Endotoxin Testing of Surgical and Cleanroom Gloves

Endotoxins are large molecules found in the outer membrane of Gram-negative bacteria. If enough of the molecules get into the bloodstream of humans or animals, they produce a variety of inflammatory responses. Symptoms range from fever and septic shock to low blood pressure and respiratory distress.

Gram-negative bacteria are ubiquitous – found in soil, water and living organisms – so avoiding them isn’t an option. Glove testing and manufacturing controls are employed to reduce the risk of transmission during surgery, whether from surgical gloves or other medical devices.

Endotoxin Testing

To lower the risk of infection and possible death, sterile medical gloves and some cleanroom gloves are tested for endotoxin contamination.

Horseshoe-CrabUSP Chapter <85> Bacterial Endotoxins Test. There are 3 methodologies to detect or quantify endotoxins in sterile medical and cleanroom gloves – Gel Clot, Turbidimetric and Chromogenic. All three methods utilize a reagent produced from the lysate of amoebocytes (white blood cells) of the horseshoe crab (Limulus polyphemus or Tachypleus tridentatus.) This test is often referred to as Limulus Amoebocyte Lysate or LAL.

The average contaminant concentration is reported in endotoxin units per device (glove pair.) The FDA has set a limit of 20 EU/device for medical devices that have direct or indirect contact with blood or lymph fluid. Devices that come into contact with cerebrospinal fluid have a much lower limit – 2.15 EU/device.

Contamination Control

To reduce the amount of contamination on their end product, medical device manufacturers need gloves with low endotoxin levels for their employees. Endotoxin contamination on gloves can vary.

In a 2007 study performed by the Malaysian Rubber Board, endotoxin contamination on latex surgical and examination gloves varied widely between brands. The non-sterile examination gloves tested ranged from <8.4 EU/glove pair to as high as 9,632 EU/glove pair. Most of the sterile surgical gloves in the study were generally clean, with most in the minor to moderate contamination range. A few, however, did test much higher than the FDA limit.

These potentially deadly, fragmented remains of bacteria are bioactive and difficult to kill. Endotoxins can adhere to medical implants and devices, even after sterilization.

Thus, endotoxin contamination control is an important part of medical device manufacturing. Glove manufacturers use a variety of technologies and environmental controls to reduce particulate and biological contamination. The most common approach is to package surgical and cleanroom gloves in a cleanroom environment or white room that is regularly cleaned and sanitized, and operated by workers that are gowned and gloved.

Although bacterial endotoxins are everywhere in our environment, thorough testing and diligent contamination control can result in safe medical devices that enhance our lives.


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