Isolation Of Antibiotic-resistant Bacteria Research Articles

Analyzing Antibiotic Resistance in Bacteria from Wastewater in Pakistan Using Whole-Genome Sequencing.

Background: Wastewater is a major source of Antibiotic-Resistant Bacteria (ARB) and a hotspot for the exchange of Antibiotic-Resistant Genes (ARGs). The occurrence of Carbapenem-Resistant Bacteria (CRB) in wastewater samples is a major public health concern. Objectives: This study aimed to analyze Antibiotic resistance in bacteria from wastewater sources in Pakistan. Methods: We analyzed 32 bacterial isolates, including 18 Escherichia coli, 4 Klebsiella pneumoniae, and 10 other bacterial isolates using phenotypic antibiotic susceptibility assay and whole-genome sequencing. This study identified the ARGs, plasmid replicons, and integron genes cassettes in the sequenced isolates. One representative isolate was further sequenced using Illumina and Oxford nanopore sequencing technologies. Results: Our findings revealed high resistance to clinically important antibiotics: 91% of isolates were resistant to cefotaxime, 75% to ciprofloxacin, and 62.5% to imipenem, while 31% showed non-susceptibility to gentamicin. All E. coli isolates were resistant to cephalosporins, with 72% also resistant to carbapenems. Sequence analysis showed a diverse resistome, including carbapenamases (blaNDM-5, blaOXA-181), ESBLs (blaCTX-M-15, blaTEM), and AmpC-type β-lactamases (blaCMY). Key point mutations noticed in the isolates were pmrB_Y358N (colistin) and ftsI_N337NYRIN, ftsI_I336IKYRI (carbapenem). The E. coli isolates had 11 different STs, with ST410 predominating (28%). Notably, the E. coli phylogroup A isolate 45EC1, (ST10886) is reported for the first time from wastewater, carrying blaNDM-5, blaCMY-16, and pmrB_Y358N with class 1 integron gene cassette of dfrA12-aadA2-qacEΔ1 on a plasmid-borne contig. Other carbapenamase, blaNDM-1 and blaOXA-72, were detected in K. pneumoniae 22EB1 and Acinetobacter baumannii 51AC1, respectively. The integrons with the gene cassettes encoding antibiotic resistance, and the transport and bacterial mobilization protein, were identified in the sequenced isolates. Ten plasmid replicons were identified, with IncFIB prevalent in 53% of isolates. Combined Illumina and Oxford nanopore sequencing revealed blaNDM-5 on an IncFIA/IncFIC plasmid and is identical to those reported in the USA, Myanmar, and Tanzania. Conclusions: These findings highlight the environmental prevalence of high-risk and WHO-priority pathogens with clinically important ARGs, underscoring the need for a One Health approach to mitigate ARB isolates.

Dissemination of antibiotic resistance genes from aboveground sources to groundwater in livestock farms

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are prevalent in various environments on livestock farms, including livestock waste, soil, and groundwater. Contamination of groundwater by ARB and ARGs in livestock farms is a growing concern as it may have potentially huge risks to human health. However, the source of groundwater-borne ARB and ARGs in animal farms remains largely unknown. In this study, different types of samples including groundwater and its potential contamination sources from aboveground (pig feces, wastewater, and soil) from both working and abandoned swine feedlots in southern China were collected and subjected to metagenomic sequencing and ARB isolation. The source tracking based on metagenomic analysis revealed that 56–95 % of ARGs in groundwater was attributable to aboveground sources. Using metagenomic assembly, we found that 45 ARGs predominantly conferring resistance to aminoglycosides, sulfonamides, and tetracyclines could be transferred from the aboveground sources to groundwater, mostly through plasmid-mediated horizontal gene transfer. Furthermore, the full-length nucleotide sequences of sul1, tetA, and TEM-1 detected in ARB isolates exhibited the close evolutionary relationships between aboveground sources and groundwater. Some isolated strains of antibiotic-resistant Pseudomonas spp. from aboveground sources and groundwater had the high similarity (average nucleotide identity > 99 %). Notably, the groundwater-borne ARGs were identified as mainly carried by bacterial pathogens, potentially posing risks to human and animal health. Overall, this study underscores the dissemination of ARGs from aboveground sources to groundwater in animal farms and associated risks.

Impact of soil supplemented with pig manure on the abundance of antibiotic resistant bacteria and their associated genes.

This study was conducted to evaluate the abundance of antibiotic resistant bacteria and their resistance genes from agriculture soil supplemented with pig manure. Uncultivable soil sample was supplemented with pig manure samples under microcosm experimental conditions and plated on Luria-Bertani (LB) agar incorporated with commercial antibiotics. The supplementation of soil with 15% pig manure resulted in the highest increase in the population of antibiotic resistant bacteria (ARB)/multiple antibiotic resistant bacteria (MARB). Seven genera that included Pseudomonas, Escherichia, Providencia, Salmonella, Bacillus, Alcaligenes and Paenalcaligenes were the cultivable ARB identified. A total of ten antibiotic resistant bacteria genes (ARGs) frequently used in clinical or veterinary settings and two mobile genetic elements (MGEs) (Class 1 and Class 2 integrons) were detected. Eight heavy metal, copper, cadmium, chromium, manganese, lead, zinc, iron, and cobalt were found in all of the manure samples at different concentrations. Tetracycline resistance genes were widely distributed with prevalence of 50%, while aminoglycoside and quinolone-resistance gene had 16% and 13%, respectively. Eighteen ARB isolates carried more than two ARGs in their genome. Class 1 integron was detected among all the 18 ARB with prevalence of 90-100%, while Class 2 integron was detected among 11 ARB. The two classes of integron were found among 10 ARB. Undoubtedly, pig manure collected from farms in Akure metropolis are rich in ARB and their abundance might play a vital role in the dissemination of resistance genes among clinically-relevant pathogens.

Bacterial Assessment and Isolation of Antibiotic Resistant Bacteria from the Indian Major Carp, Labeo rohita

A bacteriological study of fish is critical to protecting people from potential hazards and serving as an indicator of water contamination. The study was carried out to investigate microorganisms from the Labeo rohita. A total bacterial load was measured in the skin, gills, and intestine. It had a total bacterial load (TBL) of 1.54×109 CFU/g on average. The intestine had the highest average TBL of 2.09×109 CFU/g, while the gill had the lowest average TBL of 1.08×109 CFU/g. Isolated bacteria were grouped based on colony characteristics and then subjected to morphological, physiological, and biochemical analysis for identification up to the genus or species level. Staphylococcus aureus and Vibrio spp. were identified as the two microorganisms. After a thorough examination and PCR analysis, the two bacteria, S. aureus and Vibrio spp., were isolated. S. aureus was detected in skin samples from R3 and R5 fish. S. aureus was isolated from R3, R4, and R5 in the gills. S. aureus was found in intestinal samples R2, R3, R4, and R5. The presence of Vibrio spp. was found in the intestines of all fish samples tested, as well as the skin of R4 and R5, and the gills of R2, R3, R4, and R5. The 16S rRNA gene was amplified in all S. aureus isolates, while the Tox-R gene was amplified in all Vibrio spp isolates. The isolated S. aureus and Vibrio tested positive for the 16s rRNA and Tox-R genes, respectively. An antibiotic sensitivity test revealed that the majority of S. aureus and Vibrio spp were susceptible to azithromycin, ciprofloxacin, and tetracycline but resistant to amoxicillin and streptomycin.

Detection of antibiotic resistance in bacteria isolated from industrial sewage

Industrialization and indiscriminate discharge of sewage being implicated in environmental pollution is responsible for the release of micropollutants which over time is expected to alter the physiology and metabolic pathways of microbiota native to the environment. This study was undertaken to track antibiotic resistant genes in industrial wastewater. Heterotrophic bacterial count indicated a vast abundance of culturable bacteria (76-232.66× 104 Cfu/ml). Hydrocarbon utilizing bacteria count ranged between (91.66 - 111.6×104 Cfu/ml). Antibiotic resistant bacteria isolates from industrially impacted wastewater identified by Sanger’s sequencing included Bacillus lichenforminis (KF737353.1), Alkanindiges sp. 5-0-9 (LT158291.1), Bacillus thuringiensis (MK875170.1, MK517632.1 EU697392.1) Bacillus altitudinis (KY777585.1), Bacillus cereus (KR185830.1) and Bacillus subtilis (MK124647.1). This study infers that industrial effluent is a potent reservoir for antibiotic resistant bacteria of environmental and public health concerns.

Antibiotic use in commercial broiler chicken farming and its consequential resistance development in root colonizing bacteria of carrot grown in manure-applied soils in a middle-income country

Broiler chicken litter (BCL) is a cheap manure for vegetable crops in developing countries. Extensive antibiotic use in poultry production could increase antibiotic resistant bacteria (ARB) in manure and eventually in crop root microbiome. We investigated the prevalence of ARB in BCL from medium- and large-scale farms (n = 33) and in carrot (Daucus carota) grown in BCL-applied soils in Sri Lanka. All the BCL samples contained aerobic bacteria resistant to 10 μg·mL−1 of oxytetracycline or enrofloxacin. The abundance of ARB determined by viable plate-count method ranged from 0.05% to 30.10% of aerobic bacterial population. Soil from two fields applied with BLC for 3 yr (short history, SH) and 10 yr (long history, LH) were treated with BCL (10%, w/w) and oxytetracycline (10 and 100 mg·kg−1) in a pot experiment alongside an unamended control. Adding BCL and oxytetracycline had a significant (P < 0.05) effect on the abundance of oxytetracycline-resistant epiphytic and endophytic bacteria (EEB) in carrot roots at harvest. Both total and oxytetracycline-resistant EEB increased significantly (P < 0.05) with the application of BCL to LH soil but not to SH soil. Carrot sold at retailed markets (n = 30) contained epiphytic bacteria resistant to 1 μg·mL−1 oxytetracycline (4.13 ± 0.207 log10CFU·g−1 dry carrot). High minimum inhibitory concentrations for oxytetracycline (≥128 μg·mL−1) were observed in 83% and 50% of ARB isolates obtained from BCL (n = 18) and carrot (n = 24), respectively. Results confirmed that BCL acts as a carrier of ARB, and continuous application of BCL to soil increased the prevalence of ARB among EEB in carrot.

Urinary lead level and colonization by antibiotic resistant bacteria: Evidence from a population-based study.

Infection by antibiotic resistant bacteria (ARB) is a global health crisis and asymptomatic colonization increases risk of infection. Nonhuman studies have linked heavy metal exposure to the selection of ARB; however, few epidemiologic studies have examined this relationship. This study analyzes the association between urinary lead level and colonization by ARB in a nonclinical human population. Data came from the Survey of the Health of Wisconsin 2016-2017, and its ancillary Wisconsin Microbiome Study. Urinary lead levels, adjusted for creatinine, were used to assess exposure. ARB included methicillin resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), fluoroquinolone resistant Gram-negative bacilli (RGNB), and Clostridium difficile (C. diff), from skin, nose, and mouth swabs, and saliva and stool samples. Logistic regression, adjusted for covariates, was used to evaluate associations between Pb and ARB. Secondary analysis investigated Pb resistance from ARB isolates. Among 695 participants, 239 (34%) tested positive for ARB. Geometric mean urinary Pb (unadjusted) was 0.286 µg/L (95% confidence intervals [CI] = 0.263, 0.312) for ARB negative participants and 0.323 µg/L (95% CI = 0.287, 0.363) for ARB positive participants. Models adjusted for demographics, diet, and antibiotic use showed elevated odds of positive colonization for those in the 95th percentile (vs. below) of Pb exposure (odds ratio [OR] = 2.05, 95% CI = 0.95, 4.44), and associations were highest in urban residents (OR = 2.85, 95% CI = 1.07, 7.59). RGNB isolates were most resistant to Pb. These novel results suggest that Pb exposure is associated with increased colonization by ARB, and that RGNB are particularly resistant to Pb.

Isolation of Antibiotic Resistant Bacteria from Rivers in Kelantan, Malaysia

Antibiotic resistant bacteria have been a major concern due to the problems that they may pose in terms of public and environmental health. This present study aimed to investigate the presence of antibiotic resistance among bacterial strains isolated from rivers and to determine the impact of various human activities on the distribution of antibiotic resistant bacteria. Bacteria were isolated from river water samples of Lebir River (Point 1 and Point 2) and Kelantan River (Point 3 and Point 4). Antibiotic susceptibility test was conducted on the bacterial isolates against six types of antibiotics (ampicillin, gentamycin, tetracycline, chloramphenicol, rifampicin and ciprofloxacin) was performed, followed by characterization and identification of the isolates using a series of biochemical tests. The findings show the presence of antibiotic resistant bacteria in all four samples, indicating the relationship between the resistance of isolates and the human activities within the vicinity of the area. A total of 27 bacterial isolates were successfully isolated from the rivers and predicted as Actinomyces sp., Arachnia sp., Streptomyces sp., Streptococcus sp., Enterococcus sp., Bacillus sp., Clostridium sp., Neisseria sp., Veillonella sp., Bacteroides sp., Salmonella sp., Shigella sp., Proteus sp., Enterobacter sp., Klebsiella sp., Escherichia sp, Pseudomonas sp., Aeromonas sp., Vibrio sp. Staphylococcus sp., Micrococcus sp., Actinobacillus sp., and Flavobacterium sp. However, further analysis of the antibiotic resistant bacteria is recommended to further identify and understand them due to the potential risk that they may pose to human and environment.

Isolation of Antibiotic Resistant Bacteria from Rivers in Terengganu, Malaysia

Infectious disease cause by antibiotic resistant bacteria has been more difficult to treat because the ability of these bacteria to avoid the effect of antibiotic medication. Nowadays, water environment especially river has become the reservoir for the dissemination of antibiotic resistant bacteria due to antibiotic contamination derived from human activities. The exposure to antibiotic resistance bacteria in water increase the health risks associated with the waterborne bacteria in animals and humans. Therefore, this study was carried out to investigate the presence of antibiotic resistant bacteria from two rivers in Terengganu; Ibai River and Terengganu River. A total of 24 bacterial strains were isolated from both rivers. Antibiotic susceptibility of the bacteria isolates were assayed according to the Kirby-Bauer disk diffusion method using six types of antibiotics; ampicillin, rifampicin, gentamicin, tetracycline, ciprofloxacin and chloramphenicol. The results of this study indicate that 100% of bacterial strains were resistant to at least two antibiotics tested. The multiple antibiotic resistant (MAR) index of these bacteria was calculated and 23 bacterial strains show MAR index of more than 20%. These bacteria were selected for further characterization using 16S rRNA gene sequencing. Among the 23 isolates, a total of 10 bacterial strains (2A, 2B, 2C, 2I, 3A, 3B, 4A, 4C, 4D and 4E) were successfully identified as Chromobacterium violaceum, Enterobacter tabaci, Bacillus wiedmannii, Acinetobacter baumannii, Klebsiella quasipneumoniae subsp. quasipneumoniae, Chromobacterium aquaticum, Cupriavidus metallidurans, Weeksella massiliensis, Cupriavidus necator and Acinetobacter nosocomialis. The results from this study show that both of the rivers are exposed to high level of antibiotics compound which may lead the bacteria to develop mechanism of antibiotic resistant. This may cause a serious threat to the public health and environment.

Isolation of antibiotic-resistant bacteria in biogas digestate and their susceptibility to antibiotics

Antibiotics are widely used to prevent and treat diseases and promote animal growth in the livestock industry, and therefore antibiotic residues can end up in biogas digestate from processes treating animal manure (AM) and food waste (FW). These digestates represent a potential source of spread of antimicrobial resistance (AMR) when used as fertilisers. This study evaluated AMR risks associated with biogas digestates from two processes, using AM and FW as substrate, by isolation and identification of antibiotic-resistant bacteria (ARB) and testing their susceptibility to different antibiotics. ARB from the digestates were isolated by selective plating. The antibiotic susceptibility profile of isolates was determined using ampicillin, ceftazidime, meropenem, vancomycin, ciprofloxacin, rifampicin, chloramphenicol, clindamycin, erythromycin, tetracycline, gentamicin or sulfamethoxazole/trimethoprim, representing different antibiotic classes with differing mechanisms of action. In total, 30 different bacterial species belonging to seven genera were isolated and classified. Bacillus and closely related genera, including Paenibacillus, Lysinibacillus and Brevibacillus, were the dominant ARB in both digestates. Most of the ARB strains isolated were non-pathogenic and some were even known to be beneficial to plant growth. However, some were potentially pathogenic, such as an isolate identified as Bacillus cereus. Many of the isolated species showed multi resistance and the AM digestate and FW digestate both contain bacterial species resistant to all antibiotics tested here, except gentamicin. A higher level of resistance was displayed by the FW isolates, which may indicate higher antibiotic pressure in FW compared with AM digestate. Overall, the results indicate a risk of AMR spread when these digestates are used as fertiliser. However, most of the ARB identified are species commonly found in soil, where AMR in many cases is abundant already, so the contribution of digestate-based fertiliser to the spread of AMR may still be very limited.

Bacterial quality of groundwater downgradient of onsite wastewater disposal systems and the influence on eastern Long Island's embayments.

Onsite wastewater disposal systems (OWDS) can introduce bacterial and chemical contaminants, via groundwater, into aquifers and adjacent waterways. We evaluated the concentration of fecal indicator bacteria (FIB) and antibiotic resistant bacteria (ARB) in the shallow groundwater of Eastern Long Island, New York, downgradient of OWDS using cultivation approaches and analysis of 16 S rRNA genes. While FIB and ARB were detected in 80% and 67% of groundwater samples, respectively, concentrations were low, suggesting that, at least at the time of sampling, groundwater was not a large-scale source of fecal bacterial contamination to adjacent embayments. ARB isolates did not include common fecal associated genera and the concentration of FIB and ARB did not correlate well with the concentration of pharmaceutical contaminants, suggesting that bacterial contaminants were poorly linked to OWDS discharge. Concentrations of FIB in the studied embayments were significantly greater in nearshore compared to mid-channel environments, suggesting that land-based sources are likely to be the major contributors of bacterial contamination.

Molecular profiling of multidrug-resistant river water isolates: insights into resistance mechanism and potential inhibitors.

Polluted waters are an important reservoir for antibiotic resistance genes and multidrug-resistant bacteria. This report describes the microbial community, antibiotic resistance genes, and the genetic profile of extended spectrum β-lactamase strains isolated from rivers at, Pune, India. ESBL-producing bacteria isolated from diverse river water catchments running through Pune City were characterized for their antibiotic resistance. The microbial community and types of genes which confer antibiotic resistance were identified followed by the isolation of antibiotic-resistant bacteria on selective media and their genome analysis. Four representative isolates were sequenced using next generation sequencing for genomic analysis. They were identified as Pseudomonas aeruginosa, Escherichia coli, and two isolates were Enterobacter cloacae. The genes associated with the multidrug efflux pumps, such as tolC, macA, macB, adeL, and rosB, were detected in the isolates. As MacAB-TolC is an ABC type efflux pump responsible for conferring resistance in bacteria to several antibiotics, potential efflux pump inhibitors were identified by molecular docking. The homology model of their MacB protein with that from Escherichia coli K12 demonstrated structural changes in different motifs of MacB. Molecular docking of reported efflux pump inhibitors revealed the highest binding affinity of compound MC207-110 against MacB. It also details the potential efflux pump inhibitors that can serve as possible drug targets in drug development and discovery.

Enhanced inactivation of antibiotic-resistant bacteria isolated from secondary effluents by g-C3N4 photocatalysis.

The extensive use of antibiotics has resulted in the development of antibiotic-resistant bacteria (ARB), which may not be completely removed by traditional wastewater treatment processes. More effective approaches to disinfection are needed to prevent the release of ARB into the surface water. The metal-free photocatalyst graphitic carbon nitride (g-C3N4) has aroused great interest as a possible agent for water and wastewater treatment, due to its low cytotoxicity and photoactivity with visible light. In this study, the efficacy of g-C3N4 was assessed as a possible means to enhance ARB inactivation by irradiation. ARB were isolated and purified from secondary effluents in 4 municipal wastewater treatment plants. Of these, 4 typical multi-drug ARB isolates, belonging to Enterobacteriaceae, were selected for irradiation experiments. Inactivation was seen to increase with irradiation time. At 60min, the inactivation of the 4 ARB isolates by light at > 300nm and > 400nm was in the range of 0.25-0.39 log and 0.16-0.19 log, respectively. The use of g-C3N4-mediated photocatalysis at the same wavelengths significantly enhanced that to 0.64-1.26 log and 0.31-0.41 log, respectively. The antibiotic susceptibility of the ARB isolates remained unchanged either prior to or after irradiation and was independent of photon fluence, reaction time, and the presence of g-C3N4. This study establishes a baseline for understanding the effectiveness of g-C3N4 photocatalysis on inactivation of ARB in wastewaters and lays the foundation for further improvement in the use of photocatalysis for wastewater treatment.

Exploring microbial community structure and biological function in manured soil during ten repeated treatments with chlortetracycline and ciprofloxacin

The changes of enzyme activities, microbial community structure and function, and the diversity and resistance level of antibiotic-resistant bacteria (ARB) were studied in soil during ten repeated treatments with chlortetracycline (CTC) and/or ciprofloxacin (CIP) together with organic manure (OM) under laboratory conditions. The activities of neutral phosphatase (NPA) and catalase (CAT) displayed the suppression-recovery-stimulation trend in the OM&CTC treatment but the stimulation trend in the OM&CTC&CIP treatment. The NPA was stimulated but the CAT was little affected in the OM&CIP treatment. Soil microbial functional diversity displayed the suppression-recovery-stimulation trend in the OM&CTC and OM&CTC&CIP treatments and the stimulation-suppression trend in the OM&CIP treatment with the treatment frequency. Metagenomic analysis showed that the relative abundances of Actinobacteria and Firmicutes in the antibiotic treatment significantly increased by 0.5–235.6%, but that of Proteobacteria decreased by 0.2–27.3% compared to the control with the treatment frequency. Furthermore, the relative abundances of dominant bacterial genera including Streptomyces, Actinomadura, Mycobacterium, and Streptococcus in the antibiotic treatment significantly increased by 1.1–10433.3% compared to the control. Meanwhile, repeated antibiotic treatments induced a significant increase in the diversity and resistance level of ARB isolates, especially in the OM&CTC treatment. It is concluded that repeated treatments with CTC and/or CIP can alter enzyme activities, microbial community structure and function, and increase the diversity and resistance level of ARB isolates.

Fluoroquinolone Restriction as an Effective Antimicrobial Stewardship Intervention.

Fluoroquinolones are a commonly prescribed antibiotic class that has come under scrutiny in recent years due to mounting evidence of association between adverse drug events, C. difficile infection and isolation of antibiotic-resistant bacteria. Inpatient antimicrobial stewardship (AMS) programs have a toolbox of potential interventions to curb inappropriate antibiotic use, prevent antibiotic-associated adverse drug events, and avoid unnecessary costs of care. Fluoroquinolone restriction policies in the acute care setting have demonstrated beneficial effects, including decreased rates of C. difficile infection and ESBL-producing Enterobacteriaceae. However, a simple blanket restriction policy may "squeeze the antibiotic balloon" and will likely be insufficient if not implemented in conjunction with other AMS interventions. There is a growing body of evidence to support formulary restriction of fluoroquinolones in the acute care setting to decrease rates of C. difficile infection and development of ESBL-producing organisms. Data on how to best implement these restrictions or how to implement outside of acute care settings is limited.

The influence of the autochthonous wastewater microbiota and gene host on the fate of invasive antibiotic resistance genes

The aim of this study was to assess the fate of invasive antibiotic resistance genes (ARG) discharged in wastewater. With this objective, antibiotic resistant bacteria (ARB) known to harbor specific ARG were inoculated in wastewater (hospital effluent, or municipal raw and treated wastewater) and in ultra-pure sterile water microcosms. Two sets of wastewater ARB isolates were used - set 1, Enterococcus faecalis, Acinetobacter johnsonii, Klebsiella pneumoniae and set 2, Enterococcus faecium, Acinetobacter johnsonii, Escherichia coli. Non-inoculated controls were run in parallel. Samples were collected at the beginning and at the end (15days) of the incubation period and the abundance of the genes 16S rRNA, intI1, blaTEM and vanA and the bacterial community composition were analyzed.In general, the genes blaTEM and vanA had lower persistence in wastewater and in ultra-pure water than the genes 16S rRNA or the class 1 integron integrase intI1. This effect was more pronounced in wastewater than in ultra-pure water, evidencing the importance of the autochthonous microbiota on the elimination of invasive ARG. Wastewater autochthonous bacterial groups most correlated with variations of the genes intI1, blaTEM and vanA were members of the classes Gammaproteobacteria, Bacilli or Bacteroidia. For blaTEM, but not for vanA, the species of the ARB host was important to determine its fate. These are novel findings on the ecology of ARB in wastewater environments.

Invitro and invivo antibacterial evaluation and mechanistic study of ornithine based small cationic lipopeptides against antibiotic resistant clinical isolates.

We investigated the invitro activities of short lipopeptides against a large panel of clinical isolates of antibiotic resistant bacteria. In the animal model, LP16 (5mg/kg) significantly decreased the burden of viable colony forming unit (CFU) of bacteria. MTT assay results revealed the high selectivity of lipopeptides toward microbial cells. Calcein dye leakage experiments and flow cytometric analysis suggests the membranolytic effect of lipopeptides, which was further confirmed by visualizing bacterial damage via electron microscopy tool (SEM & TEM). Moreover, stability in human blood plasma and no sign of resistance development against clinical isolates of Escherichia coli and Staphylococcus aureus were observed for lead lipopeptides. These results demonstrate the potential of short lipopeptides as a novel class of anti-infectives.

Gram-Positive Bacteria Isolated from the Common Bed Bug,Cimex lectulariusL

The common bed bug, Cimex lectularius L., is an obligate blood-feeding ectoparasite that readily feeds on humans, resulting in rashes, dermatitis, and psychological distress. Bed bug populations have increased exponentially in the last twenty years due to increased pesticide resistance and international travel. Despite their blood-feeding and ubiquity in human habitations, bed bugs are not vectors of any known pathogen. Recent isolates of antibiotic resistant bacteria from bed bugs in a homeless shelter prompted us to identify bacteria from bed bugs in low-income housing in Maryland and Colorado and from a laboratory colony, commonly known as the Harlan strain. Using standard bacteriological techniques and amplification of the 16s ribosomal RNA (rRNA) gene, four species of Gram-positive bacteria were identified from surface swabs and whole body homogenates of bed bugs. Staphylococcus arlettae and Staphylococcus epidermidis were identified from the Harlan strain; Micrococcus and Kocuria kristinae were identified from the Colorado samples. Micrococcus species have been previously identified from bed bugs, but this is the first report of K. kristinae, S. epidermidis, and S. arlettae from this insect. As an internal control for the 16s rRNA amplification, a sequence specific to Wolbachia, the bacterial endosymbiont commonly found in bed bugs, was amplified. Using these techniques, no bacteria from the gut contents were isolated. Bacteria found commonly on human skin are closely associated with bed bugs and do not pose a risk to human health. Despite their habitats and blood-feeding behavior, bed bugs from these sites were devoid of pathogenic aerobic bacteria. The mechanisms underlying bed bug resistance to exogenous bacterial infection merit further investigation.

Antibiotic sensitivity of bacteria isolated from aprons of beef vendors in Port Harcourt, Nigeria

Antibiotic (n=8) sensitivity of the bacteria isolated from twenty aprons samples of meat (beef) vendors before and after commencement of sale in a community market in Port Harcourt was assessed. Total culturable bacterial count (TCBC) before sales and during sales ranged from 50 to 80 and 35 to 6.2×102 cfu/cm2, respectively. The isolated bacteria were identified as Escherichia coli (26.51%), Staphylococcus aureus(14.46%), Bacillus sp. (22.89%), Salmonella sp. (12.05%), Proteus sp. (8.43%),Pseudomonas sp. (9.64) and Enterobacter sp. (6.02%). The isolates obtained before commencement of sale were generally more resistant than those obtained during sales. Proportion of antibiotic resistant isolates before and during sale ranged from 2.38 to 73.81 and 0 to 53.85%, respectively, while proportion of susceptibility before and during sale ranged from 14.28 to 92.86 and 39.02 to 95.12%, respectively. Isolation of antibiotic resistant bacteria from aprons of meat vendors suggests a need for an improved apron sanitization. Key words: Antibiotics, apron, beef, meat, vendor.

Extended Spectrum-β-Lactamase or Carbapenemase Producing Bacteria Isolated from Patients with Acute Cholangitis

Background/AimsThis study assessed the antibiotic resistance organisms isolated from the blood and bile of acute cholangitis and evaluated risk factors associated with them and their impact on clinical outcomes.MethodsThe identities and antibiotic resistance profiles of bacteria isolated from 433 cases of acute cholangitis from 346 patients were analyzed. Risk factors and the outcomes of patients infected with them were assessed.ResultsMicroorganisms were isolated from 266 of 419 blood cultures and 256 of 260 bile cultures. Isolates from bile and blood were identical in 71% of the cases. A total of 20 extended spectrum-β-lactamase (ESBL)-producers and 4 carbapenemase-producing organisms were isolated from blood, and 34 ESBL-producers and 13 carbapenemase-producers were isolated from bile. Sixty-four (14.8%) cases were infected with any one of these bacteria isolated from blood or bile. Risk factors associated with them in blood were nosocomial infection and prior biliary intervention. In bile, indwelling biliary device was a risk factor associated with them. Antibiotic-resistant bacteria were associated with mortality, independent of other prognostic factors.ConclusionsESBL or carbapenemase-producing bacteria were frequently isolated in acute cholangitis patients especially with prior biliary intervention and nosocomial infection. Isolation of antibiotic-resistant bacteria was an independent risk factor of mortality.