Threefold Increase in the Number of Drug Resistant TB Cases after Introduction of Universal Drug Susceptibility Testing: Experiences from Two South India Districts

Background: In India, tuberculosis (TB) is a major public health problem, and the advent of drug resistance TB (DR-TB) has worsened the situation. The Revised National TB Control Programme (RNTCP) has introduced universal drug susceptibility testing (UDST) for all diagnosed TB cases in 2018. We conducted this study to know the advantage of implementing UDST when compared to selective testing existent in 2017 on key diagnostic cascade parameters and to identify the challenges in the implementation of UDST. Methods: The study was conducted in two districts of Karnataka, India during January 2017-December 2018. The quantitative part consisted of before-and-after design and the qualitative part consisted of descriptive design. Results: In 2017 (during selective testing/“before” period) out of the 2440 TB patients, 80 (3%) were diagnosed with Isoniazid and Rifampicin resistance patients;in contrast in 2018 (during UDST/“after” period) of the 5129 TB patients 258 (5%) were diagnosed with Isoniazid and Rifampicin resistance. However, the proportion of eligible patients tested for rifampicin resistance during the “after” period was 60% when compared to 100% during the “before” period and median turnaround time for testing was also longer during the “after” period when compared to the “before” period (32.5 days vs 27.5 days). Major reasons for these two gaps were found to be difficulties in collecting sputum specimens and transportation. Conclusion: The rollout of UDST has led to a three-fold increase in a number of DR-TB cases detected in the region. There is a need for the programme to increase the proportion tested for DST by increasing the laboratory capacity and address the challenges in sputum collection and transportation.

Drug Susceptibility Test of Volatile Oil of Artemisiaargyi to Avian Pathogenic Escherichia coli

The volatile oil of Artemisia argyi was extracted by ultrasonic assisted extraction, and the extraction rate of volatile oil was 0.68%. Thevolatile oil of A. argyi was emulsified with 1% Tween-80, and drug susceptibility test was conducted with avian Escherichia coli. The results showedthat the volatile oil of A. argyi had antibacterial effect against avian E. coli, and the minimal inhibitory concentration was 50 mg/mL. Taking sixcommon antibiotics as the control, drug susceptibility test was conducted with volatile oil of A. argyi. The results showed that 10 strains of E. coliwere sensitive to the volatile oil of A. argyi, three of which had different degrees of resistance and one had the tendency of resistance.

Comparative drug susceptibility study of five clonal strains of Trichomonas vaginalis in vitro

Objective:To produce comparative data on a group of Trichomonas vaginalis clonal strains with varied drug responses using identical methods and materials.Methods:Five clonal strains of Trichomonas vaginalis were isolated from reference strain using agar plate technique.The variability of growth kinetic and susceptibility of clonal strain to metronidazole,tinidazole, satranidazole and nitazoxanide were observed in 96 well microlilre plate.Results:Among these clonal strains there was a good correlation between rates of growth with the relative susceptibility of the strains to drugs in vitro.Regarding metronidazole,tinidazole and satranidazole susceptibility,different degrees of susceptibility were determined.However,no difference in nitazoxanide susceptibility was found between the clonal strain tested and a reference strain. Conclusions:This is the first description of biological variability in clonal stock of Trichomonas vaginalis.Different degrees of drug susceptibility were determined among clonal strains tested. Further studies will be necessary to ascertain the importance of this variability in clinical infection.

Isolation and Identification of Four Strains of Salmonella and Drug Susceptibility Test

In order to isolate and identify the pathogenic bacteria causing dead chickens in a chicken farm in Qinhuangdao area, the liver, heart and other organs of dead chickens suspected of salmonella disease were collected aseptically, and streaked on SS agar medium and chromagar medium. Transparent colonies were observed on SS agar medium, and purple and transparent colonies on CAS medium. The isolate was conducted purification, staining microscopy, biochemical tests, and 16 S rRNA sequence analysis, and the results showed that four strains of the isolated bacte-ria were salmonella. The 16 S rRNA sequence analysis of four strains of salmonella showed that the isolates shared more than 99% homology. Drug susceptibility test was performed using paper method, and the results showed that most of the strains were resistant to tilmicosin, cefradine and sul-famethoxazole, but were sensitive to ceftriaxone.

Isolation, Identification and Drug Susceptibility Test of a Strain of Escherichia coli Causing Fox Pneumonia

[Objective] The paper was to determine the pathogen causing fox pneumonia in a breeding factory in Changli County.[Method]Through autopsy, a dominant strain was isolated from the lung of dead foxes, which was then performed Gram staining, 16 S rRNA sequence analysis and biochemical identification.[Result] The strain was negative in Gram staining, and was identified as E. coli through 16 S rRNA sequence analysis and biochemical identification. Drug susceptibility test was conducted using 15 kinds of drug susceptibility papers. The E. coli was sensitive to florfenicol, enrofloxacin, ceftriaxone, norfloxacin;intermediately sensitive to amikacin, gentamicin;and strongly resistant to penicillin, ampicillin,cefradine, sulfamethoxazole, lincomycin, streptomycin and amoxicillin.[Conclusion] It is difficult to treat E. coli causing fox pneumonia with traditional antibiotics clinically.

Dual pH and microbial-sensitive galactosylated polymeric nanocargoes for multi-level targeting to combat ulcerative colitis

Ulcerative colitis(UC)is a type of inflammatory bowel disease characterized by inflammation,ulcers and irritation of the mucosal lining.Oral drug delivery in UC encounters challenges because of multifaceted barriers.Dexamethasone-loaded galactosylated-PLGA/Eudragit S100/pullulan nanocargoes(Dexa-GP/ES/Pu NCs)have been developed with a dual stimuli-sensitive coating responsive to both colonic pH and microbiota,and an underneath galactosylated-PLGA core(GP).The galactose ligand of the GP preferentially binds to the macrophage galactose type-lectin-C(MGL-2)surface receptor.Therefore,both stimuli and ligand-mediated targeting facilitate nanocargoes to deliver Dexa specifically to the colon with enhanced macrophage uptake.Modified emulsion method coupled with a solvent evaporation coating technique was employed to prepare Dexa-GP/ES/Pu NCs.The nanocargoes were tested using in vitro,ex vivo techniques and dextran sodium sulfate(DSS)induced UC model.Prepared nanocargoes had desired physicochemical properties,drug release,cell uptake and cellular viability.Investigations using a DSS-colitis model showed high localization and mitigation of colitis with downregulation of NF-ĸB and COX-2,and restoration of clinical,histopathological,biochemical indices,antioxidant balance,microbial alterations,FTIR spectra,and epithelial junctions’integrity.Thus,Dexa-GP/ES/Pu NCs found to be biocompatible nanocargoes capable of delivering drugs to the inflamed colon with unique targeting properties for prolonged duration.

A comparative study on antimicrobial susceptibility of uroculturome of humans in health and urinary tract infections

Background:The uroculturome indicates the profile of culturable microbes inhabiting the urinary tract,and it is often required to do a urine culture to find an effective antimicrobial to treat urinary tract infections(UTIs).Methods:This study targeted to understand the profile of culturable pathogens in the urine of apparently healthy(128)and humans with clinical UTIs(161)and their antimicrobial susceptibility.All the urine samples were analyzed to quantify microbial load and determine the diversity and antimicrobial susceptibility of microbes following standard microbiological methods.Results:In urine samples from UTI cases,microbial counts were 1.2×10^(4)±6.02×10^(3) colony-forming units(cfu)/mL,while in urine samples from apparently healthy humans,the average count was 3.33±1.34×10^(3) cfu/mL.In eight samples(six from UTI cases and two from apparently healthy people,Candida(C.albicans 3,C.catenulata 1,C.krusei 1,C.tropicalis 1,C.parapsiplosis 1,C.gulliermondii 1)and Rhizopus species(1)were detected.Candida krusei was detected only in a single urine sample from a healthy person and C.albicans was detected both in urine of healthy and clinical UTI cases.Gram-positive(G+ve)bacteria were more commonly(Odds ratio,1.98;CI99,1.01-3.87)detected in urine samples of apparently healthy humans,and Gram-negative(G−ve)bacteria(Odds ratio,2.74;CI99,1.44-5.23)in urines of UTI cases.From urine samples of 161 UTI cases,a total of 90 different types of microbes were detected and,73 samples had only a single type of bacteria.In contrast,49,29,3,4,1,and 2 samples had 2,3,4,5,6 and 7 types of bacteria,respectively.The most common bacteria detected in urine of UTI cases was Escherichia coli(52 samples),in 20 cases as the single type of bacteria,other 34 types of bacteria were detected in pure form in 53 cases.From 128 urine samples of apparently healthy people,88 types of microbes were detected either singly or in association with others,from 64 urine samples only a single type of bacteria was detected while 34,13,3,11,2 and 1 sample yielded 2,3,4,5,6 and seven types of microbes,respectively.In the urine of apparently healthy humans too,E.coli was the most common bacteria,(10 samples)followed by Staphylococcus haemolyticus(9),S.intermedius(5),and S.aureus(5),and similar types of bacteria also dominated in cases of mixed occurrence,E.coli was detected in 26,S.aureus in 22 and S.haemolyticus in 19 urine samples,respectively.G+ve bacteria isolated from urine samples’irrespective of health status were more often(P<0.01)resistant than G−ve bacteria to ajowan oil,holy basil oil,cinnamaldehyde,and cinnamon oil,but more susceptible to sandalwood oil(P<0.01).However,for antibiotics,G+ve were more often susceptible than G−ve bacteria to cephalosporins,doxycycline,and nitrofurantoin.Conclusion:The study concludes that to understand the role of good and bad bacteria in the urinary tract microbiome more targeted studies are needed to discern the isolates at the pathotype level.Further,the study suggests the use of antibiotics by observing good antibiotic stewardship following antibiotic susceptibility testing only.

Susceptibility of Mixed Infection of Ureaplasma Urealyticum and Mycoplasma Hominis to Seven Antimicrobial Agents and Comparison with that of Ureaplasma Urealyticum Infection

In order to investigate the susceptibility of mixed infection of Ureaplasma Urealyticum (UU) and Mycoplasma Hominis (MH) to 7 kinds of antimicrobial agents and comparison with that of UU infection in NGU patients, the in vitro susceptibility was determined by using microdilution method. The positive results were analyzed. The results showed that the sequence of susceptibility to 7 kinds of antimicrobial agents for both UU infection group and UU-MH mixed infection group was almost the same from the highest susceptibility to the lowest accordingly: Josamycin, Doxycycline, Minocycline, Sparfloxacin, Roxithromycin, Ofloxacin and Azithromycin. The total drug resistance rate for UU-MH mixed infection group (97. 67 %) was significantly higher than that for UU infection group (44. 67 %, P<.0. 01). The highest drug resistance rate in UU group and UU-MH mixed infection group was 31. 33 % (Ofloxacin) and 90. 48 % (Azithromycin) respectively. UU-MH mixed infection showed an increased drug resistance and changes of drug resistance spectrum.

Performance of the microscopic observation drug susceptibility assay in pyrazinamide susceptibility testing for Mycobacterium tuberculosis

Background Drug susceptibility assay is very important in tuberculosis therapy. Pyrazinamide is a first line antituberculosis drug and diagnosis of its resistance in Mycobacterium tuberculosis （M. tuberculosis） is difficult and time consuming by conventional methods. In this study, we aimed to evaluate the performance of the microscopic observation drug susceptibility （MODS） assay in the detection of pyrazinamide resistance in M. tuberculosis relative to the conventional Wayne assay and Lowenstein-Jensen （L J） proportion method. Methods M. tuberculosis clinical isolates （n=132） were tested by the MODS and the Wayne assay： the results were compared with those obtained by the LJ proportion method. Mutations in the gene were identified by direct sequencing of the pncA genes of all isolates in which pyrazinamide resistance was detected by any of the three methods. Results Compared to the LJ results, the sensitivity and specificity of the MODS assay were 97.8% and 96.5% respectively; the sensitivity and specificity of the Wayne assay were 87.0% and 97.7% respectively. Mutations in the pncA gene were found in 41 of 46 strains that were pyrazinamide resistant （3 tests）, in 1 of the 4 strains （LJ only）, in 42 of 48 strains （at least I test）, but no mutations in 1 strain sensitive according to the MODS assay only. The MODS assay, Wayne assay and LJ proportion method provided results in a median time of 6, 7 and 26 days respectively. Conclusions MODS assay offers a rapid, simple and reliable method for the detection of pyrazinamide resistance in M. tuberculosis and is an optimal alternative method in resource limited countries.

Prevalence and Anti-Microbial Susceptibility of Methicillin Resistant Staphylococcus aureus at Moi Teaching and Referral Hospital Eldoret

Background: Methicillin-resistant Staphylococcus aureus (MRSA) are pathogens that have major negative impact in all aspects of patient care and are increasingly being recognized as troublesome pathogens in the community. The MRSA are multi-drug resistant bacteria responsible for higher morbidity, mortality and cost of treatment in the affected patients. Research on MRSA antimicrobial susceptibility and resistance in developing countries is limited;hence accurate burden is not certain. Objective: To determine the prevalence and susceptibility pattern of MRSA in S. aureus isolates from patients treated in various units at Moi Teaching and Referral Hospital. Study Design: Cross-sectional design was used to conduct the study. Methods and Materials: Staphylococcus aureus stored isolates from patients at various units at Moi Teaching and Referral Hospital (MTRH) were identified by laboratory conventional methods. Methicillin resistant Staphylococcus aureus was determined using cefoxitin and oxacillin, discs and confirmed by Penicillin Binding Protein (PBP2a’) latex agglutination test. Susceptibility testing was performed according to the Clinical Laboratory Standards Institute procedures. Control strains used were: ATCC 43300 for Methicillin resistant S. aureus (MRSA) strains and ATCC 29213 for methicillin susceptible S. aureus (MSSA) strains. Nine anti-microbials (Erythromycin, Gentamycin, Tetracycline, Vancomycin, Rifampin, Linezolid, Ciprofloxacin, Clindamycin and Fucidicacid) were used to test the anti-microbial susceptibility patterns. Control organisms were run along with the isolates for quality Assurance. The data was analyzed using STATA version 11. Categorical variables were summarized as frequencies and the corresponding percentages. Results were presented using tables and graphs. Results: A total of 107 isolates of S. aureus were obtained, of which 39 (37%) were MRSA. Most of the MRSA, 13 (33%) and 7 (17%), were found in pus and tracheal aspirate samples respectively. Majority of the MRSA isolates were from surgical wards and intensive care unit. The MRSA isolates were highly resistant to erythromycin (92%;36/39) and tetracycline (92% 36/39) and moderately susceptible to linezolid (77% 30/39), Vancomycin (75% 29/39) and fucidic acid (67% 26/39). A total of 28 (74.4%) MRSA isolates were Clindamycin inducible resistant. Conclusions and Recommendations: This study showed that MRSA is a significant pathogen at MTRH. The MRSA were most detected in pus specimens and least in peritoneal aspirates. Routine Screening of S. aureus isolates for MRSA strains at MTRH is therefore imperative. Infection control measures should be put in place to reduce prevalence and prevent the spread of MRSA at MTRH.

Change in molecular weight due to important pfatp6 and pfmdr1 polymorphisms and susceptibility to antimalarial drug:Possible role of epigenetic phenomenon

Malaria is an important tropical mosquito borne infection. It is still the present global public health issue. The management of malaria requires antimalarial drugs. The resistance to antimalarial drugs is a very big problem. The genetic variant is proposed to be an important factor affecting susceptibility to antimalarial drug. Here, the authors studied the change in molecular weight due to important pfatp6 and pfmdr1 polymorphisms and further implied the interrelationship with susceptibility to antimalarial drug. The greatest change can be seen in case of G639D(of pfatp6 polymorphism) while the least change can be seen in the case of N1042D(of pfmdr1 polymorphism). The results from some studies imply that there must be other factors that affect the susceptibility to antimalarial drugs. Those factors might be protein conformation factors, epigenetic factors or environmental factors. Further studies on these aspects should be carried out. It is concluded for possible role of epigenetic phenomenon.

Molecular Characterization and Drug Susceptibility of Mycobacterium Bovis Isolated from Cattle in Xinjiang,China

To the Editor:Bovine tuberculosis (TB)is a zoonotic disease caused by Mycobacterium bovis.It not only seriously influences the raising of livestock but also threatens the health of human beings and other economically important animals.Therefore, the prevention and control of M.boris has great significance for public and animal health.Spoligotyping is the most widely used method for genotyping of M.boris and investigates transmission across different geographical regions.However,its discriminatory power varies widely among countries.Variable number of tandem repeats (VNTR)analysis has emerged as an alternative method for genotyping of bacterial species isolates.

Prevalence and Antimicrobial Susceptibility Pattern of Streptococcus pneumoniae at General Hospital in the Central Region of Japan from December 2013 to February 2014

Streptococcus pneumonia infection is important cause of morbidity and mortality. This study was conducted to find out the prevalence and antimicrobial susceptibility pattern of Streptococcus pneumoniae isolates at general hospitalin the central region of Japan from December 2013 to February 2014. Streptococcus pneumoniae was identified by standard laboratory procedure. Antimicrobial susceptibility testing was performed by micro dilution assay according to CLSI recommendation. One hundred fifty-three Streptococcus pneumoniae were isolated among which 80 (52.2%) were males and 73 (47.8%) were females. Nasal discharge (134%/87.6%) contributed more than other biological materials. The age incidence of (0 - 1) years, (1 - 10) years, (11 - 40) years, (41 - 60) years and >60 years age groups were 26 (17.0%), 110 (71.9%), 3 (2.0%), 10 (6.5%), and 4 (2.6%) respectively. Positive samples were received mostly from the pediatrics (137%/89.5%), respiratory medicine (12%/7.8%) and lowest from gastroenterology (1%/0.6%) and neurology (1/ 0.6%) department. Vancomycin and rifampicin were the most active antibiotics with 100% susceptibility rates. The next best were levofloxacin, penicillin G and ceftriaxone. Our study revealed that 82 Streptococcus pneumonia isolates had multidrug resistant ability (53.6%). Streptococcus pneumoniae infection spreads among community easily and inappropriate use of antibiotics contributes to their resistance. Continuous antimicrobial susceptible surveys are essential to guide policy on the adequate use of antibiotics to reduce the morbidity and mortality and reduce the emergency of antimicrobial resistance.

Microbial Ecology and Antibiotic Susceptibility Profile of Germs Isolated from Hospital Surfaces and Medical Devices in a Reference Hospital in Douala (Cameroon)

Background: The hospital environment is largely contaminated with pathogenic microorganisms. This colonization is a threat for hospitalized patients, especially in high-risk services. The purpose of this study was to identify the germs found on surfaces and medical devices in some departments of the General Hospital of Douala, and to establish their susceptibility profile to most commonly used antibiotics in this health facility. Results: We collected 114 surface and medical device samples, and seeded different culture media for Gram-positive and Gram-negative aerobic bacteria. Of the total samples, 108 were positive and 137 bacterial strains were isolated. The colony count revealed a high rate of contamination. Enterobacter cloacae was the most represented specie (53.3%), followed by Pseudomonas aeruginosa (22.6%) and Klebsiella pneumoniae (6.6%). Various coagulase-negative Staphylococci have been isolated in some departments, as well as Cryptococcus laurentii and molds. The isolated strains showed low susceptibility to the antibiotics tested. Enterobacter cloacae showed low susceptibility for all tested molecules, except for carbapenems with rates ranging from 82% to over 94% in Maternity, Intensive Care and Neonatology units. The strains coming from the Haematology Protected Ward were resistant to all antibiotics, except fluoroquinolones with a susceptibility rate of 50% for ofloxacin. Conclusion: The hospital surfaces and medical devices are highly contaminated by environmental bacteria, with low susceptibility rates to antibiotics. Microbiological controls of the environment should be regular in critical areas in order to reinforce measures to prevent diffusion of multi-resistant bacteria.

Fractional-Order Model for Multi-Drug Antimicrobial Resistance

Drug resistance is one of the most serious phenomena in financial,economic and medical terms.The present paper proposes and investigates a simple mathematical fractional-order model for the phenomenon of multi-drug antimicrobial resistance.The model describes the dynamics of the susceptible and three kinds of infected populations.The first class of the infected society responds to the first antimicrobial drug but resists to the second one.The second infected individuals react to the second antimicrobial drug but resist to the first one.The third class shows resistance to both of the two drugs.We formulate the model and associate it with some of its properties.The stability conditions of the multi-drug antimicrobial resistance equilibrium states are derived.We illustrate the analytical results by some numerical simulations.

Microbial Assessment and Antibiotic Susceptibility Profile of Bacterial Fish Isolates in an Aquaculture Production Site in Mefou Afamba Division of Cameroon

The practice of integrated fish farming and the use of local fish meal and manure for fish feeding in Cameroon constitute potential sources of resistant pathogenic bacteria in the fish pond environment.Therefore,a periodical and constant monitoring of the microbiological quality of fish pond is imperative.This study was to assess the microbial contamination of Mfou aquaculture production site and evaluate the antibiotic resistance profile of bacterial fish isolates.Samples of pond water(n=36),sediment(n=36),fishmeal(n=12)and African catfish(Clarias gariepinus),kanga(Heterotis niloticus)and Nile Tilapia(Oreochromis niloticus)(n=36,each)were collected to determine TVAC(Total Viable Aerobic Bacterial Count),FC(Fungal Count),SAC(Staphylococcus aureus count),TCC(Total Coliform Count)and FCC(Feacal Coliform Count).The fish skin isolates of S.aureus,Enterobacter sakazakii,Citrobacter freundii,Serratia fonticola,Klebsiella oxytoca,Proteus spp.,Aeromonas hydrophila,Kluyvera spp.,Moraxella spp.,Pasteurella multocida and Pseudomonas fluorescens were tested against penicillin G(10μg),chloramphenicol(30μg),sulfamethoxazole/trimethoprim(25μg),erythromycin(15μg),tetracycline(30μg),using the disk diffusion method.Results reveal a heavy contamination of fish farms with microbial load above the recommended limits.Our study indicates that fish ponds are sources of zoonotic pathogens underlining their epidemiological and clinical relevance.All bacterial isolates were multiresistant with a multiple antibiotic resistance index above 0.2.These data raise concern about the microbial contamination of aquaculture and associated public health risks in Cameroon.

Antimicrobial Susceptibility Profiles among <i>Escherichia coli</i>Strains Isolated from Athi River Water in Machakos County, Kenya

Antimicrobial use in agriculture, livestock and human health has increased over the years leading to the increase in antimicrobial resistance that can also find its way to the aquatic environment. Rivers can act as reservoirs of highly resistant strains and facilitate the dissemination of multidrug resistant (MDR) strains to animals and humans using water. A total of 318 water samples were collected from six different sampling points along Athi River and E. coli isolates were subjected to Kirby-Bauer diffusion method for antimicrobial susceptibility testing. The total mean coliform count of the sampled sites was 2.7 × 104 (cfu/mL). E. coli isolates were most resistant to ampicillin (63.8%) and most susceptible to gentamicin (99.4%). MDR strains (resistance to ≥3 classes of antibiotics) accounted for 65.4% of all the isolates. The site recorded to have human industrial and agricultural zone activities had strains that were significantly more resistant to ampicillin, cefoxitin, amoxicillin/clavulanic acid (P ≤ 0.05) than isolates from the section of the river traversing virgin land and land with minimum human activities. This study indicates that E. coli strains isolated from Athi River were highly MDR and most resistant to some antimicrobial classes (ampicillin and cefoxitin) which constitute a potential risk to human and animal health.

Prevalence, Antimicrobial Susceptibility Pattern and Factors Associated with GBS Colonization in Pregnant Women at the Regional Hospital Bamenda (RHB)

Introduction: Maternal asymptomatic colonization with GBS (Group-B Streptococcus) has become a major cause of sepsis, meningitis and encephalopathy in neonates alongside premature births, stillbirths and post-natal infections. Routine screening of pregnant women for GBS carriage and antimicrobial susceptibility are therefore necessary. This study was aimed at evaluating the prevalence, antimicrobial susceptibility pattern and factors associated with GBS colonization in pregnant women at the Regional Hospital Bamenda (RHB). Materials and Methods: Vaginal and rectal swab samples were collected from 121 pregnant women in the 3rd trimester at the RHB from December 2017 to May 2018. Sociodemographic, obstetric and neonatal history and some clinical parameters were obtained through a questionnaire approach. Cultures for the isolation and identification of GBS from the samples were done and grouping as well as susceptibility testing of GBS isolates was done. Results: The colonisation rates were 5.8% (7), 1.7% (2) and 5.8% (7) for rectal, vaginal and concomitant recto-vaginal carriage. GBS was isolated in the vagina/rectum of 16 participants (13.2% prevalence). Of the 16 GBS strains used for in vitro susceptibility test, no resistance to ampicillin, oxacillin, amoxicillin-clavulanate, ceftriaxone, erythromycin, imipenem, aztreonam and clindamycin was recorded. 6.3% (1) of the strains had intermediate susceptibility to ampicillin and amoxicillin-clavulanic acid. Of the isolates examined, 37.5% (6), and 12.5% (2) were respectively sensitive to gentamycin and levofloxacin. Maternal overweight, HIV positive status, history of PROM and spontaneous abortion, presence of Gardnerella vaginalis and Candida albicans had a high rate of GBS colonization but only HIV positive status had a statistical significance (p = 0.01). Other microbes isolated were Gardnerella vaginalis (55.4%, 67), Candida albicans (40.5%, 49), and Candida spp (12.4%, 15). Conclusion: GBS prevalence was 13.2%. GBS had decreased susceptibility to some antibiotics. Only HIV positive status was significantly associated with GBS colonization.

蜥蜴源黏质沙雷氏菌的分离鉴定与药敏试验

为弄清西北农林科技大学博览园1只观赏蜥蜴突发全身皮肤化脓溃烂、尾巴坏死脱落的病原,采集患病蜥蜴的坏死病灶及血液病料进行细菌分离纯化、生理生化试验、动物致病性试验、16S rRNA基因测序鉴定。结果显示,从病料中分离并纯化出1株菌株,该分离菌株的生理生化特性与黏质沙雷氏菌相符,且该菌对实验小鼠有致病性,其16S rRNA基因序列与NCBI中黏质沙雷氏菌的参考序列同源性为98%。结果表明,所分离到的菌株为黏质沙雷氏菌。药敏试验结果显示,分离菌株对诺氟沙星、丁胺卡那、头孢曲松、氧氟沙星、头孢噻肟等5种抗菌药物高度敏感,对复方新诺明中度敏感,对环丙沙星、头孢噻吩、庆大霉素、头孢氨苄、苯唑西林、多黏菌素B、林可霉素、四环素、氨苄西林等9种抗菌药物耐药。研究结果为筛选有效治疗药物提供了参考依据。

Isolation,identification,and virulence gene analysis of pathogenic Aeromonas dhakensis in Macrobrachium rosenbergii and histopathological observation

To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.