Detection of Polyclonality among Clinical Isolates from Prosthetic Joint Infections

Abstract

Prosthetic joint infection (PJI) is an increasingly important health concern in the Western world due to the rising number of joint arthroplasties. Although most infections are considered to be monomicrobial, the introduction of sonication procedures has led to an increase in the detection of polymicrobial infections. To date, no published studies have investigated the presence of different clones of the same species in the infected patient. The objective of this study was to analyze whether the phenomenon of polyclonality, or the appearance of different clones in the same sample, occurs in PJI. Bacteria isolated by sonication of the retrieved implant from patients with theoretically monomicrobial PJI were included in the study. Two techniques (random amplified polymorphic DNA [RAPD] and matrix-assisted laser desorption ionization-time of flight [MALDI-TOF] mass spectrometry) were used to determine the presence of several clones in the same sample. Results were analyzed to determine bacterial species and infection type (acute versus chronic). RAPD showed a predominance of polyclonal cases (16 of 19). However, when performing the analysis with MALDI-TOF, all cases were shown to be polyclonal. We were unable to establish any relationship between the two methodologies. Polyclonality is a common phenomenon in acute and chronic PJI. Further studies are needed to establish the potential implications of this phenomenon on patient outcomes. P rosthetic joint replacement, or arthroplasty, is a surgical procedure that has improved the quality of life for many people around the world, providing pain relief and improved functionality to limbs (1-3). However, 10% of all patients who undergo this operation develop complications at some point in their lives; although it is not the most common, infection is one of the most significant of these complications, having an incidence of 1% to 3% (1, 3, 4). The microorganisms that cause most cases of prosthetic joint infection (PJI) are those belonging to the genus Staphylococcus (60% of cases), of which infections caused by Staphylococcus aureus constitute 25%. Gram-negative organisms (Enterobacteriaceae, Pseudomonas aeruginosa, and other species) represent a smaller proportion of cases (10%) (1, 2, 5). Notably, up to 20% to 25% of PJIs are polymicrobial infections (1-3).When the growth conditions of the bacteria causing PJI become hostile, as may occur during antibiotic therapy, a coping mechanism known as spontaneous random hypermutation occurs as the bacteria attempt to overcome the unfavorable environment (6). This results in the development of polyclonality or the appearance of different clones in the same sample or environment (6). Polyclonality can also occur when the patient is infected with different clones from the same section of skin, which may occur either during surgery or afterwards and is likely a more common phenomenon (7). Several reports have found polyclonality in monomicrobial infections among isolates of small-colony variant staphylococci, which present phenotyp...

Characterization of microbial mixtures by mass spectrometry

“…After removal of blood cells via differential centrifugation or lysis, samples are either deposited directly on to the MALDI target plate or bacteria are lyzed and proteins are extracted using a common ethanol/formic acid approach. With some exceptions, labs using Biotyper typically perform bacterial cell lysis and protein extraction (eg,), but groups using the Vitek system commonly report deposition of the sample directly onto the MALDI target (eg,). While both approaches have been used with polymicrobial cultures, no direct comparison has been conducted between the two with regard to polymicrobial performance.…”

The Epidome - a species-specific approach to assess the population structure and heterogeneity of Staphylococcus epidermidis colonization and infection

“…A large percentage of hospital S. epidermidis isolates are methicillin-resistant (MRSE), and especially multidrugresistant S. epidermidis (MDRSE) lineages, such as sequence type (ST)2, ST5, ST23, and ST215, are spreading both locally and globally in hospital environments [6,8,[13][14][15][16][17]. Identification of S. epidermidis as an invasive infectious pathogen is not trivial and distinguishing contamination from true infection can be challenging, and research suggests that high subspecies heterogeneity is common in healthy carriage [18,19], but also in patients suffering from PJIs and atopic dermatitis [20,21]. This observation is in contrast to the nature of Staphylococcus aureus communities that are known to be highly clonal [22][23][24].…”

The Epidome - A species-specific Approach to Assess the Population Structure and Heterogeneity of Staphylococcus Epidermidis Colonization and Infection

“…A large percentage of hospital S. epidermidis isolates are methicillin-resistant (MRSE), and especially multidrug-resistant S. epidermidis (MDRSE) lineages, such as sequence type (ST)2, ST5, ST23, and ST215, are spreading both locally and globally in hospital environments [6,8,[13][14][15][16][17]. Identi cation of S. epidermidis as an invasive infectious pathogen is not trivial and distinguishing contamination from true infection can be challenging, and research suggests that high sub-species heterogeneity is common in healthy carriage [18,19], but also in patients suffering from PJIs and atopic dermatitis [20,21]. This observation is in contrast to the nature of Staphylococcus aureus communities that are known to be highly clonal [22][23][24].…”