Dominance of CTX-M-Type Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli Isolated from Patients with Community-Onset and Hospital-Onset Infection in China

Objective

To investigate CTX-M genotypes among extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) isolated from patients with community-onset and hospital-onset infections in China, their clonality and the distribution of CTX-M variants in different specimens of community-onset and hospital-onset infections.

Methods

ESBL-EC isolates were collected from general hospitals from 2011 to 2012 in China. Broth microdilution method antimicrobial susceptibility testing of 16 antibiotics was performed. Clinical data from community-onset and hospital-onset infections due to ESBL-EC were analyzed. ESBL-encoding genes were amplified by PCR and sequenced, and multilocus sequence typing (MLST) was performed for a random selection of predominant CTX-M type strains identified.

Results

A total of 1,168 ESBL-EC isolates were obtained from various clinical specimens, 41.7% of which were responsible for causing community-onset infections. The presence of urinary calculi was higher in community-onset infections, whereas malignancy, cardiovascular and cerebrovascular diseases, dementia, chronic renal disease, diabetes mellitus and surgical treatment were found to have higher proportions in hospital-onset infections. There was no significant difference in trauma between community-onset and hospital-onset infections. 96.2% of the isolates were detected to harbor bla _CTX-M genes. bla _CTX-M-1 group and bla _CTX-M-9 group were detected at 40.7% and 48.7% respectively, and both positive group accounted for 10.6%. bla _CTX-M-55 (24.8%) and bla _CTX-M-15 (18.2%) were the major genotypes in bla _CTX-M-1 group while bla _CTX-M-14 (46.8%) was predominant in bla _CTX-M-9 group. A comparison of bla _CTX-M distribution in different specimens between ESBL-EC causing community-onset and hospital-onset infection showed no significant difference. A total of 229 isolates were tested for MLST. ST131 (14%) was the predominant type. ST648, ST405 and ST1193 were also detected.

Conclusions

Community-onset ESBL-EC has emerged as a common pathogen in China. CTX-M-14 is the most commonly encountered, CTX-M-55 and CTX-M-15 have spread rapidly. ST131 is the predominant clonal group, and the great diversity of CTX-M-producing isolates of E. coli has emerged in China.     

Prevalence and Characteristics of Extended-Spectrum β-Lactamase and Plasmid-Mediated Fluoroquinolone Resistance Genes in Escherichia coli Isolated from Chickens in Anhui Province,China

The aim of this study was to characterize the prevalence of extended-spectrum β-lactamase (ESBL) genes and plasmid-mediated fluoroquinolone resistance (PMQR) determinants in 202 Escherichia coli isolates from chickens in Anhui Province, China, and to determine whether ESBL and PMQR genes co-localized in the isolates. Antimicrobial susceptibility for 12 antimicrobials was determined by broth microdilution. Polymerase chain reactions (PCRs), DNA sequencing, and pulsed field gel electrophoresis (PFGE) were employed to characterize the molecular basis for β-lactam and fluoroquinolone resistance. High rates of antimicrobial resistance were observed, 147 out of the 202 (72.8%) isolates were resistant to at least 6 antimicrobial agents and 28 (13.9%) of the isolates were resistant to at least 10 antimicrobials. The prevalence of bla _CTX-M, bla _TEM-1 and bla _TEM-206 genes was 19.8%, 24.3% and 11.9%, respectively. Seventy-five out of the 202 (37.1%) isolates possessed a plasmid-mediated quinolone resistance determinant in the form of qnrS (n = 21); this determinant occurred occasionally in combination with aac(6′)-1b-cr (n = 65). Coexistence of ESBL and/or PMQR genes was identified in 31 of the isolates. Two E. coli isolates carried bla _TEM-1, bla _CTX-M and qnrS, while two others carried bla _CTX-M, qnrS and aac(6′)-1b-cr. In addition, bla _TEM-1, qnrS and aac(6′)-1b-cr were co-located in two other E. coli isolates. PFGE analysis showed that these isolates were not clonally related and were genetically diverse. To the best of our knowledge, this study is the first to describe detection of TEM-206-producing E. coli in farmed chickens, and the presence of bla _TEM-206, qnrS and aac(6′)-1b-cr in one of the isolates.     

Characterization of Two New CTX-M-25-Group Extended-Spectrum β-Lactamase Variants Identified in Escherichia coli Isolates from Israel

Objectives

We characterized two new CTX-M-type extended-spectrum β-lactamase (ESBL) variants in Escherichia coli isolates from stool samples of two elderly patients admitted at the Tel Aviv Sourasky Medical Center, Israel. Both patients underwent treatment with cephalosporins prior to isolation of the E. coli strains.

Methods

ESBLs were detected by the double-disk synergy test and PCR-sequencing of β-lactamase genes. The bla _CTX-M genes were cloned into the pCR-BluntII-TOPO vector in E. coli TOP10. The role of amino-acid substitutions V77A and D240G was analyzed by site-directed mutagenesis of the bla _CTX-M-94 and bla _CTX-M-100 genes and comparative characterization of the resulting E. coli recombinants. MICs of β-lactams were determined by Etest. Plasmid profiling, mating experiments, replicon typing and sequencing of bla _CTX-M flanking regions were performed to identify the genetic background of the new CTX-M variants.

Results

The novel CTX-M β-lactamases, CTX-M-94 and -100, belonged to the CTX-M-25-group. Both variants differed from CTX-M-25 by the substitution V77A, and from CTX-M-39 by D240G. CTX-M-94 differed from all CTX-M-25-group enzymes by the substitution F119L. Glycine-240 was associated with reduced susceptibility to ceftazidime and leucine-119 with increased resistance to ceftriaxone. bla _CTX-M-94 and bla _CTX-M-100 were located within ISEcp1 transposition units inserted into ∼93 kb non-conjugative IncFI and ∼130 kb conjugative IncA/C plasmids, respectively. The plasmids carried also different class 1 integrons.

Conclusions

This is the first report on CTX-M-94 and -100 ESBLs, novel members of the CTX-M-25-group.     

Incidence of Extended-Spectrum β-Lactamases and Characterization of Integrons in Extended-Spectrum β-Lactamase-producing Klebsiella pneumoniae Isolated in Shantou, China

This study is concerned with the level of antibiotic resistance of extended-spectrum β-lactamase （ESBL）-producing Klebsiella pneumoniae, isolated in Shantou, China, and its mechanism. Seventy- four non-repetitive clinical isolates of K. pneumoniae producing ESBLs were isolated over a period of 2 years. Antibiotic susceptibility, carried out by Epsilometer test, showed that most of the isolates were multiresistant. Polymerase chain reaction showed that, among the several types of β-lactamases, SHV was the most prevalent, TEM was the second most prevalent, and CTX-M was the least prevalent. Sixty-nine isolates were positive for integrase gene IntI1, but no IntI2 or IntI3 genes were found. The variable region of class 1 integrons were amplified and further identified by sequencing. Thirteen different gene cassettes and 11 different cassette combinations were detected. Dfr and aadA cassettes were predominant and cassette combinations dfrA12, orfF and aadA2 were most frequently found. No gene cassettes encoding ESBLs were found. Integrons were prevalent and played an important role in multidrug resistance in ESBL-producing K. pneumoniae.     

Epidemiology of Extended-Spectrum β-Lactamase Producing Escherichia coli in the Stools of Returning Japanese Travelers,and the Risk Factors for Colonization

Objective

Travel overseas has recently been considered a risk factor for colonization with drug-resistant bacteria. The purpose of this study was to establish the epidemiology and risk factors associated with the acquisition of drug-resistant bacteria by Japanese travelers.

Methods

Between October 2011 and September 2012, we screened the stools of 68 Japanese returning travelers for extended-spectrum β-lactamase (ESBL) producing Escherichia coli. All specimens were sampled for clinical reasons. Based on the results, the participants were divided into an ESBL-producing E. coli positive group (18 cases; 26%) and an ESBL-producing E. coli negative group (50 cases; 74%), and a case-control study was performed. Microbiological analyses of ESBL-producing strains, including susceptibility tests, screening tests for metallo-β-lactamase, polymerase chain reaction amplification and sequencing of bla _CTX-M genes, multilocus sequence typing, and whole genome sequencing, were also conducted.

Results

In a univariate comparison, travel to India was a risk factor (Odds Ratio 13.6, 95% Confidence Interval 3.0–75.0, p<0.0001). There were no statistical differences in the characteristics of the travel, such as backpacking, purpose of travel, interval between travel return and sampling stool, and duration of travel. Although 10 of 13 analyzed strains (77%) produced CTX-M-15, no ST131 clone was detected.

Conclusion

We must be aware of the possibilities of acquiring ESBL-producing E. coli during travel in order to prevent the spread of these bacteria not only in Japan but globally.     

Prevalence of virulence and extended-spectrum β-lactamase (ESBL) genes harbouring Vibrio spp. isolated from cockles (Tegillarca granosa) marketed in Korea

This study aimed to examine incidence, virulence and antimicrobial properties in Aeromonas spp. isolated from cockles (Tegillarca granosa) in Korea. Firstly, genomic DNA was extracted from 32 Aeromonas spp. isolates, and PCR screening for virulence, antimicrobial resistance genes was carried out. The disk diffusion assay was used to examine antimicrobial susceptibility. Aeromonas spp. isolates comprised, A. hydrophila (n = 8), A. veronii (n = 15), A. media (n = 2), A. salmonicida (n = 2), A. allosaccharophila (n = 1), A. bestiarum (n = 1), A. culicicola (n = 1), A. enteropelogenes (n = 1) and A. rivipollensis (n = 1). High prevalence of virulence-related genes reported as; act (69%), alt (47%), ast (41%), aerA (56%), lip (50%), ahyB (47%), ser (28%), fla (66%), gcat (44%), ascV (50%) and hlyA (72%). All isolates were multidrug resistant, while highest resistance level observed for ampicillin (100%), followed by imipenem (81%), rifampicin (78%), cephalothin (72%), piperacillin (47%) and Colistin sulfate (31%). The presence of bla_SHV, bla_CTX, tetE, aac(6’)-Ib, strA-strB, qnrS, qnrB and IntI1 genes were reported in varying combinations. Nevertheless, bla_TEM, bla_IMP, tetA, tetB, qnrA, qnrB and aphAI-IAB genes and the class1 integron were not detected. The high occurrence of virulence and antimicrobial resistance genes in cockles reveals that it can be a potential health risk source for consumers.     

Products of acylase and β-Lactamase hydrolysis of some penicillins

The products of acylase of acylase and β-lactamase hydrolysis of 7 penicillins were determined by paper chromatography. The procedures used allowed us to detect also the product without antibiotic activity. When benzylpenicillin, phenoxymethylpenicillin, and ampicillin were hydrolyzed by cell suspension ofAlcaligenes faecalis of a high acylase activity, penicic acid and another unidentified metabolite, were found beside 6—APA. The hydrolysis of benzylpenicillin byEscherichia coli produced the same metabolites with prevailing benzylpenicilloic acid. The way of formation of penicic acid is discussed. Purified β-lactamase and cell suspension of the test or penicillin-resistent strain ofStaphylococcus aureus produced in all penicillins tested the same metabolite-corresponding penicilloic acid.     

Comparison of rhizobitoxine-induced inhibition of β-cystathionase from different bradyrhizobia and soybean genotypes

The enzyme -cystathionase catalyzes the conversion of cystathionine to homocysteine in both plants and bacteria. Preparations of this enzyme taken from both Salmonella and spinach (Spinacia oleracea L.) have been shown to be irreversibly inhibited by low concentrations of rhizobitoxine (RT), a chlorosis-inducing phytotoxin produced by some strains of soybean bradyrhizobia. The sensitivities of -cystathionase from bradyrhizobia and soybean are not well characterized. Therefore, we purified -cystathionase from selected bradyrhizobia and soybean genotypes that have been shown to exhibit differences in RT production and apparent RT sensitivities, respectively. Enzyme purified from E. coli strain DH52 was used for comparison. The enzymes differed in their physiological properties and RT sensitivities. Overall, the -cystathionase enzymes purified from bradyrhizobia were more sensitive to RT than were those from the soybean cultivars. Kinetic studies showed that the nature of the RT-induced inhibition also differed between the two sources. The enzymes from bradyrhizobia exhibited inhibition that was [RT]-dependent, whereas the enzymes from soybean showed a time-dependent inhibition. These contrasting characteristics may in part reflect differences in active site accessibility, amino acid components, and associated RT diffusion rates. However, in all cases the inhibition caused by RT showed a typical substrate-competitive inhibition pattern.Abbreviations RT rhizobitoxine - PLP pyridoxal phosphate - DTT dithioerythritol - PMSF phenylmethylsulfonyl fluoride - HTP hydroxyapatite Published as Paper No. 1571 in the Journal Series of the Delaware Agricultural Experiment Station.     

Molecular Characterization of CTX-M β-Lactamase and Associated Addiction Systems in Escherichia coli Circulating among Cattle,Farm Workers,and the Farm Environment

A total of 84 extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates from cattle, farm workers, and the farm environment isolated from February to September 2008 in the Republic of Korea were investigated. All 84 ESBL-producing isolates carried bla_CTX-M genes that belonged to the CTX-M-1 (n = 35) or CTX-M-9 (n = 49) family. The most predominant CTX-M type identified was CTX-M-14 (n = 49), followed by CTX-M-32 (n = 26). The bla_CTX-M genes were identified most commonly in E. coli isolates from feces (n = 29), teats (n = 25), and milk (n = 14). A bla_CTX-M-14 gene was also detected in an E. coli isolate from a farmer''s hand. Transfer of the bla_CTX-M gene from 60 bla_CTX-M-positive E. coli isolates to the recipient E. coli J53 strain by conjugation was demonstrated. Plasmid isolation from bla_CTX-M-positive transconjugants revealed a large (95- to 140-kb) conjugative plasmid. Almost all (82/84) bla_CTX-M genes possessed an insertion sequence, ISEcp1, upstream of the bla_CTX-M gene. Only in the case of the CTX-M-14 genes was IS903 downstream of the gene. The bla_CTX-M genes were associated with seven kinds of addiction systems. Among them, pndAC, hok-sok, and srnBC were the most frequently identified addiction systems in both wild strains and transconjugants. The spread of bla_CTX-M genes was attributed to both clonal expansion and horizontal dissemination. Our data suggest that a combination of multiple addiction systems in plasmids carrying bla_CTX-M genes could contribute to their maintenance in the host cells. To our knowledge, the bla_CTX-M-32 gene has not previously been reported in animal isolates from the Republic of Korea.     

PCR-Based Detection of Extended-Spectrum β-Lactamases (bla CTX-M-1 and bla TEM ) in Escherichia coli, Salmonella spp. and Klebsiella pneumoniae Isolated from Pigs in North Eastern India (Mizoram)

Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended-spectrum β-lactamases (ESBLs). A total of 138 enteric bacteria were isolated from 53 faecal samples of pigs collected from different districts of Mizoram, of which 102 (73.91 %) were Escherichia coli, 26 (18.84 %) were Salmonella spp. and 10 (7.25 %) were Klebsiella pneumoniae. Phenotypic confirmatory test (Double Discs Synergy Test) showed that 8 (5.80 %) E. coli isolates were ESBLs producer. PCR analysis confirmed that out of the eight isolate, 7 (5.07 %) harboured bla _CTX-M-1 gene and/or bla _TEM gene. Of the eight positive isolates, 7 (5.07 %) and 3 (2.17 %) were found to be positive for bla _CTX-M-1 gene and bla _TEM gene, respectively, of which 3 (2.17 %) isolates were positive for both the genes. Only 4 (2.90 %) E. coli isolates carried bla _CTX-M-1 gene alone. Agarose gel electrophoresis showed that all the isolates were carrying plasmids ranging between 0.9 and ~30 kb. Out of the seven isolates positive for bla _CTX-M-1 and/or bla _TEM , 2 (1.84 %) isolates were confirmed for bla _CTX-M-1 gene in their plasmid. Only one E. coli isolate was found to be positive for both the genes in its plasmid. The resistance plasmid could not be transferred to a recipient by in vitro horizontal gene transfer method.     

Genetic Detection of Extended-Spectrum β-Lactamase-Containing Escherichia coli Isolates from Birds of Prey from Serra da Estrela Natural Reserve in Portugal

Extended-spectrum β-lactamase-containing Escherichia coli isolates were detected in 32 of 119 fecal samples (26.9%) from birds of prey at Serra da Estrela, and these isolates contained the following β-lactamases: CTX-M-1 (n = 13), CTX-M-1 plus TEM-1 (n = 14), CTX-M-1 plus TEM-20 (n = 1), SHV-5 (n = 1), SHV-5 plus TEM-1 (n = 2), and TEM-20 (n = 1).The high and sometimes excessive use of antibiotics is directly related to the great spread and development of bacterial antibiotic resistance, a problem in public health nowadays. Thus, many studies have been done in order to understand the mechanisms of bacterial drug resistance, as many multidrug-resistant bacterial strains have been detected in domestic animals and humans (12). Recent studies from our research group have focused on wild animals, trying to understand how they acquire resistance to antibiotics without direct contact (11, 17, 20). One of the most clinically relevant antimicrobial resistance mechanisms is constituted by extended-spectrum β-lactamases (ESBLs) (3, 16) harbored by Enterobacteriaceae, such as Escherichia coli, commensals of the gastrointestinal tract of animals and humans, serving as a reservoir for resistances, namely, to β-lactam antibiotics (1, 15). Most ESBLs are derivatives of TEM or SHV enzymes, but a new family of plasmid-mediated ESBLs, CTX-M, has also been reported worldwide in E. coli and other Enterobacteriaceae. Different variants of the β-lactamase TEM, as in the case of TEM-1, are often reported in cases of plasmid-mediated β-lactamase resistance (2, 5, 8, 14, 21, 22). In this study, fecal samples from wild birds of prey at the Serra da Estrela Natural Reserve were analyzed in order to detect ESBL-containing E. coli isolates and characterize the type of ESBL-encoding genes and other associated resistance genes and the corresponding phylogenetic groups.One hundred nineteen fecal samples from birds of prey were recovered from April to July 2008 and studied for the presence of ESBL-containing E. coli strains (Table ​(Table1).1). All the fecal samples were collected individually from each animal and obtained in collaboration with CERVAS (Center of Ecology, Collecting, Welcome and Handling of Wild Animals). This Center receives injured animals found in its natural environments, is located at the Serra da Estrela Natural Reserve, and belongs to the Portuguese Institute of the Nature Management. None of the animals had been previously fed by humans or had received antibiotics. Each bird that arrives at CERVAS is placed in an individual cage to be treated and released back into the environment. Sampling was performed by recovering the fecal material in the cloaca by using a sterile swab. They were immediately transferred to peptone water and manipulated during the first 24 h of arrival to the laboratory. Samples were seeded in Levine agar supplemented with cefotaxime (2 mg/liter), and colonies with typical E. coli morphology were selected, identified by classical biochemical methods and by the API 20E system (bioMérieux, La Balme Les Grottes, France), and further studied. Susceptibility to 16 antibiotics (ampicillin, amoxicillin plus clavulanic acid [AMC], cefoxitin, cefotaxime [CTX], ceftazidime [CAZ], aztreonam [ATM], imipenem, gentamicin, amikacin, tobramycin, streptomycin, nalidixic acid, ciprofloxacin, sulfamethoxazole-trimethoprim, tetracycline, and chloramphenicol) was tested by the disc diffusion method (7) for all recovered E. coli isolates. E. coli ATCC 25922 was used as a quality control strain. The double-disc diffusion test (CTX, CAZ, and ATM in the presence or absence of AMC) was performed to detect ESBL production (7).

TABLE 1.

Animal species in which ESBL-positive E. coli isolates were recovered

Extended-Spectrum β-Lactamases and/or Carbapenemases-Producing Enterobacteriaceae Isolated from Retail Chicken Meat in Zagazig,Egypt

Objectives

The aim of the present study was to determine the prevalence and to characterize extended-spectrum β-lactamases- and/or carbapenemases-producing Enterobacteriaceae among Enterobacteriaceae isolated from retail chicken meat in Zagazig, Egypt.

Methods

One hundred and six Enterobacteriaceae isolates were collected from retail chicken meat samples purchased in Zagazig, Egypt in 2013. Species identification was done by MALDI-TOF MS. Screening for ESBL-E was performed by inoculation of isolates recovered from meat samples onto the EbSA (Cepheid Benelux, Apeldoorn, the Netherlands) selective screening agar. ESBL production was confirmed by combination disc diffusion test with clavulanic acid (Rosco, Taastrup, Denmark). Carbapenemases production was confirmed with double disk synergy tests. Resistance genes were characterized by PCR with specific primers for TEM, SHV, and CTX-M and carbapenemases (KPC, NDM, OXA-48, IMP and VIM). PCR products of CTX-M genes were purified and sequenced. Phylogenetic grouping of E. coli was performed by a PCR-based method.

Results

Of these 106 isolates 69 (65.09%) were ESBL producers. Twelve (11.32%) of these isolates were also phenotypically class B carbapenemases producer. TEM genes were detected in 61 (57.55%) isolates. 49 (46.23%) isolates harbored CTX-M genes, and 25 (23.58%) carried genes of the SHV family. All CPE belonged to the NDM group. The predominant CTX-M sequence type was CTX-M-15 (89.80%). The majority (80%) of the ESBL-EC belonged to low virulence phylogroups A and B1.

Conclusions

This is the first study from Egypt reporting high rates of ESBLs and carbapenemases (65.09% and 11.32%, respectively) in Enterobacteriaceae isolated from retail chicken meat. These results raise serious concerns about public health and food safety as retail meat could serve as a reservoir for these resistant bacteria which could be transferred to humans through the food chain.     

Comparison of the ability of β-glucosidases from almonds and Fusarium oxysporum to produce n-alkyl-β-glucosides in organic solvents

Summary The effect of water activity on the synthesis of n-alkyl-D-glucosides through condensation of glucose and n-alcohols has been studied using the commercially available almond -glucosidase and -glucosidase isolated from Fusarium oxysporum. The two enzymes exhibited a different water activity optimum. The specificity and alcohol reactivity of the two enzymes have also been investigated. Both enzymes prefer primary alcohols. -Glucosidase from F. oxysporum presents a higher affinity for primary alcohols with alkyl chain length of 4–6, whereas in the case of almond -glucosidase both initial velocity and yield decrease when the carbon chain length increases.     

Comparison of black–white disparities in preterm birth between Canada and the United States

Background:

A higher risk of preterm birth among black women than among white women is well established in the United States. We compared differences in preterm birth between non-Hispanic black and white women in Canada and the US, hypothesizing that disparities would be less extreme in Canada given the different historical experiences of black populations and Canada’s universal health care system.

Methods:

Using data on singleton live births in Canada and the US for 2004–2006, we estimated crude and adjusted risk ratios and risk differences in preterm birth (< 37 wk) and very preterm birth (< 32 wk) among non-Hispanic black versus non-Hispanic white women in each country. Adjusted models for the US were standardized to the covariate distribution of the Canadian cohort.

Results:

In Canada, 8.9% and 5.9% of infants born to black and white mothers, respectively, were preterm; the corresponding figures in the US were 12.7% and 8.0%. Crude risk ratios for preterm birth among black women relative to white women were 1.49 (95% confidence interval [CI] 1.32 to 1.66) in Canada and 1.57 (95% CI 1.56 to 1.58) in the US (p value for heterogeneity [p_H] = 0.3). The crude risk differences for preterm birth were 2.94 (95% CI 1.91 to 3.96) in Canada and 4.63 (95% CI 4.56 to 4.70) in the US (p_H = 0.003). Adjusted risk ratios for preterm birth (p_H = 0.1) were slightly higher in Canada than in the US, whereas adjusted risk differences were similar in both countries. Similar patterns were observed for racial disparities in very preterm birth.

Interpretation:

Relative disparities in preterm birth and very preterm birth between non-Hispanic black and white women were similar in magnitude in Canada and the US. Absolute disparities were smaller in Canada, which reflects a lower overall risk of preterm birth in Canada than in the US in both black and white populations.In the United States, a higher risk of preterm birth among black women than among white women is well established.^1–3 This racial disparity is of great concern because preterm birth is a leading cause of perinatal mortality and is predictive of developmental problems and adverse health outcomes later in life.⁴ The underlying causes of the racial disparity in preterm birth in the US are not well understood, although research has suggested contributing roles for a wide range of factors, including socioeconomic disadvantage,⁵ poor neighbourhood conditions (e.g., poverty, crime),^5,6 lack of access to health care,⁷ psychosocial stress,⁸ racial discrimination⁹ and adverse health behaviours.¹⁰Rates of preterm birth have consistently been lower in Canada than in the US.^11,12 However, in contrast to the US, little is known about differences in rates by race or ethnicity in Canada. There is evidence that African-born and Caribbean-born women in the provinces of Quebec and Ontario have higher rates of preterm birth than Canadian-born women.^13–15 Although the magnitude of these differences is smaller than the disparity in preterm births between black and white women in the US,¹⁶ foreign-born black women in the US have been found to be at lower risk of preterm birth than US-born black women.^17,18In both Canada and the US, socioeconomic conditions at both individual and neighbourhood levels are important predictors of preterm birth.^19–21 Although the income gap between black and white people is markedly smaller in Canada than in the US,²² black populations in both countries have lower education levels, higher unemployment rates and a greater likelihood of living in low-quality neighbourhoods compared with white populations.²³ Canada and the US share similar social and economic influences, yet the historical experiences of black populations and the social welfare systems (e.g., universal health care) are quite different in the 2 countries. Black people constitute about 13% of the total US population, but only about 3% of the Canadian population.^24,25 The overwhelming majority of Canada’s black population are immigrants who entered the country after 1960 and their descendants, whereas more than 85% of black Americans can trace their ancestry 3 or more generations in the US, with most being descendants of slaves.²²The objectives of our study are twofold. First, using data from a new cohort linking birth registrations with information from the 2006 Canadian long-form census, we present Canada-wide estimates of differences in preterm birth rates between black and white populations. Second, we use comparable methodology to compare racial differences in preterm birth rates between Canada and the US. Given different historical experiences of black populations in the 2 countries, as well as Canada’s commitment to universal health care and its general perception as a more egalitarian society than the US,²² we hypothesized that we would observe smaller racial disparities in the rates in Canada than in the US.     

Comparison of β-endorphin immunoreactivity in hypothalamic and brainstem nuclei of normotensive and age-matched hypertensive rat strains

The concentration of β-endorphin immunoreactivity was determined in 21 hypothalamic and brainstem nuclei of Sprague-Dawley (SD) and 6 and 14 week Wistar-Kyoto (WKY) and Spontaneously Hypertensive (SH) rats. The concentrations of β-endorphin immunoreactivity were greater in the hypothalamic nuclei than in the brainstem nuclei approximately by a factor of 5. A significant strain-age interaction was observed in the β-endorphin immunoreactivity levels in the anterior hypothalamic area, paragigantocellular reticular nucleus and locus coeruleus of age-matched SH and WKY rats in that immunoreactivity levels fell in the age period studied (6–14 weeks) in WKY rats and rose in SH rats. These biochemical differences are related in time to a growth period during which there are large increases in blood pressure in the SH rat and may thus have a pathogenetic significance.     

Phylogenetic Distribution and Prevalence of Genes Encoding Class I Integrons and CTX-M-15 Extended-Spectrum β-Lactamases in Escherichia coli Isolates from Healthy Humans in Chandigarh,India

Escherichia coli is generally considered as a commensal inhabitant of gastrointestinal tract of humans and animals. The aim of this study was to gain insight on the distribution of phylotypes and presence of genes encoding integrons, extended β-lactamases and resistance to other antimicrobials in the commensal E. coli isolates from healthy adults in Chandigarh, India. PCR and DNA sequencing were used for phylogenetic classification, detections of integrase genes, gene cassettes within the integron and extended β-lactamases. The genetic structure of E. coli revealed a non-uniform distribution of isolates among the seven phylogenetic groups with significant representation of group A. Integron-encoded integrases were detected in 25 isolates with class 1 integron-encoded intI1 integrase being in the majority (22 isolates). The gene cassettes identified were those for trimethoprim, streptomycin, spectinomycin and streptothricin. The dfrA12-orfF-aadA2 was the most commonly found gene cassette in intI1 positive isolates. Phenotypic assay for screening the potential ESBL producers suggested 16 isolates to be ESBL producers. PCR detection using gene-specific primers showed that 15 out of these 16 ESBL-producing E. coli harboured the bla _CTX-M-15 gene. Furthermore, molecular studies helped in characterizing the genes responsible for tetracycline, chloramphenicol and sulphonamides resistance. Collectively, our study outlines the intra-species phylogenetic structure and highlights the prevalence of class 1 integron and bla _CTX-M-15 in commensal E. coli isolates of healthy adults in Chandigarh, India. Our findings further reinforce the relevance of commensal E. coli strains on the growing burden of antimicrobial resistance.     

Evaluation of a double synergy differential test (DSDT) for differential detection of ESBL and AmpC-type β-lactamases in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis

This work describes a simple and practical double synergy differential test (DSDT) that couples the detection of ESBLs and AmpC-type enzymes by means of a combo-disk approach using cefotaxime and ceftazidime as indicator substrates, and clavulanate and boronic acid as enzyme inhibitors. The DSDT was tested with a collection of 118 Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis strains with different beta-lactamase profiles, and proved to be highly sensitive and specific for the detection of ESBL and AmpC-producing isolates.     

Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Enterobacteriaceae Isolated from Egyptian Patients with Suspected Blood Stream Infection

ObjectivesThe aim of the study was to investigate the prevalence of extended-spectrum β-lactamase and carbapenemase production among Enterobacteriaceae isolated from Egyptian patients with suspected blood stream infection.MethodsNinety-four Enterobacteriaceae blood culture isolates from Egyptian patients with suspected blood stream infection were collected, one isolate per patient. Identification of bacterial isolates was performed with MALDI-TOF (MS-based Vitek MS system, bioMerieux). Screening for ESBLs and carbapenemases production was done with the Vitek 2 system (bioMérieux). ESBL production was confirmed using the combined disk diffusion method for cefotaxime, ceftazidime, and cefepime, all with and without clavulanic acid (Rosco). Real-time PCR and sequencing were used to characterize the resistance genes. The phylogenetic groups of E. coli were identified by a PCR-based method.ResultsOf the 94 Enterobacteriaceae isolates 46 (48.93%) showed an ESBL phenotype. One Enterobacter spp isolate was ESBL-producer and meropenem-resistant. The genetic analysis showed that CTX-M was present in 89.13% (41/46) of the ESBL-producing Enterobacteriaceae, whereas TEM and SHV were detected in 56.52% (26/46) and 21.74% (10/46) respectively (47.83%) of the ESBL-producing isolates were multidrug resistant (MDR). Eleven out of 30 ESBL-producing E-coli isolates were assigned to phylogroup B2, followed by groups B1 (8 isolates), A (6 isolates) and D (5 isolates).ConclusionsThe high ESBL-E rates (48.93%) found in this study together with the identification of one carbapenem-resistant Enterobacter spp isolate is worrisome. Our results indicate that systems for monitoring and detection of ESBL-producing bacteria in Egyptian hospitals have to be established. Also strict hospital infection control policies with the restriction of the consumption of extended-spectrum cephalosporins are necessary.     

Purification and Characterization of β-d-Galactosidase and α-d-Mannosidase from Papaya (Carica papaya) Seeds

β-D-Galactosidase was purified 115-fold from a saline extract of papaya seeds by fractionation with ammonium sulfate, DEAE-Sephadex chromatography and gel-filtration on Sephadex G-75, G-150, and G-100. The purified β-D-galactosidase (MW, 56,000 daltons) had an isoelectric point (pI) at pH 8.4 and the optimal pH for its activity was 3.5 to 4.5. The enzyme activity was inhibited by Cu²⁺,Ag⁺,Hg²⁺,Pb²⁺,NaAsO₂ and р-chloromercuribenzoate at concentrations of 1x10^-3 M. Among the various mono- and oligosaccharides tested, D-galactose, D-galacturonic acid, D-galactono-γ-lactone and melibiose significantly inhibited the enzyme activities at concentrations of 2xl0^-3 to 1X10^-2M. The purified enzyme hydrolyzed β-nitrophenyl β-D-galactoside (Km = 1.0X10^-3M), methyl β-D-galactoside (Km=1.6x10^-2M), aminoethyl β-D-galactoside (Km =3.3X10^-2M) and lactose (Km = 9.1X10^-2M). β-(l→3)-Linked galactotetraosyl-eryth itol and asialo-glycopeptide isolated from fetuin were also hydrolyzed to the extent of 78 and 75%, 4respectively, on the basis of their galactose contents.

∝-D-Mannosidase from papaya seeds was also purified 130-fold by ammonium sulfate fractionation, DEAE-Sephadex chromatography, gel-filtration on Sephadex G-150 and hydroxylapatite chromatography. The purified enzyme (MW, 156,000 daltons), consisting of two subunits (78,000x2), was inhibited by Hg²⁺,Ag⁺,Cu²⁺, р-chloromercuribenzoate, D-glucose, D-glucosamine and D-mannose at concentrations of lx10^-3 to 1x10^-2M. The ∝-D-mannosidase hydrolyzed р-nitrophenyl ∝-D-mannoside (Km=5.6x10^-3M), methyl ∝-D-mannoside (Km=2.8X10^-2M), ∝-D-mannosyl-D-mannitol (Km=2.2X10^-2M), ∝-(l→2)linked D-mannobiosyl-D-mannitol (Km=6.3x10^-3M) and D-mannotriosyl-D-mannitol (Km=5.3x10^-3 M).