Nanoparticles for the Treatment of Oral Biofilms: Current State, Mechanisms, Influencing Factors, and Prospects.

Due to their excellent size, designability, and outstanding targeted antibacterial effects, nanoparticles have become a potential option for controlling oral biofilm-related infections. However, the formation of an oral biofilm is a dynamic process, and factors affecting the performance of antibiofilm treatments are complex. As such, when examining the existing literature on the antibiofilm effects of nanoparticles, attention should be paid to the specific mechanisms of action at different stages of oral biofilm formation, as well as relevant influencing factors, in order to achieve an objective and comprehensive evaluation. This review is intended to detail the antibacterial mechanisms of nanoparticles during the four stages of the formation of oral biofilms: 1) acquired film formation; 2) bacterial adhesion; 3) early biofilm development; and 4) biofilm maturation. In addition, factors influencing the antibiofilm properties of nanoparticles are summarized from the aspects of nanoparticles themselves, biofilm models, and host factors. The limitations of current research and possible trends for future research are also discussed. In summary, nanoparticles are a promising antioral biofilm strategy. It is hoped that this review can serve as a reference and inspire ideas for further research on the application of nanoparticles for effectively targeting and treating oral biofilms.

[Analysis of distribution, drug resistance and risk factors of pathogens isolated from septicemic patients].

OBJECTIVE: To investigate distribution, drug resistance and risk factors of pathogens isolated from septicemic patients in a hospital in the past 6 years. METHODS: Most of the bacterial isolates were identified with BD Phoenix, and a few isolates were identified manually and with K-B method. Candida isolates were identified with color display plates and K-B method. WHONET5.4 software was used for analysis. RESULTS: The common bacteria isolated form the blood included E. coli, P. aeruginosa, K. pneumoniae, and S. aureu. The gram-negative bacillus from the blood exhibited relatively low resistance to such antibiotics as cefoperazone/sulbactam, imipenem, amikacin, piperacillin/tazobactam, and ceftazidime, and the incidences of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) ranged between 33.3% and 34.9% and between 32.9% and 36.0%, respectively. The gram-positive coccus from blood showed a sensitivity rate of 100.0% to vancomycin and low resistant rates to amikacin and chloramphenicol; the methicillin-resistant rates of S. aureu and coagulase-negative staphylococcus were 26.9%-35.5% and 72.7%-74.3%, respectively. The risk factors of septicemia included hospital stay for over 5 days, venous catheterization, surgeries, puncture, oxygen therapy, urine tract catheterization, and chemotherapy. CONCLUSION: Blood culture can be of importance in patients with septicemia, and the use of antibiotics should be carefully weighed according to the results of bacterial culture and sensitivity tests of the pathogens isolated from the blood.

[ALL 98 strains of Brucella OMP25 gene is conservative in China].

OBJECTIVE: To investigate the genetic polymorphism of OMP25 gene isolated from 116 Brucella strains, including 18 Brucella reference strains and 98 Chinese field strains. METHODS: Chromosomal DNA of Brucella strains were analyzed by PCR, and then the product OMP25 gene was digested with Hind III and separated on 10% polypropylene agarose gel electrophoresis. OMP25 genes of different types were sequenced. RESULTS: Eight gene types (I-VIII) existing in 116 strains were examined, among them type II and VII were only found in certain wild strains. Sequencing analysis of OMP25 revealed only 10 sites varied in all 8 types. OMP25 of 98 Chinese Brucella strains was highly homologic and characteristic of stable antigen. CONCLUSION: High conservation characteristics helps to epidemiologically detect Brucella in China as well as to found a theoretical basis for vaccine development.

[Distribution and drug resistance spectrum analysis of 2478 clinical bacterial and Candida isolates].

OBJECTIVE: To investigate the distribution and drug resistance spectrum of clinical bacterial and Candida isolates. METHODS: Most of the bacterial isolates were identified using automated BD Phoenix, and a few with K-B method carried out manually. Candida isolates were identified by color-display plate and K-B method. RESULTS: The most common isolates in the 2478 strains were P. aeruginosa (15.6%), E. coli (11.5%), C. albicans (9.6%), K. pneumoniae (9.3%), S. aureu (8.2%), and S. epidermidis (7.5%). In gram-negative isolates, the antibiotics with the lowest resistance rate were meraopenem (14.4%), cefoperazone/Sulbactam (14.8%), Imipenem (21.9%), piperacillin/tazobactam (27.4%), ceftazidime (30.0%), amikacin (31.1%), and cefepime (33.1%). The detection rate of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) were 47.4% and 37.3% respectively. In gram-positive isolates, the antibiotics with the lowest resistance rate were vancomycin (0.9%), teicoplanin (1.1%), nitrofurantoin (6.9%), amikacin (20.1%), chloramphenicol (30.7%), and cefoperazone/sulbactam (31.5%). The methecillin-resistant rates of S. aureu , S. epidermidis, and S. haemolyticus were 57.1%, 65.0%, and 66.0%. For Candida isolates, the most sensitive antibiotics were amphotericin B (0.3%), nystain (0.3%), itraconazole (5.6%), fluconazole (9.4%), and fluorocytosine (9.4%). CONCLUSION: The results suggest high rate of ESBL production and oxacillin resistance of the bacteria isolated in the hospital. More rational use of antimicrobial agents is crucial for reducing the drug-resistance of the bacteria, and effective measures must be taken to reduce dissemination of multidrug-resistant bacteria.

[Sequence analysis of housekeeping genes recA, dnaE, and mdh in different serogroups or biotypes of Vibrio cholerae isolated from China].

OBJECTIVE: To analyze sequences of the housekeeping genes including recA, dnaE, and mdh in different serogroups or different biotypes of Vibrio cholerae (VC) strains isolated from China. METHODS AND RESULTS: recA, dnaE, and mdh genes of Vibrio cholerae were obtained by PCR, sequenced and analyzed. Forty-four variable bases were identified in the 500 bases of recA gene of 18 VC strains, and the mutation of only 3 variable bases could result in changes of 2 amino acids. In the 600 bases of dnaE genes of 18 strains, 32 variable bases were found and only 1 contributed to an amino acid change. In the 367 bases of mdh genes of 18 strains, only 1 variable base was identified whose mutation involved an amino acid convertion. Toxic EI Tor biotype (EVC) strains and toxic O139 serogroup strains were closely related. Non-toxic strains of different serogroups or types were lowly related. Non-toxic and toxic strains of different serogroups or types were lowly related. CONCLUSION: Toxic EVC and toxic O139 serogroup strains isolated from different areas of China may evolve from a common original strain, and toxic O139 VC strains may come from toxic EVC strains.

[Analysis of drug resistance spectrum and its mechanism in 1017 clinical bacterial isolates].

OBJECTIVE: To investigate the drug susceptibility of the clinical bacterial isolates to provide evidence for more adequate use of antibiotics. METHODS: Altogether 1017 clinical bacterial isolates were identified by BD Phoenix and tested for resistance against antimicrobial agents by K-B method. WHONET5 was applied for the analysis. RESULTS: The most frequent bacteria detected included P. aeruginosa (19.37%), coagulase-negative Staphylococci (CNS, 17.70%), E. coli (13.27%), S. aureu (SA, 12.09%), E. faecalis (11.8%), and K. pneumoniae (7.57%). In gram-negative isolates, the susceptibility rate of imipenem was 81.5%, and that of ceftazidime was above 70%. The incidences of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) were 34.8% and 45.5% respectively. In gram-positive isolates, the susceptibility rates of vancomycin and Teicoplanin were 98.8% and 100.0% respectively, and those of furazolidone, imipenem, amikacin, piperacillin/ tazobactam were above 70%. The oxacillin resistant rates of CNS and SA were 78.2% and 46.8%. CONCLUSION: The 1017 clinical bacterial isolates are characterized by high ratio of ESBL production and oxacillin resistance, suggesting the importance of adequate use of antimicrobial agents and effective control measures for reducing the drug resistance and preventing the spread of multi drug- resistant bacteria.

[A field trial for evaluating the safety of recombinant human interferon alpha-2b for nasal spray].

OBJECTIVE: To evaluate the safety of recombinant human interferon alpha-2b for nasal spray for the prevention of SARS and other upper respiratory viral infections. METHODS: Field epidemiologic evaluation was conducted, the design was randomized and had a synchronously parallel control group. In the study, the drugs were given for five days and all subjects were followed up for ten days. RESULTS: During the period of using interferon, body temperature of the experimental group was normal compared to the control group. Experimental group had more influenza-like symptoms than the control group (P < 0.05), such as headache (4.83%-7.09%), dizziness (7.17%-11.63%), lassitude (8.55%-15.06%), muscular soreness (4.43%-7.09%), pharynx dryness (12.10%-17.85%), angina (6.25%-8.72%), abdominal pain (2.30%-5.50%) and diarrhea (2.45%-5.66%). Most of side effects reached their peak with in the first 3 days. Except for pharynx dryness, the incidences of all other side effects declined after completion of the use of the trial drug, and incidences of some symptoms in experimental group were lower than those of the control group. There were no significant differences in the symptoms of cough and expectoration between the experimental group and the control group. The incidence of exanthem in the control group was significantly higher than that in the experimental group. The side effect of bloody nasal mucus was not observed in experimental group, which had been reported by other authors in several volunteer studies. CONCLUSION: Using recombinant human interferon alpha-2b for nasal spray could lead to some influenza-like symptoms, however, all those symptoms were mild , reversible, and relieved after completion of the use of the trial drug. No serious side effects were found during the period of following up. The authors conclude that the drug is safe.

[Sequence analysis of the mutated genes in CTXEVC Phi and nct-CTXnew Phi genomes in Vibrio cholerae JS94484 strain].

OBJECTIVE: To analyze the sequences of the mutated genes in CTX(EVC)Phi and nct-CTX(new)Phi genomes in Vibrio cholerae JS94484 strain. METHODS: The mutated genes in CTX(EVC)Phi and nct-CTX(new)Phi genome were obtained by PCR, sequenced and analyzed. RESULTS: ig1, rstR, ig2, and ctxAB genes in CTX(EVC)Phi genome of V. cholerae strain JS94484 were highly homologous with those of standard EVC strain N16961, while ig1, rstR and ig2 genes in nct-CTX(new)Phi genome of the strain JS94484 shared low homology with those of the other 3 biotypes of V. cholerae. Considerable difference was detected in the last 60 bp of zot genes between CTX(EVC)Phi and nct-CTX(new)Phi genomes, indicating possible difference in the amino sequences of the Zot proteins encoded by these two genes. The sequence of toxin-coregulated pilus A subunit gene (tcpA) of the strain JS94484 was identical with that of strain N16961. CONCLUSION: ig1, rstR and ig2 genes of nct-CTX(new)Phigenome are of a novel type, and their functions await further investigation.

Acute diarrhea during army field exercise in southern China.

AIM: During emergency period, infectious diseases can be a major threat to military forces. During field training in southern China, diarrhea is the main cause of nonbattle injury. To evaluate the causes of and risk factors for diarrhea in emergency period, we collected clinical and epidemiological data from the People's Liberation Army (PLA) during field training in southern China. METHODS: From September 25 to October 2 1997, 2636 military personnel were investigated. Fecal sample cultures for lapactic pathogens were obtained from 103 military personnel with diarrhea. In addition, a questionnaire was administered to 103 cases and 206 controls to evaluate the association between illness and potential risk factors. At the same time, another questionnaire of 1:4 case-case control was administered to 22 severe cases (each severe case paired 4 mild cases). RESULTS: The training troop's diarrhea incidence rate was significantly higher than that of garrison. The diarrhea incidence rate of officers was significantly lower than that of soldiers. A lapactic pathogen was identified in 63.1% (65/103) of the troops with diarrhea. Enterotoxigenic Escherichia coli (35.0%) and plesiomona shigelloides (16.5%) were the most common bacterial pathogens. All bacterial isolates were sensitive to norfloxacin and ceftazidine. However, almost all of them were resistant to sulfamethoxazole, trimethoprim-sulfamethoxazole, oxytetracycline, doxycycline, furazolidone, ampicillin and cloromycetin to a different degree. Risk factors associated with diarrhea included drinking raw water, eating outside, contacting diarrhea patients, lacking sanitation, depression, lacking sleep, which were established by multiple-factor logistic regression analysis. In addition, the unit incidence rate was associated with the density of flies and the average daily boiled water available by regression and discriminate analysis. CONCLUSION: A series of risk factors are associated with the incidence rate of diarrhea. Our results may provide a useful basis for prevention and cure of diarrhea in emergency period of PLA.