Aurora Aleo

Genetic relatedness among isolates of Shigella sonnei carrying class 2 integrons in Tehran, Iran, 2002–2003

BackgroundShigella spp. are major cause of diarrhoeal disease in both developing and developed countries. Shigella sonnei is the serogroup of Shigella most frequently responsible for sporadic and epidemic enteritis in developed countries. In recent years the emergence and spread of S. sonnei biotype g carrying class 2 integron have been frequently reported in many countries. Recently, S. sonnei has been reported as the prevalent serogroup of Shigella in Iran.The present study was carried out to investigate phenotypic and genetic characteristics of Shigella sonnei isolates identified in the years 2002 and 2003 in Tehran, Iran.MethodsBiotyping, drug susceptibility testing, pulsed field gel electrophoresis (PFGE) and analysis of class 2 integrons have been carried out on 60 S. sonnei isolates, including 57 sporadic isolates from paediatric cases of shigellosis occurring in 2002 and 2003, two sporadic isolates recovered in 1984 and the ATCC 9290 strain.ResultsBiotype g and resistance to streptomycin, sulfamethoxazole-trimethoprim and tetracycline were exhibited by 54 of the 57 recent isolates. Of the 54 biotype g isolates, 28 exhibited a class 2 integron of 2161 bp, and 24 a class 2 integron of 1371 bp, respectively. Class 2 integrons were not detected in four isolates only, including the two endemic isolates recovered in 1984 and two strains from recent sporadic cases. PFGE divided the strains into eight pulsotypes labeled A to H, three major pulsotypes – A to C – including the large majority of the recent sporadic S. sonnei isolates. Pulsotypes A and C were the most prevalent groups, accounting for 41.6% and 35.0%, respectively, of the isolates under study.ConclusionThe results suggest that biotype g, class 2 integron carrying S. sonnei are prevalent in our geographic area. S. sonnei isolated in the years 2002 and 2003 could be attributed to a few predominant clusters including, respectively, strains with pulsotypes B and C carrying a 2161 bp class 2 integron, and those having pulsotype A and a 1371 bp class 2 integron. A few epidemic clones are responsible for the apparently endemic occurrence of shigellosis in Tehran, Iran.

Characterization of Listeria monocytogenes Isolates from Human Listeriosis Cases in Italy

ABSTRACT The objective of this study was to characterize by serotyping, pulsed-field gel electrophoresis (PFGE), and PCR amplification of virulence genes and markers of epidemic clones I, II, and III (ECI, ECII, and ECIII) 54 human isolates from apparently sporadic cases of infection occurring in the Lombardy region and in the province of Florence, Tuscany, Italy, in the years 1996 to 2007. Listeria monocytogenes isolates were provided by the clinical microbiology laboratories of the Lombardy region and the “Careggi” Hospital of Florence, Tuscany, Italy. Serotyping, PFGE after digestion with the AscI and ApaI enzymes, and PCR amplification for the inlA, inlC, and inlJ genes and ECI, ECII, and ECIII markers were performed according to procedures described previously. Twenty-five (46.3%) L. monocytogenes isolates were assigned to serotype 1/2a, 23 (42.6%) to serotype 4b, and 6 (11.1%) to serotype 1/2b. Thirty-one AscI pulsotypes were recognized among the 54 human isolates. Eleven molecular subtype clusters, of which eight included indistinguishable pulsotypes and three included closely related pulsotypes, were shared by two to seven isolates. Fifteen isolates exhibited unique AscI pulsotypes. Three groups of clustered isolates and two apparently sporadic isolates generated EC amplicons. All strains tested positive for the inlA, inlC, and inlJ genes. Based on the results of serotyping and molecular typing, there were 11 occasions when L. monocytogenes strains with the same subtype were isolated from more than one listeriosis case. A total of 39 out of 54 isolates (72.2%) were attributed to molecular subtype clusters. The results of the study suggest that routine subtyping of L. monocytogenes strains from human listeriosis cases could allow more-timely detection of outbreaks possibly caused by food-borne isolates from a common source and could lead to control of ongoing food exposure, thus preventing the occurrence of more cases.

An Update of the Evolving Epidemic of blaKPC Carrying Klebsiella pneumoniae in Sicily, Italy, 2014: Emergence of Multiple Non-ST258 Clones

Background In Italy, Klebsiella pneumoniae carbapenemase producing K. pneumoniae (KPC-Kp) strains are highly endemic and KPC producing CC258 is reported as the widely predominating clone. In Palermo, Italy, previous reports have confirmed this pattern. However, recent preliminary findings suggest that an epidemiological change is likely ongoing towards a polyclonal KPC-Kp spread. Here we present the results of molecular typing of 94 carbapenem non susceptible K. pneumoniae isolates detected during 2014 in the three different hospitals in Palermo, Italy. Methods and Results Ninety-four consecutive, non replicate carbapenem non susceptible isolates were identified in the three largest acute general hospitals in Palermo, Italy, in the six-month period March-August 2014. They were characterized by PCR for β-lactam, aminoglycoside and plasmid mediated fluoroquinolone resistance genetic determinants. The mgrB gene of the colistin resistant isolates was amplified and sequenced. Clonality was assessed by pulsed field gel electrophoresis and multilocus sequence typing. Eight non-CC258 sequence types (STs) were identified accounting for 60% of isolates. In particular, ST307 and ST273 accounted for 29% and 18% of isolates. CC258 isolates were more frequently susceptible to gentamicin and non-CC258 isolates to amikacin. Colistin non susceptibility was found in 42% of isolates. Modifications of mgrB were found in 32 isolates. Conclusions Concurrent clonal expansion of some STs and lateral transmission of genetic resistance determinants are likely producing a thorough change of the KPC-Kp epidemiology in Palermo, Italy. In our setting mgrB inactivation proved to substantially contribute to colistin resistance. Our findings suggest the need to continuously monitor the KPC-Kp epidemiology and to assess by a nationwide survey the possible shifting towards a polyclonal epidemic.

Enhanced surveillance of invasive listeriosis in the Lombardy region, Italy, in the years 2006-2010 reveals major clones and an increase in serotype 1/2a

BackgroundInvasive listeriosis is a rare, life-threatening foodborne disease. Lombardy, an Italian region accounting for 16% of the total population, reported 55% of all listeriosis cases in the years 2006-2010. The aim of our study was to provide a snapshot of listeriosis epidemiology in this region after the implementation of a voluntary laboratory-based surveillance system.MethodsWe characterized by serotyping, pulsed-field gel electrophoresis, multilocus sequence typing and detection of epidemic clone markers, 134 isolates from 132 listeriosis cases, including 15 pregnancy-related cases, occurring in the years 2006-2010 in Lombardy. Demographic and clinical characteristics of cases have also been described.ResultsThe mean age of non pregnancy-associated cases was 64.7 years, with 55.9% of cases being older than 65 years. Cases having no underlying medical conditions accounted for 11.6%. The all-cause fatality rate of 83 cases with a known survival outcome was 25.3%.Serotypes 1/2a and 4b comprised 52.2% and 38.8% of isolates, respectively. Seventy-three AscI pulsotypes and 25 sequence types assigned to 23 clonal complexes were recognized. Moreover, 53 (39.5%) isolates tested positive for the epidemic clone markers. Twelve molecular subtype clusters including at least three isolates were detected, with cluster 11 (1/2a/ST38) including 31 isolates identified during the entire study period. No outbreaks were notified to public health authorities during this period.ConclusionsThe findings of our study proved that epidemiology of listeriosis in Lombardy is characterized by a high prevalence of major clones and the increasing role of serotype 1/2a. Molecular subtyping is an essential tool in the epidemiology and surveillance of listeriosis. Rapid molecular cluster detection could alert about putative outbreaks, thus increasing the chance of detecting and inactivating routes of transmission.

Serotypes, Antibiotic Resistance, and Class 1 Integrons in Salmonella Isolates from Pediatric Cases of Enteritis in Tehran, Iran

The present study was conducted to investigate serotype distribution, antimicrobial resistance patterns, carriage of class 1 integron, and clonality of Salmonella strains isolated from patients aged 0-12 years in Tehran, Iran, during 2007-2008. A total of 139 Salmonella isolates were studied. Salmonella serotypes Enteritidis, Infantis, and Typhimurium included 84.9% of isolates, Enteritidis accounting for 41.7%. The most prevalent resistances were to doxycycline (64.7%), nalidixic acid (61.2%), tetracycline (51.8%), and streptomycin (42.8%). Fifty-three (38.1%) isolates contained class 1 integron. Eight different gene cassettes were identified, aadA1 being the most frequently encountered. Pulsed-field gel electrophoresis showed that integron-positive Salmonella strains belonging to serotypes Infantis, Enteritidis, and Typhimurium were attributed to two, three, and five different pulsotypes, respectively. The findings indicated that the distribution and drug resistance pattern of most prevalent Salmonella serotypes were broadly similar to that reported globally from human isolates. Presence of class 1 integrons was common among Salmonella serotypes in Tehran, Iran. Concurrent clonal expansion and horizontal transmission events seem to contribute to increase in drug resistance prevalence among Salmonella serotypes.

Outbreak of colonizations by extended-spectrum β-lactamase-producing Escherichia coli sequence type 131 in a neonatal intensive care unit, Italy

BackgroundExtended spectrum β-lactamases (ESBLs) often associated with resistance to aminoglycosides and fluoroquinolones have recently emerged in community-associated Escherichia coli. The worldwide clonal dissemination of E. coli sequence type (ST)131 is playing a prominent role.We describe an outbreak of colonizations by ESBL-producing E. coli (ESBL-E. coli) in the neonatal intensive care unit (NICU) of the University Hospital, Palermo, Italy.MethodsAn epidemiological investigation was conducted with the support of molecular typing. All children admitted to the NICU and colonized by ESBL-E. coli between January and June 2012, were included in the study. Cases were defined as infants colonized by E. coli resistant to third generation cephalosporins and fluoroquinolones. A case–control study was also performed to identify possible risk factors.ResultsDuring the outbreak period, 15 infants were found to be colonized by ESBL-E. coli. The epidemic strain demonstrated continuous transmission throughout the outbreak period. Case–control study identified a lower birth weight as the only risk factor for colonization. The strain belonged to the sequence-type 131 community-associated clone. Transmission control interventions, including contact precautions and cohorting, restriction of the new admissions, sanitization of surfaces and equipment and targeted training sessions of the NICU staff, were successful in interrupting the outbreak.ConclusionsAlthough invasive infections did not develop in any of the 15 colonized neonates, our report highlights the need to strictly monitor the spill in the NICU setting of multidrug resistant community-associated organisms. Our findings confirm also the role of active surveillance in detecting the silent spread of ESBL-producing Gram negatives in a critical healthcare setting and trigging the implementation of infection control measures. As β-lactam and fluoroquinolone resistant E. coli strains are increasingly spreading in the community, this event could become a more serious challenge.

Epidemic spread of ST1-MRSA-IVa in a neonatal intensive care unit, Italy

BackgroundCommunity-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has recently emerged as an important pathogen in neonatal intensive care units (NICUs). The purposes of this study were to characterize methicillin-resistant isolates from an outbreak in a NICU, to examine the genetic traits and clonality of CA-MRSA, and to review the characteristics and outcomes of the neonatal cases and investigate the routes of entry and transmission of the MRSA outbreak strain in the NICU under study.MethodsThe study NICU practiced an active surveillance program for multidrug-resistant organisms, including weekly cultures for detection of MRSA from nasal swabs among all the admitted neonates. All first isolates from surveillance cultures and all clinical isolates were submitted for susceptibility testing and genotyping. Data from each infant’s medical records were prospectively included in a database, and the clinical features and outcomes of the colonized/infected infants were assessed.ResultsA total of 14 infants were colonized or infected by a strain of ST1-MRSA-IVa between April and August 2011. The CA-MRSA strain appeared to have been introduced to the NICU by an infected infant transferred from another hospital. The outbreak was successfully contained by multifaceted infection control interventions.ConclusionsThe results of this study confirm that NICU is a healthcare setting with a critical permeability to CA-MRSA. Active surveillance including molecular typing can help to detect and monitor the spread of antimicrobial drug-resistant organisms, and thus trigger timely control interventions.

Characterization of the First Extended-Spectrum β-Lactamase–Producing Nontyphoidal Salmonella Strains Isolated in Tehran, Iran

The infections caused by Salmonella remain a significant public health problem throughout the world. beta-Lactams and fluoroquinolones are generally used to treat invasive Salmonella infections, but emergence and spread of antibiotic-resistant strains are being increasingly notified in many countries. In particular, detection of extended-spectrum beta-lactamases (ESBLs) in Salmonella spp. is a newly emerging threat worldwide. This study was carried out to characterize beta-lactamase-producing Salmonella strains identified in Tehran, Iran. Over the 2-year period from 2007 to 2008, 6 of 136 Salmonella isolates recovered from pediatrics patients, including three Salmonella enterica serotypes Enteritidis (S. Enteritidis) and three S. Infantis, showed an ESBL-positive phenotype. Polymerase chain reaction and sequencing were used to identify the genetic determinants responsible for ESBL phenotypes. The Salmonella isolates were also compared by pulsed-field gel electrophoresis. All ESBL-producing strains, but one, carried the bla(CTX-M-15) gene. Moreover, three of four strains that proved to be positive for a bla(TEM) gene were producing a TEM-1 beta-lactamase. Two strains of S. Infantis tested positive for a previously unidentified CTX-M and TEM ESBL, respectively. All ESBL-producing strains carried the insertion sequence ISEcp1 gene. Except for one strain of serotype Infantis, all strains were able to transfer the ESBL determinants by conjugation. Distinct, but closely related, pulsed-field gel electrophoresis patterns were observed among the strains belonging to both serotypes. This study reports for the first time the emergence and characterization of ESBL-producing S. Enteritidis and Infantis strains in Iran.

OXA-163-Producing Klebsiella pneumoniae in Cairo, Egypt, in 2009 and 2010

ABSTRACT Two genetically unrelated OXA-163-carrying Klebsiella pneumoniae strains were identified from two infection cases in June 2009 and May 2010 in Cairo, Egypt. OXA-163-producing Enterobacteriaceae had been previously reported in Argentina only. Both patients had no history of travel abroad. The emergence of this newly recognized OXA-48-related β-lactamase able to hydrolyze cephalosporins and carbapenems is especially worrying in a geographic area where OXA-48 is endemic and effective surveillance for antibiotic resistance is largely unaffordable.

Molecular Epidemiological Survey of Citrobacter freundii Misidentified as Cronobacter spp. (Enterobacter sakazakii) and Enterobacter hormaechei Isolated from Powdered Infant Milk Formula

A total of 75 powdered infant milk formula (PIF) samples collected from pharmacies and drugstores in Western Sicily, Italy, and representative of 12 different brands were analyzed in this study to evaluate their microbiological quality. According to the U.S. Food and Drug Administration protocol, 32 samples out of 75 were contaminated by enterobacteria. Commercial biochemical API(r) 20E-system identification method indicated that six PIF samples were presumptively contaminated by Cronobacter spp., but further characterization by alpha-glucosidase based polymerase chain reaction (PCR) assay identification strongly suggested that these strains did not belong to the genus Cronobacter. Phylogenetic analysis of partial 16S rRNA (rrs) sequences combined with the results of biochemical tests allowed to identify the six strains as Citrobacter freundii. Similarly, rrs sequence analysis identified as Enterobacter hormaechei 23 strains originally ascribed to Enterobacter cloacae by the API 20E system. Characterization of C. freundii and E. hormaechei PIF isolates by the DiversiLab(r) repetitive sequence-based PCR (rep-PCR) typing method revealed a variety of amplification patterns, but the recovery of the same rep-PCR genotype in several products might indicate a special adaptation of genetic clones to this food or cross-contamination through common ingredients. Antibiotic-resistance profiles were also determined, but none of the strains tested was resistant to third-generation cephalosporins or fluoroquinolones and extended-spectrum beta-lactamase activity was not detected. Our results confirm that E. hormaechei contamination of PIF is widespread, thus making it a cause for concern. Similarly to what was demonstrated for E. hormaechei, we suggest that C. freundii also may be an under-reported cause of bacterial infection, especially in high-risk neonates, due to misidentification.