Isolation and Characterisation of Human-Derived blaKPC-3-Producing Salmonella enterica Serovar Rissen in 2018.

In this study, we describe a Salmonella enterica serovar (S.) Rissen strain with a reduced susceptibility to meropenem, isolated from a urinary infection in an 89-year-old woman in 2018 during activity surveillance in Italy (Enter-Net Italia). The genomic characteristics, pathogenicity, and antimicrobial resistance mechanisms were investigated via a genomic approach. Antimicrobial susceptibility testing revealed a "susceptible, increased exposure" phenotype to meropenem in the S. Rissen strain (4_29_19). Whole-genome sequencing (WGS) was performed using both the NovaSeq 6000 S4 PE150 XP platform (Illumina, San Diego, CA, USA) and MinION (Oxford Nanopore). The S. Rissen 4_29_19 strain harboured two plasmids: a pKpQIL-like plasmid carrying the blaKPC-3 resistance gene in a Tn4401a transposon (pKPC_4_29_19), and a ColE-like plasmid (p4_4_29_19) without resistance genes, highly prevalent among Enterobacterales. Comparative analysis revealed that the pKPC_4_29_19 plasmid was highly related to the pKpQIL reference plasmid (GU595196), with 57% coverage and 99.96% identity, but lacking a region of about 30 kb, involving the FIIK2 replicon region and the entire transfer locus, causing the loss of its ability to conjugate. To our knowledge, this is the first time that a pKpQIL-like plasmid, carrying blaKPC-3, highly diffused in Klebsiella pneumoniae strains, has been identified in a Salmonella strain in our country. The acquisition of blaKPC genes by Salmonella spp. is extremely rare, and is reported only sporadically. In zoonotic bacteria isolated from humans, the presence of a carbapenem resistance gene carried by mobile genetic elements, usually described in healthcare-associated infection bacteria, represents an important concern for public health.

Antibiotic resistance, plasmids, and virulence-associated markers in human strains of Campylobacter jejuni and Campylobacter coli isolated in Italy.

Campylobacteriosis, a prevalent foodborne gastrointestinal infection in Europe, is primarily caused by Campylobacter jejuni and Campylobacter coli, with rising global concerns over antimicrobial resistance in these species. This study comprehensively investigates 133 human-origin Campylobacter spp. strains (102 C. jejuni and 31 C. coli) collected in Italy from 2013 to 2021. The predominant Multilocus Sequence Typing Clonal complexes (CCs) were ST-21 CC and ST-206 CC in C. jejuni and ST-828 CC in C. coli. Ciprofloxacin and tetracycline resistance, mainly attributed to GyrA (T86I) mutation and tet(O) presence, were prevalent, while erythromycin resistance was associated with 23S rRNA gene mutation (A2075G), particularly in C. coli exhibiting multidrug-resistant pattern CipTE. Notable disparities in virulence factors among strains were observed, with C. jejuni exhibiting a higher abundance compared to C. coli. Notably, specific C. jejuni sequence types, including ST-21, ST-5018, and ST-1263, demonstrated significantly elevated counts of virulence genes. This finding underscores the significance of considering both the species and strain-level variations in virulence factor profiles, shedding light on potential differences in the pathogenicity and clinical outcomes associated with distinct C. jejuni lineages. Campylobacter spp. plasmids were classified into three groups comprising pVir-like and pTet-like plasmids families, exhibiting diversity among Campylobacter spp. The study underscores the importance of early detection through Whole Genome Sequencing to identify potential emergent virulence, resistance/virulence plasmids, and new antimicrobial resistance markers. This approach provides actionable public health data, supporting the development of robust surveillance programs in Italy.

Colistin Resistance Mechanisms in Human Salmonella enterica Strains Isolated by the National Surveillance Enter-Net Italia (2016-2018).

BACKGROUND: A collection of human-epidemiologically unrelated S. enterica strains collected over a 3-year period (2016 to 2018) in Italy by the national surveillance Enter-Net Italia was analysed. METHODS: Antimicrobial susceptibility tests, including the determination of minimal inhibitory concentrations (MICs) for colistin, were performed. Colistin resistant strains were analysed by PCR to detect mobile colistin resistance (mcr) genes. In mcr-negative S. enterica serovar Enteritidis strains, chromosomal mutations potentially involved in colistin resistance were identified by a genomic approach. RESULTS: The prevalence of colistin-resistant S. enterica strains was 7.7%, the majority (87.5%) were S. Enteritidis. mcr genes were identified only in one strain, a S. Typhimurium monophasic variant, positive for both mcr-1.1 and mcr-5.1 genes in an IncHI2 ST4 plasmid. Several chromosomal mutations were identified in the colistin-resistant mcr-negative S. Enteritidis strains in proteins involved in lipopolysaccharide and outer membrane synthesis and modification (RfbN, LolB, ZraR) and in a component of a multidrug efflux pump (MdsC). These mutated proteins were defined as possible candidates for colistin resistance in mcr-negative S. Enteritidis of our collection. CONCLUSIONS: The colistin national surveillance in Salmonella spp. in humans, implemented with genomic-based surveillance, permitted to monitor colistin resistance, determining the prevalence of mcr determinants and the study of new candidate mechanisms for colistin resistance.

Human Campylobacteriosis in Italy: Emergence of Multi-Drug Resistance to Ciprofloxacin, Tetracycline, and Erythromycin.

Campylobacter spp. is one of the main cause of bacterial gastroenteritis in the world. The increase of antibiotic resistance in this species is a threat to public health. A Campylobacter spp. surveillance study was performed in Italy in the 2013-2016 period by the Enter-Net Italia network. The most prevalent Campylobacter species identified causing gastroenteritis was Campylobacter jejuni (73.4%) and 45% of all the annual cases of campylobacteriosis were reported in the summer period. High rates of ciprofloxacin and tetracycline resistance in Campylobacter spp. have been observed. An increasing percentage of Campylobacter coli strains simultaneously resistant to ciprofloxacin, tetracycline and erythromycin has been found. Molecular mechanisms of resistance have been investigated and the role of efflux pumps evaluated. Antibiotic resistance in Campylobacter spp. is an increasing serious threat that requires coordinated action to minimize the emergence and spread of antimicrobial resistant strains from animals to humans throughout the food chain.

[Non-tubercular vertebral osteomyelitis: diagnosis and therapy of 45 patients from a single Italian centre]. / Spondilodisciti non tubercolari: valutazione prospettica di 45 pazienti seguiti presso un unico.

AIM OF THE STUDY: to evaluate the episodes of non-tubercular spondylodiskitis diagnosed between 1998 and 2002 at the Ospedale S. Corona, Pietra Ligure (SV). METHODS: perspective evaluation of vertebral osteomyelitis classified as spontaneous or iatrogenic if associated with procedures on the spinal cord, with detection of associated risk factors, localization, aetiology and treatment. RESULTS: 45 episodes, 71% spontaneous and 29% iatrogenic were observed. Associated risk factors were present in 47% of spontaneous spondylodiskitis. Lumbosacral localization was detected in 68% of spontaneous and 100% of iatrogenic episodes. Other localizations in spontaneous spondylodiskitis were dorsal (25%) or cervical (7%). Methicillin-sensitive staphylococci caused the majority of spontaneous spondylodiskitis, while methicillin-resistant strains were more frequently involved in iatrogenic episodes. Among spontaneous spondylodiskitis, 63% healed with antibiotics for 8 weeks, but surgery was often needed in dorsal localizations. In iatrogenic forms antibacterial therapy for 8 weeks-6 months was effective in cases not associated with foreign bodies but their presence always required surgery for healing. CONCLUSIONS: spondylodiskitis is more frequently localized at lumbosacral level. Beta-lactams are generally effective in spontaneous episodes, while iatrogenic ones often require associations of drugs. Surgery may be required in the case of dorsal localization or in the presence of foreign bodies.

[Non-tubercular vertebral osteomyelitis: diagnosis and therapy of 45 patients from a single Italian centre]. / Non-tubercular vertebral osteomyelitis: diagnosis and therapy of 45 patients from a single Italian centre.

AIM OF THE STUDY: to evaluate the episodes of non-tubercular spondylodiskitis diagnosed between 1998 and 2002 at Ospedale S. Corona, Pietra Ligure (SV). METHODS: prospective evaluation of vertebral osteomyelitis classified as spontaneous or iatrogenic if associated with procedures on the spinal cord, with detection of associated risk factors, localization, etiology and treatment. RESULTS: 45 episodes, 71% spontaneous and 29% iatrogenic were observed. Associated risk factors were present in 47% of spontaneous spondylodiskitis. Lumbosacral localization was detected in 68% of spontaneous and 100% of iatrogenic episodes. Other localizations in spontaneous spondylodiskitis were dorsal (25%) or cervical (7%). Methicillin-sensitive staphylococci caused the majority of spontaneous spondylodiskitis, while methicillin-resistant strains were more frequently involved in iatrogenic episodes. Among spontaneous spondylodiskitis, 63% healed with antibiotics for 8 weeks, but surgery was often needed in dorsal localizations. In iatrogenic forms antibacterial therapy for 8 weeks-6 months was effective in cases not associated with foreign bodies but their presence always required surgery for healing. CONCLUSIONS: spondylodiskitis is more frequently localized at the lumbosacral level. Beta-lactams are generally effective in spontaneous episodes, while iatrogenic episodes often require associations of drugs. Surgery may be required in the case of dorsal localization or in the presence of foreign bodies.