Influenza vaccine effectiveness in preventing hospitalizations with laboratory-confirmed influenza in Greece during the 2014-2015 season: A test-negative study.

The 2014-2015 influenza season was marked by circulation of antigenically drifted A/H3N2 strains, raising the possibility of low seasonal influenza Vaccine Effectiveness (VE). We assessed VE against hospitalization with laboratory-confirmed influenza for the 2014-2015 season, using routine surveillance data. Non-sentinel swab samples from Greek hospital inpatients were tested for influenza by RT-PCR in three laboratories, covering the entire country. We estimated VE using a test-negative design. Out of 883 patients with known vaccination status, 161 (18.2%) were vaccinated, and 392/883 patients (44.4%) tested positive for influenza, of whom 162 (41.3%) had type B and 151 (38.5%) had A/H3N2. Adjusted VE was 31.6% (95%CI: 2.9-51.8%) against any influenza, 46.8%, 95%CI: 12.5-67.6%) against type B and -1.9%, 95%CI: -69.5 to 38.7%) against A/H3N2. VE against non-ICU hospitalization appeared to be higher, but the difference did not reach statistical significance. Circulating A/H3N2 viruses showed substantial antigenic drift, while about half of the type B strains were similar to the vaccine strain. Despite the antigenic drift of the A/H3N2 strains, the vaccine still offered substantial protection against hospitalization with laboratory-confirmed influenza, mostly due to a surge in type B influenza late in the season. Vaccine coverage was low, even among groups targeted for vaccination, and considerable effort should be made to improve it. J. Med. Virol. 88:1896-1904, 2016. © 2016 Wiley Periodicals, Inc.

Clostridium difficile infection: New insights into therapeutic options.

Clostridium difficile infection (CDI) is an important cause of mortality and morbidity in healthcare settings and represents a major social and economic burden. The major virulence determinants are large clostridial toxins, toxin A (TcdA) and toxin B (TcdB), encoded within the pathogenicity locus. Traditional therapies, such as metronidazole and vancomycin, frequently lead to a vicious circle of recurrences due to their action against normal human microbiome. New disease management strategies together with the development of novel therapeutic and containment approaches are needed in order to better control outbreaks and treat patients. This article provides an overview of currently available CDI treatment options and discusses the most promising therapies under development.

The controversial impact of B cells subsets on immune response to pneumococcal vaccine in HIV-1 patients.

BACKGROUND: Chronic HIV infection leads to severe perturbations of the B cell populations and hypo-responsiveness to vaccines. The associations between circulating B cell subpopulations and the antibody response to pneumococcal polysaccharide vaccine in antiretroviral-naïve and treated patients were studied. METHODS: Sixty-six HIV-infected adults were grouped according to antiretroviral therapy (ART) and CD4+ cell count; 31 were ART-naïve and 35 were ART-treated, and they were matched for age, CD4 cell count, and duration of HIV infection. All subjects were immunized with the 23-valent polysaccharide vaccine against Streptococcus pneumoniae. Pre- and post-vaccination B cell subpopulations were assessed by flow cytometry. Serum IgG concentrations for vaccine serotypes were quantified by ELISA at baseline and at 4 and 48 weeks post-vaccination. RESULTS: Patients under highly active antiretroviral therapy (HAART) had significantly higher antibody levels against pneumococcal vaccine antigens, while an adequate number of patients responded to vaccination. Memory B cells were diminished over time, although treated patients maintained higher levels of all subsets studied, with the exception of activated memory and isotype-switched memory B cells. CONCLUSIONS: Low concentrations of total B cells and exhausted memory B cells was the strongest independent predictor of poor pneumococcal vaccine responsiveness, emphasizing that B cell subset disturbances are associated with a poor vaccine response among HIV-infected patients.

Challenges in antigenic characterization of circulating influenza A(H3N2) viruses during the 2011-2012 influenza season: an ongoing problem?

Genetic and antigenic characterization of 37 representative influenza A(H3N2) virus strains isolated in Greece during the 2011-2012 winter season was performed to evaluate matching of the viruses with the seasonal influenza vaccine strain A/Perth/16/2009. Hemagglutinin gene sequence analysis revealed that all Greek strains clustered within the Victoria/208 genetic clade. Furthermore, substitutions in the antigenic and glycosylation sites suggested potential antigenic drift. Our hemagglutination inhibition (HI) analysis showed that the Greek viruses were Perth/16-like; however, these viruses were characterized as Victoria/208-like when tested at the United Kingdom WHO Collaborating Centre (CC) with HI assays performed in the presence of oseltamivir, a finding consistent with the genetic characterization data. Variability in the HI test performance experienced by other European laboratories indicated that antigenic analysis of the A(H3N2) virus has limitations and, until its standardization, national influenza reference laboratories should include genetic characterization results for selection of representative viruses for detailed antigenic analysis by the WHO CCs.

Detection of the tetM resistance determinant among phenotypically sensitive Ureaplasma species by a novel real-time PCR method.

The study aimed to identify the proportion of tetM-positive Ureaplasma spp. isolates phenotypically susceptible to tetracycline by real-time PCR. Ureaplasma spp. strains of urogenital origin were isolated from 100 female or male adults on A7 agar plates. The presence of Ureaplasma was confirmed by the presence of urease gene by a novel real-time PCR method. Genotyping and sensitivity to tetracyclines were examined using commercial methods. The tetM gene was detected by a novel real-time PCR method especially designed for this study. Ureaplasma parvum was isolated from 87 of the specimens; Ureaplasma urealyticum, from 12; and both species were isolated from a single specimen. All isolates were phenotypically susceptible to tetracyclines. Thirty-five strains were tetM carriers; 29 (82.9%), U. parvum; 5 (14.3%), U. urealyticum; and 1 (2.9%), U. parvum/U. urealyticum. No statistically significant difference was observed between the 3 groups. Four (40%) tetM carriers were isolated from 10 symptomatic men; 11 (32.4%), from 34 symptomatic women; and 20 (35.7%), from 56 asymptomatic women. No statistically significant difference was observed between the 3 groups. The tetM determinant is detected in 35% of phenotypically susceptible to tetracycline Ureaplasma spp. Greek isolates. The use of a real-time PCR technique is particularly helpful, as it makes its detection easy; cost-effective; rapid; and, therefore, more convenient for the surveillance of the dissemination of the tetM resistance gene.

Influenza vaccine effectiveness against laboratory confirmed influenza in Greece during the 2013-2014 season: a test-negative study.

BACKGROUND: In 2013-2014 Greece experienced a resurgence of severe influenza cases, coincidental with a shift to H1N1pdm09 predominance. We sought to estimate Vaccine Effectiveness (VE) for this season using available surveillance data from hospitals (including both inpatients and outpatients). METHODS: Swab samples were sent by hospital physicians to one of three laboratories, covering the entire country, to be tested for influenza using RT-PCR. The test-negative design was employed, with patients testing positive serving as cases and those testing negative serving as controls. VE was estimated using logistic regression, adjusted for age group, sex, region and calendar time, with further adjustment for unknown vaccination status using inverse response propensity weights. Additional age group stratified estimates and subgroup estimates of VE against H1N1pdm09 and H3N2 were calculated. RESULTS: Out of 1310 patients with known vaccination status, 124 (9.5%) were vaccinated, and 543 patients (41.5%) tested positive for influenza. Adjusted VE was 34.5% (95% CI: 4.1-55.3%) against any influenza, and 56.7% (95% CI: 22.8-75.7%) against H1N1pdm09. VE estimates appeared to be higher for people aged 60 and older, while in those under 60 there was limited evidence of effectiveness. Isolated circulating strains were genetically close to the vaccine strain, with limited evidence of antigenic drift. CONCLUSIONS: These results suggest a moderate protective effect of the 2013-2014 influenza vaccine, mainly against H1N1pdm09 and in people aged 60 and over. Vaccine coverage was very low in Greece, even among groups targeted for vaccination, and substantial efforts should be made to improve it. VE can and should be routinely monitored, and the results taken into account when deciding on influenza vaccine composition for next season.

Molecular epidemiology of noroviruses in Northern Greece, 2005-2006.

Noroviruses (NoVs) are important human pathogens associated with acute viral gastroenteritis worldwide, displaying significant genetic heterogeneity. Genotype GII.4 is responsible for the majority of outbreaks reported to date. A total of 460 faecal samples from sporadic gastroenteritis cases were screened for the presence of NoV RNA. Four additional human samples collected during a waterborne NoV gastroenteritis outbreak observed in 2005 in northern Greece, were also included in the study. All PCR-positive samples were tested further using a multiplex RT-PCR, which targets the viral capsid VP1 region D. PCR products from all outbreak samples and from 20 randomly selected samples were sequenced. Phylogenetic analysis revealed that GII.4 genotype predominated (70%), while genotypes GII.2 (10%), GII.7 (15%), and GI.1 (5%) were also detected. All the outbreak NoV strains belonged to the GI.1 genotype. The present study provides a first insight into the epidemiology and genetic diversity of NoVs in Greece and shows that various strains are circulating in the country and cause sporadic cases or outbreaks.

Genetic analysis of post-pandemic 2010-2011 influenza A(H1N1)pdm09 hemagglutinin virus variants that caused mild, severe, and fatal infections in Northern Greece.

Since its appearance, influenza A(H1N1)pdm09 caused considerable morbidity and mortality in Northern Greece. Genetic analysis of post-pandemic circulating strains scoped to investigate any correlation between genetic variations that emerged during viral evolution and severity of infection. Pharyngeal swabs/aspirates (n = 1,870) were examined with real-time reverse transcription-polymerase chain reaction. Hemagglutinin sequences were analyzed on 110 strains (37 fatal/73 non-fatal cases), followed by statistical and phylogenetic analysis. Influenza A(H1N1)pdm09 was detected in 848 samples. Coexistence of clusters 3, 4, 5, 6, and 7 indicated co-circulation of lineages in Northern Greece. Genetic analysis showed that HA sequences had 96-99% sequence similarity with the vaccine strain and that there was no association between any co-circulating lineage and severity. Several viruses accumulated variations in HA antigenic sites. D222G was significantly associated with fatal infections, supporting its association with increased viral pathogenesis. On the other hand, four variations were associated with milder disease outcomes. Certain signature amino acid changes persisted during and/or after the pandemic, indicating their offer of selective advantages to the virus. Negative selection was observed in 70% of pandemic variations as they probably did not contribute to the virus fitness. It is of interest that persistent variations were highly identified in the vicinity of antigenic or receptor-binding sites. Of those, K171R was associated only with fatal infections. Also of interest, only strains that were isolated from fatal infections had variations that altered both their acid-base and polarity properties. Genetic changes that may alter the antigenicity, pathogenicity and transmissibility of circulating virus variants need to be determined and closely monitored.

Older HIV-infected patients--an underestimated population in northern Greece: epidemiology, risk of disease progression and death.

OBJECTIVES: HIV prevalence among older people is on the increase. The aim of this study was to evaluate the epidemiological and clinical features at diagnosis and survival of older patients. METHODS: This was a retrospective analysis of the data of 558 newly diagnosed antiretroviral-naïve patients between January 1998 and December 2008. Patients were divided into two groups according to their age at diagnosis: ≥50 years (n=103) and 18-49 years (n=455). RESULTS: The most common risk factor for older patients was heterosexual contact (p<0.013). Older patients were more likely to suffer from hypertension (33.0% vs. 5.1%, p<0.0005), cardiovascular disease (20.4% vs. 2.9%, p<0.0005), neurological disorders (11.7% vs. 5.5%, p=0.02), renal dysfunction (12.6% vs. 5.3%, p=0.01), and infections (66.0% vs. 49.7%, p=0.003) than their younger counterparts, and to have more hospital admissions during follow-up (47.5% vs. 19.6%, p<0.0005). Older patients had a shorter survival time (p<0.0005). A statistically significant increase in CD4+ cell number through time was observed in both groups (p<0.0005). Younger patients reached higher magnitudes of absolute numbers of CD4+ cells during follow-up (p<0.0005) after the initiation of antiretroviral therapy. The total number of patients with clinical AIDS from baseline throughout the study period was also higher in the older age group (35.9% vs. 25.0%). CONCLUSIONS: HIV-infected people aged ≥50 years differ in epidemiological and clinical features to younger HIV-infected people. The issue of increasing prevalence of HIV infection is a matter of concern due to existing comorbidities, which probably lead to higher mortality rates and faster progression to clinical AIDS.

Vascular access malfunction: towards a more genecentric view.

A well-functioning vascular access is the cornerstone for an optimal hemodialysis treatment and an issue of major importance for the outcome of patients on chronic hemodialysis. Over the last few years reports supporting the aspect that mechanisms involved in vascular access malfunction are genetically controlled have been published. Triggered by two cases reported herein, we present a comprehensive review of the literature on an evolving field of particular significance to patients on hemodialysis.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Molecular and epidemiological characterization of HIV-1 infection networks involving transmitted drug resistance mutations in Northern Greece.

OBJECTIVES: To determine the contribution of transmission clusters to transmitted drug resistance (TDR) in newly diagnosed antiretroviral-naive HIV-1-infected patients in Northern Greece during 2000-07. METHODS: The prevalence of TDR was estimated in 369 individuals who were diagnosed with HIV-1 infection in the period 2000-07 at the National AIDS Reference Laboratory of Northern Greece. Phylogenetic analysis was performed using a maximum likelihood method on partial pol sequences. TDR was defined in accordance with the surveillance drug resistance mutation list (2009 update). RESULTS: The overall prevalence of TDR in our population was 12.5% [46/369, 95% confidence interval (CI) 9.1%-15.8%], comprising 7.6% (28/369) resistant to nucleoside reverse transcriptase inhibitors, 5.4% (20/369) resistant to non-nucleoside reverse transcriptase inhibitors and 3.3% (12/369) resistant to protease inhibitors. Dual class resistance was identified in 3.8% (14/369). Infection with subtype A was the sole predictor associated with TDR in multivariate analysis (odds ratio 2.15, 95% CI 1.10-4.19, P = 0.025). Phylogenetic analyses revealed three statistically robust transmission clusters involving drug-resistant strains, including one cluster of 12 patients, 10 of whom were infected with a strain carrying both T215 revertants and Y181C mutations. CONCLUSIONS: Our findings underline the substantial impact of transmission networks on TDR in our population.

Clostridium difficile infection: a comprehensive review.

Clostridium difficile is one of the most important causes of healthcare acquired diarrhea. The disease spectrum caused by C. difficile infection ranges from mild, self-limited, illness to a severe, life-threatening colitis. The incidence of C. difficile associated disease has risen dramatically over the last decade, leading to increased research interest aiming at the discovery of new virulence factors and the development of new treatment and prevention regimens. This review summarizes the pathogenesis and changing epidemiology of C. difficile associated disease, the clinical spectrum and laboratory methods to diagnose C. difficile infection, and current treatment strategies.

Molecular and phylogenetic analysis of the haemagglutinin gene of pandemic influenza H1N1 2009 viruses associated with severe and fatal infections.

The objectives of this research is molecular and phylogenetic analysis of pandemic influenza A(H1N1) 2009 strains that circulated in northern Greece, focusing on severe or fatal infections, identification of sequence variations in relation with the severity of the illness and comparison of circulating viruses with the vaccine strain. A total of 1598 infections were attributed to the novel influenza A(H1N1) virus. Molecular analysis revealed a number of variations at the HA1 sequences of northern Greek circulating strains, some of which were more frequent in viruses that caused severe or fatal infections. Such mutations, the most common being D222G, demand close monitoring to continuously assess associated risks. Phylogenetic analysis confirmed the close match of the majority of circulating strains with A/California/7/09. However it also reveals a trend of 2010 strains to accumulate amino acid variations and form new plylogenetic clades. Constant molecular surveillance is important to monitor the pathogenicity of circulating strains and evaluate the vaccine efficacy.