We evaluated the effects of different levels of DON (LD 441 and HD 1223 μg DON/kg in diet) on the growth performance, immunity, reproductive hormones, and intestinal health of immature gilts. No significant differences were observed in average daily gain, average daily feed intake, or feed to gain ratio between the LD group and the HD group (p > 0.05). The red blood cell count and hematocrit were higher in the LD group compared with the HD group on d 21 (p < 0.05). The gamma-glutamyl transferase activity in the LD group on d 1, 21, 28, 35, and 42 was higher (p < 0.05) compared with the HD group. The aspartate aminotransferase, total antioxidant capacity, and lactic dehydrogenase levels on d 35 were higher in the LD group than those in the HD group (p < 0.05). On d 35, the levels of interleukin 1β, interleukin-4, interleukin-10, tumor necrosis factor-α, and interferon-γ in LD were higher than those in the HD group (p < 0.05). The levels of immunoglobulin A, immunoglobulin M, immunoglobulin G, and complement 4 on d 35 were higher in the LD group compared with those in the HD group (p < 0.05). The gonadotrophin-releasing hormone, luteotrophic hormone, follicle-stimulating hormone, or estradiol did not differ between LD and HD groups throughout the experiment (p > 0.05). For fecal microbiota, Streptococcus in the HD group was reduced compared with the LD group (p < 0.05). In summary, feeding diets contaminated with 1223 μg DON/kg exerted adverse effects on serum profiles of gilts but did not affect their growth performance or reproductive hormones in the present study.

Sow endometritis is usually caused by multiple species of pathogenic bacteria. Numerous isolates from endometritis patients have developed antimicrobial resistance. Thus, novel antibacterial agents and strategies to combat endometritis are needed. A total of 526 bacteria, including Staphylococcus spp. (26.3%), Streptococcus spp. (12.3%), E. coli (28.9%), Enterococcus spp. (20.1%), Proteus spp. (9.5%), and Corynebacterium spp. (2.8%), were isolated from sows with endometritis. We constructed a novel chimeric lysin, ClyL, which is composed of a cysteine- and histidine-dependent amidohydrolase/peptidase (CHAP) catalytic domain from the phage lysin LysGH15 and a cell wall-binding domain (CBD) from the prophage lysin Lys0859. The activities of ClyL and Lys0859 were most pronounced for the Staphylococcus and Streptococcus strains isolated from sow endometritis and bovine mastitis, respectively. ClyL and Lys0859 were combined to create a phage lysin cocktail, which demonstrated a synergistic effect against the coinfection of Staphylococcus and Streptococcus in vitro and in vivo. Furthermore, the combination of phage lysin cocktail and cefquinome had a synergistic bactericidal effect on boar semen that did not influence the activity of sperm. Remarkably, the incidence rate of sow endometritis was 0% (0/7) when the combination of phage lysin cocktail and cefquinome was used in semen via artificial insemination compared with 50% (3/6) when PBS was administered. Overall, the administration of a phage lysin cocktail and cefquinome in semen via artificial insemination is a promising novel strategy to prevent sow endometritis after artificial insemination.

Respiratory illnesses present a significant threat to porcine health, with co-infections involving Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Streptococcus suis (SS), Porcine Circovirus Type 2 (PCV2), and Porcine Circovirus Type 3 (PCV3) acting as the primary causative agents. As a result, the precise diagnosis of PRRSV, PCV2, PCV3 and SS is of paramount importance in the prevention and control of respiratory diseases in swine. Therefore, we conducted a molecular bioinformatical analysis to concurrently detect and differentiate PRRSV, PCV2, PCV3 and SS. We selected the ORF6 gene of PRRSV, the ORF2 gene of PCV2 and PCV3, and the glutamate dehydrogenase (GDH) gene of SS as targets. Specific primers and probes were designed for each pathogen, and following meticulous optimization of reaction conditions, we established a multiple TaqMan fluorescence quantitative PCR detection method. Subsequently, we subjected this method to a comprehensive assessment, evaluating its specificity, sensitivity, and repeatability. The research results demonstrated that the established multiple TaqMan fluorescence quantitative PCR detection method displays displayed exemplary specificity, with no instances of cross-reactivity with other pathogens. The method’s minimum detection concentrations for PRRSV, PCV2, PCV3, and SS were 2.80 × 101 copies/µL, 1.96 × 102 copies/µL, 2.30 × 102 copies/µL, and 1.75 × 103 copies/µL, respectively. When applied to the analysis of 30 clinical samples, the results closely mirrored those obtained through Chinese standard uniplex real-time qPCR detection method for PRRSV, as well as the general PCR methods for SS, PCV2, and PCV3. This study underscores the robust specificity, high sensitivity, and consistent stability of the multiple TaqMan fluorescence quantitative PCR detection method that we have developed. It is ideally suited to the clinical monitoring of PRRSV, PCV2, PCV3, and SS, and it carries significant importance in ongoing efforts to prevent and manage respiratory diseases in porcine populations.

Porcine rotavirus is a significant pathogen that causes rotavirus sickness in both humans and animals. G9 rotavirus, in particular, is thought to be a new rotavirus that has lately spread over the world between humans and pigs. However, the understanding of the pathogenicity of G9 rotavirus is limited to date. In the current study, a G9 porcine rotavirus strain was isolated in the fecal samples of diarrheal piglets from a large-scale pig farm located in Guangxi, China. Then, the virus was identified by western blotting, and the production dynamics of the virus were confirmed by an indirect immunofluorescence test with a viral titer of 107.46 TCID50/mL. Based on the VP7, VP4 and VP6 genes, phylogenetic analysis and sequencing data indicated that the GX9579 strain was of genotype G9P [23]I5. In addition, to explore the pathogenicity of the isolated GX9579 strain, animal tests were performed herein. Fecal viral shedding was detected, and fecal excretion was the highest at 105 copies/mu L 24h after the challenge and then gradually decreased. Histopathological test results suggested the intestinal villous arrangement of infected piglets became shortened, partially shed, and broken, intestinal villous epithelial cells shed into the intestinal lumen, and the villi propria lamina became hyperemic with severe bleeding and submucosal edema. Positive signals were seen throughout the intestinal villi's epithelial cells and the small intestine glands, according to immunohistochemical studies. These results provide reference data for further studies on the epidemiology and pathogenesis of G9 swine rotavirus.

Porcine viral diarrhea is a common ailment in clinical settings, causing significant economic losses to the swine industry. Notable culprits behind porcine viral diarrhea encompass transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), and porcine rotavirus-A (PoRVA). Co-infections involving the viruses are a common occurrence in clinical settings, thereby amplifying the complexities associated with differential diagnosis. As a consequence, it is therefore necessary to develop a method that can detect and differentiate all four porcine diarrhea viruses (TGEV, PEDV, PDCoV, and PoRVA) with a high sensitivity and specificity. Presently, polymerase chain reaction (PCR) is the go-to method for pathogen detection. In comparison to conventional PCR, TaqMan real-time PCR offers heightened sensitivity, superior specificity, and enhanced accuracy. This study aimed to develop a quadruplex real-time RT-qPCR assay, utilizing TaqMan probes, for the distinctive detection of TGEV, PEDV, PDCoV, and PoRVA. The quadruplex real-time RT-qPCR assay, as devised in this study, exhibited the capacity to avoid the detection of unrelated pathogens and demonstrated commendable specificity, sensitivity, repeatability, and reproducibility, boasting a limit of detection (LOD) of 27 copies/μL. In a comparative analysis involving 5483 clinical samples, the results from the commercial RT-qPCR kit and the quadruplex RT-qPCR for TGEV, PEDV, PDCoV, and PoRVA detection were entirely consistent. Following sample collection from October to March in Guangxi Zhuang Autonomous Region, we assessed the prevalence of TGEV, PEDV, PDCoV, and PoRVA in piglet diarrhea samples, revealing positive detection rates of 0.2% (11/5483), 8.82% (485/5483), 1.22% (67/5483), and 4.94% (271/5483), respectively. The co-infection rates of PEDV/PoRVA, PEDV/PDCoV, TGEV/PED/PoRVA, and PDCoV/PoRVA were 0.39%, 0.11%, 0.01%, and 0.03%, respectively, with no detection of other co-infections, as determined by the quadruplex real-time RT-qPCR. This research not only established a valuable tool for the simultaneous differentiation of TGEV, PEDV, PDCoV, and PoRVA in practical applications but also provided crucial insights into the prevalence of these viral pathogens causing diarrhea in Guangxi.

The porcine reproductive and respiratory syndrome virus (PRRSV) has caused significant economic losses to the swine industry. The U.S., China, and Peru have reported NADC30-like or NADC34-like PRRSV-infected piglets, which have been identified as the cause of a significant number of abortions in clinics. Although the pathogenicity of NADC30-like PRRSV and NADC34-like PRRSV in piglets exhibits significant variability globally, studies on their pathogenicity in China are limited. In this study, the animal experiments showed that within 8–14 days post-infection, both piglets infected with NADC30-like PRRSV GXGG-8011 and those infected with NADC34-like PRRSV LNSY-GY exhibited significant weight loss compared to the control piglets. Additionally, the viremia of the LNSY-GY persisted for 28 days, while the viremia of piglets infected with the GXGG-8011 lasted for 17 days. Similarly, the duration of viral shedding through the fecal–oral route after the LNSY-GY infection was longer than that observed after the GXGG-8011 infection. Furthermore, post-infection, both the LNSY-GY and GXGG-8011 led to pronounced histopathological lesions in the lungs of piglets, including interstitial pneumonia and notable viral colonization. However, the antibody production in the LNSY-GY-infected group occurred earlier than that in the GXGG-8011-infected group. Our research findings indicate that LNSY-GY is a mildly pathogenic strain in piglets, whereas we speculate that the GXGG-8011 might be a highly pathogenic strain.

Both porcine circovirus (PCV) and porcine parvovirus (PPV) cause various diseases and bring huge economic losses to the global swine industry. PCV2 is associated with several diseases and syndromes, including postweaning multisystemic wasting syndrome (PMWS), porcine dermatitis and nephropathy syndrome (PDNS) and porcine respiratory disease complex (PRDC). The classical PPV is one of the most common causes of reproductive failure in pigs. In this study, tissue samples (tonsil, lung, mesenteric lymph node, hilar lymph node and superficial inguinal lymph node) were collected from pigs with suspected PCV2-associated disease (PCVAD), and viral DNA was extracted. The coinfection of PCV2 and PPV1–5 was detected using the polymerase chain reaction (PCR) method. Phylogenetic analysis based on capsid genes of PCV2, PPV2, PPV3 and PPV5 was conducted. The prevalence rates of PCV2, PPV1, PPV2, PPV3, PPV4 and PPV5 were 51.2%, 15.9%, 36.6%, 19.5%, 14.6% and 10.9% on the individual pig level, respectively. The coinfection rates of PCV2 with PPV1, PPV2, PPV3, PPV4 and PPV5 were 8.5%, 25.6%, 17.1%, 13.4% and 3.7%, respectively. The prevalence of PPV2, PPV3 and PPV4 in PCV2-positive pigs was significantly higher than those in PCV2-negative pigs. Phylogenetic analyses were performed using the neighbor-joining (NJ) method with 1000 bootstraps. The results indicated the existence of PCV2d and two major clusters of PPV2, PPV3 and PPV5 in the Guangxi Autonomous Region. PCV2d was the dominant strain, and the novel PPVs were circulating in domestic pigs in the Guangxi Autonomous Region. The results of this study underline the importance of active surveillance of PCV2d and PPVs from the swine population in this area.

Salmonella and pathogenic Escherichia coli are important foodborne pathogens. Phages are being recognized as potential antibacterial agents to control foodborne pathogens. In the current study, a polyvalent broad-spectrum phage, GSP044, was isolated from pig farm sewage. It can simultaneously lyse many different serotypes of Salmonella and E. coli, exhibiting a broad host range. Using S. Enteritidis SE006 as the host bacterium, phage GSP044 was further characterized. GSP044 has a short latent period (10 min), high stability at different tem-peratures and pH, and good tolerance to chloroform. Genome sequencing analysis revealed that GSP044 has a double-stranded DNA (dsDNA) genome consisting of 110,563 bp with G + C content of 39%, and phylogenetic analysis of the terminase large subunit confirmed that GSP044 belonged to the Demerecviridae family, Epsepti-mavirus genus. In addition, the genomic sequence did not contain any lysogenicity-related, virulence-related, or antibiotic resistance-related genes. Analysis of phage-targeted host receptors revealed that the outer membrane protein (OMP) BtuB was identified as a required receptor for phage infection of host bacteria. The initial application capability of phage GSP044 was assessed using S. Enteritidis SE006. Phage GSP044 could effectively reduce biofilm formation and degrade the mature biofilm in vitro. Moreover, GSP044 significantly decreased the viable counts of artificially contaminated S. Enteritidis in chicken feed and drinking water. In vivo tests, a mouse model of intestinal infection demonstrated that phage GSP044 was able to reduce the number of colonized S. Enteritidis in the intestine. These results suggest that phage GSP044 may be a promising candidate biologic agent for controlling Salmonella infections.

Senecavirus A (SVA), an emerging infectious disease, is associated with the porcine idiopathic vesicular disease. Here, the pathogenesis of different strains of SVA was investigated in growing-finishing pigs. We aimed to evaluate the replication characteristics, virus particle morphology, clinical signs, and vesicular lesions in comparison with two different strains of SVA. The animals were infected with SVA HB-CH-2016 or CH/AH-02/2017 by intranasal routes (3 mL, 109TCID50 /mL) and monitored daily for 14 days post-inoculation (dpi) for clinical signs and vesicular lesions. Viremia or viral shedding was detected in the blood, fecal swab, and nasal swab samples. Results showed no distinct differences in plaque size, replication ability, and characteristic virions between SVA HB-CH-2016 and CH/AH-02/2017 strains. Animal experimental results showed that both SVA CH/AH-02/2017 and SVA HB-CH-2016 could infect pigs. However, an obvious difference in the pathogenicity and dynamics of infection was observed between SVA HB-CH-2016 and CH/AH-02/2017 strains. The pathogenesis of SVA CH/AH-02/2017 was similar to that of published results of USA strains, whereas the SVA HB-CH-2016 strain had low pathogenicity to pigs. Clinical signs and vesicular lesions were observed in SVA CH/AH-02/2017-infected pigs. Additionally, the different branches of SVA should be capable of inducing broad cross-reactive neutralizing antibodies, which play an important role in clearing the SVA virus. This study of animal models for SVA infection will be beneficial to develop vaccines and antivirals.

为探究生产母猪心力衰竭(heart failure)的病理变化和组织学特征,对广西某规模化猪场45头死亡生产母猪进行了临床症状观察、大体解剖和组织病理学检查.结果,其中18头病猪临床症状表现为易疲劳,精神沉郁,呼吸困难,夜间咳嗽和突然死亡;剖检可见心包严重黏连或心室扩张、心包积液、心肌出血、心脏横径与纵径之比增大,以及肝、脾、肺、肾的淤血肿胀;组织病理学变化表现为心肌肿胀变性或萎缩坏死,纤维素性肺炎、间质性肺炎、化脓性肺炎和支气管肺炎,以及多个器官的淤血.结果 表明,心力衰竭为母猪突然死亡的重要原因,其主要病理学特征为心室扩张或心包粘连,心肌肿胀坏死、心肌纤维化并伴随多器官淤血病变.

为了研究广西贵港地区猪伪狂犬病区域净化防控效果,2019年5-11月对广西贵港地区部分规模化猪场采集血液样品2 863份,猪场环境拭子、车拭子、工作人员手拭子共1 600份,猪精子372份,并于猪场内及外围捕捉野生鼠78只,采集脑、扁桃体等病料,用PCR、荧光定量PCR和ELISA分别进行病原学和血清学检测.结果显示:病原学检测均为阴性;血清学gE抗体ELISA检测均为阴性;血清学gB抗体ELISA检测平均阳性率为87.18％,其中种公猪阳性率为93.82％,生产母猪阳性率为99.57％,后备猪阳性率为98.40％,育肥猪为60.14％.结果表明,广西贵港地区猪伪狂犬病区域净化效果显著.

Porcine epidemic diarrhea (PED) has re-emerged in recent years and has already caused huge economic losses to the porcine industry all over the world. Therefore, it is urgent for us to find out efficient ways to prevent and control this disease. In this study, the antiviral activity of a cationic amphibian antimicrobial peptide Caerin1.1 against porcine epidemic diarrhea virus (PEDV) was evaluated by an in vitro system using Vero cells. We found that even at a very low concentration, Caerin1.1 has the ability to destroy the integrity of the virus particles to block the release of the viruses, resulting in a considerable decrease in PEDV infections. In addition, Caerin1.1 showed powerful antiviral activity without interfering with the binding progress between PEDV and the receptor of the cells, therefore, it could be used as a potential antiviral drug or as a microbicide compound for prevention and control of PEDV.

The aims of the present study were to establish optimal doses and provide an alternate COPD for florfenicol against Streptococcus suis based on pharmacokinetic-pharmacodynamic integration modeling. The recommended dose (30 mg/kg b.w.) were administered in healthy pigs through intramuscular and intravenous routes for pharmacokinetic studies. The main pharmacokinetic parameters of Cmax, AUC0-24h, AUC, Ke, t1/2ke, MRT, Tmax, and Clb, were estimated as 4.44 μg/ml, 88.85 μg⋅h/ml, 158.56 μg⋅h/ml, 0.048 h-1, 14.46 h, 26.11 h, 4 h and 0.185 L/h⋅kg, respectively. The bioavailability of florfenicol was calculated to be 99.14% after I.M administration. A total of 124 Streptococcus suis from most cities of China were isolated to determine the minimum inhibitory concentration (MIC) of florfenicol. The MIC50 and MIC90 were calculated as 1 and 2 μg/ml. A serotype 2 Streptococcus suis (WH-2), with MIC value similar to MIC90, was selected as a representative for an in vitro and ex vivo pharmacodynamics study. The MIC values of WH-2 in TSB and plasma were 2 μg/ml, and the MBC/MIC ratios were 2 in TSB and plasma. The MPC was detected to be 3.2 μg/ml. According to inhibitory sigmoid Emax model, plasma AUC0-24h/MIC values of florfenicol versus Streptococcus suis were 37.89, 44.02, and 46.42 h for the bactericidal, bacteriostatic, and elimination activity, respectively. Monte Carlo simulations the optimal doses for bactericidal, bacteriostatic, and elimination effects were calculated as 16.5, 19.17, and 20.14 mg/kg b.w. for 50% target attainment rates (TAR), and 21.55, 25.02, and 26.85 mg/kg b.w. for 90% TAR, respectively. The PK-PD cutoff value (COPD) analyzed from MCS for florfenicol against Streptococcus suis was 1 μg/ml which could provide a sensitivity cutoff value. These results contributed an optimized alternative to clinical veterinary medicine and showed that the dose of 25.02 mg/kg florfenicol for 24 h could have a bactericidal action against Streptococcus suis after I.M administration. However, it should be validated in clinical practice in the future investigations.

The aim of this study was to explore the bioequivalence of long-acting oxytetracycline in two formulations, a reference formulation (Terramycin 20% LA, Pfizer) and a test one (Kangtekang 20% LA, Huishen). Both formulations were administered intramuscularly at 20 mg/kg body weight at each of 24 healthy animals during a two-period crossover parallel experimental design. The oxytetracycline (OTC) concentrations in plasma were measured by high-performance liquid chromatography, and the limit of quantification was 0.05 mu g/ml with a recovery ratio of above 90%. Moreover, the descriptive pharmacokinetics parameters (C-max, AUC(0-144h), and AUG(0-infinity)) were calculated and compared under analysis of variance, and 90% confidence interval (CI) were compared, except for T-max analyzed by non-parametric tests based on Wilcoxons's signed rank test. The comparison results of C-max, AUC(0-144h), AUC(0-infinity), and T-max were 5.066 +/- 0.486, 5.071 +/- 0.877 mu g/ml, 118.926 +/- 13.259, 126.179 +/- 17.390 mu g h/ml, 123.087 +/- 13.906, 130.732 +/- 18.562 mu g h/ml, 0.740 +/- 0.278, 0.650 +/- 0.258 h, respectively, and did not reveal any significant differences. In addition, 90% Cls of these ratios for reference and test product were within an interval of 80-125%, and the relative bioavailability of test one was (94.291 +/- 15.287)%. Therefore, it has been concluded that test OTC was bioequivalent to the reference formulation in pigs.

A new, more palatable formulation of 10% enrofloxacin enteric-coated granules was investigated to evaluate the pharmacokinetic effect in plasma, the residue elimination in tissues and the clinical efficacy against Actinobacillus pleuropneumonia (APP) and Mycoplasam suis (MS) in pigs. In this study, the enrofloxacin concentrations in plasma and tissues were detected using high-performance liquid chromatography with phosphate buffer (pH = 3) and acetonitrile. The pharmacokinetics and elimination of enrofloxacin enteric-coated granules were performed after oral administration at a single dose of 10 mg/kg body weight (bw) and 5 mg/kg twice per day for 5 consecutive days, respectively. The in vivo antibacterial efficacy and clinical effectiveness of enrofloxacin enteric-coated granules against APP and MS were assayed at 2.5, 5, 10 mg/kg, compared with tiamulin (8 mg/kg) based on establishment of APP and MS infection models. 56 APP strains were selected and tested for in vitro antibacterial activity of enrofloxacin enteric-coated granules. The main parameters of elimination half-life (t1/2β), Tmax, and area under the curve (AUC) were 14.99 ± 4.19, 3.99 ± 0.10, and 38.93 ± 1.52 μg h/ml, respectively, revealing that the enrofloxacin concentration remained high and with a sustainable distribution in plasma. Moreover, the analysis on the evaluation of enrofloxacin and ciprofloxacin in muscle, fat, liver and kidney showed that the recovery were more than 84% recovery in accordance with the veterinary drug residue guidelines of United States pharmacopeia, and the withdrawal periods were 4.28, 3.81, 4.84, and 3.51 days, respectively, suggesting that the withdrawal period was 5 d after oral administration of 5 mg/kg twice per day. The optimal dosage of enrofloxacin enteric-coated granules against APP and MS was 5 mg/kg, with over 90% efficacy, which was significantly different (p < 0.05) to the 2.5 mg/kg group, but not to the 10 mg/kg group or the positive control group (tiamulin). In conclusion, 10% enrofloxacin enteric-coated granules had significant potential for treating APP and MS, and it provided an alternative enrofloxacin palatability formulation.

作为一种新型的教育模式,翻转课堂受到越来越多的关注.课题组通过具体的教学实践,对翻转课堂在兽医药理学中的应用进行探讨和分析研究.结果显示,翻转课堂模式对提高学生自主学习兴趣,增强师生交流与沟通具有重要意义,能让学生在轻松自由的环境中学习、掌握兽医药理学知识.

Haemophilus parasuis (H.parasuis) is the etiological agent of porcine polyserositis and arthritis (Glässer's disease) characterized by fibrinous polyserositis, meningitis and polyarthritis, causing severe economic losses to the swine industry. Currently, the molecular basis of this infection is largely unkonwn. Coronin 1A (Coro1A) plays important roles in host against bacterial infection, yet little is known about porcine Coro1A. In this study, we investigated the molecular characterization of porcine Coro1A, revealing that porcine Coro1A was widely expressed in different tissues. Coro1A could be induced by lipopolysaccharide (LPS), polyinosinic acid-polycytidylic acid [poly (I:C)] and H.parasuis in porcine kidney-15 (PK-15) cells. Functional analyses revealed that porcine Coro1A suppressed the NF-κB activation during H.parasuis infection by inhibiting the degradation of IκBα and nuclear translocation of p65. Overexpression of porcine Coro1A inhibited the transcription of NF-κB-mediated downstream genes [Interleukin-6 (IL-6), Interleukin-8 (IL-8) and COX-2] through down-regulation of NF-κB. The results indicated that porcine Coro1A is an important immunity related gene that helps to inhibit NF-kB activation during H. parasuis infection.

Synthetically designed antimicrobial peptides (AMPs) present the potential of replacing antibiotics in the treatment of bacterial infections. However, microbial resistance to AMPs has been reported and little is known regarding the underlying mechanism of such resistance. The naturally occurring AMP cecropin B (CB) disrupts the anionic cell membranes of Gram-negative bacteria. In this study, CB resistance (CBR) was induced in Haemophilusparasuis SH0165 by exposing it to a series of CB concentrations. The CB-resistant H.parasuis strains CBR30 and CBR30-50 were obtained. The growth curves of SH0165 and CBR30 showed that CBR30 displayed lower growth rates than SH0165. The result of transmission electron microscopy showed cell membranes of the CB-resistant CBR30 and CBR30-50 were smoother than SH0165. Microarrays detected 257 upregulated and 254 downregulated genes covering 20 clusters of orthologous groups (COGs) of the CB-resistant CBR30 compared with SH0165 (>1.5-fold change, p < 0.05). Sixty genes were affected in CBR30-50 covering 18 COGs, with 28 upregulated and 32 downregulated genes. Under the COG function classification, the majority of affected genes in the CB-resistant CBR30 and CBR30-50 belong to the category of inorganic ion transport, amino acid transport, and metabolism. The microarray results were validated by real-time quantitative reverse transcription PCR. This study may provide useful guidance for understanding the molecular mechanism underlying H.parasuis resistance to CB.

Objective To learn the distribution and drug-resistance trend of pathogenic bacteria in our hospital,in order to provide basis for correct use of clinical antimicrobial agents.Methods Between January 2011 and January 2012,we performed bacterial culture and drug sensitivity test for 1643 clinical specimens coming from both outpatients and inpatients,and analyzed drug resistance of the bacteria.Results Among the 1 643 bacterial culture specimens,we found a total of 750 strains of pathogenic bacteria,indicating a positive rate of 45.6%.Among the pathogenic bacteria,there were 242 strains of G+ cocci,occupying 32.3% with a majority of staphylococcus aureus,coagulase negative staphylococcus and enterococcus genera;there were 382 strains of G-bacilli,occupying 50.9% with a majority of escherichia coli,pseudomonas aeruginosa,klebsiella pneumoniae,enterobacter and acinetobacter baumannii.Methicillin resistant staphylococcus aureus(MRSA) accounted for 59.0% of staphylococcus aureus.And the drug resistance rate of staphylococcus aureus to penicillin and cefazolin were both 100.0%.Among the enterococcus,dung enterococcus and shit enterococcus were of the highest separation rate.The drug resistance rate of dung enterococcus to penicillin was 35.3%.The detection rates of escherichia coli and klebsiella pneumoniae producing ESBL(Extended-spectrum beta-lactamase) were 77.6% and 56.7% respectively;non-fermentative bacteria consisted mainly of pseudomonas aeruginosa and baumanii,and the separation rate of olefinic kind of acinetobacter baumannii resisting carbon blue mould from acinetobacter baumannii was 37%.The drug resistance rates of acinetobacter baumannii and pseudomonas aeruginosa to imipenem were 46.3% and 28.3% respectively.Conclusions In our hospital,the bacterial drug resistance is high.Reasonable application of antimicrobial agents should be strengthened;the use of the third generation cephalosporins and other beta lactam kind of antibacterial drugs should be careful in order to reduce antibiotic selective pressure to prevent drug-resistant strains within the hospital.