What are the key principles of preventing higher bacteria – actinomycoses and ?


Actinomycoses is an uncommon, indolent, slowly progressive bacterial infection caused primarily by actinomycoses. Normal and immunocompromised hosts can become infected.

Three presentations should prompt consideration of actinomycoses:

  • Chronicity with progression across tissue borders and mass-like features mimicking malignancy, with which it is often confused.

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  • Sinus tract development.

  • Refractory or relapsing infection after a short course of antimicrobials.

Virtually every organ or body site can become infected:

  • Head and neck and the thoracic and abdominal-pelvic regions being most common.

  • CNS, musculoskeletal and soft-tissue, and disseminated infection are less common.

  • In vivo growth usually results in the formation of characteristic macro- or microscopic “sulfur granules” composed of bacteria and host components.

Actinomycoses normally colonize the human mouth, colon and vagina. The key step leading to infection is disruption of mucosa. The following appear to facilitate the initiation and/or propagation of infection.

  • Trauma

  • Poor dental hygiene

  • Immunocompromised state

  • Radio- or chemotherapy

  • Bisphosphonate use

  • Ulcerative mucosal infection

  • Foreign bodies (especially intrauterine contraceptive devices (IUCD))

  • Actinomyces has been grown from a contaminated multidose vial, but resultant infection has not been demonstrated

  • A “pseudo-outbreak” of Actinomyces associated with bronchoscopy was due to changes in anaerobic culture requests and culture procedures.

Actinomyces is part of the human microbiome; therefore pathogen entry/exposure cannot be avoided.

  • The key step for minimizing the chances of developing infection is the avoidance of mucosal trauma.

  • However, avoidance of all causes of micro- and macroscopic mucosal trauma is impossible.

  • The only practical preventative measures are optimizing dental hygiene, especially with the use of bisphosphonates & removal of an IUCD when no longer necessary.

Since little can be done to prevent infection timely recognition, diagnosis and treatment becomes equally if not more critical.

  • This is particularly important since most cases of actinomycoses can be successfully treated with a prolonged course of antimicrobials.

  • Unfortunately, actinomycoses is a unique infection that possesses clinical features suggestive of malignancy.

  • Therefore a high level of clinical acumen is requisite to avoid unnecessary surgical interventions.


Nocardiosis is an uncommon, acute, subacute, or chronic infection caused by various species from the genus Nocardia. Infection is more common in an immunocompromised host but a normal host can also become infected.

  • Pulmonary infection is most common.

  • Dissemination can occur to virtually any organ, with a particular tropism for the CNS.

  • Primary cutaneous or subcutaneous infection can follow direct introduction after trauma or puncture wounds.

  • Serious and disseminated infection is more common in immunocompromised patients (especially with cell-mediated (e.g., transplants, HIV, steroid use) or neutrophil dysfunction (e.g., chronic granulomatis disease) but can occur in normal hosts.

  • A pseudoepidemic of nocardiosis has been described due to contamination of a BACTEC 460 blood culture machine

The source of nocardiae is the environment where they are ubiquitous, particularly in soil and decaying organic material.

  • Inhalation of airborne organisms is believed to be responsible for pulmonary disease and dissemination most commonly occurs in that site.

  • Nocardiae have been isolated from dust in patient’s rooms.

  • Primary infection of soft-tissue is due to direct inoculation with material containing nocardiae. Rarely a cat-scratch has been implicated as the instrument for inoculation.

  • Nocardiae have been cultured from human skin

  • Colonization of the human respiratory may occur in the absence of infection

There are no established measures to prevent infection. Logical measures include:

  • Immunocompromised patients should avoid decaying organic matter & excessive aerosolized dust such as construction sites.

  • Wards containing immunocompromised patients should avoid unnecessary generation of aerosols that might contain norcardiae such as construction sites, potted indoor plants, or open windows.

What are the conclusions of clinical trials and meta-analyses regarding control of higher bacteria – actinomycoses and ?

No clinical trials or meta-analyses have been performed that address the control of Actinomycoses and Nocardia.


  • Health care-associated (HA) acquisition of infection from a point source (e.g., food, water, medical instrument, contaminated infuscate), person-to-person, or from the inanimate environment has not been documented and has an extremely low biologic plausibility.

  • Therefore additional infection control procedures are not recommended and have not been studied.


  • Since patients have acquired disease during hospitalization, albeit uncommonly, HA acquisition of infection seems to have occurred.

  • The source of infection is unclear but most reports suggest the environment.

  • Definitive molecular documentation to establish the source of infection & in some cases that the infection is HA is generally lacking (see below).

  • HA acquisition generally is related to special circumstances (e.g., renovation, environment contamination) that do not lend themselves to modification by infection control practices under normal circumstances.

  • The incidence of HA acquisition is rare for an uncommon infection (see below).

  • HA transmission of infection via a point source or person-to-person spread is even rarer if it occurs at all (see below).

  • Therefore additional infection control procedures are not recommended and have not been studied.

What are the consequences of ignoring the control of higher bacteria – actinomycoses and ?




HA acquisition of nocardial infection seems to occur under special circumstances, which cannot be modified by infection control practices under normal circumstances. Therefore, control measures have not been recommended or studied and therefore cannot be ignored.

What other information supports the conclusions of studies on higher bacteria – actinomycoses and Nocardia, e.g., case-control studies and case series?


No information exists to support HA acquisition and this possibility has an extremely low biologic plausibility


Data that supports the HA acquisition of Nocardia is based on case reports and a single case control study. However documentation to identify the source of acquisition is often lacking (see below for details).

Summary of current controversies regarding higher bacteria – actinomycoses and Nocardia.




  • It would be an over-statement to say that an infection control controversy exists for Nocardia. Although HA acquisition seems to occur, with the source being most likely the inanimate environment, no infection control measures are recommended to prevent the acquisition of nocardiosis. This is likely due to the fact that acquisition occurs under special circumstances that have resulted in an occasional case cluster. Under those circumstances patient units have undergone formaldehyde fumigation to prevent additional transmission, but controlled studies on the efficacy of this approach have not been performed.

  • More controversy surrounds whether the source of HA transmission of Nocardia is mediated by person-to-person spread. Most authorities state this does not occur. Definitive evidence to support or refute this possibility does not exist. However, some evidence and biologic plausibility suggests this possibility since Nocardia is capable of colonizing human skin.

  • There is no evidence to support direct, aerosol-mediated person-to-person transmission

  • If person-to-person spread does occur it appears to be a rare occurrence.

  • To date, there has been no data to support a point source as a means of transmission and this possibility is less biologically plausible.

  • No infection control measures are recommended to prevent the transmission of nocardiosis; although an occasional case report suggests this should be considered.

  • Although unproven, it has been suggested that Nocardia may enter the hospital inanimate environment from infected wounds or soft-tissue. Likewise health care personnel, their clothes or instruments could be colonized in that setting. If so, contact precautions could decrease HA infection.

What is the impact of higher bacteria – actinomycoses and Nocardia and the need for control relative to infections at other sites or from other specific pathogens?

Although infections due to actinomycoses and Nocardia can result in significant morbidity and mortality, these infections are uncommon compared to most other pathogens.

  • For Actinomycoses there is no need for enhanced infection prevention precautions.

  • For Nocardia, it is unclear whether enhanced infection precautions would be needed or of any value under normal circumstances.

  • It is logical that wards containing immunocompromised patients (e.g., transplants) should be closed when construction or renovation generates dust, however, whether this would impact the incidence of nocardiosis has not been tested.

  • Likewise there is no data on whether contact precautions would impact the incidence of nocardiosis in the setting of infected wounds or soft-tissue disease.

  • Even if infection control practices could affect the incidence of nocardial infection the impact would be small, even in high-risk immunocompromised patients since the incidence of infection is low.

Overview of important clinical trials, meta-analyses, case control studies, case series, and case reports related to infection control and higher bacteria – actinomycoses and Nocardia.




There are no meta-analyses that address nocardiosis and infection control measures.

  • Case series, primarily of clusters of infection, cases reports, and a single case control study suggest that HA acquisition occurs, albeit rarely.

See Table I.

Table I.n

Published reports addressing possible HA acquisition of Nocardia


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