High-Risk Clone of Klebsiella pneumoniae Co-Harbouring Class A and D Carbapenemases in Italy.

Background: Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) is endemic globally, causing severe infections in hospitalized patients. Surveillance programs help monitor and promptly identify the emergence of new clones. We reported the rapid spread of a novel clone of K. pneumoniae co-harbouring class A and D carbapenemases in colonized patients, and the potential risk factors involved in the development of infections. Methods: Rectal swabs were used for microbiological analyses and detection of the most common carbapenemase encoding genes by real-time PCR (i.e., blaKPC, blaOXA-48, blaNDM, blaVIM, and blaIMP). All strains co-harbouring KPC and OXA-48 genes were evaluated. For each patient, the following variables were collected: age, sex, length and ward of stay, device use, and outcome. Clonality of CR-Kp was assessed by preliminary pulsed field gel electrophoresis (PFGE), followed by multi-locus sequence typing (MLST) analyses. Results: A total of 127 isolates of K. pneumoniae co-harbouring KPC and OXA-48 were collected between September 2019 and December 2020. The median age (IQR) of patients was 70 (61-77). More than 40% of patients were admitted to intensive care unit (ICU). Around 25% of patients developed an invasive infection, the majority of which were respiratory tract infections (17/31; 54.8%). ICU stay and invasive infection increased the risk of mortality (OR: 5.39, 95% CI: 2.42-12.00; OR 6.12, 95% CI: 2.55-14.69, respectively; p-value ≤ 0.001). The antibiotic susceptibility test showed a resistance profile for almost all antibiotics considered. Monoclonal origin was confirmed by PFGE and MLST showing a similar restriction pattern and belonging to ST-512. Conclusions: We report the spread and the marked antibiotic resistance profiles of K. pneumoniae strains co-producing KPC and OXA-48. Further study could clarify the roles of clinical and microbiological variables in the development of invasive infection and increasing risk of mortality, in colonized patients.

Genomic Characterization of KPC-31 and OXA-181 Klebsiella pneumoniae Resistant to New Generation of ß-Lactam/ß-Lactamase Inhibitor Combinations.

BACKGROUND: Carbapenem resistant Klebsiella pneumoniae (cr-Kp) causes serious infections associated with a high mortality rate. The clinical efficacy of ceftazidime/avibactam (CZA), meropenem/vaborbactam (M/V), and imipenem/relebactam (I/R) against cr-Kp is challenged by the emergence of resistant strains, making the investigation and monitoring of the main resistance mechanisms crucial. In this study, we reported the genome characterization of a Klebsiella pneumoniae strain isolated from a critically ill patient and characterized by a multidrug resistant (MDR) profile, including resistance to CZA, M/V, and I/R. METHODS: An antimicrobial susceptibility test (AST) was performed by an automated system and E-test and results were interpreted following the EUCAST guidelines. Genomic DNA was extracted using a genomic DNA extraction kit and it was sequenced using the Illumina Nova Seq 6000 platform. Final assembly was manually curated and carefully verified for detection of antimicrobial resistance genes, porins modifications, and virulence factors. RESULTS: The K. pneumoniae isolate belonged to sequence type ST512 and harbored 23 resistance genes, conferring resistance to all antibiotic classes, including blaKPC-31 and blaOXA-181, leading to carbapenems resistance. The truncation of OmpK35 and mutation OmpK36GD were also observed. CONCLUSIONS: The genomic characterization demonstrated the high resistant profile of new cr-Kp coharboring class A and D carbapenemases. The presence of KPC-31, as well as the detection of OXA-181 and porin modifications, further limit the therapeutic options, including the novel combinations of ß-lactam/ß-lactamase inhibitor antibiotics in patients with severe pneumonia caused by cr-Kp.

Travel-Related Typhoid Fever: Narrative Review of the Scientific Literature.

Enteric fever is a foodborne infectious disease caused by Salmonella enterica serotypes Typhi and Paratyphi A, B and C. The high incidence in low income countries can increase the risk of disease in travelers coming from high income countries. Pre-travel health advice on hygiene and sanitation practices and vaccines can significantly reduce the risk of acquiring infections. Although the majority of the cases are self-limiting, life-threatening complications can occur. Delayed diagnosis and cases of infections caused by multi-drug resistant strains can complicate the clinical management and affect the prognosis. More international efforts are needed to reduce the burden of disease in low income countries, indirectly reducing the risk of travelers in endemic settings. Surveillance activities can help monitor the epidemiology of cases caused by drug-susceptible and resistant strains.

Resistance to linezolid in Staphylococcus spp. clinical isolates associated with ribosomal binding site modifications: novel mutation in domain V of 23S rRNA.

Linezolid is the main representative of the oxazolidinones, introduced in 2000 in clinical practice to treat severe Gram-positive infections. This compound inhibits protein synthesis by binding to the peptidyl transferase centre of the 50S bacterial ribosomal subunit. The aim of this study was to characterize 12 clinical strains of linezolid-resistant Staphylococcus spp. isolated in Northern Italy. All isolates of Staphylococcus spp. studied showed a multi-antibiotic resistance phenotype. In particular, all isolates showed the presence of the mecA gene associated with SSCmec types IVa, V or I. Mutations in domain V of 23S rRNA were shown to be the most prevalent mechanism of linezolid resistance: among these a new C2551T mutation was found in S. aureus, whilst the G2576T mutation was shown to be the most prevalent overall. Moreover, three S. epidermidis isolates were shown to have linezolid resistance associated only with alterations in both L3 and L4 ribosomal proteins. No strain was shown to harbor the previously described cfr gene. These results have shown how the clinical use of linezolid in Northern Italy has resulted in the selection of multiple antibiotic-resistant clinical isolates of Staphylococcus spp., with linezolid resistance in these strains being associated with mutations in 23S rRNA or ribosomal proteins L3 and L4.

[Microbial contamination of surfaces in the departments of Medicine and Surgery: single center prevalence study in Sassari (Italy)]. / Contaminazioni microbiche di superfici di frequente contatto in reparti di medicina e chirurgia: studio monocentrico di prevalenza a Sassari.

INTRODUCTION: Healthcare-associated infections (HAIs) represent a clinical and public health problem worldwide. Microbial transmission can frequently occurs between patients or between patients and health-care workers; however, several devices and surfaces could act as reservoir and source of microorganisms. Aim of this cross-sectional study was to show the microbial contamination of devices or surfaces located in the departments of Medicine and Surgery of an Italian University Hospital. METHODS: Swabs were used to sample devices (keyboards, phones) and surfaces (door handles, water closed, light switches), at two different time-points. Samples were then evaluated in the UOC Hygiene and Preventive Medicine laboratory of the same University Hospital. RESULTS: 189 swabs were collected, 95 (53.3%) from the Medicine and 94 (49.7%) from the Surgery Department. The bacterial contamination prevalence was 42.9%, significantly higher in the Medicine than in the Surgery Department (51.6% vs 34%; p=0.015). A greater contamination was observed in water closed (22/36, 61.1%), phones (22/40, 55%), and keyboards of personal computers (18/36, 51.4%; p<0.001). No statistical differences were detected in the contamination rates when the different time-points were compared, as well as in the isolation rate of pathogenic bacterial strains. DISCUSSION: This survey highlights the potential role of devices and surfaces in the HAI pathogenesis. Further longitudinal and analytical studies might better assess the HAI risk associated with bacterial contamination in nosocomial settings.

Molecular typing of XDR Acinetobacter baumannii strains in an Italian ICU.

OBJECTIVE: To investigate the antimicrobial susceptibility and clonal relationship of Acinetobacter baumannii strains isolated in an Italian ICU. DESIGN: Epidemiological, observational, retrospective, longitudinal study. SETTING AND PARTICIPANTS: The ICU of the University Hospital of Sassari, Italy. MAIN OUTCOME MEASURES: Pulsed Field Gel Electrophoresis (PFGE) and Multi Locus Sequence Typing (MLST) were used to evaluate the genomic features of the isolated strains. RESULTS: Drug susceptibility testing for all isolated strains showed the same resistance pattern, characterized by resistance to the most important antibiotics, with the only exception of colistin. PFGE showed a very poor between-strain variability; three distinct clusters, 11, 4, and 1 isolates in size, were identified (Dice's coefficient: 92.11%). MLST showed that all isolated strains belonged to sequence type 2 (ST2). All isolates collected from the environment and the human samples were positive for the following genes: blaOXA-23, blaOXA-51-like, blaVIM-like, blaIMP-like, andISAba1; however, blaOXA-24-like, blaOXA-58-like, and blaNDM-like were not detected. CONCLUSIONS: The survey identified XDR strains belonging to the same cell clone, confirming the wide circulation and environmental persistence of this microorganism.

[In vitro evaluation of antimicrobial activity of absorbable topical hemostatic agents used in the operating room]. / Valutazione in vitro dell'attività antimicrobica di dispositivi medici emostatici in uso in chirurgia.

The aim of this study was to evaluate the antimicrobial activity of three absorbable, sterile, regenerated oxidized cellulose gauzes against ATCC and clinical isolates of bacterial and fungal strains, in particular those most frequently involved in surgical site infections. The three cellulose devices showed rapid antimicrobial activity against the microbial species tested. Their use could be a valuable adjunct to antibiotic prophylaxis in the prevention of surgical site infections.

[Evolution of the molecular characterization profile of salmonellosis: the experience of Sardinia, Italy, 1994-2009]. / Evoluzione del panorama epidemiologico delle salmonellosi. Esperienze di monitoraggio in Sardegna.

The epidemiology of salmonellosis in Italy has clearly changed over the years. The circulation of human-specific genotypes has diminished while there has been an increase in genotypes of animal origin. In the years 1994-2009, 3727 Salmonella genotypes were isolated and/or genotyped in Sardinia (Italy). The most frequent serotypes were Salmonella Enteritidis (29%) and Salmonella Typhimurium (25,7%). If we consider the years 2000-2009, 6.4% of isolated genotypes were found to be Salmonellae with the serologic profile 4,5,12:i:-, 35.8% of which were multiresistant. Molecular analyses have shown a correlation between Salmonellae 4,5,12:i:- and Salmonellae Typhimurium DT104. Further studies will be conducted to evaluate the link with other Salmonella variants with a similar serologic profile.

Interplay between Helicobacter pylori and host gene polymorphisms in inducing oxidative DNA damage in the gastric mucosa.

Infection by Helicobacter pylori is the most important risk factor for gastric cancer. However, only a small fraction of colonized individuals, representing at least half of the world's population, develop this malignancy. In order to shed light on host-microbial interactions, gastric mucosa biopsies were collected from 119 patients suffering from dyspeptic symptoms. 8-Hydroxy-2'-deoxyguanosine (8-oxo-dG) levels in the gastric mucosa were increased in carriers of H.pylori, detected either by cultural method or by polymerase chain reaction, and were further increased in subjects infected with strains positive for the cagA gene, encoding the cytotoxin-associated protein, cagA. Oxidative DNA damage was more pronounced in males, in older subjects, and in H.pylori-positive subjects suffering from gastric dysplasia. Moreover, 8-oxo-dG levels were significantly higher in a small subset of subjects having a homozygous variant allele of the 8-oxoguanosine-glycosylase 1 (OGG1) gene, encoding the enzyme removing 8-oxo-dG from DNA. Conversely, they were not significantly elevated in glutathione S-transferase M1 (GSTM1)-null subjects. Thus, both bacterial and host gene polymorphisms affect oxidative stress and DNA damage, which is believed to represent a key mechanism in the pathogenesis of gastric cancer. The interplay between bacterial and host gene polymorphisms may explain why gastric cancer only occurs in a small fraction of H.pylori-infected individuals.

Prevalence study of Legionella spp. contamination in ferries and cruise ships.

BACKGROUND: In the last years, international traffic volume has significantly increased, raising the risk for acquisition of infectious diseases. Among travel-associated infections, increased incidence of legionellosis has been reported among travellers. Aim of our study was: to describe the frequency and severity of Legionella spp. contamination in ferries and cruise ships; to compare the levels of contamination with those indicated by the Italian ministerial guidelines for control and prevention of legionellosis, in order to assess health risks and to adopt control measures. METHOD: A prevalence study was carried out on 9 ships docked at the seaports of northern Sardinia in 2004. Water samples were collected from critical sites: passenger cabins, crew cabins, kitchens, coffee bars, rooms of the central air conditioning system. It was performed a qualitative and quantitative identification of Legionella spp. and a chemical, physical and bacteriological analysis of water samples. RESULTS: Forty-two percent (38/90) water samples were contaminated by Legionella spp.. Positive samples were mainly drawn from showers (24/44), washbasins (10/22). L. pneumophila was isolated in 42/44 samples (95.5%), followed by L. micdadei (4.5%). Strains were identified as L. pneumophila serogroup 6 (45.2%; 19 samples), 2-14 (42.9%), 5 (7.1%) and 3 (4.8%). Legionella spp. load was high; 77.8% of the water samples contained > 10(4) CFU/L. Low residual free chlorine concentration (0-0.2 mg/L) was associated to a contamination of the 50% of the water samples. CONCLUSION: Legionella is an ubiquitous bacterium that could create problems for public health. We identified Legionella spp. in 6/7 ferries. Microbial load was predominantly high (> 10(4) CFU/L or ranging from 10(3) to 10(4) CFU/L). It is matter of concern when passengers are subjects at risk because of Legionella spp. is an opportunist that can survive in freshwater systems; high bacterial load might be an important variable related to disease's occurrence. High level of contamination required disinfecting measures, but does not lead to a definitive solution to the problem. Therefore, it is important to identify a person responsible for health safety in order to control the risk from exposure and to apply preventive measures, according to European and Italian guidelines.