{"id":479,"date":"2015-01-22T07:20:36","date_gmt":"2015-01-22T07:20:36","guid":{"rendered":"http:\/\/biomedpharmajournal.org\/?p=479"},"modified":"2018-10-06T04:43:03","modified_gmt":"2018-10-06T04:43:03","slug":"in-vitro-microbial-efficacy-analysis-of-tobracef-a-fixed-dose-combination-of-ceftazidime-and-tobramycin-against-acinetobacter-lwoffii-morganella-morganii-enterobacter-cloacae-hafnia-alvei-citroba","status":"publish","type":"post","link":"https:\/\/biomedpharmajournal.org\/staging\/vol1no2\/in-vitro-microbial-efficacy-analysis-of-tobracef-a-fixed-dose-combination-of-ceftazidime-and-tobramycin-against-acinetobacter-lwoffii-morganella-morganii-enterobacter-cloacae-hafnia-alvei-citroba\/","title":{"rendered":"In Vitro Microbial Efficacy Analysis of Tobracef, a Fixed Dose Combination of Ceftazidime and Tobramycin Against Acinetobacter lwoffii, Morganella Morganii, Enterobacter Cloacae, Hafnia Alvei, Citrobacter Freundii & Serratia Grimesii."},"content":{"rendered":"

Introduction<\/strong><\/p>\n

Ceftazidime belongs to cephalosporin class of antibiotics with broad spectrum activity.1, 2<\/sup> It is stable to both plasmid and chromosomal \u03b2 – lactamase resistance\u00a0 then other cephalosporins.3, 4 <\/sup>Ceftazidime is a third generation cephalosporin and is resistant to hydrolysis.\u00a0 It is effective against a broad range of gram positive and gram negative bacteria and also against bacteria resistant to cephalosporins.<\/p>\n

Tobramycin is an aminoglycoside antibiotic used to treat various types of bacterial infections, particularly gram\u00a0 negative infections. It\u00a0 is often used concomitantly with other antibacterials to extend its spectrum of efficacy or increases its effectiveness. Treatment with a combination of an aminoglycoside\u00a0 with\u00a0 a\u00a0 \u03b2 – lactam has showed\u00a0 increased efficacy.<\/p>\n

Combination therapy of cephalosporins and aminoglycosides is also used to broaden the antimicrobial spectrum in critically ill patients while awaiting a bacteriological diagnosis or\u00a0 proven polymicrobial infection. Synergism appears to be maintained even at very\u00a0 high\u00a0 MIC\u00a0 with drug\u00a0 combinations within achievable therapeutic ranges.5, 6, 7, 8<\/sup><\/p>\n

Ceftazidime and tobramycin combination therapy is considered by some clinicians to be the clinical standard.[9]<\/sup> Antibacterial drugs have been highly successful in controlling the morbidity and mortality that accompany serious bacterial infections. Some of the exiting antibiotics may cause adverse effects in some patients. Some of\u00a0 these side effect\u00a0 may be significant enough to require that therapy should be discontinued.10, 11<\/sup><\/p>\n

The fight against bacterial infection represents one of the highest point of the modern medicine. Since the development of\u00a0 antibiotics, this powerful tool has saved millions of\u00a0 lives. However, because of inappropriate and large use of antibiotics, many antibiotic resistant strains are growing in number. The resistant bacteria\u00a0 pose a significant threat to human health and a challenge to researches12, 13 <\/sup>Keeping this in the view, the present study was planned\u00a0 to evaluate efficacy\u00a0 of\u00a0 tobracef, FDC of ceftazidime and tobramycin against some clinically significant microorganisms.<\/p>\n

Materials and Methods<\/strong><\/p>\n

Bacterial Strains<\/strong><\/p>\n

Following strains obtained from Microbial Type Collection Center of Institute of Microbial Technology, Chandigarh, India were\u00a0 used for the study:<\/p>\n

Acinetobacter lwoffii <\/em>(MTCC No. 496), <\/em>Morganella\u00a0 morganii <\/em>(MTCC No. 662 ), <\/em>Enterobacter cloacae <\/em>(MTCC No. 509), <\/em>Hafnia alvei <\/em>(MTCC No. 1426), <\/em>Citrobacter freundii <\/em>(MTCC No. 1658)\u00a0 and\u00a0 <\/em>Serratia grimesii <\/em>(MTCC No. 1887).<\/em><\/p>\n

Antibiotic<\/strong><\/p>\n

Tobracef, ceftazidime and tobramycin used in study were provided by manufacturer, Venus Remedies Limited, India.<\/p>\n

Medium<\/strong><\/p>\n

Mueller- Hinton (MH) media supplemented with calcium (25 mg\/l) and Magnesium (1.25 mg\/l) was used for MIC and susceptibility tests experiments. Colony counts were determined with MH agar plates.<\/p>\n

Susceptibility Testing<\/strong><\/p>\n

The MIC of ceftazidime and tobramycin alone and in a Tobracef against A. <\/em>lwoffii,<\/em> M. morganii, E. cloacae, H. alvei, C. freundii\u00a0 <\/em>and\u00a0 <\/em>S.<\/em> grimesii<\/em> were determined by broth micro dilution method as per the standard National Committee for Clinical Laboratory Standards.14<\/sup> Overnight MH broth cultures were used to prepare inocula of\u00a0 105\u00a0 <\/sup>CFU\/ml. The MIC was defined as the lowest concentration of antimicrobial\u00a0 agent that prevented\u00a0 turbidity after 24 h of\u00a0 incubation at 37 0<\/sup>C.<\/p>\n

Results<\/strong><\/p>\n

MIC studies<\/strong><\/p>\n

In case\u00a0 of A. <\/em>lwoffii,<\/em> M. morganii, E. cloacae, H. alvei, C. freundii\u00a0 <\/em>and\u00a0 <\/em>S.<\/em> grimesii<\/em>\u00a0 <\/em>MIC were found to be 8 \u00b5g\/l, 4 \u00b5g\/l, 16 \u00b5g\/l 4 \u00b5g\/l 2 \u00b5g\/l and 1 \u00b5g\/l for ceftazidime respectively. In\u00a0 a\u00a0 tobramycin\u00a0 alone the\u00a0 MIC\u00a0 was found to be\u00a0 4 \u00b5g\/l, 8 \u00b5g\/l, 8 \u00b5g\/l 8 \u00b5g\/l 4 \u00b5g\/l and 8 \u00b5g\/l\u00a0 respectively and Tobracef \u00a0MIC was found to be 2 \u00b5g\/l, 2 \u00b5g\/l, 4 \u00b5g\/l, 2 \u00b5g\/l, 1 \u00b5g\/l and 0.5 \u00b5g\/l.<\/p>\n

The MIC of all microbial strains under study resulted in significant reduction in ceftazidime, tobramycin\u00a0 alone\u00a0 and Tobracef. (Table-1)<\/p>\n

Table 1: Minimum Inhibitory Concentrations determination of ceftazidime, tobramycin\u00a0 and Tobracef<\/em> with\u00a0 A<\/em>. lwoffii, M. morganii,\u00a0 E. cloacae, H. alvei, C. freundii\u00a0 <\/em>and S. grimesii.<\/em><\/strong><\/p>\n\n\n\n\n\n\n\n\n\n
S. No.<\/strong><\/td>\nMicroorganism<\/strong><\/td>\nDrug [mg\/L]<\/strong><\/td>\n\u00a0MIC Concentration (mg\/L)<\/strong><\/td>\n<\/tr>\n
1<\/td>\nA<\/em>. lwoffii<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

8<\/p>\n

4<\/p>\n

2<\/td>\n<\/tr>\n

2<\/td>\nM<\/em>. morganii.<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

4<\/p>\n

8<\/p>\n

2<\/td>\n<\/tr>\n

3<\/td>\nE<\/em>.<\/em> cloacae.<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

16<\/p>\n

8<\/p>\n

4<\/td>\n<\/tr>\n

4<\/td>\nH<\/em>. alvei.<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

4<\/p>\n

8<\/p>\n

2<\/td>\n<\/tr>\n

5<\/td>\nC<\/em>. freundii.<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

2<\/p>\n

4<\/p>\n

1<\/td>\n<\/tr>\n

6<\/td>\nS<\/em>. grimesii<\/em><\/td>\nCeftazidime<\/p>\n

Tobramycin<\/p>\n

Tobracef<\/em><\/td>\n

1<\/p>\n

 <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

MIC of \u00a0all microbial strain under study resulted in reduction in Tobracef when compared with ceftazidime and tobramycin alone. (Table – 2).<\/p>\n

Table 2 ;Results of comparative Antimicrobial Susceptibility Test\u00a0 studies of ceftazidime,\u00a0 tobramycin and Tobracef<\/em>.<\/strong><\/p>\n\n\n\n\n\n\n\n\n\n\n
S. No.<\/strong><\/td>\nMicroorganism<\/strong><\/td>\nZone diameter Inhibition (mm)<\/strong><\/td>\n<\/tr>\n
Ceftazidime (30 \u00b5g)<\/strong><\/p>\n

Avg.\u00b1 S.D.<\/strong><\/td>\n

Tobramycin (10\u00b5g)<\/strong><\/p>\n

Avg.\u00b1 S.D.<\/strong><\/td>\n

Tobracef\u00a0 <\/em>(40\u00b5g)<\/strong><\/p>\n

Avg.\u00b1 S.D.<\/strong><\/td>\n<\/tr>\n

1<\/td>\nA. lwoffii<\/em><\/td>\n23.80 \u00b1 0.58<\/td>\n26.74 \u00b1 0.87<\/td>\n28.07 \u00b1 0.34<\/td>\n<\/tr>\n
2<\/td>\nM. morganii<\/em><\/td>\n27.14 \u00b1 0.40<\/td>\n23.30 \u00b1 0.99<\/td>\n28.34\u00b1 0.89<\/td>\n<\/tr>\n
3<\/td>\nE. cloacae<\/em><\/td>\n27.83 \u00b1 0.12<\/td>\n22.08 \u00b1 1.06<\/td>\n23.24 \u00b1 0.65<\/td>\n<\/tr>\n
4<\/td>\nH. alvei<\/em><\/td>\n25.82 \u00b1 0.19<\/td>\n25.12 \u00b1 0.43<\/td>\n29.77\u00b1 0.63<\/td>\n<\/tr>\n
5<\/td>\nC. freundii<\/em><\/td>\n27.71 \u00b1 0.22<\/td>\n26.80 \u00b1 0.40<\/td>\n29.41 \u00b1 1.48<\/td>\n<\/tr>\n
6<\/td>\nS. grimesii<\/em><\/td>\n33.68 \u00b1 0.39<\/td>\n22.74 \u00b1 0.10<\/td>\n35.86 \u00b1 0.05<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Average <\/strong>\u00b1 \u00a0standard deviation <\/strong><\/p>\n

Susceptibility studies<\/strong><\/p>\n

 <\/p>\n

Discussion <\/strong><\/p>\n

A synergistic interaction between the two antibiotics is one reason for using this combination.15 <\/sup>A further indication for antibiotic combinations is to prevent emergence of resistance.16 <\/sup>Antibiotic combinations have long been used to provide antibacterial activity against\u00a0 multiple potential pathogen for initial empirical treatment of critically ill patients. Several studies of antibiotic combination therapy\u00a0 for gram\u00a0 negative infection conducted from the 1970s\u00a0 to the 1990s. The consensus\u00a0 is that combination therapy is probably more effective than mono therapy only for infections. Gram negative bacterial species typically have a higher degree of antibiotic resistance than gram positive bacteria. This is largely in part due to the presence of a selectively permeable outer membrane which restricts the entrance of small hydrophobic molecules, including many available antibiotics.17\u00a0 <\/sup>Aminoglycoside class antibiotic exert a killing effect by binding to bacterial ribosomes and inhibiting bacterial protein synthesis.<\/p>\n

Useful antibiotic classes based\u00a0 on\u00a0 a\u00a0 \u03b2 – lactam structure include broad\u00a0 penicillins, cephalosporins, carbapenems, all of which inhibit bacterial cell wall synthesis. \u03b2 – lactamase enzymes that rapidly degrade the cephalosporins\u00a0 \u03b2 – lactam ring have a primary bacterial resistance mechanism against this class of drug since the commencement of clinical cephalosporins use in the 1940s. Because of\u00a0 this, most cephalosporins derived antibiotics still clinically used\u00a0 are formulated to include a\u00a0 \u03b2 – lactamase\u00a0 inhibitor\u00a0 in order to increase the drug’s effectiveness. Cephalosporins also contain a\u00a0 \u03b2 – lactam ring, but are structurally more resistance\u00a0 to\u00a0 \u03b2 – lactamase\u00a0 degradation.<\/p>\n

Ceftazidime is a third generation cephalosporins, with good antibacterial activity.2, 18 <\/sup>Clinically administration of two or more antibiotics in the treatment of infections is usually rationalized with the knowledge that multiple antibiotics often exert additive or synergistic effects, increasing the likelihood of pathogen eradication. In comparison with older cephalosporins, it crosses the bacterial outer cell membrane faster and has advantages of rapid penetration in periplasmic space as well as of extended spectrum of the activity that include gram positive and gram negative organisms.<\/p>\n

Tobracef has lower MIC than ceftazidime and tobramycin alone against A. <\/em>lwoffii,<\/em> M. morganii, E. cloacae, H. alvei, C. freundii <\/em>and S.<\/em> grimesii<\/em>. <\/em>AST studies also showed\u00a0 that\u00a0 bacterial\u00a0\u00a0 lytic zone was more under influence of\u00a0 Tobracef\u00a0\u00a0 than\u00a0 ceftazidime and tobramycin alone.<\/p>\n

This investigation indicated that Tobracef has better efficacy as compared to ceftazidime and tobramycin alone\u00a0 in organisms under\u00a0 study.<\/p>\n

References<\/strong><\/p>\n

    \n
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