Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Bhanu K Bhakhri

"The Journal of Clinical and Diagnostic Research (JCDR) has been in operation since almost a decade. It has contributed a huge number of peer reviewed articles, across a spectrum of medical disciplines, to the medical literature.
Its wide based indexing and open access publications attracts many authors as well as readers
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Faculty, Pediatric Medicine
Super Speciality Paediatric Hospital and Post Graduate Teaching Institute, Noida
On Sep 2018




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On Sep 2018




Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."



Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018




Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."



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Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018




Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
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Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
Lucknow
On Sep 2018




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MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata




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Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
Muzaffarnagar.
On Aug 2018




Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".



Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
Bengaluru.
On Aug 2018




Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
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Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".



Dr. Mamta Gupta
Consultant
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018




Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.


Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."



Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
E-mail: drrajendrak1@rediffmail.com
On May 11,2011




Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."



Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
E-mail: ravi.dr.shankar@gmail.com
On April 2011

Important Notice

Original article / research
Year : 2010 | Month : August | Volume : 4 | Issue : 4 | Page : 2691 - 2696

Metallobetalactamase Producing Pseudomonas Aeruginosa: An Emerging Threat To Clinicians

ATTAL RO, BASAK S, MALLICK S K , BOSE S

*(M.B.B.S.), (Tutor), **(M.D.) Professor of Microbiology , ***(Tutor0,Deptt. Of Microbiology, ****(M.D.) Professor of Microbiology Jawaharlal Nehru Medical College, Wardha(M.S.) 442004 Deptt. Of Microbiology.

Correspondence Address :
Dr. S. Basak. M.D. Professor of Microbiology
Jawaharlal Nehru Medical College,
Wardha(M.S.) 442004
E mail: drsilpibasak@gmail.com

Abstract

In recent years, carbapenem resistance due to the production of metallobetalactamase (MBL) in Pseudomonas aeruginosa and other Gram negative bacilli have been reported worldwide. Metallobetalactamase producing P. aeruginosa constitute nearly 20% of all nosocomial isolates. The present study was undertaken to detect the prevalence of metallobetalactamase producing P. aeruginosa in our hospital and to evaluate an easy, but specific test for the detection of metallobetalactamase production so that it would be feasible for our laboratory.
A total number of 140 P. aeruginosa strains which were isolated from different clinicalspecimens were studied. An antibiotic susceptibility test with antipseudomonal antibiotics was done as per CLSI guidelines. Imipenem resistant isolates were screened for carbapenem hydrolysis by the Hodge test and the modified Hodge test. Metallobetalactamase production was detected by the double disk synergy test (DDST) and the disk potentiation test.
Out of 140 P. aeruginosa strains, 18 (12.9%) were imipenem resistant. Amongst these 18 strains, 16(88.8%) were Hodge test and modified Hodge test positive and all 16 were found to be metallobetalactamase producers by the DDST and the disk potentiation tests.
We hereby conclude that the detection of metallobetalactamase producing P. aeruginosa strains by the disk potentiation test should be introduced in any clinical Microbiology laboratory in order to aid infection control.

How to cite this article :

ATTAL RO*, BASAK S**, MALLICK S K ***, BOSE S****. METALLOBETALACTAMASE PRODUCING PSEUDOMONAS AERUGINOSA: AN EMERGING THREAT TO CLINICIANS . Journal of Clinical and Diagnostic Research [serial online] 2010 August [cited: 2019 Oct 16 ]; 4:2691-2696. Available from
http://jcdr.net/back_issues.asp?issn=0973-709x&year=2010&month=August&volume=4&issue=4&page=2691-2696&id=807

Introduction
Carbapenem resistance in Gram negative bacteria occurs mainly due to decreased outer membrane permeability, increased efflux pumps, alteration of penicillin binding proteins and carbapenem hydrolyzing enzymes i.e. carbapenemases. According to the Ambler scheme, carbapenemases can be classified into 3 molecular classes: class A (penicillinase), class B (metallobetalactamases i.e. MBL) and class D (oxacillinase)(1). As per the Bush Jacoby-Mederios classification, the MBLs belong to Group 3(2).

The MBLs require one or more divalent cations, usually zinc, at the active site. The MBLs efficiently hydrolyse all beta lactams except azotrenam in vitro. The MBL activity blocking agents are EDTA, thiolcompounds and cupric chloride (CuCl2), ferrous chloride (FeCl2), etc. The MBLs are not inhibited by clavulanic acid, sulbactum and tazobactum.(3)

Acquired or transmissible MBLs can be plasmid, integron or transposon mediated. Thefirst MBL which was encoded on a plasmid, IMP-1 was discovered in Japan in 1988 (4). Since then, the IMP-1 to 23 and the VIM-1 to 14 variants have been reported (5).

Because of their high antibiotic resistance and potential for rapid and generalized dissemination to other Gram negative bacteria, the early recognition of MBL producers is the need of the hour. Though several phenotypic and genotypic methods are available, no Clinical Laboratory Standard Institute (CLSI) guideline is available for the detection of MBL producers (6).

Hence, the present study was undertaken to determine the prevalence of MBL producing
P.aeruginosa strains in our hospital and to evaluate an easy, cost effective and yet, specific phenotypic method for its detection.

Material and Methods

A total number of 140 Pseudomonas aeruginosa strains were isolated from different clinical specimens like pus and wound swabs, urine, sputum, blood, body fluids, endotracheal tube secretions, etc. in the Microbiology department and were identified as per the conventional methods (7).

The study was conducted from June 2008 to December 2009. The antibiotic sensitivity test was done by the disc diffusion method as per CLSI guidelines (8).

Screening of Imipenem resistant P.aeruginosa for carbapenem hydrolysis was done by The Hodge test (9) and the modified Hodge test (10). Hodge test positive and modified Hodge test positive P.aeruginosa strains were tested for MBL production by the double disk synergy test (DDST) (10) and the disk potentiation test (11).

Hodge Test (9)
In this test, lawn culture was done on a Muller Hinton agar (MHA) plate with overnight broth culture of E.coli ATCC 25922; the opacity was adjusted to 0.5 McFarland’s standard. Then, imipenem resistant P. aeruginosa (test strain) was inoculated by lawn culture on the same plate. A 10µg imipenem disc was placed in the centre of the plate. 10 µl of 50 mM zinc sulfate solution was added on the imipenem disk and the plates were incubated at 37şC overnight. The presence of a distorted zone of inhibition was interpreted as a positive result for carbapenem hydrolysis screening by the Hodge test.


The Modified Hodge Test (10)
The modified Hodge test (MHT) has been originally described by the Centre for Disease Control (CDC) for Carbapenemases detection in Enterobacteriaceae; but we have included this test for carbapenemase detection in P.aeruginosa, with slight modification.

Principle of MHT: When the test strain produces the enzyme carbapenemase, it allows the growth of a carbapenem susceptible strain (E.coli ATCC 25922) towards a carbapenem disk. The positive result is a characteristic clover-leaf indentation.

Procedure: In MHT, a lawn culture of 1:10 dilution of 0.5 McFarland’s standard E.coli ATCC 25922 broth was done on a Muller Hinton Agar plate. A 10 µg imipenem disk was placed in the centre of the plate and 10 µl of 50mM zinc sulfate solution was added to imipenem disk. Then, imipenem resistant P. aeruginosa (test strains) were streaked from the edge of the disk to the periphery of the plate in four different directions. After overnight incubation, the plates were observed for the presence of a ‘clover-leaf’ shaped zone of inhibition and the plates with such zones were interpreted as modified Hodge test positive.

The Double Disk Synergy Test (10)
An overnight broth culture of the test strain (opacity adjusted to 0.5 McFarland opacitystandard) was inoculated on an MH agar plate. After drying, a 10µg Imipenem disk and a blank filter paper disk (6mm in diameter, Whartman filter paper no.2) were placed 10mm apart from edge to edge. 10 µl of 50mM zinc sulfate solution was added to the 10 µg imipenem disk. Then, 10µl of 0.5 M EDTA (Sigma, USA) solution was applied to the blank filter paper disk. After overnight incubation, the presence of an enlarged zone of inhibition towards the EDTA disk was interpreted as DDST positive.

THE DISK POTENTIATION TEST (11)
A lawn culture of the test strain was done on Mueller Hinton (MH) agar plates (opacity adjusted to 0.5 McFarland’s standard). Two 10µg imipenem disks were placed on inoculated plates wide apart and 10 µl of 50mM zinc sulfate solution was added to each of the imipenem disks. Then, 5µl of 0.5M EDTA solution was added to one imipenem disk. After overnight incubation, an increase in zone size of ≥ 7mm around the Imipenem-EDTA disk as compared to the imipenem only disk was recorded as a positive result.

Results

Out of the 140 P. aeruginosa strains studied 18(12.9%) were imipenem resistant and 16(11.4%) were MBL producers [Table/ Fig 1], [Table/ Fig 2 ] 18 imipenem resistant strains were screened for carbapenem hydrolysis by the Hodge test and the modified Hodge test (MHT) [Table/ Fig 3], [Table/ Fig 4] 16(11.4%) were positive for carbapenem hydrolysis and were also positive for MBL production by the DDST and the disc potentiation tests [Table/ Fig 5].All (100%) P.aeruginosa strains were isolated from the indoor patients department (IPD) and 13(9.28%) were from the intensive care unit (ICU) patients. Out of 16 MBL producing P.aeruginosa strains, 8 (50%) were isolated from the Surgery ward, followed by 6 (37.5%) from the Medicine ICU department. Out of the 16 MBL producing P.aeruginosa strains, 7(43.8%) were isolated from pus and wound swabs and 6 (37.5%) were isolated from urine [Table/ Fig 6]. All 6(100%) MBL producing P.aeruginosa strains isolated from urine samples, were from catheterized patients as compared to 12(46.1%) out of the 26 non MBL producing P.aeruginosa strains.Except polymyxin B, 15 (93.7%) MBL producing P.aeruginosa strains were resistant to all the 11 antibiotics studied as compared to only 2 (1.6 %) non MBL producing P.aeruginosa strains [Table/ Fig 7]. The highest sensitivity patterns observed among non MBL producing P.aeruginosa were for polymyxin B, imipenem and amikacin. All 140 (100%) P. aeruginosa strains including 16 MBL producing strains were sensitive to polymyxin B.

Discussion

Pseudomonas aeruginosa strains are intrinsically resistant to various antimicrobial agents. MBL producing P.aeruginosa is an emerging threat and a cause of concern for treating physicians. MBL have the ability to confer broad spectrum β-lactam resistance for a wide variety of antimicrobial agents which include the third generation cephalosporins, cephamycins and carbapenems, gentamicins and fluoroquinolones. The MBLs have become more notorious as therapeutically available inhibitors are not available and for their potential for rapid and generalized dissemination to different Gram negative bacilli, e.g. P.aeruginosa, E.coli, Klebsiella pnemoniae, Acinetobacter spp., Shigella flexneri, etc.

Though PCR gives specific and accurate results, it’s use is limited to only a few laboratories because of it’s high cost and because of the different types of MBLs which are present worldwide(5).

In our study, we used the improved Hodge test with addition of 50mM of zinc sulfate on the imipenem disk as per Lee et al (9). Similarly, in the present study, the modified Hodge test, the double disk synergy test and the disc potentiation test were also improved by us, with the addition of 10 µl of 50mM zinc sulfate solution to the imipenem disks. By using this modification, the interpretation of the test results were found to be more clear-cut, as metallobetalactamases require divalent cations at the active site for their activation, usually zinc.

The results of the improved Hodge test were compared with those of the modified Hodge test (MHT). Though the results of the improved Hodge test and the Modified Hodge test were similar on MH agar plates, the interpretation of the MHT was quite easy and in a same MH plate, 4 different P. aeruginosa strains could be tested.

Arkawa et al recommended the testing of the ceftazidime-resistant isolates for MBL production, because in their study, some MBL producing Gram negative bacilli were inhibited by the low concentrations of imipenem and they were difficult to detect (12). But Lee et al reported that in their study, not a single MBL-producing isolate was detected among the imipenem susceptible isolates. (10).

Even in Japan, Sugino et al used only carbapenem resistant isolates for the screening of MBLs (13). Hence, we also used carbapenem resistant isolates for the detection of MBL. Though Arkawa et al and other authors have done the DDST and the Disc potentiation tests with ceftazidime and EDTA, in our study, we used imipenem and EDTA for the DDST and the Disc potentiation tests. As in our study, even in non MBL producing P.aeruginnosa strains, the ceftazidime resistance was quite high (78.2%). The MBL producing strains may also have another ceftazidime resistance mechanism (9). With such types of strains, DDST tests using an imipenem disc can show positive results for MBL, but a ceftazidime disc cannot; just as a cefepime disc but not a ceftazidime disc can detect extended spectrum β-lactamase (ESBL) production in Amp-C β-lactamase producing strains.
MBLs can hydrolyse all β-lactams except azotrenam in vitro (3) and therefore, we studied the utility of aztreonam (30μg) disc in MBL detection. Though Franklin et al have reported that 87% of their MBL producing Enteobacteriaceae isolates had >30 mm of zone with azotrenam, we did not find any MBL producing P.aeruginosa strain which was susceptible to azotrenam. This can only be explained by the fact that there is a presence of some other mechanisms for azotrenam resistance. Both a DDST and a disc potentiation test were also performed concurrently on a single MH plate.

In our study, the prevalence of MBL producing P. aeruginosa strains was 11.4%; which is similar to the studies conducted by Navneeth et al (12%) (14), Mendirattta et al (8.2%) (15), Hemlata et al (14%) (16) and Agrawal et al (8.05%) (17), respectively, from different parts of India.

In the present study, 2 imipenem resistant strains were found to be carbapenem hydrolysis negative by the Hodge test and MHT and the likely reason for the imipenem resistance may be a mechanism other than carbapenem hydrolysis, such as decreased membrane permeability (18).

As PCR can not be done in every laboratory, because of it’s high cost, the disc potentiation test for MBL detection should be introduced in any routine Microbiology laboratory for effective infection control and to prevent therapeutic failure. The Disc potentiation test is easy to perform, is cost effective and quite specific amongst other phenotypic methods which are used for MBL detection. The Disc potentiation test can also be done along with routine antibiotic sensitivity tests.

References

1.
Ambler R.P. The structure of β-lactamases. Philos Trans R Soc Lond B Biol Sci 1980; 289: 321-31.
2.
Bush K, Jacoby GA, Mederios AA. A functional classification scheme for β-lactamases and it’s correlation with molecular structure. Antimicrobial Agents Chemother1995; 39:1211-33.
3.
Walsh T R, M A Toleman, L. Poirel and P. Nordmann. Metallobetalactamases: the quiet before storm? Clin. Microbiol. Rev. 2005; 18: 306-25.
4.
Watanabe, M S Iyobe, M. Inove and S. Mitsuhashi. Transferable imipenem resistance in P.aeruginosa. Antimicrob Agent Chemother 1991; 35:147-151.
5.
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