Staphylococcus aureus transmission

Clements, A., Halton, K., Graves, N. et al. (2008) Overcrowding and understaffing in modern health-care systems key determinants in metidllin-resistant Staphylococcus aureus transmission. Lancet Infectious Diseases, 8(7), 427—434. 

Infections acquired from an external source are referred to as exogenous infections. These infections may occur as a result of human-to-human transmission, contact with exogenous bacterial populations in the environment, and animal contact. Resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. 

Methicillin- Transmission of resistant clones of bacteria from patient to patient resistant Staphylococcus aureus (MRSA)... 

The need for new antibiotics is driven by the recent rise in the incidence of resistance to commonly used antibiotics. The emergence of multiple-drug resistance to community-acquired infections, such as those caused by Streptococcus pneumoniae, is particularly alarming due to the ease of transmission [1-4], Recent reports show that methicillin-resistant Staphylococcus aureus, the common cause of hospital-acquired infections, has also moved into the community [5],... 

Seguin, J.C. Walker, R.D. Caron, J.P. Kloos, W.E. George, C.G. Holhs, R.J. Jones, R.N. Pfaller, M.A Methicillin-resistant Staphylococcus aureus outbreak in a veterinary teaching hospital potential human-to-animal transmission. J. Chn. Microbiol. 1999, 37, 1459-1463. 

Transmission of bacterial infection by transfusion to recipients of blood or blood components is a dreaded comphcation, but is rare when modern methods (that is closed systems) are used for the collection and preparation of blood components. Since the introduction of closed systems for blood collection and of stringent regulations regarding the storage of blood at 4 C, contamination of erythrocjde products has become very uncommon. However, platelets stored at room temperature are a potential source of bacterial infection, and there have been many reports of septic episodes associated with both erythrocyte and platelet concentrate transfusions (138). These reports suggest that such reactions may occur as often as 1 per 4000 platelet transfusions or even more often (139,140). In one study, bacterial isolates from contaminated platelets included Staphylococcus epidermidis. Staphylococcus aureus, and Bacillus cereus (141). 

Mastitis, an inflammatory reaction of the mammary gland, usually resulting from a microbial infection, is a widespread disease seen in cattle throughout the world. The major bacterial species that are responsible for bovine mastitis are Staphylococcus aureus. Streptococcus dysgalactiae, Streptococcus agalactiae, Streptococcus uberis, and E. coli. Of these, the first three cause a contagious route of transmission, whereas Streptococcus uberis and... 

The importance of the serial route in transmission of antibiotic-resistant staphylococci can be indirectly illustrated by findings in the environment, patients and the nursing personnel of a surgical clinic in Bratislava (Czechoslovakia) [8j. The results were obtained during corroborative studies on the distribution of resistant staphylococci from different environments in Slovakia [11]. The strains of coagulase-positive strains of Staphylococcus aureus from the clinic were tested for their sensitivity to six common antibiotics of that time. With staphylococci isolated from the environment, patients and the personnel, the percentages of resistance to benzylpeni-cillin, streptomycin, chlorotetracycline, erythromycin, chloramphenicol and vancomycin are shown in Fig. 6.1. The percentages of resistance to the individual antibiotics were positively correlated with the consumption of their preparations at the clinic. 

Fig. 1. Transmission electron micrographs showing sections of bacteria and host cells. (A) Digital image of methicillin-resistant Staphylococcus aureus within a primary human neutrophil. Bacterial capsular material (c) is preserved within the endosome. Cytoplasmic vesicles are evident in association with the endosomal membrane. (B) Photographic image of Borrelia burgdorferi and lymphocytes. In cross-section, two layers of extra membrane (arrows) are evident surrounding the spirochete (s) (unpublished data). Bars, 500 nm.

Outbreaks of bacterial infections in pork processing factories have shown that cuts on the skin made with bone were the most common port of entry of infection (Barnham and Kerby 1981). Streptococcus pyogenes and Staphylococcus aureus were the causative organisms. Nail-biting was suspected as one important cause of transmission of Staphylococcus aureus. Erythromycin-resistant Streptococcus pyogenes affected 46 of 194 workers in an outbreak that lasted 7 months (Sims and Riordan 1996). 

The role of the surgical gown is to improve patient safety but also to minimize the spread of infectious agents such as MRSA (MethiciUin-resistant Staphylococcus aureus) and other antibiotic-resistant bacterial strains, and hazards associated with the transmission of blood-borne pathogens (eg, human immunodeficiency virus (HIV), and Hepatitis B and C viruses) and many others, and thereby decrease the risk for staff as well as other patients to be contaminated by these infectious agents. 

According to the CDC, almost 1.7 million hospital-acquired infections (HAIs) occur yearly, contributing to approximately 99,000 deaths. Such infections were long accepted by clinicians as an inevitable hazard. Recent efforts demonstrate that simple measures can prevent the majority of common infections. Hospitals and providers must work to reduce the burden of these infections. Four specific infections account for more than 80 percent of all hospital-related infections. They are surgical site infections, catheter-associated urinary tract infections, central venous catheter-related bloodstream infections, and ventilator-associated pneumonia. Preventing the transmission of antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) remains an important infection control priority. Effective measures exist to prevent the most common healthcare-related infections. 

Sondi and Salopek-Sondi [6] have shown that silver NPs (12nm diameter) were an effective bactericide. Both, scanning and transmission electron microscopy (TEM) revealed that silver NPs damaged Escherichia coli cells by disrupting the cell wall, and subsequently accumulated in the bacterial membrane. The antimicrobial effects of silver NPs (13.5 nm) on microorganisms such as yeast, E. coli and Staphylococcus aureus were investigated by Kim et al. (7). 

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