In the medical laundry environment, the washing of medical textiles is a crucial part of hospital infection control. However, due to shortcomings in equipment design, operational procedures, and disinfection effectiveness, medical laundries still face a high risk of bacterial contamination. The following is an analysis of the common types of bacteria and their contamination in medical laundry environments, along with a discussion of their relationship to the Chinese standard WS/T508.

I. Common Types of Bacteria and Their Contamination

(1) Bacteria

• Escherichia coli

E. coli is a common intestinal bacterium, often contaminating medical textiles through patient excretions. Studies have shown that this bacterium may still remain in improperly disinfected clean textiles, with a higher detection rate in infectious textiles.

• Staphylococcus aureus

Including drug-resistant strains (such as MRSA), this bacterium is transmitted through skin contact and survives well in warm, humid environments. If the washing temperature is insufficient, this bacterium may remain on the surface of the fabric.

• Pseudomonas aeruginosa

This bacterium is common in moist environments, such as washing equipment with accumulated scale, and easily causes nosocomial infections, especially for burn patients or those with weakened immune systems.

• Enterococcus and Klebsiella

These multi-drug resistant bacteria often remain on the surface of equipment due to irregular washing procedures or incomplete disinfection.

(2) Fungi

• Candida albicans

This fungus easily reproduces in humid environments and can spread to patients' skin or mucous membranes through contaminated textiles, causing infections.

• Zygomycetes (such as Mucor)

A hospital in Hong Kong once experienced an outbreak of Mucor infection due to fabric contamination, resulting in patient deaths. These fungi are highly resistant to conventional disinfectants and require high temperatures or special chemical disinfection for inactivation.

(3) Viruses and Other Pathogens

• Hepatitis B virus (HBV) and Human Immunodeficiency Virus (HIV)

Although these viruses survive for a shorter time in dry environments, if textiles are contaminated with blood or body fluids and not disinfected promptly, they may still be transmitted through needle punctures or other routes.

• Enteroviruses (such as Norovirus)

This virus can contaminate textiles through vomit or feces. If strict compartmentalization is not maintained during washing, cross-infection may occur.

II. Analysis of Contamination Level and Causes

(1) Contamination Rate Data

Studies show that the average microbial contamination exceedance rate of surfaces in hospital laundries is as high as 98.14%, the contamination rate of staff hands is 94.12%, and the exceedance rate of airborne colonies is 48%. In addition, French research found that 58% of "clean" bed sheets were already contaminated before contact with patients.

(2) Contamination Pathways and Risk Factors

• Defects in Washing Equipment

The spiral unloading channels of tunnel washers, due to insufficient temperature and scale accumulation, become breeding grounds for bacteria.

• Process Management Loopholes

Lack of strict compartmentalization (no complete isolation barriers between contaminated and clean areas, especially without internal isolation), mixed washing between hospitals, and un-disinfected transportation tools can all lead to cross-contamination.

III. Relationship to WS/T508 Standard

According to the standard WS/T 508-2016, the microbial indicators for clean textiles require: total bacteria count ≤200 CFU/100 cm², and no detection of pathogenic bacteria such as E. coli and S. aureus. However, due to equipment or operational problems in actual testing, some medical institutions find it difficult to meet the standards. To reduce risks, the following measures need to be taken:

• High-temperature disinfection (all surfaces in contact with textiles);

• Strict compartmentalization (internal is more important than external);

• Regular cleaning of scale, regular monitoring.

IV. Suggestions

From the above analysis, it can be seen that the types of bacteria detected in the medical laundry environment are highly coincident with common pathogens of hospital infections, and their contamination is closely related to equipment design, operational procedures, and disinfection effectiveness. Currently, the spiral unloading channels of tunnel washers have a high risk of pathogenic bacterial contamination due to problems such as insufficient temperature and scale accumulation. However, the WS/T508 standard has not yet adopted mandatory disinfection measures for these problems, resulting in some medical laundry institutions finding it difficult to meet the standard requirements in practice.

To protect patient health, it is recommended that relevant departments improve the WS/T508 standard, clarifying the disinfection requirements for tunnel washers to achieve the standard microbial indicators, and treating the supplies of medical staff and patients equally (such as including medical staff's supplies in the mandatory use range of tunnel washers, which will rapidly promote the upgrade and improvement of tunnel washers), by improving the standard, cutting off the cross-infection pathways from the source, and reducing the infection rate caused by medical textiles.