Matrix-assisted laser desorption ionization-time of flight and comparative genomic analysis of M-18 group a Streptococcus strains associated with an acute rheumatic fever outbreak in northeast Italy in 2012 and 2013.

Acute rheumatic fever (ARF) is a postsuppurative sequela caused by Streptococcus pyogenes infections affecting school-age children. We describe here the occurrence of an ARF outbreak that occurred in Bologna province, northeastern Italy, between November 2012 and May 2013. Molecular analysis revealed that ARF-related group A Streptococcus (GAS) strains belonged to the M-18 serotype, including subtypes emm18.29 and emm18.32. All M-18 GAS strains shared the same antigenic profile, including SpeA, SpeB, SpeC, SpeL, SpeM, and SmeZ. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis revealed that M-18 GAS strains grouped separately from other serotypes, suggesting a different S. pyogenes lineage. Single nucleotide polymorphisms and phylogenetic analysis based on whole-genome sequencing showed that emm18.29 and emm18.32 GAS strains clustered in two distinct groups, highlighting genetic variations between these subtypes. Comparative analysis revealed a similar genome architecture between emm18.29 and emm18.32 strains that differed from noninvasive emm18.0 strains. The major sources of differences between M-18 genomes were attributable to the prophage elements. Prophage regions contained several virulence factors that could have contributed to the pathogenic potential of emm18.29 and emm18.32 strains. Notably, phage ΦSPBO.1 carried erythrogenic toxin A gene (speA1) in six ARF-related M-18 GAS strains but not in emm18.0 strains. In addition, a phage-encoded hyaluronidase gene (hylP.2) presented different variants among M-18 GAS strains by showing internal deletions located in the α-helical and TSßH regions. In conclusion, our study yielded insights into the genome structure of M-18 GAS strains responsible for the ARF outbreak in Italy, thus expanding our knowledge of this serotype.

Use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to detect carbapenemase production in Enterobacteriaceae by a rapid meropenem degradation assay.

We evaluated the analytical performance of a liquid chromatography-tandem mass spectrometry assay to detect carbapenemase activity in a group of carbapenemase-producing Enterobacteriaceae by meropenem hydrolysis. This one-hour method showed a sensitivity of 94% and a specificity of 100%, representing a rapid and reliable option compared to conventional phenotypic assays.

Evaluation of Biofilm Production and Antifungal Susceptibility to Fluconazole in Clinical Isolates of Candida spp. in Both Planktonic and Biofilm Form.

Candida spp. are an important opportunistic pathogen that can represent a possible cause of severe infections, especially in immunocompromised individuals. The clinical impact of Candida spp. depends, in part, on the ability to form biofilms, communities of nestled cells into the extracellular matrix. In this study, we compared the biofilm formation ability of 83 strains of Candida spp. isolated from blood cultures and other materials, such as respiratory samples, urine, and exudate, and their sensitivity to fluconazole (FLZ). Strains were divided into tertiles to establish cut-offs to classify isolates as low, moderate, or high biofilm producers (<0.26, 0.266-0.839, >0.839) and biofilms with low, moderate, or high metabolic activity (<0.053, 0.053-0.183, >0.183). A non-linear relationship between biofilm production and metabolic activity was found in C. glabrata and C. tropicalis. In addition, the increase in minimum biofilm eradication concentrations (MBEC50) compared to the Minor Inhibitory Concentration (PMIC) of the planktonic form in Candida spp. confirms the role of biofilm in the induction of resistance to FLZ.

Descending necrotizing mediastinitis caused by retro-pharyngeal Eggerthia catenaformis infection.

Introduction: Eggerthia catenaformis, a non-spore-forming anaerobic Gram-positive bacillus component of the human fecal microbiota has rarely been reported in human diseases. In almost every case described in current literature to date, dental diseases (abscesses, periodontitis, or caries), are the most common source of the infection which extends to the brain, cervical spaces, pulmonary parenchyma, the pleural cavity, the abdominal wall, and the abdominal cavity. Case report: An 82-year-old male Caucasian patient was admitted to our Emergency Department (ED) with a painless, right submandibular mass, dyspnea, and inspiratory stridor. A CT scan of the head, neck, and chest with intravenous contrast material revealed a retrotonsillar fluid collection. Air bubbles and minimal fluid were present from the right sub-mandibular area to the lower mediastinum between the spine, the descending thoracic aorta, and the trachea. The patient underwent surgical treatment and a broad-spectrum antibiotic. The retropharyngeal fluid collection culture showed the presence of Eggerthia catenaformis. After a first period in the Intensive Care Unit, he was admitted to a Step-Down Unit (SDU) where he underwent respiratory weaning, motor rehabilitation, and gradual oral feeding resumption. At discharge, the patient maintained the tracheal cannula as he still had impaired swallowing of solid foods. Conclusions: Here we report the first case of descending necrotizing mediastinitis in a patient with a retropharyngeal abscess, in the absence of dental diseases.

Evaluation of phenotypic and genotypic approaches for the detection of class A and class B carbapenemases in Enterobacteriaceae.

The spread of carbapenemases in Enterobacteriaceae is among the most important issues in the antimicrobial resistance. The rapid and recent diffusion of class A and B carbapenemases determined the need of specific diagnostic tests able to detect with high sensitivity this type of resistance and to discriminate between the different enzymes. The aim of this study was to test two carbapenemase detection assays, the Rosco Synergic and the Hyplex polymerase chain reaction-enzyme-linked immunosorbent assays for screening carbapenemase-producing Enterobacteriaceae. The phenotypic and genotypic tests were evaluated among 108 clinical isolates, including Klebsiella pneumoniae carbapenemase (KPC) (n=50) and metallo-ß-lactamase- (MBL) (n=20), and AmpC- (n=10) producing Enterobacteriaceae. The commercial phenotypic assay showed a high sensitivity performance detecting all KPC and MBL producers, including New Delhi MBL 1 (NDM-1) strains. In addition, the Rosco Synergic assay was able to distinguish specifically between the different mechanisms that confer resistance to carbapenems in Enterobacteriaceae. We also demonstrated that the genotypic test was able to detect all the class A and B carbapenemases showing high sensitivity (100%) and specificity (98%) in a fast and reliable time. Based on these results, both the commercial phenotypic and the genotypic assays could be helpful as confirmatory and discriminatory tests for the detection of class A and class B carbapenemases.

Outbreak of Citrobacter freundii carrying VIM-1 in an Italian Hospital, identified during the carbapenemases screening actions, June 2012.

OBJECTIVE: The identification of patients colonized or infected with carbapenemase-producing Enterobacteriaceae (CPE), in order to control and prevent the global spread of multidrug-resistant (MDR) pathogens. METHODS: From June 1 to June 15, 2012, eight Citrobacter freundii strains with reduced susceptibility to carbapenems were isolated from rectal swabs of hospitalized patients during active screening following the detection of a Klebsiella pneumoniae carbapenemase (KPC) -positive patient on the ward. All isolates were analyzed phenotypically and molecularly by PCR and sequencing. Genotype clustering was performed by multilocus sequence typing (MLST) analysis. RESULTS: The isolates showed high rates of multidrug resistance profile. A phenotypic assay for carbapenemase production suggested the presence of metallo-ß-lactamase (MBL). The blaVIM-1 gene was detected in all imipenem-resistant C. freundii isolates. MLST showed that the C. freundii isolates shared the same sequence type (ST). Phylogenetic analysis revealed a strict relationship with an ST5C. freundii isolate from a diarrhea patient in China. CONCLUSIONS: Our findings showed that the active surveillance program for CPE was useful, not only for the detection of KPC-producers, but also to identify and control the spread of other MDR pathogens that could expand the spectrum of circulating MDR pathogens.