Bacteriology of Abscesses with Special Reference to Phenotyping and Genotyping of Methicillin Resistant Staphylococcus Aureus in Govt Stanley Medical College and Hospital, Chennai.
INTRODUCTION :
An abscess is a localized collection of purulent inflammatory tissue caused by
Suppuration deep within a tissue, an organ or a confined space. It is produced by deep seeding
of pyogenic bacteria into a tissue. It may involve skin, dermis, fasciae, muscles, and even
bones. They occur in many parts of the body as superficial infections or as deep-seated
Infections associated with any internal organ. Any organism isolated from them may be of
Significance. Abscesses that develop as a result of introduction of the normal flora into a normally
sterile body site are often polymicrobial in nature Flora can gain access to the sterile site by
direct extension or secondary to laceration or perforation. Because of the uniqueness of the
Normal flora at various body sites, the microbiology of such abscesses is generally predictable
by their location.
Organisms may enter the tissue by direct implantation (eg, penetrating trauma with a
Contaminated object); spread from an established, contiguous infection; dissemination via
Lymphatic or hematogenous routes from a distant site; or migration from a location where there
are resident flora into an adjacent, normally sterile area because of disruption of natural barriers.
AIMS AND OBJECTIVES ;
• To study the prevalence of aerobes and anaerobes in abscess.
• To characterize the aerobes and anaerobes.
• Phenotypic and Genotypic characterization of antibiotic susceptibility of isolated organism.
• To study the incidence of methicillin resistant Stapylococcus aureus among the isolate.
• To monitor antibiotic sensitivity pattern of MRSA and to formulate
definite antibiotic policy to reduce the incidence of MRSA infection.
CONCLUSION :
Among 120 cases of superficial and deep abscesses studied for
bacteriological profile showed 134 isolates, of which 88.33% were
monomicrobial and 11.67% were polymicrobial. Of 76.87% aerobic isolates,
44.77% were gram positive cocci and 32.09% were gram negative bacilli. Of
23.14% anaerobic isolates , 14.18% were gram positive cocci and 8.96%were
gram negative bacilli.
Of 134 isolates, Staphylococcus aureus was predominant isolate
(41.04%) from both superficial and deep abscess, of which 36.36% were
detected as Methicillin resistant .MRSA emerge to be significant problematic
pathogen in the surgical settting with vancomycin probably the only reliable
choice of this infection. The conventional phenotypic methods ,Cefoxitin disc
diffusion method and Oxacillin screen agar had high degree of sensitivity and
specificity, in concordance with ‘gold standard’ mecA gene detection by
polymerase chain reaction.
Essential infection control practices should include hand washing by
hospital personnel, basic cleaning of all surface levels (hand touch sites) ,
increased barrier precautions and isolation of patients colonized or infected
with MRSA.. A multidisciplinary approach, coordinated participation of
microbiologists, clinicians, nursing personnel, hospital infection control team is
necessary for management of MRSA producing infection. Continuous
monitoring of antimicrobial susceptibility pattern in individual settings together
with judicious use is emphasized to minimize emergence of drug resistant
bacteria
