Åsa Melhus

Foreign Travel Is a Major Risk Factor for Colonization with Escherichia coli Producing CTX-M-Type Extended-Spectrum β-Lactamases: a Prospective Study with Swedish Volunteers

ABSTRACT Foreign travel has been suggested to be a risk factor for the acquisition of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. To our knowledge, this has not previously been demonstrated in a prospective study. Healthy volunteers traveling outside Northern Europe were enrolled. Rectal swabs and data on potential travel-associated risk factors were collected before and after traveling. A total of 105 volunteers were enrolled. Four of them did not complete the study, and one participant carried ESBL-producing Escherichia coli before travel. Twenty-four of 100 participants with negative pretravel samples were colonized with ESBL-producing Escherichia coli after the trip. All strains produced CTX-M enzymes, mostly CTX-M-15, and some coproduced TEM or SHV enzymes. Coresistance to several antibiotic subclasses was common. Travel to India was associated with the highest risk for the acquisition of ESBLs (88%; n = 7). Gastroenteritis during the trip was an additional risk factor (P = 0.003). Five of 21 volunteers who completed the follow-up after 6 months had persistent colonization with ESBLs. This is the first prospective study demonstrating that international travel is a major risk factor for colonization with ESBL-producing Enterobacteriaceae. Considering the high acquisition rate of 24%, it is obvious that global efforts are needed to meet the emergence and spread of CTX-M enzymes and other antimicrobial resistances.

Dissemination of Escherichia coli with CTX-M type ESBL between humans and yellow-legged gulls in the south of France

Extended Spectrum β-Lactamase (ESBL) producing Enterobacteriaceae started to appear in the 1980s, and have since emerged as some of the most significant hospital-acquired infections with Escherichia coli and Klebsiella being main players. More than 100 different ESBL types have been described, the most widespread being the CTX-M β-lactamase enzymes (bla CTX-M genes). This study focuses on the zoonotic dissemination of ESBL bacteria, mainly CTX-M type, in the southern coastal region of France. We found that the level of general antibiotic resistance in single randomly selected E. coli isolates from wild Yellow-legged Gulls in France was high. Nearly half the isolates (47,1%) carried resistance to one or more antibiotics (in a panel of six antibiotics), and resistance to tetracycline, ampicillin and streptomycin was most widespread. In an ESBL selective screen, 9,4% of the gulls carried ESBL producing bacteria and notably, 6% of the gulls carried bacteria harboring CTX-M-1 group of ESBL enzymes, a recently introduced and yet the most common clinical CTX-M group in France. Multi locus sequence type and phylogenetic group designations were established for the ESBL isolates, revealing that birds and humans share E. coli populations. Several ESBL producing E. coli isolated from birds were identical to or clustered with isolates with human origin. Hence, wild birds pick up E. coli of human origin, and with human resistance traits, and may accordingly also act as an environmental reservoir and melting pot of bacterial resistance with a potential to re-infect human populations.

The first major extended-spectrum β-lactamase outbreak in Scandinavia was caused by clonal spread of a multiresistant Klebsiella pneumoniae producing CTX-M-15†

Between May and December 2005, 64 multidrug‐resistant isolates of Klebsiella pneumoniae were detected from patients admitted to Uppsala University Hospital. This represented a dramatic increase in ESBL‐producing K. pneumoniae compared to previous years. To investigate the epidemiology and to characterize the resistance mechanisms of the isolates, a study was initiated. Antibiotic susceptibility was determined by means of the Etest and the disc diffusion method. Extended‐spectrum beta‐lactamase (ESBL) production was identified by clavulanic acid synergy test and confirmed with PCR amplification followed by DNA sequencing. DNA profiles of the isolates were examined with pulsed‐field gel electrophoresis (PFGE). All isolates were resistant or exhibited reduced susceptibility to cefadroxil, cefuroxime, cefotaxime, ceftazidime, aztreonam, piperacillin/tazobactam, ciprofloxacin, tobramycin, and trimethoprim‐sulfamethoxazole. They produced ESBL of the CTX‐M‐15 type, and the involvement of a single K. pneumoniae clone was shown. This is the first major clonal outbreak of multiresistant ESBL‐producing K. pneumoniae in Scandinavia. The outbreak demonstrates the epidemic potential of enterobacteria containing ESBLs of the CTX‐M type, even in a country with a relatively low selective pressure and a low prevalence of multiresistant bacteria.

Expression of cytokine genes during pneumococcal and nontypeable Haemophilus influenzae acute otitis media in the rat

ABSTRACT Acute otitis media (AOM) elicits potent inflammatory responses from the cells of the middle ear mucosa as well as from infiltrating leukocytes. To explore host responses during experimental AOM induced by Streptococcus pneumoniae type 3 and nontypeableHaemophilus influenzae (NTHi), otomicroscopy findings and expression of cytokine genes in the middle ear were monitored up to 1 month postinoculation. The mucosa and infiltrating cells responded rapidly to the bacterial challenge. Otomicroscopically, AOM appeared 1 day after NTHi inoculation and 3 days after pneumococcus inoculation. Pneumococcal AOM was more severe than NTHi otitis, but in general, lower transcript levels were detected in pneumococcus-infected than in NTHi-infected animals. Interleukin-6 (IL-6) mRNA levels peaked at 3 to 6 h for both pneumococcus-infected and NTHi-infected animals. IL-1α, tumor necrosis factor alpha, and IL-10 mRNA levels peaked at 6 h for NTHi otitis and 1 to 3 days for pneumococcal otitis. Comparing otomicroscopy with expression profiles, it would appear that the majority of cytokine mRNAs had passed their peak before the AOM diagnosis could be made clinically. Only transforming growth factor β mRNA followed a slower time course, peaking very late and continuing expression even after the AOM was otomicroscopically resolved. IL-2 and IL-4 mRNAs were not detected in any animal at any time. Most of the investigated cytokines are very early markers for AOM and may be involved in initiation of inflammation, but they would be poor targets for pharmacological manipulation since their levels decline before clinical signs appear.

A mouse model for acute otitis media

To induce acute otitis media in the mouse and to describe the clinical and bacteriological course of the infection, middle ears of BALB/c, Swiss‐Webster and C57BL/6 mice were inoculated with Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Systemic and local changes were monitored by clinical observations, otomicroscopy, and analysis of bacterial samples from blood and middle ears. Agglutination of mouse erythrocytes by M. catarrhalis was also tested. Depending on bacterial strain, bacterial dose, and mouse strain three responses were identified: acute otitis media, otitis media with serous effusion, or no reaction. BALB/c mice were the most susceptible animals. On day 3, 76% of the BALB/c mice had developed middle ear infection, 50% had a positive middle ear culture, 56% were bacteremic, and 10% had succumbed to a disseminated infection. The local infections lasted approximately a week. Animals which survived recovered without permanent deterioration or otomicroscopically discernible changes. In no case did M. catarrhalis induce a culture‐positive middle ear infection, possibly due to an inability to agglutinate the mouse erythrocytes. The mouse model can become a useful tool in studies of pneumococcal and H. influenzae‐induced otitis media, but the bacterial dose has to be carefully titrated and adjusted to the chosen mouse strain.

Revisiting the notion of type 1 diabetes being a T-cell-mediated autoimmune disease.

Purpose of review Type 1 diabetes (T1D) research is at present in a critical period of development and during the past few years several large phase III studies targeting T-cell autoimmunity in recent-onset patients with T1D failed to reach the primary endpoint. Recent findings Cause and pathogenesis of T1D remain largely unknown. In humans, insulitis is discrete, affects few islets and is present only in about one-third of patients with recent-onset T1D. The rapid increase in incidence of T1D argues against a decisive role for genetic factors and instead for the hypothesis that infectious agents, possibly entering the pancreas via the ductal compartment, are involved in disease pathogenesis. Repeated episodes of bacteria or virus-induced innate inflammations affecting only certain lobes of the pancreas fit well with the reported heterogeneity of the disease within the pancreas as well as with the slow progression over many years. Summary In humans there is limited support for T1D being primarily an autoimmune disease; instead available findings support the view that T1D can be regarded as an innate inflammatory disease affecting the entire pancreas, but with its main clinical manifestations emanating from the loss of the insulin-producing cells.

Globally disseminated human pathogenic Escherichia coli of O25b‐ST131 clone, harbouring blaCTX‐M‐15, found in Glaucous‐winged gull at remote Commander Islands, Russia

With focus on environmental dissemination of antibiotic resistance among clinically relevant bacteria, such as the rising ESBL type of resistance among Escherichia coli, we investigated antibiotic resistance levels in wild birds in the Commander Islands and Kamchatka, Russia. Despite overall low resistance levels in randomly selected E. coli (one from each sample), we found multi-resistant ESBL-producing E. coli harbouring blaCTX-M-14 and blaCTX-M-15 using selective screening. Among these multi-resistant ESBL-producing E. coli we found one blaCTX-M-15 harbouring strain belonging to the O25b-ST131 clone, recognized for its clonal disseminated worldwide as a human pathogen. The potential in acquiring resistant bacteria of human origin, especially highly pathogenic clones, as well as downstream consequences of that, should not be underestimated but further investigated.

On the etiology of type 1 diabetes : A new animal model signifying a decisive role for bacteria eliciting an adverse innate immunity response

The cause of type 1 diabetes (T1D) remains unknown; however, a decisive role for environmental factors is recognized. The increased incidence of T1D during the last decades, as well as regional differences, is paralleled by differences in the intestinal bacterial flora. A new animal model was established to test the hypothesis that bacteria entering the pancreatic ductal system could trigger β-cell destruction and to provide new insights to the immunopathology of the disease. Obtained findings were compared with those present in two patients dying at onset of T1D. Different bacterial species, present in the human duodenum, instilled into the ductal system of the pancreas in healthy rats rapidly induced cellular infiltration, consisting of mainly neutrophil polymorphonuclear cells and monocytes/macrophages, centered around the pancreatic ducts. Also, the islets of Langerhans attracted polymorphonuclear cells, possibly via release of IL-6, IL-8, and monocyte chemotactic protein 1. Small bleedings or large dilatations of the capillaries were frequently found within the islets, and several β-cells had severe hydropic degeneration (ie, swollen cytoplasm) but with preserved nuclei. A novel rat model for the initial events in T1D is presented, revealing marked similarities with the morphologic findings obtained in patients dying at onset of T1D and signifying a decisive role for bacteria in eliciting an adverse innate immunity response. The present findings support the hypothesis that T1D is an organ-specific inflammatory disease.

First documented case of bacteremia with vibrio vulnificus in Sweden

A few days after a mild trauma to a toe, a 90-year-old woman presented with fever, malaise and cellulitis. On suspicion of erysipelas the patient was initially treated with benzylpenicillin and cefuroxime. Her general condition improved rapidly, but there was local progression with numerous necrotic areas with surrounding bullae. Vibrio vulnificus was isolated from the blood. After susceptibility testing, the patient was finally treated with ciprofloxacin and pivampicillin, and recovered slowly. To our knowledge, this is the first reported case of bacteremia with V. vulnificus in Sweden.

Prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae in healthy Swedish preschool children.

The objective was to determine the prevalence of extended‐spectrum beta‐lactamase (ESBL)‐producing Enterobacteriaceae in faeces from healthy Swedish preschool children and to establish whether transmission took place between children in preschools.