The impact of COVID-19 pandemic control on vaccine-preventable invasive bacterial diseases in Piedmont (Italy).

PURPOSE: The impact of SARS-CoV-2 pandemic on other pathogens is largely unknown. We aimed to compare the prevalence of vaccine-preventable invasive bacterial infections before and during the pandemic in Piedmont (Italy). METHODS: We defined the monthly incidence of S. pneumoniae, H. influenzae and N. meningitides-invasive diseases from January 2010 to June 2021. Then, we compared the mean monthly cases during the previous 5 years (2015-2019) and the monthly cases in 2020 or 2021. RESULTS: We found significant reductions for invasive pneumococcal diseases (IPDs) in adults and H. influenzae-invasive diseases in 2020 and 2021 in comparison to the previous years, but not for invasive meningococcal diseases and IPDs in children. CONCLUSIONS: Further data are needed to confirm these findings and define possible post-pandemic evolutions in the epidemiology of vaccine-preventable invasive bacterial diseases.

Safety and outcomes of routine endovascular thrombectomy in large artery occlusion recorded in the SITS Register: An observational study.

BACKGROUND AND OBJECTIVE: We aimed to evaluate the safety and outcomes of thrombectomy in anterior circulation acute ischaemic stroke recorded in the SITS-International Stroke Thrombectomy Register (SITS-ISTR) and compare them with pooled randomized controlled trials (RCTs) and two national registry studies. METHODS: We identified centres recording ≥10 consecutive patients in the SITS-ISTR with at least 70% of available modified Rankin Scale (mRS) at 3 months during 2014-2019. We defined large artery occlusion as intracranial internal carotid artery, first and second segment of middle cerebral artery and first segment of anterior cerebral artery. Outcome measures were functional independence (mRS score 0-2) and death at 3 months and symptomatic intracranial haemorrhage (SICH) per modified SITS-MOST. RESULTS: Results are presented in the following order: SITS-ISTR, RCTs, MR CLEAN Registry and German Stroke Registry (GSR). Median age was 73, 68, 71 and 75 years; baseline NIHSS score was 16, 17, 16 and 15; prior intravenous thrombolysis was 62%, 83%, 78% and 56%; onset to reperfusion time was 289, 285, 267 and 249 min; successful recanalization (mTICI score 2b or 3) was 86%, 71%, 59% and 83%; functional independence at 3 months was 45.5% (95% CI: 44-47), 46.0% (42-50), 38% (35-41) and 37% (35-41), respectively; death was 19.2% (19-21), 15.3% (12.7-18.4), 29.2% (27-32) and 28.6% (27-31); and SICH was 3.6% (3-4), 4.4% (3.0-6.4), 5.8% (4.7-7.1) and not available. CONCLUSION: Thrombectomy in routine clinical use registered in the SITS-ISTR showed safety and outcomes comparable to RCTs, and better functional outcomes and lower mortality than previous national registry studies.

Ceftazidime-avibactam resistance and restoration of carbapenem susceptibility in KPC-producing Klebsiella pneumoniae infections: A case series.

OBJECTIVES: Since the introduction of the ß-lactam/ß-lactamase inhibitor ceftazidime-avibactam (CZA), rapid evolution of resistance has been reported in different KPC-producing Klebsiella pneumoniae isolates. In this multicenter retrospective study, we describe the emergence of CZA resistance and evaluate the mutations that might be responsible for the restoration of carbapenem susceptibility. METHODS: During a study period of 18 months, KPC-producing K. pneumoniae isolates of five hospitalized patients were collected with phenotypic development of CZA resistance. RESULTS: In vitro restoration of carbapenem susceptibility during treatment was observed in 3 isolates. Whole genome sequencing of these isolates showed a D179Y mutation in the KPC gene of 2 variants and a KPC-2 with a Δ242-GT-243 deletion (KPC-14). Two KPC-3 variants showed CZA resistance with sustained carbapenemase activity without genomic adaptations in the KPC gene. CONCLUSIONS: This study confirms the emergence of CZA resistance in KPC K. pneumoniae. The role of carbapenems in treating patients with these variants is unclear and combination therapies warrant further investigation.

Grain-size-independent plastic flow at ultrahigh pressures and strain rates.

A basic tenet of material science is that the flow stress of a metal increases as its grain size decreases, an effect described by the Hall-Petch relation. This relation is used extensively in material design to optimize the hardness, durability, survivability, and ductility of structural metals. This Letter reports experimental results in a new regime of high pressures and strain rates that challenge this basic tenet of mechanical metallurgy. We report measurements of the plastic flow of the model body-centered-cubic metal tantalum made under conditions of high pressure (>100 GPa) and strain rate (∼10(7) s(-1)) achieved by using the Omega laser. Under these unique plastic deformation ("flow") conditions, the effect of grain size is found to be negligible for grain sizes >0.25 µm sizes. A multiscale model of the plastic flow suggests that pressure and strain rate hardening dominate over the grain-size effects. Theoretical estimates, based on grain compatibility and geometrically necessary dislocations, corroborate this conclusion.

Patients with cancer who will be cured and projections of complete prevalence in Italy from 2018 to 2030.

BACKGROUND: The number and projections of cancer survivors are necessary to meet the healthcare needs of patients, while data on cure prevalence, that is, the percentage of patients who will not die of cancer by time since diagnosis, are lacking. MATERIALS AND METHODS: Data from Italian cancer registries (duration of registration ranged from 9 to 40 years, with a median of 22 years) covering 47% of the population were used to calculate the limited-duration prevalence, the complete prevalence in 2018, projections to 2030, and cure prevalence, by cancer type, sex, age, and time since diagnosis. RESULTS: A total of 3 347 809 people were alive in Italy in 2018 after a cancer diagnosis, corresponding to 5.6% of the resident population. They will increase by 1.5% per year to 4 012 376 in 2030, corresponding to 6.9% of the resident population, 7.6% of women and ∼22% after age 75 years. In 2030, more than one-half of all prevalent cases (2 million) will have been diagnosed by ≥10 years. Those with breast (1.05 million), prostate (0.56 million), or colorectal cancers (0.47 million) will be 52% of all prevalent patients. Cure prevalence was 86% for all patients alive in 2018 (87% for patients with breast cancer and 99% for patients with thyroid or testicular cancer), increasing with time since diagnosis to 93% for patients alive after 5 years and 96% after 10 years. Among patients who survived at least 5 years, the excess risk of death (1 - cure prevalence) was <5% for patients with most cancer types except for those with cancers of the breast (8.3%), lung (11.1%), kidney (13.2%), and bladder (15.5%). CONCLUSIONS: Study findings encourage the implementation of evidence-based policies aimed at improving long-term clinical follow-up and rehabilitation of people living after cancer diagnosis throughout the course of the disease. Updated estimates of complete prevalence are important to enhance data-driven cancer control planning.

The lack of cytomegalovirus-specific cellular immune response may contribute to the onset of organ infection and disease in lung transplant recipients.

Cellular immune response has been demonstrated to play a role in the control of human cytomegalovirus (HCMV) replication in organ transplant recipients. Herein, HCMV-specific T-cell response and association to the onset of organ infection/disease were prospectively evaluated by EliSPOT assay in a population of 46 lung transplant (LT) recipients at 1, 3, 6, 9 and 12 months post-transplantation. According to our centre?s practice, a combined prolonged antiviral prophylaxis (HCMV-IG for 12 months and ganciclovir or valganciclovir for 3 weeks from postoperative day 21) was given to all LT recipients. HCMV-DNA was concomitantly detected on bronchoalveolar lavage (BAL) and whole blood by real-time PCR. Approximately one third of patients resulted HCMV persistently non-responder; the rate of HCMV infection, as evaluated by HCMV-DNA positivity, tended to be higher in non-responders. Mean viral load on BAL was significantly higher in non-responders vs other patients (p < 0.001). Temporal profile of infections appeared related to the HCMV responder status with a shorter time to onset of infection post-transplantation and a longer duration in non-responders. The occurrence of organ disease (i.e. pneumonia) tended to be higher in non-responders, with poor prognosis, as death occurred in one of three non-responder patients that developed HCMV pneumonia. The lack of HCMV-specific cellular response can contribute to the onset of organ infection and disease also in patients in which antiviral prophylaxis was adopted; this could be due to the potential occurrence of incomplete control of replication in lungs or a delayed priming of T-cell reconstitution.

Th1, Th2, Th17 and regulatory T cell pattern in psoriatic patients: modulation of cytokines and gene targets induced by etanercept treatment and correlation with clinical response.

BACKGROUND: Psoriasis is sustained by pro-inflammatory CD4+ T helper cells mainly belonging to the Th1, Th17 and Th22 lineage. OBJECTIVE: To identify whether treatment with the anti-tumour-necrosis-factor antagonist etanercept is able to induce significant modulations in transcription factor and cytokine mRNA gene expressions related to the different T cell immune response polarization (Th1, Th2, Th17 and regulatory T cells, Treg and to correlate them with clinical response. METHODS: The study population included 19 psoriasis patients treated with etanercept and 19 healthy subjects. Blood samples were collected at baseline and every 4 weeks during treatment. Taqman quantitative real-time polymerase chain reaction was applied to analyse the expression of: Stat-4, T-bet, IL-12p35 and IFN-γ (Th1-related); GATA-3, IL-4 (Th2-related); Stat-3, RORγt, IL-23p19 (Th17-related); Foxp3, IL-2 (Treg-related). Flow cytometry was applied to analyse CD4+CD25+(bright)Foxp3+ cells in peripheral blood. RESULTS: Upregulation of Th1 and Th17 and downregulation of Treg subsets was found at baseline. The response to etanercept could be associated with a significant reversal of the Th1/Th17 activation, and a concomitant upregulation of Th2 and Treg subsets. CONCLUSION: Our data may contribute to a better understanding of the mechanisms underlying the achievement of clinical response in psoriasis and could be helpful for the identification of early predictive markers of response.

Detection of the novel variant of influenza virus A/H1N1v in bronchoalveolar lavage of adult hospitalized patients during the 2009/2010 winter season.

AIM: The aim of this study was to report most recent data regarding the occurrence of influenza A virus H1N1v in the lower respiratory tract from a cohort of hospitalized adult patients during the winter season 2009/2010 and investigated the main clinical features and outcomes. METHODS: A total of 130 consecutive BAL specimens (collected from October 2009-March 2010) of 101 patients were retrospectively analyzed for influenza A virus H1N1v positivity using a commercial kit. RESULTS: Overall, 19/130 (14.6%) BAL specimens from 17/101 (16.8%) patients were positive for the novel influenza A H1N1v virus. H1N1v resulted significantly more prevalent in immunocompetent subjects. As regards clinical features, H1N1v resulted more prevalent in respiratory insufficiency or acute respiratory illness. Thirteen patients died during the analytic period; three of them (23.1%) resulted positive to H1N1v but no direct association has been made. CONCLUSION: Our cohort study of influenza A H1N1v detection in BAL from hospitalized adult patients confirms the overall moderate clinical impact of this virus, as reported in most reports worldwide. It remains to be evaluated the role of reassortment with influenza virus strains circulating in the winter season 2010/2011 and its potential pathogenicity.

Integrating rapid diagnostics in Gram-negative bloodstream infections of patients colonized by carbapenemase-producing Enterobacterales.

We implemented a fast-track diagnostic approach for Gram-negative bloodstram infections (BSIs) among carbapenemase-producing Enterobacterales (CPE) carriers. Within a large cohort of patients with CPE rectal carriage, 18.1% developed Gram-negative BSIs, of which 69.5% were caused by CPE. Direct matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis provided reliable identification in 97% and 53.8% of monomicrobical blood cultures positive to Enterobacterales and non-fermenting Gram-negative species, respectively. Overall, sensitivity and specificity of NG-Test Carba 5 compared with the composite reference method after discrepant analysis were 100%, in polimicrobial blood cultures too. The combined use of direct MALDI-TOF MS and NG-Test Carba 5 assay might be a reliable and cost-effective tool for accelerating the laboratory diagnosis of CPE BSI in cohorts of high-risk patients such as CPE carriers.

Concomitant chemoradiotherapy versus induction docetaxel, cisplatin and 5 fluorouracil (TPF) followed by concomitant chemoradiotherapy in locally advanced head and neck cancer: a phase II randomized study.

BACKGROUND: Concomitant chemoradiotherapy (CT/RT) is the standard treatment of locally advanced squamous cell carcinoma of the head and neck (SCCHN). We evaluated the efficacy of induction docetaxel (Taxotere), cisplatin, and 5-fluorouracil (TPF) before CT/RT versus CT/RT alone. PATIENTS AND METHODS: Patients with stage III-IVM0 SCCHN, Eastern Cooperative Oncology Group performance status of zero to one, were randomly assigned to receive CT/RT alone (arm A: two cycles of cisplatin 20 mg/m(2), days1-4, plus 5-fluorouracil 800 mg/m(2)/day 96 h continuous infusion, during weeks 1 and 6 of radiotherapy) or three cycles of TPF (arm B: docetaxel 75 mg/m(2) and cisplatin 80 mg/m(2), day 1, and 5-fluorouracil 800 mg/m(2)/day 96 h continuous infusion, every 3 weeks) followed by the same CT/RT. The primary end point was the rate of radiologic complete response (CR) at 6-8 weeks after the end of CT/RT. RESULTS: A total of 101 patients were randomly allocated to the study (51 arm A; 50 arm B). CR rates were 21.2% (arm A) versus 50% (arm B). Median progression-free survival and overall survival were, respectively, 19.7 and 33.3 months (arm A) and 30.4 and 39.6 months (arm B). Hematologic and non-hematologic toxic effects during CT/RT were similar in the two arms. CONCLUSION: Induction TPF followed by CT/RT was associated with higher radiologic CR in patients with locally advanced SCCHN with no negative impact on CT/RT feasibility.

Viscous Rayleigh-Taylor instability experiments at high pressure and strain rate.

Experimental results showing significant reductions from classical in the Rayleigh-Taylor instability growth rate due to high pressure effective lattice viscosity are presented. Using a laser created ramped drive, vanadium samples are compressed and accelerated quasi-isentropically at approximately 1 Mbar peak pressures, while maintaining the sample in the solid state. Comparisons with simulations and theory indicate that the high pressure, high strain rate conditions trigger a phonon drag mechanism, resulting in the observed high effective lattice viscosity and strong stabilization of the Rayleigh-Taylor instability.

Prevalence of polyomaviruses BK, JC, SV40, KI, and WU in non-malignant tonsil specimens.

AIM: The recently described polyomaviruses KI and WU have been detected in respiratory samples, stools, tonsils, and blood, particularly in immunocompromised conditions, although little is known about tissue tropism. Herein we investigated the occurrence of KIV and WUV in non-malignant tonsillar specimens by Real-time quantitative PCR; the presence of polyomaviruses BK, JC and SV40-DNA was also evaluated. METHODS: Twenty-nine non-malignant tonsil specimens obtained from children and adults admitted for tonsillectomy were prospectively studied. Real-time quantitative TaqMan PCR for polyomaviruses KI, WU, BK, JC, and SV40 were performed. RESULTS: KI-DNA was positive in 2/29 tonsillar specimens (6.9%), while BK- DNA, JC-DNA, SV-40 DNA, and WU-DNA sequences were not identified. CONCLUSION: Few studies have investigated the prevalence of polyomaviruses in tonsil specimens, with varying results, and data are particularly scant as regards the newly discovered KIV and WUV. Two major questions remain to be definitely answered at this regard: the possibility that human tonsils represent the initial site of infection and/or a latency site and the biological and clinical meaning of KIV and WUV in different contexts and groups of patients, in that it is not clear whether they are simple bystanders or play a role in tonsil disease.

Reduction of turnaround time for non-tuberculous mycobacteria detection in heater-cooler units by propidium monoazide-real-time polymerase chain reaction.

BACKGROUND: Invasive non-tuberculous mycobacteria (NTM) infections are emerging worldwide in patients undergoing open-chest cardiac bypass surgery exposed to contaminated heater-cooler units (HCUs). Although this outbreak has been investigated by culturing bacteria isolated from HCU aerosol and water samples, these conventional methods have low-analytic sensitivity, high rates of sample contamination, and long turnaround time. AIM: To develop a simple and effective method to detect NTM in HCUs by real-time polymerase chain reaction (PCR), with a short laboratory turnaround time and reliable culture results. METHODS: A total of 281 water samples collected from various HCUs at seven Italian hospitals were simultaneously screened for NTM by a propidium monoazide (PMA)-PCR assay and by conventional culture testing. The results were analysed with culture testing as the reference method. FINDINGS: (i) The agreement between culture testing and PMA-PCR was 85.0% with a cycle threshold (CT) cut-off value of <38 vs 80.0% with a CT of <43, with a moderate Cohen's κ-coefficient; (ii) the CT cut-off value of <42 was deemed more suitable for predicting positive specimens; (iii) given the low concentration of target DNA in water samples, the minimum volume to be tested was 1 L. CONCLUSION: The use of PMA-PCR for fast detection of NTM from environmental samples is highly recommended in order to ascertain whether HCUs may represent a potential source of human exposure to NTM. This reliable and simple method reduces laboratory turnaround time compared to conventional methods (one to two days vs eight weeks, respectively), thereby improving control strategies and effective management of HCUs.

Accuracy of the ELITe MGB assays for the detection of carbapenemases, CTX-M, Staphylococcus aureus and mecA/C genes directly from respiratory samples.

INTRODUCTION: Bacterial lower respiratory tract infections (BLRTI) may represent serious clinical conditions which can lead to respiratory failure, intensive care unit admission and high hospital costs. The detection of carbapenemase- and extended-spectrum ß-lactamase (ESBL)-producing Enterobacterales, as well as meticillin-resistant Staphylococcus aureus (MRSA), has become a major issue, especially in healthcare-associated infections. This study aimed to determine whether molecular assays could detect genes encoding carbapenemases, ESBL and MRSA directly from respiratory samples in order to expedite appropriate therapy and infection control for patients with BLRTI. METHODS: The carbapenem-resistant enterobacterales (CRE), ESBL and MRSA/SA ELITe MGB assays were performed directly on 354 respiratory specimens sampled from 318 patients admitted with BLRTI. Molecular results were compared with routine culture-based diagnostics results. RESULTS: Positive (PPV) and negative (NPV) predictive values of the CRE ELITe MGB kit were 75.9% [95% confidence interval (CI) 60.3-86.7] and 100%, respectively. PPV and NPV of the ESBL ELITe MGB kit were 80.8% (95% CI 63.6-91.0) and 99.1% (95% CI 96.6-99.8), respectively. PPV and NPV of the MRSA/SA ELITe MGB kit were 91.7% (95% CI 73.7-97.7)/100% and 98.3% (95% CI 89.8-99.3)/96.8% (95% CI 81.6-99.5), respectively. DISCUSSION: Validity assessment of molecular assays detecting the main antibiotic resistance genes directly from respiratory samples showed high accuracy compared with culture-based results. Molecular assays detecting the main carbapenemase, ESBL, S. aureus and meticillin resistance encoding genes provide an interesting tool with potential to expedite optimization of antibiotic therapy and infection control practices in patients with BLRTI.

Antibiotic Resistance and Therapy Outcome in H. pylori Eradication Failure Patients.

Helicobacter pylori (H. pylori) eradication fails in a definite amount of patients despite one or more therapeutic attempts. Curing these patients is progressively more difficult, due to development of antibiotic resistance. Current guidelines suggest testing antibiotic susceptibility in H. pylori isolates following two therapeutic attempts. AIM: to evaluate the development of antibiotic resistance, MIC values trends and therapeutic outcomes in patients who failed at least one H. pylori eradication therapy. METHODS: consecutive patients, referred to perform upper gastrointestinal endoscopy (UGIE) to our Unit from January 2009 to January 2019 following at least one therapeutic attempt were considered. Bacterial resistance towards clarithromycin, metronidazole and levofloxacin was tested. Patients received either a susceptibility-guided therapy or Pylera®. RESULTS: a total of 1223 patients were H. pylori positive, and antibiotic susceptibility was available for 1037. The rate of antibiotic resistance and MIC values significantly increased paralleling the number of previous therapeutic attempts. Eradication rates of antibiogram-tailored therapies remained stable, except for the sequential therapy if used as a third line. As a rescue treatment, the Pylera® therapy achieved cure rates comparable to those of the other culture-guided therapies. CONCLUSIONS: A significant increase in the secondary resistance towards the three tested antibiotics was observed, both as rate and MIC values, in correlation with the number of therapy failures. These findings should be considered when administering an empirical second-line therapy. Pylera® therapy eradication rates are comparable to culture-tailored therapies.

RESIST-5 O.O.K.N.V. and NG-Test Carba 5 assays for the rapid detection of carbapenemase-producing Enterobacterales from positive blood cultures: a comparative study.

We prospectively compared the performance of RESIST-5 O.O.K.N.V. and NG-Test Carba 5 assays directly from blood cultures spiked with 130 characterized Enterobacterales isolates. Overall, both assays yielded 100% sensitivity to detect KPC-type carbapenemases and OXA-48-like carbapenemases. Both assays failed to detect KPC-31 and KPC-33, D179Y point mutation variants of KPC-3 and KPC-2, that are deprived of carbapenemase activity and confer resistance to ceftazidime-avibactam. On blood culture bacterial pellets, NDM- and VIM-type carbapenemases were detected in 50.0% and 52.2%, respectively, by RESIST-5 O.O.K.N.V. vs 100% by NG-Test Carba 5. The sensitivity of RESIST-5 O.O.K.N.V. improved to 100% and 95.6%, respectively, by performing the assay on 4-h early subculture.

delta-catenin, an adhesive junction-associated protein which promotes cell scattering.

The classical adherens junction that holds epithelial cells together consists of a protein complex in which members of the cadherin family linked to various catenins are the principal components. delta-catenin is a mammalian brain protein in the Armadillo repeat superfamily with sequence similarity to the adherens junction protein p120(ctn). We found that delta-catenin can be immunoprecipitated as a complex with other components of the adherens junction, including cadherin and beta-catenin, from transfected cells and brain. The interaction with cadherin involves direct contact within the highly conserved juxtamembrane region of the COOH terminus, where p120(ctn) also binds. In developing mouse brain, staining with delta-catenin antibodies is prominent towards the apical boundary of the neuroepithelial cells in the ventricular zone. When transfected into Madin-Darby canine kidney (MDCK) epithelial cells delta-catenin colocalized with cadherin, p120(ctn), and beta-catenin. The Arm domain alone was sufficient for achieving localization and coimmunoprecipitation with cadherin. The ectopic expression of delta-catenin in MDCK cells altered their morphology, induced the elaboration of lamellipodia, interfered with monolayer formation, and increased scattering in response to hepatocyte growth factor treatment. We propose that delta-catenin can regulate adhesion molecules to implement the organization of large cellular arrays necessary for tissue morphogenesis.

Lower respiratory tract viral infections in hospitalized adult patients.

AIM: The epidemiology of lower respiratory tract (LRT) viral infections in adults is probably underestimated and the high frequency of multiple viral infections complicates the evaluation of the possible role of the single viruses. The aim of this study was to investigate the clinical epidemiology and impact of respiratory viral pathogens, in particular of those singularly detected, in bronchoalveolar lavage (BAL) specimens from hospitalized adult patients. METHODS: A panel for the detection of 16 respiratory viruses was used to prospectively evaluate 324 consecutive specimens obtained from 219 patients over a full-year period. RESULTS: Two-hundred-twenty-one specimens (68.2%) were positive for at least one virus, 119/324 (36.7%) to a single viral agent. The most commonly detected viruses were herpesviruses HHV-7 (26.2%), human cytomegalo-virus (HCMV, 22.2%), HHV-6 (19.8%), EBV (12.7%), enteroviruses and rhinoviruses (both 11.7%), parainfluenza viruses (4.9 %), and metapneumovirus (4.0%). Human cytomegalo-virus was significantly more prevalent as single viral pathogen with a viral load >105 copies/ml associated to pneumonia in solid organ transplant recipients. Other viral pathogens might account for some cases of pneumonia or respiratory insufficiency, although multiple infections were common. CONCLUSIONS: The use of a comprehensive diagnostic panel for respiratory viral infections may be useful to clarify the epidemiology and clinical impact of viral pathogens in hospitalized adult patients. The occurrence of multiple infections is a common finding and results should be interpreted taking into account the clinical context as well as viral load and the biological characteristics of each virus.

Culturable heterotrophic bacteria in seawater and Mytilus galloprovincialis from a Mediterranean area (Northern Ionian Sea-Italy).

Although Mar Piccolo of Taranto (Ionian Sea, Italy) is one of the most important Mytilus galloprovincialis farming areas, data concerning the natural bacterial microbiota of these mussels and their surrounding environment are still scant. This study was carried out seasonally, throughout a year, to determine culturable heterotrophic bacteria both in the water and mussels samples collected at three sampling sites in the Northern Ionian Sea: S. Vito, Lido Gandoli and Lido Silvana. Culturable heterotrophic bacteria abundance was determined by spread plate on Marine Agar. Heterotrophic bacteria were identified by several morphological, culture and biochemical methods. Bacterial concentrations were higher in the mussel samples compared to the corresponding seawater throughout the year. Among Gram negative heterotrophic bacteria, Aeromonas prevailed both in the water (18%) and mussel samples (40%). Other genera such as Moraxella, Pseudomonas, Alcaligenes, Acinetobacter, Flavobacterium, Chromobacterium, Photobacterium and Flexibacter were present with different percentages of isolation. Bacilli were predominant among Gram positive bacteria. Some genera (Lucibacterium and Vibrio) were present only in mussel samples. The results obtained contribute to improve the knowledge on both the bacterial abundance and diversity in mussels and the surrounding seawater in the Northern Ionian Sea.