Susceptibilities of Campylobacter jejuni isolates from Germany to ciprofloxacin, moxifloxacin, erythromycin, clindamycin, and tetracycline

Structural basis of DNA recognition of the Campylobacter jejuni CosR regulator

Campylobacter jejuni is a foodborne pathogen commonly found in the intestinal tracts of animals. This pathogen is a leading cause of gastroenteritis in humans. Besides its highly infectious nature, C. jejuni is increasingly resistant to a number of clinically administrated antibiotics. As a consequence, the Centers for Disease Control and Prevention has designated antibiotic-resistant Campylobacter as a serious antibiotic resistance threat in the United States. The C. jejuni CosR regulator is essential to the viability of this bacterium and is responsible for regulating the expression of a number of oxidative stress defense enzymes. Importantly, it also modulates the expression of the CmeABC multidrug efflux system, the most predominant and clinically important system in C. jejuni that mediates resistance to multiple antimicrobials. Here, we report structures of apo-CosR and CosR bound with a 21 bp DNA sequence located at the cmeABC promotor region using both single-particle cryo-electron microscopy and X-ray crystallography. These structures allow us to propose a novel mechanism for CosR regulation that involves a long-distance conformational coupling and rearrangement of the secondary structural elements of the regulator to bind target DNA.

IMPORTANCE

Campylobacter jejuni has emerged as an antibiotic-resistant threat worldwide. CosR is an essential regulator for this bacterium and is important for Campylobacter adaptation to various stresses. Here, we describe the structural basis of CosR binding to target DNA as determined by cryo-electron microscopy and X-ray crystallography. Since CosR is a potential target for intervention, our studies may facilitate the development of novel therapeutics to combat C. jejuni infection.

Prevalence and antimicrobial susceptibility of Arcobacter species in human stool samples derived from out- and inpatients: the prospective German Arcobacter prevalence study Arcopath

Background

Arcobacter species, particularly A. butzleri, but also A. cryaerophilus constitute emerging pathogens causing gastroenteritis in humans. However, isolation of Arcobacter may often fail during routine diagnostic procedures due to the lack of standard protocols. Furthermore, defined breakpoints for the interpretation of antimicrobial susceptibilities of Arcobacter are missing. Hence, reliable epidemiological data of human Arcobacter infections are scarce and lacking for Germany. We therefore performed a 13-month prospective Arcobacter prevalence study in German patients.

Results

A total of 4636 human stool samples was included and Arcobacter spp. were identified from 0.85% of specimens in 3884 outpatients and from 0.40% of specimens in 752 hospitalized patients. Overall, A. butzleri was the most prevalent species (n = 24; 67%), followed by A. cryaerophilus (n = 10; 28%) and A. lanthieri (n = 2; 6%). Whereas A. butzleri, A. cryaerophilus and A. lanthieri were identified in outpatients, only A. butzleri could be isolated from samples of hospitalized patients. Antimicrobial susceptibility testing of Arcobacter isolates revealed high susceptibilities to ciprofloxacin, whereas bimodal distributions of MICs were observed for azithromycin and ampicillin.

Conclusions

In summary, Arcobacter including A. butzleri, A. cryaerophilus and A. lanthieri could be isolated in 0.85% of German outpatients and ciprofloxacin rather than other antibiotics might be appropriate for antibiotic treatment of infections. Further epidemiological studies are needed, however, to provide a sufficient risk assessment of Arcobacter infections in humans.

A Historical Review on Antibiotic Resistance of Foodborne Campylobacter

Campylobacter is one of the most commonly reported foodborne human bacterial gastrointestinal pathogens. Campylobacter is the etiological agent of campylobacteriosis, which is generally a self-limited illness and therefore does not require treatment. However, when patients are immunocompromised or have other co-morbidities, antimicrobial treatment may be necessary for clinical treatment of campylobacteriosis, macrolides and fluoroquinolones are the drugs of choices. However, the increase in antimicrobial resistance of Campylobacter to clinically important antibiotics may become insurmountable. Because of the transmission between poultry and humans, the poultry industry must now allocate resources to address the problem by reducing Campylobacter as well as antimicrobial use, which may reduce resistance. This review will focus on the incidence of antibiotic-resistant Campylobacter in poultry, the clinical consequences of this resistance, and the mechanisms of antibiotic resistance associated with Campylobacter.

Antibiotic susceptibility pattern and genotyping of campylobacter species isolated from children suffering from gastroenteritis

PURPOSE

To study the prevalence and the antimicrobial resistance of campylobacter species isolated from children suffering from gastroenteritis .

MATERIALS AND METHODS

A total of 125 stool samples were collected from children with gastroenteritis. The identification of isolates was performed with conventional methods as well as with molecular methods based on 16SrRNA species-specific gene amplification by PCR and product analysis. Resistance pattern of the isolated strains was determined using agar dilution method.

RESULTS

Conventional methods including sodium hippurate hydrolysis revealed that 12 (9.6%) samples were positive for Campylobacter species. Ten out of 12 Campylobacter spp. were identified as Campylobacter jejuni and 2 as Campylobacter coli but PCR assay revealed that five samples only were positive for Campylobacter and all were C. jejuni. Antimicrobial susceptibility to 10 antimicrobials was performed and all isolates (five isolates of C. jejuni) were susceptible to chloramphenicol, gentamicin and amikacin but all were resistant to ceftriaxone.

CONCLUSION

PCR assay method allows reliable detection of C. jejuni. C. jejuni was the most prevalent Campylobacter species. Gentamicin, amikacin and chloramphenicol were the most effective antibiotic.

Prevalence and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolated from cattle between 2002 and 2006 in France

Feces from 2,255 cattle (calves, young beef cattle, and culled cows) were collected at slaughter from nine departments across France. Campylobacter was recovered from 16.5% of the 2,255 samples (C. jejuni from 12.8% and C. coli from 3.7%), predominantly from calves. Antimicrobial resistance to six antibiotics of medical and/or veterinary interest was tested with the E-test. Resistance to tetracycline was found in most isolates (52.8% of C. jejuni isolates and 88.1% of C. coli isolates) in contrast to low but consistent resistance to ampicillin and erythromycin. Only two C. coli isolates were resistant to gentamicin. Multiple resistance was frequently detected in C. jejuni and C. coli isolates, and 0.8% (3 of 372) of the isolates were resistant to five of the six antimicrobials. An upward trend in the resistance to quinolones and fluoroquinolones in C. jejuni from calves was found; resistance to nalidixic acid reached 70.4% in 2006 and fluoroquinolone resistance increased from 29.7 to 70.4% during 2002 through 2006. All data were analyzed in parallel using clinical breakpoints or epidemiological cutoff values, and the results overlapped largely, except those for gentamicin. This 5-year survey (2002 through 2006) gives the first overview of the prevalence and antimicrobial resistance of C. jejuni and C. coli in cattle in France and documents to what extent cattle may contribute to the environmental reservoir of Campylobacter in France in the context of recurrent reports on links between human campylobacterioses and livestock. The results underline a notable increase in the resistance to fluoroquinolones in C. jejuni from cattle that may be of significant importance for public health.

Antimicrobial resistance of Campylobacter species isolated from edible bivalve molluscs purchased from Bangkok markets, Thailand

Campylobacter species have been recognized as the most commonly reported cause of bacterial gastroenteritis in humans. The increase of resistance rates to drugs of choice used for treatment in campylobacteriosis is becoming a public health concern. In parallel, the increased use of antimicrobials in aquaculture may lead to the emergence of resistant microorganisms and is likely to cause additional health risk to humans through food consumption. The study assesses the presence of antimicrobial resistance in Campylobacter species isolated from three groups of bivalve molluscs (bloody cockles, green mussels, and oysters) purchased from markets in Bangkok. Thirty samples were collected from each group. Susceptibility to three antimicrobials was determined using the Epsilometer test. Rates of erythromycin, nalidixic acid, and ciprofloxacin resistance in Campylobacter isolates were 72-84%, 28-40%, and 21-25%, respectively. There was no statistically significant difference in the prevalence of each antimicrobial resistance between the three groups. This study demonstrates a significant level of antimicrobial resistance in the Campylobacter spp. isolated from molluscs with a particular high rate of resistance to erythromycin. Consumption of raw molluscs contaminated with antimicrobial-resistant Campylobacter spp. may therefore result in resistant infections in humans.

Trends of norfloxacin and erythromycin resistance of Campylobacter jejuni/Campylobacter coli isolates recovered from international travelers, 1994 to 2006

BACKGROUND

Campylobacter sp. is a major cause of bacterial enterocolitis and travelers' diarrhea. Empiric treatment regimens include fluoroquinolones and macrolides.

METHODS

Over the period 1994 to 2006, 724 Campylobacter jejuni/Campylobacter coli isolates recovered from international travelers at the outpatient clinic of the Institute of Tropical Medicine, Antwerp, Belgium, were reviewed for their susceptibility to norfloxacin and erythromycin.

RESULTS

Norfloxacin resistance increased significantly over time in isolates from travelers returning from Asia, Africa, and Latin America. For the years 2001 to 2006, norfloxacin resistance rates were 67 (70.5%) of 95 for Asia, 20 (60.6%) of 33 for Latin America, and 36 (30.6%) of 114 for Africa. The sharpest increase was noted for India, with no resistance in 1994, but 41 (78.8%) of 52 resistant isolates found during 2001 to 2006. Erythromycin resistance was demonstrated in 20 (2.7%) isolates, with a mean annual resistance of 3.1% +/- 2.8%; resistance increased over time, with up to 3(7.5%) of 40 and 3 (8.6%) of 35 resistant isolates in 2004 and 2006, respectively (p < 0.05); there was no apparent geographic association. Combined resistance to norfloxacin and erythromycin was observed in five isolates.

CONCLUSIONS

The high resistance rates to fluoroquinolones warrant reconsideration of their use as drugs of choice in patients with severe gastroenteritis when Campylobacter is the presumed cause. Continued monitoring of the incidence and the spread of resistant Campylobacter isolates is warranted.

Role of the plasmid-encoded tet(O) gene in tetracycline-resistant clinical isolates of Campylobacter jejuni and Campylobacter coli

The prevalence of tetracycline resistance, tetracycline MICs and tet(O) gene localization were investigated in 83 Campylobacter isolates from patients suffering from acute gastroenteritis in Germany. Combined biochemical and molecular markers identified 74 isolates (89 %) as Campylobacter jejuni, including seven atypical isolates that failed to hydrolyse hippurate, and nine isolates (11 %) as Campylobacter coli. Tetracycline resistance was detected in six out of nine Campylobacter coli isolates (67 %) and 13 out of 74 C. jejuni isolates (18 %). Low-level tetracycline resistance was observed for C. coli (MIC 16 microg ml(-1) for all strains), whereas C. jejuni showed high-level resistance (MIC >256 microg ml(-1) for all strains). Both low- and high-level tetracycline resistance was associated with the presence of the tet(O) gene. In C. jejuni, tet(O) was plasmid-encoded in 54 % of tetracycline-resistant isolates, whereas in C. coli, tet(O) appeared to be located on the chromosome.

Trends in antimicrobial resistance in Campylobacter spp. causing traveler's diarrhea

The aim of this study was to analyze the evolution of the levels of resistance to nine antimicrobial agents in clinical isolates of Campylobacter spp. causing traveler's diarrhea during the period from 1993 to 2003. The antimicrobial resistance levels to ampicillin, amoxicillin plus clavulanic acid, chloramphenicol, tetracycline, erythromycin, gentamicin, clindamicin, nalidixic acid and ciprofloxacin were established by the method of Kirby-Bauer. Two subperiods (1993-1998 and 1999-2003) were chosen to compare the evolution of the levels of antimicrobial resistance. Mantel-Haenszel or Fisher's exact test was performed to determine statistical significance. High levels of resistance to four out of nine antimicrobial agents tested were detected: ampicillin (66.3%), nalidixic acid (52.2%), ciprofloxacin (46.7%), and tetracycline (42.4%). In addition, resistance levels of 20.6% to amoxicillin plus clavulanic acid were detected. An increase in the resistance levels between the two subperiods analyzed for those five antimicrobial agents was observed. This increase was statistically significant for ampicillin, nalidixic acid, and ciprofloxacin. Two cases of therapeutic failure during treatment with ciprofloxacin were detected. The level of resistance to the most commonly used antibacterial agents in the developing world is increasing in Campylobacter spp., the increase in the resistance to quinolones being of special concern.

Antibiotic resistance of Campylobacter jejuni and Campylobacter coli clinical isolates from Poland

We tested 102 Campylobacter jejuni and 6 Campylobacter coli clinical isolates from Poland. All were susceptible to erythromycin. Among the tested C. jejuni isolates 55.9% and 13.7% were resistant to ciprofloxacin and tetracycline, respectively. Replacement of Thr86 with Ile in GyrA and a plasmid-borne tet(O) gene were the main resistance mechanisms for fluoroquinolones and tetracycline, respectively.

Antimicrobial susceptibilities of Campylobacter jejuni isolates from hospitalized children in Athens, Greece, collected during 2004–2005

A total of 170 Campylobacter jejuni strains isolated from the stool of children with clinical gastroenteritis, aged from 3 months to 14 years, were collected during a two-year period (2004-2005). From the 170 strains 30% were resistant to ciprofloxacin (MIC > or = 4 microg/ml), 55% to tetracycline (MIC > 8 microg/ml), 13% to clindamycin (MIC > or = 8 microg/ml), 4% to ampicillin (MIC > 16 microg/ml), 6% to erythromycin (MIC > or = 8 microg/ml), 4% to coamoxiclav (MIC > or = 16/8 microg/ml) and 0% to gentamicin. Compared to previous reports from Greece, the antimicrobial resistance rates to erythromycin, ampicillin and coamoxiclav remain low, while they are still high for tetracycline and ciprofloxacin. Considering similar reports from many other countries and the high incidence of Campylobacter gastroenteritis worldwide, the value of ciprofloxacin as a first choice drug in the empiric treatment of the infection is questionable.

Evaluation of antimicrobial susceptibility patterns inCampylobacterspp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States

OBJECTIVE

To describe antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States.

DESIGN

Longitudinal study.

SAMPLE POPULATION

128 farms.

PROCEDURE

Samples and data were collected every 2 months from August 2000 to October 2001. Fecal samples were collected from calves and cows. Milk samples were obtained from the bulk tank and milk line filters. Environmental samples were obtained from a water source, feed bunks of lactating cows, and cattle housing areas. Campylobacter identification and antimicrobial susceptibility testing were performed at a central laboratory by use of microbroth dilution with 2 customized antimicrobial susceptibility panels.

RESULTS

460 and 1,570 Campylobacter isolates were obtained from organic and conventional dairy farms, respectively. Most isolates from both farm types were susceptible to most antimicrobial agents tested, and antimicrobial susceptibility of conventional dairy isolates was decreased, compared with organic dairy isolates. Low proportions of isolates resistant to ampicillin (< 10%) and moderate proportions resistant (30% to 60%) to kanamycin, sulfamethoxazole, and tetracycline were observed on both farm types. The proportion of isolates resistant to tetracycline was higher for conventional than organic farms.

CONCLUSIONS AND CLINICAL RELEVANCE

Campylobacter isolates from dairy cattle and farms managed organically and conventionally had similar patterns of antimicrobial resistance; the proportion of resistant isolates was higher for conventional than organic farms.

Resistance to three antimicrobial agents of Campylobacter isolated from organically- and intensively-reared chickens purchased from retail outlets

Resistance rates to three antimicrobials (ciprofloxacin, erythromycin and nalidixic acid) in Campylobacter isolated from organically- and intensively-reared chickens purchased from supermarkets and butcher's shops in London were determined. Significant differences in the minimum inhibitory concentrations (MICs) of nalidixic acid were found, with the highest values in unpackaged intensively-reared chickens and the lowest values in organically-reared chickens. Using pre-set breakpoints, all isolates from all groups of chickens were identified as resistant to erythromycin and nalidixic acid. All isolates from the organically-reared group were susceptible to ciprofloxacin. Of the supermarket intensively-reared chickens, 8.7% harboured resistant isolates, all on the external parts, indicating post-slaughtering contamination. The highest percentage (26.7%) was in chickens from butcher shops, mostly in the chicken cavities, suggesting a link to treatment on the farm.

A double mutation in the gyrA gene is necessary to produce high levels of resistance to moxifloxacin in Campylobacter spp. clinical isolates

The aim of this study was to compare different fluoroquinolones against Campylobacter spp., analysing the molecular mechanisms of resistance. Moxifloxacin exhibited the greatest activity of the quinolones tested, being active against isolates carrying a single mutation in the gyrA gene. High resistance levels to moxifloxacin were related to the presence of a double gyrA mutation.

Antimicrobial resistance among enteric pathogens

Diarrhea is a major cause of morbidity and mortality in infants and children worldwide. Use of antimicrobial therapy in children with bacterial diarrhea involves consideration of advantages and limitations of use of appropriate agents in the general population and in specific hosts. Antimicrobial agents for bacterial diarrhea should be prescribed with an appreciation of limitations including antimicrobial resistance. Studies from many countries have reported resistance to Campylobacter jejuni, Campylobacter coli, Shigella species, Salmonella species, and shiga toxin producing Escherichia coli. In many geographic areas of the world including the United States, resistance patterns have demonstrated a consistent increase over the course of time, with resistance occurring to several classes of antimicrobial agents. Resistance patterns are influenced by geographic location, year isolates were obtained, classes of antimicrobial agents, pressure exerted by antimicrobial use, and source of the isolate. Because antimicrobial resistance among enteric pathogens is a common finding, has increased over time, and varies by geographic location, constant monitoring of susceptibility patterns is necessary for selection of appropriate antimicrobial agents for therapy when indicated.

Pathogens resistant to antimicrobial agents: epidemiology, molecular mechanisms, and clinical management

Resistance to antimicrobial drugs is increasing at an alarming rate among both gram-positive and gram-negative bacteria. Traditionally, bacteria resistant to multiple antimicrobial agents have been restricted to the nosocomial environment. A disturbing trend has been the recent emergence and spread of resistant pathogens and resistance traits in nursing homes, the community, as well as in hospitals. This article reviews the epidemiology, molecular mechanisms of resistance, and treatment options for pathogens resistant to antimicrobial drugs.

A European survey of antimicrobial susceptibility among zoonotic and commensal bacteria isolated from food-producing animals

OBJECTIVE

To study antimicrobial resistance in zoonotic bacteria isolated from food animals in different countries using uniform methodology.

METHODS

Samples were taken at slaughter from chickens, pigs and cattle in four EU countries per host. Escherichia coli (indicator organism; n = 2118), Salmonella spp. (n = 271) and Campylobacter spp. (n = 1325) were isolated in national laboratories and MICs tested in a central laboratory against, where appropriate, ampicillin, cefepime, cefotaxime, ciprofloxacin, chloramphenicol, erythromycin, gentamicin, nalidixic acid, streptomycin, tetracycline and trimethoprim/sulfamethoxazole.

RESULTS

Isolation rates were high for E. coli, low for Salmonella and intermediate for Campylobacter. MIC results showed resistance prevalence varied among compounds, hosts and countries. For E. coli and Salmonella, resistance to newer compounds (cefepime, cefotaxime, ciprofloxacin) was absent or low, but to older compounds (except gentamicin), resistance was variable and higher. E. coli isolates from Sweden showed low resistance, whereas among isolates from Spain (pigs), resistance to ampicillin, chloramphenicol, streptomycin, tetracycline and trimethoprim/sulfamethoxazole was higher; the UK, France, the Netherlands, Germany, Italy and Denmark were intermediate. For Campylobacter spp. isolates from chickens, nalidixic acid and ciprofloxacin resistance was >30% in France and the Netherlands, >6% in the UK and zero in Sweden. Nalidixic acid resistance was high in cattle (20%-64%), whereas ciprofloxacin resistance was markedly lower in cattle, variable in pigs (3%-21%) and highest in Sweden. Generally, Campylobacter coli was more resistant than Campylobacter jejuni.

CONCLUSION

Antimicrobial resistance among enteric organisms in food animals varied among countries, particularly for older antimicrobials, but resistance to newer compounds used to treat disease in humans was generally low.

Genetic relatedness and quinolone resistance of Campylobacter jejuni strains isolated in 2002 in Hong Kong

Pulsed-field gel electrophoresis fingerprints of 98 Campylobacter jejuni isolates from patients (85) and chicken carcasses (13) in Hong Kong in 2002 demonstrated high genetic diversity. The prevalence of quinolone resistance among the isolates was 85.9%, and replacement of the threonine-86 residue in the gyrase subunit A was the major resistance mechanism.

Lincomycin, clindamycin and their applications

Lincomycin and clindamycin are lincosamide antibiotics used in clinical practice. Both antibiotics are bacteriostatic and inhibit protein synthesis in sensitive bacteria. They may even be bactericidal at the higher concentrations that can be reached in vivo. Clindamycin is usually more active than lincomycin in the treatment of bacterial infections, in particular those caused by anaerobic species; and it can also be used for the treatment of important protozoal diseases, e.g. malaria, most effectively in combination with primaquine. Resistance to lincomycin and clindamycin may be caused by methylation of 23S ribosomal RNA, modification of the antibiotics by specific enzymes or active efflux from the periplasmic space.

Inhibitory action of telithromycin against Shiga toxin and endotoxin

Shiga toxin (Stx)-producing Escherichia coli (STEC) is associated with hemolytic uremic syndrome (HUS). High inflammatory cytokine [interleukin (IL)-6 and IL-8] levels and low anti-inflammatory cytokine (IL-10) levels are indicators of a high risk for developing HUS in STEC-infected children. In this study, we investigated inhibitory action of telithromycin, a ketolide, against STEC and against Stx and lipopolysaccharide (LPS). Telithromycin inhibited in vitro STEC growth without inducing Stx phage, in marked contrast to norfloxacin. Stx markedly induced inflammatory (but not anti-inflammatory) cytokine production in human peripheral blood monocytes, while LPS induced both inflammatory and anti-inflammatory cytokine production. Telithromycin selectively inhibited the IL-6 and IL-8 production from Stx-stimulated (but not LPS-stimulated) monocytes. The drug did not significantly inhibit IL-10 production. Our data suggest that Stx plays a crucial role in the stimulation of inflammatory cytokines and such inflammatory response is inhibited by telithromycin, an anti-bacterial agent.