Genomic characterization of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) strains circulating in three university hospitals in Northern Italy over three years.

OBJECTIVES: Genomic surveillance of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) is crucial for virulence, drug-resistance monitoring, and outbreak containment. METHODS: Genomic analysis on 87 KPC-Kp strains isolated from 3 Northern Italy hospitals in 2019-2021 was performed by whole genome sequencing (WGS), to characterize resistome, virulome, and mobilome, and to assess potential associations with phenotype resistance and clinical presentation. Maximum Likelihood and Minimum Spanning Trees were used to determine strain correlations and identify potential transmission clusters. RESULTS: Overall, 15 different STs were found; the predominant ones included ST307 (35, 40.2%), ST512/1519 (15, 17.2%), ST20 (12, 13.8%), and ST101 (7, 8.1%). 33 (37.9%) KPC-Kp strains were noticed to be in five transmission clusters (median number of isolates in each cluster: 5 [3-10]), four of them characterized by intra-hospital transmission. All 87 strains harbored Tn4401a transposon, carrying blaKPC-3 (48, 55.2%), blaKPC-2 (38, 43.7%), and in one case (1.2%) blaKPC-33, the latter gene conferred resistance to ceftazidime/avibactam (CZA). Thirty strains (34.5%) harbored porin mutations; of them, 7 (8.1%) carried multiple Tn4401a copies. These strains were characterized by significantly higher CZA minimum inhibitory concentration compared with strains with no porin mutations or single Tn4401a copy, respectively, even if they did not overcome the resistance breakpoint of 8 ug/mL. Median 2 (IQR:1-2) virulence factors per strain were detected. The lowest number was observed in ST20 compared to the other STs (p<0.001). While ST307 was associated with infection events, a trend associated with colonization events could be observed for ST20. CONCLUSIONS: Integration of genomic, resistance score, and clinical data allowed us to define a relative diversification of KPC-Kp in Northern Italy between 2019 and 2021, characterized by few large transmission chains and rare inter-hospital transmission. Our results also provided initial evidence of correlation between KPC-Kp genomic signatures and higher MIC levels to some antimicrobial agents or colonization/infection status, once again underlining WGS's importance in bacterial surveillance.

Genetic barriers more than environmental associations explain Serratia marcescens population structure.

Bacterial species often comprise well-separated lineages, likely emerged and maintained by genetic isolation and/or ecological divergence. How these two evolutionary actors interact in the shaping of bacterial population structure is currently not fully understood. In this study, we investigate the genetic and ecological drivers underlying the evolution of Serratia marcescens, an opportunistic pathogen with high genomic flexibility and able to colonise diverse environments. Comparative genomic analyses reveal a population structure composed of five deeply-demarcated genetic clusters with open pan-genome but limited inter-cluster gene flow, partially explained by Restriction-Modification (R-M) systems incompatibility. Furthermore, a large-scale research on hundred-thousands metagenomic datasets reveals only a partial habitat separation of the clusters. Globally, two clusters only show a separate gene composition coherent with ecological adaptations. These results suggest that genetic isolation has preceded ecological adaptations in the shaping of the species diversity, an evolutionary scenario coherent with the Evolutionary Extended Synthesis.

Anti-spike antibody level is associated with the risk of clinical progression among subjects hospitalized with COVID-19 pneumonia: results from a retrospective cohort study.

PURPOSE: Antibodies against SARS-CoV-2 spike (anti-S) may confer protection against symptomatic COVID-19. Whether their level predicts progression among those with COVID-19 pneumonia remains unclear. METHODS: We conducted a retrospective cohort study to assess predictors of anti-S levels and whether anti-S titer is associated with death or mechanical ventilation (MV). Adults hospitalized for COVID-19 pneumonia between July 2021 and July 2022 were enrolled if anti-S had been measured within 72 h of admission. Predictors of anti-S level were explored using multivariable quantile regression. The association between anti-S levels and 30-day death/MV was investigated via multivariable logistic regression. Analyses were stratified by vaccine status. RESULTS: The median anti-S level was 1370 BAU/ml in 328 vaccinated and 15.5 BAU/ml in 206 unvaccinated individuals. Among the vaccinated, shorter symptom duration (p = 0.001), hematological malignancies (p = 0.002), and immunosuppressive therapy (p = 0.004) were associated with lower anti-S levels. In the unvaccinated group, symptom duration was the only predictor of anti-S levels (p < 0.001). After 30 days, 134 patients experienced death or MV. Among vaccinated individuals, higher anti-S levels correlated significantly with lower death/MV risk (per log2 increase, OR 0.88, 95%CI 0.81-0.97), irrespective of age and solid malignancies. Among unvaccinated, a marginally protective effect was observed (OR 0.86, 95%CI 0.73-1.01), independent of age, immunosuppressive therapy, and diabetes. Adjustment for monoclonal antibody treatment strengthened the association (OR 0.81, 95%CI 0.68-0.96). CONCLUSION: This study suggests that levels of anti-S antibodies can predict critical or fatal outcomes in COVID-19 pneumonia patients, regardless of vaccination. Whether anti-S Ab could guide risk assessment and vaccination boosting merits further evaluation.

Cultivation and sequencing-free protocol for Serratia marcescens detection and typing.

Serratia marcescens is an opportunistic pathogen that survives in inhospitable environments causing large outbreaks, particularly in neonatal intensive care units (NICUs). Genomic studies revealed that most S. marcescens nosocomial infections are caused by a specific clone (here "Infectious clone"). Whole genome sequencing (WGS) is the only portable method able to identify this clone, but it requires days to obtain results. We present a cultivation-free hypervariable-locus melting typing (HLMT) protocol for the fast detection and typing of S. marcescens, with 100% detection capability on mixed samples and a limit of detection that can reach the 10 genome copies. The protocol was able to identify the S. marcescens infectious clone with 97% specificity and 96% sensitivity when compared to WGS, yielding typing results portable among laboratories. The protocol is a cost and time saving method for S. marcescens detection and typing for large environmental/clinical surveillance screenings, also in low-middle income countries.

Increased circulation of echovirus 11 in the general population and hospital patients as elicited by the non-polio enterovirus laboratory-based sentinel surveillance in northern Italy, 2023.

OBJECTIVES: Following the alert of echovirus 11 (E-11) infection in neonates in EU/EEA Member States, we conducted an investigation of E-11 circulation by gathering data from community and hospital surveillance of enterovirus (EV) in northern Italy from 01 August 2021 to 30 June 2023. METHODS: Virological results of EVs were obtained from the regional sentinel surveillance database for influenza-like illness (ILI) in outpatients, and from the laboratory database of ten hospitals for inpatients with either respiratory or neurological symptoms. Molecular characterization of EVs was performed by sequence analysis of the VP1 gene. RESULTS: In our ILI series, the rate of EV-positive specimens showed an upward trend from the end of May 2023, culminating at the end of June, coinciding with an increase in EV-positive hospital cases. The E-11 identified belonged to the D5 genogroup and the majority (83%) were closely associated with the novel E-11 variant, first identified in severe neonatal infections in France since 2022. E-11 was identified sporadically in community cases until February 2023, when it was also found in hospitalized cases with a range of clinical manifestations. All E-11 cases were children, with 14 out of 24 cases identified through hospital surveillance. Of these cases, 60% were neonates, and 71% had severe clinical manifestations. CONCLUSION: Baseline epidemiological data collected since 2021 through EV laboratory-based surveillance have rapidly tracked the E-11 variant since November 2022, alongside its transmission during the late spring of 2023.

The diagnostic performances of the Atellica® 1500 automated urinalysis system for ruling out bacterial urinary tract infection.

Urinary tract infection (UTI) is one of the most common diseases occurring in both hospitalized and community subjects. Urine culture is the gold standard test for the diagnosis of UTI, but approximately 80% are negative. The aim of this study was to evaluate the performance of the automated urinalysis system Atellica® 1500 (Siemens Healthineers, Erlangen, Germany) as screening tool for ruling out UTI. A total of 5,490 urine specimens from outpatients, that had simultaneous requests for urinalysis and urine culture, were evaluated. Of the 5,490 samples, 833 (15.2 %) resulted positive for urine culture. Among UTI-related parameters, bacterial count was considered the most apt to be diagnostic of subjects affected by UTI. Using a cutoff value for bacteria count equal to 180 elements/µL, Atellica® 1500 detected bacteriuria with diagnostic sensitivity (Se) of 88.1 %, diagnostic specificity (Sp) of 82.1 %, and negative predictive value (NPV) of 95.2 %. Comparing our results with the literature's data, we observed that our Se and NPV were lower, while our Sp was higher. Our data showed that the Atellica® 1500 system detected bacteria with satisfactory analytical performance, but the results obtained do not make it a reliable tool for excluding UTI with urinalysis.

Impact of SARS-CoV-2 Omicron and Delta variants in patients requiring intensive care unit (ICU) admission for COVID-19, Northern Italy, December 2021 to January 2022.

This multicenter observational study included 171 COVID-19 adult patients hospitalized in the ICUs of nine hospitals in Lombardy (Northern Italy) from December, 1st 2021, to February, 9th 2022. During the study period, the Delta/Omicron variant ratio of cases decreased with a delay of two weeks in ICU patients compared to that in the community; a higher proportion of COVID-19 unvaccinated patients was infected by Delta than by Omicron whereas a higher rate of COVID-19 boosted patients was Omicron-infected. A higher number of comorbidities and a higher comorbidity score in ICU critically COVID-19 inpatients was positively associated with the Omicron infection as well in vaccinated individuals. Although people infected by Omicron have a lower risk of severe disease than those infected by Delta variant, the outcome, including the risk of ICU admission and the need for mechanical ventilation due to infection by Omicron versus Delta, remains uncertain. The continuous monitoring of the circulating SARS-CoV-2 variants remains a milestone to counteract this pandemic.

Humoral and cellular immune response in patients with hematological disorders after two doses of BNT162b2 mRNA COVID-19 vaccine: A single-center prospective observational study (NCT05074706).

Hematological patients at higher risk of severe COVID-19 were excluded from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine trials. In this single-center observational prospective study (NCT05074706), we evaluate immune response in the hematological patients followed at the Hematological Division of San Gerardo Hospital, Monza (Italy) deemed to be severely immunosuppressed after vaccination with two doses of the BNT162b2 vaccine. Anti-SARS-CoV-2 immunoglobulin G titers above the cutoff value of 33.8 BAU/ml were detected in 303 (80.2%) out of the 378 patients enrolled. Patients with lymphoproliferative disorders had a significant lower probability of immunization (43.2% vs. 88.4%, p < 0.001). Patients treated with anti-CD20 showed a significantly lower probability of immunization compared to all other treatments (21.4%, p < 0.0001). Among 69 patients who failed seroconversion, 15 patients (22.7%) showed a positive T-cell response. Patients previously treated with anti-CD20 were 2.4 times more likely to test positive for T-cell responses (p = 0.014). Within a follow-up of 9 months from the second COVID-19 vaccination, symptomatic SARS-CoV-2 infections were reported by 20 patients (5.3%) and four of them required hospitalization. Successful serological or T-cell-mediated immunization conferred protection from symptomatic COVID-19. Patients treated with anti-CD20 who were not seroconverted after vaccination might still be protected from COVID-19 due to the T-cell immune response.

Hypervariable-Locus Melting Typing: a Novel Approach for More Effective High-Resolution Melting-Based Typing, Suitable for Large Microbiological Surveillance Programs.

Pathogen typing is pivotal to detecting the emergence of high-risk clones in hospital settings and to limit their spread. Unfortunately, the most commonly used typing methods (i.e., pulsed-field gel electrophoresis [PFGE], multilocus sequence typing [MLST], and whole-genome sequencing [WGS]) are expensive or time-consuming, limiting their application to real-time surveillance. High-resolution melting (HRM) can be applied to perform cost-effective and fast pathogen typing, but developing highly discriminatory protocols is challenging. Here, we present hypervariable-locus melting typing (HLMT), a novel approach to HRM-based typing that enables the development of more effective and portable typing protocols. HLMT types the strains by assigning them to melting types (MTs) on the basis of a reference data set (HLMT-assignment) and/or by clustering them using melting temperatures (HLMT-clustering). We applied the HLMT protocol developed on the capsular gene wzi for Klebsiella pneumoniae on 134 strains collected during surveillance programs in four hospitals. Then, we compared the HLMT results to those obtained using wzi, MLST, WGS, and PFGE typing. HLMT distinguished most of the K. pneumoniae high-risk clones with a sensitivity comparable to that of PFGE and MLST+wzi. It also drew surveillance epidemiological curves comparable to those obtained using MLST+wzi, PFGE, and WGS typing. Furthermore, the results obtained using HLMT-assignment were consistent with those of wzi typing for 95% of the typed strains, with a Jaccard index value of 0.9. HLMT is a fast and scalable approach for pathogen typing, suitable for real-time hospital microbiological surveillance. HLMT is also inexpensive, and thus, it is applicable for infection control programs in low- and middle-income countries. IMPORTANCE In this work, we describe hypervariable-locus melting typing (HLMT), a novel fast approach to pathogen typing using the high-resolution melting (HRM) assay. The method includes a novel approach for gene target selection, primer design, and HRM data analysis. We successfully applied this method to distinguish the high-risk clones of Klebsiella pneumoniae, one of the most important nosocomial pathogens worldwide. We also compared HLMT to typing using WGS, the capsular gene wzi, MLST, and PFGE. Our results show that HLMT is a typing method suitable for real-time epidemiological investigation. The application of HLMT to hospital microbiology surveillance can help to rapidly detect outbreak emergence, improving the effectiveness of infection control strategies.

Anti-SARS-CoV-2 IgG antibodies induced by the BNT162b2 mRNA vaccine is age-dependent and influenced by a previous natural SARS-CoV-2 infection.

BACKGROUND AND AIM: our study aimed to investigate the association between anti-SARS-CoV-2 IgG level after two doses of BNT162b2 vaccine and the previously infected/infection-naïve status, age, and gender in a population of health care workers (HCWs). METHODS: all the population of immunocompetent HCWs were vaccinated with two doses of BNT162b2 based on a technical data sheet. SARS-CoV-2 IgG assay was performed 25 to 32 days after the second dose. Anti-SARS-CoV-2 IgG level was used as a categorical variable, since 2080 BAU/ml was the median IgG value. The multivariate logistic regression model included the previously infected/infection-naïve status, age groups, and gender. RESULTS: All HCWs tested were seropositive. The odds ratio (OR) for anti-SARS-CoV-2 IgG> 2080 BAU / ml between previously infected and infection-naïve HCWs was 2.05 [95% CI 1.1-3.8].  Older age groups had lower percentage of HCWs with anti-SARS-CoV-2 IgG> 2080 BAU / mL than younger groups. Finally, no association between gender and IgG level was found. CONCLUSIONS: our study showed an excellent antibody response to vaccination with BNT162b2 after two doses. A significant difference was observed between anti-SARS-CoV-2 IgG level with age and previous SARS-CoV-2 infection status.

Re-emergence of enterovirus D68 in Europe after easing the COVID-19 lockdown, September 2021.

We report a rapid increase in enterovirus D68 (EV-D68) infections, with 139 cases reported from eight European countries between 31 July and 14 October 2021. This upsurge is in line with the seasonality of EV-D68 and was presumably stimulated by the widespread reopening after COVID-19 lockdown. Most cases were identified in September, but more are to be expected in the coming months. Reinforcement of clinical awareness, diagnostic capacities and surveillance of EV-D68 is urgently needed in Europe.

HPV 16 and 18 contribute to development of anal dysplasia in HIV infection irrespective of gender and sexual orientation.

OBJECTIVES: The aim of the present study was too investigate prevalence and persistence of human papilloma virus (HPV) and cytological abnormalities (CAs) in the anal swabs of people living with HIV (PLWH): men who have sex with men (MSM), men who have sex with women (MSW) and women (W). METHODS: Between March 2010 and January 2019, an anal swab for cytological and HPV genotyping tests was offered to all PLWH attending our clinic. Logistic regression analysis was conducted to identify predictors of infection. RESULTS: In all, 354 PLWH were screened: 174 MSM, 90 MSW and 61 W. Prevalence of at least one high-risk (HR) HPV was higher in MSM (91%) and W (85%) than in MSW (77%) (P < 0.05). Cytological abnormalities were found in 21.1% of the entire population. At multivariable regression analysis a lower risk for HPV infection was found for W than for MSM [odds ratio = 0.24 (95% confidence interval: 0.115-0.513)] and for MSW than for MSM [0.37 (0.180-0.773)] and there was a significantly higher risk of CAs in PLWH with HPV 16 and 18 [3.3 (1.04-10.49)]. A total of 175 PLWH (103 MSM, 33 MSW and 26 W) had at least one follow-up visit (T1) after a median (interquartile range) follow-up of 3.6 (2.1-5.7) years. The acquisition rate of HR-HPV was high, with 66.7% of PLWH negative for HR-HPV at T0 who became positive at T1 (P < 0.001). The prevalence of CAs was stable (20.6%). A significant association between CAs at T1 and persistence of HPV-16 and/or 18 was found (P < 0.05). CONCLUSIONS: HPV 16 and 18 are associated with the presence and development of CAs irrespective of sexual orientation.

Case Report: Concomitant Massive Cerebral Venous Thrombosis and Internal Iliac Vein Thrombosis Related to Paucisymptomatic COVID-19 Infection.

Thrombotic complications are common in COVID-19 patients, but cerebral venous system involvement, timing after infection, optimal treatment, and long-term outcome are uncertain. We report a case of massive cerebral venous thrombosis and concomitant internal iliac vein thrombosis occurring in the late phase of paucisymptomatic COVID-19 infection. Mild respiratory symptoms, without fever, started 3 weeks before headache and acute neurological deficits. The patient had silent hypoxemia and typical COVID-19 associated interstitial pneumonia. Brain CT scan showed a left parietal hypodense lesion with associated sulcal subarachnoid hemorrhage. CT cerebral venography showed a massive cerebral venous thrombosis involving the right transverse sinus, the right jugular bulb, the superior sagittal sinus, the straight sinus, the vein of Galen, and both internal cerebral veins. Abdominal CT scan showed no malignancy but revealed an asymptomatic right internal iliac vein thrombosis. Both cerebral venous thrombosis and pelvic vein thrombosis were effectively treated with unfractionated heparin started on the day of admission, then shifted to low molecular weight heparin, with a favorable clinical course. Nasopharyngel swab, repeated twice, tested negative for SARS-CoV-2. Serological tests confirmed SARS-CoV-2 infection. Our case supports active surveillance and prevention of thrombotic complications associated with COVID-19, which may affect both peripheral and cerebral venous system. Early initiation of unfractionated heparin may lead to good neurologic outcome.

Clinical Usefulness of Klebsiella Pneumoniae Carbapenemase-Producing K. Pneumoniae Genotyping: The Experience of a Single-Center Epidemic.

BACKGROUND: During the last decade, the spread of Klebsiella pneumoniae-carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) has increased dramatically worldwide. In this scenario, growing interest has been addressed to genotyping of KPC-Kp strains, which emerged as an important tool for a better understanding of the epidemiological and clinical characteristics of the outbreaks. METHODS: We performed a retrospective cohort study on patients infected with KPC-Kp during a 28-month outbreak period (January 2010-April 2012) at San Gerardo Hospital (Monza, Italy), investigating KPC-Kp genotypes by means of repetitive element sequence-based polymerase chain reaction (Rep-PCR). RESULTS: We enrolled 97 patients infected with KPC-Kp. Rep-PCR analysis identified 5 distinct clone types, with different distribution over time. During the first 12 months of the outbreak period, only 1 clone was detected (clone A, in 47 patients), while the 4 other clones were identified over the remaining 16 months (clones C, E, and F/L in 23, 24, and 3 patients respectively). Mechanical ventilation was less frequent in patients infected with clones C/E/F/L (OR = 0.14; 95% CI: 0.05-0.37) compared to clone A, and the Charlson comorbidity index (CI) was more likely to have a score >5 in patients infected with clones C/E/F/L (OR = 7.21; 95% CI: 2.24-23.14) compared to clone A.Overall mortality was higher in patients infected with clones C/E/F/L (13/20 patients, 65%) compared to those infected with clone A (7/20, 35%). Mortality in patients infected with clones C/E/F/L remained significantly higher even after adjusting for the potential confounding effect of comorbidities (ie, CI), with a hazard ratio (HR) of 4.65 (95% CI: 1.83-11.89). CONCLUSIONS: Our results suggested a close relationship between strain genotype and clinical outcome.

Vascular homograft use in a femoropopliteal rare bacterial infection bypass.

We report on a patient with a femoropopliteal bypass infected by Kytococcus sedentarius. Treatment consisted of resection of the infected prosthesis with homograft substitution and antibiotic therapy started postoperatively. At 6 months followup, the patient showed no signs of infection and results of laboratory findings were normal.

Acute hyperglycemia and contrast-induced nephropathy in primary percutaneous coronary intervention.

BACKGROUND: Acute hyperglycemia and contrast-induced nephropathy (CIN) are frequently observed in ST-elevation acute myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI), and both are associated with an increased mortality rate. We investigated the possible association between acute hyperglycemia and CIN in patients undergoing primary PCI. METHODS: We prospectively enrolled 780 STEMI patients undergoing primary PCI. For each patient, plasma glucose levels were assessed at hospital admission. Acute hyperglycemia was defined as glucose levels>198 mg/dL (11 mmol/L). Contrast-induced nephropathy was defined as an increase in serum creatinine>25% from baseline in the first 72 hours. RESULTS: Overall, 148 (19%) patients had acute hyperglycemia; and 113 (14.5%) patients developed CIN. Patients with acute hyperglycemia had a 2-fold higher incidence of CIN than those without acute hyperglycemia (27% vs 12%, P<.001). In-hospital mortality was higher in patients with acute hyperglycemia than in those without acute hyperglycemia (12% vs 3%, P<.001). Mortality rate was also higher in patients developing CIN than in those without this renal complication (27% vs 0.9%, P<.001). Patients with acute hyperglycemia that developed CIN had the highest mortality rate (38%). Acute hyperglycemia was an independent predictor of CIN and in-hospital mortality. CONCLUSIONS: In STEMI patients undergoing primary PCI, acute hyperglycemia is associated with an increased risk for CIN and with increased in-hospital mortality.

Circulating cytochrome c as potential biomarker of impaired reperfusion in ST-segment elevation acute myocardial infarction.

In patients with ST-segment elevation acute myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI), abrupt reperfusion can induce myocardial injury and apoptotic cell death. Reperfusion-induced myocardial damage, however, cannot be easily evaluated in clinical practice because of the lack of specific biomarkers. Cytochrome c, a mitochondrial protein, is released on reperfusion into the cytosol, where it triggers the apoptotic process. It can reach the external fluid and circulating blood when cell rupture occurs. We measured the cytochrome c circulating levels in patients with STEMI undergoing pPCI, and correlated them with the clinical signs of myocardial necrosis and reperfusion. The plasma creatine kinase-MB mass and serum cytochrome c (enzyme-linked immunosorbent assay method) were serially measured in 55 patients with STEMI undergoing pPCI. The angiographic and electrocardiographic signs of myocardial reperfusion were also assessed. Cytochrome c transiently increased in all patients with STEMI, with a curve that paralleled that of creatine kinase-MB. A significant relation was found between the peak values of the 2 biomarkers (R = 0.35, p = 0.01) and between the areas under the 2 curves (R = 0.33, p = 0.02). The creatine kinase-MB peak value correlated significantly with the clinical features of infarct extension. In contrast, the cytochrome c peak value correlated inversely with the myocardial blush grade. Patients with clinical signs of myocardial reperfusion injury had a significantly greater cytochrome c peak value than patients without reperfusion injury (median 1.65 ng/ml, interquartile range 1.20 to 2.20, vs 1.1 ng/ml, interquartile range 0.65 to 1.55; p = 0.04). In conclusion, serum cytochrome c is detectable in the early phase of STEMI treated with pPCI and is associated with clinical signs of impaired myocardial reperfusion.