of Plesiomonas shigelloides from fresh water in Northern Europe is reported in this study. The organisms were isolated from two lakes and a river in Sweden. All isolates of P. shigelloides showed an identical biochemical profile and belonged to different serotypes, namely, O18, O23, O26, O58 and O60. The study indicates that P. shigelloides may occur in the aquatic environment of cold climates and as a result, it is likely to be associated with human infections caused by waterborne pathogens in geographical areas with similar climatic conditions.
