Topic: Culture

Last updated: February 27, 2019

Gram –negative bacteria are group of bacteria that do not retain crystal violet stain used gram-staining method of bacteria differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall, sandwiched between an inner cytoplasmic cell membrane and a bacteria outer membrane.

Gram negative bacteria can be red or pink in colour with the used of gram staining reagents (Madigan et al., 2009) Gram negative bacteria are found everywhere, in virtually all environments on earth that support life. The gram-negative include the model organism Escherichia coli, as well as many pathogenic bacteria, such as Pseudomonas aeruginosa, Neisseris gonorrhoeae, and Chlamydia trachomatis.

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They are an important medical challenge, as their outer membrane protects them from many antibiotics (including penicillin). A component can cause a toxic reaction when bacteria lysed by immune cells. This toxic reaction can include fever, an increased respiratory rate, and low blood pressure- life threatening condition known as septic shock. Several classes of antibiotics have been designed to gram-negative bacteria specifically, including aminoglycoside and carbapenems.Gram negative-bacteria display certain characteristics:• An inner cell membrane is present• Porin exist in the outer membrane, which act like pores for a particular molecule• A thin peptidoglycan layer is present (This is much thicker in gram-positive bacteria)• Has outer membrane containing lipopolysaccharides in its outer leaflet and phospholipids in the inner leaflet.

• If present, flagella have four supporting rings instead of two• Lipoproteins are attached to the polysaccharide backbone.The word Pseudomonas is the combination of two word i.e. the Greek and Latin word which means ”false unit” (pseudo=false, Greek; Monas= single unit, Latin). For unicellular organism “Monas” had been used in initial history of microbiology. In 1786, Otto Friedrich Muller, from Copenhagen, who had describe Pseudomonas, who had found into the group of vibriones ( which was defined as group of shaking bacteria) after many years later, Pseudomonas were found to be involved in motility. Therefore the assigned the name of “Pseudo”, because due to shaking in nature and also it shows motility. Pseudomonas was found to be mostly present in water, identified as important microorganism.

Pseudomonas aeruginosa is one of the main causes of hospital-acquired as well as community-acquired Infections ( Lambert et al., 2002). Pseudomonas aeruginosa is an aerobic, motile, Gram-negative rod that belongs to the family, Pseudomonadeceae.

(Samat et al., 2009). It is 1-5µm long and 0.5-1.0µm wide.

Pseudomonas aeroginosa is an obligate bacterium, means they can survive in presence and absence of oxygen. Pseudomonas aeroginosa has a great role to play in degradation; it degrades organic compounds such as benzoate. The can survive in some harsh environment like in disinfectant solutions and also in nutrient and also in nutrient deficient condition. They use oligotrophic which contain more dissolve oxygen as compared to plant.Pseudomonas aeroginosa play an important role in degradation of wastes and organic matter due to presence of plasmid. They can cause many infections such as critical illness and hospitalized infection as seen in many hospitalized individuals. It is an opportunistic pathogen, meaning that it exploits some break in the host defenses to initiate an infection.

It is one of the important bacterial pathogens that are isolated from various samples. Despite advances in medical and surgical care and introduction of wide variety of antimicrobial agents having anti-pseudomonal activities, life-threatening infection caused by P. aeruginosa continues to cause complications in hospital-acquired infections (Govind et al., 2012).

When penicillin was first discovered it was used for the treatment and was seen as magic drugs. A single injection of penicillin could cure a life-threatening infection. Unfortunately, with time due to malpractices of natural causes, most of the cheaper antibiotics have lost their efficacy, as a result of more expensive and complicated antibiotics which was introduced and marketed to combat simple infection (Bett et al.

, 2007). The microbial pathogens, as well as their antibiotic sensitivity pattern, may change from time to time and place to place. Therefore, knowledge of current drug resistance pattern of the common pathogenic bacteria in a particular region is useful in clinical practice. Recently P.

aeruginosa demonstrates resistance to multiple antibiotics; thereby jeopardizing the selection of appropriate treatment. The heightened level of drug resistance is a result of the de novo emergence of resistance in a specific organism after the exposure to antimicrobials as well as patient to patient spread of resistant organism (Aloush et al., 2006).

P. aeruginosa can be found in most environments including soil, water and various types of vegetation. P. aerogunosa in a culture can produce multiply colony types, the may also differ in biochemical and enzymatic activities and different antimicrobial susceptibility pattern. The grow well at 37-42°C. In hospital environment, for examples, it has be isolated from drains, sinks, faucets, water from flower, cleaning solutions, medicine and sometimes disinfectant soap solution. It does not ferment carbohydrates, but many strains oxidize glucose. The organism is a clinically important pathogen responsible for a variety of systemic infections such as urinary tract infections, respiratory system infections, gastrointestinal infections, dermatitis, bacteremia, soft tissue infections, bone and joint infections,( Nasreen et al.

, 2015). P. aeruginosa causes infection in immunocompromised patients such as those suffering from


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