Efficacy and safety of ceftazidime-avibactam compared to other antimicrobials for the treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae strains, a systematic review and meta-analysis.

INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a significant public health issue. CRKP infections can increase the mortality of severely ill hospitalised patients and elevate the financial burden of their hospitalisation globally. Colistin and tigecycline are the main antimicrobials which have been widely used for the treatment of CRKP infections. However, novel antimicrobials have been recently launched. Ceftazidime-avibactam (CAZ-AVI) seems one of the most efficient ones. AIM: The aim of the current systematic literature review and meta-analysis is to assess the efficacy and safety of CAZ-AVI compared to other antimicrobials in adult patients (aged >18) with CRKP infection. METHODS: All data were retrieved using PubMed/Medline, the Web of Science and Cochrane library. The main outcome was the effective treatment of CRKP infection or the microbiological eradication of CRKP in the culture of biological samples. Secondary outcomes included the impact on 28- or 30-day mortality and adverse effects, if available. Pooled analysis was conducted using Review Manager v. 5.4.1 software (RevMan). The level of statistical significance was set at p < 0.05. RESULTS: CAZ-AVI was proved more effective than other antimicrobials against CRKP infections and CRKP bloodstream infections (p < 0.00001 and p < 0.0001, respectively). Patients in the CAZ-AVI arm displayed statistically lower 28- and 30-day mortality rates (p = 0.002 and p < 0.00001, respectively). Concerning the microbiological eradication, no meta-analysis was feasible due to high heterogeneity. CONCLUSION: The promotion of CAZ-AVI for treating CRKP infections over other antimicrobials seems favourable. However, there is a long way ahead to reveal additional scientific findings to further strengthen this statement.

Spa diversity and genetic characterization of t127 methicillin-resistant Staphylococcus aureus in a tertiary Greek hospital.

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) causes severe community and hospital acquired infections. Identification of staphylococcal cassette chromosome mec (SCCmec), multilocus-sequence typing, and sequencing of S. aureus protein A (spa) gene are used for MRSA typing. The aim was to investigate the spa types of MRSA isolates in a tertiary hospital in Greece and analyse the whole genome sequences of two t127 MRSA isolates. Methods: Totally, 39 MRSA isolates collected from July 2019 to June 2020 in "Georgios Gennimatas" General Hospital of Thessaloniki, Greece, were included in the study. Identification and antimicrobial susceptibility testing were performed using VITEK II automated system, and spa typing was performed. A minimum spanning tree was used to display the spa type frequencies and the genetic distances among them. Two t127-MRSA isolates (IM-MRSA and PD-MRSA) were selected for WGS. Results: Six isolates (15.4%) were resistant to mupirocin, 18 (46.2%) to fusidic acid, three (7.7%) to vancomycin and two (5.1%) to teicoplanin. Twenty-two different spa types were detected, with t002, t003, and t422 being the most frequent (5/39, 12.8% each), followed by t1994 (4/39, 10.3%). The isolates presented high genetic diversity and, taking into account the time between hospital admission and sampling, intrahospital spread did not occur. Even the two t127 isolates were assigned to different sequence types, ST9-XII-t127 and ST1-IVa-t127. Plasmids and genes conferring antimicrobial resistance and virulence were also identified. Conclusions: Various spa types were identified and together with the information about the time between hospital admission and sampling supports polyclonal MRSA spread in the hospital excluding a nosocomial infection. WGS provides a more detailed analysis distinguishing even the isolates belonging to the same spa type.

Genetic characterization of two methicillin-resistant Staphylococcus aureus spa type t127 strains isolated from workers in the dairy production chain in Greece.

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes a constant threat for the public health. Aim of the present study was to analyse the whole genome sequences of two MRSA strains belonging to Staphylococcus protein A (spa) type t127 isolated from humans working in two distantly located dairy production farms in Greece.MRSA strains were isolated from the nasal cavity of a food handler in a milk industry in Epirus, northwestern Greece (E-MRSA), and a person working in a cattle farm in Thrace, northeastern Greece (T-MRSA). Whole genome sequences taken using next generation sequencing were analysed for resistance and virulence genes applying various bioinformatic tools.Both isolates were assigned to ST1-IVa-t127 type, and they were transferring genes conferring resistance to tetracycline, ß-lactams, and aminoglycosides; T-MRSA was carrying additional genes leading to macrolide, lincosamide and streptogramin B (MLSB) resistance. Both isolates were carrying three plasmid replicon types, rep5, rep7 and rep16, while T-MRSA harboured also rep10 and rep15. E-MRSA carried scn and sak genes which were absent from T-MRSA.In conclusion, the genetic characterization of two unrelated ST1-IVa-t127 MRSA strains isolated from humans in close contact with livestock in Greece can be used as basis for further epidemiological and evolutionary studies.

Respiratory Syncytial Virus in Greece, 2016-2018.

Human respiratory syncytial virus (RSV) is the leading cause of acute bronchiolitis in infants and young children. Children under the age of 2 years, hospitalized for bronchiolitis in the pediatric clinic of a tertiary hospital in northern Greece, were tested for RSV infection during two RSV seasons (2016-2017 and 2017-2018). RSV was detected in 37 of 71 (52.1%) patients, most of them younger than 6 months. Both RSV subtypes were detected - RSV-A (54.1%) and RSV-B (45.9%) - with predominance of RSV-A during the 2016-2017 and RSV-B during the 2017-2018 season. RSV-A and RSV-B sequences clustered within the ON1 and BA genotypes, respectively. Compared to the prototype strains, several amino acid substitutions were observed in the duplication region of the G gene. The study provides a first insight into the molecular epidemiology of RSV in Greece.

Polyclonal predominance of concurrently producing OXA-23 and OXA-58 carbapenem-resistant Acinetobacter baumannii strains in a pediatric intensive care unit.

We report a predominance (64.7%) of polyclonal carbapenem-resistant Acinetobacter baumannii (CRAB) strains concurrently producing OXA-23 and OXA-58 carbapenemases in a pediatric intensive care unit in an endemic area. This is the first report of emergence of such double-OXA CRAB strains in a single unit worldwide.

Cytokines as biomarkers of Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a potentially severe disease caused by CCHF virus. As in other viral hemorrhagic fevers, it is considered that the course and outcome of the disease depend on the viral load and the balance among the immune response mediators, and that a fatal outcome is the result of a "cytokine storm." The level of 27 cytokines was measured in serum samples taken from 29 patients during the acute phase of the disease. Two cases were fatal. Among survivors, significant differences between severe and non-severe cases were observed in the levels of IP-10, and MCP-1, while the levels of IL-1b, IL-5, IL-6, IL-8, IL-9, IL-10, IL-15, IP-10, MCP-1, TNF-α, and RANTES differed significantly between fatal and non-fatal cases (P < 0.05). RANTES was negatively correlated with the outcome of the disease. A striking similarity with the cytokine patterns seen in Ebola virus disease was observed. A weak Th1 immune response was seen. The viral load was positively correlated with IL-10, IP-10, and MCP-1 levels, and negatively correlated with the ratio IL-12/IL-10. Especially IP-10 and MCP-1 were significantly associated with the viral load, the severity and outcome of the disease, and they could act as biomarkers and, probably, as potential targets for treatment strategies design.

Immune response in Dobrava-Belgrade virus infections.

Dobrava-Belgrade virus (DOBV) is a hantavirus that causes a disease in humans known as hemorrhagic fever with renal syndrome. Hallmarks of hantaviral infections are increased vascular permeability due to dysregulation of the endothelial cell barrier and acute thrombocytopenia. In order to gain insight into the immune response in DOBV infections, the serum levels of 27 cytokines in 24 hospitalized Greek HFRS patients were evaluated. Compared to the control group, significantly higher IL-1ra, IL-6, IL-8, IL-9, IL-10, GM-CSF, IP-10, MIP-1b, TNF-α and VEGF levels were found in severe cases, while in non-severe cases, IL-13 and TNF-α levels were significantly higher (p < 0.05). In all groups, IP-10 was increased and RANTES was decreased. Significant and time- (after onset of illness) dependent differences among fatal, severe and non-severe cases were seen. VEGF was positively associated with disease severity. A strong immune response was seen during the first week of illness, especially in severe cases, while the response in non-severe cases was weaker and delayed. The Th1 response was strong in non-severe cases and weak in the fatal case, while a mixed Th1/Th2 immune response was seen in the survivors of severe disease.

Phlebovirus infections in Greece.

Sandfly fever viruses are endemic in the Mediterranean region causing to humans asymptomatic or mild infections to severe neurological syndromes. In order to investigate the epidemiology of phlebovirus infections in Greece, samples from 499 patients with acute febrile illness (50.2% accompanied by neurological symptoms) were tested during 2010-2014 by serological and molecular methods. Phlebovirus infection was detected in 40 (8%) patients, 25 of them presenting acute neurological infection. Most cases were observed in the summer, with a peak in August. Increased number of cases was observed in 2013, and three of them were observed in Athens. Toscana virus lineage C RNA was detected in one encephalitis case, while the serological results showed that most cases were caused by phleboviruses belonging to the sandfly fever Naples virus serocomplex. This study provided the first insight into the epidemiology of phleboviral disease in Greece.

Crimean-Congo hemorrhagic fever: CXCL10 correlates with the viral load.

Crimean-Congo hemorrhagic fever (CCHF) is a human disease with high fatality rate. Although its pathogenesis is not elucidated yet, it is considered that cytokines play a significant role in the progression and outcome of the disease. Serum CXCL10 levels were estimated in 35 patients with acute CCHF and were correlated with the viral load, and various demographic and clinical parameters. The mean CXCL10 concentration in the patients' group was higher compared to the respective value in the control group (4421.74 pg/ml vs. 28.47 pg/ml, P < 0.05). A strong positive correlation between CXCL10 and viral load was seen (rs = 0.57, P < 0.001), while the outcome of the disease was related with the viral load (rs = 0.47, P = 0.004) and the presence of hemorrhagic manifestations (P < 0.001). The study provides an insight into the strong correlation between CXCL10 and viral load in acute CCHF cases suggesting that it plays an important role in CCHF pathogenesis.

Neuroinvasive phlebovirus infection in Greece: a case report.

OBJECTIVE: Sandfly fever phleboviruses are endemic in Mediterranean countries. We report a febrile phlebovirus case in a Greek patient who presented signs of neuroinvasive infection. METHODS: In summer 2010, a 20-year-old male was admitted to hospital with fever and lethargy; he was a resident of central Macedonia, northern Greece, where a large outbreak of West Nile virus (WNV) infections occurred at that time. Since there was no laboratory evidence of WNV infection, the patient's serum and cerebrospinal fluid were tested for a probable phlebovirus infection. RESULTS: High titers of IgM and IgG antibodies against Toscana virus were detected in serum and cerebrospinal fluid, while the titers against sandfly fever Naples virus were lower; no reactivity was detected against sandfly Sicilian and Cyprus viruses. Since neutralization assays were not performed and PCR resulted in being negative, it was concluded that the causative agent was a phlebovirus of the sandfly fever Naples serocomplex. CONCLUSION: The present case confirms results from previous seroprevalence studies showing that phleboviruses of the sandfly fever Naples serocomplex are present in Greece and provides evidence that they cause febrile neuroinvasive disease in humans, prompting for inclusion of phleboviral infections in the differential diagnosis of acute febrile cases during the time when sandflies are active.

Pan-Genome Plasticity and Virulence Factors: A Natural Treasure Trove for Acinetobacter baumannii.

Acinetobacter baumannii is a Gram-negative pathogen responsible for a variety of community- and hospital-acquired infections. It is recognized as a life-threatening pathogen among hospitalized individuals and, in particular, immunocompromised patients in many countries. A. baumannii, as a member of the ESKAPE group, encompasses high genomic plasticity and simultaneously is predisposed to receive and exchange the mobile genetic elements (MGEs) through horizontal genetic transfer (HGT). Indeed, A. baumannii is a treasure trove that contains a high number of virulence factors. In accordance with these unique pathogenic characteristics of A. baumannii, the authors aim to discuss the natural treasure trove of pan-genome and virulence factors pertaining to this bacterial monster and try to highlight the reasons why this bacterium is a great concern in the global public health system.

Clostridioides difficile infection epidemiology during the COVID-19 pandemic in Greece.

Aim: The aim was to highlight the incidence and epidemiology of C. difficile infections (CDI) in a tertiary Greek hospital during the COVID-19 pandemic. Methods: A single-center prospective observational cohort study was conducted (October 2021 until April 2022). 125 C. difficile isolates were cultured from hospitalized patients stool samples and screened by PCR for toxin A (tcdA), toxin B (tcdB), binary toxin (cdtA and cdtB) genes and the regulating gene of tcdC. Results: The incidence of CDI increased to 13.1 infections per 10,000 bed days. The most common PCR ribotypes identified included hypervirulent RT027-related RT181 (73.6%), presumably hypervirulent RT126 (8.0%) and toxin A negative RT017 (7.2%). Conclusion: Although the incidence of CDI increased significantly, the CDI epidemiology remained stable.

[Box: see text].

Carbapenem-Resistant Klebsiella pneumoniae: Virulence Factors, Molecular Epidemiology and Latest Updates in Treatment Options.

Klebsiella pneumoniae is a Gram-negative opportunistic pathogen responsible for a variety of community and hospital infections. Infections caused by carbapenem-resistant K. pneumoniae (CRKP) constitute a major threat for public health and are strongly associated with high rates of mortality, especially in immunocompromised and critically ill patients. Adhesive fimbriae, capsule, lipopolysaccharide (LPS), and siderophores or iron carriers constitute the main virulence factors which contribute to the pathogenicity of K. pneumoniae. Colistin and tigecycline constitute some of the last resorts for the treatment of CRKP infections. Carbapenemase production, especially K. pneumoniae carbapenemase (KPC) and metallo-ß-lactamase (MBL), constitutes the basic molecular mechanism of CRKP emergence. Knowledge of the mechanism of CRKP appearance is crucial, as it can determine the selection of the most suitable antimicrobial agent among those most recently launched. Plazomicin, eravacycline, cefiderocol, temocillin, ceftolozane-tazobactam, imipenem-cilastatin/relebactam, meropenem-vaborbactam, ceftazidime-avibactam and aztreonam-avibactam constitute potent alternatives for treating CRKP infections. The aim of the current review is to highlight the virulence factors and molecular pathogenesis of CRKP and provide recent updates on the molecular epidemiology and antimicrobial treatment options.

Efficacy of antimicrobials or placebo compared to amoxicillin-clavulanate in children with acute otitis media: a systematic review.

BACKGROUND: Acute otitis media (AOM) is the inflammation of the middle ear. It constitutes one of the most frequent infections which affects children and usually occurs between 6 to 24 months of age. AOM can emerge due to viruses and/or bacteria. The aim of the current systematic review is to assess in children between 6 months and 12 years of age with AOM, the efficacy of any antimicrobial agent or placebo compared with amoxicillinclavulanate, to measure the resolution of AOM or symptoms. METHODS: The medical databases PubMed (MEDLINE) and Web of Science were used. Data extraction and analysis were performed by two independent reviewers. Eligibility criteria were set, and only randomised control trials (RCTs) were included. Critical appraisal of the eligible studies was performed. Pooled analysis was conducted using the Review Manager v. 5.4.1 software (RevMan). RESULTS: Twelve RCTs were totally included. Three (25.0%) RCTs studied the impact of azithromycin, two (16.7%) investigated the impact of cefdinir, two (16.7%) investigated placebo, three (25.0%) studied quinolones, one (8.3%) investigated cefaclor and one (8.3%) studied penicillin V, compared to amoxicillin-clavulanate. In five (41.7%) RCTs, amoxicillin-clavulanate proved to be superior to azithromycin, cefdinir, placebo, cefaclor and penicillin V, while in seven (58.3%) RCTs its efficacy was comparable with other antimicrobials or placebo. The rates of AOM relapse after treatment with amoxicillin-clavulanate were comparable to those of other antimicrobials or placebo. However, amoxicillin-clavulanate was more effective in eradicating Streptococcus pneumoniae from the culture, when compared to cefdinir. The results of the meta-analysis were not evaluated due to substantial heterogeneity between studies. CONCLUSIONS: Amoxicillin-clavulanate should be the treatment of choice for children between 6 months and 12 years of age with AOM.

Infection control measures against multidrug-resistant Gram-negative bacteria in children and neonates.

The increase in infections caused by multidrug-resistant (MDR) Gram-negative bacteria in neonatal and pediatric intensive care units over recent years is alarming. MDR Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii have constituted the main causes of the MDR Gram-negative bacteria problem. The implementation of infection control measures such as hand hygiene, cohorting of patients, contact precautions, active surveillance and environmental cleaning could diminish their spread. Recently, water safety has been identified as a major component of infection control policies. The aim of the current review is to highlight the effectiveness of these infection control measures in managing outbreaks caused by MDR Gram-negative bacteria in neonatal and pediatric intensive care units and highlight future perspectives on the topic.

Implication of COVID-19 pandemic on the incidence of Clostridioides difficile infection in a Greek tertiary hospital.

Introduction. C. difficile infection (CDI) represents an important global threat. In the COVID-19 era, the multifactorial nature of CDI has emerged.Hypothesis - Aim. The aim was to assess the impact of COVID-19 pandemic on the incidence of CDI in a Greek hospital.Methodology. A retrospective study was performed throughout a 51 month period (January 2018 to March 2022), divided into two periods: pre-pandemic (January 2018 to February 2020) and COVID-19 pandemic (March 2020 to March 2022). The effects of the pandemic compared to the pre-pandemic period on the incidence of CDI [expressed as infections per 10 000 bed days (IBD)] were studied using interrupted time-series analysis.Results. Throughout the study, there was an increase in the monthly CDI incidence from 0.00 to 11.77 IBD (P<0.001). Interrupted time-series disclosed an increase in CDI incidence during the pre-pandemic period from 0.00 to 3.36 IBD (P<0.001). During the COVID-19 pandemic period the linear trend for monthly CDI rose from 2.65 to 13.93 IBD (P<0.001). The increase rate was higher during the COVID-19 pandemic period (r2 = +0.47) compared to the pre-pandemic period (r1 = +0.16).Conclusion. A significant increase of CDI incidence was observed, with the rate of the rise being more intense during the COVID-19 pandemic.

Diagnostic assays for Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a highly contagious viral tick-borne disease with case-fatality rates as high as 50%. We describe a collaborative evaluation of the characteristics, performance, and on-site applicability of serologic and molecular assays for diagnosis of CCHF. We evaluated ELISA, immunofluorescence, quantitative reverse transcription PCR, and low-density macroarray assays for detection of CCHF virus using precharacterized archived patient serum samples. Compared with results of local, in-house methods, test sensitivities were 87.8%-93.9% for IgM serology, 80.4%-86.1% for IgG serology, and 79.6%-83.3% for genome detection. Specificity was excellent for all assays; molecular test results were influenced by patient country of origin. Our findings demonstrate that well-characterized, reliable tools are available for CCHF diagnosis and surveillance. The on-site use of such assays by health laboratories would greatly diminish the time, costs, and risks posed by the handling, packaging, and shipping of highly infectious biologic material.

Development time of IgG antibodies to West Nile virus.

Following an outbreak of West Nile virus (WNV) infections in Greece during summer/autumn 2010, a study was conducted to investigate the patterns of WNV IgG reactivity in 255 patients with respect to the day of illness and the type of clinical syndrome. IgG antibodies were detectable after a mean of 8.1 ± 4.9 and 12.6 ± 11.3 days after onset of illness in neuroinvasive and non-neuroinvasive cases, respectively (p < 0.001), suggesting that a delay in the development of WNV IgG antibodies is seen in non-neuroinvasive cases.

Genetic characterization of livestock-associated methicillin-resistant Staphylococcus aureus isolated in Greece.

The interest in livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains is increasing due to their wide distribution and transmission even in persons without previous contact with livestock, and these strains pose a public health threat. The aim of the study was the genetic characterization of the whole genome of two epidemiologically unrelated t034 LA-MRSA strains previously isolated from the nasal cavities of a goat and a farmer in Greece. Both strains were assigned to the ST398-Vc-t034 type and they were carrying a single transposon identical to Tn6133. They harbored genes conferring resistance to several antibiotics (aminoglycosides, ß-lactams, macrolides, streptogramin B, tetracycline, and trimethoprim), and genes associated with virulence (enterotoxins, γ-hemolysins, and aureolysin). The present study can serve as baseline for further LA-MRSA epidemiological and evolutionary studies in Greece, while awareness and increased surveillance are needed to avoid their spread.

Forecasting models of infections due to carbapenem-resistant Gram-negative bacteria in an intensive care unit in an endemic area.

OBJECTIVES: The aim of this study was to forecast the monthly incidence rates of infections [infections/1000 bed-days (IBD)] due to carbapenem-resistant Klebsiella pneumoniae (CRKP), carbapenem-resistant Pseudomonas aeruginosa (CRPA), carbapenem-resistant Acinetobacter baumannii (CRAB) and total carbapenem-resistant Gram-negative bacteria (CRGNB) in an endemic intensive care unit (ICU) during the subsequent year (December 2016-December 2017) following the observational period. METHODS: A 52-month observational period (August 2012-November 2016) was used. Two forecasting models, including a simple seasonal model for CRGNB, CRKP and CRPA and Winters' additive model for CRAB infections, were applied. RESULTS: The models predicted the highest infection rates for CRKP, CRAB and CRGNB in January and September 2017 (23.8/23.4, 24.6/28.5 and 46.8/46.7 IBD, respectively) and for CRPA in February and March 2017 (8.3 and 7.9, respectively). The highest observed rates for CRKP, CRAB and CRGNB were indeed in January and September 2017 (25.6/19.0, 34.2/23.8 and 59.8/42.8 IBD, respectively); and for CRPA in February and March of the same year (15.2 and 12.7, respectively). The increased rates may be associated with personnel's annual work programme and behavioural factors. CONCLUSION: Forecasting models in endemic ICUs may assist in implementation strategies for infection control measures.