Unique Pulsed-field Gel Electrophoresis Patterns Research Articles

Epidemiological Analysis of Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae Outbreak in a Neonatal Clinic in Poland.

Klebsiella pneumoniae is one of the most common etiological agents isolated from epidemic outbreaks in neonatal wards. We describe how an extended-spectrum β-lactamase-producing K. pneumoniae (ESBL-KP) outbreak in a neonatal ward was extinguished. During the outbreak, which lasted over two months, 26 neonates were tested for K. pneumoniae, and 42 environmental swabs were taken. Drug susceptibility was determined for the isolated strains, and their virulence and phylogenetic similarity were checked. ESBL-KP colonization was confirmed in 18 neonates, and six were also confirmed to be infected. All strains isolated from patients represented one clonal type, K. pneumoniae. One strain isolated from an environmental source was determined to be a unique pulsed-field gel electrophoresis pattern. Gestational age and Apgar score were assessed as statistically significant for neonates with ESBL-KP infection. The epidemiological measures taken have been successful, and no further cases appeared. Immediate tightening of hospital hygiene rules, screening of all hospitalized neonates, and cohorting ESBL-KP-positive patients proved effective in controlling and ending the outbreak. The lack of ESBL-KP in the environment suggests that the outbreak was transmitted by colonized hospital staff. This theory could be confirmed by introducing mandatory screening for medical personnel.

Molecular Epidemiology and Drug Resistance Pattern of Carbapenem-Resistant Klebsiella pneumoniae Isolates from Iran.

The emergence and dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates and their involvement in several nosocomial outbreaks are of high concern. This study was conducted to investigate the genetic relatedness and molecular determinants of carbapenem resistance in 100 CRKP isolates. Susceptibility to carbapenems as well as other antibiotics was determined by using disk diffusion method. The Modified Hodge test was performed for detection of carbapenemase production. The minimum inhibitory concentrations of selected antibiotics were determined by broth microdilution method. The presence of blaOXA-48, blaKPC, blaNDM, and blaVIM carbapenemase genes was examined by PCR, and clonal relatedness of CRKP isolates was investigated by pulsed-field gel electrophoresis (PFGE) analysis. blaOXA-48 was the most frequent carbapenemase gene (72%), followed by blaNDM (31%). None of the isolates harbored blaKPC and blaVIM genes. PFGE separated the majority of isolates into 10 clusters, including the major clusters A and B, carrying blaOXA-48, and clusters C and D, carrying blaNDM, and 4 isolates had a unique PFGE pattern. An increased rate of colistin resistance (50%) was detected among the isolates. Tigecycline was found to be the most active agent against CRKP isolates. Our results revealed that high prevalence of blaOXA-48 and blaNDM carbapenamses and resistance to colistin are alarming threats, necessitating an immediate action to prevent the spread of carbapenem-colistin-resistant K. pneumoniae isolates in Iran.

Molecular Characterization of Salmonella from Beef Carcasses and Fecal Samples from an Integrated Feedlot and Abattoir in Mexico

Nontyphoid Salmonella strains are some of the leading causes of foodborne illnesses worldwide; however, there is very limited information on the presence and characteristics of Salmonella in the food production chain in developing countries. In this study, pulsed-field gel electrophoresis (PFGE) was used for molecular subtyping and for monitoring the ecology and transmission of Salmonella isolates in a slaughter facility in Mexico in an attempt to determine specific steps that need to be improved to reduce Salmonella contamination in beef carcasses. A total of 94 isolates from a Salmonella stock culture collection originally obtained from a single vertically integrated feedlot and beef abattoir in Mexico were analyzed. A total of 26 unique PFGE patterns were identified, 38.5% of them corresponding to a single serotype. High concordance (88.4%) was found between serotype and PFGE banding subtype. Salmonella Kentucky and Salmonella Give were the most clonal subtypes in this study, and Salmonella Muenster was the most diverse, with 11 banding patterns identified. A total of 73.7, 70.6, and 85.7% of the PFGE subtypes identified from preevisceration, precooler, and chilled carcasses, respectively, were identified only at those specific points and not at any previous or subsequent steps of the slaughter process, suggesting that each step is in itself a source of Salmonella contamination. Salmonella Mbandaka was more likely to be recovered from feces than from any of the steps of the slaughter process. The genetic diversity and distribution of PFGE subtypes in the processing facility highlight the need to implement antimicrobial interventions and improve sanitation procedures at various points to avoid further Salmonella dissemination into the meat supply.

Clostridium difficile Molecular Epidemiology in a Prospective Cohort of Canadian Children Compared with Cases of C. difficile Infection

Background Clostridium difficile is a notorious nosocomial pathogen, but little is known regarding the colonization commonly observed in children. It is suspected that C. difficile carriage in infants is a reservoir for toxigenic strains. To test this hypothesis, we sought to determine the genetic relatedness between a prospective cohort of C. difficile toxin gene positive healthy children and those with acute gastroenteritis (AGE) and strains identified in adult and pediatric C. difficile infection (CDI) cases from Alberta, Canada. Additionally, we compared C. difficile toxin production in healthy and AGE children.Methods C. difficile was cultured from 97 hospitalized CDI cases (n = 79 adult; n = 18 pediatric) from stool samples tested positive for toxigenic C. difficile by C.DIFF QUIK CHEK COMPLETE® enzyme immunoassay (EIA) in 2015 and samples tested positive for toxin genes by the Luminex xTAG® Gastrointestinal Pathogen Panel from a prospective cohort of 59 children with AGE seeking care at the emergency department and 17 healthy children attending public health clinics. Isolates were then characterized by PCR-ribotyping, pulsed-field gel electrophoresis (PFGE), PCR of the tcdA, tcdB, tcdC, and cdtB genes and C. difficile toxigenicity by EIA for a subset of 14 healthy and 45 AGE children.ResultsRibotype 106 was predominant among all pediatric isolates (n = 21, 27.6% AGE and healthy children; n = 5, 27.8% pediatric CDI) and ribotype 027 in adult CDIs (n = 35, 44.3%). Eighteen ribotypes were shared between children and CDI cases (n = 134, 77.5%). Sixteen unique ribotype and PFGE patterns (n = 84, 48.6%) were identified in two or more cohorts. Similar toxin gene profiles were observed across the three cohorts, but adult CDI isolates had a higher proportion of binary toxin positive isolates (n = 42, 53.2%) compared with children (n = 3, 3.95%) and pediatric CDI (n = 0). C. difficile toxigenicity was similar (P = 0.23) amongst the subset of healthy (n = 6, 42.9%) and AGE (n = 28, 62.2%) children.ConclusionProduction of C. difficile toxins in children was not significantly associated with symptoms of AGE. C. difficile strains found in children were similar to those from CDI cases; especially pediatric cases. This suggests that strains might be shared, but the development of CDI may be related to factors other than C. difficile strain type.Disclosures All authors: No reported disclosures.

Characterizing Salmonella Contamination in Two Rendering Processing Plants

A microbiological investigation on Salmonella contamination was conducted in two U.S. rendering plants to investigate the potential cross-contamination of Salmonella in the rendering processing environment. Sampling locations were predetermined at the areas where Salmonella contamination may potentially occur, including raw materials receiving, crax (rendered materials before grinding process) grinding, and finished meal loading-out areas. Salmonella was either enumerated directly on xylose lysine Tergitol 4 agar plates or enriched in Rappaport-Vassiliadis and tetrathionate broths. The presumptive Salmonella isolates were confirmed using CHROMagar plating and latex agglutination testing and then characterized using pulsed-field gel electrophoresis, serotyping, and biofilm-forming determination. Among 108 samples analyzed, 79 (73%) samples were Salmonella positive after enrichment. Selected Salmonella isolates (n = 65) were assigned to 31 unique pulsed-field gel electrophoresis patterns, with 16 Salmonella serotypes, including Typhimurium and Mbandaka, identified as predominant serotypes and 10 Salmonella strains determined as strong biofilm formers. Our results indicated that the raw materials receiving area was the primary source of Salmonella and that the surfaces surrounding crax grinding and finished meal loading-out areas harbor Salmonella in biofilms that may recontaminate the finished meals. The same Salmonella serotypes found in both raw materials receiving and the finished meal loading-out areas suggested a potential of cross-contamination between different areas in the rendering processing environment.

Molecular Characterization of Carbapenemase-Nonproducing Clinical Isolates of Escherichia coli (from a Thai University Hospital) with Reduced Carbapenem Susceptibility.

Twelve nonreplicate carbapenemase-negative ertapenem (ETP)-nonsusceptible (CNENS) Escherichia coli isolates obtained at a Thai university hospital between 2010 and 2014 were characterized and compared with 2 carbapenemase-producing E. coli isolates from the same hospital. Eight unique pulsed-field gel electrophoresis patterns were obtained. All the isolates produced CTX-M-15 β-lactamase and 2 either coexpressed CMY-2 cephalosporinase or showed increased efflux pump activity. Amino acid sequence analysis revealed that an OmpF defect (in 7 isolates) due to mutations generating truncated proteins or an IS1 insertion was more prevalent than a defect in OmpC was (no truncated proteins detected). Seven out of 10 isolates possessing OmpC variants with any OmpF defect were weakly ETP-resistant (minimum inhibitory concentrations [MICs] of 1-4 μg/mL) and imipenem (IPM)- and meropenem (MEM)-susceptible (MICs 0.125-0.5 μg/mL). Two isolates with ompC PCR-negative results and an OmpF defect showed higher carbapenem MICs (8-32, 1-8, and 1-4 μg/mL for ETP, IPM, and MEM, respectively) with the highest MICs associated with the additional efflux pump activity. Both carbapenemase producers possessing CTX-M-15 and a porin background identical to that in the CNENS isolates showed ETP, IPM, and MEM MICs of 128-256, 8, and 2-32 μg/mL, respectively. These findings suggest that a porin defect combined with CTX-M-15 production is the major mechanism of low carbapenem susceptibility among our CNENS isolates, which have potential to become strongly carbapenem-resistant because of additional carbapenemase or efflux pump activities.

Molecular and Phenotypic Characterization of Multidrug-Resistant Clones of Staphylococcus epidermidis in Iranian Hospitals: Clonal Relatedness to Healthcare-Associated Methicillin-Resistant Isolates in Northern Europe.

The aim of the study was to investigate the molecular epidemiology of Staphylococcus epidermidis in Iranian hospitals and to compare the genotypes with a previously characterized collection of >1,300 S. epidermidis isolates of nosocomial and community origin from Northern Europe, Australia, and USA. In total, 82 clinical S. epidermidis isolates from three Iranian hospitals were examined by multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome mec (SCCmec) typing. In addition, antimicrobial susceptibility, the presence of the ica operon, and the predilection to biofilm formation were assessed. Three predominant PFGE clones were found. The PFGE patterns of the most common sequence type (PFGE type 040-ST2) showed 80% similarity to multidrug-resistant S. epidermidis (MDRSE) clinical isolates from eight hospitals in Northern Europe. The second most common (PFGE 024-ST22) showed an unique PFGE pattern, whereas the third most predominant genotype (PFGE 011-ST5) proved indistinguishable to the PFGE Co-ST5 identified in five hospitals in Northern Europe. In conclusion, the study documented the dissemination of three MDRSE clones within and between hospitals in Iran and revealed an intercontinental spread of two clonal multidrug-resistant lineages (ST2 and ST5) in the hospital environment. Isolates of the predominant clones were significantly more frequently associated with multidrug-resistance and biofilm formation compared to nonclonal isolates. Further studies are needed to explore and characterize the genetic traits that enable these successful MDRSE clones to persist and disseminate worldwide in the healthcare settings.

KPC-Producing Klebsiella pneumoniae Isolates in Croatia: A Nationwide Survey.

In the last few years, Klebsiella pneumoniae strains producing K. pneumoniae carbapenemase (KPC) enzymes have emerged as important multidrug-resistant pathogens in hospitalized patients. This report describes KPC-producing isolates collected through the Croatian antimicrobial resistance surveillance program in the early stage of their dissemination in Croatia. Forty-eight KPC-producing K. pneumoniae isolates, collected during a period from February 2011 to August 2013, were analyzed in this study. Antimicrobial susceptibility profiles were determined using disk diffusion and E-test. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used for epidemiological analysis. Identification of β-lactamase genes and associated antibiotic resistance mechanisms was performed by polymerase chain reaction and positive products were sequenced. Localization of blaKPC was investigated by S1 PFGE and Southern hybridization. Of 40 participating centers in Croatia, KPC isolates were recorded in 9 of them. They all had multidrug-resistant phenotype, but showed varying levels of resistance to carbapenems. All isolates displayed ST258, and PFGE showed that all but one were closely related. All isolates harbored blaKPC-2. Isolate with a unique PFGE pattern produced TEM-1, while others produced TEM-116. All isolates harbored blaSHV-11, but were negative for blaCTX-M and blaAmpC genes. All isolates contain one KPC-harboring plasmid, ranging in size from ∼60 to ∼210 kb, characterized as FIIs and IncR. This report describes that the early stage of KPC-producing K. pneumoniae dissemination in Croatia is associated with a prolific PFGE type belonging to ST258. So far, the spread of an outbreak strain is limited to the northwest region of the country.

Carbapenem non-susceptible enterobacteriaceae in Quebec, Canada: results of a laboratory surveillance program (2010-2012).

The emergence and spread of carbapenemase-producing Enterobacteriaceae (CPE) represent a major public health concern because these bacteria are usually extensively resistant to most antibiotics. In order to evaluate their dissemination in Quebec, a surveillance program was introduced in 2010. We report the molecular and epidemiological profiles of CPE isolates collected. Between August 2010 and December 2012, a total of 742 non-duplicate isolates non-susceptible to carbapenems were analysed. AmpC β-lactamase and metallo-β-lactamase production were detected by Etest and carbapenemase production by the modified Hodge test (MHT). Antibiotic susceptibility profiles were determined using broth microdilution or Etest. Clonality of Klebsiella pneumoniae carbapenemase (KPC) strains was analyzed by pulsed-field gel electrophoresis (PFGE). The presence of genes encoding carbapenemases as well as other β-lactamases was detected using PCR. Of the 742 isolates tested, 169 (22.8%) were CPE. Of these 169 isolates, 151 (89.3%) harboured a bla KPC gene while the remaining isolates carried bla SME (n = 9), bla OXA-48 (n = 5), bla NDM (n = 3), and bla NMC (n = 1) genes. Among the 93 KPC strains presenting with a unique pattern (unique PFGE pattern and/or unique antibiotics susceptibility profile), 99% were resistant to ertapenem, 95% to imipenem, 87% to meropenem, 97% to aztreonam, 31% to colistin and 2% to tigecycline. In 19 patients, 2 to 5 KPC strains from different species or with a different PFGE pattern were isolated. CPE strains were present in the province of Quebec with the majority of strains harbouring KPC. Alternately, SME, OXA-48 and NMC containing strains were rarely found.

Multilocus Sequence Typing Scheme versus Pulsed-Field Gel Electrophoresis for Typing Mycobacterium abscessus Isolates

Outbreaks of infections by rapidly growing mycobacteria following invasive procedures, such as ophthalmological, laparoscopic, arthroscopic, plastic, and cardiac surgeries, mesotherapy, and vaccination, have been detected in Brazil since 1998. Members of the Mycobacterium chelonae-Mycobacterium abscessus group have caused most of these outbreaks. As part of an epidemiological investigation, the isolates were typed by pulsed-field gel electrophoresis (PFGE). In this project, we performed a large-scale comparison of PFGE profiles with the results of a recently developed multilocus sequence typing (MLST) scheme for M. abscessus. Ninety-three isolates were analyzed, with 40 M. abscessus subsp. abscessus isolates, 47 M. abscessus subsp. bolletii isolates, and six isolates with no assigned subspecies. Forty-five isolates were obtained during five outbreaks, and 48 were sporadic isolates that were not associated with outbreaks. For MLST, seven housekeeping genes (argH, cya, glpK, gnd, murC, pta, and purH) were sequenced, and each isolate was assigned a sequence type (ST) from the combination of obtained alleles. The PFGE patterns of DraI-digested DNA were compared with the MLST results. All isolates were analyzable by both methods. Isolates from monoclonal outbreaks showed unique STs and indistinguishable or very similar PFGE patterns. Thirty-three STs and 49 unique PFGE patterns were identified among the 93 isolates. The Simpson's index of diversity values for MLST and PFGE were 0.69 and 0.93, respectively, for M. abscessus subsp. abscessus and 0.96 and 0.97, respectively, for M. abscessus subsp. bolletii. In conclusion, the MLST scheme showed 100% typeability and grouped monoclonal outbreak isolates in agreement with PFGE, but it was less discriminative than PFGE for M. abscessus.

Tracking Campylobacter contamination along a broiler chicken production chain from the farm level to retail in China

This study was conducted to determine the prevalence and distribution of Campylobacter species along a broiler production chain from farm to retail, and to evaluate the antimicrobial resistance profile of Campylobacter isolates. A total of 259 Campylobacter isolates (C. jejuni n=106, C. coli n=153) were isolated from broiler ceca samples (72.5%, 103/142), broiler carcasses (34.1%, 46/135), and retail broiler meat (31.3%, 40/128) samples collected in Shanghai, China. Minimal inhibitory concentrations of six antimicrobials were determined using the agar dilution method. High prevalence of resistance to ciprofloxacin (C. jejuni: 99.1%;C. coli: 100%) and tetracycline (C. jejuni: 100%;C. coli: 98.7%) was detected among the C. jejuni and C. coli isolates. The vast majority of C. coli were resistant to clindamycin (92.2%), gentamicin (95.4%), and erythromycin (94.1%), but only 25.5%, 53.8%, and 16.0% of C. jejuni exhibited resistance to these three antimicrobials, respectively. In contrast, the prevalence of florfenicol resistance in C. jejuni (37.7%) was significantly higher than that in C. coli (7.8%) (P<0.05). It is noteworthy that all Campylobacter isolates were resistant to one or more antimicrobials, and 71.7% of C. jejuni and 98.0% of C. coli isolates exhibited multi-drug resistance (resistant to three or more antimicrobials). Fifty-five C. jejuni and sixty C. coli isolates, selected from different production stages, species, and antimicrobial resistance patterns, were analyzed by pulsed field gel electrophoresis (PFGE), among which 15 unique PFGE patterns (PFGE patterns represented by a single strain) and 31 clusters (PFGE patterns represented by multiple strains) were detected. Furthermore, nearly all of the PFGE patterns of the Campylobacter strains isolated from retail broiler meats overlapped with those of the strains from ceca and slaughterhouse carcasses. Together, these findings revealed the high prevalence of Campylobacter species in a broiler chicken production chain, and the concerning situation of antimicrobial resistance in Campylobacter species. The findings also indicated that Campylobacter isolates from retail broiler meats were associated with fecal contamination in the slaughterhouse, underlying the need for improved measures for reducing carcass contamination in slaughter plants.

Molecular characterization of vancomycin-resistant enterococci in Serbia: Intensive care unit as the source

The purpose of this study was to evaluate the molecular relatedness of clinical isolates of vancomycin-resistant enterococci (VRE) collected from patients of the Clinic for Infectious and Tropical Diseases in Belgrade. Among 40 isolates available for the investigation, 36 were identified as Enterococcus faecium, whereas 2 were Enterococcus faecalis and Enterococcus raffinosus, respectively. Pulsed-field gel electrophoresis (PFGE) typing revealed 21 strain types, comprising 7 clusters which contained at least two isolates and 14 unique PFGE patterns. Although we searched for pathogenicity factor genes (gelE, cylB, asa1, efaAfs, esp, cpd, cob) in representatives of all macro-restriction patterns, they have been confirmed in only one clone of E. faecalis. Genes esp and hyl, commonly found in E. faecium, were yilded in 10 macro-restriction patterns of this species, and their presence could not be ascribed to clonally related strains (p = 0.05). All VRE isolates were multiresistant and positive for vanA gene. Twenty strains of VRE and 6 clusters obtained from Intensive care unit (ICU) are proof of intensive transmission of these microorganisms at this department. The results of this study suggest wide genotypic variability among the clinical VRE isolates, but also intrahospital dissemination of some of them.

Characterization of Escherichia coli O157:H7 Strains Isolated from Supershedding Cattle

Previous reports have indicated that a small proportion of cattle shedding high levels of Escherichia coli O157:H7 is the main source for transmission of this organism between animals. Cattle achieving a fecal shedding status of 10(4) CFU of E. coli O157:H7/gram or greater are now referred to as supershedders. The aim of this study was to investigate the contribution of E. coli O157:H7 strain type to supershedding and to determine if supershedding was restricted to a specific set of E. coli O157:H7 strains. Fecal swabs (n = 5,086) were collected from cattle at feedlots or during harvest. Supershedders constituted 2.0% of the bovine population tested. Supershedder isolates were characterized by pulsed-field gel electrophoresis (PFGE), phage typing, lineage-specific polymorphism assay (LSPA), Stx-associated bacteriophage insertion (SBI) site determination, and variant analysis of Shiga toxin, tir, and antiterminator Q genes. Isolates representing 52 unique PFGE patterns, 19 phage types, and 12 SBI clusters were obtained from supershedding cattle, indicating that there is no clustering to E. coli O157:H7 genotypes responsible for supershedding. While being isolated directly from cattle, this strain set tended to have higher frequencies of traits associated with human clinical isolates than previously collected bovine isolates with respect to lineage and tir allele, but not for SBI cluster and Q type. We conclude that no exclusive genotype was identified that was common to all supershedder isolates.

Dissemination of a pSCFS3-Like cfr -Carrying Plasmid in Staphylococcus aureus and Staphylococcus epidermidis Clinical Isolates Recovered from Hospitals in Ohio

Nineteen linezolid-resistant Staphylococcus epidermidis and two Staphylococcus aureus isolates recovered from two medical institutions in northeast Ohio and an S. aureus cfr index strain previously collected in the same facilities during the 2007 SENTRY Antimicrobial Surveillance Program were investigated for the genetic basis of oxazolidinone resistance and the location of cfr. S. aureus isolates were typed by pulsed-field gel electrophoresis (PFGE), spa typing, and multilocus sequence typing (MLST). The location of cfr was determined by Southern blotting and hybridization. Plasmid sequencing was performed using the 454 Life Sciences (Roche) GS-FLX DNA platform. The two S. aureus isolates showed unique PFGE patterns but were multilocus sequence type 5 (ST5) and spa type t002, whereas the S. aureus index strain was ST239 and t037. Southern blot and hybridization experiments showed that cfr was plasmid located and that the S. epidermidis isolates, one of the S. aureus isolates, and the S. aureus index strain shared an identical cfr-carrying plasmid (39.3 kb). Sequencing results confirmed these findings. A 10-kb fragment containing cfr showed the highest identity (99.9%) to a 9.5-kb fragment of plasmid pSCFS3 from a bovine Staphylococcus lentus isolate from Germany. In addition, these 39.3-kb plasmids from human S. epidermidis and S. aureus exhibited BglII restriction profiles very similar to that observed for plasmid pSCFS3. The cfr-carrying plasmid detected in the remaining S. aureus isolate (7.9 kb) was distinct and showed the highest identity to the chromosomal cfr integrate found in the chromosomal DNA of a Proteus vulgaris isolate from a pig in China.

First isolation of ciprofloxacin-resistant Salmonella enterica serovar Typhi in Taiwan

Typhoid fever is a major cause of disease burden in developing countries. The use of fluoroquinolones, once considered the drugs of choice, should be re-evaluated due to the emergence of quinolone-resistant Salmonella enterica serovar Typhi. In Taiwan, typhoid fever is rare but constitutes an important public health concern. In August 2011, two ciprofloxacin-resistant S. Typhi isolates were identified from one patient who had recently travelled to India. The two isolates together with four other ciprofloxacin-susceptible S. Typhi isolates were subjected for molecular investigation. Polymerase chain reaction (PCR) and sequencing were used to analyze the resistance mechanisms. Pulsed-field gel electrophoresis (PFGE) was performed to delineate the genetic relatedness among the isolates. In 2011, a total of 49 typhoid fever cases were reported to the Center for Disease Control in Taiwan, with a significant increase in indigenous cases in northern Taiwan from August to November. In the two S. Typhi isolates with complete resistance to ciprofloxacin [minimum inhibitory concentration (MIC) >32 μg/mL], multiple point mutations in the quinolone resistance-determining regions (QRDRs) of gyrA and parC genes were identified. A unique PFGE pattern was found in the resistant isolates and was different from the other representative susceptible isolates. The first ciprofloxacin-resistant S. Typhi infection in Taiwan is reported. The emergence and spread of antimicrobial-resistant S. Typhi infection as a result of international travel may become a threat to public health in Taiwan. Clinicians should be well alert when treating patients who may have acquired resistant infections associated with international travel among endemic regions.

Antimicrobial resistance and genotypes of staphylococci from bovine milk and the cowshed environment

Investigation of antimicrobial resistance and genetic relatedness of staphylococci from milk of cows with mastitis and cowshed environment was the aim of this study. Antimicrobial resistance against 14 antimicrobials were determined by using a disc diffusion method. Genetic similarity between the most frequently isolated species was analysed by PFGE (pulsed-field gel electrophoresis). Haemolytic activity, DNase, protease and esterase production was also investigated. Coagulase-negative Staphylococcus species were isolated from 30.8% of milk samples from cows with mastitis. The most frequently isolated species was Staphylococcus xylosus and yield of these organisms was significantly associated with milk of mastitis cows. S. epidermidis was a predominant penicillin-resistant species. High frequency of resistance to lincomycin was observed among isolates of S. sciuri (54.2%) and S. xylosus (25.9%) from cows with mastitis. PFGE (pulsed-field gel electrophoresis) analysis of 29 Staphylococcus aureus isolates showed the presence of 17 PFGE pulsotypes. Isolates of S. sciuri (n = 36) had unique PFGE patterns. Some S. xylosus isolates from milk and milker's hands had the same PFGE pulsotypes, and this observation could indicate that dairyman may be a potential source of the infection. The pulsotype of each of the remaining isolates of S. xylosus suggested that they might have come from common environmental sources; however, these isolates differed in antibiotic resistance pattern or virulence traits. Therefore, knowledge about antibiotic sensitivity pattern and virulence factors of a CNS isolate, besides its genotype, may be informative in tracking the source of the infection.

Molecular characterization of vancomycin-resistant Enterococcus spp. clinical isolates recovered from hospitalized patients among several medical institutions in China

The epidemiology and molecular characteristics of vancomycin-resistant enterococci (VRE) from China deserve further investigation. This study reports on the molecular characterization of 101 unique VRE (96 E. faecium and 5 E. faecalis strains) recovered from diverse samples of 12 hospitals in China. MIC results were obtained by reference broth microdilution methods, and vancomycin resistance and virulence genes were screened by polymerase chain reaction. All strains were subjected to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. E. faecalis exhibited vancomycin and teicoplanin MIC results at ≥256 μg/mL and harbored vanA, except for 1 vanB-carrying strain (MIC, 32 and 1 μg/mL, respectively). This strain had a unique PFGE pattern and was associated with ST410 (clonal complex [CC]4). E. faecium displayed vancomycin MIC values of ≥256 μg/mL with variable results for teicoplanin (1–256 μg/mL). One E. faecium had a teicoplanin MIC value of 1 μg/mL and carried a vanB, while the other 2 strains had teicoplanin MIC values of 4 and 8 μg/mL and harbored vanA. E. faecalis strains were susceptible to ampicillin, and all VRE displayed a susceptible phenotype to daptomycin, linezolid, and tigecycline. Four E. faecalis from a particular hospital were grouped within a single PFGE type and were associated with ST470 and ST471 (CC4), which are double- and triple-locus variants of ST410 and ST4, respectively. Overall, E. faecium displayed genetic variability, but clonal dissemination was noted within and among hospitals. All E. faecium belonged to STs associated with CC17, except for 1 strain (ST362; CC362). A total of 77.2% and 29.7% of all strains carried esp and hyl, respectively. In conclusion, these results show that vanA-carrying isolates predominated in strains from China, and E. faecium strains are usually associated with a common and human-adapted lineage (CC17). Unlike the majority of clinical E. faecalis (CC2 and CC9), strains included in this study showed ST profiles similar to ST4 (CC4), which has been associated with human infections in other Asia-Pacific countries.

Laboratory-Based Surveillance of Non-typhoidalSalmonellaInfections in Guangdong Province, China

Salmonella is one of the most common foodborne pathogens in humans. Laboratory-based surveillance for non-typhoidal Salmonella infection was conducted in Guangdong Province, China to improve understanding about the disease burden and detection of dispersed outbreaks. Salmonella isolated from patients with diarrhea were sent from 16 sentinel hospitals to local public health laboratories for confirmation, serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). PFGE patterns were analyzed to identify clusters representing potential outbreaks. Between September 2009 and October 2010, 352 (4%) Salmonella isolates were obtained from 9167 stool specimens. Salmonella enterica serotype Typhimurium (45%) and Salmonella enterica serotype Enteritidis (13%) were the most common serotypes, and multidrug resistance was high, especially in Salmonella Typhimurium isolates. PFGE patterns of obtained Salmonella isolates were found to be diverse, but a unique PFGE pattern comprising 53 Salmonella Typhimurium isolates were found to occur almost exclusively in infants. Epidemiologic studies are ongoing to determine whether a common exposure is the source of the Salmonella Typhimurium strain frequently isolated from infants.

Characterization of Salmonella Occurring at High Prevalence in a Population of the Land Iguana Conolophus subcristatus in Galápagos Islands, Ecuador

The aim of the study was to elucidate the association between the zoonotic pathogen Salmonella and a population of land iguana, Colonophus subcristatus, endemic to Galápagos Islands in Ecuador. We assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population. Additionally, we investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) on XbaI-digested DNA and determined the antimicrobial susceptibility to a panel of antimicrobials. The study was carried out by sampling cloacal swabs from animals (n = 63) in their natural environment on in the island of Santa Cruz. A high prevalence (62/63, 98.4%) was observed with heterogeneity of Salmonella subspecies and serovars, all known to be associated with reptiles and with reptile-associated salomonellosis in humans. Serotyping revealed 14 different serovars among four Salmonella enterica subspecies: S. enterica subsp. enterica (n = 48), S. enterica subsp. salamae (n = 2), S. enterica subsp. diarizonae (n = 1), and S. enterica subsp. houtenae (n = 7). Four serovars were predominant: S. Poona (n = 18), S. Pomona (n = 10), S. Abaetetuba (n = 8), and S.Newport (n = 5). The S. Poona isolates revealed nine unique XbaI PFGE patterns, with 15 isolates showing a similarity of 70%. Nine S. Pomona isolates had a similarity of 84%. One main cluster with seven (88%) indistinguishable isolates of S. Abaetetuba was observed. All the Salmonella isolates were pan-susceptible to antimicrobials representative of the most relevant therapeutic classes. The high prevalence and absence of clinical signs suggest a natural interaction of the different Salmonella serovars with the host species. The interaction may have been established before any possible exposure of the iguanas and the biocenosis to direct or indirect environmental factors influenced by the use of antimicrobials in agriculture, in human medicine or in veterinary medicine.

Outbreak of campylobacteriosis associated with consumption of raw peas.

Campylobacter jejuni is a leading cause of acute gastroenteritis worldwide, and most cases are identified as sporadic events rather than as parts of recognized outbreaks. We report findings from a substantial 2008 campylobacteriosis outbreak with general implications for fresh produce safety. We conducted a matched case-control study to determine the source of the outbreak and enhanced surveillance to identify additional cases. Clinical and environmental specimens were tested for Campylobacter, and isolates were subtyped by pulsed-field gel electrophoresis (PFGE). By routine surveillance, we identified 63 cases of laboratory-confirmed infection. Only raw peas, consumed by 30 (67%) of 45 case-patients and by 15 (17%) of 90 control participants, were associated with illness (adjusted odds ratio: 8.2; P<.001). An additional 69 patients (26 laboratory-confirmed) who reported eating raw peas within 10 days of illness onset were identified through enhanced surveillance. In all, 5 cases were hospitalized, and Guillain-Barré syndrome developed in 1 case; none died. The implicated pea farm was located near a Sandhill crane (Grus canadensis) stopover and breeding site. Of 36 environmental samples collected, 16 were positive for C. jejuni-14 crane-feces samples and 2 pea samples. We identified 25 unique combined SmaI-KpnI PFGE patterns among clinical isolates; 4 of these combined PFGE patterns identified in 15 of 55 human isolates were indistinguishable from PFGE patterns identified in environmental samples. This investigation established a rare laboratory-confirmed link between a campylobacterosis outbreak and an environmental source and identified wild birds as an underrecognized source of produce contamination.