Rifampicin resistance and risk factors associated with significantly lower recovery rates after two stage revision in patients with prosthetic joint infection

PURPOSE

Rifampicin plays a key role in the management of prosthetic joint infections (PJIs), however, the emergence of rifampicin resistance is associated with less favorable clinical outcomes. The purpose of this study was to investigate the impact of rifampicin resistance and other patient-related factors on recovery rates among patients with PJI undergoing two-stage revision.

METHODS

We reviewed medical records and microbiology reports of 73 patients (41 males and 32 females) undergoing two-stage revision due to PJI between 2017 and 2019. Patient-specific data, co-morbidities and the antibiotic resistance of microbiological isolates were registered. 48 patients had hip, 22 had knee, 2 had shoulder and 1 had elbow joint infection. Obtained data were statistically analyzed with a logistic regression model.

RESULTS

Rifampicin-sensitive organism was isolated in 53 cases (72.6%). Recovery rate was 92.5% in the sensitive and 60.0% in the resistant group. We observed that rifampicin resistance significantly reduced the probability of recovery. Furthermore, in the rifampicin-sensitive group, the probability of recovery decreased with advancing age with a significant drop above the age of 60 years. The effect of age is negligible in the rifampicin-resistant group. We also found that type 2 diabetes mellitus has a negative effect on recovery. Coagulase-negative Staphylococci were predominant in the rifampicin-sensitive (50% of the isolates) and Gram-negative rods in the resistant group (40%).

CONCLUSIONS

Rifampicin resistance was associated with lower recovery rates among patients undergoing two-stage revision due to PJI. Higher age and type 2 diabetes mellitus had negative impact on clinical outcome.

In vitro antimicrobial susceptibility testing of human Brucella melitensis isolates from Ulanqab of Inner Mongolia, China

Background

Brucellosis is an endemic disease in the Inner Mongolia Autonomous Region of China and Ulanqab exhibits the highest prevalence of brucellosis in this region. Due to the complex nature of Brucellosis, a cure for this disease has proven to be elusive. Furthermore, the reduced susceptibility of Brucella spp. to antimicrobial agents has been reported as a potential cause of therapeutic failure. However, detailed in vitro antimicrobial susceptibility patterns pertaining to Brucella isolates from this region have not yet been published. The aim of this study was to evaluate the antibiotic susceptibility profile of Brucella melitensis clinical isolates from Ulanqab, Inner Mongolia, China.

Methods

A total of 85 B. melitesis isolates were obtained from humans in Ulanqab of Inner Mongolia, China; the antimicrobial susceptibility of 85 clinical isolates to nine antibiotics was assessed using the E-test method according to the CLSI (Clinical and Laboratory Standards Institute) guidelines.

Results

All of the tested isolates were susceptible to minocycline, sparfloxacin, doxycycline, tetracycline, ciprofloxacin, gentamicin and levofloxacin. Resistance to rifampin and cotrimoxazole was observed in 1.0% (1/85) and 7.0% (6/85) of the isolates, respectively. However, rpoB gene mutations were not observed in single isolates exhibiting resistance to rifampin.

Conclusions

We observed that B. melitensis isolates are susceptible to the majority of the tested antibiotics. Furthermore, minocycline and sparfloxacin exhibited extremely high bactericidal effects in relation to the B. melitensis isolates. The sensitivity of commonly used drugs for the treatment of brucellosis should be regularly monitored. To the best of our knowledge, this is the first report of rifampin and cotrimoxazole resistant isolates of B. melitensis in China. In summary, based on the findings from this study, we suggest that antibiotic administration and use should be rationalized to prevent future drug resistance.

Tetracycline and rifampicin induced a viable but nonculturable state in Staphylococcus epidermidis biofilms

AIM

The goal of this study was to determine the effectiveness of antibiotics on Staphylococcus epidermidis biofilms with different proportions of dormant bacteria, using clinical and commensal isolates.

MATERIALS & METHODS

The ability of S. epidermidis isolates to develop a dormant state was determined. The susceptibility of biofilms with prevented or induced dormancy to antibiotics was evaluated by enumeration of viable and cultivable cells, and confocal microscopy.

RESULTS

Dormancy was observed in the majority of tested strains. Tetracycline and rifampicin enhanced the development of a viable but noncultivable biofilm state.

CONCLUSION

Biofilms with induced dormancy were more likely to survive rifampicin. Furthermore, we found that the reduction of cultivable cells was not sufficient to reach definite conclusions on antimicrobial effectiveness.

Prevenção da formação de biofilmes em marcapassos artificiais: é viável?

Resumo Objetivo: Identificar os agentes antimicrobianos utilizados na prevenção da formação de biofilme em marcapassos artificiais. Métodos: Revisão da literatura para responder a seguinte questão: “Quais agentes antimicrobianos são usados para prevenir a formação de biofilmes em marcapassos artificiais?” As bases de dados PubMed, Web of Science, Scopus, Science Direct, Cochrane, CINAHL, Embase e LILACS foram consultadas em todos os idiomas sem restrição de tempo. Resultados: A amostra final apresentou cinco estudos primários, sendo a maioria experimental. As investigações identificaram agentes com potencial para a redução ou inibição da formação de biofilmes em marcapassos. Destacou-se a associação de agentes físico-químicos e farmacológicos aos agentes antimicrobianos. Conclusão: A prevenção da formação de biofilmes em marcapassos é viável. Os agentes mais promissores para obter este efeito foram a rifampicina, AIGIS®, a formulação aquosa neobactrim e a cobertura com trimetilsilano e oxigênio em superfícies tratadas com plasma.

Does Extracellular DNA Production Vary in Staphylococcal Biofilms Isolated From Infected Implants versus Controls?

BACKGROUND

Prosthetic implant infections caused by Staphylococcus aureus and epidermidis are major challenges for early diagnosis and treatment owing to biofilm formation on the implant surface. Extracellular DNA (eDNA) is actively excreted from bacterial cells in biofilms, contributing to biofilm stability, and may offer promise in the detection or treatment of such infections.

QUESTIONS/PURPOSES

(1) Does DNA structure change during biofilm formation? (2) Are there time-dependent differences in eDNA production during biofilm formation? (3) Is there differential eDNA production between clinical and control Staphylococcal isolates? (4) Is eDNA production correlated to biofilm thickness?

METHODS

We investigated eDNA presence during biofilm formation in 60 clinical and 30 control isolates of S aureus and S epidermidis. The clinical isolates were isolated from patients with infections of orthopaedic prostheses and implants: 30 from infected hip prostheses and 30 from infected knee prostheses. The control isolates were taken from healthy volunteers who had not been exposed to antibiotics and a hospital environment during the previous 3 and 12 months, respectively. Control S epidermidis was isolated from the skin of the antecubital fossa, and control S aureus was isolated from the nares. For the biofilm experiments the following methods were used to detect eDNA: (1) fluorescent staining with 4',6-diamidino-2-phenylindole (DAPI), (2) eDNA extraction using a commercial kit, and (3) confocal laser scanning microscopy for 24-hour biofilm observation using propidium iodide and concanavalin-A staining; TOTO^®-1 and SYTO^® 60 staining were used for observation and quantification of eDNA after 6 and 24 hours of biofilm formation. Additionally antibiotic resistance was described.

RESULTS

eDNA production as observed by confocal laser scanning microscopy was greater in clinical isolates than controls (clinical isolates mean ± SD: 1.84% ± 1.31%; control mean ± SD: 1.17% ± 1.37%; p < 0.005) after 6 hours of biofilm formation. After 24 hours, the amount of eDNA was greater in biofilms of S epidermidis than in biofilms of S aureus (S aureus mean ± SD: 1.35% ± 2.0%; S epidermidis mean ± SD: 6.42% ± 10.6%; p < 0.05). Clinical isolates of S aureus and S epidermidis produced more eDNA than control isolates at 6 hours of biofilm formation. The extraction method also showed that clinical isolates produced substantially greater amounts of eDNA than controls.

CONCLUSIONS

S aureus and S epidermidis exhibit a differential production of DNA with time. Clinical isolates associated with implant infections produce greater amounts of eDNA than controls. Future research might focus on the diagnostic value of eDNA as a surrogate laboratory marker for biofilm formation in implant infections.

CLINICAL RELEVANCE

eDNA should be considered as a potential future diagnostic tool or even a possible target to modify biofilms for successful treatment of biofilm-associated infections.

In vitro drug resistance of clinical isolated Brucella against antimicrobial agents

OBJECTIVE

To explore the antibiotic resistance of Brucella melitensis and instruct rational use of antimicrobial agents in clinical treatment of Brucella infection.

METHODS

Bacteria were cultured and identified by BACTEC9120 and VITEK II automicrobic system. E-test was used to detect the minimal inhibitory concentration (MIC) of antimicrobial agents in the drug susceptivity experiment.

RESULTS

A total of 19 brucella strains (all Brucella melitensis) were isolated from 19 patients, who had fever between January 2010 and June 2012, and 17 samples were blood, one was bone marrow, the other sample was cerebrospinal fluid. The MIC range of ceftazidime was 2.0-8.0 mg/L, rifampicin was 0.06-2.0 mg/L, amikacin was 4.0-12.0 mg/L, levofloxacin was 2.0-8.0 mg/L, doxycycline was 8.0-32.0 mg/L, sulfamethoxazole-trimethoprim was 4.0-16.0 mg/L, ampicillin was 1.5-2.0 mg/L and gentamicin was 0.50-0.75 mg/L.

CONCLUSIONS

The drugs used in this experiment cover common drugs for treating Brucella. Meanwhile, the results are consistent with clinical efficacy. It is suggested personalized regimen according to patients' status in treatment of Brucella.

Antibiofilm agents and implant-related infections in orthopaedics: where are we?

Orthopaedics is currently the largest market of biomaterials worldwide and implant-related infections, although relatively rare, remain among the first reasons for joint arthroplasty and osteosynthesis failure. Bacteria start implant infection by adhering to biomaterials and producing biofilms, which represent a major reason for bacterial persistence, in spite of antibiotic treatment and host's defence. In the last two decades, a number of different antibiofilm agents have been studied and both in vitro and in vivo results appear now promising, even if their effective role in orthopaedics remains to be assessed. In this review, we introduce an original classification of antibiofilm agents, based on their mechanism of action and examine the available data concerning their possible application to orthopaedic implant-related infections. Molecules that interfere with biofilm production (biofilm prevention agents) include anti-adhesion compounds, quorum sensing inhibitors, non-steroideal anti-inflammatory drugs, and antimicrobial peptides; N-acetylcysteine and specific enzymes promise the greatest therapeutic possibilities by disrupting established biofilms (biofilm disrupting agents). The identification of antimicrobials able to bypass the biofilm barrier (biofilm bypassing agents), and antibiofilm vaccines are further strategies aimed to reduce the impact of biofilm-related infections, opening new pathways in controlling implant-related infections. However, this review shows that still insufficient knowledge is currently available as to regard the efficacy and safety of the investigated antibiofilm strategies to treat infection that involve bone tissue and biomaterials commonly implanted in orthopaedics, pointing out the need for further research in this promising field.

New approaches for treating staphylococcal biofilm infections

Bacteria of the genus Staphylococcus are a prominent cause of acute and chronic infections. The ability of the staphylococci to establish biofilms has been linked to the persistence of chronic infections, which has drawn considerable interest from researchers over the past decade. Biofilms can be defined as sessile communities of surface-attached cells encased in an extracellular matrix, and treatment of bacteria in this mode of growth is challenging due to the resistance of biofilm structures to both antimicrobials and host defenses. In this review of the literature, we introduce Staphylococcus aureus and Staphylococcus epidermidis biofilms and summarize current antibiotic treatment approaches for staphylococcal biofilm infections. We also review recent studies on alternative strategies for preventing biofilm formation and dispersing established biofilms, including matrix-degrading enzymes, small-molecule approaches, and manipulation of natural staphylococcal disassembly mechanisms. While research on staphylococcal biofilm development is still in its early stages, new discoveries in the field hold promise for improved therapies that target staphylococcal biofilm infections.

New Trends in Diagnosis and Control Strategies for Implant Infections

In implant infections, a quick and reliable identification of the etiological agent is crucial to realizing efficacious therapies. Among molecular methods, automated ribotyping has proven to be an accurate and rapid technique. More recently, MALDI-TOF/MS and PCR-electrospray ionization (ESI)/ MS have been applied successfully to microbiological diagnosis. In implant infections, biofilm is still the major problem for bacterial persistence and recalcitrance to antibiotic therapy. Among biofilm-disrupting agents, enzymes promise the greatest therapeutic possibilities. DNase I degrades biofilm extracellular DNA and has been shown to sensitize biofilm to various biocides and anionic detergents, while dispersin B acts on biofilm exopolysaccharide and, combined with antiseptic, gives a broad-spectrum antibiofilm and antimicrobial activity. The novel antimicrobial approach based on photodynamic treatment (PDT) applies, in combination with antibiotics, to the implant or medical devices reachable by optical fibers. Better progress could be gained by the development of infection-resistant biomaterials able to both inhibit bacterial adhesion and promote tissue integration. New knowledge regarding the fibronectin-mediated internalization of Staphylococcus aureus by osteoblasts, and on its role in the pathogenesis of implant-related osteomyelitis, paves the way for the development of vaccines against staphylococcal adhesins, to prevent both adhesion on biomaterials and bacterial invasion of bone cells.