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Antimicrobial resistance poses a significant threat to public health and social development worldwide. This study aimed to investigate the effectiveness of silver nanoparticles (AgNPs) in treating multidrug-resistant bacterial infections. Eco-friendly spherical AgNPs were synthesized using rutin at room temperature. The biocompatibility of both polyvinyl pyrrolidone (PVP) and mouse serum (MS)-stabilized AgNPs was evaluated at 20 μg/mL and showed a similar distribution in mice. However, only MS-AgNPs significantly protected mice from sepsis caused by the multidrug-resistant Escherichia coli (E. coli) CQ10 strain (p = 0.039). The data revealed that MS-AgNPs facilitated the elimination of Escherichia coli (E. coli) in the blood and the spleen, and the mice experienced only a mild inflammatory response, as interleukin-6, tumor necrosis factor-α, chemokine KC, and C-reactive protein levels were significantly lower than those in the control group. The results suggest that the plasma protein corona strengthens the antibacterial effect of AgNPs in vivo and may be a potential strategy for combating antimicrobial resistance.

It was assumed that dietary inclusion of Lactobacillus reuteri SL001 isolated from the gastric contents of rabbits could act as an alternative to feed antibiotics to improve the growth performance of broiler chickens. We randomly assigned 360 one-day-old AA white-feathered chicks in three treatments: basal diet (control), basal diet plus zinc bacitracin (antibiotic), and basal diet plus L. reuteri SL001 (SL001) treatment. The results showed the total BW gain and average daily gain (ADG) of broilers in SL001 treatment increased significantly (p < 0.05, respectively) compared with the control group from day 0 to 42. Moreover, we observed higher levels of immune globulins in both the SL001 group and the antibiotic group. Total antioxidant capacity and levels of antioxidant factors were also significantly increased (p ≤ 0.05, respectively) in the SL001 treatment group, while the interleukin 6, interleukin 4, creatinine, uric acid, total cholesterol, triglyceride, VLDL, LDL and malondialdehyde were remarkably decreased (p < 0.05, respectively). In the ileum of SL001 treatment broilers, the height of villi and the ratio of villi height to crypt depth were significantly increased (p < 0.05). Meanwhile, the crypt depth reduced (p < 0.01) and the ratio of villi height to crypt depth increased (p < 0.05) in the jejunum compared to the control. The abundance of microbiota increased in the gut of broilers supplemented with SL001. Dietary SL001 significantly increased the relative abundance of Actinobacteria in the cecal contents of broilers (p < 0.01) at the phylum level. In conclusion, L. reuteri SL001 supplementation promotes the growth performance of broiler chickens and exhibits the potential application value in the industry of broiler feeding.

The emerging and spreading of multi-drug resistant (MDR) bacteria have been becoming one of the most severe threats to human health. Enhancing oxidative stress as mimicking immune system was considered as a potential strategy to fight against infection of MDR bacteria. In this study, we investigated the antibacterial efficiency of such a strategy which combines silver nanoparticles (AgNPs) with ebselen. The results showed that AgNPs and ebselen combination had significant synergistic killing effects both on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in vitro, including model strains of China Veterinary Culture Collection and MDR clinical isolates, which is similar as the combination of silver ion and ebselen. AgNPs exhibited to be a strong inhibitor of bacterial thioredoxin reductase, same as a free silver ion. Ebselen mitigated the cytotoxicity of AgNPs to HeLa cells. However, in a bacteria-cell coexistence condition, the synergistic bactericidal effect was only observed on S. aureus (p

Streptococcus suis sequence type (ST) 7 has been spreading throughout China. To determine events associated with its emergence, we tested 114 isolates. In all 106 ST7 strains responsible for human outbreaks and sporadic infections, the tetracycline-resistance gene, tetM, was detected on the conjugative transposon Tn916. Horizontal transmission of tetM is suspected.

An outbreak of Streptococcus suis serotype 2 emerged in the summer of 2005 in Sichuan Province, and sporadic infections occurred in 4 additional provinces of China. In total, 99 S. suis strains were isolated and analyzed in this study: 88 isolates from human patients and 11 from diseased pigs. We defined 98 of 99 isolates as pulse type I by using pulsed-field gel electrophoresis analysis of SmaI-digested chromosomal DNA. Furthermore, multilocus sequence typing classified 97 of 98 members of the pulse type I in the same sequence type (ST), ST-7. Isolates of ST-7 were more toxic to peripheral blood mononuclear cells than ST-1 strains. S. suis ST-7, the causative agent, was a single-locus variant of ST-1 with increased virulence. These findings strongly suggest that ST-7 is an emerging, highly virulent S. suis clone that caused the largest S. suis outbreak ever described.

Background Shiga toxin-producing Escherichia coli (STEC) is recognized as an important human diarrheal pathogen. Swine plays an important role as a carrier of this pathogen. In this study we determined the prevalence and characteristics of STEC from healthy swine collected between May 2011 and August 2012 from 3 cities/provinces in China. Results A total of 1003 samples, including 326 fecal, 351 small intestinal contents and 326 colon contents samples, was analyzed. Two hundred and fifty five samples were stx-positive by PCR and 93 STEC isolates were recovered from 62 stx-positive samples. Twelve O serogroups and 19 O:H serotypes including 6 serotypes (O100:H20/[H20], O143:H38/[H38], O87:H10, O172:H30/[H30], O159:H16, O9:H30/[H30]) rarely found in swine and ruminants were identified. All 93 STEC isolates harbored stx2 only, all of which were stx2e subtype including 1 isolate being a new variant of stx2e. 53.76%, 15.05% and 2.15% STEC isolates carried astA, hlyA and ehxA respectively. Four STEC isolates harbored the high-pathogenicity island. Of the 15 adherence-associated genes tested, 13 (eae, efa1, iha, lpfAO113, lpfAO157/OI- 154, lpfAO157/OI-141, toxB, saa, F4, F5, F6, F17 or F41) were all absent while 2 (paa and F18) were present in 7 and 4 STEC isolates respectively. The majority of the isolates were resistant to tetracycline (79.57%), nalidixic acid (78.49%), trimethoprim-sulfamethoxazole (73.12%) and kanamycin (55.91%). The STEC isolates were divided into 63 pulsed-field gel electrophoresis patterns and 21 sequence types (STs). Isolates of the same STs generally showed the same or similar drug resistance patterns. A higher proportion of STEC isolates from Chongqing showed multidrug resistance with one ST (ST3628) resistant to 14 antimicrobials. Conclusions Our results indicate that swine is a significant reservoir of STEC strains in China. Based on comparison by serotypes and sequence types with human strains and presence of virulence genes, the swine STEC may have a low potential to cause human disease. [ABSTRACT FROM AUTHOR]

Cholesterol-dependent cytolysins (CDC) are pore forming toxins. A prototype of the CDC family members is perfringolysin O (PFO), which directly binds to the cell membrane enriched in cholesterol, causing cell lysis. However, an exception of this general observation is intermedilysin (ILY) of Streptococcus intermedius, which requires human CD59 as a receptor in addition to cholesterol for its hemolytic activity. A possible explanation of this functional difference is the conformational variation between the C-terminal domains of the two toxins, particularly in the highly conserved undecapeptide termed tryptophan rich motif. Here, we present the crystal structure of suilysin, a CDC toxin from the infectious swine pathogen Streptococcus suis. Like PFO, suilysin does not require a host receptor for hemolytic activity; yet the crystal structure of suilysin exhibits a similar conformation in the tryptophan rich motif to ILY. This observation suggests that the current view of the structure-function relationship between CDC proteins and membrane association is far from complete. [ABSTRACT FROM AUTHOR]

Background. Streptococcus suis emerged to cause an unusual outbreak of streptococcal toxic-shock-like syndrome (STSLS) in 2005. The mechanisms involved are unknown. Methods. Clinical, laboratory, and epidemiologic data on patients infected with culture-confirmed S. suis were analyzed. The strain involved in the outbreak, "epidemic" strain ST7, was compared with both a classical highly pathogenic strain, ST1, and an intermediately pathogenic strain, ST25, to determine both its capacity to induce cytokines in experimentally infected mice and its genomic difference. Results. Of 38 patients infected with culture-confirmed S. suis, 14 presented with STSLS. During the early phase of the disease, serum levels of interleukin (IL)-1β, IL-6, IL-8, IL-12p70, interferon-γ, and tumor necrosis factor-α were more elevated in patients with STSLS than in those with meningitis only. Serum levels of proinflammatory cytokines were significantly higher in mice infected with ST7 than in those infected with either ST1 or ST25. Genomic comparisons with ST25 showed that ST1 had acquired 132 genomic islands, including 5 pathogenicity islands, and that ST7, the epidemic strain, had acquired an additional 5 genomic islands. Conclusion. Intermediately pathogenic strain ST25 has evolved to become highly pathogenic strain ST1, which, in turn, has more recently evolved to become epidemic strain ST7. ST7 has the ability to stimulate the production of massive amounts of proinflammatory cytokines, leading to STSLS. [ABSTRACT FROM AUTHOR]