Vibrio Species PDF

VIBRIO SPECIES Vibrio Optional reading: Page 401-430 Food microbiology : fundamentals and frontiers Author: Michael P Doyle & Robert Buchanan Publisher: Washington, DC American Society for Microbiology Press, ©2013 Available as an ebook from library. Vibrio sp. Vibrio is a nonspore-forming, Gramnega...

VIBRIO SPECIES Vibrio Optional reading: Page 401-430 Food microbiology : fundamentals and frontiers Author: Michael P Doyle & Robert Buchanan Publisher: Washington, DC American Society for Microbiology Press, ©2013 Available as an ebook from library. Vibrio sp. Vibrio is a nonspore-forming, Gramnegative, Vibrio shaped bacterium Within the Vibrio genus there are ~96 species, at least 12 species that are causative agents in human infection; however, most illness is caused by just 3 species: – Vibrio parahaemolyticus – Vibrio vulnificus – Vibrio cholera (more waterborne than foodborne infection) Vibrio sp. Environmental Microbiology Vibrio sp. is a predominant bacterial genus in estuarine waters Most Vibrio isolates, in each of the potentially pathogenic species, are non-pathogenic – However, a few strains in each of these species (V. cholerae, V. parahaemolyticus, and V. vulnificus) have picked up virulence factors which cause illness in humans Vibrio infection is generally associated with seafood consumption – Or with seafood contact Approximately 40-60% of the finfish and shellfish purchased at a supermarket contains a Vibrio spp. The number of vibrios in the water vary by water temperature, so there are definite spikes in the summer months Similarly, vibrios are more common in warmer waters With the exception of V. cholerae O1 or O139, vibrios in water are part of the natural microbiota of the water and not caused by fecal contamination – i.e. the fecal oral route does not apply to Vibrio Vibrio parahaemolyticus In the summer of 2015, 72 residents of the metro Vancouver area became sickened with symptoms such as diarrhea, abdominal cramping, fever, headache, nausea, and vomiting These residents had all eaten out within the two days preceding their illness (at different restaurants) Each sick person reported eating raw oysters The weeks preceding the outbreak had had record setting high temperature (this is a fact of life now) This is the most common Vibrio infection from Canadian seafood, when the water that oysters are harvested from goes above 17C it’s “Vibrio” season – Colder waters produce safer seafood (if only considering Vibrio infections) Vibrio parahaemolyticus V. parahaemolyticus is serotyped according to it’s LPS (O) antigen, and capsular polysaccharide (K) antigen – Will see regional differences in prevalence of serotypes, on the Canadian West Coast its O4:K12 Infections are almost exclusively linked to the consumption of raw or undercooked seafood A key feature is that V. parahaemolyticus has a generation time of 8 to 9 minutes at 37C, the ability to grow rapidly means that contaminated food becomes highly colonized if temperature abused Symptoms appear 4 to 30 hours after the ingestion of contaminated food Symptoms include diarrhea, abdominal cramps, nausea, vomiting, and fever Symptoms subside in 3 to 5 days Vibrio parahaemolyticus Broberg, CA., Calder TJ., and Orth K., Microbes, Infect. 2011 12(13):992-1001 Vibrio parahaemolyticus Pathogenic Vibrio parahaemolyticus produces three haemolytic toxins: a thermoliable haemolysin (tlh), a thermostable direct haemolysin (tdh), and thermostable direct-related haemolysin (trh) Most clinical isolates contain tdh and/or trh while very few environmental isolates contain tdh or trh The TDH and TRH toxins are secreted from the bacteria and form tetrameric pore complexes in the host membrane. These pores allow ions to flow freely across the host membrane which leads to hemolysis or cytotoxicity. V. parahaemolyticus translocates T3SS1 effectors (VopQ, VopR, VopS, and VPA0450) into host cells to cause cytotoxicity in different cell types such as macrophages and HeLa cells. T3SS1 is found in all V. parahaemolyticus isolates, even non-pathogenic isolates, indicating an important role in the environment T3SS2 effectors (VopA, VopC, VopL, and VopT) are translocated into host cells to cause cytotoxicity of colon epithelial cells or enterotoxicity within the host Broberg, CA., Calder TJ., and Orth K., Microbes, Infect. 2011 12(13):992-1001 Vibrio parahaemolyticus Broberg, CA., Calder TJ., and Orth K., Microbes, Infect. 2011 12(13):992-1001 Vibrio parahaemolyticus A single flagellum at one pole of the bacterium is required for swimming motility During growth in semi-solid media, flagella are produced along the lateral side of the bacterium, which aid in swarming motility MAM7 is a multivalent adhesion protein that binds to fibronectin and phosphatidic acid, which is required for the initial attachment to host cells As shown simplistically, V. parahaemolyticus can utilize the siderophores vibrioferrin, ferrichrome, and aerobactin, along with heme, to scavenge iron from the environment This is likely why it causes haemolysis – Every bacteria needs a source of iron These iron transporters are internalized by different membrane receptors on the outer membrane of the bacteria and transported to the cytoplasm by different ABC complexes Broberg, CA., Calder TJ., and Orth K., Microbes, Infect. 2011 12(13):992-1001 Type III Secretion Systems (T3SS) The T3SS is a major virulence factor that can inject a variety of effector proteins into host cells through a syringe-like transmembrane device T3SS1 is on chromosome 1 (found in environmental isolates, and clinical isolates) and T3SS2 is on chromosome 2 (found in clinical isolates) T3SS2 contributes to enterotoxcity, T3SS1 contributes to cytotoxicity – T3SS2 also is involved in the negative regulation of cellular inflammatory response – which is conducive to immune evasion TDH/TRH are on the T3SS2 regulon and are used as diagnostic markers of a virulent isolate Type III Secretion Systems (T3SS) Plaza, N et al., 2021. Identification of a Family of Vibrio Type III Secretion System Effectors That Contain a Conserved Serine/Threonine Kinase Domain. mSphere. 6(4) Research Project Plug While working at Health Canada I discovered several clinical isolates that lacked the T3SS2 as well as TDH/TRH A colleague in Mexico discovered several isolates like this as well There are two options – There are emerging virulence factors we don’t know about – These isolates are innocent bistanders to another Vibrio infection Why? Do they make it worse or support the infection Looking for students to help figure this out! Trip to Israel, trip to Mexico Type III Secretion Systems (T3SS) Regulation Li, L. et al., 2019. Molecular mechanisms of Vibrio parahaemolyticus pathogenesis. Microbiological Research (222) 43-51. Type III Secretion Systems (T3SS) Regulation The expression of T3SS2 is regulated by VtrA and VtrB VtrA is a transmembrane protein that forms a complex with VtrC that can form a barrel-like structure that can recognize and bind to bile salt Recognition of bile salt leads to expression of VtrB which then leads to the expression of T3SS2 genes Bile salt is a common up-regulator of important virulence genes in Vibrio and other gastrointestinal pathogens Type III Secretion Systems (T3SS) Effectors Wang R. et al., 2015. The pathogenesis, detection, and prevention of Vibrio parahaemolyticus. Frontiers in Microbiology (6)144 Type III Secretion Systems (T3SS) Effectors Effectors of T3SS2 destroy the cytoskeleton and manipulate cell signaling transduction. So far, 7 effectors have been found in T3SS2 (VopA, VopT, VopL, VopV, VopC, VopZ, and VPA1380) VopA and VopZ inhibit immune response by inhibiting different components of the mitogen-activated protein kinase (MAPKs) signaling pathway – VopA is an acetyltransferase that blocks MAPKs signaling, suppresses cell division, and leads to cell death – VopZ inhibits the activation of the TAK1 kinase, inhibition of TAK1 leads to epithelial cell damage, death, and inflammatory response VopC, VopL and VopV act on the cytoskeleton – VopC induces changes in the actin cytoskeleton that promotes intracellular invasion – VopV can bind actin and this is sufficient to cause diarrhea (it is primarily responsible for enterotoxicity) – VopL promotes actin bunding by binding to actin monomers VopT is an ADP ribosyltransferase that effects cellular metabolism leading to cytotoxicity VopL can also neutralize reactive oxygen species (ROS) and promote bacterial survival in host cells VPA1380 has cytotoxicity – but the mechanism is unclear, it works through cysteine metabolism Type VI Secretion Systems (T6SSs) V. parahaemolyticus also contains two T6SSs – T6SS1 is encoded on chromosome 1 and is found in clinical isolates – T6SS2 is encoded on chromosome 1 and found in both clinical and environmental isolates – it is active under low-salt conditions T6SSs are known to mediate antibacterial activity and are involved in antagonistic interbacterial interactions (in the environment and in the microbiome) Vibrio vulnificus Day 1: A 45-year-old male with a history of end-stage liver disease (caused by alcoholism and hepatitis C infection) went to the hospital with a primary complaint of “my legs are hurting” – The pain was described as a sudden onset of an intense burning sensation from both feet to the upper thighs – Did not report any trauma – He had minor scratches on his knees – He reported eating raw oysters two days prior The pain started the night before and was associated with a high fever, vomiting, and labored breathing – He had no complaints of chills, nausea, cough, diarrhea, dysuria, abdominal pain, or chest pain. Later on he developed a microvascular petechial rash on his legs The rash on his legs progressed then to dark, fluid-filled bullous lesions Day 2: Patient went into cardiac arrest twice, after first he was successfully resuscitated, he died after the second. Story Taken From: Kumamoto, Kenneth S., and David J. Vukich. "Clinical infections of Vibrio vulnificus: a case report and review of the literature." The Journal of emergency medicine 16.1 (1998): 61-66. Vibrio vulnificus Vibrio vulnificus Most serious vibrio infection, responsible for 95% of seafood related deaths in North America Are not serotyped, but are divided into 3 biotypes based on biochemistry – Biotype 1 causes disease in humans – Biotype 2 causes disease in eels, and rarely in humans – Biotype 3 is a hybrid of biotype 1 and 2 and is found only in Israel There are two distinct V. vulnficus syndromes – The first is a primary septicemia caused by consuming raw or undercooked seafood – The second is a necrotizing wound infection which results from an open wound being exposed to warm seawater, or contaminated seafood, with high concentrations of V. vulnificus Primary septicemia cases resulting from raw oyster consumption have fatality rates of 60% Can also cause wound infections from handling contaminated seafood with cuts or scratches (20-25% fatality rate) – Surgery may be required to clean infected tissue – Some cases require amputation Only isolated from warm waters Symptoms can appear 7 hours to several days after exposure Symptoms include fever, chills, nausea, and hypotension Vibrio vulnificus Risk Factor Patients with Primary Septicemia Consumption of Raw Oysters (in the week before becoming ill) 96% Wound exposure to seawater or seafood (in the week before becoming ill) Patients with a Wound Infection 100% Any chromic disease 97% 68% Liver disease 80% 22% Alcoholism 65% 32% Diabetes 35% 20% Malignancy 17% 10% Renal Disease 7% 7% Table Modified From: Bross, Michael H., et al. "Vibrio vulnificus Infection: Diagnosis and Treatment." Alcoholism 65 (2007): 32. Vibrio vulnificus Virulence factors are poorly understood, but are known to include: – The polysaccharide capsule (K-antigen) is required If cells loose the K-antigen they loose virulence The role in virulence is not understood – LPS (O-antigen) The high fever, systemic infection, and shock are consistent with LPS induced endotoxic shock – vvhA A heat-stable haemolysin/cytotoxin that is unique to V. vulnificus and likely plays a role in virulence Vibrio cholerae On 12 January 2010, a magnitude 7.0 earthquake, centered near Port-auPrince, struck Haiti and resulted in infrastructure damage including crippled sanitation systems that contributed to a devastating cholera outbreak starting in October According to the Pan American Health Organization, this outbreak, which is still ongoing, has sickened 750,000 Haitians and killed 9,068 to date In the first few weeks of the outbreak, the U.S. CDC analyzed the strain by PFGE and evidence suggested that the etiological strain originated in South Asia and was probably brought to the region by United Nations (UN) workers However, several argued that this was not conclusive, as PFGE does not yield a detailed enough fingerprint for such a conclusion The main challenge in Vibrio outbreak source tracing is that the most common PFGE patterns tend to drift over the course of an outbreak, indicating that multiple concurrent outbreaks may be occurring, a possibility that, in this case, also challenged the singlesource introduction hypothesis Text modified from: Ronholm, J., et al. "Navigating Microbiological Food Safety in the Era of Whole-Genome Sequencing." Clinical Microbiology Reviews 29.4 (2016): 837-857. Haitian Cholera Outbreak Temporally concurrent matching patterns came from: – – – – – – – Figure – Talkington et al., 2011 EID 17(11) 2122-2129. Afghanistan Cameroon India Nepal Oman Pakistan South Africa Haitian Cholera Outbreak Figure – Frerichs et al., 2012 Bacteriology 18 E158-E163 Haitian Cholera Outbreak Figure – Hendriksen et al., 2011 mBio 2(4)e00157-11. Vibrio cholerae Yemin Outbreak 26 October 2017 – The Ministry of Public Health and Population of Yemen has reported a cumulative total of 862858 suspected cases of cholera including 2177 associated deaths as of 26 July for the outbreak which started in October 2016. The overall case-fatality rate remains low (0.25%). There has been a modest decrease in the number of suspected cholera cases and deaths compared to previous weeks, and the overall trend appears to be stable. While cholera is endemic in Yemen, the country has experienced a surge in cholera cases since April this year, with nearly 5000 cases reported per day. Ongoing conflict, destroyed health, water and sanitation infrastructure and malnutrition have caused the people to be more vulnerable to diseases, including cholera and other endemic infectious diseases. http://www.cnn.com/2017/12/21/health/yemen-cholera-intl/index.html Vibrio cholerae Serotyping of V. cholerae is based only on the LPS (O) antigen V. cholerae O1 and O139 are one of the few foodborne illness which is known to cause epidemics and pandemics These two strains produce cholera toxin (CTX) During epidemics fecal contamination of the water is a source of other illnesses Periodically, O1 and O139 environmental isolates cause illness in the US Gulf coast and Australia in uncooked seafood This is generally not an issue in Canadian seafood, our waters are too cold – Occasionally, we see it in travellers returning from abroad V. cholerae V. cholerae has a VBNC state, where cells are reduced in size and become ovoid VBNC cells are not culturable on any media, however, when injected into rabbits they cause ileal loop fluid accumulation Patients who recover from infection without antibiotics excrete V. cholerae for 1-2 weeks in their feces V. cholerae colonizes the small intestine using adherence factors It produces CTX which disrupts the ion transport, this lease leads to severe diarrhea The CTX toxin is carried on a phage, only V. cholerae which are infected with this phage are able to cause illness in humans Vibrio cholerae Figure taken from: http://ib.bioninja.com.au/options/option-d-human-physiology/d2-digestion/digestive-infections.html Vibrio cholerae V. cholerae releases Cholera Toxin (CTX) that binds to ganglioside receptors on the surface of intestinal epithelium cells CT is internalized by endocytosis and triggers the production of cyclic AMP (a second messenger) within the cell Cyclic AMP (cAMP) activates specific ion channels within the cell membrane, causing an efflux of ions from the cell The build up of ions in the intestinal lumen draws water from cells and tissues via osmosis – causing acute diarrhea As water is being removed from body tissues, dehydration will result if left untreated – This can be fatal if left untreated for long enough Information taken from: http://ib.bioninja.com.au/options/option-d-human-physiology/d2-digestion/digestive-infections.html Vibrio genomics Vibrio has highly fluid and plastic genomes V. parahaemolyticus carries the genes for its K and O antigens in two discrete clusters, which can rapidly undergo horizontal gene transfer – Therefore V. parahaemolytics has been known to switch serotypes mid-outbreak V. cholerae becomes naturally competent when it is grown on chitin (i.e. crustacean shells) and readily takes up DNA from the environment – This increases it’s chance of taking up genes that increase its survival and virulence V. cholerae needs to be infected with a phage to be virulent – It’s happened twice, it will likely happen again – Climate change increases the probability that this will happen Vibrio genomics Okada et al.,2009. Infection and Immunity Vibrio genomics Somewhere in it’s evolutionary history two serotypes of V. cholerae O1 and O139 acquired the CTX toxin and is now able to cause cholerae – O1 acquired it first, O139 only recently acquired this gene (around 1992) All other serotypes of V. cholerae that did not acquire this gene are nonpathogenic, and do not cause illness in humans In the evolutionary history of V. parahaemolyticus two different routes to virulence occurred, one was the acquisition of tdh and the other was the acquisition of trh but there is every indication that these genes routinely move between V. parahaemolyticus genomes – They sometimes even move to V. alginolyticus genomes V. parahaemolyticus isolates without these genes do not cause illness (probably) The T3SS also plays a role in V. parahaemolyticus virulence though its exact role is still unclear – The T3SS sometimes gets transferred from V. parhaemolyticus to V. cholerae however, when this happens it makes V. cholerae pathogenic to humans, although, the symptoms of illnesses caused by these strains are more inline with a V. parahaemolyticus infection than with a V. cholerae infection Prevention of Vibrio Infection Vibrios are sensitive to cold, seafood should always be frozen, refrigerated, or stored on ice, and should be eaten fresh Cooking is very effective at eliminating vibrios Irradiation and high hydrostatic pressure kills pathogenic vibrios A variety of dried spices, herbal oils, tomato sauce, and organic acids (lemon juice) all have bactericidal activity Depuration (the process by which filter-feeding bivalves are purified by pumping through clean water) removes Salmonella and E. coli but not Vibrio Comparison of Infectious Vibrios V. parahaemolyticus V. vulnficus V. cholerae Environment Cool water but warmer than 15C Warm water Tropical water Symptoms of Infection Diarrhea, Fever, Abdominal Cramps, Nausea, Vomiting Fever, Chills, Nausea, Skin Lesions Rice water stools (pale gray colour), Abdominal pain, Loss of appetite Mortality Rate Very low 40-60% ~ 1% in worse case scenarios Virulence Factors tdh and trh Capsule, LPS, vvhA Cholerae toxin (CTX) Review of Vibrio species There are several vibrio species which are natural to marine environments and estuaries Three of these species are a common cause of seafood borne illness – Vibrio parahaemolyticus – Vibrio vulnificus – Vibrio cholerae Although these three species cause illness, most isolates from each species are non-pathogenic, though some have acquired virulence factors through gene horizontal transfer V. parahemolyticus is mainly associated with occasional outbreaks related to the consumption of raw or undercooked seafood V. vulnificus can cause a foodborne infection or a skin infection, both of which are very serious and have a high case fatality rate, but both of which are very rare V. cholerae causes large and sustained epidemic and pandemic outbreaks, but mostly in the tropical developing world The most likely cause of illness in Canadian harvested seafood is V. parhaemolyticus