Presence of pathogenic Vibrio parahaemolyticus strains in mussels from the Adriatic Sea, Italy

Samples of mussels (Mytilus galloprovincialis) collected from approved coastal sites located on the Adriatic Sea (Central Italy) were examined for the presence of Vibrio parahaemolyticus and the occurrence of pathogenic strains. The isolation of the micro-organisms was performed using a standard method. A biochemical protocol was applied for the identification of the isolates. Polymerase chain reaction (PCR) was used to confirm the identification of the strains and to detect the tdh and trh genes. The Kanagawa phenomenon was assayed as phenotypic marker of thermostable direct hemolysin (TDH) toxin. The urease activity was assayed as phenotypic marker of trh gene. The protease activity and the cytotoxicity of strains were examined to identify other potential virulence factors. Thirty-five V. parahaemolyticus strains were isolated out of 144 samples. The tdh and trh genes were in one and three isolates, respectively. All strains, independent of the presence of tdh and trh genes, showed protease activity and cytotoxicity. Due to the occurrence of pathogenic V. parahaemolyticus, the potential risk of eating raw or undercooked mussels is envisaged.     

Isolation and molecular characterization of Vibrio parahaemolyticus from fresh, low-temperature preserved, dried, and salted seafood products in two coastal areas of eastern China

A total of 1293 seafood samples from fishing farm, retail markets, restaurants and cooking rooms of hotels in Jiangsu province and Shanghai city of China were collected and analyzed for the prevalence of Vibrio parahaemolyticus during July to October in 2007. Two hundred and fifty one isolates of V. parahaemolyticus were identified, of which 8 isolates were positive for tdh and 2 were positive for trh gene. Three tdh positive isolates were identified from low-temperature preserved seafood samples and 5 isolates from fresh seafood samples, of these tdh positive isolates, 3 were positive in ORF8-PCR test. The genetic diversity among V. parahaemolyticus isolates was assessed using random amplified polymorphic DNA (RAPD)-PCR and the results showed that there were 33 different genetic patterns that were clustered into nine groups (groups A to I) at 82% similarity level. About 31.9% of the isolates belong to type III9d that were widely distributed in fresh, iced, frozen, dried and salted seafood samples. Seven tdh positive isolates belonged to group A and one belonged to group C, 2 trh positive isolates were type I10d belonging to group F, which was identical to that of reference strains isolated from patients. This study demonstrated genetic variability within V. parahaemolyticus isolates from seafood in Chinese markets and confirmed the presence of toxigenic V. parahaemolyticus not only in fresh but also in iced and frozen seafood products indicating that low-temperature preserved seafood might be also a vehicle for transmitting pathogenic V. parahaemolyticus.     

Prevalence and population analysis of Vibrio parahaemolyticus in retail aquatic products from the southern Fujian coast,China

Vibrio parahaemolyticus is one of the most hazardous pathogens causing seafood-borne diseases in the southern Fujian coast, China. From June to October 2016, a total of 250 samples were collected from retail markets in the Xiamen, Quanzhou, and Zhangzhou regions. Seventy-seven V. parahaemolyticus isolates were identified using polymerase chain reaction (PCR). Then, molecular typing was performed using repetitive extragenic palindromic-PCR (REP-PCR). The distribution of seven virulence genes was detected by PCR. In aquatic products, the prevalence of V. parahaemolyticus was 30.8%, and the prevalence of tdh⁺ and trh⁺ was 2.6 and 1.3%, respectively. The prevalence of type III secretion system-2 (T3SS2) and the ureC gene was 5.2 and 3.9%, respectively. All 77 strains and the reference strain V. parahaemolyticus ATCC 17802 were classified into seven molecular types using REP-PCR. Thus, our findings demonstrated that the prevalence of V. parahaemolyticus was severe in the southern Fujian coast and that the regulations for aquatic food safety should be strengthened.     

Development of monoclonal antibody based sandwich ELISA for the rapid detection of pathogenic Vibrio parahaemolyticus in seafood

Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) are considered important virulence factors of Vibrio parahaemolyticus and strains producing either of these or both are considered pathogenic. In this study, we generated monoclonal antibodies (mAbs) against purified TRH recombinant protein of pathogenic V. parahaemolyticus. Sandwich enzyme-linked immunosorbent assays (ELISA) using the hybridoma clone 4B10 showed higher sensitivity of detection compared to other clones. Using mAb 4B10 based sandwich ELISA, we could detect pathogenic V. parahaemolyticus in 41.18% (14 out of 34) of the seafood samples analyzed. PCR targeting the toxR gene showed the presence of V. parahaemolyticus in 64.7% (22 out of 34) seafood samples. Further, PCR targeting the virulence genes showed that 6 seafood samples harboured the tdh gene while 9 harboured the trh gene indicating the presence of pathogenic V. parahaemolyticus. Our results show that mAb 4B10 sandwich ELISA developed in this study could be used as a rapid method for screening seafood samples for the presence of pathogenic V. parahaemolyticus.     

Occurrence and distribution of Vibrio parahaemolyticus in retail oysters in Sao Paulo State, Brazil

Vibrio parahaemolyticus is a potentially pathogenic bacterium that occurs naturally in estuarine environments worldwide, and is often associated with gastroenteritis in humans following consumption of raw bivalve mollusks, especially raw oysters. The occurrence of total and pathogenic V. parahaemolyticus in 74 samples of raw oysters collected in restaurants, supermarkets, groceries and beach huts in Sao Paulo State, was monitored between February 2006 and January 2007. Enumeration of V. parahaemolyticus was performed according to the most probable number (MPN) procedure. Five to ten typical colonies were selected from thiosulfate-citrate-bile salts-sucrose (TCBS) agar plates for confirmation by the presence of the species-specific gene tlh and the virulence genes tdh and trh by multiplex PCR. V. parahaemolyticus was detected in 100% of samples. The densities of total V. parahaemolyticus varied from 1.78 to 6.04 log₁₀ (MPN/g), with higher densities being detected in fall and summer, and lower densities in winter (P < 0.05). There was no statistical difference among densities of V parahaemolyticus regarding the site of collection. None of the 1943 V. parahaemolyticus isolates contained tdh and/or trh. These data provide information for the assessment of exposure to V. parahaemolyticus in oysters consumed in Sao Paulo, State, Brazil.     

Detection and molecular characterization of Vibrio parahaemolyticus isolated from seafood harvested along the southwest coast of India

The levels of total and tdh⁺ Vibrio parahaemolyticus were estimated in 83 seafood samples from southwest coast of India by colony hybridization. Conventional enrichment and isolation technique was also used to study the prevalence. Polymerase chain reaction (PCR) was performed on bacterial cell lyates for detection of total and pathogenic V. parahaemolyticus by amplification of specific genes. Of 83 samples tested, V. parahaemolyticus could be detected in 74 (89.2%) samples and tdh⁺ V. parahaemolyticus in 5 (6.0%) samples by colony hybridization. V. parahaemolyticus was detected in 68 (81.9%) of 83 samples after 18 h of enrichment by PCR, and isolated from 63 (75.9%) of 83 samples by conventional isolation. The virulence genes tdh and trh could be detected in 8.4% and 25.3%, respectively, in the sample enrichment broths by PCR. Use of colony hybridization following enrichment to achieve sensitive detection of tdh⁺ V. parahaemolyticus in seafood was evaluated using another set of 58 seafood samples. Thirty pathogenic V. parahaemolyticus strains isolated during the study were screened by PCR for genetic markers to be specific for the detection of the pandemic clone. Results of this study suggest that the GS-PCR may serve as a reliable genetic marker for the pandemic clone of V. parahaemolyticus.     

Incidence and Molecular Typing of Vibrio parahaemolyticus from Tiger Shrimp Culture Environments along the Southwest Coast of India

Vibrio parahaemolyticus is one of the most prevalent food-borne pathogens along the southwest coast of India, where marine foods are frequently consumed. Shrimp (Penaeus monodon) and environmental samples were collected from aquaculture farms located in and around Cochin. Confirmation of the biochemically identified strains with species-specific toxR gene and detection of virulent genes viz., tdh and trh was performed by polymerase chain reaction (PCR). The phenotypic markers for the presence of tdh and trh genes were assayed by Kanagawa phenomenon and urease activity, respectively. Protease activity was examined to identify other potential virulence factors. After phenotypic characterization of bacterial strains fingerprinting of genomic DNA was carried by various typing methods, viz., random amplified polymorphic DNA (RAPD), enterobacterial repetitive intergenic consensus sequence (ERIC), repetitive extragenic palindromic sequence (REP), and ribosomal gene spacer sequence (RS) PCR methods to assess the genetic diversity within the isolates. Eighteen percent of the samples were found positive for the incidence of V. parahaemolyticus by biochemical protocols and toxR (368 bp) targeted PCR. PCR analyses revealed 1% of the samples positive for tdh (269 bp) and trh (500 bp) gene. RAPD analysis revealed clustering of toxigenic strains into a single group. Cluster analysis revealed the conglomeration of isolates into two, five, and seven major groups using RS, ERIC, and REP PCR methods, respectively. RS PCR generated fewer amplified bands compared to REP and ERIC PCR methods, thus giving scope for higher discrimination. Moreover, RS PCR patterns were more discernible visually from other patterns, suggesting RS PCR as a considerably practical method for routine use.     

Multi-Loci Gene Sequencing and Identification of Bifidobacteria Strains Isolated from Dairy and Pharmaceutical Sources in South Africa

The 16S rRNA gene sequence analysis of Bifidobacterium species reveals high interspecies sequence similarity in the range of 87.7–99.5%. This study illustrated the extent of superiority of a multigenic approach, involving protein-coding genes, in comparison to the 16S rRNA gene, to precisely delineate presumptive Bifidobacterium isolates obtained from probiotic milk beverages, culture collections and pharmaceutical probiotic preparations. Oligonucleotide pairs PurF-rev/PurF-uni; RpoC-uni/RpoC-rev; DnaB-uni/DnaB-rev; DnaG-uni/DnaG-rev; and ClpC-uni/ClpC-rev amplified housekeeping genes while 27F/1492R amplified the 16S rRNA gene of the presumptive bifidobacteria in a polymerase chain reaction. Sequences of 16S rRNA gene and some protein-coding genes effectively identified the isolates. Phylogenetic analysis together with concatenation showed that clpC, purF and dnaG genes had over 8-fold better discriminatory power than the 16S rRNA gene in discriminating between Bifidobacterium isolates. However, phylogenetic analysis involving dnaB and rpoC gene sequences or their concatenated trees showed discrepancies in clustering isolates with designated type strains.     

Diverse Profiles of N‐acyl Homoserine l‐Lactones,Biofilm, Virulence Genes and Integrons in Food‐Borne Aeromonas Isolates

Aeromonas are regarded as opportunistic as well as primary pathogens of humans and fish, and are associated with gastroenteritis and septicemia in humans. Production of N‐acyl‐homoserine lactone (AHL) signal molecules and biofilm was determined in 22 Aeromonas isolates, from different food products in India, using thin‐layer chromatography (TLC) analysis and microtiter‐plate assay, respectively. Overall, highly heterogeneous patterns of AHL production were observed, with the production of N‐butanoyl homoserine lactone (C4‐HSL) and N‐hexanoyl homoserine lactone (C6‐HSL) by the majority (81.8%) of Aeromonas food isolates. Moreover, putative N‐pentanoyl homoserine lactone (C5‐HSL), N‐heptanoyl homoserine lactone (C7‐HSL), and N‐octanoyl homoserine lactone (C8‐HSL) were produced by 72.7%, 27.3%, and 9.1% of isolates, respectively. This is the 1st report of production of C7‐HSL by Aeromonas species. Aeromonas food isolates were highly variable in their biofilm forming abilities with majority of them as weak biofilm producers in 2 different media, TSB and M9 minimal medium supplemented with 0.4% glucose. The genes encoding for putative virulence factors, glycerophospholipid cholesterol acyltransferase (gcat), heat‐labile cytotonic enterotoxin (alt), heat‐stable cytotonic enterotoxin (ast), serine protease (ser), polar flagella (fla), and lateral flagella (lafA) were present in 95.5%, 59.1%, 22.7%, 81.8%, 77.3%, and 22.7% of the strains, respectively. Class 1 integrons (100 to 3000 bp) were found in 68.2% of food isolates; whereas, 50% isolates contained class 2 integrons (150 to 1600 bp). This study provides a baseline data on the diversity of AHLs, biofilm forming ability and presence of virulence genes and integrons in Aeromonas food isolates from India.     

Prevalence of Vibrio parahaemolyticus in seafoods and their processing environments as detected by duplex PCR

A duplex polymerase chain reaction (PCR) procedure targeting the genes gyrB and tl was established for specific identification of Vibrio parahaemolyticus from seafoods and processing environments. It could detect as few as 2.5 × 10² colony‐forming units mL^?1 in pure cultures. Direct detection of V. parahaemolyticus was also possible from artificially contaminated shrimp samples if combined with proteinase treatment. The homogeneous colonies on thiosulfate/citrate/bile salts/sucrose agar suspected to be V. parahaemolyticus or closely related species (n = 37) out of 259 samples of seafoods and processing environments were identified using the conventional method and duplex PCR. Both methods identified 17 isolates as V. parahaemolyticus from among the suspected isolates. Only one of the 17 V. parahaemolyticus isolates possessed the thermostable direct haemolysin gene (tdh) fragment as detected by different primer pairs in single PCR. Copyright © 2006 Society of Chemical Industry     

Validation of high pressure processing for inactivating Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas)

This study identified and validated high hydrostatic pressure processing (HPP) for achieving greater than 3.52-log reductions of Vibrio parahaemolyticus in the Pacific oysters (Crassostrea gigas) and determined shelf life of processed oysters stored at 5 °C or in ice. Raw Pacific oysters were inoculated with a clinical strain of V. parahaemolyticus 10293 (O1:K56) to levels of 10^4-5 cells per gram and processed at 293 MPa (43 K PSI) for 90, 120, 150, 180 and 210 s. Populations of V. parahaemolyticus in oysters after processes were analyzed with the 5-tube most probable number (MPN) method. Negative results obtained by the MPN method were confirmed with a multiplex PCR detecting genes encoding thermolabile hemolysin (tl), thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh). A HPP of 293 MPa for 120 s at groundwater temperature (8 ± 1 °C) was identified capable of achieving greater than 3.52-log reductions of V. parahaemolyticus in Pacific oysters. Oysters processed at 293 MPa for 120 s had a shelf life of 6-8 days when stored at 5 °C or 16-18 days when stored in ice. This HPP can be adopted by the shellfish industry as a post harvest process to eliminate V. parahaemolyticus in raw oysters.     

Incidence and Enumeration of Vibrio parahaemolyticus in Shellfish from Two Retail Sources and the Genetic Diversity of Isolates as Determined by RAPD-PCR Analysis

A total of 83 shellfish samples from two local retail sources (A and B) yielded 38 samples positive for the presence of Vibrio parahaemolyticus based on 3 tube MPN enrichments and isolation from thiosulfate-citrate-bile salts-sucrose agar (TCBS) and biochemical tests. The 38 positive samples yielded 133 biochemically presumptive isolates of V. parahaemolyticus. Among these 133 presumptive isolates, 104 were confirmed by the polymerase chain reaction (PCR), which yielded more reliable identification results than the biochemical tests. The 38 biochemically presumptive samples yielded 29 samples that were confirmed by PCR to be positive for the presence of V. parahaemolyticus. RAPD analysis with three random primers was performed to examine the genetic diversity of 64 strains among the PCR confirmed V. parahaemolyticus isolates from both retail sources. 52 of 56 composite RAPD types consisted of single strains, indicating that most of the V. parahaemolyticus isolates were genetically quite heterogeneous. No strains representing the same RAPD type occurred in both retail outlets, implying that contamination of the shellfish by V. parahaemolyticus from the 2 retail sources was from different environmental locals and shellfish harvesting areas. Eight genomic clusters were generated at the 25% similarity level in a dendrogram based on RAPD profiles. With few exception, isolates with close genetic relationships grouping into an individual cluster tended to be derived from the same retail source.     

Vibrio parahaemolyticus,a Notably Lethal Human Pathogen Derived From Seafood: A Review of its Pathogenicity,Characteristics, Subspecies Characterization,and Molecular Methods of Detection

Vibrio parahaemolyticus is a gram-negative enteropathogenic marine Vibrio that is capable of causing mild gastroenteritis to severe debilitating dysentery. Infections of the G.I. tract are usually due to consumption of raw shellfish. In addition, extraintestinal infections have been reported to be due to the organism such as eye and ear infections, and wound infections of the extremities. Virulence has been found to be associated with two principle genes that code for (1) a thermally stable direct acting hemolysin (tdh) and (2) a thermally stable direct acting–related hemolysin (trh) that is thermally lable. Virulent strains are usually characterized as Kanagawa Phenomenon (KP) positive which refers to β-hemolysis on a special blood agar known as Wagatsuma blood agar. Epidemiological studies have indicated that specific clones of certain serotypes, notably 03:K6 having enhanced virulence have become endemically established in certain global locals.     

Real-time PCR von virulenten Vibrio parahaemolyticus in Fisch- und Krebstierprodukten

Pathogenic V. parahaemolyticus strains cause gastroenteritis. Contaminated fi sh products and seafood represent the most important sources of infection. V. parahaemolyticus strains from patients differ from environmental isolates by their production of the haemolysins TDH and TRH that represent their main virulence factors. 710 specimens of fish and crayfish products were examined by an evaluated PCR-/real-time PCR. This detection method of virulent V. parahaemolyticus isolates reduces the working time by one day after a selective enrichment of vibrios with alkaline saline peptone water.     

A review of the current status of cultural and rapid detection of Vibrio parahaemolyticus

Vibrio parahaemolyticus is ubiquitous in estuarine environments and can be commonly found in seafood products. This bacterial pathogen continues to emerge as an important cause of foodborne illness, and several foodborne disease outbreaks caused by V. parahaemolyticus have been linked to the consumption of contaminated seafood, in particular those consumed raw such as oysters. In response to these outbreaks, especially during the 1990s, several cultural, immunological‐based and molecular detection methods have been developed, which allow for rapid detection and quantification of total and pathogenic V. parahaemolyticus. The development of molecular methodology has allowed for clinical and environmental isolates of V. parahaemolyticus to be subtyped, thus providing the framework for risk‐based strategies aimed at controlling foodborne outbreaks cause by this pathogen. It is important that the detection and typing methods strive to accomplish detection and differentiation of the pathogenic strains from environmental (non‐pathogenic) ones, as well as to detect the presence of the organism and not just the presence of V. parahaemolyticus produced toxins, which can also be produced by closely related species. This review covers the current status of detection and typing methodology for identification and characterisation of V. parahaemolyticus from seafood.     

Occurrence of the tdh and trh genes in Vibrio parahaemolyticus isolates from waters and raw shellfish collected in two French coastal areas and from seafood imported into France

The occurrence of the hemolysin genes, tdh and trh, in Vibrio parahaemolyticus strains isolated from environmental samples collected in two French coastal areas, clinical samples, and seafood products imported into France was studied. Polymerase chain reaction (PCR) with two sets of primers was used to detect the hemolysin genes. Most of the clinical isolates (91%) and 1.5% of the isolates from seafood possessed the hemolysin genes. Three and fifteen percent, respectively, of the two groups of environmental strains carried the hemolysin genes depending on the geographic site. The tdh and trh genes play important roles in virulence. Thus, our results indicate that pathogenic V. parahaemolyticus isolates are present in French coastal areas and in seafood imported into France. Furthermore, they may also be present in French seafood products.     

Dissemination of Enterococcus faecalis and Enterococcus faecium in a Ricotta Processing Plant and Evaluation of Pathogenic and Antibiotic Resistance Profiles

In this work, the sources of contamination by Enterococcus spp. in a ricotta processing line were evaluated. The isolated strains were tested for virulence genes (gelE, cylA,B, M, esp, agg, ace, efaA, vanB), expression of virulence factors (hemolysin and gelatinase), and the resistance to 10 different antibiotics. Enterococcus faecium and Enterococcus faecalis were subjected to discriminatory identification by intergenic spacer region (ITS)‐polymerase chain reaction and sequencing of the ITS region. The results showed that Enterococcus spp. was detected in the raw materials, environment samples and the final product. None of the 107 Enterococcus isolates were completely free from all virulence genes considered. A fraction of 21.5% of the isolates containing all of the genes of the cylA, B, M operon also expressed β‐hemolysis. Most of the isolates showed the gelE gene, but only 9.3% were able to hydrolyze gelatin. In addition, 23.5% of the observed Enterococcus isolates had the vanB gene but were susceptible to vancomycin in vitro. The dissemination of antibiotic‐resistant enterococci was revealed in this study: 19.3% of the E. faecium samples and 78.0% of the E. faecalis samples were resistant to at least one of the antibiotics tested. Sequencing of region discriminated 5 and 7 distinct groups among E. faecalis and E. faecium, respectively. Although some similarity was observed among some of the isolates, all E. faecalis and E. faecium isolates had genetic differences both in the ITS region and in the virulence profile, which makes them different from each other.     

Prevalence and characterization of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus isolated from retail yak butter in Tibet,China

This study aimed to investigate the prevalence, molecular characteristics and antibiotic resistance of Staphylococcus aureus isolates from yak butter in Tibet, China. A total of 218 yak butter samples were collected from retail stores in Tibet and screened for Staph. aureus. Furthermore, the virulence genes, resistance genes, antimicrobial susceptibility, and molecular typing [pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and staphylococcal protein A (spa) typing] of Staph. aureus isolates were detected. The results showed that 12.4% of yak butter samples were contaminated with Staph. aureus, including 5 samples positive for methicillin-resistant Staph. aureus (MRSA). Among all isolates, 96.3% harbored one or more virulence genes, including classical (sea and sec), novel enterotoxin-encoding genes (seh, sek, sel, and seq), and hemolysin genes (hla and hld). All isolates were resistant to at least 2 different antibiotic classes, and the isolates were most commonly resistant to sulfonamides, β-lactams, and erythromycin. For resistance genes, blaZ (74.1%) was most frequently detected, followed by dfrG (51.9%), erm(B) (22.2%), mecA (18.5%), tet(K) (14.8%), aph(2″)-Ia, aph(3′)-III, and ant(6)-Ia (11.1% for each), and erm(C) (7.4%). We detected 8 spa types, 6 sequence types (ST), and 5 clonal complex (CC) types. In addition, 1 isolate of Staph. aureus was nontypeable. We found that CC1-ST1-t559 (55.6%) was the most predominant clone, followed by CC59-ST59-t437 (11.1%), CC5-ST5-t002 (7.4%), CC1-ST1, CC1-ST1-t114, CC1-ST573-t4938, CC1-ST573-t8915, CC30-ST30-t021, and CC25-ST25-t167 (3.7% for each). For PFGE typing, a total of 5 clusters and 15 pulsotypes were generated, and some isolates from different samples showed indistinguishable pulsotypes. Our findings suggest that yak butter produced in Tibet, China, could be contaminated by Staph. aureus strains, including MRSA strains, carrying various virulence and resistance genes, representing multiple antimicrobial resistance phenotypes. The presence of potentially virulent and antibiotic-resistant Staph. aureus strains in yak butter poses a potential threat to consumers, and appropriate measures need to be taken in the production chain to reduce the occurrence of Staph. aureus in yak butter.     

Real-time PCR von virulenten Vibrio parahaemolyticus in Fisch- und Krebstierprodukten

Pathogenic V. parahaemolyticus strains cause gastroenteritis. Contaminated fi sh products and seafood represent the most important sources of infection. V. parahaemolyticus strains from patients differ from environmental isolates by their production of the haemolysins TDH and TRH that represent their main virulence factors. 710 specimens of fish and crayfish products were examined by an evaluated PCR-/real-time PCR. This detection method of virulent V. parahaemolyticus isolates reduces the working time by one day after a selective enrichment of vibrios with alkaline saline peptone water.

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Zusammenfassung: Pathogene Vibrio parahaemolyticus rufen Gastroenteritis hervor. Die Hauptinfektionsquellen stellen kontaminierte Fischprodukte und Meeresfrüchte dar. V. parahaemolyticus- Patientenisolate unterscheiden sich von Umweltisolaten durch die Anwesenheit der H?molysine TDH und TRH als deren wichtigste Virulenzfaktoren. Evaluierte PCR-/real-time PCR-Verfahren wurden zur Untersuchung von 710 Proben Fisch- und Krebstierprodukte eingesetzt. Nach der Selektivanreicherung von Vibrionen in alkalischem, salinischem Peptonwasser führen die real-time PCR-Verfahren der Gene von TDH und TRH zu einer Ersparnis von mindestens einem Arbeitstag beim Nachweis virulenter V. parahaemolyticus-Isolate.

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Eingegangen: 18. Januar 2007     

SIDEROPHORE PRODUCTION, SERUM RESISTANCE, HEMOLYTIC ACTIVITY AND EXTENDED-SPECTRUM β-LACTAMASE-PRODUCING KLEBSIELLA SPECIES ISOLATED FROM MILK AND MILK PRODUCTS

This study aimed at the isolation and identification of Klebsiella spp. from dairy product to establish their public health significance by determining their virulence factors, antibiotic resistance and extended‐spectrum β‐lactamase (ESBL). Klebsiella pneumoniae, Klebsiella oxytoca and Klebsiella rhinoscleromatis were identified in 25 (58%), 11 (26%) and 7 (16%) isolates, respectively. A high prevalence of Klebsiella isolates had virulence factors such as siderophore production (63%), serum resistance (32.5%) and hemolytic activity (58%). ESBL‐producing Klebsiella spp. was detected in 35% of the isolates. Resistance to the antimicrobial agents tested was found to be much higher in the ESBL‐producing Klebsiella spp. than in non‐ESBL‐producing isolates. All ESBL‐producing Klebsiella spp. showed high‐level resistance to cephalosporins and monobactams. The majority of the serum resistant, siderophore, hemolysin and ESBL producers were K. pneumoniae.