Resistance Rates For Tetracycline Research Articles

Antimicrobial Resistance Patterns of Outpatient Staphylococcus aureus Isolates

Oral non-β-lactam antibiotics are commonly used for empirical therapy of Staphylococcus aureus infections, especially in outpatient settings. However, little is known about potential geographic heterogeneity and temporal trends in the prevalence of S aureus resistance to non-β-lactams in the US. To characterize the spatiotemporal trends of resistance to non-β-lactam antibiotics among community-onset S aureus infections, including regional variation in resistance rates and geographical heterogeneity in multidrug resistance. This cross-sectional study used data from Veterans Health Administration clinics collected from adult outpatients with S aureus infection in the conterminous 48 states and Washington, DC, from January 1, 2010, to December 31, 2019. Data were analyzed from January to November 2023. Resistance to lincosamides (clindamycin), tetracyclines, sulfonamides (trimethoprim-sulfamethoxazole [TMP-SMX]), and macrolides. Spatiotemporal variation of S aureus resistance to these 4 classes of non-β-lactam antibiotics, stratified by methicillin-resistant S aureus (MRSA) and methicillin-sensitive S aureus (MSSA), and subdivided by regions of the US (Northeast, Midwest, South, and West). Trend tests and bivariate mapping were used to determine significant changes in resistant proportions over time and identify counties where rates of resistance to multiple non-β-lactams were high. A total of 382 149 S aureus isolates from 268 214 unique outpatients (mean [SD] age, 63.4 [14.8] years; 252 910 males [94.29%]) were analyzed. There was a decrease in the proportion of MRSA nationwide, from 53.6% in 2010 to 38.8% in 2019. Among MRSA isolates, we observed a significant increase in tetracycline resistance (from 3.6% in 2010 to 12.8% in 2019; P for trend < .001) and TMP-SMX resistance (from 2.6% in 2010 to 9.2% in 2019; P for trend < .001), modest and not significant increases in clindamycin resistance (from 24.2% in 2010 to 30.6% in 2019; P for trend = .34), and a significant decrease in macrolide resistance (from 73.5% in 2010 to 60.2% in 2019; P for trend < .001). Among MSSA isolates, significant upward trends in clindamycin, tetracyclines, and TMP-SMX resistance were observed. For example, tetracycline resistance increased from 3.7% in 2010 to 9.1% in 2019 (P for trend < .001). Regional stratification over time showed that the Northeast had slightly higher rates of clindamycin resistance but lower rates of tetracycline resistance, while the South had notably higher rates of resistance to tetracyclines and TMP-SMX, particularly among MRSA isolates. Bivariate mapping at the county scale did not indicate clear regional patterns of shared high levels of resistance to the 4 classes of antimicrobials studied. In this study of outpatient S aureus isolates, MRSA became less common over the 10-year period, and MRSA isolates were increasingly resistant to tetracyclines and TMP-SMX. Geographic analysis indicated no spatial overlap in counties with high rates of resistance to both tetracyclines and TMP-SMX. Examining the regional spatial variation of antibiotic resistance can inform empirical therapy recommendations and help to understand the evolution of S aureus antibiotic resistance mechanisms.

Meta-Analysis on the Global Prevalence of Tetracycline Resistance in Escherichia coli Isolated from Beef Cattle.

Antimicrobial resistance (AMR) is an emerging global concern, with the widespread use of antimicrobials in One Health contributing significantly to this phenomenon. Among various antimicrobials, tetracyclines are extensively used in the beef cattle industry, potentially contributing to the development of resistance in bacterial populations. This meta-analysis aimed to examine the association between tetracycline use in beef cattle and the development of tetracycline resistance in Escherichia coli isolates. A comprehensive search was conducted using multiple databases to gather relevant observational studies evaluating tetracycline use and tetracycline resistance in Escherichia coli isolates from beef cattle. The rate of tetracycline resistance from each study served as the effect measure and was pooled using a random-effects model, considering possible disparities among studies. The meta-analysis of 14 prospective longitudinal studies resulted in a 0.31 prevalence of tetracycline resistance in Escherichia coli in non-intervention (no exposure), contrasting numerically elevated resistance rates in the intervention (exposed) groups of 0.53 and 0.39 in those receiving tetracyclines via feed or systemically, respectively. Despite the observed numerical differences, no statistically significant differences existed between intervention and non-intervention groups, challenging the conventional belief that antimicrobial use in livestock inherently leads to increased AMR. The findings of this study underscore the need for additional research to fully understand the complex relationship between antimicrobial use and AMR development. A considerable degree of heterogeneity across studies, potentially driven by variations in study design and diverse presentation of results, indicates the intricate and complex nature of AMR development. Further research with standardized methodologies might help elucidate the relationship between tetracycline use and resistance in Escherichia coli isolated from beef cattle.

The Helicobacter pylori single nucleotide polymorphisms SNPs associated with multiple therapy resistance in Colombia.

The eradication of Helicobacter pylori (H. pylori) using multiple therapies is used as a prevention strategy. However, its efficacy has been compromised by the emergence of single nucleotide polymorphisms in genes associated with H. pylori's resistance to multiple antibiotics. To estimate antibiotic resistance rates associated with mutations in H. pylori genes in the high-cancer-risk population in Colombia, we included 166 H. pylori whole genome sequences from a cohort of individuals with a high risk of gastric cancer. By using the reference strain ATCC 26695, we identified mutations in specific genes to evaluate resistance rates for different antibiotics: 23S rRNA for clarithromycin, 16S rRNA for tetracycline, pbp1A for amoxicillin, gyrA for levofloxacin, and rdxA for metronidazole. The phylogenomic analysis was conducted using the core genome consisting of 1,594 genes of H. pylori-ATCC 26695. Our findings revealed that the resistance rate of H. pylori to clarithromycin was 3.62%, primarily associated with mutations A2143G and A2142G in the 23S rRNA gene. For tetracycline, the resistance rate was 7.23%, with mutations A926G, A926T, and A928C observed in the 16S rRNA gene. Amoxicillin resistance was found in 25.9% of cases, with observed mutations in the pbp1A gene, including T556S, T593, R649K, R656P, and R656H. In the gyrA gene, mutations N87K, N87I, D91G, D91N, and D91Y were identified, resulting in a resistance rate of 12.04% to levofloxacin. The most common mutations in the rdxA gene associated with metronidazole resistance were a stop codon, and mutations at D59N and D59S, resulting in a resistance rate of 99.3%. The high resistance rate of H. pylori to metronidazole indicated that this drug should be excluded from the eradication therapy. However, the resistance rates for tetracycline and clarithromycin did not exceed the established resistance threshold in Colombia. The increased resistance rate of H. pylori to levofloxacin and amoxicillin may partially explain the observed therapeutic failures in Colombia. The phylogenomic tree showed that the H. pylori isolate belongs to its own lineage (hspColombia). These findings offer valuable insights to enhance the characterization of treatment protocols for the specific H. pylori lineage (hspColombia) at the local level.

Identification of Emerging Multidrug-Resistant Neisseria gonorrhoeae Isolates against Five Major Antimicrobial Agent Options

Antimicrobial drug resistance in Neisseria gonorrhoeae has been documented all over the world. However, the situation in Sub-Saharan Africa has received little attention. It is critical to establish diagnostics and extend surveillance in order to prevent the emergence of illnesses that are resistant to several treatments. Monitoring antimicrobial susceptibility is critically required in order to gather data that may be utilised to produce treatment recommendations that will result in effective therapy, a decrease in gonorrhoeae-related difficulties and transmission, and effective therapy. Government authorities may set research and preventive objectives, as well as treatment recommendations, using data from the Gonococcal Antimicrobial Surveillance Program (GISP). Local and state health authorities may use GISP data to make choices about the allocation of STI prevention services and resources, to guide preventative planning, and to disseminate information about the most successful treatment practices. Using molecular and culture approaches, we investigated the occurrence of antibiotic resistance in isolates from KwaZulu Natal, South Africa. The great majority of gonococcal isolates (48% showed absolute resistance to ciprofloxacin), with penicillin and tetracycline resistance rates of 14% each. Only one of the gonococcal isolates tested positive for azithromycin resistance, with a minimum inhibitory concentration (MIC) of 1.5 µg/mL. Ceftriaxone was effective against all gonococcal isolates tested.

Bacterial Etiologies of Ear Infection and Their Antimicrobial Susceptibility Pattern at the University of Gondar Comprehensive Specialized Hospital, Gondar, Northwest Ethiopia: A Six-Year Retrospective Study.

BackgroundAn ear infection is responsible for up to 40% of preventable hearing impairment; one of the reasons for frequent and unwise antibiotic usage, especially in the developing world. Since the incidence of antibiotic resistance is increasing, especially in resource-limited countries, up-to-date knowledge on the susceptibility of ear-discharge isolates to antibiotic is important for better patient treatment. Therefore, this study aimed at determining the bacterial etiologies and their antibiotic susceptibility profiles among patients suspected with ear infections.MethodsWe collected retrospective data from bacteriological results of ear discharge samples from 2013 to 2018. Sample collection, culture preparation, and bacterial identification were performed using standard microbiological techniques. Antimicrobial susceptibility testing was performed following Clinical and Laboratory Standard Institute (CLSI) guidelines. We extracted and inputted the data using Epi-info version 7 and exported it to SPSS version 20 for analysis.ResultsThe overall ear-discharge culture positivity rate was 283/369 (76.7%) (95% CI = 72.4–81.3), with 14/283 (4.95%) mixed infections. Staphylococcus aureus (27.9%), Proteus spps (20.8%), Streptococcus spps (10%), and Pseudomonas spps (8.92%) were the main isolates. High-level resistance rates for tetracycline (77.6%), penicillins (67.2%), erythromycin (52.6%), and co-trimoxazole (52%), and low-level resistance rates for fluoroquinolones (23.3%), aminoglycosides (23.7%), and cephalosporins (29.8%) were observed. More than 45% of isolates, with 50.9% of Gram-negative and 37.3% of Gram-positive, were multidrug-resistant.ConclusionStaphylococcus aureus, Proteus mirabilis, Proteus vulgaris, Escherichia coli, and Pseudomonas aeruginosa were the leading cause of ear infections. The presence of high number of multidrug-resistant strains calls for the need for periodic and continuous follow-up of antibiotic usage in the study area. Further studies are recommended to explore the types of ear infections, with their etiologic agents and possible risk factors.

MYCO WELL D-ONE detection of Ureaplasma spp. and Mycoplasma hominis in sexual health patients in Wales

The genital mycoplasmas are a unique group of inherently antibiotic-resistant sexually transmitted bacteria, often associated with non-gonococcal urethritis and bacterial vaginosis. The MYCO WELL D-ONE is a culture-based assay that aims to detect these organisms whilst concurrently screening them for antibiotic resistance. Urine and/or swabs from 856 informed and consented participants attending Welsh sexual health clinics were subjected to MYCO WELL D-ONE analysis, alongside qPCR and culture titration methodologies to determine sensitivity, specificity, PPV, NPV and accuracy. Resistance was confirmed by CLSI-compliant susceptibility testing and genetic mechanisms determined. The MYCO WELL D-ONE displayed a sensitivity and specificity of 91.98% and 96.44% for the detection of Ureaplasma spp., with sensitivity and specificity values of 78.23% and 98.84% for Mycoplasma hominis, compared with qPCR. Swabs harboured significantly greater bacterial loads than urine samples for both Ureaplasma spp. and M. hominis. Levofloxacin resistance rates, mediated by Ser83Leu mutation in ParC, for Ureaplasma spp. were 0.54%. Tetracycline resistance rates, mediated by tet(M), were 0.54% and 2% for Ureaplasma spp. and M. hominis, respectively; sequence analysis of tet(M)-positive Ureaplasma spp. and M. hominis strains isolated from a single individual confirmed separate resistance gene origins. The MYCO WELL D-ONE is a sensitive and specific assay for the detection of Ureaplasma spp. and M. hominis in genitourinary medicine samples, facilitating the accurate detection of these organisms within low-technology environments. While good for antibiotic resistance screening, accurate confirmation by MIC determination or molecular methods are required, and more optimally performed on urine samples.

Prevalence, virulence and antibiotic susceptibility of Listeria monocytogenes isolated from sheep

Objective: This study was undertaken to determine the prevalence, virulence, and antibiotics susceptibility of Listeria monocytogenes isolated from hindbrain, spinal cord, milk, and intestinal content collected from sheep in the Dakahlia Governorate, Egypt. Design: Observational study. Samples: We analyzed 472 samples, including 72 hindbrain/spinal cord samples from emergency-slaughtered sheep, 300 raw-milk samples from apparently healthy sheep, and 100 intestinal content samples from slaughtered sheep at three abattoirs. Procedures: Isolation and identification of L. monocytogenes were performed using conventional techniques. The biochemically identified isolates were confirmed by 16SrRNA gene sequencing and examined for virulence-associated genes (hlyA and iap) as well as for antimicrobial susceptibility. Results: In total, 16 (3.39%) out of 472 sheep samples [5.56% (4/72) in hindbrain/spinal cord, 4% (12/300) in milk, and 0% (0/100) in intestinal content samples] were found to be positive for L. monocytogenes. All the confirmed isolates were positive for the hlyA gene (100%); meanwhile, none of them exhibited the iap gene. Antibiotic susceptibility testing showed high resistance rates to amoxicillin, cefotaxime, erythromycin (50% each), and vancomycin (37.5%). Sulfamethoxazole–trimethoprim and tetracycline resistance rates were 25% and 12.5%, respectively. On the contrary, all isolates were susceptible to amikacin, ciprofloxacin, and norfloxacin. Interestingly, 37.5% (6/16) of L. monocytogenes isolates exhibited multidrug resistance (MDR). The multiple antibiotic resistances (MAR) index of isolates ranged from 0.1 to 0.6. Conclusion and clinical relevance: Our data highlights the importance of awareness of virulent strains of MDR L. monocytogenes of sheep samples and potentially samples from other domestic animals in Egypt.

Detection of Carbapenem-Resistant Genes in Escherichia coli Isolated from Drinking Water in Khartoum, Sudan.

Waterborne Escherichia coli are a major reservoir of antimicrobial resistance (AMR). Carbapenem-resistance, especially when mediated by transferable carbapenemase-encoding genes, is spreading worldwide and causing dramatically limiting treatment options. In our country, studies for the detection of carbapenem resistance in drinking water do not exist; therefore, this work was carried out to determine the prevalence of carbapenem-resistant genes “blaKPC, blaIMP, blaNDM, blaSPM, blaVIM, and blaOXA-48” among Escherichia coli isolated from drinking water in Khartoum, Sudan. A total of forty-five E. coli bacteria were isolated from different sources of drinking water. Antimicrobial susceptibility testing was performed using imipenem (10 mg/disc), gentamicin (10 mg/disc), ceftriaxone (30 mg/disc), ciprofloxacin (5 mg/disc), chloramphenicol (30 mg/disc), and tetracycline (30 mg/disc). “Sensitive” or “resistant” patterns of E. coli were judged using antibiotic minimum inhibitory concentration (MIC). Bacterial genomic DNA was extracted by the boiling method, and then multiplex polymerase chain reaction was performed to detect the carbapenemase genes (blaKPC, blaIMP, blaNDM, blaSPM, blaVIM, and blaOXA-48). Multiplex PCR assays confirmed the presence of carbapenemase genes in 28% of all water isolates. OXA-48 gene was the most predominant gene, detected in 15.5% of the isolates. The blaKPC and blaSPM genes were also detected in 4.4% and 8.8% of the isolates, respectively. However, the isolates were negative for blaNDM, blaVIM, and blaIMP genes. The isolates showed a high rate of tetracycline resistance (97.7%), followed by gentamicin (57.7%), ciprofloxacin (46.6%), ceftriaxone (35.5%), and chloramphenicol (31.1%). In conclusion, this study confirmed for the first time the presence of E. coli carried carbapenem-resistant genes in the drinking water of Khartoum state, Sudan. These isolates commonly carried OXA-48 (7/45), followed by SPM (4/45) and KPC (2/45).

Antimicrobial Resistance in Nontyphoidal Salmonella Isolates from Human and Swine Sources in Brazil: A Systematic Review of the Past Three Decades.

Salmonella is the leading cause of foodborne illnesses worldwide. The widespread use of antimicrobials as prophylactic, therapeutic, and growth promoters in both livestock and human medicine has resulted in selective pressure regarding antimicrobial-resistant (AMR) bacteria. This systematic review summarizes phenotypic antimicrobial resistance profiles in Salmonella isolates from human and swine sources between 1990 and 2018 in Brazil. The 20 studies that matched the eligibility criteria-isolates from pigs and humans from Brazil, between 1990 and 2016, containing information on the number of Salmonella isolates, and applying the disk diffusion susceptibility method-were included. During the assessed period, Salmonella strains isolated from swine sources displayed the highest resistance rates for tetracycline (20.3%) and sulfonamides (17.4%). In contrast, human isolates displayed the highest resistance rates against ampicillin (19.8%) and tetracycline (17%). Salmonella Typhimurium was the most frequent AMR isolate from both swine and human sources, corresponding to 67% of all isolates. From 2001 to 2005, tetracycline and ampicillin were the top antimicrobial resistance compounds, and the most frequently detected in swine and human sources, respectively. A total of 63 and 58 multiple drug resistance profiles were identified in swine and human isolates, respectively. Antimicrobial resistance has decreased throughout the 1990-2016 period, except for gentamicin and nalidixic acid in swine and human isolates, respectively. The results indicate that Salmonella isolated from human and swine display resistance against clinically important antimicrobials, indicating that swine are possibly one of the main vectors for spreading human salmonellosis in Brazil.

Antibiotic-Impregnated Central Venous Catheters Do Not Change Antibiotic Resistance Patterns

Antibiotic-impregnated central venous catheters (CVCs) decrease the incidence of infection in high-risk patients. However, use of these catheters carries the hypothetical risk of inducing antibiotic resistance. We hypothesized that routine use of minocycline and rifampin-impregnated catheters (MR-CVC) in a single intensive care unit (ICU) would change the resistance profile for Staphylococcus aureus. We reviewed antibiotic susceptibilities of S. aureus isolates obtained from blood cultures in a large urban teaching hospital from 2002-2015. Resistance patterns were compared before and after implementation of MR-CVC use in the surgical ICU (SICU) in August 2006. We also compared resistance patterns of S. aureus obtained in other ICUs and in non-ICU patients, in whom MR-CVCs were not used. Data for rifampin, oxacillin, and clindamycin were available for 9,703 cultures; tetracycline resistance data were available for 4,627 cultures. After implementation of MR-CVC use in the SICU, rifampin resistance remained unchanged, with rates the same as in other ICU and non-ICU populations (3%). After six years of use of MR-CVCs in the SICU, the rate of tetracycline resistance was unchanged in all facilities (1%-3%). The use of MR-CVCs was not associated with any change in S. aureus oxacillin-resistance rates in the SICU (66% vs. 60%). However, there was a significant decrease in S. aureus clindamycin resistance (59% vs. 34%; p < 0.05) in SICU patients. Routine use of rifampin-minocycline-impregnated CVCs in the SICU was not associated with increased resistance of S. aureus isolates to rifampin or tetracyclines.

Comparing the Genetic Diversity and Antimicrobial Resistance Profiles of Campylobacter jejuni Recovered from Cattle and Humans.

Campylobacter jejuni, a leading cause of gastroenteritis in humans, is a foodborne pathogen that can reside in chickens, pigs, and cattle. Because resistance to fluoroquinolones and macrolides, which are commonly used to treat human infections, has emerged in C. jejuni, it is imperative to continously monitor resistance patterns and examine the genetic variation in strains from human infections and animal reservoirs. Our previous study of C. jejuni from human campylobacteriosis cases showed a significantly higher rate of tetracycline resistance compared to national trends, and identified multilocus sequence type (ST)-982 and a history of cattle contact to be associated with tetracycline resistance. To further investigate these associations, we conducted a cross-sectional study to determine the frequency of antimicrobial resistance and examine the genetic diversity of C. jejuni recovered from 214 cattle at three Michigan herds. Overall, the prevalence of C. jejuni was 69.2% (range: 58.6–83.8%) for the three farms, and 83.7% (n = 113) of isolates were resistant to one or more antimicrobials. Resistance to only tetracycline predominated among the cattle isolates (n = 89; 65.9%) with most resistant strains belonging to ST-459 (96.5%) or ST-982 (86.4%). Among the 22 STs identified, STs 459 and 982 were more prevalent in one feedlot, which reported the use of chlortetracycline in feed upon arrival of a new herd. PCR-based fingerprinting demonstrated that the ST-982 isolates from cattle and humans had identical banding patterns, suggesting the possibility of interspecies transmission. Resistance to macrolides (1.5%) and ciprofloxacin (16.3%) was also observed; 14 of the 22 ciprofloxacin resistant isolates represented ST-1244. Together, these findings demonstrate a high prevalence of antimicrobial resistant C. jejuni in cattle and identify associations with specific genotypes. Continuous monitoring and identification of risk factors for resistance emergence are imperative to develop novel methods aimed at decreasing pathogen persistence in food animal reservoirs and the frequency of resistant infections in humans.

Serotype Distribution, Population Structure, and Antimicrobial Resistance of Group B Streptococcus Strains Recovered from Colonized Pregnant Women.

Using serotyping, multilocus sequence typing, and whole-genome sequencing (WGS) of selected strains, we studied the population structure of 102 group B Streptococcus (GBS) isolates prospectively sampled in 2014 from vaginal/rectal swabs of healthy pregnant women in metropolitan Toronto, Canada. We also determined the susceptibilities of each of the colonizing isolates to penicillin, erythromycin, clindamycin, tetracycline, and other antimicrobial agents. Overall, we observed a high rate of tetracycline resistance (89%) among colonizing GBS isolates. We found resistance to erythromycin in 36% of the strains, and 33% were constitutively or inducibly resistant to clindamycin. The most frequently identified serotypes were III (25%), Ia (23%), and V (19%). Serotype IV accounted for 6% of the colonizing isolates, a rate consistent with that observed among patients with invasive GBS infections in metropolitan Toronto. The majority of serotype IV isolates belonged to sequence type (ST)459, a tetracycline-, erythromycin-, and clindamycin-resistant ST first identified in Minnesota, which is considered to be the main driver of serotype IV GBS expansion in North America. WGS revealed that ST459 isolates from Canada are clonally related to colonizing and invasive ST459 organisms circulating in regions of the United States. We also used WGS to study recombination in selected colonizing strains from metropolitan Toronto, which revealed multiple episodes of capsular switching. Present and future circulating GBS organisms and their genetic diversity may influence GBS vaccine development.

Faecal carriage of antibiotic resistant Escherichia coli in asymptomatic children and associations with primary care antibiotic prescribing: a systematic review and meta-analysis.

BackgroundThe faecal reservoir provides optimal conditions for the transmission of resistance genes within and between bacterial species. As key transmitters of infection within communities, children are likely important contributors to endemic community resistance. We sought to determine the prevalence of antibiotic-resistant faecal Escherichia coli from asymptomatic children aged between 0 and 17 years worldwide, and investigate the impact of routinely prescribed primary care antibiotics to that resistance.MethodsA systematic search of Medline, Embase, Cochrane and Web of Knowledge databases from 1940 to 2015. Pooled resistance prevalence for common primary care antibiotics, stratified by study country OECD status. Random-effects meta-analysis to explore the association between antibiotic exposure and resistance.ResultsThirty-four studies were included. In OECD countries, the pooled resistance prevalence to tetracycline was 37.7 % (95 % CI: 25.9–49.7 %); ampicillin 37.6 % (24.9–54.3 %); and trimethoprim 28.6 % (2.2–71.0 %). Resistance in non-OECD countries was uniformly higher: tetracycline 80.0 % (59.7–95.3 %); ampicillin 67.2 % (45.8–84.9 %); and trimethoprim 81.3 % (40.4–100 %). We found evidence of an association between primary care prescribed antibiotics and resistance lasting for up to 3 months post-prescribing (pooled OR: 1.65, 1.36–2.0).ConclusionsResistance to many primary care prescribed antibiotics is common among faecal E. coli carried by asymptomatic children, with higher resistance rates in non-OECD countries. Despite tetracycline being contra-indicated in children, tetracycline resistance rates were high suggesting children could be important recipients and transmitters of resistant bacteria, or that use of other antibiotics is leading to tetracycline resistance via inter-bacteria resistance transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1697-6) contains supplementary material, which is available to authorized users.

Use of Aeromonas spp. as General Indicators of Antimicrobial Susceptibility among Bacteria in Aquatic Environments in Thailand.

Antimicrobials are widely used, not only for treating human infections, but also for treatment of livestock and in fish farms. Human habitats in Southeastern Asian countries are located in close proximity to aquatic environments. As such, the human populations within these regions are at risk of exposure to antimicrobial resistant bacteria, and thereby disseminating antimicrobial resistance genes (ARGs). In this study, we collected water samples from 15 sites (5 sites in Chao Phraya River, 2 sites at the mouth of Chao Phraya River, 3 sites in Ta Chin River, and 5 sites at city canals) and 12 sites (6 sites at city canals; 2 sites at chicken farms; 2 sites at pig farms; and 2 samples from sites at pig farms, which were subsequently treated at a biogas plant) in Thailand in 2013 and 2014, respectively. In total, 117 Aeromonas spp. were isolated from the water samples, and these organisms exhibited various antimicrobial susceptibility profiles. Notably, there was a significant correlation between the environmental concentration of tetracyclines and the rates of tetracycline resistance in the isolated Aeromonas spp.; however, both the concentration and rates of tetracycline resistance in samples derived from pig farms were higher than those of samples harvested from other aquatic environments. These findings suggest that the high concentrations of antimicrobials observed in these aquatic environments likely select for ARGs. Furthermore, they indicate that Aeromonas spp. comprise an effective marker for monitoring antimicrobial resistance in aquatic environments.

Helicobacter pylori antibiotic susceptibility patterns in Bangladesh: Emerging levofloxacin resistance.

The most recent study to report Helicobacter pylori antibiotic resistance rates in Bangladesh was published 15 years ago and did not include levofloxacin. We therefore aimed to determine the current antibiotic susceptibility of H. pylori to amoxicillin, clarithromycin, metronidazole, tetracycline and levofloxacin in Bangladesh. This study included 133 consecutive patients who underwent endoscopy examination at Dhaka Medical College in November 2014. The serial two-fold agar dilution method was used to determine the minimum inhibitory concentrations of the five antibiotics. Among 56 cultured strains, H. pylori showed high rates of resistance to clarithromycin and metronidazole (39.3% and 94.6%, respectively). Moreover, levofloxacin showed an emerging antimicrobial resistance pattern (66.1%), which was higher in patients with gastritis than that in those with peptic ulcers (p = 0.02). The resistance rate of levofloxacin was significantly higher in patients living in Dhaka city compared to those living in the village (p = 0.049). However, amoxicillin and tetracycline resistance rates were very low. Resistance to both metronidazole and levofloxacin was most commonly observed. The rates of resistance to clarithromycin, metronidazole, and levofloxacin were high in Bangladesh, which suggests that triple therapy based on these drugs may not be useful as first-line therapies in Bangladesh. Alternative strategies such as furazolidone-based triple therapy, bismuth-based quadruple therapies, or sequential therapy may be more effective for patients in in Bangladesh.

The Changing Profile of Helicobacter pylori Antibiotic Resistance in Singapore: A 15-Year Study.

Antibiotic resistance is an important cause of H. pylori treatment failure. This study aimed to examine the change in H. pylori antibiotic resistance profile in Singapore over the course of 15 years. The study period was from 2000 to 2014. Gastric mucosal biopsies obtained from H. pylori-positive patients were cultured. Antibiotic susceptibility to metronidazole, clarithromycin, levofloxacin, tetracycline, and amoxicillin was tested. The change in resistance rates over time was analyzed. A total of 708 H. pylori isolates were cultured. There was a significant increase in resistance rates for metronidazole (2000-2002: 24.8%; 2012-2014: 48.2%; p < .001), clarithromycin (2000-2002: 7.9%; 2012-2014: 17.1%; p = .022), and levofloxacin (2000-2002: 5%; 2012-2014: 14.7%; p = .007). The resistance rates for tetracycline (2000-2002: 5%; 2012-2014: 7.6%) and amoxicillin (2000-2002: 3%; 2012-2014: 4.4%) remained stable. Increase in dual (2000-2002: 6.9%; 2012-2014: 9.4%; p = .479) and triple antibiotic resistance rates (2000-2002: 0; 2012-2014: 7.6%; p < .001) were observed. Overall, the most common dual and triple resistance patterns were metronidazole/clarithromycin (4.4%) and metronidazole/clarithromycin/levofloxacin (1.8%), respectively. Over 15 years, H. pylori resistance rates to metronidazole, clarithromycin and levofloxacin had increased. There was increased resistance to multiple antibiotics.

Antimicrobial susceptibility, virulence determinant carriage and molecular characteristics of Staphylococcus aureus isolates associated with skin and soft tissue infections

A better understanding of the antimicrobial susceptibility, carriage of virulence determinants and molecular characteristics of Staphylococcus aureus isolates associated with skin and soft tissue infections (SSTIs) may provide further insights related to clinical outcomes with these infections. From January 2012 to September 2013, a total of 128 non-duplicate S. aureus isolates were recovered from patients with SSTIs. All 128 S. aureus SSTI isolates carried at least five virulence genes tested. Virulence genes detected among at least 70% of all tested isolates included hld (100%), hla (95.3%), icaA (96.9%), clf (99.2%), sdrC (79.7%), sdrD (70.3%), and sdrE (72.7%). The prevalence of MRSA isolates with 10 virulence genes tested (54.4%, 31/56) was significantly higher than that among MSSA isolates (35.2%, 25/71) (p<0.05). The positive rates of seb, sen, sem, sdrE and pvl among MRSA isolates were significantly higher than among MSSA isolates (p<0.05). ST7 and ST630 accounting for 10.9% were found to be the predominant STs. The most prevalent spa type was t091 (8.6%). MRSA-ST59-SCCmec IV was the most common clone (12.3%) among MRSA isolates whereas among MSSA isolates the dominant clone was MSSA-ST7 (15.5%). Six main clonal complexes (CCs) were found, including CC5 (52.3%), CC7 (11.7%), CC59 (8.6%), CC88 (6.3%), CC398 (4.7%), and CC121 (3.1%). A higher carriage of seb and sec was found among CC59 isolates. In comparison to CC5 and CC7 isolates, those with the highest carriage rates (>80.0%) of sdrC and sdrD, CC59 isolates had lower prevalence of these two virulence genes. All CC59 isolates were susceptible to gentamicin and trimethoprim/sulfamethoxazole, while CC5 and CC7 isolates had resistance rates to these two antimicrobials of 25.4% and 20.9%, and 40.0% and 40.0%, respectively. The resistance rates for tetracycline, clindamycin, and erythromycin among CC5 isolates were lower than among CC7 and CC59 isolates. In conclusion, the molecular typing of S. aureus SSTI isolates in the present study showed considerable heterogeneity. ST7 and ST630 became prevailing clones. Different S. aureus clones causing SSTIs were associated with specific antimicrobial resistance and virulence gene profiles.

Antimicrobial resistance, virulence factors and genetic lineages of hospital-onset methicillin-resistant Staphylococcus aureus isolates detected in a hospital in Zaragoza

IntroductionMRSA population dynamics is undergoing significant changes, and for this reason it is important to know which clones are circulating in our nosocomial environment. Materials and methodsA total of 118 MRSA isolates were collected from clinical samples from patients with previous hospital or healthcare contact (named as hospital-onset MRSA (HO-MRSA)) during a one year period. Susceptibility testing was performed by disk diffusion and microdilution. The presence of resistance genes and virulence factors were tested by PCR. All isolates were typed by SCCmec, spa and agr typing. PFGE and MLST were applied to a selection of them. ResultsEighty-three HO-MRSA isolates (70.3%) were resistant to any antibiotic included in the macrolide–lincosamide–streptogramin B group. Among these isolates, the M phenotype was the most frequent (73.5%). One hundred and seven of HO-MRSA isolates (90.7%) showed aminoglycoside resistance. The combination aac(6′)-Ie-aph(2″)-Ia+ant(4′)-Ia genes was the most frequent (22.4%). Tetracycline resistance rates in HO-MRSA isolates were low (3.4%), although a high level of mupirocin resistance was observed (25.4%). Most of the HO-MRSA isolates (approximately 90%) showed SCCmec type IVc and agr type II. Fifteen unrelated pulsotypes were identified. CC5 was the most prevalent (88.1%), followed by CC8 (5.9%), CC22 (2.5%), CC398 (2.5%) and CC1 (0.8%). ConclusionCC5/ST125/t067 lineage was the most frequent. This lineage was related to aminoglycoside resistance, and to a lesser extent, with macrolide resistance. The presence of international clones as EMRSA-15 (CC22/ST22), European clones as CC5/ST228, community clones related to CC1 or CC8 and livestock associated clones, as CC398, were observed in a low percentage.

Molecular epidemiology of Staphylococcus aureus in post-earthquake northern Haiti

Knowledge of nasal carriage is important in predicting staphylococcal infection, and no information exists regarding the endemicity of Staphylococcus aureus in Haiti. We performed a cross-sectional analysis of S. aureus nasal screening in an acute care, a subacute rehabilitation, and a community setting, with a brief medical and epidemiological history. PCR-positive S. aureus screening nasal cultures underwent molecular analysis for spa type, SCCmec type, and virulence genes (Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin (TSST), and arginine catabolic mobile element (ACME)), and were evaluated for antibiotic susceptibility using commercial tests. Overall carriage rates of 8.4% methicillin-susceptible S. aureus (MSSA) and 2.8% methicillin-resistant S. aureus (MRSA) were identified, with a high rate of tetracycline resistance. TSST and PVL genes were identified in MSSA. MRSA isolates contained no virulence markers. Unique MSSA phenotypes (i.e., linezolid-resistant, vancomycin-sensitive/daptomycin non-susceptible) were identified, as were two PVL-positive ST152 MSSA colonization isolates, previously geographically limited to Africa. We found a low S. aureus carriage rate with complete vancomycin susceptibility and high tetracycline resistance, which has important public health implications with regard to treatment. Additionally, the finding of PVL-positive MSSA isolates, including the expansion of a previously described limited 'divergent' clone, ST152, warrants further evaluation.

Clone wars: Let's pick out the superbugs

Antibiotic Resistance Since the 1960s, group B streptococci (GBS) have lost genetic diversity, yet they cause more virulent neonatal infections and show high rates of tetracycline resistance. The puzzle is that tetracycline is not used to treat GBS. Nevertheless, since the 1950s, most GBS clones were wiped out by the collateral effects of the widespread use of tetracycline and other antibiotics, even though they were not the treatment target. Da Cunha et al. show that a few GBS clones survived by virtue of their persistence or virulence, and these clones also acquired mobile genetic elements carrying a mixture of antibiotic resistance genes, including those for tetracycline resistance. Nat. Comm. 10.1038/ncomms5544 (2014).