Susceptibility testing for aztreonam plus ceftazidime/avibactam combination: A general guidance for clinical microbiology laboratories in India

Metallo beta-lactamases-producing Gram-negative infection is often challenging and there is no defined treatment option. In recent years, the combination of aztreonam with ceftazidime-avibactam has gained much clinical attention mainly for MBL-producing Enterobacterales, while MBL-producing P. aeruginosa and A. baumannii are likely to be resistant. A consensus susceptibility testing method for this triple combination has yet to be recommended. Various methods such as broth disk elution, disk stacking, gradient strip stacking, and strip crossing have been proposed for testing this combination. Among them, broth disk elution and strip based testing methods showed good correlation with the broth micro-dilution method.

Treatment for abdominal infection caused by metallo- β-lactamase-producing Klebsiella pneumoniae in an infant after liver transplantation ：a case report and literature review / 中国药房

OBJECTIVE To investigate the treatment plan for az treonam-resistant metallo- β-lactamase（MBL）-producing Enterobacteriaceae infection in pediatric solid organ transplant recipients. METHODS The clinical data of aztreonam-resistant MBL-producing Klebsiella pneumoniae caused intra-abdominal infection of an infant after liver transplantation were retrospectively analyzed. Abdominal infection occurred after operation. The pathogenic bacterium was MBL-producing K. pneumoniae . The drug sensitivity results showed that the infant was resistant to aztreonam. Based on the results of sensitivity test ，polymyxin B combined with tigecycline were selected as initial regimen. The treatment effect was poor ，with recurrent disease and shock spots. The clinical pharmacist assisted the clinician to formulate treatment regimen of ceftazidime avibactam 0.5 g，q8 h combined with aztreonam 0.18 g，q6 h. Relevant domestic and foreign literature were reviewed ，and the treatment plan of MBL-producing Enterobacteriaceae infection after solid organ transplantation was summarized. RESULTS & CONCLUSIONS The infant was finally cured and discharged with ceftazidime avibatan combined and aztreonam. Several foreign literature reported that ceftazidime avibactam combined with aztreonam could effectively treat the infection caused by aztreonam-resistant MBL-producing Enterobacteriaceae infection in patients with organ transplantation. It is expected to be an effective treatment for aztreonam-resistant MBL-producing Enterobacteriaceae infection in pediatric solid organ transplant recipients.

Caracterização molecular e fenotípica de Klebsiella spp. produtoras de NDM / Molecular and phenotypic characterization of Klebsiella spp. NDM producers

O perfil de resistência, que algumas das espécies do complexo Klebsiella pneumoniae podem expressar, representa uma grande ameaça à saúde humana, particularmente quando resistentes aos carbapenêmicos, que são amplamente utilizados no tratamento de infecções graves em pacientes hospitalizados. O principal mecanismo de resistência aos carbapenêmicos é a produção de carbapenemases, particularmente dos tipos KPC e NDM. Um dos compostos desenvolvidos para o tratamento de infecções causadas por cepas produtoras de KPC é a combinação ceftazidimaavibactam (CAZ-AVI), mas que não tem atividade inibitória sobre metalo-betalactamases, a exemplo das NDMs. Os objetivos deste trabalho foram determinar a frequência das espécies do complexo K. pneumoniae e da coprodução de KPC, avaliar a clonalidade dos isolados, a sensibilidade ao aztreonam-avibactam (ATM-AVI), o desempenho do disco de meropenem (MEM) com inibidores para detecção de coprodução de NDM e KPC e desenvolver um teste de triagem para prever a sensibilidade ao ATM-AVI. Um total de 113 isolados do complexo K. pneumoniae produtoras de NDM ou coprodutoras de NDM e KPC, provenientes da coleção de bactérias do Grupo Fleury, coletadas períodos pré e pós início do uso de CAZ-AVI no Brasil, foram utilizadas neste estudo. A identificação da espécie e a presença dos genes blaNDM e blaKPC foi confirmada por PCR multiplex. A clonalidade dos isolados foi avaliada por eletroforese em campos pulsados (PFGE) após clivagem com XbaI. A produção de carbapenemases foi confirmada utilizando-se o teste Blue Carba. O desempenho dos discos de meropenem e CAZ-AVI contendo um ou mais inibidores de carbapenemases foi comparado com o teste molecular. A pré-difusão combinada foi realizada pré-incubando-se o ágar não inoculado com disco de CAZ-AVI, e a seguir aplicando-se o inóculo bacteriano e um disco de ATM após remover o disco de CAZ-AVI. Após incubação, os halos foram aferidos e correlacionados com a concentração inibitória mínima para ATM-AVI. As CIMs para ATM e ATM-AVI foram determinadas segundo o EUCAST. A identificação das espécies por PCR evidenciou as seguintes frequências: K. pneumoniae 75,2% (n=85); K. quasipneumoniae 16,8% (n=19), e K. variicola 8% (n=9). Uma fração de 12,4% (n=14) dos isolados apresentaram os genes blaNDM e blaKPC e 87,6% (n=99) apenas blaNDM. A análise dos perfis de PFGE de K. pneumoniae evidenciou a presença de cinco grupos clonais predominantes. Isolados do principal grupo clonal Ap (n=15) foram detectados nas cidades de São Paulo e Porto Alegre durante todo o período analisado. O grupo clonal Lp foi detectado nas cidades de São Paulo e Recife em 2019. Os dois principais grupos clonais no período pré-CAZ-AVI continham maior número de isolados do que aqueles no período de uso do CAZ-AVI. Os perfis de PFGE de K. quasipneumoniae evidenciaram quatro grupos clonais predominantes, e presentes apenas no estado de São Paulo, com persistência do grupo clonal Aq desde 2017. Quanto à K. variicola, foram observados dois grupos clonais predominantes Av e Bv, o primeiro presente apenas em São Paulo desde 2018 e o segundo em Porto Alegre apenas em 2019. Calculando-se a diferença entre os diâmetros de halo do disco MEM contendo EDTA e ácido fenilborônico (AFB) e o maior dos halos obtidos para MEM com EDTA ou AFB, observou-se que todos os isolados com coexpressão de KPC e NDM apresentaram diferença ≥ 5 mm. Uma fração de 42,3% dos isolados positivos apenas para blaNDM apresentaram sensibilidade para ATM (CIM ≤ 4 mg/L). Todos os isolados testados apresentaram CIM para ATM-AVI ≤ 1/4 mg/L, sendo a CIM90 0,125/4 mg/l. No teste de pré-difusão combinada, o menor diâmetro de halo obtido foi de 23 mm. A espécie predominante na amostragem foi K. pneumoniae. A disseminação clonal, observada neste estudo, contrasta com a diversidade clonal descrita em outros locais do mundo para produtores de NDM, exceto Grécia e China. Considerando os pontos de corte atuais para ATM, é provável que haja resposta clínica adequada no uso de ATM-AVI no tratamento de infecções causadas por isolados produtores de NDM e coprodutores de KPC e NDM. Utilizando-se o valor de corte de ≤ 5 mm para a diferença entre halos de inibição, de MEM com AFB e EDTA e o segundo maior halo com inibidor, a sensibilidade foi de 100% e a especificidade foi de 96,1,0%. O método de pré-difusão com CAZ-AVI e ATM é um método simples e o diâmetro ≥ 23 mm tem excelente correlação com a CIM para ATM-AVI ≤ 1/4 mg/L

The resistance profile, which some species of the Klebsiella pneumoniae complex may express, represent a great threat to human health, particularly when resistant to carbapenems, which are widely used in the treatment of severe infections in hospitalized patients. The main mechanism of resistance to carbapenems is the production of carbapenemases, particularly KPCs and NDMs. One of the compounds developed for the treatment of infections caused by KPC-producing strains is the combination ceftazidime-avibactam (CAZ-AVI), but which has no inhibitory activity on metallobetalactamases, as is the case for NDMs. The objectives of this work were to determine the frequency of K. pneumoniae complex species and KPC co-production, evaluate the clonality of isolates, the susceptibility to aztreonam-avibactam (ATM-AVI), the performance of meropenem (MEM) disks with inhibitors for detecting NDM co-production and KPC and develop a screening test to predict sensitivity to ATM-AVI. A total of 113 NDM-producing or NDM and KPC co-producing K. pneumoniae complexes, from the Fleury Group's bacteria collection, collected in the pre- and post-starting periods of CAZ-AVI use in Brazil, were used in this study. Species identification and the presence of the blaNDM and blaKPC genes were confirmed by multiplex PCR. The clonality of the isolates was evaluated by pulsed field electrophoresis (PFGE) after cleavage with XbaI. Carbapenemase production was confirmed using the Blue Carba test. The performance of MEM and CAZ-AVI disks containing one or more carbapenemase inhibitors was compared with the molecular test. Combined pre-diffusion was performed by preincubating the uninoculated agar with a CAZ-AVI disk, and then applying the bacterial inoculum and na ATM disk after removal of the CAZ-AVI disk. After incubation, halos were measured and correlated with the minimum inhibitory concentration (MIC) for ATM-AVI. ATM and ATM-AVI MICs were determined according to EUCAST. The identification of species by PCR evidenced the following frequencies: K. pneumoniae 75.2% (n=85); K. quasipneumoniae 16.8% (n=19), and K. variicola 8% (n=9). A fraction of 12.4% (n=14) of the isolates had the blaNDM and blaKPC genes and 87.6% (n=99) had only blaNDM. The analysis of the PFGE profiles of K. pneumoniae evidenced the presence of five predominant clonal groups. Isolates from the main clonal group Ap (n=16) were detected in the cities of São Paulo and Porto Alegre throughout the analyzed period. The clonal group Lp was detected in the cities of São Paulo and Recife 2019. The PFGE profiles of K. quasipneumoniae showed four predominant clonal groups, present only in the state of São Paulo, with persistence of the clonal group Aq since 2017. As for K. variicola, two predominant clonal groups Av and Bv were observed, the first present only in São Paulo since 2018 and the second in Porto Alegre only in 2019. Calculating the difference between the inhibition zone diameters of the MEM disk containing EDTA and phenylboronic acid (AFB) and the largest of the inhibition zone diameters obtained for MEM with EDTA or AFB, it was observed that all isolates with co-expression of KPC and NDM showed a difference 5 ≥mm. A fraction of 42.3% of isolates positive only for blaNDM showed sensitivity to ATM (MIC ≤ 4 mg/L). All tested isolates presented MIC for ATM-AVI ≤ 1/4 mg/L, being the MIC90 0.125/4 mg/l. In the combined pre-diffusion test, the smallest inhibition zone diameter obtained was 23 mm. The predominant species in the sample was K. pneumoniae, but a significant fraction of the other species in the complex was also observed in the sample. The clonal spread observed in this study contrasts with the clonal diversity described elsewhere in the world for NDM-producing isolates, except Greece and China. Considering the current cut-off points for ATM, it is likely that there is an adequate clinical response in the use of ATM-AVI in infections caused by NDM-producing and KPC-NDM co-producing isolates in Brazil. Using the cutoff value of 5 mm for the difference between inhibition zones, of MEM with AFB and EDTA and the second largest zone of MEM with inhibitor, the sensitivity was 100% and the specificity was 96.1%. The pre-diffusion method with CAZ-AVI and ATM is a simple method and the diameter ≥ 23 mm has excellent correlation with the MIC for ATM-AVI ≤ 1/4 mg/L

Will ceftazidime/avibactam plus aztreonam be effective for NDM and OXA-48-Like producing organisms: Lessons learnt from In vitro study

Introduction: Carbapenem resistance (CR) in Klebsiella pneumoniae is mainly mediated by bla NDM and bla OXA-48 carbapenemases. Newer Food and Drug Administration-approved antimicrobial ceftazidime/avibactam (C/A) has a potent activity against bla OXA-48-like producers. However, its activity is limited in organisms co-producing bla NDM and bla OXA-48-like. Addition of aztreonam (ATM) to C/A potentially expands the spectrum of coverage for carbapenemase co-producers. With this, we aimed to determine the synergistic activity of combination of C/A plus ATM against bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48-like producing CR Klebsiella pneumoniae (CRKp). Materials and Methods: A total of 12 isolates of CRKp-harbouring genes encoding bla NDM and bla OXA-48-like were tested. Minimum inhibitory concentrations (MICs) were determined for several antimicrobial agents, including C/A (0.5�?g/ml) by broth microdilution method. Checkerboard assay was performed for the combination of C/A plus ATM at varying concentrations. Fold differences in the MIC of C/A with and without addition of ATM were determined to infer synergistic effects. Results: MIC of C/A and ATM ranged from 0.5 to >8 ?g/ml and 64 to 2048 ?g/ml, respectively. Two isolates were susceptible to C/A with MIC of 0.5 and 1 ?g/ml, while others were resistant with MIC of >8 ?g/ml. Synergistic effects of >8-fold MIC difference in C/A MIC were noted with addition of ATM at 4 ?g/ml. This was observed for all CRKp with profiles of bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48-like genes, which was a promising effect. Notably, all five of the colistin-resistant CRKp were inhibited with >8-fold MIC difference in the combination of C/A plus ATM at 4 ?g/ml. Conclusion: With the increasing burden of CRKp, the use of C/A with ATM combination seems to be very promising, especially for bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48like carbapenemases.

Antibacterial Activity and Mechanism of Fusidic Acid Combined with Aztreonam Against Carbapenem-Resistant Pseudomonas aeruginosain In Vitro / 中国药学杂志

OBJECTIVE: To explore the antibacterial activity and mechanism of fusidic acid combined with aztreonam on 12 clinical isolates of carbapenem-resistant Pseudomonas aeruginosa (CRPA). METHODS: Broth dilution method was used to determine the minimum inhibitory concentration(MIC) of the fusidic acid and aztreonam combination.The MIC of two drugs combination were measured by the checkerboard method and partial inhibitory concentration index (FIC) was calculated to determine the combined effect.The synergistic effect of two drugs was assessed by the disk diffusion susceptibility test and the time-killing curves.Extracellular enzyme activity assay was used to detect the strains extracellular enzyme activity changes of fusidic acid alone and combined with aztreonam. The probable mechanism of the combined use of two drugs was discussed. RESULTS: Fusidic acid and aztreonam combination displayed synergistic and additive activity on 61.54% and 38.46% isolates, no antagonism activity was observed.The bacteriostasis circle was obviously increased in two drugs combination, of which 41.67% of the strains were changed from drug resistance to sensitive. The time-killing curves showed that the combined of two drugs had bactericidal effect on the isolate PA 320.Extracellular aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) activity were all increased in a significant difference with the combination of two drugs. CONCLUSION: Fusidic acid combined with aztreonam on CRPA is showed synergistic and additive activity in vitro. The mechanism of two drugs in combination may concern with aztreonam help the fusidic acid to overcome the natural hydrophobic antibiotic permeability barriers of gram-negative bacteria.

Analysis of aztreonam and metronidazole in blood by ultra performance liquid chromatography-tandem mass spectrometry / 复旦学报（医学版）

Objective To establish a UPLC-MS/MS method for the determination of aztreonam and metronidazole in blood.Methods Cefradine and chloramphenicol were used as the internal standard.Blood sample was made by protein precipitation with acetonitrile,and then was seprated by HPLC.Multiple reaction monitoring mode (MRM) for the parent ion and ion monitoring was used for each compound.Results The linearity of aztreonam in the range from 10 to 5 000 ng/mL and metronidazole in the range from 1 to 1 000 ng/mL were good (r＞0.995).The quantification limit of the method for aztreonam and metronidazole were 5 and 0.5 ng/mL,respectively (S/N =3 ∶ 1).The inter-day and intra-day relative standard deviations (RSD) were less than 10 ％.The established method was used to detect aztreonam and metronidazole in a medical dispute case,the concentrations of aztreonam and metronidazole in the blood were 438 ng/mL and 15 μg/mL,respectively.Conclusions The method developed in the study is simple,sensitive and reproducible with its successful application into the qualitative and quantitative analysis of aztreonam and metronidazole.

Effects of Aztreonam combined Azithromycin on Pseudomonas aeruginosa bioflim / 中国临床药理学与治疗学

AIM:To investigate the effect and mechanism of Aztreonam combined Azithromycin on Pseudomonas aeruginosa ATCC 27853,and clinical separation of 15 strains of Pseudomonas aeruginosain vitro.METHODS:Broth dilution method and checkerboard dilution method were used to determine Aztreonam alone or in combination with Azithromycin on Pseudomonas aeruginosa ATCC27853 and 15 clinical isolates of Pseudomonas aeruginosa.Then,the biofilm formation of the clinical separation of 15 strains of Pseudomonas aeruginosa was identified by Congo red plate method.The crystal violet experiment was used to compare the ability of biofilm formation of Pseudomonas aeruginosa.Growth curve and viable count of Pseudomonas aeruginosa biofilm were investigated by continuous dilution method.The silver staining method was used to observe the biofilm of Pseudomonas aeruginosa by Aztreonam alone and in combination with Azithromycin.RESULTS:Azithromycin combined with Azithromycin on Pseudomonas aeruginosa ATCC 27853 showed synergistic effect;of the 15 isolates of Pseudomonas aeruginosa,6 were synergistic,6 additive,and 3 irrelevant.Congo red plate experiments show that the clinical separation of 15 strains of Pseudomonas aeruginosa,12 strains can formed biofilm,3 did not formed biofilm,and the rate of biofilm formation was 80％.The results of crystal violet experiment showed that the biofilm formation ability of 16091217 was the strongest when compared with other strains.The continuous dilution method of viable bacteria count experiment showed that the number of viable bacteria in Azithromycin group,Aztreonam group was significantly different compared with Azithromycin + Aztreonam group.The silver staining method showed that the inhibition effect of Azithromycin on the formation,early and mature stages of biofilm formation.CONCLUSION:The study found that the effect of Aztreonam combined with Azithromycin was mainly synergistic and additive in vitro.Aztreonam combined with Azithromycin presents synergistic bactericidal effect on Pseudomonas aeruginosa biofilm formation.

Efficacy evaluation of aztreonam in combination with cefepime for the treatment of urinary tract infectious / 中国基层医药

Objective To explore the clinical efficacy of aztreonam in combination with cefepime for the treatment of urinary tract infections.Methods A randomized block grouping,123 cases of urinary tract infections were divided into observation group,aztreonam group and cefepime group,41 cases in each group.The observation group was treated with aztreonam (2.0g) and cefepime (2.0g),control group were given aztreonam and cefepime,respectively.The treatment time lasted 7 days.Results The total effective rate of observation group was 95.1％,compared with cefepime(85.4％)or aztreonam(82.9％) group,the difference was statistically significant(x2 =12.89、13.56,all P ＜ 0.05).After the end of treatment,the observation group bacterial clearance rate (94.3％) was slightly higher than that of cefepime group or aztreonam group.Each group had only minor adverse reaction,which did't affect the continued medication.And the difference in the incidence was not statistically significant(P ＞0.05).Conclusion Cefepime joint aztreonam in the treatment of urinary tract infection can improve the therapeutic efficacy,and adverse events doesn't increase.

Tigeciclina versus vancomycin más aztreonam en el tratamiento de infecciones complicadas de piel y tejidos blandos: Experiencia en Latinoamérica / Tigecycline as effective as vancomycin plus aztreonam in the treatment of complicated skin and skin structure infections: Experience in Latin America

BACKGROUND: Treating complicated skin and skin structure infections (cSSSIs) can be challenging. Tigecycline was compared to vancomycin/aztreonam in patients with cSSSIs in a multinational trial; this article reports on the Latin American (LA) population. METHODS: Patients were randomly assigned to receive tigecycline or vancomycin/ aztreonam. Primary endpoint was clinical cure rate at test-of-cure (TOC). Several secondary endpoints and safety were also assessed. RESULTS: A subtotal of 167 LA patients from the multinational trial (N = 573) received ≥ 1 dose of study drug. At TOC, cure rates were similar between tigecycline and vancomycin/aztreonam in the clinically evaluable population.) Noninferiority of tigecycline could not be demonstrated (insufficient sample sizes). Tigecycline-treated patients had higher incidences of nausea, vomiting, anorexia; vancomycin/aztreonam-treated patients had higher incidences of pruritus and rash. CONCLUSIONS: Efficacy results in the LA population were consistent with the multinational study suggesting that tigecycline is noninferior to vancomycin/aztreonam in treating patients with cSSSI.

INTRODUCCIÓN: El tratamiento de infecciones complicadas de piel y tejidos blandos (ICPTB) puede representar un desafío. Se comparó la eficacia de tigeciclina versus vancomicina/aztreonam en pacientes con ICPTB en un estudio multicéntrico; este artículo se refiere a la experiencia en Latinoamérica (LA). MÉTODO: Se asignaron, en forma randomizada, los pacientes a dos grupos de tratamiento: tigeciclina o vancomicina/aztreonam. La meta a evaluar (outcome) primaria fue la curación clínica, denominada test de curación (TC). Se establecieron, además, metas secundarias y la evaluación de seguridad del fármaco. RESULTADOS: Un subtotal de 167 pacientes procedentes de LA, de un estudio multinacional que incluyó 573 pacientes, recibieron ≥ 1 dosis del fármaco en estudio. Al TC, los porcentajes de curación fueron similares entre tigeciclina y vanco-micina/aztreonam en los pacientes clínicamente evaluables). La no inferioridad de tigeciclina no pudo ser demostrada (tamaño de muestra insuficiente). Los pacientes tratados con tigeciclina tuvieron mayor incidencia de náuseas, vómitos y anorexia; los pacientes que recibieron vancomicina/aztreonam tuvieron mayor incidencia de prurito y rash. CONCLUSIONES: Los resultados de eficacia en LA fueron consistentes con el estudio multinacional sugiriendo que tigeciclina no es inferior a vancomicina/aztreonam en el tratamiento de pacientes con ICPTB.

Analysis on Perioperative Use of Aztreonam in a Hospital / 中国药房

OBJECTIVE:To investigate the utilization of aztreonam in perioperative patients in order to promote rational use of antimicrobial agents. METHODS: 215 discharged surgery cases were collected in Mar. 2009 and analyzed retrospectively to evaluate the rationality of drug use. RESULTS: Of 215 cases, preventive use accounted for 122 cases, among which rational use 29 cases and irrational use 93 cases; treatment use accounted for 93 cases, among which reasonable use 54 cases and unreasonable use 39 cases. CONCLUSION: Perioperative use of aztreonam was not in line with Guiding Principles for Clinical Use of Antibacterial Drugs, Notice for Further Strengthen Management of Clinical Use of Antibacterial Drugs Issued by General Office of the Ministry of Health. Unreasonable utilization require to arouse attention of medical personnel and strengthen management.

Prevalence of Extended-spectrum beta-lactamase-producing Enterobacteriaceae and Evaluation of Methods for Detection / 대한임상미생물학회지

BACKGROUND: Increased isolation of extended-spectrum beta-lactamase (ESBL)-producing Entero bacteriaceae resistant to third generation cephalosporins and aztreonam has been noted recently. This study was to determine the prevalence of resistance to these drugs and ESBL in Enterobacteriaceae and to evaluate the methods for de tection. METHODS: During the period of October, 1997 and March, 1998, a total of 731 clinical isolates of Enterobacteriaceae were collected from patients of the Kosin Medical Center, Pusan, Korea. Antimicrobial susceptibility test by disk diffusion method and double disk synergy test were performed. MICs of beta-lactams were determined by agar dilution method. And ESBL genotypes were determined by polymerase chain reaction. RESULTS: About 10% of Escherichia coli isolates and 20% of Klebsiella pneumoniae isolates were intermediate or resistant to the third generation cephalosporins or aztreonam. Sensitivities of cefotaxime, ceftazidime, ceftriaxone and cefpodoxime disks for the detection of ESBL- producing strains of E. coli and K. pneumoniae by NCCLS standards were 100%, respectively, but that of aztreonam disk was 97%. Positive predictive value of the ceftazidime disk was higher than those of other disks. Twenty strains of E. coli, 20 K pneumoniae, 19 Enterobacter spp., six Citrobacter freundii, and eight Serratia marcescens showed positive results in double disk synergy test. The transconjugant strain of K. pneumoniae K20482 had blaSHV, and remains of transconjugants of ESBL-producing K. pneumoniae, Enterobacter spp. and S. marcescens had blaTEM. CONCLUSIONS: In this study, many strains of Enterobacteriaceae isolated in Korea were resistant to third generation cephalosporins and aztreonam. Some of the strains of Enterobacter spp. and S. marcescens as well as E. coli and K. pneumoniae produced ESBL, and majority of these strains had blaTEM. In the detection of ESBL-producing strains of E. coli and K. pneumoniae by NCCLS standards, all of the antimicrobial agent disks tested were useful, but ceftazidime disk was most effective because of its highest positive predictive value.

Drug Resistance to Aztreonam in Commonly Encountered Gram-negative Bacilli / 中华医院感染学杂志

OBJECTIVE To obtain primary knowledge of drug resistance to aztreonam(ATM) in commonly encounterd Gram-negative bacilli in our hospital thereby to bring the situation under control.METHODS A total of 3 928 strains of pathogenic bacteria were isolated from patients from 2001 to 2005,and drug resistance of these strains to ATM was examined.RESULTS Resistance of Pseudomonas aeruginosa,Klebsiella pneumoniae,Enterobacter cloacae and Acinetobacter spp to ATM was found to be tend increasing from 13%,14%,29% and 40% in 2001 to 28%,29%,40% and 77% in 2005.CONCLUSIONS The percentages of commonly encountered Gram-negative bacilli that are resistant to ATM have been considerably high and tend to increase further.ATM abuse needs to be given appropriate attention to.

Results of secondary antibiotics susceptibility test for gram negative bacilli resistant to primary susceptibility test in Yeungnam University Hospital / 영남의대학술지

Major pathogenic Gramnegative organisms such as P. aeruginosa, Serratia species, E. coli, Enterobacter species which are isolated from the specimens in large medical centers are greatly resistant to the commonly used antibiotics. Gramnegative bacilli, which had been isolated in Yeungnam Uni rersity Hospital during the period from December 1992 to April 1993 and turned out to be resistant to the primary antibiotics susceptibility test for chloramphenicoi, ampicillin, eephaiothin,- geniamicitt, tetracyclin, amikin and tobramycin, were subjected to the secondary antibiotics susceptibility test for aztreonam, ceftazidime, ciprofloxacine, cefotaxime, cefamandole, piperacillin, ticarcillin and sulfamethoxazole trimethopime. Out of 315 tested organisms, 167 organisms (53%) were resistant to all secondary antibiotics in vitro. Antimicrobial activity of ceftazidime (37.1%), aztreonam (11. %), ciprofloxacine (7.9%) against Gram negative bacilli were slightly more active than other antibiotics tested, while cefamandole was not active to all the Gramnegative bacilli tested. According to the specimens, E. coli was the most frequently resistant organisms to the primary antibiotics from urine, A. baumanii, from respiratory system and wounds, and P. aeruginosa from various specimens. In summary, Gram negative bacilli resistant to the primarily applied antibiotics also were resistant to the secondary antibiotics. Rearrangement of the antibiotics disks for the antibiotic susceptibility test should be considered.

Study on the Compatibility of Aztreonam for Injection with 3 Kinds of Infusions / 中国药房

OBJECTIVE: To study the compatibility stability of aztreonam after mixing with fructose injection, calorose injection and xylital injection. METHODS: The content of solution, quantity of particles, pH value and physical changes were observed after aztreonam mixing with 3 kinds of injections for 6 hours at room temperature. RESULTS: The content of solution, quantity of particles, pH value and physical changes were up to the standard. CONCLUSION: Aztreonam mixed with fructose injection, calorose injection or xylital injection is keeping stable.