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Mold Blindspots Series

Part 4: Hospital Acquired Infections

October 12, 2023

Nosocomial Infections from Hospitals and Medical Facilities

By Cesar Collado

Nosocomial infections are infections that patients acquire while admitted to a healthcare facility.  These hospital infections generally develop 48 hours or later after admission.  While hospitals are regularly cleaned and disinfected, some practices and products may still allow microbial growth. Life-threatening antibiotic resistant infections can lead to very serious problems like sepsis or even death. Nosocomial infections are most often from staphylococcus aureus, e-coli, or enterococci if bacterial.  Additionally, Candidiasis is a commonly occurring fungal infection.

Microorganisms can survive a wide range of temperatures, especially fungi. However, room temperature is consistently conducive to mold growth. A microbe that falls into an environment where it cannot survive will eventually die, but many cases have been recorded of viable mold spores existing for thousands of years dormant, then growing once water is present.

Nosocomial or Hospital Infection Causes

The main causes of these infections occur as a result of medical devices used to deliver treatment.  Surgical procedures, urinary catheters, central venous catheters, and mechanical ventilation are often the sites where the infection begins. The overuse or inappropriate use of antibiotics also contribute to the nosocomial infection epidemic.

Microbial Sources for Nosocomial or Hospital Infections

People Are At The Root of Nosocomial or Hospital Infections

People are the greatest source of microbial contamination. Nosocomial infection risk is almost entirely related to human activity. Microbes live all over the human body on our skin, hair, clothing, and in moisture droplets from our breath. Anything humans touch, shed (think flakes of skin or hair), breath on, cough on, or brush up against, is a source of microbial contamination. Movements as simple as walking can emit more than 10,000 particles per minute. However, protective gear like gloves, gowns, masks, and booties help contain microbial contamination. As a result, the more human interaction during a hospital visit can be limited, the lower the risk of microbial contamination.

Moisture Issues Can Lead to Hospital Infections

Water or moisture is the other main source of microbial contamination. Microorganisms readily exist and multiply in water. Thus, using sterile water during product processing flushes and equipment cleaning is critical to prevent unwanted microbial contamination. However, nosocomial infections still occur with rigorous cleaning and disinfection.  Water control is crucial to sanitation success. Microorganisms that are native to fresh water and ubiquitously found there include Pseudomonas, Bacillus, Escherichia coli, Bacillus sp. and are commonly washed into the water during rainfall. Escherichia coli comes from sewage contaminants in the water supply.

Manufactured Materials

The materials used for building and furnishing material contamination often comes from plants, animals, or manufactured sources. Thus, some raw materials can be contaminated with pathogens such as e-coli and Salmonella. Even synthetic raw materials (in contact with humans during production) are subject to contamination if they are not produced under aseptic conditions. Given that molds are ubiquitous, they are also an issue. This is especially problematic for raw materials that have undergone long-term storage in humid, wet, or outside environments. Multiple coexisting microorganisms are common in all of these settings.

Cleaning Products Can Lead to Drug Resistant Hospital Infections

There is some antiquated beliefs and misinformation on the use of bleach to disinfect.  Bleach does not penetrate porous surfaces.  As a result, the use of bleach can actually lead to accelerated mold growth from hyphae (roots) that remain after cleaning with bleach.  Read more about bleach HERE.  Read about the chemistry of cleaning mold HERE.

Medical Product Packaging

Packaging materials, such as rubber closures, paper, and even glass, can facilitate microbial growth. Most plastic materials have relatively low-surface microbial contamination. However, any rubber closures or paper (such as cardboard containers) are excellent homes for mold growth. Even glass can support mold spore growth (such as Penicillin and Aspergillus) or the growth of some bacteria (such as Bacillus). Thus, appropriate packaging and storage conditions are essential to prevent microbial contamination of all products entering a healthcare setting.

Building Materials

There is a strong connection between building materials and microbial contamination. Mold growth commonly occurs on walls and ceilings, particularly in the presence of moisture.   The development of disinfectant-resistant biofilms is a result of continued disinfection using chemicals. Walls and ceilings can contain molds, such as Cladosporium sp and Aspergillus sp. The drywall or other non-mold-inhibiting materials that paint covers is a source of nutrients for these mycotoxin producing molds. Contamination is a risk for any walls, ceilings, or floors if exposed to water or moisture. Disinfectant-resistant biofilms can quickly develop in these areas of the building if moisture is present.

Self-Contained Equipment Can Be the Cause of Nosocomial Infections

Complex equipment is notoriously difficult to clean. Equipment is often self-contained, and any crevices can harbor microbial contamination. In hospitals, there are numerous challenges to clean and disinfect equipment.  Cleaning of equipment can sometimes be the source of contamination. Hard-to-clean equipment locations are harbors for microbial contamination. Such locations are often small and patterned. Some examples of difficult-to-clean areas are screw threads, agitator blades, valves, and pipe joints. Note that cleaning equipment (sponges, brooms, and mops) can become sources of contamination if not sterilized or replaced regularly.


Microorganisms can survive in the air for relatively brief periods until they land on surfaces that can support their survival and growth. Thus, microorganisms use air as a vehicle for transportation more than an environment for growth.

Dry Environment

Organisms that can also thrive in a dry environment include Bacillus, Clostridium, Staphylococcus, Streptococcus, Penicillin, Aspergillus, and Rhodotorula. The degree of airborne contaminants in an environment depends on the relative levels of dust, particulates, and humidity. The higher the dust, particulate, or humidity levels, the greater the risk of viable airborne contaminants and nosocomial infections. Air sampling can be utilized as an effective means to monitor airborne contaminants.

MRSA and Antimicrobial Resistance

MRSA, which stands for Methicillin-Resistant Staphylococcus Aureus, is commonly found in hospitals because it has developed resistance to several antibiotics, including methicillin. Many nosocomial infections are MRSA.  Hospitals house people with weakened immune systems or open wounds who are more susceptible to infections, making them more vulnerable to MRSA. Furthermore, the close proximity of patients and the extensive use of antibiotics in healthcare settings contribute to the spread and persistence of MRSA. Strict infection control measures are essential in hospitals to prevent its transmission.


It is important to understand the complexities of microbial contamination in seemingly “sterile” environments like hospitals, as nosocomial infections can be deadly.  We can gain a deeper understanding of the sources, risks, and implications of microorganisms in our healthcare settings. Recognizing the crucial role of infection control measures, protective gear, sterile processing, and continuous monitoring in mitigating microbial risks will help ensure our safety within healthcare settings.

Mold Blind Spots Series

This article series sheds light on often overlooked mold sensitivity triggers or mold blind spots. Look for our weekly published articles beginning mid-September 2023.

Mold Blind Spot 1:

The Superantigen Response to Mold

There are certain situations where mold induces a cytokine storm.  A cytokine storm is an intense inflammatory reaction that can lead to life-threatening conditions. The immune system goes into overdrive in producing inflammatory signals called cytokines.  This condition is difficult to diagnose and is often misdiagnosed in emergency settings.

Mold test Plates
Mold Blind Spot 2:

Microbial Coexistence

Most infectious conditions involve multiple microbial contaminations.  Single organism infections do occur in various environments. However, single fungal microorganism contamination is a rare phenomenon unless the specific mold has colonized and reproduced significantly in part of the human body.

Microbial soup
Mold Blind Spot 3:

What is Microbial Soup?

October 5, 2023

In most infection cases, biofilms are formed collaboratively by different microorganisms in order to mutually survive in the body. There are many common microbial combinations that are prevalent in water-damaged homes.

Hospital infections
Mold Blind Spot 4:

Hospital Acquired Infections

October 12, 2023

While hospitals would seem to be well maintained and regularly disinfected, many people develop infections after being in the hospital for a couple days.  The “nosocomial” infections are prevalent, often resistant, and can be life threatening.

Mold Blind Spot 5:

Vulnerable Populations

November 2, 2023

The presence of mold can pose significant health risks for immunocompromised individuals. Explore the unique health circumstances that impact a family’s well-being.

Mold test Plates
Mold Blind Spot 6:

Aspergillosis, A Common Fungal Infection

November 9, 2023

Aspergillus is the most common fungal infection that often involves hospitalizations. Aspergillosis infections involve significant reproduction and colonization inside the human body. Aspergillus is also a mycotoxin producing mold. It is helpful to understand fungal infections and the impact on health and potential treatment approaches.

Mold Blind Spot 7:

Candida Overgrowth

November 16, 2023

Candida albicans are single cell yeasts that are part of the fungi empire and also a component of the human microbiome. Candida overgrowth, often linked to diet and antibiotic usage, can have significant chronic and acute health implications.

Mold test Plates
Mold Blind Spot 8:

Understanding "The Body’s Toxic Load"

November 22, 2023

The human body is limited in it’s ability to process toxic substances like pollutants, heavy metals, and more. Learn how mold illness can result from single severe exposure, or cumulative minor ones, leading to severe mold sensitivity. The body’s “toxic load” is referenced when the body has reached its lifetime maximum of toxins and becomes hypersensitive to almost any allergen or toxin.