Sequencing and Partial Molecular Characterization of BAB-TMP, the Babeș Strain of the Fixed Rabies Virus Adapted for Multiplication in Cell Lines

The rabies virus is a major zoonosis that causes severe nervous disease in humans, leading to paralysis and death. The world's second anti-rabies center was established in 1888 by Victor Babeș, in Bucharest, where an eponymous strain of rabies was isolated and used to develop a method for immunization. The Babeș strain of the rabies virus was used for over 100 years in Romania to produce a rabies vaccine for human use, based on animal nerve tissue, thus having a proven history of prophylactic use. The present study aimed to sequence the whole genome of the Babeș strain and to explore its genetic relationships with other vaccine strains as well as to characterize its relevant molecular traits. After being adapted for multiplication in cell lines and designated BAB-TMP, 99% of the viral genome was sequenced. The overall organization of the genome is similar to that of other rabies vaccine strains. Phylogenetic analysis indicated that the BAB-TMP strain is closely related to the Russian RV-97 vaccine strain, and both seem to have a common ancestor. The nucleoprotein gene of the investigated genome was the most conserved, and the glycoprotein showed several unique amino acid substitutions within the major antigenic sites and linear epitopes.

Genome characterisation of norovirus GII.P17-GII.17 detected during a large gastroenteritis outbreak in Romania in 2021

Norovirus (NoV) is one of the leading causes of acute gastroenteritis worldwide. Genotype GII.P17-G.II.17 emerged in Asia between 2013 and 2015 and transiently replaced the GII.4 Sydney 2012 variant circulating at that time. We present the genome characterisation of a GII.P17-GII.17 strain causing a large outbreak in Romania in 2021. Our study shows that the 2021 strain belongs to a novel cluster of genotype GII.17, different from the two previously recognised P.17 clusters. Distinctive substitutions in predicted conformational epitopes of VP1 were identified for this new cluster. Also, our phylogenetic analysis showed the existence of another P.17 cluster grouping strains from France and Canada.

First Detection and Molecular Characterization of Usutu Virus in Culex pipiens Mosquitoes Collected in Romania

Usutu virus (USUV) is an emergent arbovirus in Europe causing mortality in bird populations. Similar to West Nile virus (WNV), USUV is maintained in sylvatic cycles between mosquito vectors and bird reservoirs. Spillover events may result in human neurological infection cases. Apart from indirect evidence provided by a recent serological study in wild birds, the circulation of USUV in Romania was not assessed. We aimed to detect and molecular characterize USUV circulating in mosquito vectors collected in South-Eastern Romania-a well-known WNV endemic region-during four transmission seasons. Mosquitoes were collected from Bucharest metropolitan area and Danube Delta, pooled, and screened by real-time RT-PCR for USUV. Partial genomic sequences were obtained and used for phylogeny. USUV was detected in Culex pipiens s.l. female mosquitoes collected in Bucharest, in 2019. The virus belonged to Europe 2 lineage, sub-lineage EU2-A. Phylogenetic analysis revealed high similarity with isolates infecting mosquito vectors, birds, and humans in Europe starting with 2009, all sharing common origin in Northern Italy. To our knowledge, this is the first study characterizing a strain of USUV circulating in Romania.

Distribution of Insecticide Resistance Genetic Markers in the West Nile Virus Vector Culex pipiens from South-Eastern Romania

Culex pipiens pipiens and Culex pipiens molestus mosquitoes are the vectors of West Nile virus in south-eastern Romania, an area of intense circulation and human transmission of this virus. The level of insecticide resistance for the mosquito populations in the region has not been previously assessed. Culex pipiens mosquitoes collected between 2018 and 2019 in south-eastern Romania from different habitats were subjected to biotype identification by real-time PCR. Substitutions causing resistance to organophosphates and carbamates (F290V and G119S in acetylcholinesterase 1) and to pyrethroids (L1014F in voltage gated Na⁺ channel) were screened by PCR or sequencing. Substitutions F290V and G119S were detected at very low frequencies and only in heterozygous state in Culex pipiens molestus biotype specimens collected in urban areas. The molestus biotype population analysed was entirely homozygous for L1014F, and high frequencies of this substitution were also found for pipiens biotype and hybrid mosquitoes collected in urban and in intensive agriculture areas. Reducing the selective pressure by limiting the use of pyrethroid insecticides only for regions where it is absolutely necessary and monitoring L1014F mutation should be taken into consideration when implementing vector control strategies.

A Snapshot of the Genetic Diversity of Salmonella Enteritidis Population Involved in Human Infections in Romania Taken in the European Epidemiological Context

In the absence of consistent national molecular typing data to enhance the surveillance of Salmonella Enteritidis, it was considered useful to collect baseline information on the genetic diversity and antibiotic susceptibility of strains isolated in Romania between January 2016 and April 2020 and compare them to strains described in major international outbreaks of the same period. A collection of 245 clinical isolates were genotyped by a standardised multiple-locus variable-number of tandem repeats analysis (MLVA) 5-loci protocol and screened for antimicrobial resistance against 15 compounds. Twenty strains were further subjected to whole genome sequencing (WGS) and compared to epidemiologically relevant high-throughput sequencing data available in European databases. Twenty-seven MLVA genotypes were identified, of which three, commonly reported in Europe between 2016–2020, covered 72% of the collection. Antibiotic resistance was detected in 30% of the strains, with resistance to nalidixic acid and ciprofloxacin as the most common phenotype, and also associated with two prevalent MLVA clones. WGS-derived multilocus sequence typing (MLST) revealed a single sequence type (ST11) further resolved into 10 core-genome MLST complex types. The minimum spanning tree constructed from the cgMLST data clustered Romanian and international strains, which shared more than 95% of the core genes, revealing links with a contemporaneous multi-country outbreak. This study could be regarded as a forerunner to the advent of using this integrative approach in the public health practice at a national level and thus contribute to the concerted actions at a European level to stop outbreaks.

Characterization and Host-Feeding Patterns of Culex pipiens s.l. Taxa in a West Nile Virus-Endemic Area in Southeastern Romania

Culex pipiens sensu lato has been documented as West Nile virus (WNV) vector in southeastern Romania. Bucharest, the densely populated capital city of Romania, and the surrounding Ilfov county are WNV hotspots. In this area, the morphologically indistinguishable biotypes of Cx. pipiens, namely pipiens and molestus, are usually differentiated by their behavioral and physiological traits. Their involvement in WNV transmission, as suggested by entomological investigations, was not previously documented for each biotype. We used a Real-Time PCR assay based on CQ11 microsatellite to identify the Cx. pipiens biotypes and their hybrids collected in various habitats in the Bucharest metropolitan area. A sympatric distribution of both biotypes was observed, with a preference of green areas for pipiens, and human settings and animal farmlands for molestus. In the latter habitats, pipiens and molestus were found in mixed aboveground populations. A low number of hybrids was found suggesting existence of reproductive isolation. In subway tunnels molestus was dominant with a higher number of hybrids recorded than aboveground. Blood-engorged mosquitoes were identified to biotype and the blood meal source identified by DNA barcoding. Overall, Cx. pipiens s.l. fed mainly on birds, commonly on house sparrows, collared doves, and blackbirds, which are potential WNV-amplifying hosts. The preference for avian hosts was expressed strongest by pipiens biotype, while molestus was substantially less specific, feeding on avian and mammal hosts with similar frequency, with humans representing 20% of the hosts. Hybrids had a host choice closer to that of molestus. These findings highlight the role of pipiens biotype as enzootic/epizootic vector, and specifically show molestus as the bridge vector for WNV. The pipiens and molestus biotypes show important differences in habitat preferences, including oviposition; these findings demonstrate that targeted mosquito control to limit WNV transmission may be possible.

Emergence of Toscana Virus, Romania, 2017-2018

We describe a series of severe neuroinvasive infections caused by Toscana virus, identified by real-time reverse transcription PCR testing, in 8 hospitalized patients in Bucharest, Romania, during the summer seasons of 2017 and 2018. Of 8 patients, 5 died. Sequencing showed that the circulating virus belonged to lineage A.

Application of the susceptible-infected-recovered deterministic model in a GII.P17 emergent norovirus strain outbreak in Romania in 2015

Purpose

This study shows the epidemiological profile of the first gastroenteritis outbreak of GII.P17 in the Romanian territory. An outbreak with such large amplitude in a European territory was previously undocumented.

Patients and methods

Using a cross-sectional design, with the susceptible-infected-recovered (SIR) deterministic compartmental model for a fixed population, and the cluster method for establishing the high-incidence zones, we carried out our investigation by means of questionnaires containing personal data, affected collectivities, disease onset and duration, symptoms displayed, medical assistance provided, previous antibiotic intake where applicable, food consumption and water sources, and sanitation conditions. The confirmation of cases was done based on the typical norovirus gastroenteritis symptomatology and using three laboratory confirmations (by molecular diagnosis) for GII.P17-GII.17 genotype noroviruses from three patients.

Results

A gastroenteritis outbreak occurred in October-November 2015, affecting 328 people in Arad, a county in Western Romania, covering 44 neighbouring localities with a total population of 35,440 people. The study detected an inter-human transmission of the infection, with an intrafamilial risk of disease of 2.26 (95% CI 1.76 to 2.90) compared with the community transmission (in school collectivity). The basic reproduction number Ro dropped from 1.26 to 0.18 during weeks 43:44, after controlling the transmission by decontamination and isolation.

Conclusion

SIR made it possible to highlight the expansion of the emerging norovirus strain infection from community to family collectivities. This study provides practical solutions to limit disease cases, even in the absence of etiology, and shows the importance of sometimes underestimated traditional control methods.

West Nile virus lineage 2 in Romania, 2015-2016: co-circulation and strain replacement

Background

West Nile virus (WNV) is endemic in southeastern Romania and, after the unprecedented urban epidemic in Bucharest in 1996 caused by lineage 1 WNV, cases of West Nile fever have been recorded every year. Furthermore, a new outbreak occurred in 2010, this time produced by a lineage 2 WNV belonging to the Eastern European clade (Volgograd 2007-like strain), which was detected in humans and mosquitoes in the following years.

Results

We report here, for the first time, the emergence, in 2015, of lineage 2 WNV belonging to the monophyletic Central/Southern European group of strains which replaced in 2016, the previously endemized lineage 2 WNV Volgograd 2007-like strain in mosquito populations. The emerged WNV strain harbors H249P (NS3 protein) and I159T (E glycoprotein) substitutions, which have been previously associated in other studies with neurovirulence and efficient vector transmission.

Conclusions

In 2016, both early amplification of the emerged WNV and complete replacement in mosquito populations of the previously endemized WNV occurred in southeastern Romania. These events were associated with a significant outbreak of severe West Nile neuroinvasive disease in humans.

Molecular Typing of Escherichia coli O157 Isolates from Romanian Human Cases

Verocytotoxin-producing Escherichia coli (VTEC) of serogroup O157 are among the most important causes of severe cases of foodborne disease and outbreaks worldwide. As little is known about the characteristic of these strains in Romania, we aimed to provide reference information on the virulence gene content, phylogenetic background, and genetic diversity of 7 autochthonous O157 strains collected during 2016 and 2017 from epidemiologically non-related cases. These strains were typed by a combination of phenotypic and molecular methods routinely used by the national reference laboratory. Additionally, 4 of them were subjected to whole-genome sequencing (WGS), and public web-based tools were used to extract information on virulence gene profiles, multilocus sequence types (MLST), and single nucleotide polymorphism (SNP)-based phylogenetic relatedness. Molecular typing provided evidence of the circulation of a polyclonal population while distinguishing a cluster of non-sorbitol-fermenting, glucuronidase-negative, phylogenetic group E, MLST 1804 strains, representing lineage II and clade 7, which harbored vtx2c, eae-gamma, and ehxA genes. A good correlation between the routine typing methods and WGS data was observed. However, SNP-based genotyping provided a higher resolution in depicting the relationships between the O157:H7 strains than that provided by Pulse-field gel electrophoresis. This study should be a catalyst for improved laboratory-based surveillance of autochthonous VTEC.

Molecular characterisation of human Shiga toxin-producing Escherichia coli O26 strains: results of an outbreak investigation, Romania, February to August 2016

At the beginning of 2016, an increase in paediatric haemolytic uremic syndrome (HUS) cases was observed in Romania. The microbiological investigations allowed isolation of Shiga toxin-producing Escherichia coli (STEC) O26 as the causative agent from most cases. Methods: An enhanced national surveillance of HUS and severe diarrhoea was established across the country following the identification of the first cases and was carried out until August 2016. A total of 15 strains were isolated from 10 HUS and five diarrhoea cases. Strains were characterised by virulence markers (i.e. stx type/subtype, eae, ehxA genes), phylogroup, genetic relatedness and clonality using PCR-based assays, PFGE and multilocus sequence typing (MLST). The first six strains were further characterised by whole genome sequencing (WGS). Results: Five PCR-defined genotypes were distinguished. All strains from HUS cases harboured stx2a and eae, with or without stx1a, while strains from diarrhoea cases carried exclusively stx1a and eae genes. PFGE resolved strains into multiple pulsotypes, compatible with a certain geographic segregation of the cases, and strains were assigned to phylogroup B1 and sequence type (ST) 21. WGS confirmed the results of conventional molecular methods, brought evidence of O26:H11 serotype, and complemented the virulence profiles. Discussion/conclusion: This first description of STEC O26 strains from cases in Romania showed that the isolates belonged to a diverse population. The virulence content of most strains highlighted a high risk for severe outcome in infected patients. Improving the national surveillance strategy for STEC infections in Romania needs to be further considered.

Transmission Dynamics of the West Nile Virus in Mosquito Vector Populations under the Influence of Weather Factors in the Danube Delta, Romania

Mosquitoes were collected in the Danube Delta during the active seasons of 2011-2013. For Culex spp. mosquitoes, the abundance was calculated. Culex pipiens (sensu lato), (s.l.) and Culex modestus pools were tested for the presence of West Nile virus (WNV) genome, and the maximum likelihood of the infection rate was established. Mean daily temperatures and precipitation were obtained for the closest meteorological station. A negative binominal model was used to evaluate linkages between the temperature/precipitation and mosquito population size. A zero-inflated negative binomial model was used to test the relationship between the temperature and the infection rate. A single complex model for infection rate prediction was also used. The linkages were calculated for lag 0 and for 10 days earlier (lag 1), 20 days earlier (lag 2), and 30 days earlier (lag 3). Significant positive linkages (P < 0.001) were detected between temperature and mosquito population size for lag 1, lag 2, and lag 3. The linkages between temperature and infection rates were positive and significant for lag 2 and lag 3. Negative significant (P < 0.001) results were detected between precipitation and infection rates for lags 1, 2, and 3. The complex model showed that the best predictors for infection rate are the temperature, 20 days earlier (positive linkage) and the precipitation, 30 days earlier (negative linkage). Positive temperature anomalies in spring and summer and rainfall decrease contributed to the increase in the Culex spp. abundance and accelerated the WNV amplification in mosquito vector populations in the following weeks.

Impact of hepatitis C virus core mutations on the response to interferon-based treatment in chronic hepatitis C

AIM

To determine whether hepatitis C virus (HCV) core substitutions play a role in the response to interferon-based treatment in Caucasian patients.

METHODS

One hundred eight HCV chronically infected patients initiating treatment with pegylated IFN plus ribavirin for 48 wk were tested for baseline substitutions at codons 70 and 91 of the viral core protein (BigDye Terminator vers.3.1, Applied Biosystems,) and for genetic polymorphisms in host IL28B gene rs12979860 (Custom TaqMan 5' allelic discrimination assay; Applied Biosystems).

RESULTS

Of the patients, all were infected with HCV genotype 1b, 44.4% had low baseline HCV viral load, and 37.9% had mild/moderate fibrosis. Only 38.9% achieved therapeutic success, defined as sustained virological response (SVR). Eighty-eight percent of the patients presented at least one substitution at core position 70 (R70Q/H) or/and position 91 (L91M). The favorable IL28B CC polymorphism was detected in only 17.6% of the patients. In the univariate analysis, young age (P < 0.001), urban residence (P = 0.004), IL28B CC genotype (P < 0.001), absence of core mutations (P = 0.005), achievement of rapid virologic response (P < 0.001) and early virological response (P < 0.001) were significantly correlated with SVR. A multivariate analysis revealed three independent predictors of therapeutic success: young age (P < 0.001), absence of core substitutions (P = 0.04) and IL28B CC genotype (P < 0.001); the model correctly classified 75.9% of SVR cases with a positive predictive value of 80.7%.

CONCLUSION

HCV core mutations can help distinguish between patients who can still benefit from the affordable IFN-based therapy from those who must be treated with DAAs to prevent the evolution towards end-stage liver disease.

Molecular identification of emergent GII.P17-GII.17 norovirus genotype, Romania, 2015

The novel GII.P17-GII.17 norovirus genotype has been reported as cause of gastroenteritis outbreaks in China and Japan since the winter season 2014/15, replacing the pandemic strain GII.4 Sydney 2012. These emergent strains have also been sporadically reported on other continents than Asia. GII.P17-GII.17 isolates, similar to Kawasaki308 2015, were identified in three patients during a large outbreak of acute gastroenteritis affecting 328 people in Romania, in neighbouring localities, in 2015.

Retrospective study reveals the circulation of norovirus genotype GII.P21-GII.2 in Romania

Noroviruses are the leading cause of acute gastroenteritis, causing significant economic burden globally. Infection is self-limiting, occurring as sporadic cases or producing outbreaks associated with consumption of contaminated water or food. All age groups are affected and person to person transmission is frequent. Except a recent outbreak in Romania caused by the emergent genotype GII.P17-GII.17, few data regarding the circulation of noroviruses in our country are available. We retrospectively analyzed stool samples from acute gastroenteritis patients hospitalized in Romania between 2005 and 2008. Noroviruses were detected by RT-PCR and phylogenetic analysis was inferred from partial sequences spanning ORF1 and ORF2. Recombinant GII.P21-GII.2 isolates were found in two adult patients from a cluster of acute gastroenteritis in 2006. Molecular analysis based on partial genomic sequences indicated high degree of similarity between the two isolates and grouped them with cosmopolitan strains circulating in the same period of time. Along with the high rate of mutation, recombination is an important driving force in norovirus evolution. GII.P21 isolates, formerly known as GII.b recombinants, have been detected in Europe since 2000 and associated with sporadic cases and outbreaks of gastroenteritis worldwide. This is the first work describing norovirus GII.P21-GII.2 identified in Romania.

Established Population of the Invasive Mosquito Species Aedes albopictus in Romania, 2012-14

During an entomological investigation carried out in Bucharest and surroundings in fall of 2012, 45 adult mosquitoes (38 females and 7 males) of Aedes albopictus were collected in a neighborhood from the southern area of the city. The morphological identification of the species was further confirmed by sequencing 2 mitochondrial DNA markers: the cytochrome c oxidase subunit I and NADH dehydrogenase subunit 5 genes. Aedes albopictus was collected again in 2013 in the same area from July until October. During late summer the species was found also in another location in the city, downtown Bucharest. Larvae were found in water barrels and other types of household containers, as well as in rain catch basins. In 2014, following a nuisance complaint of a Bucharest inhabitant, the entomological investigation found aggressive Ae. albopictus adults on his property that harbored many mosquito larvae in container-type breeding habitats. These findings are the 1st records of this invasive species and of its breeding population in Romania, and show maintenance of the species over 2 winter seasons. Surveillance of the species outside the area of the capital city was not performed, therefore it is not known whether Ae. albopictus has been introduced in other regions of the country. The presence of Ae. albopictus has been reported every year (2012-14) to competent public health authorities, stressing on the importance of surveillance and of implementation of control measures.

West Nile virus circulation in South-Eastern Romania, 2011 to 2013

Lineage 2 West Nile virus (WNV), previously found only in sub-Saharan Africa and Madagascar, was identified in Hungary in 2004 and has rapidly expanded in Europe in the past decade. Following a significant outbreak of West Nile fever with neurological cases caused by lineage 1 WNV in Romania in 1996, scattered cases have been recorded in the south-east of the country in each transmission season. Another outbreak, affecting a larger area and caused by lineage 2 WNV, was recorded in 2010. We analysed human sera from neuroinvasive West Nile fever cases and mosquitoes, sampled in south-eastern Romania between 2011 and 2013, for the presence of WNV genome, and obtained partial NS5 and envelope glycoprotein sequences. Human- and mosquito-derived WNV sequences were highly similar (99%) to Volgograd 2007 lineage 2 WNV and differed from isolates previously detected in central and southern Europe. WNV was detected in one pool of Culex pipiens s.l. males, documenting vertical transmission. Lineage 4 WNV, of unknown pathogenicity to mammals, was found in the amphibian-feeding mosquito Uranotaenia unguiculata from the Danube Delta. Our results present molecular evidence for the maintenance of the same isolates of Volgograd 2007-like lineage 2 WNV in south-eastern Romania between 2011 and 2013.

GENOMIC ANALYSIS OF HEPATITIS B VIRUS STRAINS INFECTING ROMANIAN PATIENTS

Chronic hepatitis B is widespread and represents an important cause of morbidity and mortality due to the evolution to cirrhosis and hepatocellular carcinoma. This study was designed to improve the national laboratory surveillance of hepatitis B virus (HBV) infection, focusing on genomic analysis of isolates from Romanian patients. Sera from ten patients with HBV were collected and analyzed. Phylogenetic analysis was conducted on a DNA fragment spanning almost the entire genome. The occurrence of mutations was assessed for each open reading frame in the viral genome. Phylogenetic analysis revealed five isolates belonging to genotype A (subgenotype A2) and other five clustering with genotype D strains (subgenotype D1). Two patients treated with lamivudine were found to carry isolates harboring rtM204V lamivudine resistance mutation. An HBV isolate displaying a lamivudine complex resistance pattern, rtM204I in conjunction with rtL180M and rtA200V, was found in a lamivudine naïve patient. All samples harbored sA105P substitution, usually found in HBIg therapy escape isolates. Three of the studied strains were simultaneously displaying T1753, T1762 and A1764 mutations which in vitro induce enhanced genome replication and reduction of HBeAg expression. The sequence obtained from a patient with decompensated liver cirrhosis presents a novel type of insertion consisting of nine nucleotides between positions 260 and 261 in the X gene. Despite the small number of samples, our findings suggest the need to determine the drug resistance pattern for each patient before taking a therapeutic decision and also highlight the necessity of knowing the real level of drug resistance among HBV strains circulating in Romania.

SCREENING OF PROTEASE INHIBITORS RESISTANCE MUTATIONS IN HEPATITIS C VIRUS ISOLATES INFECTING ROMANIAN PATIENTS UNEXPOSED TO TRIPLE THERAPY

Although the European recommendations include the use of new antiviral drugs for the treatment of hepatitis C, in Romania the current treatment remains interferon plus ribavirin. First generation viral protease inhibitors (i.e. boceprevir, telaprevir), which have raised the chances of obtaining viral clearance in up to 70% of infection cases produced by genotype 1 isolates, have not been introduced yet as standard treatment in our country. The success of these new antivirals is limited by the occurrence and selection of resistance mutations during therapy. We set-up a molecular study aiming to detect any resistance mutations to boceprevir and telaprevir harbored by hepatitis C isolates infecting Romanian patients naïve to viral protease inhibitors. Since these new antivirals are efficient and approved for genotype 1 infection, viral samples were genotyped following a protocol previously developed by our research group. We analyzed by both population sequencing and molecular cloning and sequencing the NS3 protease region of hepatitis C virus isolates infecting patients which were not previously exposed to boceprevir and telaprevir. All the analyzed samples were subtype 1b and resembled the samples collected in recent years from Romanian patients. Molecular cloning followed by sequencing showed great intra-host diversity, which is known to represent the source of isolates with different resistance phenotypes. Both population sequencing and molecular cloning followed by clone sequencing revealed two boceprevir resistance mutations (T54S and V55A), respectively, a telaprevir resistance mutation (T54S) in the sequences obtained from a patient with chronic hepatitis C. To our knowledge, this is the first study indicating the existence of pre-treatment resistance mutations to boceprevir and telaprevir in hepatitis C virus isolates infecting Romanian patients.

Molecular epidemiology of dengue fever cases imported into Romania between 2008 and 2013

BACKGROUND

Dengue fever is the commonest arthropod-borne infection worldwide. In recent years, rapid growth in global air travel has resulted in a considerable increase in the incidence of imported cases. In Romania it is now the second most frequent cause for hospitalization (after malaria) in patients arriving from tropical regions.

METHODS

Serological and molecular diagnostics were applied to samples obtained between 2008 and 2013 from travelers with suspected dengue. Molecular typing was performed by RT-PCR followed by sequencing of the E-NS1 junction.

RESULTS

Twelve of 37 suspected cases were confirmed and three remained probable. The infections were acquired in endemic regions in Asia, Africa and in Europe (Madeira Island). Dengue virus nucleic acid was detected and sequenced in nine cases. Phylogenetic analysis indicated that the viruses were of genotypes I and V of serotype 1, cosmopolitan genotype of serotype 2 and genotypes I and III of serotype 3.

CONCLUSIONS

Romanian tourists traveling to dengue-endemic countries are at risk of acquiring dengue infection. Appropriate prevention measures prior to travel and upon return should be taken, particularly as the dengue secondary vector Aedes albopictus is now established in Bucharest.

Dobrava virus carried by the yellow-necked field mouse Apodemus flavicollis, causing hemorrhagic fever with renal syndrome in Romania

Hemorrhagic fever with renal syndrome (HFRS) has been confirmed by serological methods during recent years in Romania. In the present study, focus-reduction neutralization tests (FRNT) confirmed Dobrava hantavirus (DOBV) as the causative agent in some HFRS cases, but could not distinguish between DOBV and Saaremaa virus (SAAV) infections in other cases. DOBV was detected by a DOBV-specific TaqMan assay in sera of nine patients out of 22 tested. Partial sequences of the M genomic segment of DOBV were obtained from sera of three patients and revealed the circulation of two DOBV lineages in Romania. Investigation of rodents trapped in Romania found three DOBV-positive Apodemus flavicollis out of 83 rodents tested. Two different DOBV lineages were also detected in A. flavicollis as determined from partial sequences of the M and S genomic segments. Sequences of DOBV in A. flavicollis were either identical or closely related to the sequences obtained from the HFRS patients. The DOBV strains circulating in Romania clustered in two monophyletic groups, together with strains from Slovenia and the north of Greece. This is the first evidence for the circulation of DOBV in wild rodents and for a DOBV etiology of HFRS in Romania.

Whooping cough in South-East Romania: a 1-year study

The incidence of whooping cough in Romania is substantially underestimated, and, as noted by the health authorities, this is mostly due to the lack of both awareness and biological diagnosis. We conducted a 1-year study in Bucharest in order to assess the circulation of Bordetella pertussis, the main etiological agent of whooping cough. Fifty-one subjects suspected of whooping cough were enrolled. Culture, real-time PCR, and enzyme-linked immunosorbent assay were used for laboratory diagnosis. Whooping cough patients (63%) were distributed among all age groups, and most were unvaccinated, incompletely vaccinated, or had been vaccinated more than 5 years previously. Bordetella holmesii DNA was detected in 22% of the bordetellosis cases; these patients included adults; teenagers; and, surprisingly, young children. B. pertussis isolates were similar to the clinical isolates currently circulating elsewhere in Europe. One isolate does not express pertactin, an antigen included in some acellular pertussis vaccines.

Microbiological changes and diversity in autochthonous non-toxigenic Corynebacterium diphtheriae isolated in France

Autochtonous toxigenic Corynebacterium diphtheriae have disappeared in mainland France, but non-toxigenic C. diphtheriae are still circulating. Using phenotypic and molecular tools, we retrospectively characterized 103 non-toxigenic C. diphtheriae collected in mainland France and highlight several changes. The proportion of C. diphtheriae belfanti increased between 1977 and 2011 and it is the most frequent biotype recovered in recent years. Resistance to ciprofloxacin has increased and most isolates with decreased sensitivity belong to the belfanti biotype. Using multilocus sequence typing, we demonstrate that French isolates are distributed in a large number of sequence types and identify three distinct lineages. C. diphtheriae mitis and gravis form lineage I while C. diphtheriae belfanti forms lineages II and III. Almost all isolates of lineage II are part of a unique clonal complex or are very close to it. Most French isolates have a dtxR sequence homologous to that of toxigenic isolates, suggesting that if lyzogenised by a corynephage, they can express diphtheria toxin.

Q fever endocarditis in Romania: the first cases confirmed by direct sequencing

Infective endocarditis (IE) is a serious, life-threatening disease with highly variable clinical signs, making its diagnostic a real challenge. A diagnosis is readily made if blood cultures are positive, but in 2.5 to 31% of all infective endocarditis cases, routine blood cultures are negative. In such situations, alternative diagnostic approaches are necessary. Coxiella burnetii and Bartonella spp. are the etiological agents of blood culture-negative endocarditis (BCNE) most frequently identified by serology. The purpose of this study is to investigate the usefulness of molecular assays, as complementary methods to the conventional serologic methods for the rapid confirmatory diagnostic of Q fever endocarditis in patients with BCNE. Currently, detection of C. burnetii by culture or an antiphase I IgG antibody titers >800 represents a major Duke criterion for defining IE, while a titers of >800 for IgG antibodies to either B. henselae or B. quintana is used for the diagnosis of endocarditis due to Bartonella spp. We used indirect immunofluorescence assays for the detection of IgG titers for C. burnetii, B. henselae and B. quintana in 57 serum samples from patients with clinical suspicion of IE. Thirty three samples originated from BCNE patients, whereas 24 were tested before obtaining the blood cultures results, which finally were positive. The results of serologic testing showed that nine out of 33 BCNE cases exhibited antiphase I C. burnetii IgG antibody titer >800, whereas none has IgG for B. henselae or B. quintana. Subsequently, we used nested-PCR assay for the amplification of C. burnetii DNA in the nine positive serum samples, and we obtained positive PCR results for all analyzed cases. Afterwards we used the DNA sequencing of amplicons for the repetitive element associated to htpAB gene to confirm the results of nested-PCR. The results of sequencing allowed us to confirm that C. burnetii is the causative microorganism responsible for BCNE. In conclusion, the nested PCR amplification followed by direct sequencing is a reliable and accurate method when applied to serum samples, and it may be used as an additional test to the serological methods for the confirmatory diagnosis of BCNE cases determined by C. burnetii.

Molecular epidemiology of hepatitis C virus strains from Romania

BACKGROUND AND AIMS

A high seroprevalence of Hepatitis C Virus (HCV) infection has been reported in Romania, with limited data on the viral subtypes' distribution. In order to detect any changes in the genetic composition of the epidemic, a survey on the recent profile of circulating HCV genotypes was conducted.

METHODS

241 hepatitis C infected patients with active viral replication diagnosed between September 2004 - October 2008 were included in a retrospective study. Genotyping using commercial Line Probe Assay (Innogenetics) was confirmed by sequencing of Core PCR products followed by phylogenetic analysis.

RESULTS

HCV subtype 1b was found in 92.6% of the samples, subtype 1a in 5.4 % of the samples, subtype 4a in 1.2%, and subtype 3a in 0.8% of the samples. Chronic hepatitis C infections with subtype 1b were found in women aged 40-60 years old with a history of blood transfusions received during surgical/obstetrical interventions. No geographical clustering was evident for HCV 1b sequences. The new emerging non-1b genotypes were detected mainly in younger patients with a history of intravenous drug use. The genetic distances among the HCV 1a strains are very homogeneous and small, with a high sequence identity with other European strains, suggesting the recent entrance of this subtype in Romania from singular or limited sources of infection.

CONCLUSION

The introduction of new HCV genotypes in Romania stimulates a continuous epidemiological surveillance, suggesting shifts in the transmission pathways and risk factors, with the possible emergence of recombinant strains in patients with multiple infections.

Screening of molecular virulence markers in Staphylococcus aureus and Pseudomonas aeruginosa strains isolated from clinical infections

Staphylococcus (S.) aureus and Pseudomonas (Ps.) aeruginosa are two of the most frequently opportunistic pathogens isolated in nosocomial infections, responsible for severe infections in immunocompromised hosts. The frequent emergence of antibiotic-resistant S. aureus and Ps. aeruginosa strains has determined the development of new strategies in order to elucidate the different mechanisms used by these bacteria at different stages of the infectious process, providing the scientists with new procedures for preventing, or at least improving, the control of S. aureus and Ps. aeruginosa infections. The purpose of this study was to characterize the molecular markers of virulence in S. aureus and Ps. aeruginosa strains isolated from different clinical specimens. We used multiplex and uniplex PCR assays to detect the genes encoding different cell-wall associated and extracellular virulence factors, in order to evaluate potential associations between the presence of putative virulence genes and the outcome of infections caused by these bacteria. Our results demonstrate that all the studied S. aureus and Ps. aeruginosa strains synthesize the majority of the investigated virulence determinants, probably responsible for different types of infections.

Quantitative real-time PCR study of the influence of probiotic culture soluble fraction on the expression of Pseudomonas aeruginosa quorum sensing genes

The opportunistic pathogen Pseudomonas (Ps.) aeruginosa causes severe infections, particularly in immunocompromised individuals and patients with cystic fibrosis (CF). A serious side effect of antibiotic therapy in Ps. aeruginosa infections is the development of resistance to antibiotics. During the infection process Ps. aeruginosa forms biofilms, rendering bacterial cells more resistant to disinfectants, antibiotics and the action of host immune defense effectors. Pseudomonas aeruginosa employs the intercellular communication system, known as quorum sensing (QS) to coordinate the expression of tissue-damaging factors. Since the QS systems controls the production of different virulence factors, it is possible that the inhibition of its regulatory activity to severely compromise the ability of Ps. aeruginosa to cause infections in humans. Many studies have shown that some probiotic strains exhibit inhibitory activity on different virulence properties of pathogenic bacteria (adherence to cellular or inert substrate, soluble virulence factors expression). The aim of the present study was to investigate by real-time RT-qPCR the influence of probiotic culture soluble factors on the QS genes expression in 30 Ps. aeruginosa strains isolated from patients hospitalized in the National Institute for Cardiovascular Infections, Prof. C.C. Iliescu Fundeni Hospital, Bucharest. The results of the real time RT-qPCR have shown that in all Ps. aeruginosa strains grown in the presence of probiotic culture sterile filtrates, the level of QS genes expression was reduced comparatively with those from control cultures. In conclusion, these results proved that the inhibition of virulence factors regulation mechanisms by soluble molecules secreted by probiotics could represent an interesting way pathogenicity and virulence attenuation in Ps. aeruginosa nosocomial strains.

A multiple typing approach is recommended for the laboratory-based surveillance of salmonellosis in Romania

In Romania, Salmonella enterica serovar Typhimurium isolates are currently typed by antimicrobial resistance profiles and phage typing, as part of the national laboratory-based surveillance system of human enteric infections. The aim of the present study was to assess the added value of complementing this approach with molecular fingerprinting, namely pulsed-field gel electrophoresis (PFGE) and multiple-locus variable-number tandem-repeats analysis (MLVA). Thirty-six S. Typhimurium isolates received by the Reference Center for Human Salmonella Infections for confirmation and typing from the Microbiology Departments of three Public Health Authorities, were selected for this study. Phage typing revealed that 14 isolates (39%) were nontypeable (NT). Twenty-two isolates were assigned to 5 phage types: DT193 (11 isolates), U302 (7 isolates), DT116 (2 isolates), DT41 (1 isolate) and DT86 (1 isolate). Antimicrobial susceptibility testing showed that all the NT and DT116 isolates were multidrug resistant and extended-spectrum betalactamase producers. All the examined isolates were typeable when using the molecular approach. Both methods gave conclusive and comparable results, documenting the genetic relatedness and discriminating the outbreak isolates from sporadic cases. We conclude that in order to improve outbreak investigation and surveillance of salmonellosis in Romania, the current routine typing of Salmonella isolates should be complemented with at least one of these DNA fingerprinting methods.

Cytokine profiles of HeLa and human diploid cells induced by different fractions of Vibrio parahaemolyticus cultures exposed to stress conditions

Vibrio (V.) parahaemolyticus is an aquatic halophilic bacteria which produces gastroenteritis and in rare cases septicaemia after the consumption of raw or under-cooked contaminated seafood.The severity of diarrheal illness caused by this bacterium is closely related to the presence of two types of hemolysins (the thermostable direct hemolysin-TDH and TDH related hemolysin-TRH) and also of type III secretion system (TTSS) proteins. The TTSS type 1 induces a wide array of effects on infected HeLa cells such as autophagy, oncosis, cell rounding and lysis. Previous studies have shown that heat shock proteins have the ability to stimulate the production of interleukins in different cellular cultures. In our studies we have stimulated two cellular lines (HeLa and human diploid cells) with different V. parahaemolyticus culture fractions in order to observe the effect on cytokines production. Thus, the purpose of this study was to analyze the expression of IL-1, IL-2, IL-4, IL-6, IL-10 and TNF-alpha induced by the cell treatment with total cellular lysate, periplasmic fractions and culture supernatants extracted from V. parahaemolyticus exposed to normal and also to stress conditions. The ELISA assay of the cytokine profile of the HeLa and HDC cell lines stimulated with different bacterial fractions revealed that in the V. parahemolyticus cultures submitted to osmotic and heat shock stress are accumulating factors (probably heat shock proteins) which are exhibiting immunomodulatory activity, responsible for the induction of a pro-inflammatory response associated with increased levels of IL-6 and TNF-alpha expression, however balanced by the stimulation of the anti-inflammatory cytokine IL-4 synthesis.

Comparative methods for genotyping hepatitis C virus isolates from Romania

Accurate genotyping of hepatitis C virus (HCV) has clinical implications for treatment orientation and epidemiological impact in tracing the contamination sources. The aim of the study was to compare a genotyping assay by restriction fragment length polymorphism (RFLP) in the HCV 5'untranslated region (5'UTR) with sequencing in the 5'untranslated and NS5B regions. One hundred and three samples, collected between 2004 and 2006 from chronically infected patients with HCV, were tested with the 5'UTR and NS5B protocols. Of the total number of the samples tested by the 5'UTR-RFLP assay (n=103) the HCV subtype could be inferred by this method for 92 samples, by 5'UTR sequencing for 16 samples out of 23 tested (n=23) and by using the NS5B sequencing for all the samples tested (n=34). Our results showed that the HCV genotype distribution in Romania is: 1b--86.4%, 1a--10.7% and 4a--2.9%. In conclusion, RFLP screening in the 5'UTR is a convenient method for HCV genotyping and discrimination between 1b and non-1b genotypes but has a poor resolving power for subtyping and evaluation of the transmission routes. Sequencing in NS5B region is more adapted than RFLP and sequencing in 5'UTR for subtyping and epidemiological investigation.

Laboratory diagnosis of infectious diarrhoea syndrome; a three years study in two hospitals of infectious diseases

Infectious diarrhoea is a syndrome caused by a variety of bacterial, viral and parasitic organisms which represents a major cause of morbidity and mortality all over the world. The wide diversity of etiological agents impairs the surveillance and the diagnosis and affects the correct treatment applied to reduce the long-term complications. Besides well known enteric pathogens such as Salmonella, Shigella and Yersinia, a high number of emergent and re-emergent aetiologies are now recognised to be at the origin of diarrhoea. The lack of a correct diagnostic algorithm and adequate methods of analyses leads to under-evaluation and incertitude in an important number of clinical cases. Our study was designed as a complex analysis of the stool specimens collected from the patients, in the purpose to improve the laboratory diagnostic and to enhance the number of confirmed cases of infectious diarrhoea. A number of 756 samples from inpatients with diarrhoea were tested targeting pathogenic and opportunistic bacteria, viruses and parasites by classical and molecular methods. We documented that, in case of non-Salmonella, non-Shigella, non-Yersinia diarrhoea, the quality of diagnostic was improved by increasing the percentage of positive specimens to 22.49% compared to 11.12% when only bacteria, 5.56% when only viruses and 4.10% when only parasites were investigated. The laboratory data are of great value in evaluating the diarrhoea syndrome offering the documentation for an accurate epidemiological response and an adequate treatment.