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|Year : 2011 | Volume
| Issue : 3 | Page : 320--321
Department of Microbiology, Bhopal Memorial Hospital and Research Center, Karnod, Bhopal - 462 036, India
Department of Microbiology, Bhopal Memorial Hospital and Research Center, Karnod, Bhopal - 462 036
|How to cite this article:|
Desikan P. Snippets.Indian J Med Microbiol 2011;29:320-321
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Desikan P. Snippets. Indian J Med Microbiol [serial online] 2011 [cited 2020 Jan 24 ];29:320-321
Available from: http://www.ijmm.org/text.asp?2011/29/3/320/83927
With the rapid increase in prevalence of drug resistant microorganisms, the spectre of regression to the pre-antibiotic era looms large. To address this issue, on April 7, 2011, World Health Day, WHO introduced a six-point policy package to combat the spread of antimicrobial resistance. Available from: (http://www.who.int/world-health-day/2011/presskit/WHDIntrototobriefs.pdf). The package focuses on the need for national commitment and civil society engagement; enhancing surveillance and laboratory capacity; access to essential drugs; rational use of drugs, infection prevention and, last, but not the least, research and development. We hope that this will provide an impetus in the right direction for control of antibiotic resistance.
From 2006 to 2009, the SENTRY antimicrobial surveillance programme evaluated the antimicrobial activities of colistin and polymyxin B against a worldwide collection of 40-625 Gram negative bacilli (J Antimicrob Chemother 2011 Jun 29. [Epub ahead of print]). The polymyxins showed potent invitro activities (Minimum inhibitory concentration (MIC) ≤0.5-1 mg/L) against this large collection of clinical isolates, with very low resistance rates (<0.1%-1.5%). Although the polymyxins showed excellent in vitro activity against the vast majority of Gram negative bacilli evaluated, a trend to greater resistance was observed in the Asia-Pacific and Latin American regions.
However, the news is not so encouraging at home. Of a total of 337 blood culture isolates of Salmonella typhi isolated from Pondicherry, India, between January 2005 and December 2009, 74 (22%) were found to be multidrug resistant and 264 (78%) nalidixic acid resistant. About 8% of the isolates were ciprofloxacin resistant. All isolates with a ciprofloxacin MIC ≥4 mg/L possessed both double mutations in the QRDR of the gyrA gene and a single mutation in the parC gene. Active efflux pump mechanisms were found to be involved in ciprofloxacin resistance (Clin Microbiol Infect 2011 Apr 25. doi: 10.1111/j.1469-0691.2011.03546.x. [Epub ahead of print]).
In order to provide quantifiable evidence for the relationship between antimicrobial usage and surgical site infection (SSI), the antimicrobial homogeneity index (AHI), an indicator of prescription diversity, was examined in a retrospective study on 4510 patients who underwent lung, breast, and general surgery (J Infect Chemother 2011 Jun 28. [Epub ahead of print]). The study attempted to elucidate the correlation, if any, between AHI and antibiotic susceptibility in bacterial isolates from SSI. AHI showed a positive correlation coefficient (CC, P < 0.05) with susceptibility to ampicillin (CC = +0.327), cefotaxime (CC = +0.142), imipenem/cilastatin (CC = +0.101), and sulbactam/cefoperazone (CC = +0.145), and was found to be associated with increased susceptibility in microbes isolated from SSI. Other factors that significantly influenced the incidence of SSI included operative time, endoscopy and age of the patients.
The high rates of antibiotic prescriptions and antimicrobial resistance in France motivated its participation in the European e-Bug school project regarding microbes and infection transmission, prevention and treatment. The project aims at raising awareness about infection among children, helping them to adopt suitable attitudes and behaviour towards infection transmission and treatment. Background research showed that the subject matter was best suited to the national science curricula of the fourth and fifth forms in junior schools, and the sixth and ninth forms in senior schools. The e-Bug Project was launched through a national institutional implementation plan in September 2009 and orders for e-Bug tools increased rapidly. By the end of October, 57% of all senior science teachers and 16% of all junior school teachers had ordered the pack. The collaboration with both educational and health partners was particularly helpful in implementation of the project (J Antimicrob Chemother 2011 Jun;66 Suppl 5:v67-v70).
A study investigated the hypothesis that MRSA isolates with reduced susceptibilities to daptomycin (DAP) - a calcium-dependent molecule acting as a cationic antimicrobial peptide [CAP] - may also co-evolve reduced invitro susceptibilities to host defense cationic antimicrobial peptides (HDPs). Ten isogenic pairs of clinical Methicillin resistant staphylococcus aureus (MRSA) DAP-susceptible/DAP-resistant (DAP-S/DAP-R) strains were tested against two distinct HDPs differing in structure, mechanism of action, and origin (Antimicrob Agents Chemother 2011 Jun 27. [Epub ahead of print]) . DAP-R strains exhibited: (i) significantly reduced susceptibility to killing by all three peptides (P < 0.05); (ii) increased cell membrane fluidity; and (iii) significantly thicker cell walls (P < 0.0001), suggesting that adaptive mechanisms involved in the evolution of DAP-R also provide MRSA with enhanced survivability vs. HDPs. As if drug resistance alone was not bad enough!
To assess the presence of multidrug-resistant (MDR) Salmonella with human clinical relevance in pig farms, 79 samples were collected from the farms and analysed for the presence of MDR Salmonella (J Antimicrob Chemother 2011 Jun 22. [Epub ahead of print]). Sixty Salmonella isolates were recovered from five samples (two manure, two waste lagoons and one animal feed). All isolates were resistant to at least one antibiotic (tetracycline) and 97% to at least four antibiotics from different families. Diverse resistance genes and integrons were detected in the isolates. The survival of these strains in manure and waste lagoons is of concern, since these environments might allow spread of MDR bacteria beyond the boundaries of pig farms.
Tuberculosis (TB) remains an important global public health problem and drug resistance has only compounded the problem. Although several gene mutations in specific loci of the Mycobacteria tuberculosis genome have been reported as the basis for drug resistance, additional resistance mechanisms are now believed to exist. Bioinformatics as well as direct and indirect evidence have established relationships among drug efflux with intrinsic or acquired resistance in M. tuberculosis. In fact, M. tuberculosis presents one of the largest numbers of putative drug efflux pumps compared to its genome size (FEMS Immunol Med Microbiol 2011 Jun 10. doi: 10.1111/j.1574-695X.2011.00831.x. [Epub ahead of print]).
One of the ways of tackling the effects of widespread antimicrobial resistance is development of new antimicrobials. The bad news, however, is that there are almost no new antibiotics in the pipeline. The dwindling supply of new antibiotics largely reflects regulatory and commercial challenges, and also a failure of discovery. In the 1990s, the pharmaceutical industry abandoned its classical ways of seeking antibiotics and attempted to use a strategy that combined genomics with high-throughput screening of existing compound libraries. With too much emphasis on identifying targets and molecules that bind to them, and too little emphasis on the ability of these molecules to permeate bacteria, evade efflux and avoid mutational resistance, no molecule found by this strategy has yet entered clinical use. As a result, many major pharmaceutical companies have abandoned attempts at antibiotic discovery. However, some new ventures variously financed by venture capital, charity or public money are now beginning to find new antibiotic compounds, some of them very promising invitro or in early trials. Be that as it may, their development through Phase III still depends on financial commitments from large pharmaceutical companies (J Antimicrob Chemother 2011 Jun 23. [Epub ahead of print]).
Keeping this bleak situation in mind, the center for disease control and prevention (CDC) has put up a federal register notice with a request for review of, and comment on, the draft document titled "A Public Health Action Plan to Combat Antimicrobial Resistance". Available from: http://www.cdc.gov/drugresistance/pdf/2010/Interagency-Action-Plan-PreClearance-03-2011.pdf. All comments can be viewed at CDC's public comments page at http://wwwn.cdc.gov/publiccomments/.