N-dodecanoyl-l-homoserine lactone (C12-HSL) is a signaling molecule that mediates bacterial quorum sensing, regulating bacterial population behaviors. This study investigated the effects of C12-HSL on the isolation and cultivation of gut microbiota, with the goal of enriching the diversity and number of cultivable bacterial strains from the mouse gut microbiota. Using a culture medium supplemented with C12-HSL, we isolated and cultivated bacterial strains from mouse intestinal contents, obtaining a total of 235 isolates. Preliminary identification based on the 16S rRNA gene revealed 54 bacterial species, including 4 potential new species, 4 potential new genera and 1 potential new family. Compared with the previously established mouse gut microbial biobank (mGMB), this study newly identified 42 bacterial species, enhancing the diversity of the strain library. Statistical analysis showed that the proportion of Gram-negative bacteria, particularly those belonging to Proteobacteria, isolated by this method was significantly higher than that obtained by conventional isolation and cultivation methods without the addition of C12-HSL. Subsequent cultivation experiments with one of the newly discovered bacterial species indicated that exogenous C12-HSL at 20-200 μmol/L significantly promoted the growth of this species, while higher concentrations of C12-HSL significantly reduced the cell density of this bacterium. This work confirms that quorum sensing molecules, such as C12-HSL, can enhance the growth, isolation, and cultivation of Gram-negative bacteria in the gut within a specific concentration range. Although the mechanism by which C12-HSL promotes the growth of gut bacterial strains requires further investigation, the findings of this study provide new insights into the targeted isolation, cultivation, and regulation of gut microbiota using bacterial quorum sensing signal molecules.
Animals ; Mice ; Acyl-Butyrolactones/pharmacology* ; Gastrointestinal Microbiome/drug effects* ; Quorum Sensing ; Gram-Negative Bacteria/classification* ; Intestines/microbiology* ; RNA, Ribosomal, 16S/genetics* ; Culture Media

OBJECTIVETo explore the distribution and antibiotic resistance of pathogens in lesions of diabetic foot osteomyelitis (DFO) and analyze the risk factors causing osteomyelitis.

METHODSA total of 372 patients with diabetic foot infections hospitalized between January 2011 and December 2014, including 203 with osteomyelitis (OM group) and 169 without osteomyelitis (non-OM group), were examined for the distribution and antibiotic resistance profile of the pathogens in the wounds. Logistic regression analysis was used to analyze the risk factors causing osteomyelitis.

RESULTSGram-negative bacteria were the predominant pathogens (53.7%) in the infected wounds in OM group, whereas Gram-positive bacteria were the most frequently found (56.7%) in non-OM group (P=0.001). Among the Gram-positive bacteria, Staphylococcus was the dominating flora (35.1%). The resistance rate to oxacillin and cefoxitin of the isolated bacteria in OM group (64.9% and 68.5%, respectively) was significantly higher than that in non-OM group (29.2% and 32.6%, respectively; P<0.05). Among the gram-negative bacteria, Enterobacteriaceae was the dominating flora (62.4%), with a higher resistance rate to Cefepime and Aztreonam in OM group (30.1% and 38.6%, respectively) than in non-OM group (15.1% and 22.2%, respectively; P<0.05). Logistic regression analysis indicated that the infection by multi-drug resistant bacteria and an wounds area >4 cm(2) were the risk factors for osteomyelitis in patients with diabetic foot infections (P<0.05).

CONCLUSIONIn addition to an empirical anti-infection therapy, clinicians should choose specific antibiotics against Gram-negative bacteria according to the microbial spectrum and antibiotic resistance of pathogens in patients with DFO; patients with diabetic foot infections by multi-drug resistant bacteria and those with a wound area exceeding 4 cm(2) are exposed to an increased risk of osteomyelitis.

Anti-Bacterial Agents ; Cephalosporins ; Diabetic Foot ; microbiology ; Drug Resistance, Multiple, Bacterial ; Gram-Negative Bacteria ; classification ; isolation & purification ; Gram-Positive Bacteria ; classification ; isolation & purification ; Humans ; Osteomyelitis ; microbiology ; Risk Factors ; Wound Infection ; microbiology

The trends and types of carbapenemase-producing Gram-negative bacilli were analyzed from clinical specimens collected between 2005 and 2012 at a Korean teaching hospital. The proportions of carbapenem-resistant Acinetobacter spp. increased markedly to 66%. Metallo-beta-lactamase producers significantly decreased and the majority shifted from the bla(VIM-2) type to the bla(IMP-1) type.
Acinetobacter/classification/drug effects/*enzymology ; Acinetobacter Infections/drug therapy ; Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins ; Carbapenems/*pharmacology ; Drug Resistance, Microbial ; Gram-Negative Bacteria/*drug effects/enzymology/isolation & purification ; Humans ; Incidence ; Microbial Sensitivity Tests/trends ; Population Surveillance ; Pseudomonas/classification/drug effects/enzymology ; Republic of Korea/epidemiology ; beta-Lactamases/biosynthesis/*drug effects

BACKGROUNDThe Study for Monitoring Antimicrobial Resistance Trends program monitors the activity of antibiotics against aerobic and facultative Gram-negative bacilli (GNBs) from intra-abdominal infections (IAIs) in patients worldwide.

METHODSIn 2011, 1 929 aerobic and facultative GNBs from 21 hospitals in 16 cities in China were collected. All isolates were tested using a panel of 12 antimicrobial agents, and susceptibility was determined following the Clinical Laboratory Standards Institute guidelines.

RESULTSAmong the Gram-negative pathogens causing IAIs, Escherichia coli (47.3%) was the most commonly isolated, followed by Klebsiella pneumoniae (17.2%), Pseudomonas aeruginosa (10.1%), and Acinetobacter baumannii (8.3%). Enterobacteriaceae comprised 78.8% (1521/1929) of the total isolates. Among the antimicrobial agents tested, ertapenem and imipenem were the most active agents against Enterobacteriaceae, with susceptibility rates of 95.1% and 94.4%, followed by amikacin (93.9%) and piperacillin/tazobactam (87.7%). Susceptibility rates of ceftriaxone, cefotaxime, ceftazidime, and cefepime against Enterobacteriaceae were 38.3%, 38.3%, 61.1%, and 50.8%, respectively. The leastactive agent against Enterobacteriaceae was ampicillin/sulbactam (25.9%). The extended-spectrum β-lactamase (ESBL) rates among E. coli, K. pneumoniae, Klebsiella oxytoca, and Proteus mirabilis were 68.8%, 38.1%, 41.2%, and 57.7%, respectively.

CONCLUSIONSEnterobacteriaceae were the major pathogens causing IAIs, and the most active agents against the study isolates (including those producing ESBLs) were ertapenem, imipenem, and amikacin. Including the carbapenems, most agents exhibited reduced susceptibility against ESBL-positive and multidrug-resistant isolates.

Anti-Bacterial Agents ; pharmacology ; China ; Enterobacteriaceae ; classification ; drug effects ; genetics ; pathogenicity ; Gram-Negative Bacteria ; classification ; genetics ; Gram-Negative Bacterial Infections ; microbiology ; Humans ; Intraabdominal Infections ; microbiology ; Microbial Sensitivity Tests

Bacterial biofilms have emerged as potential critical triggers in the pathogenesis of bisphosphonate (BP)-related osteonecrosis of the jaw (ONJ) or BRONJ. BRONJ lesions have shown to be heavily colonized by oral bacteria, most of these difficult to cultivate and presents many clinical challenges. The purpose of this study was to characterize the bacterial diversity in BRONJ lesions and to determine host immune response. We examined tissue specimens from three cohorts (n=30); patients with periodontal disease without a history of BP therapy (Control, n=10), patients with periodontal disease having history of BP therapy but without ONJ (BP, n=5) and patients with BRONJ (BRONJ, n=15). Denaturing gradient gel electrophoresis of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments revealed less bacterial diversity in BRONJ than BP and Control cohorts. Sequence analysis detected six phyla with predominant affiliation to Firmicutes in BRONJ (71.6%), BP (70.3%) and Control (59.1%). Significant differences (P<0.05) in genera were observed, between Control/BP, Control/BRONJ and BP/BRONJ cohorts. Enzyme-linked immunosorbent assay (ELISA) results indicated that the levels of myeloperoxidase were significantly lower, whereas interleukin-6 and tumor necrosis factor-alpha levels were moderately elevated in BRONJ patients as compared to Controls. PCR array showed significant changes in BRONJ patients with downregulation of host genes, such as nucleotide-binding oligomerization domain containing protein 2, and cathepsin G, the key modulators for antibacterial response and upregulation of secretory leukocyte protease inhibitor, proteinase 3 and conserved helix-loop-helix ubiquitous kinase. The results suggest that colonization of unique bacterial communities coupled with deficient innate immune response is likely to impact the pathogenesis of ONJ.
Actinobacteria ; classification ; Bacteria ; classification ; Bacteroidetes ; classification ; Biofilms ; Bisphosphonate-Associated Osteonecrosis of the Jaw ; immunology ; microbiology ; Bone Density Conservation Agents ; therapeutic use ; Cathepsin G ; analysis ; Cohort Studies ; Down-Regulation ; Female ; Fusobacteria ; classification ; Gram-Negative Bacteria ; classification ; Host-Pathogen Interactions ; immunology ; Humans ; I-kappa B Kinase ; analysis ; Immunity, Innate ; immunology ; Interleukin-6 ; analysis ; Male ; Middle Aged ; Mouth ; immunology ; microbiology ; Myeloblastin ; analysis ; antagonists & inhibitors ; Nod2 Signaling Adaptor Protein ; analysis ; Periodontal Diseases ; microbiology ; Peroxidase ; analysis ; Proteobacteria ; classification ; Tumor Necrosis Factor-alpha ; analysis

Phosphatases play a key role not only in cell physiological functions of an organism, but also in host-pathogen interactions. Many studies demonstrated that some Gram-negative pathogenic bacteria could evade host immunity and promote pathogenicity by injecting phosphatases into host cells through type III secretion system. However, there were few reports about pathogenic fungi evading the immunity of hosts. Our researches indicated that the entomogenic fungus Metarhizium anisopliae could dephosphorylate the signal transduction substance of locust humoral immunity specifically in vitro by secreting extracellular protein tyrosine phosphatase, which implied that the fungus might interfere with the immune defense of locust. To provide reference for further studies of the functions of phosphatases, we reviewed the types of phosphatases and their roles in pathogen infection.
Animals ; Fungal Proteins ; metabolism ; Fungi ; enzymology ; physiology ; Gram-Negative Bacteria ; enzymology ; physiology ; Grasshoppers ; immunology ; microbiology ; Host-Pathogen Interactions ; Metarhizium ; enzymology ; Phosphoric Monoester Hydrolases ; classification ; physiology ; secretion

OBJECTIVETo investigate the antimicrobial activity of methanolic extracts of different parts of Ixora species.

METHODSAntimicrobial activity was carried out using disc diffusion assay against fungi, gram-positive and gram-negative bacteria.

RESULTSAll methanolic extracts of different parts of Ixora species showed a broad-spectrum of antibacterial and antiyeast activities, which inhibited the growth of at least one bacterium or yeast. There was no remarkable difference between different Ixora species observed in this study.

CONCLUSIONSThe significant antimicrobial activity shown by this Ixora species suggests its potential against infections caused by pathogens. The extract may be developed as an antimicrobial agent.

Anti-Bacterial Agents ; pharmacology ; Antifungal Agents ; pharmacology ; Fungi ; drug effects ; Gram-Negative Bacteria ; drug effects ; Gram-Positive Bacteria ; drug effects ; Microbial Sensitivity Tests ; Phytotherapy ; Plant Extracts ; pharmacology ; Rubiaceae ; classification ; metabolism

BACKGROUND: Procedures for rapid identification and susceptibility testing by direct inoculation (DI) from positive blood culture bottles into an automated system have not been standardized. This study was purposed to evaluate DI from BACTEC 9240 blood culture system (BD, USA) into MicroScan (Dade Behring, USA) or Phoenix (BD, USA). METHODS: From May to June 2006, bacterial pellets from positive aerobic bottles showing gram-positive cocci (GPC) or gram-negative rods (GNR) of single morphology were directly inoculated to MicroScan PosCombo1A and NegCombo32 and to Phoenix PMIC/ID-107 and NMIC/ID-53. In addition, the automated instruments were also inoculated from subcultures (standard inoculations, SI). Species identification and susceptibilities were compared between DI and SI and between MicroScan and Phoenix. RESULTS: A total of 108, 104, and 78 specimens were tested with MicroScan, Phoenix, and both, respectively. When DI and SI were matched, 94.8% of GPC were correctly identified with MicroScan, compared to 80.7% with Phoenix, and 93.9% of GNR were correctly identified with MicroScan, compared to 95.7% with Phoenix. DI with MicroScan and Phoenix showed correct susceptibilities in 94.6% of 1,150 and 96.5% of 660 tests (with very major error [VME] of 1.1% and 1.1%), respectively, among GPC and in 94.4% of 942 and 96.3% of 781 tests (with VME of 0.6% and 0%), respectively, of GNR. Correlation of identification/susceptibilities between MicroScan and Phoenix using DI were 81.8%/98.0% for Staphylococcus aureus and 100.0%/95.6% for Escherichia coli. CONCLUSIONS: DI warrants a reliable method for identification and susceptibility testing of both GPC and GNR in MicroScan, and those of only GNR in Phoenix.
Automation ; Bacterial Typing Techniques/instrumentation/*methods ; Culture Media ; Gram-Negative Bacteria/*classification/drug effects/isolation & purification ; Gram-Negative Bacterial Infections/blood/*microbiology ; Gram-Positive Bacterial Infections/blood/*microbiology ; Gram-Positive Cocci/*classification/drug effects/isolation & purification ; Humans ; Microbial Sensitivity Tests/instrumentation/*methods ; Reagent Kits, Diagnostic ; Sensitivity and Specificity

OBJECTIVEBioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams.

METHODSThe nickel-resistant bacterial isolates (NiRBI) were selected from various bacterial isolates from industrial effluent and grown in nutrient broth containing different concentrations of nickel sulfate (0.3-3.0 mmol/L) and their capability of accumulating metal from the medium.

RESULTSWell-defined growth of NiRBI was observed in the medium containing up to 2.5 mmol/L of nickel. The isolate was identified using 16S rRNA and closely related to Pseudomonas fragi. Maximum accumulation of nickel (0.59 mg/g dry weight of bacterial cells) was observed when NiRBI was grown in media containing 2 mmol/L of nickel. The protein profile of the NiRBI cellular extract by SDS-PAGE showed two metal stress-induced proteins of molecular weight 48 KD and 18 KD with a simultaneous down regulation of four proteins of 46.7 KD, 42.2 KD, 19.7 KD, and 4.0 KD.

CONCLUSION48 KD and 18 KD proteins play a role in metal resistance mechanism by NiRBI.

Biodegradation, Environmental ; Electrophoresis, Polyacrylamide Gel ; Gram-Negative Bacteria ; genetics ; growth & development ; metabolism ; Kinetics ; Nickel ; metabolism ; Phylogeny ; RNA, Ribosomal, 16S ; classification ; genetics

BACKGROUND: Infection is a frequent complication in patients with chronic liver disease, mainly during the advanced stages. This study was performed to investigate the risk factors for infections in hospitalized patients with decompensated liver cirrhosis. METHODS: We analyzed 108 decompensated hospitalized cirrhotic patients (34 cases with infection and 117 cases without infection) without clinical evidence of infection at the time of admission and during initial 72 hours after admission. RESULTS: Univariate and multivariate analysis revealed that patients who developed an infection were more likely to have a lower serum albumin levels. Gram-negative bacterial strains were detected most frequently, in 13 of the 18 strains isolated. There was no significant difference in etiology of disease, Child-Pugh classification, cirrhotic complications including upper G-I bleeding, hepatocelluar caricnoma, invasive procedure, diabetus mellitus, admission to ICU, duration of admission, survival rate and various parameters related to liver and renal function between patients with infection and without infection. CONCLUSION: The present study indicates that decompensated cirrhotic patient with low serum albumin levels have a higher risk of developing a hospital acquired infection, especially by gram negative bacteria.
Classification ; Cross Infection ; Gram-Negative Bacteria ; Gram-Negative Bacterial Infections ; Hemorrhage ; Humans ; Liver Cirrhosis* ; Liver Diseases ; Liver* ; Multivariate Analysis ; Risk Factors* ; Serum Albumin ; Survival Rate