Riddle me this: Biofilms

In Drs. Gordon, Ordonez, and Jain’s article “Rifampin for biofilm-related infections,” the authors discussed the efficacy of specific therapies for biofilm-related infections. What about the role of biofilms in Staphylococcus aureus infections themselves? What enables them to challenge the immune system and facilitate antibiotic resistance?

Welcome to the matrix

Accept this month’s 5-item quiz challenge and see how well you know the wiles of this cunning pathogen that deploys a matrix “force field” to evade detection and eradication. What children are especially at risk? What treatment course gives the best outcomes?

1. A major difficulty in curing chronic persistent infections caused by Staphylococcus aureus (S aureus) is due to which of the following?

a) Lack of data on what causes chronic infection 

b) Development of biofilms

c) Inadequate duration of antibiotic use

d) All of the above

Answer: B (Development of biofilms)

Biofilms are aggregated communities of bacteria encased in a matrix that, during growth, may evade host defenses and become tolerant to antimicrobials. As such, eradicating biofilm-associated infections can be difficult. S aureus is a pathogen with the ability to develop and form robust biofilms and once developed these biofilms facilitate the antibiotic resistance (eg, methicillin-resistant S aureus [MRSA]) and phenotypic adaptability characterizing chronic persistent S aureus infections. Multiple infections associated with S aureus biofilms include those associated with implants and chronic wounds, as well as osteomyelitis, cystic fibrosis lung infection, and endocarditis.

Source

Bhattacharya M, Wozniak DJ, Stoodley P, et al. Prevention and Treatment of Staphylococcus aureus biofilms. Expert Rev Anti Infect Ther 2015;13(12):1499-1516.

2. S aureus is the most common pathogen in which of the following pediatric infections?

a) Skin and soft tissue infections

b) Septic arthritis

c) Osteomyelitis

d) Health care-associated infections

e) E and H only

f) All of the above

Answer: F (All of the above)

In children, S aureus is the most common pathogen causing both skin and soft tissue infections as well as some invasive infections such as septic arthritis and osteomyelitis. It also is the most common pathogen found in healthcare associated infections in children, both in infections acquired in the hospital or community.

Source

Kaplan SL. Staphylococcus aureus Infections in Children: The Implications of Changing Trends. Pediatrics 2016;137:1.

3. Persistent lung infections in children with cystic fibrosis caused by S aureus biofilms are associated with an increased risk of death.

True

False

Answer: True

Lung infections in people with cystic fibrosis are associated with biofilms and the persistence of long-term bacteria in the host. In children aged <17, the prevalent cause of these infections is colonization of the biofilms with persistent methicillin-resistant S aureus (MRSA) that is linked to worsening lung function. Data show that children with cystic fibrosis with chronic biofilm-associated infections (ie, MRSA infections of > 2 years) are at increased risk of death.

Source

Bhattacharya M, Wozniak DJ, Stoodley P, et al. Prevention and Treatment of Staphylococcus aureus biofilms. Expert Rev Anti Infect Ther 2015;13(12):1499-1516.

4. Which of the following is true regarding susceptibility of S aureus in US children?

a) Proportion of S aureus infections secondary to MRSA is decreasing

b) Clindamycin as empirical first-line treatment for S aureus infections continues to show a consistently high susceptibility to methicillin-sensitive S aureus (MSSA)

c) Susceptibility to oxacillin continues to increase

d) None of the above

e) Only A and C

Answer: E (Only A and C)

As seen in adults, the proportion of children infected with S aureus secondary to MRSA appears to be decreasing. A recent study found that MRSA-labelled isolates in a large pediatric population (41,745 isolates from >39,000 children receiving care through the US Military Health System) steadily declined to 31.6% in 2014 from a peak high of 46.4% in 2007. The highest rates of MRSA were seen in children aged 1 to 5 years. The study also found an increase over 10 years in susceptibility of isolates to oxacillin; in 2014, >60% of isolates were susceptible to oxacillin.

However, the study found a steady decline in clindamycin susceptibility, with a significant decline over 1o years in MRSA susceptibility (90% to 83%, P<0.0001). Stated differently, resistance to clindamycin increased to 14% in 2014 from 9.3% in 2005.

Source

Kaplan SL. Staphylococcus aureus Infections in Children: The Implications of Changing Trends. Pediatrics 2016;137(4):e20160101.

Sutter DE, Milburn E, Chukwuma U, et al. Changing Susceptibility of Staphylococcus aureus in a US Pediatric Population. Pediatrics 2016;137(3);e20153099.

5. The single most effective treatment for children with infections caused by S aureus biofilms is high potent antibiotics and bed rest.

True

False

Answer: False

No single effective treatment is available to treat children with infections caused by S aureus biofilms.  Although treating infections as early as possible is considered to result in the best outcomes, detecting biofilms early is often not possible as biofilms can persist for months to years before detection. Current treatment relies on physically removing source of infections (eg, implants, nonabsorbable sutures and necrotic tissue) along with antibiotic treatment, but these treatments often cannot eradicate the infection.

Source

Bhattacharya M, Wozniak DJ, Stoodley P, et al. Prevention and Treatment of Staphylococcus aureus biofilms. Expert Rev Anti Infect Ther 2015;13(12):1499-1516.