Validation of Armadillo officinalis Dumèril, 1816 (Crustacea, Isopoda, Oniscidea) as a bioindicator: in vivo study of air benzene exposure

This study tests the potential for using Armadillo officinalis as a bioindicator of exposure to and activation of benzene metabolic pathways using an in vivo model. A. officinalis specimens collected in a natural reserve were divided into a control and three test groups exposed to 2.00, 5.32 or 9.09 µg/m(3) benzene for 24h. Three independent tests were performed to assess model reproducibility. Animals were dissected to obtain three pooled tissue samples per group: hepatopancreas (HEP), other organs and tissues (OOT), and exoskeleton (EXO). Muconic acid (MA), S-phenylmercapturic acid (S-PMA), two human metabolites of benzene, and changes in mtDNA copy number, a human biomarker of benzene exposure, were determined in each sample; benzene was determined only in EXO. MA was measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, S-PMA by triple quadrupole mass spectrometer liquid chromatography with electro spray ionization (LC-MS-ESI-TQD), mtDNA by real-time quantitative PCR and end-point PCR, and benzene by quadrupole mass spectrometer head-space gas chromatography (HSGC-MS). MA and S-PMA levels rose both in HEP and OOT; EXO exhibited increasing benzene concentrations; and mtDNA copy number rose in HEP but not in OOT samples. Overall, our findings demonstrate that A. officinalis is a sensitive bioindicator of air benzene exposure and show for the first time its ability to reproduce human metabolic dynamics.

Spread of a carbapenem- and colistin-resistant Acinetobacter baumannii ST2 clonal strain causing outbreaks in two Sicilian hospitals

BACKGROUND

Infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have become an important healthcare-associated problem, particularly in intensive care units (ICUs).

AIM

To investigate the emergence of carbapenem- and colistin-resistant A. baumannii infections in two Sicilian hospitals.

METHODS

From October 2008 to May 2011, a period which included two Italian Nosocomial Infections Surveillance in ICUs network (SPIN-UTI) project surveys, all carbapenem-resistant A. baumannii isolates from the ICUs of two hospitals in Catania, Italy, were prospectively collected. Minimum inhibitory concentrations (MICs) were measured by agar dilution, and phenotypic testing for metallo-β-lactamase (MBL) production was performed. Carbapenem resistance genes and their genetic elements were identified by polymerase chain reaction and sequencing. Genotypic relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Patient-based surveillance was conducted using the SPIN-UTI protocol and previous antibiotic consumption was recorded.

FINDINGS

Twenty-six carbapenem-resistant A. baumannii were identified. Imipenem and meropenem MICs ranged from 4 to >32 mg/L, and 15 isolates exhibited high-level colistin resistance (MICs >32 mg/L). PFGE demonstrated that all isolates belonged to a unique clonal type and were assigned to ST2 of the international clone II. They harboured an intrinsic blaOxA-51-like carbapenemase gene, blaOxA-82, which was flanked upstream by ISAba1.

CONCLUSIONS

The dissemination of clonally related isolates of carbapenem-resistant A. baumannii in two hospitals is described. Simultaneous resistance to colistin in more than half of the isolates is a problem for effective antibiotic treatment. Prior carbapenem and colistin consumption may have acted as triggering factors.

Access to prenatal cytogenetic diagnosis in Catania: a retrospective survey

BACKGROUND

To determine the incidence of chromosome abnormalities (CAs) in prenatal cytogenetic diagnosis, to describe and compare indications in Italian and migrant women, and to assess the level of compliance with published national guidelines.

METHODS

A retrospective analysis of 7806 amniotic fluid samples (AFS) and 228 chorionic villi samples (CVS) was conducted.

RESULTS

Advanced maternal age was the most common indication. CAs incidence was 3.1 per 100 AFS, and 12.6 per 100 CVS. Only parental chromosome rearrangement and ultrasound abnormalities were significantly associated with CA occurrence (RR= 20.15 95%CI: 11.96-33.96; RR= 4.33; 95%CI: 2.95-6.36, respectively). Both in amniocentesis and in chorionic villi sampling CA incidence was significantly higher when performed according to the national guidelines, than for other reasons. Incidence data for trisomy 21, trisomy 18 and inversions were significantly higher than those reported in a previous Italian report.

CONCLUSIONS

Increased maternal age may explain, at least in part, the increase by time of CAs, although an excess was shown in our population independently from it. Our results show that advanced maternal age may not be sufficient as a single criterion for prenatal diagnosis, and suggesting a future revision of national clinical indications is suggested.

Clonal spread and patient risk factors for acquisition of extensively drug-resistant Acinetobacter baumannii in a neonatal intensive care unit in Italy

AIM

To report an outbreak of extensively drug-resistant (XDR) Acinetobacter baumannii in the neonatal intensive care unit (NICU) of an Italian university hospital. Patient risk profiles for acquisition of A. baumannii and measures used to control the outbreak are described.

METHODS

Antibiotic susceptibility of strains was evaluated by microdilution. Genotyping was performed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Carbapenemase genes were analysed by polymerase chain reaction and DNA sequencing. A case-control study was designed to identify risk factors for acquisition of A. baumannii.

FINDINGS

A. baumannii was isolated from 22 neonates, six of whom were infected. One major PFGE type was identified, assigned to sequence type (ST) 2, corresponding to International Clone II; this was indistinguishable from isolates from the adult ICU in the same hospital. A. baumannii isolates were resistant to aminoglycosides, quinolones and classes of β-lactam antibiotics, but were susceptible to tigecycline and colistin. Carbapenem resistance was associated with the presence of transposon Tn2006 carrying the bla(OxA-23) gene. Length of NICU stay, length of exposure to A. baumannii, gestational age, use of invasive devices and length of exposure to invasive devices were significantly associated with acquisition of A. baumannii on univariate analysis, while length of exposure to central venous catheters and assisted ventilation were the only independent risk factors after multi-variate analysis.

CONCLUSIONS

This XDR A. baumannii outbreak in an NICU was probably caused by intrahospital transfer of bacteria via a colonized neonate whose mother was admitted to the adult ICU. Strengthened infection control measures were necessary to control the outbreak.

Validation of intensive care unit-acquired infection surveillance in the Italian SPIN-UTI network

Validity is one of the most critical factors concerning surveillance of nosocomial infections (NIs). This article describes the first validation study of the Italian Nosocomial Infections Surveillance in Intensive Care Units (ICUs) project (SPIN-UTI) surveillance data. The objective was to validate infection data and thus to determine the sensitivity, specificity, and positive and negative predictive values of NI data reported on patients in the ICUs participating in the SPIN-UTI network. A validation study was performed at the end of the surveillance period. All medical records including all clinical and laboratory data were reviewed retrospectively by the trained physicians of the validation team and a positive predictive value (PPV), a negative predictive value (NPV), sensitivity and specificity were calculated. Eight ICUs (16.3%) were randomly chosen from all 49 SPIN-UTI ICUs for the validation study. In total, the validation team reviewed 832 patient charts (27.3% of the SPIN-UTI patients). The PPV was 83.5% and the NPV was 97.3%. The overall sensitivity was 82.3% and overall specificity was 97.2%. Over- and under-reporting of NIs were related to misinterpretation of the case definitions and deviations from the protocol despite previous training and instructions. The results of this study are useful to identify methodological problems within a surveillance system and have been used to plan retraining for surveillance personnel and to design and implement the second phase of the SPIN-UTI project.

Building a benchmark through active surveillance of intensive care unit-acquired infections: the Italian network SPIN-UTI

The Italian Nosocomial Infections Surveillance in Intensive Care Units (ICUs) (SPIN-UTI) project of the Italian Study Group of Hospital Hygiene (GISIO - SItI) was undertaken to ensure standardisation of definitions, data collection and reporting procedures using the Hospital in Europe Link for Infection Control through Surveillance (HELICS)-ICU benchmark. Before starting surveillance, participant ICUs met in order to involve the key stakeholders in the project through participation in planning. Four electronic data forms for web-based data collection were designed. The six-month patient-based prospective survey was undertaken from November 2006 to May 2007, preceded by a one-month surveillance pilot study to assess the overall feasibility of the programme and to determine the time needed and resources for participant hospitals. The SPIN-UTI project included 49 ICUs, 3053 patients with length of stay >2 days and 35 498 patient-days. The cumulative incidence of infections was 19.8 per 100 patients and the incidence density was 17.1 per 1000 patient-days. The most frequently encountered infection type was pneumonia, Pseudomonas aeruginosa being the most frequent infection-associated micro-organism, followed by Staphylococcus aureus and Acinetobacter baumannii. Site-specific infection rates for pneumonia, bloodstream infections, central venous catheter-related bloodstream infections and urinary tract infections, stratified according to patient risk factors, were below the 75th centile reported by the HELICS network benchmark. The SPIN-UTI project showed that introduction of ongoing surveillance should be possible in many Italian hospitals. The study provided the opportunity to participate in the HELICS project using benchmark data for comparison and for better understanding of factors influencing risks.

Alert surveillance of intensive care unit-acquired Acinetobacter infections in a Sicilian hospital

The epidemiological impact of Acinetobacter baumannii nosocomial infections in a Sicilian intensive care unit (ICU) was investigated to determine the Acinetobacter-specific infection rates, to estimate the preventable proportion of Acinetobacter infections, i.e., those resulting from cross-transmission, and to investigate the molecular epidemiology of antimicrobial resistance in Acinetobacter. The impact of Acinetobacter nosocomial infection in the ICU was determined to be 3.0 new cases per 100 admissions. Site-specific rates confirmed that ICU-acquired pneumonia was the most important infection type. The incidence rate, adjusted by the number of patient-days, was 3.3 infections/1000 patient-days. The estimated preventable proportion of A. baumannii nosocomial infections in the ICU was 66.7%. A class 1 integron, characterised by its gene cassette content, was present in all A. baumannii isolates of four different pulsed-field gel electrophoresis types, and was associated significantly with clones implicated in cross-transmission episodes. Furthermore, the same integron was detected in two genetically distinct isolates responsible for recurrent infection in the same patient, suggesting the occurrence of horizontal gene transfer in vivo. Even in an endemic setting with low infection rates, spread of A. baumannii was caused mainly by infection control shortcomings that require appropriate surveillance and control policies.

Nosocomial infections in heart surgery patients: active surveillance in two Italian hospitals

In Italy no nosocomial infection surveillance database has been established despite the fact that a decrease of nosocomial infection rates was one of the priorities of the Italian National Health Plan 1998--2000. Heart surgery operations are the most frequent high risk procedures in western countries. Active surveillance was performed at the heart surgery wards of two Italian hospitals (Rome and Catania, Southern Italy) in accordance with the methods described for the National Nosocomial Infections Surveillance (NNIS) System of the USA. In both hospitals surgical site infections (SSIs) were the most frequently encountered type of nosocomial infections, accounting for 57.2% in Rome and 50% in Catania, and SSI rates in coronary artery bypass grafts with both chest and donor site incisions, calculated by risk index equal to 1, were above the 90th percentile for the NNIS System. The urinary catheter-associated urinary tract infection (UTI) rate (5.8%) in Catania exceeded the 90th percentile for the NNIS System, while the device-associated UTI (1.6%), bloodstream (4.1%) and pneumonia (8.0%) rates, from the hospital in Rome, did not. All device utilization ratios were lower than the 10th percentile for the NNIS System. Our study demonstrated that the NNIS methodology is applicable to Italian hospitals, although with some limitations mainly regarding the minimal surveillance duration required for significant interhospital comparison, and highlighted the need of a national comparison of surveillance data as benchmark.

Non compliance to therapeutic prescriptions in paediatric patients: role of social communication

The aim of this pilot study was to identify prevalent non-compliance behaviour in paediatric antibiotic therapy and to investigate the possible role of its social correlates. Patients' parents were surveyed at two paediatric practices in Catania, Italy, using an interviewer-administered questionnaire. The two practices were chosen for their location, in two different urban areas, to represent different sets of parents in terms of social status. Anticipated suspension of prescribed antibiotic therapy was the most frequently encountered form of non-compliance, shown by 41.2% of the parents. After partitioning the sample by mothers' occupational status--housewives versus working women--anticipated suspension revealed a positive association with educational level among the former group and a negative one, although not statistically significant, among the latter. Exposition to mass media messages about bacterial antibiotic resistance appeared to be a key intervening variable in interpreting these results, especially among more educated parents. Non-compliance was also associated with perceived characteristics of doctor-parents communication, particularly, with parents' perceived understanding of prescribed therapy.

Clonal spread of Acinetobacter baumannii in a general intensive care unit

The epidemiological characterization of multiply resistant Acinetobacter baumannii isolates from a six-bed Intensive Care Unit (ICU) is described. Investigations for A. baumannii were performed in three subsequent surveillance studies. In the first study, surveillance cultures were taken from patients, health care personnel and the environment; in the second study surveillance cultures were taken at 0, 4, and 7 days from all patients admitted consecutively to the ward; and in the third study surveillance cultures were taken from patients, health care personnel and the environment. During the first study all four hospitalized patients were found to harbour A. baumannii. Hand cultures did not grow any A. baumannii when staff entered the ward from home, but 7 positive health care workers were identified out of 25 samples taken during work, and two cultures of environmental specimens grew A. baumannii. During the second study, 4 of 86 (4.6%) patients resulted colonized with A. baumannii. In the third epidemiological study, no A. baumannii was cultured from either patients, health care personnel or the environment. All isolates recovered from various patients or sources produced conserved macrorestriction Pulsed-Field Gel Electrophoresis (PFGE) patterns and showed the same antibiotic resistance; therefore, they can be considered indistinguishable. The same antibiotic resistance and macrorestriction patterns were observed in previously isolated A. baumannii strains in the ward during May 1997, suggesting the persistence of a single A. baumannii in the ICU. The present study confirms that molecular typing is an essential tool in the epidemiology and control of nosocomial infections, showing here the persistence of a single A. baumannii clone in the ICU. The origin of this strain remains unknown but, when basic infection control measures were reinforced, emphasizing the importance of hand antisepsis and judicious use of gloves, control of A. baumannii spread in the ward was achieved.

Burkholderia cepacia complex in cystic fibrosis and non-cystic fibrosis patients: identification of a cluster of epidemic lineages

This study was performed in order to compare Burkholderia cepacia complex strains from cystic fibrosis (CF) and non-CF patients at the genomovar, genetic and epidemiological levels. A total of 92 B. cepacia respiratory tract isolates were obtained from patients attending the following CF centres: Catania and Palermo, Sicily; Gualdo Tadino, Central Italy, and Milan, Northern Italy. A total of 23 B. cepacia isolates were obtained from blood, surgical wound, and intravenous catheter sources of patients without CF, hospitalized in Catania and Varese, Northern Italy. Genomovar status identification, clonality and genetic relatedness determination, antibiotic susceptibility pattern determination and electron microscopy were performed. Transmission of infection was shown in both CF and non-CF patients by identifying clonality of responsible strains. In total 13 clones were involved in cross-transmission episodes. No outbreak was described involving both CF and non-CF patients. The present study indicates the existence of a distinct cluster of strains responsible for epidemics in CF and non-CF patients, based on their genetic relatedness, distinct from strains associated with no or negligible transmissibility. This result suggests that transmissibility is not only associated with a specific genomovar in CF patients, but also with a group of genetically related lineages in CF and non-CF patients. A key role is shown for both segregation measures and careful surveillance of infection, based on selective culture, molecular identification and epidemiological characterization of individual isolates.

Burkholderia cepacia complex infection in Italian patients with cystic fibrosis: prevalence, epidemiology, and genomovar status

The prevalence, epidemiology, and genomovar status of Burkholderia cepacia complex strains recovered from Italian cystic fibrosis (CF) patients were investigated using genetic typing and species identification methods. Four CF treatment centers were examined: two in Sicily, one in central Italy, and one in northern Italy. B. cepacia complex bacteria were isolated from 59 out of 683 CF patients attending these centers (8.6%). For the two geographically related treatment centers in Sicily, there was a high incidence of infection caused by a single epidemic clone possessing the cblA gene and belonging to B. cepacia genomovar III, recA group III-A, closely related to the major North America-United Kingdom clone, ET12; instability of the cblA sequence was also demonstrated for clonal isolates. In summary, of all the strains of B. cepacia encountered in the Italian CF population, the genomovar III, recA group III-A strains were the most prevalent and transmissible. However, patient-to-patient spread was also observed with several other genomovars, including strains of novel taxonomic status within the B. cepacia complex. A combination of genetic identification and molecular typing analysis is recommended to fully define specific risks posed by the genomovar status of strains within the B. cepacia complex.

Molecular epidemiology of Pseudomonas aeruginosa from cystic fibrosis in Sicily: genome macrorestriction analysis and rapid PCR-ribotyping

This study addresses the epidemiologic relatedness of a collection of Pseudomonas aeruginosa isolates from cystic fibrosis patients attending the Pediatric Clinic, Catania, Sicily. Genome macrorestriction analysis after pulsed field gel electrophoresis (PFGE) was used to characterise all strains. Furthermore, a rapid typing procedure, developed in this study, based on polymerase chain reaction amplified ribosomal DNA spacer polymorphisms (PCR-ribotyping), straight from bacterial cultures, was used. On the basis of macrorestriction analysis after PFGE, persistence of infection was shown in all patients; two cross-transmission episodes were identified in the nosocomial as well as in the familiar environment. PCR-ribotyping proved to be useful for a DNA-based identification test, suitable for screening purposes. The rapid amplification protocol here tested is proposed to evaluate the discriminatory power of other specific target sequences in PCR-based typing assays, for epidemiologic purposes.

Molecular epidemiology of enterococci with high-level resistance to aminoglycosides

DNA-based methodologies are considerably more powerful than other phenotype-based typing systems, providing a finer level of epidemiological discrimination, differentiating both closely and distantly related independent isolates that otherwise may appear as identical. In this study, plasmid analysis and pulsed-field gel electrophoresis were used to compare 28 isolates of Enterococci (respectively 13 strains of Enterococcus faecalis and 15 strains of Enterococcus faecium) with high-level resistance to aminoglycosides, isolated in Catania (Italy). Plasmid profile analysis resolved 20 different patterns among 24 plasmid harboring strains; many isolates showed one or two plasmids of the same size, but different plasmid content. Analysis of the PFGE-based RFLP patterns after SmaI digestion of genomic DNA resolved 26 different clones from 28 isolates: particularly, it resolved two different clones from three isolates showing identical plasmid profiles, and it identified as a single clone two isolates exhibiting different plasmid profiles. Thus, on the basis of our PFGE-based RFLP analysis data, we concluded that all the strains included in the study were genetically unrelated with two exceptions.

Molecular epidemiology of antibiotic resistance

Molecular typing methods based on the analysis of the genetic structure of bacteria, are used to address many different problems such as the study of genomic organisation and evolution, the identification of patterns of infection, the identification of sources of transmission, the epidemiological surveillance of infectious diseases and for investigations into outbreaks. Of particular interest is the application of these techniques for acquiring information on the spread of micro-organisms that have become resistant to many clinically important antibiotics. The emergence of antibiotic resistance is one of the most dangerous phenomena of the last 20 years and knowledge of the mechanisms of resistant-gene exchange means fully understanding their spread into all environments. Studies on the molecular epidemiology of antibiotic-resistance in micro-organisms should make it easier to distinguish clonality with respect to horizontal transfer of the determinants of resistance.