Standard Control Strains Research Articles

Crystal violet decolorization assay: a simplified colorimetric test for the rapid detection of multidrug-resistant Mycobacterium tuberculosis isolates

The increased prevalence of multi-drug resistant M. tuberculosis is quite possibly the direst and most difficult task for the early diagnosis and treatment. A rapid, reliable, and inexpensive diagnostic method is the need of the hour. The current study on crystal violet decolorization assay explores the possibility to develop a rapid and simple detection method to detect multi-drug-resistant tuberculosis isolates by comparing the results with the traditional liquid culture drug susceptibility testing method based on their sensitivity, specificity, positive predictive value, and negative predictive value. 70 isolates were used for the study and were detected as multi-drug resistant, mono drug-resistant, and sensitive by using crystal violet decolourization assay and further compared with the results of DST and using H37Rv as the standard control strain. The sensitivity, specificity, positive predictive value, and negative predictive value of crystal violet decolorization assay (Rifampicin: 100%, 94.60%, 100% and 82.40%; isoniazid: 100%, 94.10%, 100%, 86.40%) are calculated and the percentage were compared with the conventional liquid culture drug susceptibility testing for M. tuberculosis using rifampicin and isoniazid. Crystal violet decolourization assay is rapid, reproducible, and doesn't require any highly experienced personal or sophisticated laboratory instruments for interpretation. This assay is found to be nearly as reliable as conventional liquid culture drug susceptibility testing and may thus be of great help in phenotypic confirmation of multi-drug resistant tuberculosis by providing results more rapidly.

Determination of Antibacterial Activity of St. John's Wort (Hypericum perforatum L.) Oil, Nigella Sativa Oil, Clove (Eugenia caryophyllata) Oil, Orange Peel (Citrus sinensis) and Garlic (Allium sativa) Oil Against Microorganisms Isolated From Clinical Samples

Objective: The aim of this study is to detect St. John's Wort, Nigella sativa, Clove, Orange Peel and Garlic oil on bacteria isolated from blood culture to determine its antibacterial effect.
 Methods: One hundered blood samples sent to … Medical Microbiology Laboratory between 1 June 2021 and 1 January 2022 were analyzed with blood culture system. Bacteria isolated from blood culture were passaged into blood agar. Bacterial suspension was prepared from the bacterial colonies at 0.5 Mc Farland turbidity. In order to determine the antibacterial activity of plant extract oils, Minimum Inhibition Concentration and Minimal Bactericidal Concentration values were determined by liquid microdilution method. Also, the zone diameters of the disc diffusion method were measured.
 Results: The antibacterial effect of plant extract oils was detected on only 10 of the 100 clinical samples included in the study. St. John's Wort oil used in these 10 samples showed the most effective antibacterial effect of 7.81 µg/mL against Staphylococcus haemolyticus and Enterobacter aerogenes. Garlic oil showed the most effective antibacterial effect against Escherichia coli and Staphylococcus haemolyticus at 7.81 µg/mL. Nigella sativa oil showed the most effective antibacterial effect against Staphylococcus haemolyticus at 3.9 µg/mL. Orange Peel oil showed the most effective antibacterial effect against Enterococcus faecalis
 at 1.95 µg/mL. The minimum inhibition concentration at which the oils were effective on microorganisms was determined by comparing them with standard control strains. 
 Conclusion: More clinical isolates and high-dose studies are needed to determine the effectiveness of plant extract oils. Garlic oil Escherichia coli, Staphylococcus haemolyticus and Enterobacter aerogenes, St. John's wort oil Staphylococcus haemolyticus and Enterobacter aerogenes, Nigella sativa) oil on Staphylococcus haemolyticus has been found to be effective

Characterization of a bacterial strain Lactobacillus paracasei LP10266 recovered from an endocarditis patient in Shandong, China

BackgroundLactobacilli are often recognized as beneficial partners in human microbial environments. However, lactobacilli also cause diseases in human, e.g. infective endocarditis (IE), septicaemia, rheumatic vascular disease, and dental caries. Therefore, the identification of potential pathogenic traits associated with lactobacilli will facilitate the prevention and treatment of the diseases caused by lactobacilli. Herein, we investigated the genomic traits and pathogenic potential of a novel bacterial strain Lactobacillus paracasei LP10266 which has caused a case of IE. We isolated L. paracasei LP10266 from an IE patient’s blood to perform high-throughput sequencing and compared the genome of strain LP10266 with those of closely related lactobacilli to determine genes associated with its infectivity. We performed the antimicrobial susceptibility testing on strain LP10266. We assessed its virulence by mouse lethality and serum bactericidal assays as well as its serum complement- and platelet-activating ability. The biofilm formation and adherence of strain LP10266 were also studied.ResultsPhylogenetic analysis revealed that strain LP10266 was allied with L. casei and L. paracasei. Genomic studies revealed two spaCBA pilus clusters and one novel exopolysaccharides (EPS) cluster in strain LP10266, which was sensitive to ampicillin, penicillin, levofloxacin, and imipenem, but resistant to cefuroxime, cefazolin, cefotaxime, meropenem, and vancomycin. Strain LP10266 was nonfatal and sensitive to serum, capable of activating complement 3a and terminal complement complex C5b-9 (TCC). Strain LP10266 could not induce platelet aggregation but displayed a stronger biofilm formation ability and adherence to human vascular endothelial cells (HUVECs) compared to the standard control strain L. paracasei ATCC25302.ConclusionThe genome of a novel bacterial strain L. paracasei LP10266 was sequenced. Our results based on various types of assays consistently revealed that L. paracasei LP10266 was a potential pathogen to patients with a history of cardiac disease and inguinal hernia repair. Strain LP10266 showed strong biofilm formation ability and adherence, enhancing the awareness of L. paracasei infections.

Status and problems of bacteriological diagnosis of diphtheria infection in the Russian Federation.

The purpose of the work was to assess the state of bacteriological diagnosis of diphtheria infection in Russia in order to establish possible reasons for the decrease in the release of C. diphtheriae. The Reference Center for Monitoring the Pathogens of Measles, Rubella, Mumps, Pertussis and Diphtheria in 2018 in 85 subjects of Russia conducted a questionnaire of laboratories of medical organizations and the Centers for Hygiene and Epidemiology of Rospotrebnadzor, carrying out bacteriological studies for diphtheria infection. It was found that the number of studies conducted over the five-year period decreased by 1.2 times. The tendency to decrease the number of bacteriological studies for diphtheria is observed in the territories of almost all federal districts. In 99% and 29% of cases, the institutions of the FBUZ Centers for Hygiene and Epidemiology and medical organizations (MO) and use in their work documents regulating bacteriological studies for diphtheria infection. In a number of territories, the list of documents used includes documents that are invalid or do not define such studies. Most organizations use dry tampons when examining for diphtheria, however, 13.1% and 53.4% of FBUZ Centers for Hygiene and Epidemiology and medical organizations (respectively) use commercial transport environments, which does not comply with regulatory documentation. Analysis of the quality of work of bacteriological laboratories showed shortcomings at the stage of preparation of media (use of donor blood, or absence of addition of blood and potassium tellurite), Elek tests (addition of horse serum or absence of serum to the medium), setting of incomplete biochemical series (absence of tests for urease and nitrate reductase), absence of standard control strains, incomplete volume of internal laboratory quality control. Given the continuing circulation of the pathogen in various countries of the world and in our country, as well as the possibility of imported cases of infection from endemic regions, the analysis was aimed at drawing the attention of specialists to the problem of improving the quality of laboratory diagnosis of diphtheria in Russia.

Evaluation of Selected Pakistani Honeys in Comparison with Manuka Honey Against Vibrio cholerae

Background: Antibacterial resistance in Vibrio cholerae has been reported in many parts of the world. Therefore, it is important to explore novel therapies which stand less chances of developing antimicrobial resistance. In this regard honey is getting worldwide attention because antibacterial resistance against honey is unlikely.
 Objectives: To determine the antibacterial activity of locally produced Sidr (Ziziphus jujuba), Kalonji (Nigella sativa) and Eucalyptus (Eucalyptus spp) honey against twenty-six clinical isolates of Vibrio cholerae to compare the antibacterial activity of indigenous honey with medically graded Manuka honey.
 Methodology: Identification of Vibrio cholerae was done by standard cultural, biochemical and serological methods. Susceptibility pattern of Vibrio cholerae was also determined. Minimum inhibitory concentrations (MIC) of locally produced Sidr, Kalonji and Eucalyptus honey, and medically graded Manuka honey was determined by agar dilution and kirby bauer test. American Type Culture Collections (ATCC) Escherichia coli 25922, Staphylococcus aureus 25923 and Acinetobacter baumannii 29213 were used as standard control strains.
 Results: Manuka and Eucalyptus honey have comparable antibacterial activity against both sensitive and resistant clinical isolates of Vibrio cholerae. The lowest MICs were between 3.7 to 4% for medically graded Manuka honey, whereas Eucalyptus honey inhibited between the range 4 to 4.3%. Kalonji and Sidr honey inhibited these isolates between 6.7 to 7.0% and 6.3 to 7.0%, respectively.
 Conclusion: It is concluded that Manuka and Eucalyptus honey could be evaluated in a clinical trial for the treatment of gastroenteritis caused by Vibrio cholerae.

Development of in-vitro Sensitivity Testing for Pathogenic Bacteria

A new method developed for in-vitro susceptibility test in medical laboratories consist of micro tubes or gloves containing dehydrated tryptic soya broth, 5% glucose, 0.1% bromothymol blue and one type of antibiotics (ampicillin, tetracycline and chloramphenicol) with critical concentration MIC (minimum inhibitory concentration) for susceptibility. Standard quality control strains of bacterial (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) suspension were adjusted to 0.5 McFarland turbidity standard (1 × 106 cell/mL) were used in inoculation the media and incubated two hours at 37 °C. The MIC of ampicillin against E. coli, S. aureus, and P. aeruginosa were 4, 32, and 256 µg/mL of the media for the bacteria respectively, while the MIC of tetracycline against bacteria were 512, 512 and 32 µg/mL respectively, the MIC of chloramphenicol were 512, 32 and 512 µg/mL, respectively. Where, the resistant bacteria to the antibiotics could grow and ferment glucose sugar producing a color change of the media from blue to yellow, while the sensitive bacteria do not grow or show no change in color. Our study result compared with common used antibiotic disk method obtaining similar results. This developed method characterized by fast (only two hours) and less cost in comparison to conventional technique. The new micro tube strip is highly stable (more than one year) with more sensitive in detection of variable pathogenic bacteria including standard bacteria strains compared with conventional technique..

Development of in-vitro Sensitivity Testing for Pathogenic Bacteria

A new method developed for in-vitro susceptibility test in medical laboratories consist of micro tubes or gloves containing dehydrated tryptic soya broth, 5% glucose, 0.1% bromothymol blue and one type of antibiotics (ampicillin, tetracycline and chloramphenicol) with critical concentration MIC (minimum inhibitory concentration) for susceptibility. Standard quality control strains of bacterial (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) suspension were adjusted to 0.5 McFarland turbidity standard (1 × 106 cell/mL) were used in inoculation the media and incubated two hours at 37 °C. The MIC of ampicillin against E. coli, S. aureus, and P. aeruginosa were 4, 32, and 256 µg/mL of the media for the bacteria respectively, while the MIC of tetracycline against bacteria were 512, 512 and 32 µg/mL respectively, the MIC of chloramphenicol were 512, 32 and 512 µg/mL, respectively. Where, the resistant bacteria to the antibiotics could grow and ferment glucose sugar producing a color change of the media from blue to yellow, while the sensitive bacteria do not grow or show no change in color. Our study result compared with common used antibiotic disk method obtaining similar results. This developed method characterized by fast (only two hours) and less cost in comparison to conventional technique. The new micro tube strip is highly stable (more than one year) with more sensitive in detection of variable pathogenic bacteria including standard bacteria strains compared with conventional technique..

Simple detection of bacterioplankton using a loop-mediated isothermal amplification (LAMP) assay: First practical approach to 72 cases of suspected drowning

We developed a novel molecular tool for assisting the diagnosis of death by drowning and evaluated its validity in forensic practical cases. Two novel sets of loop-mediated isothermal amplification (LAMP) primers were designed to detect either representative freshwater (Aeromonas) or marine (Vibrio, Photobacterium, Listonella) bacterioplankton (aquatic bacteria) in one tube using the LAMP technique. The assay involves only mixing template DNA with seven reagents and incubating at 64°C for 80min and does not require special or expensive equipment because detection is based on visual observation under natural light. The assay’s excellent specificity was also demonstrated using 17 standard (control) strains and 124 other bacterial strains cultured from drowning and non-drowning victims in our previous studies. We then assayed 299 specimens (135 lung, 164 blood) from 72 victims, including 45 who had drowned in rivers, ditches, seas, and around estuaries. LAMP assay results could provide effective information to assist the diagnosis of death by drowning in practical cases. The LAMP assay would be useful for suspected drowning cases, as it is a less-laborious and less-expensive minimal test when death by drowning is sufficiently confirmed or negated from only autopsy findings and environmental data or when diatom testing is not performed due to logistic, personnel, or budgetary limitations. Moreover, the assay could serve as a simple additional test when the density of diatoms in the lungs is very low due to low density in the water.

Whole transcriptome analysis reveals potential novel mechanisms of low-level linezolid resistance in Enterococcus faecalis

Linezolid is an oxazolidinone antibiotic commonly used to treat serious infections caused by vancomycin-resistant enterococcus. Recently, low-level linezolid resistant Enterococcus faecalis strains have emerged worldwide, but the resistant mechanisms remain undefined. Whole-transcriptome profiling was performed on an E. faecalis strain P10748 with low-level linezolid resistance in comparison with a linezolid-susceptible strain 3138 and the standard control strain ATCC29212. The functions of differentially expressed genes (DEGs) were predicted, with some DEGs potentially involved in drug resistance were validated by PCR and quantitative PCR (qPCR). RNA-Seq on three E. faecalis strains generated 1920 unigenes, with 98% of them assigned to various function groups. A total of 150 DEGs were identified in the linezolid resistant strain P10748 compared to the linezolid susceptible strains 3138 and ATCC29212. Functional analysis indicated a significant transcriptomic shift to membrane transportation and biofilm formation in strain P10748, with three significantly up-regulated DEGs predicted to be associated with drug resistance through active efflux pumps and biofilm formation. The existence of these three DEGs was further confirmed by PCR and qPCR. The significant upregulation of genes associated with efflux pumps and biofilm formation in the linezolid resistant strain suggests their roles in low-level resistance to linezolid in E. faecalis.

Experimental Germ Tube Induction in Candida albicans: An Evaluation of the Effect of Sodium Bicarbonate on Morphogenesis and Comparison with Pooled Human Serum.

Objective The potential of NaHCO3 versus human serum to induce germ tube formation in Candida albicans was investigated. Specimens A total of 100 isolates were obtained from oral swabs of patients presenting with thrush. Approval for the study was granted by the Joint Research Ethics Committee (JREC/23/08). Method Confirmed C. albicans isolates by routine methods were tested for germ tube induction using 5 different concentrations of Tris-maleate buffered NaHCO3 and Tris-maleate buffer control. Standard control strains included were C. albicans (ATCC 10231) and C. krusei (ATCC 6258). Microculture was done in 20 μL inoculums on microscope slides for 3 hours at 37°C. The rate of germ tube formation at 10-minute intervals was determined on 100 isolates using the optimum 20 mM Tris-maleate buffered NaHCO3 concentration. Parallel germ tube formation using human serum was done in test tubes. Results The optimum concentration of NaHCO3 in Tris-maleate buffer for germ tube induction was 20 mM for 67% of isolates. Only 21% of isolates formed germ tubes in Tris-maleate buffer control. There was no significant difference in induction between human serum and Tris-maleate buffered NaHCO3. Conclusion Tris-maleate buffered NaHCO3 induced germ tube formation in C. albicans isolates at rates similar to human serum.

Draft Genome Sequence of a vanA-Type Vancomycin-Resistant Reference Strain, Enterococcus faecium ATCC 51559.

Vancomycin-resistant Enterococcus faecium has emerged as a multidrug-resistant pathogen in hospital settings. Here, we present the draft genome sequence of a high-level vancomycin-resistant strain, E. faecium ATCC 51559, which is employed as a standard laboratory vanA genotype-positive control strain for clinical and laboratory studies.

Effect of social odor context on the emission of isolation-induced ultrasonic vocalizations in the BTBR T+tf/J mouse model for autism.

An important diagnostic criterion for social communication deficits in autism spectrum disorders (ASD) are difficulties in adjusting behavior to suit different social contexts. While the BTBR T+tf/J (BTBR) inbred strain of mice is one of the most commonly used mouse models for ASD, little is known about whether BTBR mice display deficits in detecting changes in social context and their ability to adjust to them. Here, it was tested therefore whether the emission of isolation-induced ultrasonic vocalizations (USV) in BTBR mouse pups is affected by the social odor context, in comparison to the standard control strain with high sociability, C57BL/6J (B6). It is known that the presence of odors from mothers and littermates leads to a calming of the isolated mouse pup, and hence to a reduction in isolation-induced USV emission. In accordance with their behavioral phenotypes with relevance to all diagnostic core symptoms of ASD, it was predicted that BTBR mouse pups would not display a calming response when tested under soiled bedding conditions with home cage bedding material containing maternal odors, and that similar isolation-induced USV emission rates would be seen in BTBR mice tested under clean and soiled bedding conditions. Unexpectedly, however, the present findings show that BTBR mouse pups display such a calming response and emit fewer isolation-induced USV when tested under soiled as compared to clean bedding conditions, similar to B6 mouse pups. Yet, in contrast to B6 mouse pups, which emitted isolation-induced USV with shorter call durations and lower levels of frequency modulation under soiled bedding conditions, social odor context had no effect on acoustic call features in BTBR mouse pups. This indicates that the BTBR mouse model for ASD does not display deficits in detecting changes in social context, but has a limited ability and/or reduced motivation to adjust to them.

Evidence for reduced tonic levels of GABA in the hippocampus of an animal model of ADHD, the spontaneously hypertensive rat

Recent studies have investigated the role of γ-aminobutyric acid (GABA) in the behavioural symptoms of attention-deficit/hyperactivity disorder (ADHD), specifically in behavioural disinhibition. Spontaneously hypertensive rats (SHR) are widely accepted as an animal model of ADHD, displaying core symptoms of the disorder. Using an in vitro superfusion technique, we have shown that glutamate-stimulated release of radio-actively labelled norepinephrine ([3H]NE) from prefrontal cortex and hippocampal slices is greater in SHR than in their normotensive control strain, Wistar-Kyoto rats (WKY), and/or a standard control strain, Sprague-Dawley rats (SD). In the present study, we investigated how the level of extracellular (tonic) GABA affects release of [3H]NE in hippocampal slices of male and female SHR, WKY and SD rats, in response to 3 glutamate stimulations (S1, S2, and S3). The hippocampal slices were prelabelled with [3H]NE and superfused with buffer containing 0μM, 1μM, 10μM, or 100μM GABA. Three consecutive glutamate stimulations were achieved by exposing slices to 3 pulses of glutamate (1mM), each separated by 10min. Increasing tonic levels of GABA increased basal and stimulated release of [3H]NE in all strains. When GABA was omitted from the superfusion buffer used to perfuse SHR hippocampal slices, but present at 100µM in the buffer used to perfuse WKY and SD hippocampal slices, glutamate-stimulated release of [3H]NE was similar in all three strains. In these conditions, the decrease in [3H]NE release from S1 to S2 and S3 was also similar in all three strains. These findings suggest that extracellular concentrations of GABA may be reduced in SHR hippocampus, in vivo, compared to WKY and SD. An underlying defect in GABA function may be at the root of the dysfunction in catecholamine transmission noted in SHR, and may underlie their ADHD-like behaviours.

P2.098 Speciation and Antifungal Susceptibility Testing of Candida Species Causing Oral Thrush in HIV Patients

PurposeOral thrush by Candida species is a common ailment of individuals suffering from HIV infection. These species show a high resistance to antifungal drugs used for the treatment. Hence our...

English

 The present study describes the chemical composition and antimicrobial activity of essential oil from Salvia potentillifolia Boiss. & Heldr. ex Benth., which is endemic for Turkey. The essential oil was obtained by hydrodistillation and components of the essential oil were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The major components of S. potentillifolia essential oil were 1.8-cineole (19.33%), b-pinene (11.97%) and a-pinene (8.99%). Antimicrobial activity of the essential oil was investigated against standard control and resistant strains, using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. The essential oil of S. potentillifolia showed relatively low levels of antimicrobial activity against the bacteria tested. However, the oil was as effective as the antibiotic tested againstStaphylococcus aureus ATCC 29213, Staphylococcus aureus ATCC 43300 [methicillin resistant Staphylococcus aureus (MRSA)], Enterococcus faecalis ATCC 51299 [vancomycin resistant Enterococcus faecalis (VRE)], Enterococcus faecalis ATCC 29212, Haemophilus influenzae ATCC 49247 strains. The most bactericidal activity was obtained against Haemophilus species (4 μg/ml).   Key words: Salvia, lamiaceae, essential oil, GC-MS analysis, antimicrobial effect, MRSA,VRE 

Chemical Composition and Antimicrobial Activity of Essential Oil of Endemic Origanum bilgeri P. H. Davis for Turkey

The present study describes chemical composition and antimicrobial activity of the essential oil from Origanum bilgeri, which is endemic for Turkey. The essential oil was obtained by hydrodistillation and components of the essential oil were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The major component of O. bilgeri essential oil was carvacrol (84.8 %) and p-cymene (4.0 %), γ-terpinene (3.3 %) were the other components. Antimicrobial activity of the essential oil was investigated against standard control and resistant strains, using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. O. bilgeri essential oil showed very strong antimicrobial activity against all tested pathogenic bacteria except P. aeruginosa. Especially, it is important that the essential oil was more effective than antibiotics tested against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus faecalis (VRE).

Crude Ethanolic Extracts ofGarcinia kolaSeeds Heckel (Guttiferae) Prolong the Lag Phase ofHelicobacter pylori: Inhibitory and Bactericidal Potential

Problems associated with current treatment regimens have generated a considerable interest in alternative approaches for the eradication of Helicobacter pylori infections using phytochemical compounds. In an attempt to identify potential sources of such compounds, the antimicrobial activity of five solvent extracts of Garcinia kola seeds were investigated against 30 clinical strains of H. pylori and a standard control strain, NCTC 11638, using standard microbiological techniques. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. All the extracts tested exhibited anti-H. pylori activity with zone diameters of inhibition between 0 and 25 mm. The ethanol extract demonstrated considerable anti-H. pylori activity with a percentage susceptibility of 53.3% and minimum inhibitory concentration for 50% susceptibility (MIC₅₀) values ranging from 0.63 to 5.0 mg/mL. Ranges of MIC₅₀ values for amoxicillin and metronidazole were 0.01-0.63 mg/mL and 0.04-5.0 mg/mL, respectively. The inhibitory activity of the ethanol extract was similar to that of metronidazole (P > .05) as opposed to amoxicillin (P < .05). The extract caused a 12-hour extension of the lag phase of H. pylori at 1.25 mg/mL. The same observations were recorded when this concentration was doubled and quadrupled alongside a killing rate of 80.1% and 93.7%, respectively, after 24 hours and of 100% after 30 hours. These results demonstrate that the ethanol extract of G. kola may contain therapeutically useful compounds against H. pylori.

Reduced scent marking and ultrasonic vocalizations in the BTBR T+tf/J mouse model of autism.

Qualitative impairments in communication, such as delayed language and poor interactive communication skills, are fundamental to the diagnosis of autism. Investigations into social communication in adult BTBR T+tf/J (BTBR) mice are needed to determine whether this inbred strain incorporates phenotypes relevant to the second diagnostic symptom of autism, communication deficits, along with its strong behavioral phenotypes relevant to the first and third diagnostic symptoms, impairments in social interactions and high levels of repetitive behavior. The aim of the present study was to simultaneously measure female urine-elicited scent marking and ultrasonic vocalizations in adult male BTBR mice, in comparison with a standard control strain with high sociability, C57BL/6J (B6), for the assessment of a potential communication deficit in BTBR. Adult male BTBR mice displayed lower scent marking and minimal ultrasonic vocalization responses to female urine obtained from both B6 and BTBR females. Lower scent marking and ultrasonic vocalizations in a social setting by BTBR, as compared with B6, are consistent with the well-replicated social deficits in this inbred mouse strain. Our findings support the interpretation that BTBR incorporate communication deficits, and suggest that scent marking and ultrasonic vocalizations offer promising measures of interest in social cues that may be widely applicable to investigations of mouse models of autism.

Metabolism and excretion kinetics of 14C-labeled and non-labeled difloxacin in pigs after oral administration, and antimicrobial activity of manure containing difloxacin and its metabolites

Fluoroquinolones are amongst the most important antibiotics used in veterinary medicine. On this account the behavior of difloxacin (DIF) and its metabolites was investigated by administering the 14C-labeled and non-labeled veterinary drug to fattening pigs. The excretion kinetics were determined after daily collection of manure. Sarafloxacin (SAR) was found to be the major metabolite, three further trace metabolites were also recovered, applying high-resolution (HR) mass spectrometric technique. The identification of DIF and SAR was confirmed by comparison with the spectroscopic and chromatographic data of the authentic references. The identification of the three trace metabolites was performed by HR-MS/MS. Only 8.1% of the administered radioactivity remained in the pig after 10 days and DIF accounted for 95.9% of the radioactivity excreted. More than 99% of the labeled compounds were detected and identified in the manure. The mean recoveries for all single electrolytes were ⩾94%. Linearity was established over concentration range 10–10,000 μg/kg manure with a correlation coefficient ⩾0.99. By using in vitro antimicrobial activity tests against a group of standard pathogenic control strains, the results showed that the residual antibiotic concentrations in the manure of pigs are high enough to exhibit antibacterial activity.

Detection and analysis of antibiotic resistance of Salmonella from retail meats in some districts of Shaanxi province

Salmonella isolates recovered from retail meats that were collected in supermarkets and free markets in Xi'an and Yangling areas of Shaanxi province were studied to determine antibiotic susceptibility. Antimicrobial susceptibility to 14 antibiotics of 193 salmonella isolates were determined by using agar dilution method, which was recommended by National Committee of Clinical Laboratory Standard (NCCLS), and E.coli ATCC25922 and E.faecalis ATCC29212 as standard control strains. The 44.6% of the salmonella isolates were resistant to sulfamethoxazole, followed by resistance to kanamycin (40.9%), tetracycline (37.8%), amoxicillin (26.9%), ampicillin (25.4%), gentamicin (23.3%) and chloramphenicol (21.8%). Some isolates also showed resistance to fluoroquinolones, the rates for ciprofloxacin, enrofloxacin, levofloxacin and gatifloxacin were 22.3%, 21.8%, 20.8% and 21.2%, respectively. 55 isolates (28.5%) were multidrug resistant (MDR) strains, 28 of 193 isolates (14.5%) could resist at least 13 antibiotics, 24 isolates (12.4%) were resistant to from 4 to 12 antibiotics. Salmonella isolates recovered from retail meats in Xi'an district of Shaanxi province were seriously resistant to antimicrobials commonly used as human and veterinary medicine.