Antimicrobial Resistance Screening Research Articles

Complex narratives of health, stigma and control: Antimicrobial resistance screening among non-hospitalized refugees

Antimicrobial resistance (AMR) is often presented as a major public health problem globally. Screening for AMR usually takes place in clinical settings. Recent developments in microbiology stimulated a series of studies focusing on AMR in communities, and particularly in travelers (any mobile individual), which was argued to be important for identifying potential public health risks. Against this background, microbiologists have become interested in non-hospitalized refugees as one of the traveler groups. However, this attention to refugees has provoked some professional debates on potential stigmatization of refugees as dangerous “others”. To contribute to these debates, and to explore the idea of AMR screening of non-hospitalized refugees from different perspectives, we conducted a qualitative study among four groups of stakeholders who were chosen because of their associations with potential microbiological screening: microbiologists, public health physicians, public health nurses, and refugees. The study took place in a Dutch city from June to August 2016 and had 17 participants: five microbiologists, two public health nurses, four public health physicians, and six refugees. While microbiologists and public health physicians demonstrated a de-contextualized biomedical narrative in arguing that AMR screening among non-hospitalized refugees could be important for scientific research as well as for AMR prevention in communities, public health nurses displayed a more contextualized narrative bringing the benefits for individuals at the center and indicating that screening exclusively among refugees may provoke fear and stigmatization. Refugees were rather positive about AMR screening but stressed that it should particularly contribute to their individual health. We conclude that to design AMR prevention strategies, it is important to consider the complex meanings of AMR screening, and to design these strategies as a process of co-production by diverse stakeholders, including the target populations.

Environmental emission of multiresistant Escherichia coli carrying the colistin resistance gene mcr-1 from German swine farms.

Pigs have been the focus of the worldwide spread of colistin resistance. However, there is little information on the transmission of mcr-1 -containing bacteria into the environment of pig farms. We therefore rescreened environmental Escherichia coli isolates from the surrounding farm areas of three previously mcr-1 -positive swine herds in Germany. Thirty-five mixed bacterial cultures obtained from boot swabs, flies, dog faeces and manure from three pig farms in Germany in 2011-12 were non-selectively recultivated and the presence of the mcr-1 gene was checked by real-time PCR. After separation, single E. coli colonies were subsequently isolated and the presence of mcr-1 was confirmed by PCR and sequencing. In addition, phenotypic antimicrobial resistance screening and WGS followed by phylogenetic analysis and resistance genotyping as well as plasmid typing were performed. Seven mcr-1 -positive E. coli strains originating from environmental boot swabs, dog faeces, stable flies and manure were found. The isolates belonged to five different STs (ST10, ST1011, ST1140, ST5281 and ST342) and harboured extensive additional resistance genes. Comparative plasmid analysis predominantly located mcr-1 on IncX4 plasmids, which are strongly related to a recently described plasmid of human clinical origin (pICBEC72Hmcr). WGS-based analysis of the environmental E. coli isolates of farm surroundings showed clear links to mcr-1 -harbouring E. coli recovered from pig production in Europe as well as from human clinical isolates worldwide, presenting another piece of the puzzle, which further complicates the rapidly evolving epidemiology of plasmid-mediated colistin-resistant E. coli strains.

Antimicrobial Resistance Trend of Bacteria from Clinical Isolates: An Eight-Year Retrospective Study at Dessie Regional Laboratory, Northeast Ethiopia

For decades, antimicrobials have proven useful for the treatment of bacterial infections. However, the immergence of antimicrobial resistance has become a major challenge to public health in many countries. The aim of this study was to investigate the antimicrobial susceptibility of bacterial isolates from clinical sources. A retrospective analysis of 1711 bacterial isolates was done at Dessie Regional Laboratory in the period 2003 - 2010. Antimicrobial susceptibility tests were done using disc diffusion technique as per the standard of Kirby-Bauer method. Escherichia coli with a figure 446 (26.1%), was the predominant isolate, followed by Staphylococcus aureus 429 (25.1%), Proteus spp. 303 (17.7%) and Pseudomonas spp. 290 (16.9%). These four species made up 85.8% of the organisms isolated from the clinical sources. The bacterial isolates showed high resistance rates to amoxicillin (85.4%) followed by tetracycline (84.1%) and erythromycin (73.5%). E. coli isolates showed resistance rates (>72 %) to amoxicillin, erythromycin and tetracycline. S. aureus isolates had resistance rates of 81.3% and 67.6% to amoxicillin and tetracycline, respectively. Proteus spp. showed resistance of >80% to amoxicillin, erythromycin and tetracycline. High resistance rates to erythromycin (91.6%) and amoxicillin (89.6%) were exhibited by Pseudomonas spp. A considerable degree of resistance rates to tetracycline (85.2%), chloramphenicol (72.8%) and cotrimoxazole (72.5%) were also observed. However, most bacterial isolates were susceptible to ciprofloxacin, norflaxocin and gentamicin with resistance rates ranging between 4 - 9.6%. All bacterial isolates showed high multiple antimicrobial resistances. Increased trend of resistance rates to all antimicrobials except nitofurantoin was demonstrated. Four of the most frequently isolated bacteria exhibited high rates of resistance to amoxicillin, chlorampheniciol, cotrimoxazole, erythromycin and tetracycline. Ciprofloxacin, gentamicin and nitrofurantoin remain antimicrobials of choice for empirical therapy of infections in the study area. Increased trend of antimicrobial resistance and high multiple antimicrobial resistance calls for periodic screening for antimicrobial resistance for empirical therapy. Key words: antimicrobial resistance, bacterial isolates, disc diffusion technique, retrospective analysis, northeast Ethiopia

Molecular characterization of extended-spectrum-β-lactamases producing Klebsiella pneumoniae and Escherichia coli from hospitalized patients in Oman

Extended-spectrum -lactamases (ESBLs) are plasmid encoded enzymes that confer resistance to -lactam antibiotics through the hydrolysis of the -lactam ring. ESBLs are distributed worldwide with an increasing incidence and prevalence in the Middle East due to the misuse of antibiotics and lack of coherent antimicrobial surveillance studies. The aim of study is to analyze molecularly the antimicrobial resistance mechanisms of 50 Escherichia coli and Klebsiella pneumoniae isolates from nosocomial infections in hospitalized patients in Oman. Screening for antimicrobial resistance (AR) and ESBL production was carried out with the disk diffusion and E-test methods following CLSI guidelines. ESBL producers were screened for blaCTX-M, blaSHV, and blaTEM resistance markers via PCR using gene-specific primers. All amplified PCR fragments will be sequenced to determine their allelic variants. In order to demonstrate the overall genotypic variation, Pulsed-Field Gel Electrophoresis (PFGE) analyses were done separately among all E. coli and K. pneumoniae isolates. According to the AR analysis, 82% (41/50) of isolates were determined to be ESBL producing bacteria. The percentages of isolates with genetic markers for blaCTX-M, blaSHV, and blaTEM were 73%, 24%, and 68%, respectively. Preliminary PFGE analyses demonstrated high level of variation among ESBL isolates compared to non-ESBL producers. Further surveillance studies are needed to describe better the AR situation in these hospitals in Oman. from 2009 American University in Cairo Research Conference Cairo, Egypt. 5 April 2009

Improved methods in the identification and screening for antimicrobial resistance: chromogenic screening for Staphylococcus aureus and methicillin resistance

New enzyme specific synthetic chromogenic substrates offer an advance in the laboratory screening and detection of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA), with increased efficiency, reduced labour costs and decreased turn around times, especially when incorporated into existing laboratory workflows, to support current methods of microbial identification and the detection of resistance.

Extended antimicrobial resistance screening of the dominant faecal Escherichia coli and of rare resistant clones

Fifty faecal samples from healthy adults were grown on MacConkey agar and three pink colonies were subcultured, identified to species level and their antimicrobial susceptibility determined. Forty-seven samples yielded 141 isolates of Escherichia coli that were susceptible to most antimicrobials. Resistance was noted for ampicillin (30.5%), chloramphenicol (12.1%), tetracycline (23.4%), trimethoprim (24.8%) and co-trimoxazole (22.7%). A direct faecal plating method was used for extended resistance screening with E. coli as the indicator organism. Zone breakpoints were determined using normalised resistance interpretation and gave similar susceptibility results. Eighty-eight isolates of E. coli from within the zones of inhibition revealed four times more antimicrobial resistance. Extended antimicrobial resistance screening both provides the susceptibility profile of the dominant E. coli isolate and detects greater resistance in rare isolates.

Development of a Microelectronic Chip Array for High-Throughput Genotyping of Helicobacter Species and Screening for Antimicrobial Resistance

A microelectronic array assay was developed to specifically genotype Helicobacter pylori versus Helicobacter heilmannii and to determine antimicrobial resistance. Helicobacter 16S rRNA and 23S rRNA genes were specifically generated with Helicobacter genus-specific primers, respectively. The single-nucleotide polymorphisms (SNPs) in 16S rRNA, 268T specific in the H. pylori sequence, and 263A specific in H. heilmannii were used as molecular markers for identification of H. pylori and H. heilmannii, respectively. A triple-base-pair resistant mutation, AGA965-967TTC in 16S rRNA, is known to be responsible for H. pylori tetracycline resistance and was detected to identify resistant strains. H. pylori macrolide resistance was determined by the identification of 3 defined mutations in the 23S rRNA gene using the same method. The assay could be directly used to detect H. pylori in feces. The assay performs multiple determinations, including identification of Helicobacter species and antibiotic resistances, on the same microelectronic platform and is highly amenable to the development of other DNA-based assays.

First Report of Salmonella Isolates with the DHA-1 AmpC β-Lactamase in the United Kingdom

Organisms expressing high levels of AmpC -lactamases are a major clinical concern, since they are resistant to all -lactams except for amdinocillin, cefepime, cefpirome, and carbapenems. Plasmid-borne AmpC -lactamases are increasingly reported amonggram-negativebacteriaworldwide.SomespeciesofEnterobacter, Citrobacter, Morganella, and Hafnia produce chromosomal -lactamases copiously. AmpC enzymes encoded by genes that have escaped from these chromosomal locations are now plasmid encoded in a range of pathogens, including Salmonella (11). More than 20 different plasmid-borne ampC genes have been identified (10). One of the encoded enzymes, DHA, was first described for Salmonella enterica serovar Enteritidis in Saudi Arabia in 1997 (3). A detailed study demonstrated that blaDHA-1 was located on an integron that originated from Morganella morganii (12). Plasmid-borne blaDHA genes have also been found in Klebsiella pneumoniae in France (2), Taiwan (13), and the United States (1, 7) and in Salmonella enterica serovar Montevideo in Korea (5). The first reports of AmpC enzymes from humans in the United Kingdom were of blaBIL-1 for Escherichia coli in 1992 (9) and blaCMY-3 for K. pneumoniae in 1995 (4); also, blaBIL-1 was reported for E. coli in 1997 (8). Recently, we have reported the isolation of a blaCMY-2-positive Salmonella enterica serovar Bredeney isolate from an avian source (6). Most plasmid-mediated ampC genes identified up to 1998 in the Mediterranean area belonged to the groups CMY-2 to CMY-4 and LAT-1 to LAT-4, but recently other types, such as FOX-3 and FOX-4, have been reported (11). Globally, the majority of AmpC-like enzymes reported to date for Salmonella have been CMY-2. During screening for antimicrobial resistance of 246,969 Salmonella isolates from humans in the United Kingdom between 1993 and 2003, we identified 104 isolates with resistance to ampicillin plus at least one of the following cephalosporins: cephalexin, cephradine, cefuroxime, ceftriaxone, and cefotaxime. This panel was subjected to further detailed phenotypic characterization, and 11 isolates presented a suggestive AmpC producer phenotype (AmpC enzymes, except ACC-1, confer resistance to cephamycins and to amoxicillin/clavulanate); these are currently being investigated. Two of these isolates, both of Salmonella enterica serotype Senftenberg, originating from patients hospitalized in London in 1996 (isolate A) and 1999 (isolate B), were positive for blaDHA in a multiplex AmpC-PCR (10). Subsequently, the blaDHA amplicon was sequenced, indicating 100% homology with blaDHA-1. The two isolates had different XbaI‐pulsed-field gel electrophesis and plasmid profiles. Isolates A and B carried plasmids of approximately 98 and 99 MDa, respectively. Transferability of cefoxitin resistance was assessed by conjugation. Isolate A transferred a 98-MDa plasmid (codifying cefoxitin resistance) to an E. coli recipient. Attempts to transfer the plasmid from isolate B by conjugation failed. However, it was successfully transferred to ElectroMAX DH10B E. coli cells (Invitrogen) by electroporation. This represents the first report of blaDHA-1 in the United Kingdom and for serotype Senftenberg worldwide. Laboratories should institute procedures for recognizing AmpC producers in cases where primary screening indicates resistance to expanded-spectrum cephalosporins. In addition, there should be routine surveillance to identify emerging genes which may present a threat to the treatment of invasive pathogens. This work was funded by the Department for Environment, Food and Rural Affairs, United Kingdom, project VM02136.

Rapid antimicrobial resistance screening method for Bacteroides intermedius

The purpose of the study was to validate a rapid resistance screening (RRS) method for antimicrobial susceptibility testing of a selected periodontopathic microorganism using the standard broth dilution method as a control. Twenty-five subgingival plaque samples from gingivitis or periodontitis sites were plated on Trypticase soy agar supplemented with 5% rabbit blood with antibiotic discs (RRS method) and without (control). The antibiotics tested were: Augmentin, clindamycin, erythromycin, metronidazole, penicillin G and tetracycline hydrochloride. Bacteroides intermedius isolated from both groups of plates were placed onto antibiotic supplemented Trypticase soy broth. The antibiotic susceptibilities of B. intermedius isolated from the plates with antibiotic discs and the standard broth method were compared. The results showed high sensitivity and predictability for the RRS method compared with the control. The percentage of agreement was: 100% for Augmentin 30 micrograms, clindamycin 2 micrograms and tetracycline 30 micrograms; 96% for erythromycin 15 micrograms, metronidazole 80 micrograms and penicillin 10 IU; 92% for penicillin 2 IU; 88% for erythromycin 2 micrograms and 84% for tetracycline 5 micrograms. The results of this study document the feasibility of the RRS method for testing antimicrobial resistance of whole samples if its efficacy can be demonstrated for other bacteria. This method may be a quick and useful test for the periodontal practitioner in determining the antibiotic susceptibility of periodontal plaque pathogens.