Psuedomonas Aeruginosa Pseudomonas Aeruginosa Epidemiology

SAMPLE EXCERPT:

101-104, 137-138). Most patients will present with a moderate to high fever and 50% will be hypotensive. Skin manifestations may be present and include papules, blisters, diffuse rash, and ecthyma gangresnosum (flat, ulcerating pustules). Patients may appear sleepy and confused, sweating, agitated, or weak. It is important to note, however, that symptoms will vary depending on the tissues and organs primarily affected. For example, patients suffering from infective endocarditis will present with leukocytosis, anemia, thrombocytopenia, and azotemia, in 40%, 60%, 30%, and 40-50% of patients, respectively, and two thirds of these patients will have an abnormal X-ray.

The most common locations for P. aeruginosa infections are the blood, heart, lungs, urinary tract, central nervous system, bones and joints, skin and soft tissues, eyes, ears, and gut (Baltch and Smith, 1994). The lungs are particularly susceptible in patients suffering from cystic fibrosis.

Diagnosis

A definitive diagnosis of a P. aeruginosa infection depends on the results of laboratory tests (Baltch and Smith, 1994, p. 104). For example, if an adult patient undergoing chemotherapy for colon cancer presents with a fever and chills, and bacteremia is suspected, then blood samples are cultured. Preferably, two to three blood samples, separated by about an hour, are taken before the patient is started on antibiotics (Vandepitte et al., 2003, p. 20-23). If the patient is already on antibiotics, the anticoagulant sodium polyanethol sulfonate can be added to the blood sample. The blood sample, typically 10 ml, is then diluted with 100 ml of blood broth to dilute any antibiotics and phagocytic immune cells. This is added to culture bottle and incubated for 7 or more days.

If growth is observed, then a sample is taken and examined under a microscope and tested with a Gram stain (Vandepitte et al., 2003, p. 23-25). Gram-negative, rod shaped microorganisms, such as P. aeruginosa (Figure 1) would be streaked onto blood agar, MacConkey agar, Kligler iron agar, motility indole-urease (MIU) medium, and Simmons citrate agar. P. aeruginosa should grow well on blood agar. Positive identification begins by picking a colony and culturing it on cetrimide agar supplemented with nalidixic acid (Hawkey and Kerr, 2004, p. 338). This growth media is selective for P. aeruginosa. Positive cultures are blue/green under normal light, or rarely pink/maroon. Under ultraviolet light, the cultures will fluoresce yellow. The initial identification of the species by culture is usually confirmed through one or more typing methods, which can distinguish between different strains of P. aeruginosa (Botzenhart and Doring, 1993, p. 8). The most common typing method for P. aeruginosa is serotyping, which involves the use of antisera to identify different strains of P. aeruginosa (Hawkey and Kerr, 2004, p. 344-345).

Figure 1: P. aeruginosa stained with Gram stain.

Treatment

The planktonic form of P. aeruginosa is readily cleared with first line antibiotics; however, once the chronic form of the disease has been established, there is no known effective treatment for clearing this pathogen from immune-compromised or cystic fibrosis patients (Hurley, Camara, and Smyth, 2012).

Prevention

Since the primary route of exposure to P. aeruginosa is through medical clinics and hospitals, sanitation is paramount to limiting its prevalence (Baltch and Smith, 1994, p. 52-65). Since person to person contact is the primary source of nosocomial microbes, routine sanitation measures, such as hand washing and antimicrobial agent use, are generally recommended to minimize exposure to all nosocomial microbes. However, hemodialysis units, intensive care units, nebulizers, catheters, and flower vases with water can be significant and dangerous sources of nosocomial microbes. For this reason, scheduled surveillance of these sources is recommended. Patients suffering from P. aeruginosa infections need not be isolated, unless they have open, infected wounds that cannot be covered adequately, such as burn patients.

References

Baltch, A.L. And Smith, R.P. (Eds.). (1994). Pseudomonoas aeruginosa Infections and Treatment. New York, NY: Marcel Dekker, Inc.

Botzenhart, Konrad and Doring, Gerd. (1993). Ecology and Epidemiology of Pseudomonas aeruginosa. In M. Campa, M. Bendinelli, H. Friedman (Eds.), Pseudomonas aeruginosa as an Opportunistic Pathogen (pp. 1-18). New York, NY: Plenum Press.

Hawkey, Peter M. And Kerr, Kevin G. (2004). Laboratory investigation of health care-associated infection. In P. Hawkey and D. Lewis (Eds.), Medical Bacteriology: A Practical Approach (pp. 331-354). Oxford, UK: Oxford University Press.

Hurley, Matthew N., Camara, Miguel, and Smyth, Alan R. (2012). Novel approaches to the treatment of Pseudomonas aeruginosa infections in cystic fibrosis. European Respiratory Journal, published online ahead of print, 1-19. Retrieved 23 July 2012 from http://erj.ersjournals.com/content/early/2012/06/27/09031936.00042012.long.

Van Delden, Christian and Iglewski, Barbara H. (1998).…