FosA8-producing E. coli ST131: clinical cases in Italy, February 2023.

Fosfomycin-resistant FosA8-producing Enterobacterales are uncommon strains with extremely low incidence in Europe, based on only three reports in the literature. We detected FosA8-producing Escherichia coli ST131 in clinical isolates from two patients admitted in February 2023 to a rehabilitation unit in Italy. The occurrence of rare fosA-like genes in the high-risk clone ST131 is of clinical relevance. The dissemination of FosA-producing E. coli, although still at low levels, should be continuously monitored.

Unexplained Hyperthyrotropinemia: A Biochemical and Clinical Challenge.

BACKGROUND: A raised serum TSH in the absence of a clear etiology, or "unexplained hyperthyrotropinemia" (UH), can be challenging for clinicians. The aim of the present study was to evaluate potential strategies aimed at a clinical and biochemical characterization of UH patients. METHODS: We compared 36 patients with UH with a control group of 14 patients with chronic autoimmune thyroiditis (CAT) and subclinical hypothyroidism. The two groups were compared in terms of the following: (i) the rate of normalization of TSH after repeating with another assay; (ii) the rate of normalization of TSH over time with the same assay; (iii) the reduction in TSH after precipitation with polyethilenglycole (PEG); and (iv) free thyroxine (FT4) levels. RESULTS: Similar TSH levels were observed in UH [5.65 (5.21-6.37)] and CAT [5.62 (5.17-8.50)] (p = 0.489). TSH measurement with another assay method showed a normal TSH value in 41.9% of UH vs. 46.1% of CAT patients (p = 0.797). After repeating the TSH measurement in time with the same assay method, an increased TSH value was confirmed in all cases, in both groups (0% in the UH group vs. 0% in the CAT group, p = 1.000). TSH recovery after PEG precipitation was similar in the two groups (% precipitable post-PEG: 68.75 ± 3.14 in UH vs. 68.67 ± 7.18 in CAT, p = 0.960). FT4 levels were similar in the two groups (FT4 1.02 ± 0.20 ng/dl in UH vs. 1.00 ± 0.20 ng/dl in CAT, p = 0.789). CONCLUSIONS: The results do not support the concept that laboratory interferences are more frequent in UH patients, suggesting that patients with UH should be managed in the same way as patients with CAT until proven otherwise.

Pegvisomant-primed growth hormone (GH) stimulation test is useful in identifying true GH deficient children.

OBJECTIVE: Provocative stimulation tests for growth hormone (GH) assessment have poor reproducibility and can often elicit false positive results in normal children. The aim of our study was to confirm the capability of pegvisomant as an enhancer of GH secretion in unmasking false-positive results in short children (height <-2.0 standard deviation score, SDS) undergoing GH testing. DESIGN: A prospective study was conducted between March and August 2016. Twenty short children (10 males and 10 females), aged 4.6-13.4 years, previously diagnosed as GH deficient (GHD) were included in the study. All subjects received 1 mg/kg of pegvisomant subcutaneously; three days later an insulin tolerance test (ITT) was performed. Insulin-like growth factor-I (IGF-I) was evaluated before and three days after pegvisomant administration. RESULTS: After pegvisomant priming and the ITT stimulation test, 12 out of the 20 children initially classified as GHD showed a GH peak of more than 10 ng/ml and were thus reclassified as short normal. Furthermore, a significant reduction of IGF-I was observed in the GHD group (pre IGF-I: median (IQR) 144.0 (109-248) ng/ml, post IGF-I: 98 (49-165) ng/ml; p<0.001) after pegvisomant administration. CONCLUSIONS: Pegvisomant priming before GH stimulation tests can be used to improve the reliability of the diagnostic work-up in GH deficiency.

Detection of an IncA/C plasmid encoding VIM-4 and CMY-4 ß-lactamases in Klebsiella oxytoca and Citrobacter koseri from an inpatient in a cardiac rehabilitation unit.

A 62-year-old patient was transferred to the cardiac rehabilitation unit of the I.R.C.C.S. Fondazione S. Maugeri after undergoing a heart transplantation at the Acute Care Hospital I.R.C.C.S. S. Matteo of Pavia. On 1 August 2013 and during hospitalization in the rehabilitation unit, Klebsiella oxytoca and Citrobacter koseri clinical isolates were simultaneously recovered from the patient's preputial swab. Both the K. oxytoca and C. koseri strains were carbapenem- resistant by MicroScan System (Beckman Coulter). Carbapenem-resistant K. pneumoniae had previously been reported in the same rehabilitation facility. The aim of the study was to identify the carbapenem resistance mechanisms among the enterobacterial species recovered. Phenotypic screening tests useful to detect the ß-lactamases/carbapenemases were performed. Carbapenem MICs were obtained by Etest. AmpC and MBL encoding genes were identified by PCR and sequencing. Conjugation assays and plasmid characterization were performed. Both of the K. oxytoca and C. koseri isolates were multi drug resistant, showing resistance to amoxicillin-clavulanic acid, three generation cephalosporins, ertapenem (K. oxytoca MIC, >32 mg/L; C. koseri MIC, 4 mg/L), imipenem (K. oxytoca MIC, 4 mg/L; C. koseri MIC, 12 mg/L), thrimethoprim sulphamethoxazole and gentamicin. Susceptibility was retained to fluoroquinolones, colistin and tigecycline. Molecular characterization confirmed the co-presence of blaCMY-4 and blaVIM-4 determinants in a 150 Kb transferable plasmid of IncA/C group. This case is the first detection in Italy of the K. oxytoca and C. koseri clinical isolates co-producing the CMY-4 and VIM-4 enzymes.

Emergence of a VIM-1 MBL and CTX-M-15 ESbL-producing Klebsiella pneumoniae clone from acute and rehabilitation hospitals in Italy.

We report the emergence of VIM-1 MBL and CTX-M-15-producing K. pneumoniae isolates collected from patients at two acute care hospitals (I.R.C.C.S. "S. Matteo" and "Casa Sollievo della Sofferenza" Hospital) and a long-term rehabilitation facility in Northern Italy (I.R.C.C.S. "S. Maugeri"). Between February 2007 and October 2008, 30 K. pneumoniae strains showing decreased susceptibility to carbapenems were collected. PCR and sequencing experiments revealed the presence of blaVIM-1 gene in 14/30 isolates. All the above isolates carried the blaSHV-5 determinant as well; interestingly, 8/14 VIM positive isolates were also CTX-M-1- like producers. VIM-1 positive strains were present in all hospitals. PFGE genomic profiles of the 14/30 isolates showed that 2 different clones, A and B, were responsible for outbreaks. The coexistence in the same bacterial cell of compatible plasmids carrying epidemiologically important emerging resistance genes, such as MBLs and CTX-Ms, is worrisome since it could predict the generation and spread of pan-resistant bacteria and the consequent treatment option limitations that can lead to significant morbidity and mortality. Control measures should be applied to detect MBL-producing strains and to contrast the vertical and plasmidic diffusion of carbapenem-resistant K. pneumoniae in acute care and rehabilitation facilities.

Growth in glucose-based medium and exposure to subinhibitory concentrations of imipenem induce biofilm formation in a multidrug-resistant clinical isolate of Acinetobacter baumannii.

BACKGROUND: Acinetobacter baumannii is emerging as an important nosocomial pathogen. Multidrug resistance, as well as ability to withstand environmental stresses, makes eradication of A. baumannii difficult, particularly from hospital settings. RESULTS: Over a six-year period, 73 isolates of A. baumannii were collected from infected patients in two hospitals in Italy. While 69 out of the 73 isolates displayed identical multidrug antibiotic resistance pattern, they were susceptible to carbapenems. Genetic profiles of these 69 isolates, determined by Pulsed Field Gel Electrophoresis (PFGE), indicated that they were genetically related and could be clustered in a specific clone, called SMAL. We tested the ability of the SMAL clone to form biofilm, an important determinant for bacterial colonization of the human host and for persistence in the hospital environment. Biofilm formation by A. baumannii SMAL, measured as surface adhesion to polystyrene, is strongly affected by growth conditions, being impaired in rich growth media such as LB, while being favoured in glucose-based medium. Surface adhesion in glucose-based media is inhibited by treatment with cellulase, suggesting that it depends on production of cellulose or of a chemically related extracellular polysaccharide. Exposure of A. baumannii SMAL to subinhibitory concentrations of imipenem resulted in biofilm stimulation and increased production of iron uptake proteins. Growth in iron-supplemented medium also stimulated surface adhesion, thus suggesting that increased intracellular iron concentrations might act as an environmental signal for biofilm formation in A. baumannii SMAL. CONCLUSIONS: Our results indicate that exposure to subinhibitory concentrations of imipenem can stimulate biofilm formation and induce iron uptake in a pathogenic strain of A. baumannii, with potential implications on antibiotic susceptibility and ability to persist in the human host.