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Retroviridae
These are 80–100 nm, complex, enveloped, single-stranded RNA viruses. Retroviruses cause HIV (see Chapter 24 for more details).
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•
It is estimated that there are between 500 and 1000 different species of bacteria that inhabit the body.•
There are 50 species of bacteria that are known to cause infection or disease in humans.Others are opportunistic, causing infection when host immune defences are breached.
•
Bacteria are identified according to their shape, cell wall, Gram-stain reaction and virulence factors.•
The production of invasive enzymes helps the organism penetrate into the host’s tissues, causing tissue damage.•
The production and release of toxins are responsible for many of the signs and symptoms, or clinical features, of infection.•
Resistance to antibiotics, and virulence factors such as toxin genes, can be carried on plas- mids and transmitted between different strains of the same bacteria, or between different bacterial species.•
Viruses are the smallest known infective agents, approximately 100 to 1000 times smaller than the cells they infect.•
A virus is incapable of independent replication; it needs to access a host cell so that it can substitute its own nucleic acid for the cell’s DNA.•
Viruses are classified according to their shape, their capsid, their genetic material, the presence of a viral envelope, the host they affect (human, plant, animal or bacteria) and the effect which they have on the host.•
Once a host cell has been infected by a virus it bursts, releasing as many as 10 000 new virus particles which go on to infect other host cells.Further resources are available for this book, including interactive multiple choice questions. Visit the companion website at:
www.wiley.com/go/fundamentalsofinfectionprevention
Does an understanding of the virulence factors of bacteria and viruses, particularly those asso- ciated with the bacterial cell wall and toxin production, make healthcare staff more likely to appreciate and understand the importance of compliance with infection control standard precautions?
Reflection point
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References
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Contents
Fundamentals of Infection Prevention and Control: Theory and Practice, Second Edition. Debbie Weston.
© 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com/go/fundamentalsofinfectionprevention
The collection and
transportation of specimens
6
General points 81
Commonly requested
clinical specimens 86
Urine 86
Sputum 87
Wounds 88
Faeces 89
Rectal swabs 90
Throat swabs 90
Blood culture 90
Cerebral spinal fluid 93
Chapter summary: key points 93
References 94
Further reading 95
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Introduction
In order to accurately diagnose a patient’s infection and disease and prescribe the appropriate antimicrobial agent(s), the collection of the appropriate clinical specimen is essential. Unfortunately, many specimens received in the laboratory are substandard and therefore are not considered viable for a number of reasons that can, and should, easily be avoided. This chapter identifies the most commonly requested specimens that healthcare staff are required to collect for examination in the laboratory, and looks at the recommended methods of collection together with the health and safety issues that need to be taken into account to protect both the staff obtaining and transporting the specimen, and the laboratory staff who process it.
Learning outcomes
After reading this chapter, the reader will be able to: