Presence Of Antibiotic-resistant Bacteria Research Articles

Fibrous testing papers for fluorescence trace sensing and photodynamic destruction of antibiotic-resistant bacteria.

The increasing prevalence of antibiotic-resistant bacteria needs rapid identification and efficient destruction routes. This study proposes testing paper derived from electrospun fibrous mats and aggregation-induced emission (AIE) probes for trace sensing and simultaneous destruction of antibiotic-resistant E. coli. Aptamers are conjugated on fibers for selective capture of E. coli, and the capture capability can be regenerated via rinsing with salt solution. Hydroxyl tetraphenylethene (TPE) is linked with two cephalosporin molecules to construct TPE-Cep probes, and the fluorescence emission is turned on specifically in the presence of β-lactamase, which is a critical marker for screening resistant bacteria. Fibrous mats are lit up only in the presence of antibiotic-resistant bacteria, and the fluorescence intensity changes could be statistically fitted into an equation for quantitative analysis. Fibrous strips display apparent color changes from blue to green for a visual readout of bacterial levels, and the limit of detection (LOD) is much lower than those of previous paper substrates. In addition, the TPE-Cep probes could produce reactive oxygen species (ROS) under room light illumination to kill the captured bacteria. Thus, the integration of aptamer-grafted electrospun fibers and functional AIE probes provides potential for selective capture, trace imaging and photodynamic destruction of antibiotic-resistant bacteria.

Occurrence and distribution of tetracycline resistance determinants and their pollution profile in the aquaculture environment in Sri Lanka

Tetracyclines (TET) have been extensively used in aquaculture for chemotherapy against various fish diseases. The occurrence of tetracycline contamination levels in the aquaculture farms in Sri Lanka were analyzed using High Performance Liquid Chromatography (HPLC). The presence of antibiotic-resistant bacteria was identified using the 16SrRNA gene sequencing and the corresponding antibiotic resistance genes (ARGs) were screened at each location using PCR method. The concentration of TET in aquaculture farms ranged between 0.001± 0.001 - 0.112± 0.017 ppm whereas Bacillus and Staphylococcus were the most dominant bacterial genera as TET resistant bacteria. Acinetobacter sp., Achromabacter sp., Staphylococcus sp., Micrococcus sp. were also identified as the resistant bacteria. In the present study, tet (M) and tet (A) were abundant resistance genes (11/16 isolates), followed by tet (S) (5/16) and tet (B) (4/16). It was found that tet (M) is one of the most widely distributed tetracycline resistance determinant in the aquatic environment in Sri Lanka.

Removal of microorganisms and antibiotic resistance genes from treated urban wastewater: A comparison between aluminium sulphate and tannin coagulants

The presence of antibiotic resistant-bacteria (ARB) and antibiotic resistance genes (ARG) in treated effluents of urban wastewater treatment plants (WWTP) may represent a threat to the environment and public health. Therefore, cost-effective technologies contributing to minimize loads of these contaminants in the final effluents of WWTP are required.This study aimed at assessing the capacity of coagulation to reduce the ARB&ARG load in secondary treated urban wastewater (STWW), as well as the impact of the process on the structure and diversity of the bacterial community. Coagulation performance using aluminium sulphate, a synthetic substance, and tannins, a biowaste, was compared. Samples were analysed immediately before (STWW) and after the coagulation treatment (Alu, Tan), as well as after 3-days storage in the dark at room temperature (RSTWW, RAlu, RTan), to assess possible reactivation events.Both coagulants decreased the turbidity and colour and reduced the bacterial load (16S rRNA gene copy number, total heterotrophs (HET), and ARB (faecal coliforms resistant to amoxicillin (FC/AMX) or ciprofloxacin (FC/CIP) up to 1–2 log immediately after the treatment. Both coagulants reduced the load of intl1, but in average, aluminium sulphate was able to decrease the content of the analysed ARGs (blaTEM and qnrS) to lower levels than tannin. Reactivation after storage was observed mainly in RTan. In these samples the load of the culturable populations and qnrS gene prevalence increased, sometimes to values higher than those found in the initial wastewater.Reactivation was also characterized by an increment in Gammaproteobacteria relative abundance in the bacterial community, although with distinct patterns for RTan and RAlu. Curvibacter, Undibacterium and Aquaspirillum were among the most abundant genera in RAlu and Aeromonas, Pseudomonas and Stenotrophomonas in RTan. These bacterial community shifts were in agreement with the variations in the culturable bacterial counts of HET for RTan and FC/CIP for RAlu.In summary, the overall performance of aluminium sulphate was better than that of tannins in the treatment of treated urban wastewater.

Identification and antibiotic susceptibility of bacterial microbiota of freshwater fish

The fish meat is an essential part of human diet. However, fish may be contaminated with different microorganisms, including pathogens. Antimicrobial resistance of fish microbiota may facilitate the spread of resistant microorganisms causing serious consequences for human health. The aim of the present study was to detect bacterial contamination in fish gill, gut and skin and to determine antimicrobial susceptibility of the bacterial isolates. Rainbow trout (Oncorhynchus mykiss) and bream (Abramis bram) were obtained from the market in Jelgava city. Chub (Leuciscus cephalus), crucian carp (Carassius carassius) and tench (Tinca tinca) were collected from fishermen. Fish samples were examined for the total bacterial count (TBC), coliforms, Enterobacteriaceae, Pseudomonas spp. and Aeromonas spp. Testing was done in accordance with International Organization for Standardization (ISO) standards. Identification of all bacteria was accomplished with the Matrix Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry (MALDI-TOF MS) method. The disc diffusion method was used for the detection of antibiotic susceptibility of isolated bacterial species. TBC ranged from 2.70 to 7.00 log CFU.g-1, coliforms from 0 to 2.67 log CFU.g-1, Enterobacteriaceae from 0 to 2.85 log CFU.g-1. The highest contamination with Pseudomonas spp. and Aeromonas spp. was observed in chub gut samples with 1.60 log CFU.g-1 and 2.23 log CFU.g-1, respectively. Altogether, 16 microbial genera and 31 bacterial species were identified. The dominant bacterial species belonged to Pseudomonas spp. (54%) and Enterobacteriaceae. Pseudomonas spp. were resistant to ticarcillin, susceptibility to ciprofloxacin showed 88% of isolates. All Enterobacteriaceae isolates were susceptible to imipenem. The microbial quality of the fish was acceptable, but the presence of antibiotic resistant bacteria may further cause a negative impact on public health.

Presence, dissemination and removal of antibiotic resistant bacteria and antibiotic resistance genes in urban drinking water system: A review

Antibiotic resistance in aquatic environment has become an important pollution problem worldwide. In recent years, much attention was paid to antibiotic resistance in urban drinking water systems due to its close relationship with the biosafety of drinking water. This review was focused on the mechanisms of antibiotic resistance, as well as the presence, dissemination and removal of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the urban drinking water system. First, the presence of ARB and ARGs in the drinking water source was discussed. The variation of concentration of ARGs and ARB during coagulation, sedimentation and filtration process were provided subsequently, in which filtration was proved to be a promising technology to remove ARGs. However, biological activated carbon (BAC) process and drinking water distribution systems (DWDSs) could be incubators which promote the antibiotic resistance, due to the enrichment of ARGs and ARB in the biofilms attached to the active carbon and pipe wall. Besides, as for disinfection process, mechanisms of the inactivation of ARB and the promotion of conjugative transfer of ARGs under chlorine, ozone and UV disinfection were described in detail. Here we provide some theoretical support for future researches which aim at antibiotic resistance controlling in drinking water.

Occurrence of antibiotic resistance among Gram negative bacteria isolated from effluents of fish processing plants in and around Mangalore

ABSTRACT The presence of antibiotic-resistant bacteria in seafood not only poses a serious health risk for the consumers but also contributes to the spread of these antibiotic-resistant bacteria in the natural environments through the effluents discharged from the fish processing plants. The aims of this study were to isolate Gram-negative bacteria from the effluents of fish processing plants in and around Mangalore, India and to profile their antibiotic resistance pattern. Maximum resistance was seen for ampicillin (40.78%) followed by tetracycline (40.22%) and nitrofurantoin (29.05%). Further, the detection of genes that contribute to antibiotic resistance revealed the presence of sulfonamide resistance genes (sul1 and sul2) and extended spectrum β-lactamase genes (bla CTX-M, bla TEM) in a few isolates. The presence of such bacteria in fish processing effluents is a matter of great concern because they can contribute significantly to the antibiotic resistance in the natural environment. It is imperative that seafood processing plants follow the safe disposal of effluents in order to reduce or eliminate the antibiotic resistance menace.

Kinetic assessment of antibiotic resistant bacteria inactivation by solar photo-Fenton in batch and continuous flow mode for wastewater reuse

The presence of antibiotic resistant bacteria in municipal wastewater treatment plants represents a real risk to human health. For the first time, this paper shows that the inactivation rate of cefotaxime resistant bacteria is the same as total bacteria when secondary effluents are treated by the solar photo-Fenton process. To obtain this result, an exhaustive and comparative kinetic study on the inactivation of both total and cefotaxime resistant bacteria (Total coliform, Escherichia coli and Enterococcus sp) was carried out, taking into account the effects of the main operation conditions, such as solar irradiance and iron concentration, and operation mode (batch and continuous). In all the operation conditions studied, no significant differences were found between the first order inactivation rate constants, ki, of total and cefotaxime resistant bacteria. Additionally, ki increased with solar irradiance and iron concentration. As for the effect of the operation mode, the main finding of this work is much quicker inactivation in continuous flow mode than in batch mode, pointing out its potential application at large scale. The best continuous operation condition to inactivate the bacteria to the detection limit (1 CFU mL−1), was at 22.4 min of hydraulic residence time with 5 mg Fe2+ L−1 and 30 mg H2O2·L−1. This treatment time is approximately a third of that reported in batch mode. The efficiency, in terms of figure of merits, of the continuous flow operation was 2.7 m2 of solar collector area to reduce one log of E. coli concentration per m3 of treated water and per hour, in comparison with 2137 m2 calculated for batch operation under the same solar UVA irradiance, 30 W m−2. This paper encourages research into continuous solar disinfection processes due to its enhanced efficiency with regard to the commonly used batch wise operation and shows that efficient removal of total bacteria ensures the removal of antibiotic resistant bacteria.

Water pollution and observation of acquired antibiotic resistance in Bayou Lafourche, a major drinking water source in Southeast Louisiana, USA

Antibiotics are known to enter the environment, not only by human excretion but also through livestock/aquaculture, healthcare facilities, and pharmaceutical industry waste. Once in the environment, antibiotics have the ability to provide a selective pressure in microbial communities thus selecting for resistance. Bayou Lafourche of Southeastern Louisiana serves as the raw source of drinking water for 300,000 people in the region and has previously been shown to receive high amounts of fecal contamination. Four sites along the bayou and one site from its input source on the Mississippi River were monitored for water chemistry, total and fecal coliform estimates, and presence of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARG) for a period of 1year. Four waste-associated bacterial isolates were tested for resistance to antibiotics (tetracycline, sulfamethoxazole/trimethoprim, cefoxitin, meropenem, imipenem, erythromycin, and vancomycin). Resistant bacteria were further examined with PCR/electrophoresis to confirm the presence of antibiotic resistance genes (Sul1, tet(A), tet(W), tet(X), IMP, KPC, and OXA-48). The bayou appears to meet the Louisiana Department of Environmental Quality (LDEQ) criteria for water chemistry, yet fecal coliforms were consistently higher than LDEQ thresholds, thus indicating fecal contamination. Enterobacteriaceae isolates showed 13.6%, 10.9%, and 19.8% resistant to tetracycline, sulfamethoxazole/trimethoprim, and cefoxitin, respectively, and 11 isolates were confirmed for presence of either tet(A) or Sul1 resistance genes. High fecal coliforms and presence of ARB/ARG may both indicate a presence of anthropogenic or agricultural source of fecal contamination.

Beta laktamaze proširenog spektra delovanja kod reda Enterobacterales - klasifikacija i genetska osnova rezistencije

Beta-lactam antibiotics are one of the most important ones in clinical practice and most commonly prescribed drugs. There are few possible mechanisms of beta-lactam resistance. Beta-lactamase opens the b-lactam ring, deactivating the molecule's antibacterial properties, and among them, Extended-spectrum beta-lactamases (ESBL) are the most important. Antibiotic resistance gene can both be located on chromosome, or on plasmids. Betalactamases share the ability to hydrolyse penicillin, cephalosporin and monobactam, but not carbapenems and cephamycin, and yet, they are inhibited by clavulanic acid and/or tazobactam. Far most important in clinical practice are CTX-M enzymes, followed by TEM and SHV. Other less widespread ones are VEB, PER, GES, TLE, IBC, BES, BEL and others. Over the last years the presence of antibiotic resistant bacteria has been shown outside the clinical environment, including water, soil and food producing animals. If this problem persists in all over the world, carbapenems might be the first line antibiotics. Considering the present situation, antimicrobial resistance could be one of the greatest challenges in modern medicine, and it is important to ensure that antibiotics are prescribed only when needed.

Microbial Assessment of Tomatoes (Lycopersicon esculentum) Sold at Some Central Markets in Ghana.

Background Tomato (Lycopersicon esculentum) has a high water content which predisposes it to spoilage by pathogenic bacteria that can pose significant health threats to consumers. Aim The study aimed to determine the various pathogenic bacteria associated with tomatoes sold in some central markets in the Accra Metropolis. Method A total of 120 tomatoes were sampled, out of which 60 fresh, firm, undamaged tomatoes and 60 spoilt tomatoes were analysed. Cut portions of the fresh and spoilt tomatoes were swabbed with sterile swabs and cultured on Blood agar, Nutrient agar, and MacConkey agar. The antibiogram of bacterial isolates was determined by Kirby-Bauer disc-diffusion method. Results Out of the 120 tomatoes analysed, a total of 66 bacterial isolates were recovered, 68.2% were associated with spoilt tomatoes, and 31.8% were from fresh tomatoes. Klebsiella sp. (34.8%), Enterobacter sp. (24.2%), and Citrobacter sp. (7.6%) were the predominant bacteria isolated. Agbogbloshie market (36.4%) had both fresh (18.2%) and spoilt (18.2%) tomatoes contaminated, whilst Makola market (31.8%) had a higher spoilt (30.3%) tomatoes contaminated. Although none of the isolates expressed resistance to ciprofloxacin, resistance was found for ampicillin (63.1%), tetracycline (60.1%), and cefuroxime (59.1%). Conclusion Varying levels of antibiotic resistance bacteria amongst tomatoes sold at various markets were found. Contamination might have been caused by poor sanitation, improper handling or transportation from the farms to the markets. The presence of antibiotic resistance bacteria amongst tomatoes raises concern on public health risks associated with the consumption of fresh tomatoes.

Potential of Spray Dried Animal Plasma as an Alternative In-Feed Growth Promoter in Poultry Production

The presence of antibiotic-resistant bacteria in the gastrointestinal tracts of poultry and livestock have continued to increase governmental and consumer pressure on the food animal industry to halt the use of antimicrobials in animal feed. Research efforts in this regard have continued to focus on identifying alternative biogenics and nutraceuticals.

Antibiotic-Resistant Bacteria in Greywater and Greywater-Irrigated Soils.

This study represents the first systematic attempt to evaluate antibiotic-resistant bacteria (ARB) occurrence in treated greywater and the potential spread of these bacteria from the greywater to greywater-irrigated soil. Treated greywater from three recirculating vertical flow constructed wetlands, each located in a household in the central Negev Desert, Israel, was surveyed. The presence of antibiotic-resistant bacteria in raw and treated greywater was investigated with culture and molecular methods, as well as their presence in the corresponding treated-greywater-irrigated soils. Additionally, the effectiveness of chlorination to prevent the spread of ARB was tested. The total count of tetracycline-resistant bacteria significantly increased in the treated greywater, likely due to their concentration on the filter matrix of the treatment systems. Twenty-four strains of tetracycline-resistant bacteria were isolated and identified at the genus level by 16Sr RNA gene sequencing. All the tetracycline-resistant bacteria showed high resistance traits, and some of them presented multiple antibiotic resistances. Six tetracycline resistance genes (coding for efflux and ribosomal resistance mechanisms) and five β-lactamase genes were detected. In 14 of the isolated strains, the gene tet39, which is phylogenetically related to both environmental and clinical strains, was identified. All the tet39 resistant bacteria were positive to at least one of the β-lactamase genes tested. Chlorination was found to be an efficient method to reduce ARB in treated greywater. We concluded that disinfection of treated greywater may reduce the risks not only from the potential presence of pathogens but also from the presence of ARB and antibiotic resistance genes.

Unraveling the Role of Vegetables in Spreading Antimicrobial-Resistant Bacteria: A Need for Quantitative Risk Assessment.

In recent years, vegetables gain consumer attraction due to their reputation of being healthy in combination with low energy density. However, since fresh produce is often eaten raw, it may also be a source for foodborne illness. The presence of antibiotic-resistant bacteria might pose a particular risk to the consumer. Therefore, this review aims to present the current state of knowledge concerning the exposure of humans to antibiotic-resistant bacteria via food of plant origin for quantitative risk assessment purposes. The review provides a critical overview of available information on hazard identification and characterization, exposure assessment, and risk prevention with special respect to potential sources of contamination and infection chains. Several comprehensive studies are accessible regarding major antimicrobial-resistant foodborne pathogens (e.g., Salmonella spp., Listeria spp., Bacillus cereus, Campylobacter spp., Escherichia coli) and other bacteria (e.g., further Enterobacteriaceae, Pseudomonas spp., Gram-positive cocci). These studies revealed vegetables to be a potential—although rare—vector for extended-spectrum beta-lactamase-producing Enterobacteriaceae, mcr1-positive E. coli, colistin- and carbapenem-resistant Pseudomonas aeruginosa, linezolid-resistant enterococci and staphylococci, and vancomycin-resistant enterococci. Even if this provides first clues for assessing the risk related to vegetable-borne antimicrobial-resistant bacteria, the literature research reveals important knowledge gaps affecting almost every part of risk assessment and management. Especially, the need for (comparable) quantitative data as well as data on possible contamination sources other than irrigation water, organic fertilizer, and soil becomes obvious. Most crucially, dose–response studies would be needed to convert a theoretical “risk” (e.g., related to antimicrobial-resistant commensals and opportunistic pathogens) into a quantitative risk estimate.

Presence of antibiotic-resistant bacteria and antibiotic resistance genes in coastal recreational waters of southeast Louisiana, USA

Presence of antibiotic-resistant bacteria and antibiotic resistance genes in coastal recreational waters of southeast Louisiana, USA

Bacterial Remediation of Ciprofloxacin (CIP) by CIP Resistance Bacteria Isolated from Environment Samples

Ciprofloxacin (CIP) is a fluoroquinolone antibacterial drug widely used in treatment of pathogenic infectious diseases in human. A significant quantity of CIP is metabolised incompletely by patients after administration and enter to the environment with patients’ excretion. Therefore, studies on the biodegradability of drugs can be taken as a very first step of an environmental risk assessment. The present study reports the biodegradation of CIP by Lactobacillus gesseri, Enterobacter sp., Bacillus sp., Bacillus subtilius and Micrococcus luteus which were isolated as CIP resistance, non-pathogenic bacteria. The presence of antibiotic-resistant bacteria was identified using the 16s rRNA sequencing. A 0.5 ml of overnight starved bacterial suspension was introduced into medium containing CIP at final concentration of 5 ppm. Triplicate samples were incubated at 2800 C with shaking at 100 ppm. A 0.5 ml of subsample was removed at 2 days interval for a period of 14 days. Samples were subjected to High Performance Liquid Chromatography (HPLC) analysis. Fourier Transform Infrared Spectroscopy (FTIR) analyses were carried out for each sample at the end of the 14 days to find structures of by-products. Complete degradation of CIP by L. gesseri was detected at the end of 14 days of incubation with average degradation rate of 0.182±0.15 d-1. Descending degradation rates were followed by Enterobacter sp. (0.75±0.03 d-1) and Bacillus sp. (0.41±0.02d-1) at 8 and 6 days respectively. However, clear cut degradation of CIP was not detected for B. subtilis and M. luteus respectively. Further, FTIR spectrum revealed that incubation of L. gesseri, Enterobacter sp. and Bacillus sp., breakdown the piperazine ring and quinolone part in the CIP structure while degradation occurred. Keywords: Ciprofloxacin; Degradation, Fourier Transform Infrared Spectroscopy (FTIR), High Performance Liquid Chromatography (HPLC); Lactobacillus gesseri

Prevalence of antibiotics and antibiotic resistance genes in a wastewater effluent-receiving river in the Netherlands

Antibiotics are being used intensively for humans and livestock worldwide and have led to the presence of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment. Wastewater treatment plants (WWTPs) have been identified as a point source for ARB&Gs, and water catchments consequently are potential receptors of ARB&Gs. The objective of this study was to investigate the occurrence of antibiotics (macrolides, sulfonamides, tetracyclines), ARGs (ermB, sul1, sul2, tetW), and class 1 integron (targeting the integrase gene), in a Dutch river that receives wastewater treatment plant effluent. Sediment and water samples were collected during one year along the river. The WWTP significantly increased the amounts of antibiotics and ARGs in the river as compared to the upstream samples, of which the antibiotics decreased once they entered the river. ARGs were persistent in the water and sediment from the WWTP effluent discharge point until 20 km downstream. This study provides insight in the prevalence of antibiotics and ARGs in a wastewater effluent-receiving river system in the Netherlands. Even though human antibiotic usage is low in the Netherlands, antibiotics, residues of antibiotics, and ARGs are detected in the river surface water-sediment system, which shows that a river has the potential to act as a reservoir of ARGs.

Antibiotic Resistant Bacteria in Municipal Wastes: Is There Reason for Concern?

Recently, there has been increased concern about the presence of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG), in treated domestic wastewaters, animal manures and municipal biosolids. The concern is whether these additional sources of ARB contribute to antibiotic resistance levels in the environment, that is, "environmental antibiotic resistance." ARB and ARG occur naturally in soil and water, and it remains unclear whether the introduction of ARB in liquid and solid municipal and animal wastes via land application have any significant impact on the background levels of antibiotic resistance in the environment, and whether they affect human exposure to ARB. In this current review, we examine and re-evaluate the incidence of ARB and ARG resulting from land application activities, and offer a new perspective on the threat of antibiotic resistance to public health via exposure from nonclinical environmental sources. Based on inputs of ARBs and ARGs from land application, their fate in soil due to soil microbial ecology principles, and background indigenous levels of ARBs and ARGs already present in soil, we conclude that while antibiotic resistance levels in soil are increased temporally by land application of wastes, their persistence is not guaranteed and is in fact variable, and often contradictory based on application site. Furthermore, the application of wastes may not produce the most direct impact of ARGs and ARB on public health. Further investigation is still warranted in agriculture and public health, including continued scrutiny of antibiotic use in both sectors.

Identification of Antibiotic Resistant Gram-Negative Bacteria in a Popular Street-Food Item (Chatpati) in Dhaka University Campus, Bangladesh

Presence of antibiotic resistant bacteria in street-foods has become a global health concern. In this study, we have thoroughly investigated the bacteriological quality of Chatpati (CHT) samples collected from 7 different locations of Dhaka University campus. Various selective and differential media, Gram staining and biochemical tests were carried out for isolation, enumeration and characterization of the isolates. The total bacterial count varied in samples from 7 locations ranging from 1.1x10³ to 4.1x106 CFU/g. Klebsiella spp., Escherichia coli (E. coli), Enterobacter spp., Vibrio spp., Proteus spp., Pseudomonas aeruginosa and Aeromonas spp. were identified in the collected CHT samples. Isolates were then subjected to antibiotic susceptibility test. For antibiogram profiling, Ampicillin, Colistin, Chloramphenicol, Ceftriaxone, Ciprofloxacin and Nitrofurantoin were employed in this study. Multiple antibiotic resistance index (MRI%) of the isolates were found to be ranged from 16.67 to 66.67%. Majority of the isolates showed resistance against Ampicillin and Nitrofurantoin. Therefore, it may be concluded that the consumption of CHT from this area may be severely detrimental to health due to the presence of antibiotic resistant bacteria.

Isolation of Antibiotic-Resistant Micrococcus aloeverae from Milk Powder

The emergence of antibiotic resistance in humans via the food chain has become an area of great concern. Antibiotic resistance gene transfer from a food-borne bacteria or probiotic agent to a human gut microbe can lead to a serious food safety issue. Such seemingly harmless bacteria or probiotics can potentially become a threat to human health if they carry mobile genes conferring antibiotic resistance. The recent trend of probiotic application in powdered infant formula and milk products and the presently known contamination of these products by certain opportunistic Enterobacteriaceae bacteria serves as the rationale for evaluating their safety. In this study, 25 milk powder samples and 25 powdered infant formula samples were analyzed for the presence of antibiotic resistant bacteria of family Enterobacteriaceae using an isolation technique. Out of the 50 samples screened, an isolate was detected in one milk powder sample. Its biochemical characteristics, Gram character, antibiotic susceptibility, and motility were analyzed. It was found to be a Gram-positive, non-motile, catalase-positive and oxidase-negative microbe. The isolate was resistant to Rifampicin and Vancomycin, but susceptible towards Streptomycin, Ciprofloxacin, Ceftriaxone and Gentamycin. Molecular characterization by 16S rDNA sequencing identified the isolate as Micrococcus aloeverae. The unique occurrence of Micrococcus aloeverae in milk powder elicits an area of food safety concern for such samples. To the best of our knowledge, this study is the first to report antibiotic resistance by Micrococcus aloeverae. Although it may be a non-pathogenic microbe, its resistance towards antibiotics cannot be ignored. The possibility of Micrococcus aloeverae serving as a potential vehicle for transfer of antibiotic resistance genes to human gut microbiota represents a prospective food safety concern.

Restricting the use of antibiotics in food-producing animals and its associations with antibiotic resistance in food-producing animals and human beings: a systematic review and meta-analysis

SummaryBackgroundAntibiotic use in human medicine, veterinary medicine, and agriculture has been linked to the rise of antibiotic resistance globally. We did a systematic review and meta-analysis to summarise the effect that interventions to reduce antibiotic use in food-producing animals have on the presence of antibiotic-resistant bacteria in animals and in humans.MethodsOn July 14, 2016, we searched electronic databases (Agricola, AGRIS, BIOSIS Previews, CAB s, MEDLINE, Embase, Global Index Medicus, ProQuest Dissertations, Science Citation Index) and the grey literature. The search was updated on Jan 27, 2017. Inclusion criteria were original studies that reported on interventions to reduce antibiotic use in food-producing animals and compared presence of antibiotic-resistant bacteria between intervention and comparator groups in animals or in human beings. We extracted data from included studies and did meta-analyses using random effects models. The main outcome assessed was the risk difference in the proportion of antibiotic-resistant bacteria.FindingsA total of 181 studies met inclusion criteria. Of these, 179 (99%) described antibiotic resistance outcomes in animals, and 81 (45%) of these studies were included in the meta-analysis. 21 studies described antibiotic resistance outcomes in humans, and 13 (62%) of these studies were included in the meta-analysis. The pooled absolute risk reduction of the prevalence of antibiotic resistance in animals with interventions that restricted antibiotic use commonly ranged between 10 and 15% (total range 0–39), depending on the antibiotic class, sample type, and bacteria under assessment. Similarly, in the human studies, the pooled prevalence of antibiotic resistance reported was 24% lower in the intervention groups compared with control groups, with a stronger association seen for humans with direct contact with food-producing animals.InterpretationInterventions that restrict antibiotic use in food-producing animals are associated with a reduction in the presence of antibiotic-resistant bacteria in these animals. A smaller body of evidence suggests a similar association in the studied human populations, particularly those with direct exposure to food-producing animals. The implications for the general human population are less clear, given the low number of studies. The overall findings have directly informed the development of WHO guidelines on the use of antibiotics in food-producing animals.FundingWorld Health Organization.