Toehold-Containing Three-Way Junction-Initiated Multiple Exponential Amplification and CRISPR/Cas14a Assistant Magnetic Separation Enhanced Visual Detection of Mycobacterium Tuberculosis.

Rapid and simple nucleic acid detection is significant for disease diagnosis and pathogen screening, especially under specific conditions. However, achieving highly sensitive and specific nucleic acid detection to meet the time and equipment demand remains technologically challenging. In this study, we proposed a magnetic separation enhanced colorimetry biosensor based on a toehold-containing three-way junction (TWJ) induced multiple isothermal exponential amplification and the CRISPR/Cas14a (C-TEC) biosensor. The TWJ template was designed as a Y-X-Y structure. In the presence of the target, the formation of toehold-containing TWJ complex induced primer extension, leading to the generation of amplified single-stranded DNA; this amplified DNA could then bind to either the free TWJ template for EXPAR reaction or the toehold of the TWJ complex for toehold-mediated strand displacement, thereby enabling the recycling of the target. The amplification products could trigger CRISPR/Cas14a for efficient trans-cleavage and release the magnetically bound gold nanoparticle probes for colorimetry detection. Using Mycobacterium tuberculosis 16S rDNA as the target, the proposed C-TEC could detect 16S rDNA down to 50 fM by the naked eye and 20.71 fM by UV-vis detector at 520 nm within 90 min under optimal conditions. We successfully applied this biosensor to clinical isolates of Mycobacterium tuberculosis. In addition, the C-TEC biosensor also showed feasibility for the detection of RNA viruses. In conclusion, the proposed C-TEC is a convenient, fast, and versatile platform for visual detection of pathogen DNA/RNA and has potential clinical applications.

Clinical characteristics and antibiotic resistance profile of invasive MRSA infections in newborn inpatients: a retrospective multicenter study from China.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) can cause invasive infections with significant mortality in neonates. This study aimed to analyze the clinical characteristics and antibiotic resistance profiles of invasive MRSA infections and determine risk factors associated with invasive MRSA infections in newborn inpatients. METHODS: This multicenter retrospective study of inpatients from eleven hospitals in the Infectious Diseases Surveillance of Pediatrics (ISPED) group of China was performed over a two-year period (2018-2019). Statistical significance was calculated by applying the χ2 test or by Fisher's exact test in the case of small sample sizes. RESULTS: A total 220 patients were included. Among included cases, 67 (30.45%) were invasive MRSA infections, including two deaths (2.99%), while 153 (69.55%) were noninvasive infections. The invasive infections of MRSA occurred at a median age of 8 days on admission, which was significantly younger compared to 19 days in noninvasive cases. Sepsis (86.6%) was the most common invasive infection, followed by pneumonia (7.4%), bone and joint infections (3.0%), central nervous system infection (1.5%), and peritonitis (1.5%). Congenital heart disease, low birth weight infant (<2500 g), but not preterm neonates, and bronchopulmonary dysplasia, were more commonly found in invasive MRSA infections. All these isolates were susceptible to vancomycin and linezolid and were resistant to penicillin. Additionally, 69.37% were resistant to erythromycin, 57.66% to clindamycin, 7.04% to levofloxacin, 4.62% to sulfamethoxazole-trimethoprim, 4.29% to minocycline, 1.33% to gentamicin, and 3.13% were intermediate to rifampin. CONCLUSION: Low age at admission (≤8 days), congenital heart disease, and low birth weight were associated with invasive MRSA infections in neonates, and no isolates resistant to vancomycin and linezolid were found. Determining these risks in suspected neonates may help identify patients with imminent invasive infections who may require intensive monitoring and therapy.

Antimicrobial resistance profile of methicillin-resistant Staphylococcus aureus isolates in children reported from the ISPED surveillance of bacterial resistance, 2016-2021.

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious threat to public health worldwide. In December 2015, the Infectious Disease Surveillance of Pediatrics (ISPED) program was organized to monitor bacterial epidemiology and resistance trends in children. Methods: This retrospective study was conducted from January 2016-December 2021 on patients at eleven ISPED-group hospitals. Results: From 2016-2021, a total of 13024 MRSA isolates were obtained from children. The most common age group for patients with MRSA infection was less than 3 years old, and newborns were an important group affected by MRSA infection. MRSA was most commonly isolated from the lower respiratory, an abscess, a secretion, or blood in neonates and from the lower respiratory, an abscess, or the upper respiratory in non-neonates. All isolates were susceptible to vancomycin and linezolid and resistant to penicillin; additionally, 76.88%, 54.97%, 22.30%, 5.67%, 5.14%, 3.63%, and 1.42% were resistant to erythromycin, clindamycin, tetracycline, levofloxacin, sulfamethoxazole-trimethoprim (TMP-SMX), gentamicin, and rifampin, respectively. Between 2016 and 2021, a significant increase was seen in the levofloxacin- and TMP-SMX-resistance rates (from 5.45% to 7.14% and from 4.67% to 6.50%, respectively) among MRSA isolates, along with a significant decrease in the rates of resistance to erythromycin (from 82.61% to 68.08%), clindamycin (from 60.95% to 46.82%), tetracycline (from 25.37% to 17.13%), gentamicin (from 4.53% to 2.82%), and rifampin (from 1.89% to 0.41%). Discussion: The antibiotic-resistance rates varied among MRSA isolated from different sources. Because of the high antibiotic resistance rate to clindamycin, this antibiotic is not recommended for empirical treatment of MRSA infections, especially in osteomyelitis.

Drug Repurposing by Siderophore Conjugation: Synthesis and Biological Evaluation of Siderophore-Methotrexate Conjugates as Antibiotics.

Drug repurposing is considered a promising strategy to fight antimicrobial resistance (AMR). Methotrexate (Mtx), a classical anticancer drug, could strongly inhibit bacterial dihydrofolate reductase (DHFR). However, its poor permeability into bacteria and potent human cytotoxicity make it unsuitable as an antibacterial. Herein, we reported the conjugation of Mtx with a siderophore to construct "Trojan horse" antibacterials. The most potent conjugate 8 with nanomolar minimum inhibitory concentration (MIC) values exhibited over 1.00×103 -fold improved activity against Gram-positive Streptococcus pneumoniae (S. pneumoniae) and Gram-negative Yersinia enterocolitica (Y. enterocolitica) compared with Mtx, while possessing 2.31×103 -fold reduced human cytotoxicity, resulting in 2.08×106 -fold improvements in the therapeutic index. This proof-of-principle study verifies that siderophore conjugation is an effective strategy for developing new antibacterials from anticancer drugs.

Bacterial Epidemiology and Antimicrobial Resistance Profiles in Children Reported by the ISPED Program in China, 2016 to 2020.

The Infectious Disease Surveillance of Pediatrics (ISPED) program was established in 2015 to monitor and analyze the trends of bacterial epidemiology and antimicrobial resistance (AMR) in children. Clinical bacterial isolates were collected from 11 tertiary care children's hospitals in China in 2016 to 2020. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer method or automated systems, with interpretation according to the Clinical and Laboratory Standards Institute 2019 breakpoints. A total of 288,377 isolates were collected, and the top 10 predominant bacteria were Escherichia coli, Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Streptococcus pyogenes, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Acinetobacter baumannii. In 2020, the coronavirus disease 2019 (COVID-19) pandemic year, we observed a significant reduction in the proportion of respiratory tract samples (from 56.9% to 44.0%). A comparable reduction was also seen in the primary bacteria mainly isolated from respiratory tract samples, including S. pneumoniae, H. influenzae, and S. pyogenes. Multidrug-resistant organisms (MDROs) in children were commonly observed and presented higher rates of drug resistance than sensitive strains. The proportions of carbapenem-resistant K. pneumoniae (CRKP), carbapenem-resistant A. baumannii (CRAB), carbapenem-resistant P. aeruginosa (CRPA), and methicillin-resistant S. aureus (MRSA) strains were 19.7%, 46.4%%, 12.8%, and 35.0%, respectively. The proportions of CRKP, CRAB, and CRPA strains all showed decreasing trends between 2015 and 2020. Carbapenem-resistant Enterobacteriaceae (CRE) and CRPA gradually decreased with age, while CRAB showed the opposite trend with age. Both CRE and CRPA pose potential threats to neonates. MDROs show very high levels of AMR and have become an urgent threat to children, suggesting that effective monitoring of AMR and antimicrobial stewardship among children in China are required. IMPORTANCE AMR, especially that involving multidrug-resistant organisms (MDROs), is recognized as a global threat to human health; AMR renders infections increasingly difficult to treat, constituting an enormous economic burden and producing tremendous negative impacts on patient morbidity and mortality rates. There are many surveillance programs in the world to address AMR profiles and MDRO prevalence in humans. However, published studies evaluating the overall AMR rates or MDRO distributions in children are very limited or are of mixed quality. In this study, we showed the bacterial epidemiology and resistance profiles of primary pathogens in Chinese children from 2016 to 2020 for the first time, analyzed MDRO distributions with time and with age, and described MDROs' potential threats to children, especially low-immunity neonates. Our study will be very useful to guide antiinfection therapy in Chinese children, as well as worldwide pediatric patients.

Antimicrobial resistance of Haemophilus influenzae isolates from pediatric hospitals in Mainland China: Report from the ISPED program, 2017-2019.

PURPOSE: This study set out to determine the antimicrobial resistance trends of Haemophilus influenzae isolates from pediatric hospitals in Mainland China, which would provide basis for clinical treatment. METHODS: The Infectious Disease Surveillance of Pediatrics (ISPED) collaboration group conducted this study. H. influenzae strains isolated from nine pediatric hospitals in Mainland China were included. Disk diffusion method was used for antimicrobial susceptibility test. Cefinase disc was used for detection of ß-lactamase. RESULTS: In total, 13810 H. influenzae isolates were included during 2017-2019: 93.17% of which were from respiratory tract specimens, 4.63% from vaginal swabs, 1.10% from secretion, and 1.10% from others. Of all strains, 63.32% isolates produced ß-lactamase; 8.22% isolates were ß-lactamase-negative and ampicillin-resistant (BLNAR). The resistance to sulfamethoxazole-trimethoprim was 70.98%, followed by resistance to ampicillin (69.37%), cefuroxime (51.35%), ampicillin-sulbactam (38.82%), azithromycin (38.21%), amoxicillin-clavulanate (35.28%). More than 90% of H. influenzae isolates were susceptible to ceftriaxone, cefotaxime, meropenem, levofloxacin and chloramphenicol. The resistance rate of ampicillin and azithromycin in H. influenzae showed an increasing trend through the years. Statistically significant differences in antibiotic-resistance rates of all the antibiotics except chloramphenicol were found in different regions. The major Multi-Drug Resistance pattern was resistant to ß-lactams, macrolides, and sulfonamides. CONCLUSIONS: There is a rising trend of resistance rate of ampicillin and azithromycin in H. influenzae. Antimicrobial resistance of H. influenzae deserves our ongoing attention. Third-generation cephalosporin could be the preferred treatment option of infections caused by ampicillin-resistant H. influenzae.

Progranulin Mediates Proinflammatory Responses in Systemic Lupus Erythematosus: Implications for the Pathogenesis of Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease caused by the disorders of immune regulation but its pathogenesis is poorly understood. Progranulin (PGRN) is an immunomodulatory protein that is upregulated in SLE patients. However, the factors involved in regulating the pathogenesis of SLE by PGRN are largely unknown. We sought to investigate the role and molecular mechanisms of PGRN in SLE to develop a novel therapeutic target. We used an animal model of SLE that was induced in PGRN-deficient and normal wild type (WT) mice using pristane. PGRN concentrations were measured in SLE and the impact of PGRN deficiency was examined by measuring tissue injury and immune responses of T cells (Th1, Th2, Th17, and Treg) and B cells. SLE patients and mice showed elevated PGRN levels. Compared with WT SLE mice, inflammatory cell infiltration, tissue edema, and necrosis were alleviated in PGRN-/- SLE mice and the levels of serum chemistry markers of tissue damage and the presence of anti-double-stranded DNA and anti-ribosomal protein P0 antibodies were all significantly decreased. We further discovered that PGRN deficiency could disturb the immune responses of T cell (Th1, Th2, Th17, and Treg) and B cell responses, leading to the decrease of inflammatory cytokines including interferon-γ and interleukin-17A and increased levels of regulatory B cells. PGRN plays a proinflammatory role in the development of SLE partially through promoting the production of autoantibodies and enhancing Th1 and Th17 cell responses. This may provide new therapeutic options for patients with SLE.

Molecular epidemiology and antimicrobial resistance of invasive non-typhoidal Salmonella in China, 2007-2016.

PURPOSE: Human infections caused by invasive non-typhoidal Salmonella (iNTS) are highly prevalent worldwide. However, data for such infections in China are scarce. This study reports the epidemiology of iNTS in China. METHODS: INTS isolates were recovered from blood and other clinical specimens collected during 2007-2016 across five provinces (Shanghai, Xinjiang, Fujian, Guangxi, and Chongqing) in China. Antimicrobial susceptibility was performed using the agar dilution method and molecular epidemiology was performed using standard microbiological techniques. RESULTS: A total of 178 iNTS isolates were recovered from approximately 9700 patient specimens during 2007-2016. The predominant serovars were Salmonella Enteritidis (57/178, 32%), Salmonella Choleraesuis (47/178, 26.4%), and Salmonella Typhimurium (24/178, 13.5%). Up to 50 isolates (28.1%) were from patients who were ≤1 year of age, while 28 (15.7%) were from patients who were ≥60 years. Among these isolates, high rates of resistance to nalidixic acid (114/178, 64%), sulfisoxazole (59%), ciprofloxacin (15.2%), and cefotaxime (8.4%) were found. Moreover, 53.4% (95/178) exhibited multidrug resistance, and 3.9% (7/178) showed co-resistance to third-generation cephalosporins and ciprofloxacin. Steadily increasing numbers of nalidixic acid, cefotaxime, and ciprofloxacin-resistant isolates, but decreasing numbers of multidrug resistance isolates were detected during the study period. Detection of quinolone genes in 114 nalidixic acid-resistant isolates showed that 58.3% (67/114) harbored plasmid-mediated quinolone resistance (PMQR) genes [aac(6´)-Ib-cr, qnrA, qnrB, oqxAB, qepA, qnrS, and qnrD] and 98.2% (112/114) exhibited mutations in quinolone resistance determining regions [gyrA, parC, and parE]. Furthermore, we detected beta-lactamases genes in the ceftriaxone-resistant isolates. The most common were blaTEM-1 (93.3%), followed by blaCTX-M-55 (40%), blaCMY-2 (33.3%), and blaOXA-1 (33.3%). Finally, a range of pulsed-field gel electrophoresis patterns were detected among the Salmonella Enteritidis and Salmonella Typhimurium isolates. CONCLUSION: High rates of multidrug resistance and steadily increasing cefotaxime and ciprofloxacin-resistant iNTS could pose a significant challenge for the effective treatment of salmonellosis in China.

[Clinical characteristics and drug sensitivity in children with invasive pneumococcal disease: a multicenter study].

OBJECTIVE: To study the clinical characteristics, drug sensitivity of isolated strains, and risk factors of drug resistance in children with invasive pneumococcal disease (IPD). METHODS: The clinical characteristics and drug sensitivity of the isolated strains of 246 hospitalized children with IPD in nine grade A tertiary children's hospitals from January 2016 to June 2018 were analyzed. RESULTS: Of the 246 children with IPD, there were 122 males and 124 females. Their ages ranged from 1 day to 14 years, and among them, 68 (27.6%) patients were less than 1 year old, 54 (22.0%) patients were 1 to 2 years old, 97 (39.4%) patients were 2 to 5 years old, and 27 (11.0%) patients were 5 to 14 years old. Pneumonia with sepsis was the most common infection type (58.5%, 144/246), followed by bloodstream infection without focus (19.9%, 49/246) and meningitis (15.0%, 37/246). Forty-nine (19.9%) patients had underlying diseases, and 160 (65.0%) had various risk factors for drug resistance. The isolated Streptococcus pneumoniae strains were 100% sensitive to vancomycin, linezolid, moxifloxacin, and levofloxacin, 90% sensitive to ertapenem, ofloxacin, and ceftriaxone, but had a low sensitivity to erythromycin (4.2%), clindamycin (7.9%), and tetracycline (6.3%). CONCLUSIONS: IPD is more common in children under 5 years old, especially in those under 2 years old. Some children with IPD have underlying diseases, and most of the patients have various risk factors for drug resistance. Pneumonia with sepsis is the most common infection type. The isolated Streptococcus pneumoniae strains are highly sensitive to vancomycin, linezolid, moxifloxacin, levofloxacin, ertapenem, and ceftriaxone in children with IPD.

Antibiotic resistance profiles and multidrug resistance patterns of Streptococcus pneumoniae in pediatrics: A multicenter retrospective study in mainland China.

Emergent resistance to antibiotics among Streptococcus pneumoniae isolates is a severe problem worldwide. Antibiotic resistance profiles for S pneumoniae isolates identified from pediatric patients in mainland China remains to be established.The clinical features, antimicrobial resistance, and multidrug resistance patterns of S pneumoniae were retrospectively analyzed at 10 children's hospitals in mainland China in 2016.Among the collected 6132 S pneumoniae isolates, pneumococcal diseases mainly occurred in children younger than 5 years old (85.1%). The resistance rate of S pneumoniae to clindamycin, erythromycin, tetracycline, and trimethoprim/sulfamethoxazole was 95.8%, 95.2%, 93.6%, and 66.7%, respectively. The resistance rates of S pneumoniae to penicillin were 86.9% and 1.4% in non-meningitis and meningitis isolates, while the proportions of ceftriaxone resistance were 8.2% and 18.1%, respectively. Pneumococcal conjugate vaccine was administered to only 4.1% of patients. Penicillin and ceftriaxone resistance, underling diseases, antibiotic resistant risk factors, and poor prognosis appeared more frequently in invasive pneumococcal diseases. The incidence of multidrug resistance (MDR) was 46.1% in patients with invasive pneumococcal disease which was more than in patients with non-invasive pneumococcal disease (18.3%). Patients with invasive pneumococcal disease usually have several MDR coexistence.S pneumoniae isolates showed high resistance to common antibiotics in mainland China. Penicillin and ceftriaxone resistance rate of invasive streptococcal pneumonia patients were significantly higher than that of non-invasive S pneumoniae patients. Alarmingly, 46.1% of invasive clinical isolates were multidrug resistant, so it is important to continued monitor the resistance of S pneumoniae when protein conjugate vaccine (PCV13) is coming in mainland China.

A multi-center clinical investigation on invasive Streptococcus pyogenes infection in China, 2010-2017.

BACKGROUND: Invasive S. pyogenes diseases are uncommon, serious infections with high case fatality rates (CFR). There are few publications on this subject in the field of pediatrics. This study aimed at characterizing clinical and laboratory aspects of this disease in Chinese children. PATIENTS AND METHODS: A retrospective study was conducted and pediatric in-patients with S. pyogenes infection identified by cultures from normally sterile sites were included, who were diagnosed and treated in 9 tertiary hospitals during 2010-2017. RESULTS: A total of 66 cases were identified, in which 37 (56.1%) were male. The median age of these patients, including 11 neonates, was 3.0 y. Fifty-nine (89.4%) isolates were determined from blood. Fever was the major symptom (60/66, 90.9%) and sepsis was the most frequent presentation (64/66, 97.0%, including 42.4% with skin or soft tissue infections and 25.8% with pneumonia. The mean duration of the chief complaint was (3.8 ± 3.2) d. Only 18 (27.3%) patients had been given antibiotics prior to the hospitalization. Among all patients, 15 (22.7%) developed streptococcal toxin shock syndrome (STSS). No S. pyogenes strain was resistant to penicillin, ceftriaxone, or vancomycin, while 88.9% (56/63) and 81.4% (48/59) of the tested isolates were resistant to clindamycin and erythromycin respectively. Most of the patients were treated with ß-lactams antibiotics and 36.4% had been treated with meropenem or imipenem. Thirteen (19.7%) cases died from infection, in which 9 (13.6%) had complication with STSS. CONCLUSIONS: Invasive S. pyogenes infections often developed from skin or soft tissue infection and STSS was the main cause of death in Chinese children. Ongoing surveillance is required to gain a greater understanding of this disease.

Total synthesis and antimicrobial evaluation of natural albomycins against clinical pathogens.

Development of effective antimicrobial agents continues to be a great challenge, particularly due to the increasing resistance of superbugs and frequent hospital breakouts. There is an urgent need for more potent and safer antibiotics with novel scaffolds. As historically many commercial drugs were derived from natural products, discovery of antimicrobial agents from complex natural product structures still holds a great promise. Herein, we report the total synthesis of natural albomycins δ1 (1a), δ2 (1b), and ε (1c), which validates the structures of these peptidylnucleoside compounds and allows for synthetic access to bioactive albomycin analogs. The efficient synthesis of albomycins enables extensive evaluations of these natural products against model bacteria and clinical pathogens. Albomycin δ2 has the potential to be developed into an antibacterial drug to treat Streptococcus pneumoniae and Staphylococcus aureus infections.

Minimal inhibitory concentration drift of glycopeptides and linezolid against S. Aureus at a Chinese children's center, 2009-2013.

We analyzed the drift in the minimum inhibitory concentration (MIC) of glycopeptides and linezolid against 793 methicillin-resistant Staphylococcus aureus (MRSA) and 4696 methicillin-susceptible S. aureus (MSSA) isolates from Chinese children. For vancomycin and teicoplanin, no significant change occurred in different years for MIC values ≥ 2 µg/mL, either in MRSA or MSSA. For linezolid, there was an MIC drift in MRSA and in MSSA.

[Clinical analysis of 22 cases community-acquired Pseudomonas aeruginosa urinary tract infection].

OBJECTIVE: To study the characteristics of community-acquired urinary tract infections (CAUTIs) in children, analyze the risk factors and the susceptibility of antibiotics, thus to provide references to the diagnosis and medication of Pseudomonas aeruginosa (PA)-CAUTIs. Mothod Totally 22 cases of PA-CAUTIs were selected in one hospital from Jan, 2006 to Jan, 2012, their clinical information, laboratory results and radiological images were collected, and were compared with the CAUTIs cased by E. coli of those randomly selected over the same period. RESULT: In those 22 cases with PA-CAUTIs, the mean value of protein level was (32.25 ± 13.81) mg/ml, 19 of them were hospitalized, 6 had urinary operation history, 7 of them had long-term usage of glucocorticoids or immunosuppressive agents, and 20 had underlying diseases. A total of 22 children with 26 PA-CAUTIs episodes were compared to E. coli-CAUTIs. Compared with E. coli-CAUTIs patients, children with PA-CAUTIs more often presented with a lower albumin (P = 0.017), a history of urinary operation(P = 0.03), more cases had a history of urinary operation (P = 0.03), a long-term usage of glucocorticoids or immunosuppressive medication (P = 0.044). Through multivariate logistic regression of variables that were significant in univariate analysis (with hospitalizations, long-term usage of glucocorticoids or immunosuppressive, albumin, underlying disease and urinary operation histories), and it turned out that underlying diseases (odds ratio 8.500, 95% CI 1.513 - 47.761, P = 0.037) and with urinary operation histories (odds ratio 6.196, 95% CI 1.120 - 34.273, P = 0.037) were proved as the independent risk factors for PA-CAUTIs. Those PA bacterial strains had a 36.36% resistance rate to piperacillin, aztreonam and gentamicin, a 31.82% resistance rate to cefepime and ceftazidime, while the resistance rate (4.55%) to carbapenem antibiotics was relatively low, only to bacillosporin all the strains were sensitive. CONCLUSION: Underlying diseases and the urinary operation histories are the independent risk factors of the occurrence of PA-CAUTIs, carbapenem antibiotics and bacillosporin can be considered as the drugs of choice for its treatment.

[Effects of Pseudomonas quinolone signal on the virulence of Pseudomonas aeruginosa].

OBJECTIVE: To investigate the effect of Pseudomonas quinolone signal (PQS) on the virulence of Pseudomonas aeruginosa. METHODS: Pseudomonas aeruginosa strain PAO1 was treated with PQS alone, PQS plus farnesol, or farnesol alone. The transcriptional levels of the regulator gene ExsA and virulence protein gene ExoS of type III secretion system were examined using quantitative real-time PCR, and spectrophotometry was employed to detect pyocyanin production in the bacteria. The adhesion and invasiveness of the treated PAO1 in cultured alveolar epithelial cells A549 were assessed on plate count agar, and their effects on the survival of a mouse model of peritonitis was compared. RESULTS: The increase or decrease of PQS did not affect the growth of PAO1. Compared with the untreated bacteria, PQS-treated PAO1 showed obviously increased transcription levels of ExsA and ExoS (P<0.01) and pyocyanin production, which was significantly lowered by farnesol (P<0.01). In A549 cell cultures, farnesol-treated PAO1 exhibited significantly lowered adhesion and invasiveness, while PQS-treated PAO1 caused a significantly decreased survival time of mice with peritonitis (P<0.01). Farnesol treatment did not obviously affected ExsA transcription (P>0.05) but caused a significant reduction in the transcriptional level of Exos (P<0.05) in PAO1. PQS showed no significant effect on the adhesion and invasiveness of PAO1 (P<0.05). CONCLUSION: PQS can maintain the adhesion and invasiveness of Pseudomonas aeruginosa, and in the hosts of the bacteria, PQS concentration is positively correlated with pyocyanin production and hence negatively with the survival time of the hosts.

Antibiotic resistance and molecular epidemiology of the beta-lactamase-producing Haemophilus influenzae isolated in Chongqing, China.

This study aimed to determine the antibiotic resistance and molecular epidemiology of Haemophilus influenzae isolated from children with acute respiratory infection in Chongqing, China. To this end, 1967 H. influenzae isolates from 2006 to 2009 were analysed regarding ß-lactamase production and antibiotic resistance. Ninety-nine ß-lactamase-producing H. influenzae isolates from 2010 were analysed for antibiotic resistance and promoter regions of bla(TEM) (-1) . ß-lactamase production was found in 35.8% (705/1967) of the strains. All ninety-nine ß-lactamase-producing strains from 2010 were of the TEM-1 type as determined by PCR but did not produce the predicted 1075 bp product. According to PCR-SSCP and DNA sequencing, the promoter regions of bla(TEM) (-1) were categorized into 6 genotypes as SSCP1 (Pdel), SSCP2 (Pa/Pb), SSCP3 (P4), SSCP4 (Prpt.b), SSCP5 (2Prpt) and SSCP6 (P3.b). The Pdel, Pa/Pb and Prpt.b were common promoters of bla(TEM) (-1) for H. influenzae isolated from children in Chongqing. Strains with Prpt.b were more resistant to ampicillin (AMP) than strains with Pdel, Pa/Pb and P4 (p < 0.05). Therefore, bla(TEM-1) ß-lactamase is the main mechanism for resistance of H. influenzae to ampicillin in Chongqing. Furthermore, the Prpt.b promoters may be related to the high resistance of H. influenzae to AMP.