Resistencia bacteriana a antibióticos en ambientes acuáticos: origen e implicaciones para la salud pública

El alarmante incremento de la resistencia bacteriana a los antibióticos a nivel global ha dilucidado otras fuentes diferentes al hospital y la comunidad, donde el agua ha cobrado gran importancia. El ambiente acuático constituye la fuente y el hábitat natural de un gran número de microorganismos, incluyendo bacterias resistentes a antibióticos; así mismo, se considera uno de los principales receptores de antimicrobianos, bacterias resistentes y genes de resistencia a antibióticos provenientes de las actividades humanas. La contaminación del agua con estos contaminantes emergentes tiene implicaciones serias para la salud humana, relacionadas con la diseminación de la resistencia bacteriana y la emergencia de nuevos mecanismos de resistencia. En esta revisión se brinda una descripción global del papel de los ambientes acuáticos en el problema de la resistencia bacteriana, las principales fuentes de contaminación, además del impacto para la salud pública. Ante este panorama, se establece la necesidad de abordar la problemática de la resistencia bacteriana desde la perspectiva de "una salud", donde a la vigilancia tradicional, enfocada a nivel humano y veterinario, se articule la vigilancia epidemiológica ambiental, principalmente basada en aguas residuales.

The alarming increase in bacterial resistance to antibiotics globally has diluted sources other than the hospital and community, where water has taken on great importance. The aquatic environment is the source and natural habitat of a large number of microorganisms, including antibiotic-resistant bacteria, as well as being considered one of the main receptors for antimicrobials, resistant bacteria and antibiotic resistance genes from human activities. Contamination of water with these emerging contaminants has serious implications for human health related to the spread of bacterial resistance and the emergence of new resistance mechanisms. This review provides a global description of the role of aquatic environments in the problem of bacterial resistance, the main sources of contamination, as well as the impact on Public Health. In this context, the need arises to address the problem of bacterial resistance from the perspective of "one health", where traditional surveillance, focused at the human and veterinary level, is articulated with environmental epidemiological surveillance, mainly in wastewater.

O incremento alarmante da resistência bacteriana aos antibióticos no nível global tem revelado outras fontes diferentes do hospital e da comunidade, em que a água tem ganho grande importância. O ambiente aquático constitui a fonte e o hábitat natural de um grande número de microrganismos, incluindo bactérias resistentes a antibióticos; é considerado, também, um dos principais receptores de antimicrobianos, bactérias resistentes e genes de resistência a antibióticos provindos das atividades humanas. A poluição da água com esses poluentes emergentes tem sérias implicações para a saúde humana, relacionadas com a disseminação da resistência bacteriana e a emergência de novos mecanismos de resistência. Nesta revisão oferece-se uma descrição global do papel dos ambientes aquáticos na situação problemática da resistência bacteriana, as principais fontes de poluição, além do impacto para a saúde pública. Diante desse panorama, determina-se a necessidade de abordar a problemática da resistência bacteriana desde a perspectiva de "uma saúde" em que a vigilância tradicional, focada nos níveis humano e veterinário, esteja articulada com a vigilância epidemiológica ambiental, principalmente baseada em águas residuais.

Investigation of Factors Affecting the Success Rate of Third-Line Therapy against Helicobacter pylori Infection / 医薬品情報学

Objective: The success rate of third-line treatment for Helicobacter pylori (H. pylori) infection has been reported to depend on the use of antibacterial agents, potassium-competitive acid blockers, and proton pump inhibitors. However, there is insufficient information on the success rate of H. pylori treatment due to the differences in the clinically used drugs. Here, the factors influencing the success rate of third-line treatment for H. pylori infection was investigated.Methods: Patients aged 20 years or older, who had received third-line treatment for H. pylori infection from January 2013 to December 2021 at the Kameda Medical Center were included. The exclusion criteria were as follows: patients with unknown treatment results and discontinuation of treatment. The primary endpoint was treatment success rate, based on the differences in the treatment regimen and drug choice, which was retroactively investigated from medical records. Confounding factors were adjusted by multivariate logistic regression analysis.Results: Treatment regimens containing sitafloxacin resulted in higher treatment success rates (p<0.05). Multivariate logistic regression analysis showed that the administration of sitafloxacin was the only statistically significant factor influencing treatment success. However, vonoprazan also tended to influence treatment success.Conclusion: Treatment with sitafloxacin and vonoprazan increases the success rate of third-line treatment against H. pylori infection.

Effect of Modified Dayuansan Combined with Imipenem-cilastatin on Biofilm of Clinically Isolated Multidrug-resistant Escherichia coli / 中国实验方剂学杂志

ObjectiveTo screen out the extended spectrum beta-lactamase （ESBL）-producing Escherichia coli with the strongest biofilm-forming ability through experiments， and discuss the effect of modified Dayuansan （MDYS） combined with imipenem-cilastatin and cilastatin sodium on the biofilm of E. coli. MethodThe paper diffusion and crystal violet staining methods were used to identify 19 clinically isolated strains of drug-resistant E. coli-induced enzymes and the biofilm-forming ability. The induced enzymes and the E. coli with the strongest biofilm-forming ability were screened out. The minimum inhibitory concentration （MIC） value of MDYS and imipenem-cilastatin and cilastatin sodium was determined by 2，3-bis（2-methoxy-4-nitro-5-sulfophenyl）-2H-tetrazolium-5-carboxamide （XTT） assay. The 1/2， 1/4， and 1/8 MIC of the water extract of MDYS， imipenem-cilastatin and cilastatin sodium alone， and MDYS combined with imipenem-cilastatin and cilastatin sodium was determined by methyl thiazolyl tetrazolium （MTT） assay to obtain the optimum concentration of drugs. BioFlux dynamically observed the effect of the optimum combined drug concentration on the number of bacteria in the biofilm and the biofilm formation of E. coli， and observed the distribution of live/dead bacteria with a laser confocal scanning microscope. Finally， the morphological changes in bacteria after drug treatment were observed statically by scanning electron microscopy. ResultE5E7 strain was ESBL enzyme and the E. coli with the strongest biofilm-forming ability. The results of MTT assay showed that the MIC values of the water extracts of imipenem-cilastatin and cilastatin sodium and MDYS were 1 mg·L-1 and 250 g·L-1， respectively. The results of XTT assay showed that compared with the blank group， the 1/2， 1/4， and 1/8 MIC MDYS groups and the combined drug groups significantly decreased the number of bacteria in the biofilm （P<0.01）. The inhibitory effect diminished as the concentration of imipenem-cilastatin and cilastatin sodium decreased. Compared with the imipenem-cilastatin and cilastatin sodium group with the same concentration， the combined drug group improved the inhibitory effect on the number of bacteria in the biofilm （P<0.01）. Compared with the MDYS group with the same concentration， 1/2 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2， 1/4， and 1/8 MIC MDYS， 1/4 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2 and 1/4 MIC MDYS， and 1/8 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2 and 1/4 MIC MDYS decreased the number of bacteria （P<0.05， P<0.01）. The results of BioFlux showed that compared with the blank group， the 1/2 and 1/8 MIC imipenem-cilastatin and cilastatin sodium groups had an insignificant effect on the area of biofilm， whereas the 1/2 and 1/4 MIC MDYS groups significantly decreased the area of biofilm. The results under the scanning electron microscopy showed that as compared with the blank group and the imipenem-cilastatin and cilastatin sodium group， the division cycle was significantly longer under the action of MDYS combined with imipenem-cilastatin and cilastatin sodium. The length of the division cycle in the combined drug group was higher than that in drug alone group. ConclusionIn vitro studies reveal that MDYS combined with commonly-used antibiotics can inhibit the biofilm status of multi-drug resistant E. coli， and MDYS has the effect of enhancing sensitization and inhibiting bacteria with synergistic antibiotics.

Effect of Modified Dayuansan Combined with Imipenem-cilastatin on Biofilm of Clinically Isolated Multidrug-resistant Escherichia coli / 中国实验方剂学杂志

ObjectiveTo screen out the extended spectrum beta-lactamase （ESBL）-producing Escherichia coli with the strongest biofilm-forming ability through experiments， and discuss the effect of modified Dayuansan （MDYS） combined with imipenem-cilastatin and cilastatin sodium on the biofilm of E. coli. MethodThe paper diffusion and crystal violet staining methods were used to identify 19 clinically isolated strains of drug-resistant E. coli-induced enzymes and the biofilm-forming ability. The induced enzymes and the E. coli with the strongest biofilm-forming ability were screened out. The minimum inhibitory concentration （MIC） value of MDYS and imipenem-cilastatin and cilastatin sodium was determined by 2，3-bis（2-methoxy-4-nitro-5-sulfophenyl）-2H-tetrazolium-5-carboxamide （XTT） assay. The 1/2， 1/4， and 1/8 MIC of the water extract of MDYS， imipenem-cilastatin and cilastatin sodium alone， and MDYS combined with imipenem-cilastatin and cilastatin sodium was determined by methyl thiazolyl tetrazolium （MTT） assay to obtain the optimum concentration of drugs. BioFlux dynamically observed the effect of the optimum combined drug concentration on the number of bacteria in the biofilm and the biofilm formation of E. coli， and observed the distribution of live/dead bacteria with a laser confocal scanning microscope. Finally， the morphological changes in bacteria after drug treatment were observed statically by scanning electron microscopy. ResultE5E7 strain was ESBL enzyme and the E. coli with the strongest biofilm-forming ability. The results of MTT assay showed that the MIC values of the water extracts of imipenem-cilastatin and cilastatin sodium and MDYS were 1 mg·L-1 and 250 g·L-1， respectively. The results of XTT assay showed that compared with the blank group， the 1/2， 1/4， and 1/8 MIC MDYS groups and the combined drug groups significantly decreased the number of bacteria in the biofilm （P<0.01）. The inhibitory effect diminished as the concentration of imipenem-cilastatin and cilastatin sodium decreased. Compared with the imipenem-cilastatin and cilastatin sodium group with the same concentration， the combined drug group improved the inhibitory effect on the number of bacteria in the biofilm （P<0.01）. Compared with the MDYS group with the same concentration， 1/2 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2， 1/4， and 1/8 MIC MDYS， 1/4 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2 and 1/4 MIC MDYS， and 1/8 MIC imipenem-cilastatin and cilastatin sodium combined with 1/2 and 1/4 MIC MDYS decreased the number of bacteria （P<0.05， P<0.01）. The results of BioFlux showed that compared with the blank group， the 1/2 and 1/8 MIC imipenem-cilastatin and cilastatin sodium groups had an insignificant effect on the area of biofilm， whereas the 1/2 and 1/4 MIC MDYS groups significantly decreased the area of biofilm. The results under the scanning electron microscopy showed that as compared with the blank group and the imipenem-cilastatin and cilastatin sodium group， the division cycle was significantly longer under the action of MDYS combined with imipenem-cilastatin and cilastatin sodium. The length of the division cycle in the combined drug group was higher than that in drug alone group. ConclusionIn vitro studies reveal that MDYS combined with commonly-used antibiotics can inhibit the biofilm status of multi-drug resistant E. coli， and MDYS has the effect of enhancing sensitization and inhibiting bacteria with synergistic antibiotics.

Molecular identification of antibiotic-resistant bacteria isolated from used contact lens cases

Aims@#The contact lens (CL) has become one of the most convenience refractive devices used in vision correction, occupational and in cosmetics purposes. Despite the convenience of CL usage, poor hygiene might cause eye infections due to microbial contamination. In this work, a random collection of used CL cases among Universiti Malaysia Terengganu (UMT) students had shown the emergence of antibiotic-resistant bacteria towards commonly used antibiotics to treat eye infections.@*Methodology and results@#The study was carried out from 28 CL cases samples with the duration of one to three months of use. Bacteria that were successfully isolated from the CL cases were then exposed to the commonly prescribed antibiotics followed by identification through the partial 16S rDNA sequencing. Our finding exhibited that the rate of contamination is over 50% where 32 bacteria were isolated, with 20 (62.5%) of the isolates were Gram-positive bacteria. Approximately 31% of the isolated bacteria are resistant and intermediate resistant to the commonly used antibiotics to treat eye infection, especially erythromycin and chloramphenicol. The isolated bacteria were genotypic identified as Bacillus cereus, B. anthracis, Acinetobacter variabilis, Klebsiella pneumoniae, and Serratia marcescens. These bacteria are known as a common cause for microbial keratitis, except for A. variabilis, where the association of this bacteria in causing microbial keratitis is relatively rare.@*Conclusion, significance and impact of study@#This study highlights the emergence of antibiotic-resistant bacteria that can cause severe eye infections among CL wearer. The high percentage of contamination (>50%) found from the isolates reflected on the lack of hygiene practice on the CL handling. Thus, it is crucial to perceive this study as microbial contamination will lead to more serious eye infection disease such as conjunctivitis and keratitis.

Isolation, identification and antibiotic sensitivity pattern of Escherichia coli isolated from various clinical sample in a tertiary care hospital, Jaipur, Rajasthan, India

Background: Escherichia coli is one of the most frequent causes of many bacterial infections, including Urinary Tract Infections (UTI), blood stream infections, otitis media, pneumonia, meningitis, traveler’s diarrhoea, enteric infections and systemic infections. This study was done with the aim to surveying antibiotic sensitivity pattern of isolated Escherichia coli in both sex attended in NIMS Hospital, Jaipur under the taken time period.Methods: In this cross-sectional study, 62 Escherichia coli were isolated from various clinical specimens of the patients attending both OPD and IPD. The strains were selected using the laboratory standard methods and culture-specific. The antibiotic susceptibility testing was performed using Kirby-Bauer disk diffusion method.Results: Out of total 62 isolates of Escherichia coli 26(41.93%) isolates were from male while 36(58.064%) from female patients. Maximum sensitivity were shown by Polymyxin B and Colistin i.c 100% followed by Nitrofuratonin 82.5% followed by Meropenem 79.03%, Aztreonam 72.58%, Piperacillin/ Tazobactam and Ciprofloxacin 61.30%, each Amikacin 56.45%, Imipenem 54.83%, Ofloxacin 45.16%, Cefepime 43.54%, Ceftazidime 38.71%, Gentamycin and Ceftriaxone 37.09% each, Cefotaxime 30.64%, Norfloxacin 27.5%. Maximum resistance shown against Norfloxacin 72.5%, followed by Gentamycin and Ceftriaxone 62.90%, Ceftazidime 61.30%.Conclusions: Escherichia coli infected more in urinary tract infection as compare to other sample in human, and it is common in female than male. Regular monitoring of antimicrobial susceptibility for E.coli is recommended to improve treatment. A changing trend in antibiotic sensitivity profile of the isolates need to be monitored as there is limited availability of newer drugs and the emergence of resistant bacteria far exceeds the rate of new drug development.

Citrobacter spp. Isolated from Pus Samples in a Tertiary Care Hospital and its Antibiogram in Sonepat, Haryana, India

Introduction: Citrobacter infection occurs in a hospital setting in patients with multiple comorbidities and it occasionally causes disease in general population. Neonates and immunocompromised are highly susceptible to Citrobacter infections which are mainly caused by Citrobacter freundii and Citrobacter koseri, the incidence of nosocomial infections caused by antibioticresistant Gram-negative pathogens is increasing. This study was done to know the development of drug resistance in emerging pathogen Citrobacter. Methods: The study was conducted in the department of microbiology in a tertiary care hospital for a period of 1 year. Bacterial identification was performed by routine conventional microbial culture and biochemical tests using standard recommended techniques. The antimicrobial susceptibility testing was performed by the Kirby–Bauer disk diffusion technique on Mueller‑Hinton agar, as per the Clinical and Laboratory Standards Institute guidelines. Results: In the present study, 1788 pus samples were processed for a period of 1 year, out of which in 808 pus samples, organisms were isolated. Staphylococcus aureus was isolated in 234 (28.96%) cases. Escherichia coli was isolated in 168 (20.79%) cases, Pseudomonas was isolated in 125 (15.47%) cases, and Proteus was isolated in 32 (3.96%) cases. Enterobacter spp. was isolated in 51 (6.31%) cases. Acinetobacter was isolated in 16 (1.98%) cases. Candida spp. was 17 (2.10%). Citrobacter spp. was isolated in 85 (10.52%) cases. In 85 cases of Citrobacter spp., 58 (68.23%) were C. freundii and 27 (31.76%) were C. koseri. In the present study, Citrobacter spp. was sensitive to amikacin in 36.47% of cases, gentamycin in 48.88% of cases, and levofloxacin in 29.41% of cases. Conclusion: Citrobacter species is an emerging pathogen developing drug resistance. Drug options are limited in the current scenario; hence, injudicious and inadequate use of antibiotics should be avoided.

Prevalence of antibiotic resistant bacteria isolated from raw chicken meat

Aims@#Antibiotics are widely used in poultry industry for treatment, control and in preventing the spread of infectious diseases among chicken flocks. The uncontrolled use of antibiotic causes the emergence of antibiotic resistant bacteria which is a major concern worldwide. The aim of this study is to isolate and molecularly identify antibiotic resistant bacteria using raw chicken meat samples from farm, supermarket, wet market as well as free-range chicken. @*Methodology and results@#A total of 34 isolates were obtained through primary screening based on their ability to grow on streptomycin, kanamycin, ampicillin and cefazolin antibiotic plates. Kirby-Bauer disc diffusion test performed on the 34 isolates showed that they were highly resistant to oxacillin (97%) and penicillin (94%) followed by ampicillin (64%), cefazolin (50%), tetracycline (32%), erythromycin (24%), ciprofloxacin (21%) and least resistance towards gentamycin (6%). Eight isolates with the highest antibiotic resistance, were selected for molecular identification using 16S rDNA sequencing. Analysis of the 16S rDNA sequence using BLASTN and phylogenetic tree constructed on the selected isolates revealed that five different species of antibiotic resistant bacteria namely Escherichia coli, Klebsiella sp., Chryseobacterium gleum, Comamonas testosteroni and Bacillus cereus were successfully identified from the different types of chicken sample.@*Conclusion, significance and impact of study@#The excessive use of antibiotic in the poultry farm industries had caused the emergence of antibiotic resistant bacteria which can harm the health of people consuming chicken meat. To overcome this crisis, antibiotic usage in the poultry farm industries should be regulated.

Distribution and prevalence of antibiotic resistant bacteria in fish farms in East Malaysia

Aims@#Aquaculture has grown tremendously in Malaysia over the past decades. However, guaranteeing aquaculture sustainability is a big challenge in terms of maintaining continuous output with a safe environment. Furthermore, the cultured species should be free from antibiotic resistance bacterial and antibiotic residue. This study aimed to monitor the existence and prevalence of antibiotic resistant bacteria associated with aquaculture farms in Sarawak.@*Methodology and results@#Samples of water, sediment and fish were collected from five aquaculture farms within Sarawak. The samples were plated on trypticase soy agar and incubated at 28 °C for 24 h. A total of 204 bacterial isolates were isolated and analysed by (GTG)5-fingerprinting to determine genetic similarity among the bacterial isolates, so that representatives could be selected from similar clonal isolates. Based on the (GTG)5 profiles, 50 representative isolates were chosen for species identification using 16S rRNA sequencing. The identified bacteria were tested against 25 antibiotics using standard disk diffusion method. The 16S rRNA analysis revealed that the isolates constitute of 14 genera of bacteria including Bacillus (38%), Exiguobacterium (16%), Enterobacter (14%), Aeromonas (6%), Acinetobacter (4%), Citrobacter (4%), Staphylococcus (4%), Achromobacter (2%), Chitinophaga (2%), Fictibacillus (2%), Plesiomonas (2%), Pseudomonas (2%), Pseudoxanthomonas (2%) and Stenotrophomonas (2%). The antibiotic resistance analysis revealed that the highest percentage of resistance was recorded against streptomycin (75.0%), followed by ampicillin (66.0%), ceftriaxone (50.0%), rifampin (43.3%), aztreonam (36.8%) and ceftazidime (31.6%). Resistance to more than two antibiotics was observed in 40.0% of isolates with an overall multiple antibiotic resistant (MAR) index ranging from 0 to 0.79. @*Conclusion, significant and impact of study@#The variability of antibiotic resistance patterns exhibited by different bacterial species suggests a dependence on selective pressures exhibited in different geographical locations. Our results show that the occurrence of MAR bacteria in an aquaculture environment with unknown history of antibiotics usage in the aquaculture system is possible, indicating a need to continuously monitor the presence of antibiotic resistant bacteria in the aquaculture system.

Non Lactose Fermenter Gram Negative Bacilli Isolated From Cancer Patients

AIM AND OBJECTIVE:To know the different types of NLFs and their Antimicrobial Resistant Pattern.MATERIALS AND METHODS:This retrospective study was done from January 2012 to December 2016, in the Microbiology Laboratory of the GCRI, Ahmedabad. Different sampes like Pus discharges from post operative surgeries, absesses, flap infections, septicaemia and bacteremia, respiratory and urinary tract infections were received in the laboratory for culture and sensitivity. Standard laboratory methods were used for growth (Bactec), and automated ID AST(Vitek 2 Compact) was used for diagnosis of organism. Results: Out of 25154 samples, 48.12% (12105) bacterial growth was present including gram positive and gram negative bacteria. Out of 12105 bacterial isolation, 42.09% (5096) gram positive and 57.90% (7009) gram negative bacteria were detected. It was observed that the NLFs were quite less when compared to lactose fermenter and they accounted to 36.05% (2527/7009). Most of the NLFs, were Pseudomonas spp. 56.19% (1420) followed by next common NLF, which was Acinetobacter Spp. 34.82% (880) and others like Burkholderia spp., Stenotrophomonas spp., Achromobacter Spp. and Alcaligenes Spp. 1.22% (31) NLFs were unidentified. CONCLUSIONS:NLFs were resistant to most of the commonly used antibiotics like Beta Lactam, Beta Lactam inhibitors, Carbapenems, Aminoglycosides, Flouroquinolones. It was surprising to note that the uncommonly isolated NLF like stenotrophomonas was resistant (50-100%) to most of the antibiotics. So, the frequency of antibiotic resistant NLFs is increasing and complicating the treatment of cancer patients.

Biological characteristics and lytic effectiveness of phages isolated from domestic wastewater against indigenous Salmonella spp

Aim: This study was carried out to isolate and study the effectiveness of lytic phage from domestic wastewater to reduce the population of Salmonella spp. in patients suffering from diarrhea and to characterize biological phages. Methodology: The lytic phages from several domestic wastewater were identified using a transmission electron microscope to know morphological phages. After identifying the molecular weight protein by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, to know the effectiveness, the lytic phages were infected to Salmonella spp. from diarrheal disease patients and non-pathogenic Escherichia coli. Phage stability on thermal, pH, and buffer was then analyzed to determine the biological characteristics. Results: Three lytic phages (F-SB1, F-SB2, and F-SB3), successfully isolated from domestic wastewater, showed an icosahedral head with a short or long tail as their morphological characteristic. These phages were morphologically similar to the phages of family Siphoviridae, Myoviridae and Podoviridae. The three isolated lytic phages were stable at 27 °C to 37 °C, pH 4-7 in sodium magnesium buffer and effectively decreased the population of Salmonella spp., however could not lyse E. coli. Interpretation: All the isolated lytic phages in this study can contribute as cocktail phages in decreasing the population Salmonella spp

Molecular characterization of drug resistant Listeria monocytogenes from food and water samples

Aims@#Present research is focused on the molecular level characterization of drug-resistant Listeria monocytogenes identified from food and water samples from Tamil Nadu, India. @*Methodology and results@#A total of 39 food and water samples were collected from local markets and retail shops in Tamil Nadu, India and processed for the isolation and identification of bacteria. Morphology of the bacteria was analysed under a fluorescent microscope. Isolated bacteria were serotyped and screened for the presence of virulence-associated genes haemolysin (hlyA) and invasive associated protein (iapA) by Real-time polymerase chain reaction. The qPCR positive isolates were also typed by random amplified polymorphic DNA-PCR for epidemiological study. Antibiotic resistance test was done with 16 commercial antibiotics by disc diffusion method. A total of 8 (20.51%) L. monocytogenes were identified belonging to the serotype group 1/2a, 1/2b, 1/2c and 4b. PCR assays revealed the presence of hlyA (456 bp) and iapA (131 bp) genes. In RAPD, OPA-10 primer was found to generate the distinct polymorphic fragment among the isolates. All the isolates were 100% resistant to rifampicin, co-methoxazole, linezolid and oxacillin and 100% sensitive to tetracycline and chloramphenicol. Tetracycline and chloramphenicol are suggested to be a very effective antibiotic against the tested L. monocytogenes isolates. @*Conclusion, significance and impact of study@#The hlyA and iapA based quantitative PCR technique could be a rapid molecular technique for the detection of L. monocytogenes used in this study. Serotyping along with RAPD-PCR was able to discriminate between the isolates and therefore could serve as a robust and sensitive tool for typing antibiotic-resistant strains of L. monocytogenes.

Antimicrobial and antibiofilm activity of the essential oil from dried leaves of Eucalyptus staigeriana / Atividade antimicrobiana e antibiofilme do óleo essencial de folhas secas de Eucalyptus staigeriana

In recent years, compounds with biological properties produced by plants have received attention as an alternative to control microorganisms. Essential oils extracted from green leaves of Eucalyptus sp. have been demonstrated to have antimicrobial activities, but so far there are no reports of antimicrobial activity of essential oils extracted from dried leaves of Eucalyptus staigeriana. So, the objectives of this study were to determine the chemical composition of the essential oils obtained from dried leaves of E. staigeriana (EOdlES) and to evaluate in vitro antimicrobial and antibiofilm activities of EOdlES against gram-positive and gram-negative, resistance and multiresistant Enterococcus faecalis isolated from food and clinical samples. The characterization of EOdlES was performed by gas chromatography-mass spectrometry (GC/MS). For this study, 26 bacterial strains were used, which included 11 reference strains and 15 antibiotic resistant and multiresistant E. faecalis strains. Antimicrobial activities of EOdlES against gram-positive and gram-negative were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) value was evaluated by a microbroth dilution technique. The antibiofilm effects were assessed by microtiter plate method. As a result, 21 compounds were identified, being oxygenated monoterpenes (69.58%) the major chemical family. EOdlES showed only antimicrobial activity against gram-positive strains. E. faecalis resistant and multiresistant strains show the lowest MIC (3.12 to 6.25%), when compared with reference E. faecalis strain. EOdlES has the ability to inhibit the biofilm formation, but little or none ability to inhibit the preformed biofilm. This study demonstrates that EOdlES is a promising alternative to control important foodborne and clinic gram-positive resistant bacteria.(AU)

Nos últimos anos, compostos com propriedades biológicas produzidas por plantas têm recebido atenção como alternativa de controle de micro-organismos. Óleos essenciais extraídos de folhas verdes de Eucalyptus sp. têm demonstrado atividades antimicrobianas. No entanto, até o momento não há nenhum relato de atividade antimicrobiana de óleos essenciais extraídos de folhas secas de Eucalyptus staigeriana. O objetivo deste estudo foi determinar a composição química dos óleos essenciais obtidos de folhas secas de E. staigeriana e avaliar in vitro a sua atividade antimicrobiana e de antibiofilme contra gram-positivas e gram-negativas e também resistentes e multirresistentes de Enterococcus faecalis isolados de amostras de alimentos e clínicas. A caracterização de E. staigeriana foi realizada por CG-EM. Para este estudo foram utilizadas 26 cepas bacterianas, que incluíram 11 cepas referência e 15 cepas de E. faecalis resistentes a antibióticos. A atividade antimicrobiana de E. staigeriana contra gram-positivas e gram-negativas foi determinada utilizando o método de disco-difusão. Os valores da concentração inibitória mínima foram avaliados pela técnica de microdiluição. Os efeitos de antibiofilme foram avaliados pelo método de placa de microtitulação. Como resultado, 21 compostos foram identificados, sendo monoterpenos oxigenados (69,58%) a grande família química. E. staigeriana mostrou apenas atividade antimicrobiana contra cepas gram-positivas. Cepas de E. faecalis resistentes e multirresistentes mostraram a menor concentração inibitória mínima (3,12 para 6,25%) quando comparado com a cepa referência de E. faecalis. E. staigeriana apresentou a capacidade de inibir a formação de biofilme, mas pouca ou nenhuma capacidade de inibir o biofilme pré-formado. Este estudo demonstra que o óleo essencial obtido de folhas secas de E. staigeriana é uma alternativa promissora para controle importante de bactérias gram-positivas resistentes de origem alimentar e clínicas.(AU)

Pneumococcal vaccines

Streptococcus pneumoniae continues to take a heavy toll on childhood mortality and morbidity across the developing world. An estimated 10.6 million invasive pneumococcal diseases (IPDs) occur every year, with nearly 1 million deaths in children under 5 years of age. Introduction of vaccines in the childhood immunisation programme in developed world has brought down the incidence of the disease considerably. However, childhood immunocompromising illnesses including HIV have increased the risk of IPD several folds. There is also a growing concern on the increasing antibiotic resistance among these invasive strains to penicillin, other beta-lactams and macrolides, making treatment difficult and expensive. It is estimated that about 62% of IPD worldwide is caused by the 10 most common serotypes. Although the ranking of individual pneumococcal serotypes causing serious disease varies among nations, the 7� serotypes included in pneumococcal conjugate vaccines (PCVs) may prevent 50%�% of all paediatric pneumococcal diseases globally. The World Health Organization has recommended the use of PCV-10/13 in the national immunisation programmes (NIPs) of developing countries. Four doses of PCV-13 have been recommended by the US Association of Pediatrics and Centers for Disease Control and Prevention, at intervals of each 2 months for the first 6 months and by the 12th to 15th months after birth. This is expected to reduce the morbidity and mortality associated with IPD and simultaneously decrease colonisation with circulating antibiotic-resistant strains in immunized communities. Nevertheless, continued surveillance of antimicrobial resistance in non-vaccine serotypes is necessary to prevent the resurgence of resistance. Other virulence factors which are not serotype specific also need to be studied to overcome the drawbacks of serotype-specific pneumococcal vaccines. PCV-13 was launched during May 2017 under the NIP of five Indian states with the highest pneumococcal diseases in the country and is expected to be rolled out in the other parts of the country in the coming days.

Mechanism and influencing factors of natural transformation in bacteria / 生物工程学报

Horizontal gene transfer contributes to the spread of antibiotic-resistance cassettes, the distribution of toxin-encoding phages and the transfer of pathogenicity islands. Natural transformation, which is the process of competent cells to uptake free DNA from environment and to recombine this DNA into the chromosome, is a mode of horizontal gene transfer. Natural transformation promotes the spread of antibiotic-resistance cassettes among different bacteria, resulting in the emergence of antibiotic resistant bacteria. The emergence of antibiotic resistant pathogens poses an enormous threat to the treatment of infections. Natural transformation could occur in many bacteria, but the mechanism many be different in different bacteria. Also, the inducer and efficiency of natural transformation in different bacteria are influenced by various factors. This review focuses on the mechanism and influencing factors of natural transformation in bacteria.

Progress in strategies to combat antimicrobial resistance / 生物工程学报

Antimicrobial resistance is on the rise while the number of antibiotics being brought to market continues to drop. Drug-resistant genes and drug-resistant bacteria infection have seriously threatened human health. Therefore, antimicrobial resistance presents an ongoing challenge that requires multifaceted approaches including: biomedical innovation; improved surveillance of antibiotic consumption and antimicrobial resistance generated rates; prevention of health-care-associated infections and transmission of multidrug-resistant bacteria and environmental dissemination; rapid microbiological diagnosis; and curtailed clinical and veterinary misuse. Fortunately, combating antimicrobial resistance has been highly valued and supported by the government, scientists and entrepreneurs of various countries. With the continuous introduction of new technologies, new products, and new management measures, the problem of antimicrobial resistance must be controlled and alleviated.

Two Cases of Multi-antibiotic Resistant Cronobacter spp. Infections of Infants in China / 生物医学与环境科学（英文）

Infections by Cronobacter spp. are hazardous to infants since they can lead to neonatal meningitis, bacteremia, and necrotizing enterocolitis. Cronobacter spp. are frequently resistant to β-lactam derivatives, macrolides, and aminoglycosides. In addition, multi-resistant strains have also been detected. In China, the isolation rate of Cronobacter spp. from commercial powdered infant formula (PIF) or follow-up formula (FUF) is relatively high. Nevertheless, clinical cases of Cronobacter infection have been ignored to date. Here we describe two cases of Cronobacter infection detected at the Wuhan Women and Children Medical Care Center Hospital (Wuhan City, China). We provide the genomic analysis of the isolates and the antibiotic-resistance profiles of the two strains. The Cronobacter strains identified in this study were not susceptible to third-generation cephalosporins, aminoglycoside, and/or trimethoprim-sulfamethoxazole. Whole genome sequencing revealed various genes known to encode antibiotic resistance. Future studies are needed to determine whether the genes predicted in this study are functional. As with Enterobacter spp., the antibiotic resistance of Cronobacter is a serious issue that requires more attention.

The importance of integrons for development and propagation of resistance in Shigella: the case of Latin America

Abstract In Latin America, the disease burden of shigellosis is found to coexist with the rapid and rampant spread of resistance to commonly used antibiotics. The molecular basis of antibiotic resistance lies within genetic elements such as plasmids, transposons, integrons, genomic islands, etc., which are found in the bacterial genome. Integrons are known to acquire, exchange, and express genes within gene cassettes and it is hypothesized that they play a significant role in the transmission of multidrug resistance genes in several Gram-negative bacteria including Shigella. A few studies have described antibiotic resistance genes and integrons among multidrug resistant Shigella isolates found in Latin America. For example, in Brazil, Bolivia, Chile, Costa Rica and Peru, class 1 and class 2 integrons have been detected among multidrug resistant strains of Shigella; this phenomenon is more frequently observed in S. flexneri isolates that are resistant to trimethoprim, sulfamethoxazole, streptomycin, ampicillin, chloramphenicol, and tetracycline. The gene cassette sul2, which is frequently detected in Shigella strains resistant to the sulfonamides, suggests that the sulfonamide-resistant phenotype can be explained by the presence of the sul2 genes independent of the integron class detected. It is to be noted that sul3 was negative in all isolates analyzed in these studies.The high frequency of sulfonamide (as encoded by sul2) and trimethoprim resistance is likely to be a result of the recurrent use of trimethoprim sulfamethoxazole as a popular regimen for the treatment of shigellosis. The observed resistance profiles of Shigella strains confirm that ampicillin and trimethoprim-sulfamethoxazole are ineffective as therapeutic options. In-depth information regarding antibiotic resistance mechanism in this pathogen is needed in order to develop suitable intervention strategies. There is a pressing need for regional and local antimicrobial resistance profiling of Shigella to be included as a part of the public health strategy.

Genomic profile of antibiotic resistant, classical ctxB positive Vibrio cholerae O1 biotype El Tor isolated in 2003 and 2005 from Puri, India: A retrospective study.

Objectives: To examine eight strains of Vibrio cholerae O1 isolated in 2003 and 2005 from Puri, India, for antibiotic susceptibility, presence of virulence and regulatory genes, cholera toxin (CT) production, CTX arrangement and genomic profiles. Materials and Methods: Bacterial strains were tested for antibiotic susceptibility using disc diffusion assay. Polymerase chain reaction determined the presence of antibiotic resistance, virulence and regulatory genes. To determine the type of cholera toxin subunit B (ctxB), nucleotide sequencing was performed. Southern hybridisation determined the number and arrangement of CTXΦ. Ribotyping and pulsed‑field gel electrophoresis (PFGE) were used to determine the genomic profile of isolates. Results: All the eight strains, except one strain, showed resistant to nalidixic acid, sulphamethoxazole, streptomycin and trimethoprim and possessed the sullI, strB, dfrA1 and intSXT genes. All the strains carried the toxin‑co‑regulated pilus pathogenicity island, the CTX genetic element, the repeat in toxin and produced CT. Restriction fragment length polymorphism (RFLP) analysis showed that V. cholerae O1 possess a single copy of the CTX element flanked by tandemly arranged RS element. Nucleotide sequencing of the ctxB gene showed the presence of classical ctxB. RFLP analysis of conserved rRNA gene showed two ribotype patterns. PFGE analysis also showed at least three PFGE patterns, irrespective of year of isolations, indicating the genomic relatedness among them. Conclusion: Overall, these data suggest that classical ctxB‑positive V. cholerae O1 El Tor strains that appeared in 2003 continue to cause infection in 2005 in Puri, India, and belong to identical ribotype(s) and/or pulsotype(s). There is need to continuous monitor the emergence of variant of El Tor because it will improve our understanding of the evolution of new clones of variant of V. cholerae.

Multi-Drug Resistance of Bacterial Isolates among Dental Caries Patients

Background and Objectives: Dental caries is a well known major oral health problem in most developing countries which has multifactorial etiology caused by many facultatively anaerobes. S. mutans is the main pathogen associated with this disease. Recently Multi-Drug Resistant (MDR) species of S. mutans were identified from the dental caries patients against many commercial antibiotics. MDR is a natural phenomenon, posing a serious worldwide threat to public health. Several therapeutic agents are available to treat or prevent tooth decay, but still global burden of the disease with MDR are emerging. Therefore, the present study was designed for assessing the antibiotic sensitivity pattern of commercially available antibiotics.Material and Methods: This cross-sectional study was carried out by following Standard protocols of Bergey’s Manual of Systematic Bacteriology to isolate and identify the organism and further followed by antibiotic susceptibility test of bacterial isolates by disc diffusion method.Results: Streptococcus mutans (40%) was the most predominant to cause dental caries followed by S. aureus with 28.92. Gram positive isolates were found to be frequently resistant towards penicillin and tetracycline whereas Gram negative isolates were found to be Cotrimoxazole resistant.Conclusion: A high frequency of penicillin resistance in oral isolates and its co-resistance to erythromycin, tetracycline, gentamycin and amipicillin among the pateints was observed. The various awareness programmes should be facilitating the appropriate use of antibiotic to re-establish dominance over diseases must be implemented.