Comparative Study of Antibiotics and Allium Sativum Against Coagulase Positive and Coagulase Negative Staphylococcus.

Garlic (Allium sativum) is a well known medicine used since ancient times. Its potency as an antibiotic without inducing drug resistance has been well documented. A very common pyogenic organism, namely Staphylococcus aureus, as well as its coagulase negative brethren, are very well known pathogens causing infections all over the world. Their ability to become multidrug resistant has become a matter of deep concern to medical personnels all over the world. We wanted to see that garlic, described in various literatures as antiviral, antibacterial, antifungal, antiprotozoal, antioxidant – held how much potency as an antistaphylococcal agent as well. Aims and Objectives: The study aimed at evaluating the antistaphylococcal activity of garlic, in the face of emergence of multidrug resistant forms of both coagulase positive and negative forms of staphylococcus. Materials and Methods: Raw garlic juice was extracted and was tested to be sterile. Pure cultures of coagulase positive and negative staphylococcus were prepared. A comparative study using six potent antibiotics as well as garlic against Staphylococcus and CoNS strains was done. At the same time, decreasing concentrations of garlic solution was used to show the effect on zone of inhibition. Discussion: Both S.aureus and CoNS strains showed significant inhibition by garlic extract. Garlic seemed to have greater antibacterial effect than all the antibiotics tested except linezolid, which persistently performed better. With decreasing concentration of garlic juice, zone of inhibition also decreased consistently.

Significance of Coagulase Negative Staphylococci with Special Reference to Species Differentiation and Antibiogram.

Coagulase negative staphylococci (CoNS)are part of normal human flora increasingly recognized as significant nosocomial pathogens, infection often associated with implanted devices, joint prosthesis and different indwelling devices, especially in very young, old immunocompromised patients. Aims: To identify CoNS species, their distribution and antibiotic susceptibility pattern from different clinical samples. Method: A total 185 CoNS isolates were collected from various clinical samples followed for species identification by a practical scheme adapted using simple ,useful test selected from various references. Antibiotic susceptibility done by Kirby Bauer disc diffusion method. Results: The study yield that 185 CoNS,strains were isolated out of 1514 positive cultures from various clinical specimens. Among species ; S. epidermidis was the most commonly isolated species (68.65%), followed by S. heamolyticus (16.75%),followed by S. saprophyticus(9.8%)and few other species also identified. The antibiotic susceptibility pattern against commonly used antibiotic showed multidrug resistance with more than 90% resistance to penicillin and no strains was resistance to vancomycin. The methicillin resistance was 63% among all isolates of CoNS. Conclusions: Study suggest increasing pathogenic potential of CoNS as well as emerging of drug resistance amongst them, that necessitates the need to adopt simple laboratory procedure to identify CoNS species and understand definitive therapy for CoNS isolates from various clinical samples. This scheme was able to identified 98.9% isolates up to species level.

Bacteriocins of indigenous clinical staphylococci: screening and charcterization

Staphylococcin [a class of bacteriocin] production was studied in 250 clinical isolates of staphylococci. 7% of the isolates exhibited intra - isolate and broad - range antagonistic activity. Crude bacteriocin preparations were not inactivated after prolonged thermal exposure [80°C] and were stable in the pH range of 5.4 - 10. The preparations also resisted the action of trypsin [a proteolytic enzyme], lysozyme [a glycolytic enzyme] and lipase [a lipolytic enzyme]. However, one of the extracts [Staphylococcin AB201] was sensitive to heat and trypsin. All the preparations retained their bioactivity after prolonged [16 weeks] refrigeration and freezing. Attempts to induce bacteriocin production [with UV, 0.5% mannitol and 2% yeast extract] and to elute cell bound bacteriocin [with 0.1M, 1M and 5M NaCl and 0.05M EDTA] were unsuccessful. The bacteriocinogenic determinants in the staphylococcal isolates were cured by heating [44°C] and ethidium bromide [300 micro g/mL], suggestive of their plasmid- borne location