Carriage and Fecal Counts of Cefotaxime M-Producing Escherichia coli in Pigs: a Longitudinal Study

Current knowledge on extended-spectrum beta-lactamases (ESBLs) in animals is based largely on cross-sectional studies and qualitative data. The aim of this longitudinal study was to elucidate carriage proportions and fecal counts of ESBL-producing Escherichia coli in pigs during the production cycle. At each of three ESBL-positive single-sited farrow-to-finisher pig farms (farms A, B, and C) included in the study, individual fecal samples were taken from 17 to 20 sows 1 week before farrowing and from 2 piglets of each sow''s litter four times from birth to slaughter (as piglets, weaners, and finishers). Cefotaxime (CTX)-resistant coliforms in feces were counted on MacConkey agar containing 2 μg/ml CTX and characterized for the presence of ESBL-encoding genes by PCR and sequencing. CTX-M-positive pigs were detected in all age groups at farms A (bla_CTX-M-9 group, compatible with bla_CTX-M-14/17) and B (bla_CTX-M-1 group, compatible with bla_CTX-M-1/61), whereas only three weaners were positive at farm C (bla_CTX-M-1 group, compatible with bla_CTX-M-1/61). A significant decrease in carriage was detected during the production cycle, with on average 50% carriage immediately after birth, 58% just before weaning, 29% during weaning, and 12% during finishing. The observed reduction in numbers of CTX-M-positive pigs was accompanied by a significant reduction in mean fecal counts of CTX-resistant coliforms from ∼10⁷ CFU/g in piglets to ∼10³ CFU/g in finishers (P < 0.001). These findings provide novel information about the epidemiology of ESBLs at the farm level and have important implications for assessments of risks of meat contamination during slaughter.     

Breaking membrane barriers to neutralize E. coli and K. pneumoniae virulence with PEGylated branched polyethylenimine

Bacterial infections caused by Gram-negative pathogens, such as those in the family Enterobacteriaceae, are among the most difficult to treat because effective therapeutic options are either very limited or non-existent. This raises serious concern regarding the emergence and spread of multi-drug resistant (MDR) pathogens in the community setting; and thus, creates the need for discovery efforts and/or early-stage development of novel therapies for infections. Our work is directed towards branched polyethylenimine (BPEI) modified with polyethylene glycol (PEG) as a strategy for targeting virulence from Gram-negative bacterial pathogens. Here, we neutralize lipopolysaccharide (LPS) as a barrier to the influx of antibiotics. Data demonstrate that the β-lactam antibiotic oxacillin, generally regarded as ineffective against Gram-negative bacteria, can be potentiated by 600 Da BPEI to kill some Escherichia coli and some Klebsiella pneumoniae. Modification of 600 Da BPEI with polyethylene glycol (PEG) could increase drug safety and improves potentiation activity. The ability to use the Gram-positive agent, oxacillin, against Gram-negative pathogens could expand the capability to deliver effective treatments that simplify, reduce, or eliminate some complicated treatment regimens.     

Transferable antibiotic resistance in E. coli and Klebsiella pneumoniae

Twenty-three of 43 E. coli and 25 of 39 Klebsiella isolates, resistant to two or more antibiotics, transferred one or more resistance genes to a recipient E. coli K₁₂ culture. Resistances transferred most frequently by both species were those to kanamycin and neomycin. E. coli cultures transferred resistance to tetracycline, chloramphenicol, ampicillin and carbenicillin, whereas Klebsiella isolates transferred resistance to the first two of these antibiotics. Extrapolation of these results to a larger series of isolations of E. coli and Klebsiella from hospital patients suggested that 21 and 18% respectively of cultures of these two organisms carried potentially transferable resistance.     

ESBL-Producing Enterobacteriaceae: Occurrence,Risk Factors for Fecal Carriage and Strain Traits in the Swiss Slaughter Cattle Population Younger than 2 Years Sampled at Abattoir Level

During the past decade extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae have become a matter of great concern in human and veterinary medicine. In this cross-sectional study fecal swabs of a geographically representative number of Swiss cattle at slaughterhouse level were sampled i) to determine the occurrence of ESBL producing Enterobacteriaceae in the Swiss slaughter cattle population younger than 2 years, and ii) to assess risk factors for shedding ESBL producing Enterobacteriaceae. In total, 48 (8.4%; 95% C.I. 6.3–11.1%) independent ESBL producing Enterobacteriaceae were detected among the 571 tested animals. Species identification revealed 46 E. coli strains, one Enterobacter cloacae and one Citrobacter youngae. In view of beta-lactam antibiotics, all 48 isolates were resistant to ampicillin, cephalothin and cefpodoxime. Forty-five (93.8%) isolates were resistant cefuroxime; one (2.1%) isolate to cefoxitin, 28 (58.3%) isolates to cefotaxime, 2 (4.2%) isolates to ceftazidime, and 2 (4.2%) isolates to cefepime. Risk factors for shedding ESBL producing Enterobacteriaceae were (i) age (OR 0.19 and 0.12 in age category 181 d to 1y and 1y to 2 y compared to ≤180 d), (ii) primary production type, meaning dairy compared to beef on farm of origin (OR 5.95), and (iii) more than 1 compared to less than 1 animal movement per d per 100 animals on farm of origin (OR 2.37).     

Immune Dysfunction in Children with CHARGE Syndrome: A Cross-Sectional Study

CHARGE syndrome is a variable, multiple congenital malformation syndrome. Patients with CHARGE syndrome have frequent infections that are presumed to be due to anatomical anomalies of the craniofacial region and upper airway, and cranial nerve problems resulting in swallowing difficulties and aspiration. The possible contribution of immunological abnormalities to these infections has not been systematically studied even though immune deficiencies have been described in patients with 22q11.2 deletion syndrome, a condition which shares remarkable clinical overlap with CHARGE syndrome. We assessed the frequency and nature of immune dysfunction in 24 children with genetically proven CHARGE syndrome. All patients, or their parents, completed a questionnaire on infectious history. Their immune system was extensively assessed through full blood counts, immunoglobulin levels, lymphocyte subpopulations, peripheral B- and T-cell differentiation, T-receptor excision circle (TREC) analysis, T-cell function, and vaccination responses. All CHARGE patients had a history of infections (often frequent), mainly otitis media and pneumonia, leading to frequent use of antibiotics and to hospital admissions. Decreased T-cell numbers were found in 12 (50%) patients, presumably caused by insufficient thymic output since TREC amounts were also diminished in CHARGE patients. Despite normal peripheral B-cell differentiation and immunoglobulin production in all patients, 83% of patients had insufficient antibody titers to one or more early childhood vaccinations. Based on our results, we recommend immunological evaluation of CHARGE patients with recurrent infections.     

recA mutants of E. coli K12: A personal turning point

A first year graduate student, Ann Dee Margulies, changed my research career in 1962 by challenging me to direct her in the isolation of recombination-deficient mutants of Escherichia coli K-12. She succeeded in isolating two mutants, which conjugated with donor strains and received the donor DNA, but could not recombine that DNA with their own chromosomes. Ann Dee showed that both mutants were much more sensitive to UV radiation than was the wild type. Furthermore, she showed that one of these mutants carried a single mutation affecting both recombination and resistance. This work, published in 1965, was the first demonstration of the recA gene of E. coli. Subsequent work led to the discovery of many more recombination genes, the phenomenon of post replication-recombination repair, the invention of the SOS hypothesis and the discovery of genes encoding proteins with similar primary structure and function in all major groups of organisms. This article honors the memory of Ann Dee.     

Lifestyle-Associated Risk Factors for Community-Acquired Methicillin-Resistant Staphylococcus aureus Carriage in the Netherlands: An Exploratory Hospital-Based Case-Control Study

Background

Community-acquired MRSA (CA-MRSA) is rapidly increasing. Currently, it is unknown which reservoirs are involved. An exploratory hospital-based case-control study was performed in sixteen Dutch hospitals to identify risk factors for CA-MRSA carriage in patients not belonging to established risk groups.

Methods

Cases were in- or outpatients from sixteen Dutch hospitals, colonised or infected with MRSA without healthcare- or livestock-associated risk factors for MRSA carriage. Control subjects were patients not carrying MRSA, and hospitalised on the same ward or visited the same outpatients'' clinic as the case. The presence of potential risk factors for CA-MRSA carriage was determined using a standardised questionnaire.

Results

Regular consumption of poultry (OR 2⋅40; 95% CI 1⋅08–5⋅33), cattle density per municipality (OR 1⋅30; 95% CI 1⋅00–1⋅70), and sharing of scuba diving equipment (OR 2⋅93 95% CI 1⋅19–7⋅21) were found to be independently associated with CA-MRSA carriage. CA-MRSA carriage was not related to being of foreign origin.

Conclusions

The observed association between the consumption of poultry and CA-MRSA carriage suggests that MRSA in the food chain may be a source for MRSA carriage in humans. Although sharing of scuba diving equipment was found to be associated with CA-MRSA carriage, the role played by skin abrasions in divers, the lack of decontamination of diving materials, or the favourable high salt content of sea water is currently unclear. The risk for MRSA MC398 carriage in areas with a high cattle density may be due to environmental contamination with MRSA MC398 or human-to-human transmission. Further studies are warranted to confirm our findings and to determine the absolute risks of MRSA acquisition associated with the factors identified.     

Completion of the IS map in E. coli: IS186 positions on the E. coli K12 chromosome

Summary Insertion sites of the transposable element IS186 were physically mapped in the genome of E. coli K12 strain BHB2600. This strain maintains four IS186 copies of which three, assigned to 0.3, 14.1 and 51.8 map min., share common map positions with the three IS186 copies in strains W3110 and HB101. The fourth, unique IS copy in BHB2600 maps at 49.3 min. The IS186 data complete the BHB2600 map for all chromosomal sites of known K12-associated IS types.     

大肠杆菌K5产肝素前体heparosan的研究进展

肝素是一种被广泛临床应用的抗凝血药物多糖。Heparosan是某些细菌荚膜中的GAG成分,其二糖骨架结构与脊椎动物中的肝素类似,可以作为肝素和硫酸乙酰肝素的生物合成前体。本文综述了肝素及肝素前体heparosan的功能与应用,heparosan在大肠杆菌K5中合成转运相关酶的研究,以及发酵法生产heparosan的研究进展,并对其应用前景进行了展望。     

Factors Associated to Prevalence and Incidence of Carbapenem-Resistant Enterobacteriaceae Fecal Carriage: A Cohort Study in a Mexican Tertiary Care Hospital

Background

Carbapenem-resistant Enterobacteriaceae (CRE) infections have emerged as a serious threat to health worldwide. They are associated with increased morbidity and mortality and are capable of silently colonizing the gastrointestinal tract. Because of this, there is great interest to characterize the epidemiology of CRE carriage and acquisition in healthcare facilities. The aim of this study was to determine the prevalence and factors associated with CRE fecal carriage (CRE-fc), and risk factors for incident cases.

Methods/Results

A cohort study was conducted at a tertiary care hospital from January 1^st to April 30^th, 2014 during a CRE outbreak. Weekly rectal swabs were performed in patients considered at risk until discharge. CRE-fc prevalence was 10.9% (CI 95% 7.7–14.7) among 330 patients. Treatment with carbapenems (OR 2.54, CI 95% 1.15–5.62); transfer from an institution (OR 2.16, CI 95% 1.02–4.59); multi-drug resistant infection within the previous six months (OR 2.81, CI 95% 1.47–5.36); intensive care unit admission (OR 0.42, CI 95% 0.20–0.88); hematologic malignancy (OR 4.02, CI 95% 1.88–8.06); invasive procedures (OR 2.18, CI 95% 1.10–4.32); and sharing a room with a known CRE carrier (OR 3.0, CI 95% 1.43–6.31) were independently associated factors for CRE-fc. Risk factors associated with CRE-fc incidence were determined for 87 patients initially negative and with subsequent screening; the incidence rate was 2.5 cases, per 1000 person-years (CI 95% 1.5–3.9). Independently associated risk factors were carbapenem treatment (HR 2.68, CI 95% 1.03–6.98), hematologic malignancy (HR 5.74, 95% CI 2.46–13.4) and a mean daily colonization pressure ≥10% (HR 5.03, IC 95% 1.77–14.28). OXA-48-like (OXA-232) and CTX-M-15 were the predominantly identified mechanisms of resistance.

Conclusions

We found an elevated incidence and prevalence of CRE-fc in our hospital. Hematologic patients need to be considered a population at risk, and antibiotic stewardship along with infection control programs need to be improved to avoid nosocomial spread.