Chapter 1-3. Anaerobic infections (general): drug susceptibility tests

The incidence of candidaemia among immunocompromised patients in Malaysia is increasing at an alarming rate. Isolation of clinical strains that are resistant to fluconazole has also risen markedly. We report here the repeated isolation of Candida tropicalis from the blood of a neonatal patient with Hirschsprung's disease. In vitro fluconazole susceptibility tests of the eight isolates obtained at different time points showed that seven of the isolates were resistant and one isolate was scored as susceptible dose-dependent. Random amplification of polymorphic DNA fingerprinting of the isolates using three primers and subsequent phylogenetic analysis revealed that these isolates were highly similar strains having minor genetic divergence, with a mean pairwise similarity coefficient of 0·893±0·041. The source of the infectious agent was thought to be the central venous catheter, as culture of its tip produced fluconazole-resistant C. tropicalis. This study demonstrates the utility of applying molecular epidemiology techniques to complement traditional mycological culture and drug susceptibility tests for accurate and appropriate management of recurrent candidaemia and highlights the need for newer antifungals that can combat the emergence of fluconazole-resistant C. tropicalis strains.

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Molecular Analysis of Codon 548 in therpoBGene Involved in Mycobacterium tuberculosis Resistance to Rifampin

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04374-14 ◽

2014 ◽

Vol 59 (3) ◽

pp. 1542-1548 ◽

Cited By ~ 7

Author(s):

Yu-Tze Horng ◽

Wen-Yih Jeng ◽

Yih-Yuan Chen ◽

Che-Hung Liu ◽

Horng-Yunn Dou ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Bacterial Resistance ◽

Drug Susceptibility ◽

Content Type ◽

Stable Hydrogen Bond ◽

Resistance Patterns ◽

Resistant Strains ◽

Rifampin Resistance ◽

Susceptibility Tests ◽

Dna Complex

ABSTRACTMostMycobacterium tuberculosisrifampin-resistant strains have been associated with mutations in an 81-bp rifampin resistance-determining region (RRDR) in the generpoB. However, if this region alone were targeted, rifampin-resistant strains with mutations outside the RRDR would not be detected. In this study, among 51 rifampin-resistant clinical isolates analyzed by sequencing 1,681-bp-long DNA fragments containing the RRDR, 47 isolates contained mutations within the RRDR, three isolates contained mutations both within and outside the RRDR, and only one isolate had a single missense mutation (Arg548His) located outside the RRDR. A drug susceptibility test of recombinantMycobacterium smegmatisandM. tuberculosisisolates carrying mutatedrpoB(Arg548His) showed an increased MIC for rifampin compared to that of the control strains. Modeling of the Arg548His mutant RpoB-DNA complex revealed that the His548 side chain formed a more stable hydrogen bond structure than did Arg548, reducing the flexibility of the rifampin-resistant cluster II region of RpoB, suggesting that the RpoB Arg548His mutant does not effectively interact with rifampin and results in bacterial resistance to the drug. This is the first report on the relationship between the mutation in codon 548 of RpoB and rifampin resistance in tuberculosis. The novel mutational profile of therpoBgene described here will contribute to the comprehensive understanding of rifampin resistance patterns and to the development of a useful tool for simple and rapid drug susceptibility tests.

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In Vitro Susceptibility of Mycobacterium abscessus and Mycobacterium fortuitum Isolates to 30 Antibiotics

BioMed Research International ◽

10.1155/2018/4902941 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Yaojie Shen ◽

Xuyang Wang ◽

Jialin Jin ◽

Jing Wu ◽

Xuelian Zhang ◽

...

Keyword(s):

Public Health Problem ◽

Drug Susceptibility ◽

Mycobacterium Abscessus ◽

Mycobacterium Fortuitum ◽

In Vitro Susceptibility ◽

Antitubercular Drugs ◽

Microdilution Method ◽

Susceptibility Tests ◽

Susceptibility Profiles

Objective. Nontuberculous mycobacteria (NTM) cause various diseases in humans and animals. Recently, the prevalence of NTM-related disease has been on the rise, becoming an emerging public health problem. The aim of this study was to determine the antibiotic susceptibility profiles of clinical isolates of Mycobacterium abscessus and Mycobacterium fortuitum. Methods. We performed susceptibility tests on 37 clinical NTM isolates to 30 antibiotics with the microdilution method recommended by the Clinical and Laboratory Standards Institute. Results. Both M. abscessus and M. fortuitum were highly resistant to antitubercular drugs such as isoniazid, rifampin, ethambutol, clofazimine, ethionamide, and rifabutin. M. abscessus showed the lowest resistant rates to cefoxitin (10%), azithromycin (10%), amikacin (10%), and clarithromycin (20%) and very high resistant to sulfamethoxazole, vancomycin, oxacillin, clindamycin, and all fluoroquinolones. M. fortuitum showed low resistance to tigecycline (0%), tetracycline (0%), cefmetazole (12%), imipenem (12%), linezolid (18%), and the aminoglycosides amikacin (0%), tobramycin (0%), neomycin (0%), and gentamycin (24%). Conclusion. Amikacin, cefoxitin, and azithromycin have the highest in vitro activity against M. abscessus. Isolates of M. fortuitum need to be individually evaluated for drug susceptibility before choosing an effective antimicrobial regimen for treatment of infections.

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Trends in Testing for Mycobacterium tuberculosis Complex From US Public Health Laboratories, 2009–2013

Public Health Reports ◽

10.1177/0033354916679989 ◽

2016 ◽

Vol 132 (1) ◽

pp. 56-64 ◽

Cited By ~ 4

Author(s):

Frances Tyrrell ◽

Cortney Stafford ◽

Mitchell Yakrus ◽

Monica Youngblood ◽

Andrew Hill ◽

...

Keyword(s):

Public Health ◽

Mycobacterium Tuberculosis ◽

Mycobacterium Tuberculosis Complex ◽

The United States ◽

Drug Susceptibility ◽

Turnaround Time ◽

Nucleic Acid Amplification ◽

Tuberculosis Complex ◽

Complex Detection ◽

Susceptibility Tests

Objective: We investigated data from US public health laboratories funded through the Centers for Disease Control and Prevention’s Tuberculosis Elimination and Laboratory Cooperative Agreement to document trends and challenges in meeting national objectives in tuberculosis (TB) laboratory diagnoses. Methods: We examined data on workload and turnaround time from public health laboratories’ progress reports during 2009-2013. We reviewed methodologies, laboratory roles, and progress toward rapid detection of Mycobacterium tuberculosis complex through nucleic acid amplification (NAA) testing. We compared selected data with TB surveillance reports to estimate public health laboratories’ contribution to national diagnostic services. Results: During the study period, culture and drug susceptibility tests decreased, but NAA testing increased. Public health laboratories achieved turnaround time benchmarks for drug susceptibility tests at lower levels than for acid-fast bacilli smear and identification from culture. NAA positivity in laboratories among surveillance-reported culture-positive TB cases increased from 26.6% (2355 of 8876) in 2009 to 40.0% (2948 of 7358) in 2013. Public health laboratories provided an estimated 50.9% (4285 of 8413 in 2010) to 57.2% (4210 of 7358 in 2013) of culture testing and 88.3% (6822 of 7727 in 2011) to 94.4% (6845 of 7250 in 2012) of drug susceptibility tests for all US TB cases. Conclusions: Public health laboratories contribute substantially to TB diagnoses in the United States. Although testing volumes mostly decreased, the increase in NAA testing indicates continued progress in rapid M tuberculosis complex detection.

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Proficiency testing of conventional drug susceptibility tests of Mycobacterium tuberculosis

Canadian Journal of Microbiology ◽

10.1139/m87-186 ◽

1987 ◽

Vol 33 (12) ◽

pp. 1064-1068 ◽

Cited By ~ 2

Author(s):

Adalbert Laszlo ◽

Dorothy M. Helbecque ◽

Walter Tostowaryk

Keyword(s):

Mycobacterium Tuberculosis ◽

Proficiency Testing ◽

Susceptibility Testing ◽

Developed Countries ◽

Drug Susceptibility ◽

Reference Laboratory ◽

In Vitro Susceptibility ◽

Testing Procedures ◽

Drug Concentrations ◽

Susceptibility Tests

Proficiency testing of indirect drug susceptibility tests of Mycobacterium tuberculosis was begun in 1985 by the Laboratory Centre for Disease Control (LCDC) with the participation of Provincial Public Health Laboratories in Canada. Comparable sets of 60 cultures of Mycobacterium tuberculosis representing 30 strains were distributed by LCDC to the participating laboratories to be tested for drug susceptibility against isoniazid, streptomycin, rifampin, and ethambutol using conventional methodologies. Intralaboratory agreement values determined by comparing results obtained on sets of duplicate cultures were high and were found to vary little from drug to drug and from laboratory to laboratory. Interlaboratory agreement was determined by comparing results reported by participating laboratories to those obtained by the Reference Laboratory. Agreement percentages were found to be lower for drug-resistant cultures than for drug-susceptible cultures. The reliability of drug susceptibility testing results was higher for isoniazid and rifampin, than for ethambutol and streptomycin. This study shows that the higher subsidiary drug concentrations do not compare well with main drug concentrations, especially in the case of streptomycin and ethambutol. The significance of the higher subsidiary concentrations in in vitro susceptibility testing is therefore in need of clarification. The proficiency testing results obtained in this study compare favorably with those reported in other developed countries despite the fact that a variety of testing procedures are used throughout the country.

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Microscopic Observation Drug Susceptibility (MODS) Assay: A Convenient Method for Determining Antibiogram of Clinical Isolates of Mycobacterium tuberculosis in Ghana

Medical Sciences ◽

10.3390/medsci8010005 ◽

2020 ◽

Vol 8 (1) ◽

pp. 5

Author(s):

Enid Owusu ◽

Mercy Jemima Newman

Keyword(s):

Mycobacterium Tuberculosis ◽

Rural Areas ◽

Microscopic Observation ◽

Drug Susceptibility ◽

Ease Of Use ◽

Health Centers ◽

Culture Methods ◽

Susceptibility Tests ◽

User Friendly

(1) Background: Present methods for drug susceptibility tests (DST) rely on culture methods that are sophisticated and relatively faster, or a slow and cheaper option. These methods frustrate disease control; therefore, there is a need for methods that incorporate key functions of microscopy and culture, with reduced cost burden and sophistry. Thus, the purpose of this study was to identify which, among the most commonly used (in Ghana) methods, can conveniently be used at health centers located in rural areas for effective DST determination of Mycobacterium tuberculosis (MTB). (2) Methods: Mycobacterium tuberculosis isolates were tested for their susceptibility to streptomycin, isoniazid, rifampicin, ethambutol (SIRE), and pyrazinamide by microscopic observation drug susceptibility (MODS) and BACTEC MGIT 960 methods. Evaluations were based on shorter turnaround periods, rapidity, ease of use, cost, etc. A comparative analysis was statistically expressed as kappa values. (3) Results: Endpoints for drug susceptibilities by MODS averaged 13 days (7–32), whilst that for BACTEC MGIT 960 was 10 days with a further 12 days to detect resistance. Therefore, a turnaround period of 22 days was needed for DST by BACTEC MGIT 960, compared to 13 days for MODS. There were differences in correlation levels between the two methods, as determined by their kappa values. (4) Conclusion: The MODS assay was found to be less costly, more user-friendly, and still able to be conveniently used at health centers located in rural areas known to be endemic for TB, particularly in Ghana.

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Chapter 1-6. Anaerobic infections (general): care needed when dealing with patients who have underlying diseases or complications

Journal of Infection and Chemotherapy ◽

10.1007/s10156-010-0136-7 ◽

2011 ◽

Vol 17 ◽

pp. 40-41

Keyword(s):

Anaerobic Infections ◽

Underlying Diseases ◽

General Care

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Efficacy of Clarithromycin against Experimentally Induced Pneumonia Caused by Clarithromycin-Resistant Haemophilus influenzae in Mice

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00524-09 ◽

2009 ◽

Vol 54 (2) ◽

pp. 757-762 ◽

Cited By ~ 10

Author(s):

Shigeki Nakamura ◽

Katsunori Yanagihara ◽

Nobuko Araki ◽

Koichi Yamada ◽

Yoshitomo Morinaga ◽

...

Keyword(s):

Haemophilus Influenzae ◽

Inflammatory Cells ◽

Lavage Fluid ◽

Drug Susceptibility ◽

Control Group ◽

Inflammatory Protein ◽

Conventional Drug ◽

Good Penetration ◽

Susceptibility Tests

ABSTRACT Clarithromycin is a 14-member lactone ring macrolide with potent activity against Haemophilus influenzae, including ampicillin-resistant strains. We evaluated the in vivo efficacy of clarithromycin at 40 mg/day and 100 mg/day for 3 days in the treatment of a murine model of pneumonia using a macrolide-resistant H. influenzae strain, which was also ampicillin resistant. The MIC of clarithromycin was 64 μg/ml. The viable bacterial counts in infected tissues after treatment with 100 mg clarithromycin/kg of body weight were lower than the counts obtained in control and 40-mg/kg clarithromycin-treated mice. The concentrations of macrophage inflammatory protein 2 (MIP-2) and interleukin 1β (IL-1β) in bronchoalveolar lavage fluid (BALF) samples from mice treated at both concentrations were lower than in the control group. Pathologically, following infection, clarithromycin-treated mice, particularly at a dose of 100 mg/kg, showed lower numbers of neutrophils in alveolar walls, and inflammatory changes had apparently improved, whereas large aggregates of inflammatory cells were observed within the alveoli of control mice. In addition, we demonstrated that clarithromycin has bacteriological effects against intracellular bacteria at levels below the MIC. Our results indicate that clarithromycin may be useful in vivo for macrolide-resistant H. influenzae, and this phenomenon may be related to the good penetration of clarithromycin into bronchoepithelial cells. We also believe that conventional drug susceptibility tests may not reflect the in vivo effects of clarithromycin.

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