Successful containment and infection control of a Carbapenem-resistant Klebsiella pneumoniae outbreak in an Italian hospital

We describe an outbreak of a carbapenemase-producing Klebsiella pneumoniae sequence type 258 (ST258) clone in an Italian hospital during two months in 2010. The rapid detection and management of the eleven patients colonized and infected with KPC-producing K.pneumoniae curbed the spread of this multidrug-resistant organism.

A model of laboratory surveillance for neuro-arbovirosis applied during 2012 in the Emilia-Romagna region, Italy

Arboviruses with neuroinvasive potential are gaining more attention due to the increased number of cases of autochthonous and imported infections in the human host. Diagnosis of infection caused by these viruses in patients with central nervous system (CNS) diseases is still underestimated and these infections represent an emerging threat to public health. We describe a model suitable for the laboratory surveillance of neuro-arbovirosis that was applied in the Emilia-Romagna region, north-eastern Italy, during the 2012 summer season. One hundred and twenty cases of suspected neuroinvasive infection were tested for arboviral agents on the basis of clinical and laboratory signs and epidemiological data. The most common virus detected was Toscana virus (TOSV): anti-TOSV specific antibodies or viral components were detected in 28.3% of the cases; 79.4% of the TOSV cases were in the acute phase of infection. No cases resulted in acute phase for West Nile (WNV), Usutu (USUV), Chikungunya (CHIKV) or Dengue (DENV) virus infection. Conversely, two patients with a history of staying in a tick-borne encephalitis virus (TBEV) endemic area showed a probable TBEV infection. These results emphasize the importance of a complete and 'ready to act' laboratory diagnostic system to be implemented within the larger frame of a regional integrated surveillance system.

Pneumococcal carriage in young children one year after introduction of the 13-valent conjugate vaccine in Italy

BACKGROUND

In mid 2010, the 7-valent pneumococcal conjugate vaccine (PCV7) was replaced by the 13-valent conjugate vaccine (PCV13) for childhood immunization in Italy. Our objective in this study was to obtain a snapshot of pneumococcal carriage frequency, colonizing serotypes, and antibiotic resistance in healthy children in two Italian cities one year after PCV13 was introduced.

METHODS

Nasopharyngeal swabs were obtained from 571 children aged 0-5 years from November 2011-April 2012. Pneumococcal isolates were serotyped and tested for antimicrobial susceptibility. Penicillin and/or erythromycin non-susceptible isolates were analyzed by Multi Locus Sequence Typing (MLST).

RESULTS

Among the children examined, 81.2% had received at least one dose of PCV7 or PCV13 and 74.9% had completed the recommended vaccination schedule for their age. Among the latter, 57.3% of children had received PCV7, 27.1% PCV13, and 15.6% a combination of the two vaccines. The overall carriage rate was 32.9%, with children aged 6-35 months the most prone to pneumococcal colonization (6-23 months OR: 3.75; 95% CI: 2.19-6.43 and 24-35 months OR: 3.15, 95%CI: 2.36-4.22). A total of 184 pneumococcal isolates were serotyped and divided into PCV7 (5.4%), PCV13 (18.0%), and non-PCV13 (82.0%) serotypes. Serotypes 6C, 24F, and 19A were the most prevalent (10.3%, 8.6%, and 8.1%, respectively). The proportion of penicillin non-susceptible (MIC >0.6 mg/L) isolates was 30.9%, while 42.3% were erythromycin resistant. Non-PCV13 serotypes accounted for 75.4% and 70.8% of the penicillin and erythromycin non-susceptible isolates, respectively.

CONCLUSIONS

Our results revealed low rates of PCV7 and PCV13 serotypes in Italian children, potentially due to the effects of vaccination. As the use of PCV13 continues, its potential impact on vaccine serotypes such as 19A and cross-reactive serotypes such as 6C will be assessed, with this study providing a baseline for further analysis of surveillance isolates.

Human fetal inner ear involvement in congenital cytomegalovirus infection

Background

Congenital cytomegalovirus (CMV) infection is a leading cause of sensorineural hearing loss (SNHL). The mechanisms of pathogenesis of CMV-related SNHL are still unclear. The aim is to study congenital CMV-related damage in the fetal inner ear, in order to better understand the underlying pathophysiology behind CMV-SNHL.

Results

We studied inner ears and brains of 20 human fetuses, all at 21 week gestational age, with a high viral load in the amniotic fluid, with and without ultrasound (US) brain abnormalities. We evaluated histological brain damage, inner ear infection, local inflammatory response and tissue viral load.

Immunohistochemistry revealed that CMV was positive in 14/20 brains (70%) and in the inner ears of 9/20 fetuses (45%). In the cases with inner ear infection, the marginal cell layer of the stria vascularis was always infected, followed by infection in the Reissner’s membrane. The highest tissue viral load was observed in the inner ear with infected Organ of Corti. Vestibular labyrinth showed CMV infection of sensory cells in the utricle and in the crista ampullaris.

US cerebral anomalies were detected in 6 cases, and in all those cases, the inner ear was always involved. In the other 14 cases with normal brain scan, histological brain damage was present in 8 fetuses and 3 of them presented inner ear infection.

Conclusions

CMV-infection of the marginal cell layer of the stria vascularis may alter potassium and ion circulation, dissipating the endocochlear potential with consequent SNHL. Although abnormal cerebral US is highly predictive of brain and inner ear damage, normal US findings cannot exclude them either.

Clinical application of a molecular method based on real time RT-PCR for detection of influenza A(H1N1)v virus

Given the new diagnostic need following the pandemic caused by the A(H1N1)v virus, we evaluated the performance characteristics of Xpert® Flu assay (Cepheid). The overall sensitivity and specificity were 65.6% and 92.8%, respectively. Sensitivity and specificity for A(H1N1)v virus were 85.7% and 94.9%, respectively, and therefore the Xpert® Flu assay is suitable for a rapid diagnosis in critically ill patients where diagnosis is crucial for clinical management and for an appropriate public health response.

Persistence of anti-West Nile virus-specific antibodies among asymptomatic blood donors in northeastern Italy

The development and persistence of anti-West Nile Virus (WNV) immunoglobulin G (IgG)- and IgM-specific antibodies were investigated in 68 asymptomatic blood donors (BDs) previously tested as positive between October, 2008, and September, 2009, and living in northeastern Italy. Our study showed that WNV-specific IgG titers became negative (41%) or decreased (33%) in a large percentage of BDs, while they increased in a smaller percentage (10%); 16% of BDs showed no titer variation. Reversion to seronegative status within a short time frame suggests that WNV surveillance should be maintained year after year.

Ongoing outbreak of visceral leishmaniasis in Bologna Province, Italy, November 2012 to May 2013

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Ongoing outbreak of visceral leishmaniasis in Bologna Province, Italy, November 2012 to May 2013

An increased number of autochthonous visceral leishmaniasis (VL) cases has recently been reported in Bologna Province in northern Italy. Over six months from November 2012 to May 2013, 14 cases occurred, whereas the average number of cases per year was 2.6 (range: 0-8) in 2008 to 2012. VL was diagnosed in a median of 40 days (range: 15-120) from disease onset. This delay in diagnosis shows the need for heightened awareness of clinicians for autochthonous VL in Europe.

Comparative genomic and phylogenetic analysis of the first Usutu virus isolate from a human patient presenting with neurological symptoms

Usutu virus (USUV) is a mosquito-borne flavivirus, belonging to the Japanese encephalitis antigenic complex, that circulates among mosquitoes and birds. We describe and analyze the complete genome sequence of the first USUV strain isolated from an immunocompromised patient with neuroinvasive disease. This USUV isolate showed an overall nucleotide identity of 99% and 96%, respectively, with the genomes of isolates from Europe and Africa. Comparison of the human USUV complete polyprotein sequence with bird-derived strains, showed two unique amino acid substitutions. In particular, one substitution (S595G) was situated in the DIII domain of the viral Envelope protein that is recognized by flavivirus neutralizing antibodies. An additional amino acid substitution (D3425E) was identified in the RNA-dependent RNA polymerase (RdRp) domain of the NS5 protein. This substitution is remarkable since E3425 is highly conserved among the other USUV isolates that were not associated with human infection. However, a similar substitution was observed in Japanese encephalitis and in West Nile viruses isolated from humans. Phylogenetic analysis of the human USUV strain revealed a close relationship with an Italian strain isolated in 2009. Analysis of synonymous nucleotide substitutions (SNSs) among the different USUV genomes showed a specific evolutionary divergence among different countries. In addition, 15 SNSs were identified as unique in the human isolate. We also identified four specific nucleotide substitutions in the 5' and 3' untranslated regions (UTRs) in the human isolate that were not present in the other USUV sequences. Our analyses provide the basis for further experimental studies aimed at defining the effective role of these mutations in the USUV genome, their potential role in the development of viral variants pathogenic for humans and their evolution and dispersal out of Africa.

Innate host responses to West Nile virus: Implications for central nervous system immunopathology

West Nile virus (WNV) is an emerging neurotropic flavivirus that has recently spread to America and Southern Europe via an enzootic/epizootic bird-mosquito-bird transmission cycle. The virus can occasionally infect humans through mosquito bites, and man-to-man transmission has also been reported via infected blood or organ donation. In the human host, WNV causes asymptomatic infection in about 70%-80% of cases, while < 1% of clinical cases progress to severe neuroinvasive disease; long-term neurological sequelae are common in more than 50% of these severe cases. The pathogenesis of the neuroinvasive form of WNV infection remains incompletely understood, and risk factors for developing severe clinical illness are largely unknown. The innate immune response plays a major role in the control of WNV replication, which is supported by the fact that the virus has developed numerous mechanisms to escape the control of antiviral interferons. However, exaggerated inflammatory responses lead to pathology, mainly involving the central nervous system. This brief review presents the salient features of innate host responses, WNV immunoevasion strategies, and WNV-induced immunopathology.

Detection of specific antibodies against West Nile and Usutu viruses in healthy blood donors in northern Italy, 2010-2011

Neutralizing antibodies against West Nile (WNV) and Usutu (USUV) viruses were measured in 6000 samples collected, between 1 September 2010 and 30 June 2011, from blood donors living in different districts of Emilia-Romagna, northeastern Italy. On the basis of the microneutralization assay (MNTA), 47 (0.78%) subjects were positive for WNV and 14 (0.23%) for USUV. These results were compared with those obtained 2 years ago and suggest an increased circulation of USUV among humans in Emilia-Romagna.

West Nile virus in Europe: emergence, epidemiology, diagnosis, treatment, and prevention

West Nile virus (WNV), a mosquito-borne flavivirus in the Japanese encephalitis antigenic group, has caused sporadic outbreaks in humans, horses and birds throughout many of the warmer regions of Europe for at least 20 years. Occasional cases of West Nile encephalitis have also been associated with infected blood transfusions and organ donations. Currently, WNV appears to be expanding its geographical range in Europe and causing increasing numbers of epidemics/outbreaks associated with human morbidity and mortality. This brief review reports on the current epidemic situation regarding WNV in Europe, highlighting the clinical, diagnostic and preventive measures available for controlling this apparently emerging human pathogen.

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-β-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.

Heterogeneity of West Nile virus genotype 1a in Italy, 2011

West Nile virus (WNV) is currently circulating in several European countries and, over recent decades, concomitantly with enhanced surveillance studies and improved diagnostic capabilities, an increase in the geographical distribution and in the number of cases in Europe has been documented. In Italy in 2011, 14 human cases of WNV neuroinvasive infections due to lineage 1 strains were registered in several Italian regions. Here we report WNV partial sequences obtained from serum samples of two patients living in different regions of Italy (Veneto and Sardinia). Phylogenetic analysis, performed on a fragment (566 nt) of the envelope gene, showed that WNV strains circulating in Italy in 2011 belong to lineage 1a, but are different from lineage 1a strains isolated in 2008–2009.The data reported here are consistent with the hypothesis of multiple recent introductions of WNV lineage 1a strains into Italy.

Seroprevalence of West Nile virus antibodies in blood donors living in the metropolitan area of Milan, Italy, 2009-2011

A seroprevalence study for anti-West Nile virus-specific antibodies was carried out in healthy blood donors resident in the metropolitan area of Milan in two different years, 2009 and 2011. In 2009 no positive sera were found, whereas 5 positive sera were found in 2011, revealing viral circulation in this naive area. The seroprevalence rate identified in 2011 was 0.57%, suggesting that the area of WNV circulation in Italy is larger than that previously identified.

Routine use of a real-time polymerase chain reaction method for detection of bloodstream infections in neutropaenic patients

We examined the performance of a real-time polymerase chain reaction (PCR) test (SeptiFast) for early detection of bloodstream infection in febrile neutropaenic patients. Blood samples from 201 patients were screened for pathogens by blood culture and by PCR on the first day of fever. PCR results were available earlier (median 3 days for bacteria, 5 days fungal pathogens; P ≤ 0.01). The sensitivity (0.74) and specificity (0.96) of the PCR test were acceptable for Gram negatives when culture was considered the gold standard, but sensitivity of the test was poorer for Gram-positive organisms (0.39). The PCR assay also led to 22.9% of invalid results. SeptiFast speeds the microbiological diagnosis of bloodstream infection in neutropaenic patients. However, the frequent failure of instrumental control procedures, the relatively poor sensitivity of the test, and the lack of phenotypic data on antimicrobial susceptibility associated with its high costs suggest that this assay cannot replace the blood cultures.

Congenital cytomegalovirus infection: patterns of fetal brain damage

Cytomegalovirus (CMV) is the most prevalent infectious agent causing neurological dysfunction in the developing brain. This study analysed the different patterns of tissue damage, particularly in the brain, of fetuses with documented CMV infection. We studied 45 fetuses at 20-21 weeks of gestation with congenital CMV infection documented by invasive positive prenatal diagnosis. At the time of amniocentesis, abnormal ultrasound findings had been recorded for 13 of the 45 fetuses (29%). Histological and immunohistochemical characterization was performed on the placenta, brain, heart, lung, liver, kidney, and pancreas. The different degrees of brain damage were correlated with tissue viral load, inflammatory response, placental functionality, and extramedullary haematopoiesis. Even though a high CMV load was detected in all amniotic fluids, brain infection occurred in only 62% of the fetuses and with different degrees of severity. Tissues with a low viral load showed a globally weak inflammatory response, and fetuses had only mild brain damage, whereas tissues with a high CMV load showed prominent infiltration of the activated cytotoxic CD8(+) T-lymphocytes responsible for immune-mediated damage. Furthermore, severe placental infection was associated with diffuse villitis and necrosis, consistent with functional impairment and possible consequent hypoxic cerebral damage. Brain injury induced by CMV congenital infection may be the result of uncontrolled viral replication, immune-mediated damage by cytotoxic CD8(+) T-lymphocytes, and, in the presence of placental insufficiency, fetal hypoxia.

High TNF-alpha and IL-8 levels predict low blood dendritic cell counts in primary cytomegalovirus infection

BACKGROUND

In vitro studies suggest that human cytomegalovirus (CMV) modulates the functions of dendritic cells (DCs). However, there are limited data on DC homeostasis in CMV-infected patients.

OBJECTIVES

The aim of this study was to characterize circulating DCs and plasma cytokine levels in immunocompetent patients with primary, symptomatic CMV infections.

STUDY DESIGN

The study population consisted of 14 patients suffering of CMV mononucleosis and 14 healthy volunteers (11 CMV-seropositive and 3 CMV-seronegative subjects) included as controls. Peripheral blood mononuclear cells were isolated and used to characterize DCs and to quantify CMV in the blood. Plasma levels of pro-inflammatory and anti-inflammatory cytokines were also measured.

RESULTS

We observed that patients who were developing CMV mononucleosis presented lower myeloid and plasmacytoid DC counts in peripheral blood compared with healthy controls. We also noted elevated levels of inflammatory mediators, of which tumor necrosis factor-α (TNF-α)-which activates DCs and endothelial cells-was the highest. Notably, the decrease in blood DCs correlated with high TNF-α and IL-8 levels by a hyperbolic function.

CONCLUSIONS

Our results suggest that increased levels of inflammatory factors facilitate alterations in DC homeostasis during primary CMV infection, which may contribute to viral-induced modulation of host immunity.

Detection of Usutu-virus-specific IgG in blood donors from northern Italy

We developed a novel enzyme-linked immunosorbent assay to detect the specific IgG response to Usutu virus (USUV) in humans, by evaluating 359 blood donors who were living in northeastern Italy. Our results demonstrate the presence of an anti-USUV response in 4 subjects with no history of other flavivirus infection.