Sunday, July 23, 2017

Propionibacterium - be aware, drug resistance is coming!

Antimicrobial susceptibility and phylogenetic analysis of Propionibacterium acnes isolated from acne patients in Japan between 2013 and 2015

These authors note that the prevalence of antimicrobial-resistant Propionibacterium acnes strains isolated from acne patients has been increasing. They tested antimicrobial susceptibility among P. acnes from acne patients visiting a specialized dermatology clinic between 2013 and 2015. 

Rates of resistance to macrolides (e.g. Azithromycin, Erythromycin) and clindamycin were 44.3 (31/70) and 38.6% (27/70), respectively. 

The erm(X) gene, which confers high-level clindamycin resistance was detected in six isolates (single-locus sequence type clades A, E, F, H and K), 

No resistance determinants were identified in eight strains (clade F) showing high-level resistance to clindamycin. Strains of clade F, which were very rarely isolated from healthy individuals, were more frequently recovered from patients with severe acne (40.0%) than those with mild acne (23.3%).

P. acnes isolates from patients previously treated with macrolides and clindamycin showed a macrolide resistance rate (55.3%) significantly higher than that of those from patients not having received these treatments (21.7%, P < 0.05). 

They concluded that there was an increase in macrolide-resistant P. acnes prevalence  due to the use of antimicrobial agents for acne treatment. 

The Propionibacterium in this study were sensitive to Amoxicillin and tetracyclines.

Comment: While (as shown by the chart below) patients with acne are much younger than those at risk for shoulder periprosthetic infections, 

we know that bacteria are shared among individuals by direct and indirect contact (see below)
Microbiota bacteriana asociada al papel moneda de circulación en Colombia

Commonly used objects such as currency paper can be colonised by bacteria and can serve as carriers of microbes. This colonisation might expose us to unnoticed pathogenic bacteria. In this study, the researchers obtained a detailed panorama of the microbes that can be carried on currency notes in Colombia by using 454 next-generation deep sequencing of 16S amplicón libraries. A total of 233 bacterial genera were detected and classified, 12 of which are potential human pathogens. The most abundant genera were Propionibacterium, Streptococcus, Staphylococcus and Pseudomonas. To date, this is the first in-depth analysis of the microbiota carried by circulating banknotes in our continent and it offers insights into daily exposure to microbes when using banknotes in Colombia.

The same must hold true for the currencies of all countries.

For the historical reference to 'follow the money' see this link.

Comment: This important study complements other evidence that Propionibacterium, including drug resistant strains, can be easily passed from one person to another. See: Propionibacterium acnes and bacterial resistance

In this review article, the authors point out that Propionibacterium acnes is one of the main microorganisms found on the skin. It is predominantly found in hair follicles, prefers anaerobic conditions, preferably colonizes the areas with high sebum production, and is the main bacterium involved in the pathogenesis of acne. They suggest that the indiscriminate use of antibiotics for the treatment of acne vulgaris can result in the development of bacterial resistance.

Several observations in this article are of interest to us shoulder surgeons:

There are over one million Propionibacterium per square centimeter of skin.

Propionibacterium inhibits the invasion of the skin by common pathogens such as Staphylococcus aureus and Streptococcus pyogenes.  Its hydrolyzation of triglycerides with the release of free fatty acids (including propionic acid) contributes to the acid pH of the skin’s surface, which is another factor for skin protection. Note: this suggests that elimination of Propionibacterium from the skin of the surgical site may open the door for worse bugs.

There are many different types of Propionibacterium; on average, each individual has 3 different Propi ribotypes on the skin each with different pathogen potential and different resistance patterns. 

Persons can transmit the different clones to other individuals, and thus resistant bacteria can be spread throughout the population by 'rubbing elbows'.

There has been an increasing number of cases of antibiotic- resistance by P. acnes over the years: in the UK, the resistance rate increased from 34.5% in 1991 to 55.5% in 2000;156 94% of  the isolates in Spain and 51% from the isolates in Hungary were  resistant to at least one antibiotic. The highest resistance rates are related to erythromycin, with cross-resistance to clindamycin. 

Resistance comes from gene mutation:

In cases of severe infections caused by P. acnes, surgical procedures should be combined with crystalline penicillin, vancomycin, daptomycin, and rifampicin due to their effect on the biofilm.

The reasons for the emergence of Propionibacterium as a problem in shoulder surgery is becoming clearer - the use of antibiotics for acne and for other reasons is changing the genetics of the bacterium to favor antibiotic resistance and the resistant strains are being exchanged within the human population.

The reader may also be interested in these posts:

Information about shoulder exercises can be found at this link.

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