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Gram Stain

This is a method (named after the Danish bacteriologist, Hans Christian Gram) for staining and identifying bacteria.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Gram Stains

The Gram stain test, developed in the 1800s by Hans Christian Gram, is a method for classifying different types of bacteria using a chemical stain and viewing through a microscope the results on the bacteria's protective cell wall.

Most bacteria are classified into two groups—Gram-positive or Gram-negative—depending on whether they retain a specific stain color.

Gram-positive bacteria retain a purple-colored stain, while Gram-negative bacteria appear pinkish or red. NIH - National Institute of Allergy and Infectious Diseases

What works? Research summarized

Evidence reviews

Antenatal Care: Routine Care for the Healthy Pregnant Woman

The original antenatal care guideline was published by NICE in 2003. Since then a number of important pieces of evidence have become available, particularly concerning gestational diabetes, haemoglobinopathy and ultrasound, so that the update was initiated. This update has also provided an opportunity to look at a number of aspects of antenatal care: the development of a method to assess women for whom additional care is necessary (the ‘antenatal assessment tool’), information giving to women, lifestyle (vitamin D supplementation, alcohol consumption), screening for the baby (use of ultrasound for gestational age assessment and screening for fetal abnormalities, methods for determining normal fetal growth, placenta praevia), and screening for the mother (haemoglobinopathy screening, gestational diabetes, pre-eclampsia and preterm labour, chlamydia).

Intrapartum Care: Care of Healthy Women and Their Babies During Childbirth

This guideline covers the care of healthy women in labour at term (37–42 weeks of gestation). About 600 000 women give birth in England and Wales each year, of whom about 40% are having their first baby. Most of these women are healthy and have a straightforward pregnancy. Almost 90% of women will give birth to a single baby after 37 weeks of pregnancy with the baby presenting head first. Most women (about two-thirds) go into labour spontaneously. Thus the majority of women giving birth in the UK fall under the scope of this guideline.

Type 1 Diabetes in Adults: National Clinical Guideline for Diagnosis and Management in Primary and Secondary Care

Type 1 diabetes can, if poorly controlled, produce devastating problems in both the short and the long term. Good control of blood glucose levels reduces the risk of these problems arising, but can be very difficult for patients and carers to achieve. This guideline emphasises that the NHS should provide all patients with the means – and the necessary understanding – to control their diabetes, and that it should help patients integrate the disease management with their other activities and goals. It argues that every person with diabetes should be able to develop their own care plan and utilise effective treatment in a way agreeable to them. The input of various health professionals may be needed to achieve this, and should be readily available. A system of regular monitoring, so that any complications which do develop are picked up at an early stage and treated appropriately, should also be provided.

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Summaries for consumers

The effects of antimicrobial treatment on bacterial vaginosis in non‐pregnant women  

Bacterial vaginosis (BV) is a very common cause of symptomatic and asymptomatic vaginal infection. It has been associated with a high incidence of obstetric and gynaecologic complications and an increased risk of transmission of HIV (human immunodeficiency virus). This review evaluated the effectiveness and adverse effects of antimicrobial agents used to treat BV in non‐pregnant women. Twenty‐four trials involving 4422 women were reviewed. With regard to less treatment failure, clindamycin was superior to placebo but comparable to metronidazole, irrespective of the dose regimen. Metronidazole tended to cause a higher rate of adverse events, such as metallic taste and nausea and vomiting, than did clindamycin. Oral lactobacillus combined with metronidazole was more effective than metronidazole alone. Administered in an intravaginal gelatin tablet, lactobacillus was also more effective than oral metronidazole. Triple sulfonamide cream was less effective compared with clindamycin. Hydrogen peroxide douche was not as effective as a single 2 g dose of metronidazole yet caused more harms. Only one trial involved asymptomatic women and the result was not conclusive. There was insufficient evidence to reach a conclusion on the effectiveness of other promising drugs. Drugs effective for bacterial vaginosis include clindamycin preparations, oral metronidazole, and oral and intravaginal tablets of lactobacillus. Adverse effects of metronidazole include metallic taste, and nausea and vomiting. Information on possible side effects of lactobacillus preparations is required.

Terms to know

A large group of single-cell microorganisms. Some cause infections and disease in animals and humans. The singular of bacteria is bacterium.
The basic subunit of any living organism; the simplest unit capable of independent life. Although there are some single-celled organisms, such as bacteria, most organisms consist of many cells that are specialized for particular functions.
Gram-negative Bacteria
Bacteria that show up as pink (negative) when treated by the gram-staining method.
Gram-positive Bacteria
Infections caused by bacteria that retain the crystal violet stain (positive) when treated by the gram-staining method.

More about Gram Stain

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Also called: Gram stain method, Gram staining method, Gram stain test

See Also: Bacterial Infections

Other terms to know: See all 4
Bacteria, Cells, Gram-negative Bacteria

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