Take a Trip to the Lungs with 12 Bacterial Species (Part III: Oral Hygiene)

By: Karen Sheffler

August 11, 2014

Oral Hygiene & Aspiration Pneumonia: Part III

Escherichia Coli Bacteria. Rod-shaped anaerobic bacteria commonly found in the lower intestines. However, pathogenic strains take the fecal->oral route of transmission to cause disease.

Part III of Oral Hygiene and Aspiration Pneumonia Prevention.

By Karen Sheffler, MS, CCC-SLP, BCS-S

As we are coming and going from our summer vacations, consider the travels that bacteria may take around the body.

The germs in the mouth are the same germs that travel to the lungs to cause pneumonia, according to Shay (2014). These bacteria can be found in the hospital or nursing facility environment, on the staff and visitors, and on or in the patients themselves.

See also Part I and Part II of Oral Hygiene and Aspiration Pneumonia Prevention, and Part IV on HOW to perform effective oral care..

Shay shared a chart from Sarin, et al (2008). These researchers isolated 12 periodontitis microflora that were the same as the nosocomial pneumonia microflora.

Here are the 12 mouth to lung microflora:

  • Staphylococcus aureus
  • Fusobacterium nucleatum
  • Haemophilus influenzae
  • Actinomyces species
  • Peptostreptococcus
  • Pseudomonas aeruginosa (gram-negative)
  • Lactobacillus species
  • Klebsiella pneumoniae (gram-negative)
  • Enterobacter cloacae
  • Facultative anaerobes
  • Escherichia Coli (gram-negative that can be transmitted through a fecal to oral route)
  • Acinetobacter spp. (e.g., Acinetobacter baumanii is a gram-negative rod)

Fourrier et al (1998) studied dental plaque in ICU patients and found similar microflora. Staphylococcus aureus (methicillin-resistant) colonized by day 5. By day 5 and day 10, they isolated gram-negative bacilli that were more resistant to antibiotics: Klebsiella aerogenes, A. baumanii, and P. aeruginosa gram-negative bacilli. Out of the 57 patients studied, 15 patients developed a nosocomial infection (hospital-acquired infection) in the ICU. Out of these 15, 8 patients had bacteria isolated in the blood or from bronchoalveolar lavage (BAL) that were also isolated in their dental plaque.

Another picture of E Coli Bacteria

Oral hygiene helps reduce bacterial and fungal overgrowth:

In addition to the bacteria listed above, Kuyama et al’s review (2010) discussed Candida albicans and its adherence to dentures in the elderly. The acrylic resin of the dentures is easily colonized by Candida species, as well as oral-endogenous bacteria (from within the patient’s own system). This promotes further colonization by exogenous species (coming from outside of the patient’s system), such as: Staphylococcus species, Pseudomonadaceae, and members of Enterobacteriaceae. These can lead to aspiration pneumonia.

Good oral care reduced:

  • Candida species significantly (Abe, et al, 2006, Abe, et al, 2001).
  • Salivary bacterial counts (Abe, et al, 2006).
  • Cell numbers of potential respiratory pathogens (Abe, et al, 2001).
  • Pneumonia and febrile days in dentate patients (Abe, et al, 2006).
  • Pneumonia, febrile days, and death from pneumonia in both dentate and edentulous patients (Yoneyama, et al, 2002).

Even edentulous patients are at risk

It was once believed that edentulous patients had a lower risk for aspiration pneumonia. Even the Fourrier, et al study (1998) specifically excluded patients who were completely toothless and did not wear any dental appliance.

Abe, et al (2008) studied 71 elderly edentulous patients. They created a Tongue Plaque Index, which was described as “tongue-coating not present” vs “tongue-coating significantly present.” Patients with tongue-coating had higher salivary bacteria content and a higher relative risk of developing aspiration pneumonia. This suggests, we can use tongue-coating as a pneumonia risk factor in elderly without teeth or dentures.

Types of pneumonia

Shay (2014) discussed how Community Acquired Pneumonia typically is due to Hemophilus influenza and Staphylococcus pneumoniae; however, Hospital Acquired Pneumonia is due to Staphylococcus aureus and gram-negative bacilli.

Hospital Acquired Pneumonia has a greater mortality than community acquired, and it is the leading cause of death in nursing facilities.

These same microorganisms cause Ventilator Acquired Pneumonia (VAP), which is the leading cause of complication from mechanical ventilation and the leading cause of death in the ICU. Clear research has linked VAP to oral cleanliness, per Shay.

HOW and WHY do these microorganisms grow and get into the lungs? 

As far back as 1978, Schwartz et al found that ALL their subjects had gram-negative organisms colonizing the trachea after only 3 days of endotracheal intubation.

Munro & Grap (2004) discussed the following risk factors:

  1. Growth of pathogenic bacteria is due to presence of dental plaques, creating a thick biofilm. This is the origin of the infection. See also Part I and Part II of Oral Hygiene and Aspiration Pneumonia Prevention.
  2. Endotracheal (ET) tubes carry pathogens from the oropharynx to the lower respiratory tract,
  3. ET tubes stimulate excessive mucus secretions, and
  4. ET tubes interfere with the cough reflex and the ability to expel secretions and foreign material.

Additional factors promoting bacterial colonization of respiratory system, even in the absence of intubation: (Shay, 2014; Munro & Grap, 2004)

  1. Open mouth posture, contributing to dry mouth, poor hygiene, and easy access for bacteria
  2. Lack appropriate oral care (i.e., debridement with a toothbrush)
  3. NPO status, further altering the natural debriding mechanisms of chewing, salivary flow and swallowing
  4. Medications causing xerostomia
  5. Fluid imbalances/dehydration increasing xerostomia
  6. Stress and anxiety causing immunocompromise. Bacteria that cause pneumonia have been found in oral flora of immunocompromised patients.
  7. Autoimmune attack on the salivary glands due to illness and/or due to a specific disorder (i.e., Sjogren Syndrome)
  8. Institutional environment with a biodiversity of microorganisms
  9. Bedridden status
  10. Dependency

These factors are similar to Susan Langmore, et al’s (1998, 2002) predictors of aspiration pneumonia. Dependency on others for feeding and cleaning the mouth were top risk factors. Also included were: number of decayed dentition, number of medications, and bedridden status in a medically complex patient (causing a decreased immune response). Additionally, if there is a smoking history, the lungs will have poor pulmonary clearance if the bacteria travels there.


Bacteria from the mouth causes pneumonia.

There has been ample research to warrant hospitals to create oral hygiene policies and procedures. Acute care facilities need to expand good oral hygiene programs beyond just the intubated patients in the ICU. There is an acceptance now of providing excellent oral care to the ventilator patient in order to prevent VAP, but these same oral care procedures have to be implemented across all aspects of acute and subacute care. Patients with teeth and without teeth will benefit. The teeth and gums need to be brushed with a soft toothbrush, and the mouth needs to be rinsed. Scrubbing the tongue and palate and removing debris is equally critical. Recall, from Part I of Oral Hygiene and Aspiration Pneumonia, that the green swabs that are in the hospitals to “clean” the mouth are “wimpy” and do NOT remove plaque, per Dr Shay (2014, April).

What is next in Part IV

The next blog on this topic will include HOW to prevent nosocomial (hospital-acquired) aspiration pneumonia. This will address: oral care procedures and mouthwashes. We need to start thinking about “oral care” as “oral infection control” and “oral decontamination for aspiration pneumonia prevention.” In Part IV, I will also discuss oral care and oral comfort in patients with head and neck cancer who may have mucositis and thrush.

Further reading on this topic:

Check out ASHAwire for John R. Ashford’s reviews:

  • Oral Care Across the Ages (2012): in SIG 13 Perspectives on Swallowing and Swallowing Disorders (Dysphagia), 2012, Vol. 21: 3-8.
  • Oral Care and the Elderly (2008): in SIG 13 Perspectives on Swallowing and Swallowing Disorders (Dysphagia), 2008, Vol. 17: 19-26.


Abe, S., Ishihara, K., Adachi, M. & Okuda, K. (2008). Tongue-coating as risk indicator for aspiration pneumonia in edentate elderly. Archives of Gerontology and Geriatrics, 47 (2), 267-275.

Abe, S., Ishihara, K., Adachi, M. & Okuda, K. (2006). Oral hygiene evaluation for effective oral care in preventing pneumonia in dentate elderly. Archives of Gerontology and Geriatrics, 43 (1), 53-64.

Abe, S., Ishihara, K. & Okuda, K. (2001). Prevalence of potential respiratory pathogens in the mouths of elderly patients and effects of professional oral care. Archives of Gerontology and Geriatrics, 32 (1), 45-55.

Fourrier, F., Duvivier, B., Boutigny, H. Roussel-Delvallez, M & Chopin, C. (1998). Colonization of dental plaque: A source of nosocomial infections in the intensive care unit patients. Critical Care Medicine, 26 (2), 301-308.

Kuyama, K., Sun, Y. & Yamamoto, H. (2010). Aspiration pneumonia: With special reference to pathological and epidemiological aspects, a review of the literature. Japanese Dental Science Review, 46, 102-111.

Langmore, S., Terpenning, M., Schork, A., Chen, Y., Murray, J. et al. (1998). Predictors of aspiration pneumonia: How important is dysphagia? Dysphagia, 13, 69-81.

Langmore SE, Skarupski KA, Park PS & Fries BE. (2002). Predictors of aspiration pneumonia in nursing home residents. Dysphagia17, 298-307.

Munro, C.L. & Grap, M. (2004). Oral health and care in the intensive care unit: State of the science. American Journal of Critical Care, 13, 25-34.

Sarin, J., Balasubramaniam, R., Corcoran, A.M., Laudenbach, J.M. & Stoopler, E.T. (2008). Reducing the risk of aspiration pneumonia among elderly patients in long-term care facilities through oral health interventions. Journal of American Medical Directors Association, 9, 128-135.

Shay, K. (2014, April). Dental perspectives on aspiration pneumonia causes and management. Health Care and Business Institute. Lecture conducted at ASHA conference, Las Vegas, NV.

Schwartz, S.N., Dowling, J.N., Benkovic, C., Dequittner-Buchanan, M. Prostko, T. & Yee, R.B. (1978). Sources of gram-negative bacilli colonizing the tracheae of intubated patients. Journal of Infectious Diseases, 138, 227-231.

Yoneyama, T., Yoshida M, Ohrui T, Mukaiyama H, Okamoto H, Hoshiba K,et al. (2002). Oral care reduces pneumonia in older patients in nursing homes. JAGS, 50, 430-433.