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Acinetobacter baumannii has been listed as one of the most critical pathogens in nosocomial infections; however, the key genes and mechanisms to adapt to the host microenvironment lack in-depth understanding. In this study, a total of 76 isolates (from 8 to 12 isolates per patient, spanning 128 to 188 days) were longitudinally collected from eight patients to investigate the within-host evolution of A. baumannii. A total of 70 within-host mutations were identified, 80% of which were nonsynonymous, indicating the important role of positive selection. Several evolutionary strategies of A. baumannii to increase its potential to adapt to the host microenvironment were identified, including hypermutation and recombination. Six genes were mutated in isolates from two or more patients, including two TonB-dependent receptor genes (bauA and BJAB07104_RS00665). In particular, the siderophore receptor gene bauA was mutated in multiple isolates from four patients with three MLST types, and all mutations were at amino acid 391 in ligand-binding sites. With 391T or 391A, BauA was more strongly bound to siderophores, which promoted the iron-absorption activity of A. baumannii at acidic or neutral pH, respectively. Through the A/T mutation at site 391 of BauA, A. baumannii displayed two reversible phases to adapt to distinct pH microenvironments. In conclusion, we demonstrated the comprehensive within-host evolutionary dynamics of A. baumannii, and discovered a key mutation of BauA site 391 as a genetic switch to adapt to different pH values, which may represent a model in the pathogen evolutionary adaption of the host microenvironment.

Jiayao Guan,1,* Chunmei Bao,2,* Peng Wang,3 Ying Jing,3 Lingling Wang,3 Xinyue Li,3 Xiaofei Mu,3 Boan Li,2 Dongsheng Zhou,3 Xuejun Guo,1 Zhe Yin3 1Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, Jilin, 130122, People’s Republic of China; 2Fifth Medical Center of Chinese PLA General Hospital, Beijing, 100039, People’s Republic of China; 3State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhe Yin, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, People’s Republic of China, Tel +86-10-66948557, Email jerry9yin@163.com Xuejun Guo, Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, Jilin, 130122, People’s Republic of China, Tel +86-431-86985931, Email xuejung2021@163.comPurpose: The aim of this study was to gain a deeper genomics and bioinformatics understanding of diversification of accessory genetic elements (AGEs) in Providencia.Methods: Herein, the complete genome sequences of five Providencia isolates from China were determined, and seven AGEs were identified from the chromosomes. Detailed genetic dissection and sequence comparison were applied to these seven AGEs, together with additional 10 chromosomal ones from GenBank (nine of them came from Providencia).Results: These 17 AGEs were divided into four groups: Tn 6512 and its six derivatives, Tn 6872 and its two derivatives, Tn 6875 and its one derivative, and Tn 7 and its four derivatives. These AGEs display high-level diversification in modular structures that had complex mosaic natures, and particularly different multidrug resistance (MDR) regions were presented in these AGEs. At least 52 drug resistance genes, involved in resistance to 15 different categories of antimicrobials and heavy metal, were found in 15 of these 17 AGEs.Conclusion: Integration of these AGEs into the Providencia chromosomes would contribute to the accumulation and distribution of drug resistance genes and enhance the ability of Providencia isolates to survive under drug selection pressure.Keywords: Providencia, integrative and conjugative elements, integrative and mobilizable elements, unit transposons, multidrug resistance

Objective Invasive candidiasis (IC), a life-threatening fungal infection prevalent among hospitalized patients, has highly variable regional epidemiology. We conducted a multicenter surveillance study to investigate recent trends in species distribution and antifungal susceptibility patterns among IC-associated Candida spp. in Beijing, China, from 2016 to 2017. Materials and Methods A total of 1496 non-duplicate Candida isolates, recovered from blood and other sterile body fluids of IC patients, were identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry combined with ribosomal DNA internal transcribed spacer (ITS) region sequencing. Broth microdilution-based susceptibility testing using six antifungal agents was also conducted. Results Candida albicans was the most frequently isolated species (49.9%), followed by Candida tropicalis (15.5%), Candida glabrata (14.7%) and Candida parapsilosis (14.2%). No significant differences in species distribution were observed when compared with a 2012-2013 dataset. Overall, the rates of susceptibility to fluconazole and voriconazole were high among C. albicans (98% and 97.2%, respectively) and C. parapsilosis species complex (91.1% and 92%, respectively) isolates but low among C. tropicalis (81.5% and 81.1%, respectively) isolates. In addition, the rate of azole resistance among C. tropicalis isolates increased significantly (1.8-fold, P

Objective The main objective of this study was to investigate the ameliorative effects of Palmatine (Pal) on Helicobacter pylori (H. pylori) induced chronic atrophic gastritis (CAG). Method Body function, serum biochemical indicators and histopathology were used to evaluate the pharmacodynamics of Pal on CAG rats. The target genes expression levels were verified and assessed by RT-PCR and immunohistochemistry (IHC). Moreover, UPLC-Q-TOF/MS analysis based on urine and serum was performed to identify the potential metabolites in the pathological process of CAG induced by H. pylori. Metabolic pathway analysis was performed to elucidate the metabolic network associated with Pal treatment of CAG. Results Pal (10, 20, 40 mg/kg/day) significantly restored the body function of CAG rats, reduced the serum biochemical indicators, and maintained the integrity of the gastric mucosal epithelial barrier while alleviated gastric histological damage. Metabolomics analysis shows that the therapeutic effect of Pal on CAG involves 10 metabolites and 10 metabolic pathways, of which the Taurine and hypotaurine metabolism, Glycerophospholipid metabolism and Pentose and glucuronate interconversions are closely related to the gastrointestinal protection of Pal, and these metabolic pathways crosstalk with each other due to the internet hub of citric acid cycle. Conclusions Metabolomics was used for the first time to identify potential biomarkers of CAG and to illuminate the therapeutic mechanism of Pal on CAG induced by H. pylori. The results provided a new insight for further research on CAG treatment.

Background: Zuojin Pill (ZJP), a famous Chinese medicinal formula, is widely accepted for treatment of chronic atrophic gastritis (CAG) in China. This study aimed to explore the therapeutic effects and mechanisms of ZJP in Helicobacter pylori (H. pylori) - induced chronic atrophic gastritis (CAG) in vivo and in vitro. Methods: CAG rat model was induced by H. pylori. ZJP (0.63, 1.26, and 2.52 g/kg, respectively) was administered orally for four weeks. Therapeutic effects of ZJP were identified by H&E staining and serum indices. In addition, cell viability, morphology and proliferation were detected by cell counting kit-8 (CCK8) and high-content screening assay (HCS), respectively. Moreover, relative mRNA expression and protein expression related to JMJD2B/COX-2/VEGF axis was detected to investigate the potential mechanisms of ZJP in CAG.Results: Results showed the symptoms (weight loss and gastric mucosa damage) of CAG were alleviated, and the contents of TNF-α in serum was markedly decreased after treating with ZJP. Moreover, cell viability, proliferation and morphology changes of GES-1 cells were ameliorated by ZJP intervention. In addition, proinflammatory genes and JMJD2B/COX-2/VEGF axis related genes were suppressed by ZJP administration in vitro and in vivo. Meanwhile, immunohistochemistry (IHC) and western blot confirmed down-regulation of these genes by ZJP intervention. Conclusion: ZJP treatment can alleviate gastric mucosal damage induced by H. pylori via JMJD2B/COX-2/VEGF axis.

Background: Zuojin Pill (ZJP), a famous Chinese medicinal formula, widely accepted for treatment of chronic atrophic gastritis (CAG) in China. This study aimed to explore the therapeutic effects and mechanisms of ZJP in Helicobacter pylori (H. pylori) - induced chronic atrophic gastritis (CAG) in vivo and in vitro. Methods: CAG rat model was induced by H. pylori. ZJP (0.63, 1.26, and 2.52 g/kg, respectively) was administered orally for four weeks. Therapeutic effects of ZJP were identified by H&E staining and serum indices. In addition, cell viability, morphology and proliferation were detected by cell counting kit-8 (CCK8) and high-content screening assay (HCS), respectively. Moreover, relative mRNA expression and protein expression related to JMJD2B/COX-2/VEGF axis was detected to investigate the potential mechanisms of ZJP in CAG. Results: Results showed the symptoms (weight loss and gastric mucosa damage) of CAG were alleviated, and the contents of TNF-α in serum was markedly decreased after treating with ZJP. Moreover, cell viability, proliferation and morphology changes of GES-1 cells were ameliorated by ZJP intervention. In addition, proinflammatory genes and JMJD2B/COX-2/VEGF axis related genes were suppressed by ZJP administration in vitro and in vivo. Meanwhile, immunohistochemistry (IHC) and western blot confirmed down-regulation of these genes by ZJP intervention. Conclusion: ZJP treatment can alleviate gastric mucosal damage induced by H. pylori via JMJD2B/COX-2/VEGF axis.

Objective Zuojin Pill (ZJP) containing two Chinese herbal drugs: Coptidis Rhizoma and Euodiae Fructus is a classical formula and is widely accepted as a treatment of chronic atrophic gastritis (CAG) in China. This study aimed to explore the therapeutic effect and mechanism of ZJP which attenuated H. pylori -induced CAG in vivo and in vitro.Methods: H. pylori (Helicobacter pylori) was used to induce CAG rat model. 0.63, 1.26, and 2.52 g/kg of ZJP (was administered orally for four weeks. Therapeutic effect of ZJP was identified by H & E staining and serum indices. In addition, cell viability, morphology and proliferation were detected by cell counting kit-8 and high-content screening assay. Gene and protein expression related to JMJD2B/COX-2/VEGF axis were detected to further investigate the potential mechanism.Results Compared with the control group, the ZJP groups showed a significant protection effects on Gastric mucosa, as indicated by the reduced loss of glands and inflammatory cell infiltration. Meanwhile, ZJP could ameliorate cell viability, morphology changes, and proliferation in GES-1 cells. Moreover, the ZJP treatment decreased the amount of IL-8, and TNF-α, indicating that it could reduce the level of inflammation, and decrease stomach damage. The expression of JMJD2B/COX-2/VEGF axis related genes and proteins were measured by real-time quantitative PCR, western blot and immunohistochemistry methods. The ZJP groups were found to decrease relative genes and protein expression level compared with the model group. ZJP could improve gastric mucosa protection and reduce inflammation level by inhibiting the expression level of JMJD2B/COX-2/VEGF axis.Conclusion Our data confirmed the effective therapy of ZJP in H. pylori -induced CAG, which supports the role of ZJP as an anti-inflammatory and protection of gastric mucosa agent in CAG induced by H. pylori . These results may provide helpful tools for the treatment of CAG.

Aims In this study, we will investigate the therapeutic effects of berberine (BBR) in Helicobacter pylori (H. pylori) induced chronic atrophic gastritis (CAG). Furthermore, potential mechanisms of BBR in regulating IRF8-IFN-γ signaling axis will also be investigated. Materials and methods H. pylori were utilized to establish CAG model of rats. Therapeutic effects of BBR on serum supernatant indices, and histopathology of stomach were analyzed in vivo. Moreover, GES-1 cells were infected by H. pylori, and intervened with BBR in vitro. Cell viability, morphology, proliferation, and quantitative analysis were detected by high-content screening (HCS) imaging assay. To further investigate the potential mechanisms of BBR, relative mRNA, immunohistochemistry and protein expression in IRF8-IFN-γ signaling axis were measured. Key findings Results showed serum supernatant indices including IL-17, CXCL1, and CXCL9 were downregulated by BBR intervention, while, G-17 increased significantly. Histological injuries of gastric mucosa induced by H. pylori also were alleviated. Moreover, cell viability and morphology changes of GES-1 cells were improved by BBR intervention. In addition, proinflammatory genes and IRF8-IFN-γ signaling axis related genes, including Ifit3, Upp1, USP18, Nlrc5, were suppressed by BBR administration in vitro and in vivo. The proteins expression related to IRF8-IFN-γ signaling axis, including Ifit3, IRF1 and Ifit1 were downregulated by BBR intervention.

Background Klebsiella pneumoniae exhibits prevalence in China. Little is known about the microbiological characterization of clinical K . pneumoniae isolates causing bloodstream infections (BSIs). Methods BSI-causing K . pneumoniae (BSIKpn) isolates were collected from five tertiary-care hospitals in Beijing, China. Their genetic relatedness was analyzed by pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility was determined by agar dilution method, and sequence type (ST) was evaluated by multilocus sequence typing (MLST). The hypermucoviscosity (HV) phenotype was identified by a positive string test. Carbapenemase, capsular serotypes and HV-associated genes were detected by PCR amplification. Results A total of 219 non-duplicated BSIKpn isolates were collected from Dec. 2013 to Dec. 2014 and categorized into 203 types (strains) which had a unique PFGE pattern. Among 203 BSIKpn strains, 105 different STs were identified. Overall, ST11 and ST23 were the predominant clones and detected from 14 strains (6.9%), respectively, followed by ST412 ( n = 13), ST37 ( n = 9), ST65 ( n = 7), ST15 ( n = 6), ST86 ( n = 6), ST592 ( n = 5) and ST29 ( n = 4). There were 74 STs containing only a single strain. Approximately 8.4% (17/203) of BSIKpn strains exhibited resistance to carbapenem and most of them produced K . pneumoniae carbapenemase (KPC). The majority (70.4%, 143/203) of BSIKpn isolates were associated with non-K1/K2/K5/K20/K54/K57 serotypes. Only 16.7% (34/203) of BSIKpn strains had K1/K2 serotypes. A total of 66 (32.5%) of the BSIKpn strains exhibited HV phenotype. The rmpA was a predominant factor in determining whether or not a BSIKpn strain had HV phenotype. Conclusions The majority of BSIKpn strains exhibited high level of genetic diversity and low resistance to commonly used antimicrobial agents. The specific capsular serotype and HV phenotype were not the major features of BSIKpn strains from China.

The spread of the plasmid-mediated colistin resistance gene, mcr-1 , into carbapenem-resistant Enterobacteriaceae (CRE) clinical isolates poses a significant threat to global health. Here we report the identification of three mcr-1 -harboring carbapenem-resistant Escherichia coli strains, collected from three patients in two provinces in China. Our results show that mcr-1 -harboring CRE strains have started to spread in different hospitals in China. In addition, this report presents the first description of chromosomal integration of mcr-1 into a carbapenem-resistant E. coli strain.

Bloodstream infections (BSIs) are a frequently observed complication in liver cirrhosis patients. This study aimed to investigate the microbiological characteristics and outcomes of BSIs in patients with liver cirrhosis. We retrospectively studied 852 patients with liver cirrhosis who developed a BSI. Patient outcome was evaluated using 30-day mortality and assessed using multivariate stepwise logistic regression analysis. Antibiotic sensitivity of the pathogens was tested. Gram-negative bacteria were responsible for 59.6% of BSIs, and Gram-positive bacteria caused 40.4% of the episodes among liver cirrhosis patients. The bacterial distribution significantly differed between hospital-acquired and community-acquired infections, especially in cases caused by Gram-negative pathogens. The results of the drug sensitivity test suggested that amikacin, cefoperazone/sulbactam, and piperacillin/tazobactam highly suppressed Gram-negative infections, while vancomycin and teicoplanin strongly inhibited Gram-positive BSIs. Liver failure, liver cancer, complications, Child-Pugh grade, septic shock, administration of appropriate antibiotics within 24 h, ICU admission, nosocomial infection, and Gram nature of the bacteria were independent risk factors for 30-day mortality (P

Polymorphonuclear neutrophils (PMNs) and proinflammatory cytokines have been implicated in the pathogenesis of acute-on-chronic liver failure (ACLF). But the utility of CXC chemokine receptor expression on PMNs as a biomarker for prediction of disease severity is still uncertain. In this study, we investigated the dynamic expression of CXCR1 and CXCR2 on neutrophils, and found that patients with hepatitis B virus-related ACLF displayed low expression of CXCR1 and CXCR2 on peripheral neutrophils compared with healthy subjects and patients with chronic hepatitis B. This expression pattern was correlated with disease severity. Additionally, increased production of IL-8 in peripheral blood was significantly associated with reduced CXCR1 and CXCR2 expression, as shown by the decreased CXCR1 and CXCR2 expression on neutrophils after treating neutrophils with plasma from ACLF patients. This effect could be overcomed through IL-8 blockage with an anti-IL-8 antibody. We also found that IL-8 production and neutrophil infiltration were coordinately increased in the liver tissue of HBV-ACLF patients, and this increase was associated with liver inflammation. Overall, increased production of IL-8 associated with neutrophils infiltration into the liver and decreased CXCR1/2 expression on peripheral neutrophils. CXCR1 and CXCR2 expression levels could be served as early markers to predict the severity of ACLF.

Shigella sonnei has become the dominant serotype causing shigellosis in Asian countries in recent years. In this study, we characterize the increasing trend of antibiotic resistance profiles and genotypes of S. sonnei isolates in the Beijing area. From January 2002 to December 2007, a total of 1108 Shigella isolates including 362 S. sonnei were recovered from diarrhea patients at the 302nd Hospital in Beijing. While the frequency of S. flexneri gradually decreased, S. sonnei gradually increased and became the dominant species. A total of 362 S. sonnei isolates were further analyzed for their antimicrobial profiles and 272 revived isolates were selected for genotyping analysis, respectively. High-level antimicrobial resistances were observed in sulfamethoxazole/trimethoprim (94.5%), ampicillin (40.3%), piperacillin (36.5%), and ceftriaxone (12.8%) with significant single- and multiple-drug resistance increase trends from 2002 to 2007 ( P = 0.0000). Pulsed-field gel electrophoresis analysis indicated that 263 (96.7%) S. sonnei belonged to 1 clonal genotype A, which were further divided into A1–A6 subtypes. While subtype A2 was dominant in the early stage of study years, subtype A4 started to emerge and increased significantly in later years. Antimicrobial resistance rates are statistically different among the 6 subtypes ( P = 0.0000), and A4 possessed the highest resistance rates to ampicillin (83.7%) and piperacillin (81.4%). Subtype A3 was highly clustered in inpatients compared to other subtypes ( P = 0.0145). This study indicates that a clonal S. sonnei strain has become dominant in the Beijing area, and subtype A4 is responsible for increased antibiotic resistance.

Sepsis is a life-threatening medical condition that triggers an uncontrolled inflammatory reaction and is caused by the entry of various microorganisms into the human bloodstream. Sepsis is mainly encountered in intensive care units (ICUs) due to the reduced immunological defenses of ICU patients. Approximately 1.5 million patients develop sepsis annually in industrialized countries, and the mortality rate is very high (30–50%).1 Thus, the treatment of sepsis represents a major unmet medical need.

This is the first reported case of liver abscess attributable to Salmonella serovar Dublin infection and also the fourth case of Salmonella liver abscess complicated with hepatocellular carcinoma reported since 1990. Drainage combined with intravenous antibiotics resulted in improvement, but recovery regressed again. Subsequent hepatic left lobectomy led to full recovery.

Objective Periploca forrestii Schltr has been used as a Chinese folk medicine for the treatment of rheumatism, arthralgia and fractures. However, the anti-arthritic activity of Periploca forrestii saponin (PFS) and the active compound has still not been revealed. This study aimed to investigate the protective effects and mechanisms of PFS on collagen type II (CII) collagen-induced arthritis (CIA) mice. We sought to investigate whether PFS and Periplocin could regulate osteoclastogenesis, and if so, further investigation on its mechanism of action. Methods Arthritis was induced in female BALB/c mice by CIA method. PFS was administered at a dose of 50 mg/kg body weight once daily for five weeks. The effects of treatment in mice were assessed by histological and biochemical evaluation in sera and paws. Anti-osteoclastogenic action of PFS and Periplocin was identified using an osteoclast formation model induced by RANKL. Results PFS ameliorated paw erythema and swelling, inhibited bone erosion in ankle joint histopathological examination. PFS treatment resulted in decreased IgG2a, and increased IgG1 levels in the serum of CIA mice. Decreased TNF-α, and increased interleukin (IL)-4 and IL-22 levels were also found in PFS-treated mice. PFS inhibited the I-κBα phosphorylation, blocked nuclear factor (NF)-κB/p65 phosphorylation and abrogated AP-1/c-Fos activity. PFS downregulated toll-like receptor (TLR) 4, STAT3 and MMP-9 expression in CIA mice and RANKL-induced osteoclastogenesis. PFS and Periplocin inhibited RANKL-induced osteoclast formation in a dose dependent manner within nongrowth inhibitory concentration, and PFS decreased osteoclastogenesis-related marker expression, including cathepsin K and MMP-9. Conclusion This study revealed that the protective mechanism of PFS on CIA was associated with regulatory effects on proinflammatory factors and further on the crosstalk between NF-κB and c-Fos/AP-1 in vivo and in vitro. Therefore, PFS is a promising therapeutic alternative for the treatment of RA, evidencing the need to conduct further studies that can identify their active components in treating and preventing RA.

Background: Sepsis encompasses two phases, the ‘hyper’-reactive phase and the ‘hypo’-reactive phase. The initial inflammatory stage is quickly counterbalanced by an anti-inflammatory response, which compromises the immune system, leading to immune suppression. Regulatory T cells (Tregs) have been implicated in the pathogenesis of sepsis by inducing immunosuppression; however, the role of CD39+ Tregs in the process of sepsis is uncertain. This study investigated the dynamic levels of CD39+ Tregs and their phenotypic change in sepsis. Methods: Fourteen patients with systemic inflammatory response syndrome (SIRS), 42 patients with sepsis, and 14 healthy controls were enrolled. Sequential blood samples were used to analyze the numbers of CD39+ Tregs and their phenotypic changes. Survival at 28 days was used to evaluate the capacity of CD39+ Treg levels to predict mortality in sepsis patients. Results: Sepsis patients displayed a high percentage (3.13%, 1.46%, and 0.35%, respectively) and mean fluorescence intensity (MFI) (59.65, 29.7, and 24.3, respectively) of CD39+ Tregs compared with SIRS patients and healthy subjects. High-level expression of CD39+ Tregs was correlated with the severity of sepsis, which was reflected by the sepsis-related organ failure assessment score (r = 0.322 and r = 0.31, respectively). In addition, the expression of CD39+ Tregs was associated with survival of sepsis patients (p 4.1%) and MFI (p 49.2) were significantly associated with mortality. Phenotypically, CD39+ Tregs from sepsis patients showed high expression of CD38 and PD-1 (p

Complement 5a (C5a) has been implicated in the pathogenesis of sepsis by inducing the functional impairment of neutrophils; however, the utility of C5a receptors (C5aRs; C5aR and C5L2) as biomarkers for the management of sepsis is uncertain. This study investigated the dynamic expression of C5aR and C5L2 on neutrophils and their effects on neutrophil function. We found that sepsis patients displayed low expression levels of C5aR and C5L2 on neutrophils compared to healthy and systemic inflammatory response syndrome (SIRS) subjects, and this expression pattern was correlated with disease severity. Additionally, the expression levels of C5aR and C5L2 were associated with the survival of sepsis patients. In vitro, the addition of C5a significantly reduced C5aR and C5L2 expression levels and IL-8 production in neutrophils from sepsis patients. Those findings suggest that the reduced expression of C5aRs was associated with the functional impairment of neutrophils and a poor prognosis for sepsis patients. Overall, these findings may help establish C5aRs expression levels as early markers to predict the severity of sepsis.

Military facilities provide unique opportunities for studying Staphylococcus aureus nasal colonization and transmission patterns. In this cross-sectional observational study, we assessed the prevalence of S. aureus nasal colonization among Chinese military volunteers in two camps in the Beijing area. Antimicrobial resistance patterns, risk factors for colonization, and transmission patterns using pulsed-field gel electrophoresis were also evaluated. From May to July 2007, 1,044 nasal swabs were collected from military volunteers from suburban (560) and urban (484) camps. A total of 209 S. aureus isolates were recovered, of which all were methicillin susceptible. Independent factors associated with methicillin-susceptible S. aureus (MSSA) nasal colonization included younger age (odds ratio [OR] = 1.51, 95% confidence interval [95% CI] = 1.03 to 2.21, P = 0.0347), higher education (OR = 1.38, 95% CI = 1.10 to 1.73, P = 0.0056), shorter length of service (OR = 1.74, 95% CI = 1.28 to 2.36, P = 0.0004), nonsmoking (OR = 1.61, 95% CI = 1.14 to 2.28, P = 0.0069), and inactive participation in social events (OR = 2.40, 95% CI = 1.25 to 5.49, P = 0.0082). Among 209 MSSA isolates, 126 (60.3%) were determined to be epidemic and a total of 12 genotypes were identified, of which four (90 isolates [71.4%]) represented the majority of strains. Length of service and camp location were statistically related to the four major MSSA genotype clonal transmissions. Our data indicated that MSSA, not methicillin-resistant S. aureus (MRSA), nasal colonization and clonal transmission occur in healthy military volunteers in Beijing. Younger, female, nonsmoking volunteers with higher education, little or no participation in social events, and less time in service are at higher risk for nasal MSSA carriage.

Shigella species are a common cause of acute diarrheal disease in China. In this study, we characterized the changing trends and serotype distribution of Shigella species in Beijing from 1994 to 2010. A total of 5999 Shigella strains were isolated and serotyped from the 302nd Hospital in Beijing. The annual number of Shigella isolates reached a peak (n = 1192; 19.84%) in 1996 and then decreased annually, reaching the lowest point (n = 24; 0.41%) in 2010. S. flexneri 2a and S. sonnei were the most frequently isolated Shigella, with their respective isolates making up 53.3% and 27.6% of the total. Isolates of S. flexneri 4c, 4a, and x made up 3% respectively of the total isolates. Significant decreases in percentage of S. flexneri over time were observed. S. sonnei surpassed S. flexneri 2a as the predominant serotype in 2000. Most isolates were recovered from July to September; 13.6% of the isolates were recovered from children aged 0 to 5 years, and 16% were recovered from those aged 21 to 25 years. S. flexneri 2a and 5 were recovered mostly from males (33.41%, p p S. flexneri 2b and 6, and S. sonnei were most often isolated from females. Continuous monitoring of Shigella showed that all 4 species and 27 serotypes were present in Beijing, China, during the study period. The emergence of S. sonnei and the overall decreasing isolation rate of Shigella in Beijing can potentially aid in the development of vaccine and control strategies for shigellosis in the city.