中药在控制耐药菌Acinetobacter baumannii繁殖中的研究进展

鲍曼不动杆菌存在多重耐药性,感染后可选择抗菌药物有限,病死率高,抗鲍曼不动杆菌感染是目前临床研究领域的重点和难点。部分中药表现出抑制鲍曼不动杆菌生长的作用,但是其抗菌机制尚不清楚。基于此,本文系统综述了近年来中草药在控制鲍曼不动杆菌感染方面的研究进展,以期为中药抗菌药物的研发提供依据。

Prevalence and Antibiotic Resistance of Urinary Tract Pathogens, with Molecular Identification of Klebsiella pneumoniae, Klebsiella oxytoca, and Acinetobacter spp., Using Multiplex Real-Time PCR

Urinary tract infections (UTIs) caused by uropathogens are a significant public health problem, and their treatment primarily relies on antibiotic therapy. However, the increasing global development of antibiotic resistance necessitates updating diagnostic techniques to ensure higher sensitivity and specificity, especially with advancements in science and medicine. This study aimed to evaluate the prevalence of UTIs and antibiotic resistance profiles through urine culture, as well as to identify Klebsiella pneumoniae, Klebsiella oxytoca, and Acinetobacter spp. in urine samples using a molecular approach with multiplex real-time PCR. From May 3 to July 25, 2023, at the Pietro Annigoni Biomolecular Research Center (CERBA) and Saint Camille Hospital of Ouagadougou (HOSCO), 209 urine samples collected from patients with suspected UTIs were analyzed using both urine culture and multiplex real-time PCR. Among the 209 patients, 52.15% were male and 47.85% female, with an average age of 46.87 ± 21.33 years. Urine cultures revealed an overall UTI prevalence of 23.44%, with a prevalence of 8.13% in men versus 15.31% in women (P = 0.023). The bacterial prevalence rates were as follows: Escherichia coli (12.92%), Klebsiella spp. (7.18%), Enterobacter cloacae (1.44%), Staphylococcus aureus (0.96%), and other bacteria. Klebsiella spp. demonstrated 100% resistance to Amoxicillin and Amoxicillin/Clavulanic Acid, while Escherichia coli showed 96.2% and 65.4% resistance to Amoxicillin and Amoxicillin/Clavulanic Acid, respectively. PCR analysis of the target bacteria revealed mono-infection prevalence rates of Klebsiella pneumoniae (10.39%), Klebsiella oxytoca (7.79%), and Acinetobacter spp. (7.79%), along with a co-infection prevalence rate of Klebsiella pneumoniae/Acinetobacter spp. (1.30%). This study demonstrated that PCR, with its high sensitivity and specificity, could effectively distinguish Klebsiella pneumoniae from Klebsiella oxytoca and detect Acinetobacter spp. in less than 24 hours—something urine culture alone could not achieve. The relative ease of automating urine PCR testing, combined with its diagnostic accuracy and rapid turnaround time, makes it a valuable addition to modern medical practice for the laboratory diagnosis of UTIs.

Dissemination of carbapenem-non-susceptible Acinetobacter baumannii isolates collected from educational hospitals in Qazvin province of Iran

Background:Acinetobacter baumannii(A.baumannii)is known as an opportunistic pathogen related to health-care-associated infection that has a high antibiotic resistance potential,notably against carbapenems that are widely used to combat A.baumannii infections.This study aimed to detect oxacillin-hydrolyzing(OXA)carbapenemases and metallo-β-lactamases(MBL)among carbapenem-resistant A.baumannii isolated strains and to determine their clonal relationship by repetitive extragenic palindromic PCR(rep-PCR).Methods:In the present study,a total of 211 non-repetitive isolates of A.baumannii were collected from Qazvin educational hospitals(2016–2017).The disk diffusion method was used to investigate the antibiotic susceptibility of studied strains,followed by the detection of MBL and OXA-type genes using polymerase chain reaction(PCR)and sequencing methods.The rep-PCR method assessed the clonal relationship of carbapenem-non-susceptible A.baumannii isolates.Result:The obtained results showed that 87.2%and 86.7%of isolates were non-susceptible to imipenem and meropenem.The blaOXA-24(93.5%)was the most frequent gene,followed by the blaOXA-23(4.34%),blaIMP-1(1.63%),and blaVIM-1(0.54%).Meanwhile,blaOXA-58 and blaOXA-143 genes were not found.81.5%and 66.1%of isolates contained ISAba1 upstream of the blaOXA-23 and blaOXA-58 genes,respectively.Rep-PCR results revealed the carbapenem non-susceptible isolates belonged to three distinct clones:A 171(81%),B 34(16.1%),and C 6(2.8%).Conclusions:The results indicated a high prevalence of carbapenem-non-susceptible A.baumannii,with the emergence of the blaOXA-24 gene as the most common gene and the notable prevalence of MBL genes.These results revealed the need for appropriate therapeutic and infection control strategies and monitoring susceptibility patterns for controlling A.baumannii infections.

Occurrence of K1 and K2 serotypes and genotypic characteristics of extended spectrumβ-lactamases-producing Klebsiella pneumoniae isolated from selected hospitals in Malaysia

Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selected hospitals in Malaysia.Methods:A total of 192 K.pneumoniae isolates were collected and subjected to antibiotic susceptibility,hypermucoviscosity test and multiplex PCR to detect the presence of K1-and K2-serotype associated genes.Multilocus sequence typing(MLST)was performed on ESBL-producing K.pneumoniae isolates presented with K1 and K2 serotypes,followed by phylogenetic analysis.Results:A total of 87 out of 192(45.3%)of the K.pneumoniae isolates collected were ESBL producers.However,only 8.3%(16/192)and 10.9%(21/192)of the total isolates were detected to carry K1-and K2-serotype associated genes,respectively.Statistical analysis showed that K1 and K2 capsular serotypes were not significantly associated with ESBL phenotype(P=0.196).However,they were significantly associated with hypervirulent,as demonstrated by the positive string test(P<0.001).MLST analysis revealed that ST23 as the predominant sequence type(ST)in the K1 serotype,while the ST in the K2 serotype is more diverse.Conclusions:Although the occurrence of ESBL-producing isolates among the hypervirulent strains was low,their coexistence warrants the need for continuous surveillance.MLST showed that these isolates were genetically heterogeneous.

Epidemiology of carbapenem-resistant Acinetobacter baumannii colonization in neonatal intensive care units:A systematic review and meta-analysis

BACKGROUND The rising prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)in neonatal intensive care units(NICUs)represents an escalating challenge in healthcare settings,particularly in managing hospital-acquired infections(HAIs).Studies across various World Health Organization regions have documented a significant incidence of CRAB-related HAIs,with rates as high as 41.7 cases per 1000 patients in ICUs,accounting for 13.6%of all HAIs.These infections pose a doubled mortality risk compared to infections with carbapenem-susceptible Acinetobacter baumannii.A particularly concerning aspect of CRAB colonization is its asymptomatic nature,enabling its transmission through healthcare workers(HCWs)or the NICU environment to vulnerable neonates with developing immune systems.AIM To explore the prevalence of CRAB colonization in NICUs,focusing on neonates,healthcare workers,and the environmental samples,to enhance epidemiological understanding and inform targeted interventions.METHODS We conducted according to PRISMA 2020 checklist guidelines,a comprehensive literature search across multiple databases including MEDLINE(Ovid),EMBASE(Ovid),Global Health(Ovid),Web of Science,and Global Index Me-dicus.Studies were selected based on predetermined criteria,primarily involving neonates,HCWs,and environmental swabs,using culture or molecular methods to detect CRAB colonization.We excluded studies that did not specifically focus on NICUs,were duplicates,or lacked necessary data.The study selection and quality assessment were conducted independently by two reviewers.Data extraction involved collecting comprehensive details about each study.Our statistical analysis used a random-effects model to calculate the pooled prevalence and confidence intervals,stratifying results by regional location.We assessed study heterogeneity using Cochran's Q statistic and I²statistic,with regression tests employed to evaluate potential publication bias.RESULTS We analyzed 737 records from five databases,ultimately including 13 studies from ten countries.For neonates,the pooled prevalence was 4.8%(95%CI:1.1%to 10.5%)with the highest rates observed in South-East Asia(10.5%;95%CI:2.4%to 23.3%).Among HCWs,a single Indian study reported a 3.3%prevalence.Environmental samples showed a prevalence of 2.3%(95%CI:0%to 9.3%),with the highest rates in South-East Asia(10%;95%CI:4.2%to 17.7%).Significant heterogeneity was found across studies,and no publication bias was detected.CONCLUSION This systematic review highlights a significant prevalence of CRAB colonization in neonates across various regions,particularly in South-East Asia,contrasting with lower rates in high-income countries.The study reveals a gap in research on HCWs colonization,with only a single study from India reporting moderate prevalence.Environmental samples indicate moderate levels of CRAB contamination,again higher in South-East Asia.These findings underscore the need for more extensive and focused research on CRAB colonization in NICUs,including exploring the roles of HCWs and the environment in transmission,understanding antimicrobial resistance patterns,and developing effective prevention measures.

Clinical Efficacy and Safety Analysis of Tigecycline in the Treatment of Acute Exacerbation of Chronic Obstructive Pulmonary Disease Combined with Multidrug-Resistant Acinetobacter baumannii Infection

Objective:To study the clinical efficacy and safety of tigecycline in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD)combined with multidrug-resistant Acinetobacter baumannii infection.Methods:113 patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection were recruited between January 2021 and January 2023,and given tigecycline treatment.The total effective rate,lung function indexes,related biochemical index levels,and the incidence rate of adverse reactions were observed after the treatment.Results:After the treatment,100 patients were cured,1 case with apparent effect,2 cases were effective,10 cases were ineffective,and the total effective rate was 91.15%.The post-treatment CRP(21.22±3.35 mg/L),PCT(3.18±1.11 ng/L),CRE(76.36±9.24μmol/L),and ALT(37.76±6.99 U/L)were significantly improved as compared to the pre-treatment(P<0.05).After treatment,10 cases of vomiting(8.85%),13 cases of nausea(11.50%),4 cases of diarrhea(3.53%),1 case of abdominal pain(0.88%),and 2 cases of allergy(1.77%)were observed in 113 patients.Conclusion:Tigecycline therapy for patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection not only has significant therapeutic efficacy but also has a high degree of safety.

菌株Acinetobacter sp. Z1低温脱氮除磷性能及氮磷转化途径

从冬季污水处理厂活性污泥中筛选出一株在低温及好氧条件下具有脱氮除磷功能的菌株,经16Sr DNA序列分析鉴定为不动杆菌,命名为Acinetobactersp.Z1.在10℃条件下探究菌株Z1的脱氮除磷性能及氮磷转化途径.结果表明,菌株Z1能够利用NH4+-N或NO3--N为唯一氮源,以及NH4+-N和NO3--N为混合氮源进行脱氮除磷.菌株Z1在碳源为乙酸钠,m(COD)/m(N)≥20,m(P)/m(N)=0.2,中性或弱碱性溶液中,摇床转速n≥100r/min的条件下具有良好的氮磷去除效果,NH4+-N和PO43--P最大去除率可分别达96.0%和97.9%.菌株Z1的氮转化途径主要是同化,同时也能通过异养硝化-好氧反硝化作用脱氮.菌株Z1可以在好氧条件下除磷,在厌氧条件下不释放磷.实验结果表明菌株Z1在低温条件下具有良好的脱氮除磷能力,在冬季污水生物处理中有良好的应用前景.

几丁质降解菌Acinetobacter sp.WML1的生物安全性和发酵优化

Acinetobacter sp.WML1分离自淡水湖渔场沉积物,能降解几丁质,具有一定的应用价值。为了评价菌株WML1的生物安全性,为菌株的安全使用提供参考和保障,采用常规纸片扩散法检测耐药性,用血琼脂平板划线法检测溶血性,用溴甲酚紫显色法检测氨基酸脱羧酶活性,用试剂盒测定硝酸还原酶活性。在菌株生物安全性分析的基础上,通过单因素试验法和正交试验法进行菌株WML1产几丁质酶发酵条件的优化。结果表明,菌株WML1对多种抗生素敏感,无溶血性,无硝酸还原酶活性,有精氨酸脱羧酶活性及微弱的赖氨酸和鸟氨酸脱羧酶活性;其最优产酶条件为0.4%黄豆粉、0.20%半乳糖、0.03%KH2PO4、0.07%K2HPO4、0.002%FeSO_(4)、0.05%Mg SO_(4)·7H2O、0.001%ZnSO_(4)、0.60%胶体几丁质、pH 9.5、5.0%的接种量、25 m L的装液量(对应250 m L容量瓶)、37℃的培养温度,优化后的几丁质酶活为(2.72±0.09)U/m L。综上所述,不动杆菌WML1在使用安全性上危害较小,可防可控,经发酵条件优化后其所产几丁质酶的活性提高了约4.61倍,为产几丁质酶菌株的工业化应用提供了理论基础。

Study on Distribution of Acinetobacter baumannii Complex in Dental Hospital Using Multiplex PCR

Purpose: In recent years, multidrug-resistant Acinetobacter baumannii has appeared and caused outbreaks of hospital infections all over the world. Close monitoring of this pathogen and other A. baumanii complex species is considered of critical importance to public health organizations. The reliable identification method able to distinguish A. baumannii from genetically close Acinetobacter species is needed, because these species are unable to be differentiated by phenotypic or biochemical methods. The purpose of the present study was to design species-specific primers in order to identify and detect A. baumanii complex species, and Acinetobacter lwoffii which is frequently detected from the human specimens, and to investigate the distribution of these organisms in dental hospital using a multiplex PCR. Methods: Polymerase chain reaction (PCR) primers were designed based on partial sequences of the 16S ribosomal RNA (16S rRNA) gene and DNA gyrase subunit B (gyrB) of each species of A. baumanii complex species. Swab samples were collected from ten dental spittoon units in dental hospital, and the distribution of A. baumanii complex species was investigated using a multiplex PCR. Results: These primers were able to distinguish each species of A. baumanii complex species clearly. A. baumanii and A. calcoaceticus were detected at 20.0% and 10.0% in ten swab samples, respectively. On the other hand, A. nosocomialis, A. lowffii, and A. pittii were detected from no sample. Conclusion: Our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and worked without requiring DNA extraction.

Colistin Resistance Profiles, Molecular Investigation of mcr-1 and mcr-2 Plasmid Genes and Investigation of Carbapenemase Production in Pseudomonas and Acinetobacter Strains

Background and Purpose: The reintroduction of colistin as a last resort treatment against multi-resistant Gram-negative bacilli, is currently challenged by the emergence of colistin-resistant bacteria. The aim of this study was to assess the susceptibility of Pseudomonas and Acinetobacter strains to colistin, to identify carbapenemase production, and to investigate the plasmid genes involved in colistin resistance and carbapenemase production. Methodology: In order to establish the susceptibility profiles of 17 strains of Pseudomonas and Acinetobacter to colistin, their Minimum Inhibitory Concentrations (MICs) were determined using the liquid microdilution method. The possible production of carbapenemases was investigated with the modified Carbapenem Inactivation Method (mCIM). The search for genes encoding carbapenemases (blaOXA, blaIMP, blaCarba) and those responsible for plasmid resistance to colistin (mcr-1 and mcr-2) was performed by conventional PCR. Results and Conclusion: Ninety-four percent (94%) (16/17) of the strains were resistant to colistin. Intraspecies distribution was 50% (8/16), 31% (5/16), 13% (2/16) and 6% (1/16) for Acinetobacter baumannii, Pseudomonas aeruginosa, Pseudomonas luteola, and Pseudomonas fluorescens, respectively. Twenty-nine percent (29%) (6/17) of the strains produced carbapenemases. No mcr-1 and mcr-2 plasmid genes were detected. On the other hand, 17.6% (3/17) of the strains possessed the carbapenemase genes distributed as follows: Carba type (60%), OXA type (40%) and IMP type (0%). The results of this study highlight a high resistance to colistin in strains belonging to the genera Acinetobacter and Pseudomonas, and some of these strains produce carbapenemases.

Phenotypic Characterization and Prevalence of Carbapenemase-Producing Acinetobacter baumanii Isolates in Four Health Facilities in Cameroon

Background and Objective: Nowadays, the clinical utility of carbapenems is threatened by the emergence of resistant bacteria, favored by its increasing use. According to the WHO, Acinetobacter baumannii: nosocomial infection agent, tops the list of priority antibiotic-resistant pathogens, considered to be the riskiest for humans. This study sought to determine the prevalence of carbapenemase-producing Acinetobacter baumannii strains in four health facilities in the Center and Littoral regions of Cameroon and the associated risk factors. Materials and Method: An analytical cross-sectional study was conducted over a six-month period from January to June 2022. All suspicious A. baumanii isolates obtained from pathological samples at the bacteriology laboratory of the different health facilities were systematically collected and re-identified. Re-identification and antimicrobial susceptibility Testing (AST) were performed using the VITEK 2 System and the Kirby-Bauer method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Detection and phenotypic characterization of carbapenemases was performed according to adequate standard procedures. Results: A total of 168/226 clinical isolates of Acinetobacter baumannii were confirmed after re-identification, among which 52.69% derived from male patients, 55.09% from participants aged between 10 - 39 years old, and 46.71% from pus samples. A very high resistance rates to all families of antibiotics was noted, except to colistin (10.2%). 40.12% of these isolates produced carbapenemase, represented by 62.69% of class B and 37.31% of class A. Carbapenemase production was observed only at HMR1, Centre region and at Laquintinie hospital, Littoral region with 53.33% and 50% respectively, even if there is no significant difference (P = 0.81). In addition, frequent hospitalisation was significantly associated to the production of carbapenemase among A. baumanii (Adjusted-OR = 16.53, P-value 0.0001). Conclusion: This study highlighted the emergence of carbapenemase-producing Acinetobacter baumannii which is increasingly growing. Continuous drug-resistant monitoring and preventive measures could help to prevent and curb the dissemination of A. baumanii resistance genes, especially in health settings.

Risk Factors Associated with MDR and CR Acinetobacter baumannii Carriage among ICU Patients Hospitalized at MOI Teaching and Referral Hospital, Kenya

Background: Multi-drug resistant and Carbapenem-Resistant Acinetobacter baumannii (CRAB) infections present a significant challenge in hospital ICU settings worldwide and the threat posed is worse in developing countries including Kenya. Despite the limited treatment options, there is inadequate comprehensive data on factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at hospitals. This study therefore aimed to address this gap and determined risk factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at MOI Teaching and Referral Hospital, Kenya. Methods: Through cross-sectional study design, a total of 132 ICU admitted patients were purposively enrolled in this study between July 2019 and July 2020. Demographic and risk factors associated with MDR and CR Acinobacter baumannii were collected using structured questionnaire. Descriptive statistics and bivalent analysis were used for data analysis obtained. Level of statistical significance was 95% confidence interval (CI) for all analysis. Results: Bivariable analysis showed that employed participants were 3.4 times more likely to have A. baumannii compared to the unemployed (cOR = 3.38, 95%, CI: 1.09 - 10.43, p = 0.035). Patients who were having high BMI were likely to be infected by A. baumannii compared to those who had normal/low BMI (aOR = 11.2, 95%, CI: 3.57 - 21.11, p = 0.004). Those who were aged ≥ 50 years were 21 times more likely to be carbapenem-resistant Acinetobacter baumannii, COR = 21.0, 95% CI: 1.83 - 240.52, p = 0.011. Those who stayed in ICU for more than 30 days were 16 times more likely to be carbapenem-resistant Acinetobacter baumannii compared to those who had been admitted (COR = 16.0, 95% CI: 1.45 - 176.45, p = 0.019). Conclusion: Increased length of hospital stay, obesity and marital status were the factors found to be significantly associated with A. baumannii infections among ICU admitted patients. On the other hand, gender, age, level of education, occupation, referral status and presence of infection were found to have no significant association with A. baumannii infections among ICU admitted patients. All patients admitted to the intensive care units should be screened for colonization with A. baumannii, owing to the poor treatment outcomes associated with carriage of this multidrug resistant pathogen. Proper infection control in the ICU settings should be upheld to mitigate the spread of A. baumannii in the intensive care units.

好氧反硝化菌Acinetobacter sp.A3生长及脱氮特性影响因素的研究

好氧反硝化菌具有同步硝化反硝化的特性,在黑臭水体生物氧化处理方面备受关注。以一株从生物接触氧化反应器生物膜上分离出的好氧反硝化菌(Acinetobacter sp. A3)为研究对象,在好氧条件下研究了氮源、碳氮比(C/N)、初始pH和培养温度对Acinetobacter sp. A3菌生长及脱氮特性的影响。实验结果表明,以氨氮(NH+4-N)为氮源时,菌株生长速度更快。C/N对菌株的生长速率、细胞最高产量和脱氮效果有明显影响。增加C/N,氨氮(NH+4-N)去除速率和去除率不断提高,而硝态氮(NO-3-N)去除速率和去除率在C/N为4时达到最大。菌株在pH为7~9,温度为30~35℃时生长最快。

Clinical Distribution and Drug Resistance of Acinetobacter baumannii in a Hospital from 2019 to 2021

Objective:To analyze the clinical distribution and drug resistance of Acinetobacter baumannii(AB)and provide reference for the treatment of AB infection.Methods:AB isolated from clinical specimens of Huaihua First People’s Hospital from 2019 to 2021 were collected and identified by VITEK 2 Compact,an automated microbial identification and susceptibility testing system,in which drug sensitivity test was also performed.Excel was used for statistical analysis.Results:Among the 1,311 AB strains,81.16%(1,064 strains)were from sputum samples,and the departments with the highest detections rates of AB were neurosurgery(24.33%),intensive care(15.48%)and infectious disease(11.44%).The drug sensitivity test showed that the resistance rate of 1,311 AB strains to compound sulfamethoxazole and amikacin was 28.38%and 20.54%,respectively,and the resistance rate to 10 other kinds of common antibiotics was more than 40%.Conclusion:The 1,311 AB strains isolated were widely distributed in clinical settings and had strong resistance to commonly used antibiotics.Therefore,it is necessary to strengthen the monitoring of pathogens and drug resistance,formulate reasonable and effective infection control measures,and ensure that antibiotics are used in a reasonable manner.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

Characteristics of β-Lactamase Synthesis in E. coli and K. pneumanie Strains in Nosocomial Infections

Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.

好氧异养硝化菌Acinetobacter sp. YY-5的分离鉴定及脱氮机理

通过异养硝化培养基获得一株高效脱氮细菌,并通过形态学特征、生理生化反应及16S rDNA同源性比较对筛得菌株进行了鉴定;分别以NO3--N和NO2--N为唯一氮源,通过对脱氮过程中各种含氮代谢物的定量及对脱氮相关基因氨单加氧酶基因(amoA)、羟胺氧化酶基因(hao)、周质硝酸盐还原酶亚基基因(napA)的扩增及测序比较,对该菌株的生理途径及脱氮机理进行了研究.结果表明,高效脱氮细菌YY-5不能发生好氧反硝化,但能在3d内将氨氮由95.23mg/L降解至1.29mg/L,降解率达到98.6%,同时未发现亚硝酸盐氮、硝酸盐氮积累;对该菌主要代谢气体产物进行检测,发现CO2和N2明显增多,无N2O生成;经鉴定,初步判定该菌为不动杆菌属,命名为Acinetobacter sp. YY-5;从该菌基因组中均能扩增出amoA、hao、napA等基因,其中napA与hao基因与已报道的napA与hao基因进行Blast比较,发现具有较大差别.

Acinetobacter sp. XA05和Sphingomonas sp. FG03苯酚生物降解特性研究

从活性污泥和苯酚污染的土壤中分离出来两个菌株,分别编号为XA05和FG03.通过16S rRNA基因序列分析表明,XA05属于Acinetobacter sp.,而FG03属于Sphingomonas sp..将XA05和FG03在以不同浓度的苯酚作为唯一碳源的基础培养液中培养,结果显示,在初始苯酚浓度分别为800 mg/L和1000 mg/L时,作用45 h和60 h后,XA05和FG03对苯酚的去除率分别是99.5%、78.3%和97.6%、68.1%.两个菌株按1:1的体积比混合后,当苯酚的初始浓度分别为800 mg/L和1000 mg/L时,作用35 h和60 h后,苯酚去除率分别为99.8%,97.2%.XA05和FG03的苯酚降解动力学研究表明,在Haldane’s模型中,XA05和FG03都有较高的KS和KSI值.

Acinetobacter lwoffii ChI-06合成几丁质酶抑制剂的发酵动力学研究

对Acinetobacter lwoffii ChI-06合成几丁质酶抑制剂的发酵过程和发酵动力学进行了研究。应用Logistic方程和Luedeking-Piret方程,得到了描述菌体生长、抑制剂合成及基质消耗的动力学模型。模型反映了该菌体合成抑制剂过程的动力学特征,模型值与实验数据拟合良好。

固定化Acinetobacter sp. XA05和Sphingomonas sp. FG03降解苯酚

从活性污泥和受苯酚污染的土壤中分离出的菌株XA05和FG03均具有很强的苯酚生物降解能力。16srDNA序列分析表明,XA05和FG03菌株分别属于不动杆菌属(Acinetobacter sp.)和鞘氨醇单胞菌属(Sphin-gomonas sp.)。实验结果表明,在苯酚初始质量浓度为800.0mg/L、培养时间为35h的条件下,自由悬浮细胞和固定化细胞的苯酚降解率均高于95.0%。