Biotypes and antimicrobial susceptibilities of Brucella isolates

Construction of recombinant Omp25 or EipB protein loaded PLGA nanovaccines for Brucellosis protection

Safe and effective vaccine candidates are needed to address the limitations of existing vaccines against Brucellosis, a disease responsible for substantial economic losses in livestock. The present study aimed to encapsulate recombinant Omp25 and EipB proteins, knowledged antigen properties, into PLGA nanoparticles, characterize synthesized nanoparticles with different methods, and assessed theirin vitro/in vivoimmunostimulatory activities to develop new vaccine candidates. The recombinant Omp25 and EipB proteins produced with recombinant DNA technology were encapsulated into PLGA nanoparticles by double emulsion solvent evaporation technique. The nanoparticles were characterized using FE-SEM, Zeta-sizer, and FT-IR instruments to determine size, morphology, zeta potentials, and polydispersity index values, as well as to analyze functional groups chemically. Additionally, the release profiles and encapsulation efficiencies were assessed using UV-Vis spectroscopy. After loading with recombinant proteins, O-NPs reached sizes of 221.2 ± 5.21 nm, while E-NPs reached sizes of 274.4 ± 9.51 nm. The cumulative release rates of the antigens, monitored until the end of day 14, were determined to be 90.39% for O-NPs and 56.1% for E-NPs. Following the assessment of thein vitrocytotoxicity and immunostimulatory effects of both proteins and nanoparticles on the J774 murine macrophage cells,in vivoimmunization experiments were conducted using concentrations of 16µg ml-1for each protein. Both free antigens and antigen-containing nanoparticles excessively induced humoral immunity by increasing producedBrucella-specific IgG antibody levels for 3 times in contrast to control. Furthermore, it was also demonstrated that vaccine candidates stimulated Th1-mediated cellular immunity as well since they significantly raised IFN-gamma and IL-12 cytokine levels in murine splenocytes rather than IL-4 following to immunization. Additionally, the vaccine candidates conferred higher than 90% protection from the infection according to challenge results. Our findings reveal that PLGA nanoparticles constructed with the encapsulation of recombinant Omp25 or EipB proteins possess great potential to triggerBrucella-specific humoral and cellular immune response.

Prevalence of Brucella melitensis and Brucella abortus Fluoroquinolones Resistant Isolates: A Systematic Review and Meta-Analysis

Background: Brucellosis impact both animals and humans worldwide. However, using antibiotics for brucellosis remains controversial despite decades of research. Relapse can complicate treatment in this area. Since the mid-1980s, microbiologists, and physicians have studied fluoroquinolones' use for treating human brucellosis. The principal advantages of fluoroquinolones are their intracellular antimicrobial activity, low nephrotoxicity, good pharmacokinetics, and the lack of drug-level monitoring. Fluoroquinolones inhibit disease recurrence. In vitro and clinical data were used to study the prevalence of Brucella melitensis and Brucella abortus fluoroquinolone-resistant isolates. Methods: The PubMed, Scopus, Embase, and Web of Science databases were carefully searched until August 6, 2022, for relevant papers. The number of resistant isolates and sample size were used to estimate the proportion of resistant isolates, fitting a model with random effects, and DerSimonian-Laird estimated heterogeneity. Furthermore, meta-regression and subgroup analyses were used to assess the moderators to identify the sources of heterogeneity. Meta-analysis was performed using R software. Results: Forty-seven studies evaluated fluoroquinolone resistance in Brucella spp. Isolates. Fluoroquinolones have shown high in vitro efficacy against Brucella spp. The resistance rates to ofloxacin, sparfloxacin, fleroxacin, pefloxacin, and lomefloxacin were 2%, 1.6%, and 4.6%, respectively. Conclusion: Clinical in vitro tests demonstrated that fluoroquinolones can eradicate Brucella spp. Owing to first-line medication resistance, recurrence, and toxicity, it is essential to standardize the Brucella antimicrobial susceptibility test method for a more precise screening of resistance status. Fluoroquinolones are less resistant to fluoroquinolone-based treatments in modern clinical practice as alternatives to standard therapy for patients with brucellosis relapse after treatment with another regimen and in patients who have developed toxicity from older agents.

Prevalence of Brucella melitensis and Brucella abortus tetracyclines resistance: A systematic review and meta-analysis

INTRODUCTION

Brucellosis is a zoonotic disease that can be transmitted from animals to humans. Brucellosis is caused by bacteria of the genus Brucella, which are typically transmitted through contact with infected animals, unpasteurized dairy products, or airborne pathogens. Tetracyclines (tetracycline and doxycycline) are antibiotics commonly used to treat brucellosis; however, antibiotic resistance has become a major concern. This study assessed the worldwide prevalence of tetracycline-resistant Brucella isolates.

METHODS

A systematic search was conducted in Scopus, PubMed, Web of Science, and EMBASE using relevant keywords and Medical Subject Headings (MeSH) terms until August 13, 2022, to identify relevant studies for meta-analysis. A random effects model was used to estimate the proportion of resistance. Meta-regression analysis, subgroup analysis, and examination of outliers and influential studies were also performed.

RESULTS

The prevalence rates of resistance to tetracycline and doxycycline were estimated to be 0.017 (95% confidence interval [CI], 0.009-0.035) and 0.017 (95%CI, 0.011-0.026), respectively, based on 51 studies conducted from 1983 to 2020. Both drugs showed increasing resistance over time (tetracycline: r = 0.077, P = 0.012; doxycycline: r = 0.059, P = 0.026).

CONCLUSION

The prevalence of tetracycline and doxycycline resistance in Brucella was low (1.7%) but increased over time. This increase in tetracycline and doxycycline resistance highlights the need for further research to understand resistance mechanisms and develop more effective treatments.

The perspective of antibiotic therapeutic challenges of brucellosis in the Middle East and North African (MENA) countries: Current situation and therapeutic management

Brucellosis is among the most prevalent zoonotic infections in Middle Eastern and North African (MENA) countries, critically impacting human and animal health. A comprehensive review of studies on antibiotic susceptibility and therapeutic regimes for brucellosis in ruminants and humans in the MENA region was conducted to evaluate the current therapeutic management in this region. Different scientific databases were searched for peer-reviewed original English articles published from January 1989 to February 2021. Reports from research organizations and health authorities have been taken into consideration. Brucella melitensis and Brucella abortus have been reported from the majority of MENA countries, suggesting a massive prevalence particularly of B. melitensis across these countries. Several sporadic cases of brucellosis relapse, therapeutic failure, and antibiotic resistance of animal and human isolates have been reported from the MENA region. However, several studies proved that brucellae are still in-vitro susceptible to the majority of antibiotic compounds and combinations in current recommended WHO treatment regimens, e.g. levofloxacin, tetracyclines, doxycycline, streptomycin, ciprofloxacin, chloramphenicol, gentamicin, tigecycline, and trimethoprim/sulfamethoxazole. The current review presents an overview on resistance development of brucellae and highlights the current knowledge on effective antibiotics regimens for treating human brucellosis. This article is protected by copyright. All rights reserved.

Investigation of antibiotic susceptibilities of Brucella Strains isolated from various clinical samples in eastern Turkey

Background

Brucellosis is a worldwide zoonotic disease that causes serious public health problems. This study aimed to identify Brucella strains isolated from various clinical samples by conventional and molecular methods and to determine antimicrobial susceptibilities against doxycycline (DOX), streptomycin (STR), ciprofloxacin (CIP) and rifampicin (RIF) by the gradient strip (E test) test method.

Methods

A total of 87 Brucella strains isolated from various clinical specimens between 2004 and 2018 were included in this study. While four of the 87 strains included in the study were identified only at the genus level, the remaining 83 strains were identified at the species level by the Real-Time Multiplex PCR (M-RT-PCR) method and conventional methods were used for biotyping.

Results

According to molecular identification results, 83 strains were identified as B. melitensis by the M-RT-PCR method, with 82 strains identified as Brucella melitensis biovar (bv) 3 and one as B. melitensis bv 1 according to the conventional biotyping method. Among the antibiotics studied, CIP was found to be the most active agent according to the minimum inhibitory concentrations (MIC)₉₀ values. This was followed by DOX and STR, respectively. While all of the isolates were sensitive to CIP, DOX and STR, 18 (20.7%) strains were found to be moderately susceptible to RIF, with the highest values of MIC₅₀ and MIC₉₀.

Conclusions

In our study, all strains were identified as B. melitensis. DOX, STR, CIP and RIF used in the treatment of brucellosis were found to be effective.

Brucella melitensis and Brucella abortus genotyping via real-time PCR targeting 21 variable genome loci

Brucella melitensis and Brucella abortus account for almost all cases of brucellosis in Turkish population. We developed a fourplex quantitative real-time PCR (qPCR) assay for the electrophoresis-free, rapid and cost-effective differentiation of B. abortus and B. melitensis from the other Brucella spp. The 4-plex species differentiation assay was combined with a qPCR assay targeting 17 different single nucleotide polymorphism (SNP) loci in Brucella genomes. This combination resulted in a 21 Variable Genome Loci (21-VGL) qPCR assay for high resolution genotyping of B. abortus and B. melitensis. A total of 486 Brucella was analyzed using the qPCR assay to create a 21-VGL profile database. The database contained the profiles of 55 B. abortus, 352 B. melitensis, 3 B. ceti, 6 B. neotomae, 7 B. ovis, 6 B. pinnipedialis, 44 B. suis and 13 B. canis strains. The 21-VGL Brucella genotyping clearly distinguished B. abortus, B. melitensis, B. neotomae and B. ovis. The 21-VGL approach could not distinguish B. pinnipedialis from B. ceti and some B. suis genotypes from B. canis. The results revealed that more than 99% of the Brucella isolates in Turkey were B. melitensis and 21-VGL genotyping can be reduced to 8-VGL B. melitensis genotyping without any loss of genotyping resolution. To our knowledge, we introduced the fastest and the lowest-cost B. abortus and B. melitensis genotyping and species differentiation methodology in the literature.

Ceftriaxone use in brucellosis: A case series

Background

Brucellosis is a zoonotic disease caused by Brucella spp. It can be either uncomplicated or complicated when it disseminates to other organs. Treatment for brucellosis involves a combination of at least two antibiotics, or more in complicated brucellosis. Limited data exist on the use of ceftriaxone in the clinical setting. Therefore, we present patient cases in which ceftriaxone was used in brucellosis treatment regimen.

Methods

Patients with documented brucellosis from January 2008 to December 2018 were evaluated for the use of ceftriaxone for treatment in King Abdulaziz Univeristy Hospital, Jeddah, Saudi Arabia. Patients’ data were evaluated retrospectively and are described.

Results

Out of 94 treated brucellosis patients, six patients received ceftriaxone 2 g IV every 12 h for therapy for varied durations. Four had neurobrucellosis, one had Brucella epididymo-orchitis and one had uncomplicated brucellosis. All six patients experienced clinical cure, though one neurobrucellosis patient had complications and one had ceftriaxone stopped after one week of therapy due to presumed antibiotic-induced fever.

Conclusion

Ceftriaxone represents a reasonable option for the treatment of complicated brucellosis when added to the initial regimen at a dose of 2 g IV every 12 h.

In vitro activity of Brucella melitensis isolates to various antimicrobials in Turkey

BACKGROUND

Brucellosis is a systemic infectious disease caused by Brucella bacteria. A successful treatment requires antibiotics that can penetrate into the cell at high concentrations. The aim of this study was to assess the biotype and in vitro activity of 80 Brucella isolates obtained from blood against various antimicrobials for human brucellosis in Turkey.

METHODS

Identification of the types of the species designated Brucella species was made using the polymerase chain reaction (PCR), with type-specific primers. Serotyping was performed using mono-specific A and M antisera. The minimum inhibitory concentrations (MICs) of antibiotics known to have good intracellular penetration (doxycycline, rifampicin, ofloxacin, levofloxacin, moxifloxacin, clarithromycin, and azithromycin) were determined by the agar dilution method.

RESULTS

All of the 80 Brucella isolates were determined to be Brucella melitensis: 75 B. melitensis biotype 3 (93.7%) and 5 B. melitensis biotype 1 (6.3%). Doxycycline was the most effective among the tested antibiotics against Brucella species (MIC(50)-MIC(90), 0.25-0.5 μg/ml), and it was followed by levofloxacin (MIC(50)-MIC(90), 0.5-1 μg/ml), moxifloxacin (MIC(50)-MIC(90), 1-1 μg/ml), ofloxacin (MIC(50)-MIC(90), 1-1 μg/ml), rifampicin (MIC(50)-MIC(90), 2-4 μg/ml), azithromycin (MIC(50)-MIC(90), 4-8 μg/ml), and clarithromycin (MIC(50)-MIC(90), 8-32 μg/ml), respectively.

CONCLUSIONS

The in vitro activity of doxycycline and rifampicin, which are used in the classic treatment of brucellosis, was found to be very good. Quinolones were found to have in vitro activity against Brucella isolates. Among the macrolides, azithromycin had a higher level of activity compared with clarithromycin. A combination of quinolones and azithromycin could be an alternative to doxycycline and rifampicin in the treatment of brucellosis.

Genotyping of human Brucella melitensis biovar 3 isolated from Shanxi Province in China by MLVA16 and HOOF

Background

Brucellosis presents a significant economic burden for China because it causes reproductive failure in host species and chronic health problems in humans. These problems can involve multiple organs. Brucellosis is highly endemic in Shanxi Province China. Molecular typing would be very useful to epidemiological surveillance. The purpose of this study was to assess the diversity of Brucella melitensis strains for epidemiological surveillance. Historical monitoring data suggest that Brucella melitensis biovar 3 is the predominant strain associated with the epidemic of brucellosis in Shanxi Province.

Methods/Principal Findings

Multiple-locus variable-number repeat analysis (MLVA-16) and hypervariable octameric oligonucleotide fingerprinting (HOOF-print) were used to type a human-hosted Brucella melitensis population (81 strains). Sixty-two MLVA genotypes (discriminatory index: 0.99) were detected, and they had a genetic similarity coefficient ranging from 84.9% to 100%. Eighty strains of the population belonged to the eastern Mediterranean group with panel 1 genotypes 42 (79 strains) and 43 (1 strain). A new panel 1 genotype was found in this study. It was named 114 MLVAorsay genotype and it showed similarity to the two isolates from Guangdong in a previous study. Brucella melitensis is distributed throughout Shanxi Province, and like samples from Inner Mongolia, the eastern Mediterranean genotype 42 was the main epidemic strain (97%). The HOOF-printing showed a higher diversity than MLVA-16 with a genetic similarity coefficient ranging from 56.8% to 100%.

Conclusions

According to the MLVA-16 and HOOF-printing results, both methods could be used for the epidemiological surveillance of brucellosis. A new genotype was found in both Shanxi and Guangdong Provinces. In areas with brucellosis, the MLVA-16 scheme is very important for tracing cases back to their origins during outbreak investigations. It may facilitate the expansion and eradication of the disease.

Identification and in vitro antimicrobial susceptibility of Brucella species isolated from human brucellosis

Brucellosis is a world-wide zoonotic disease with a major impact on the public health. Due to the high risk of laboratory acquired infection, limited laboratory investigations were performed on this organism, including detailed identification and susceptibility study. Brucella melitensis is the commonest aetiological agent for human brucellosis in this region. The in vitro susceptibility pattern against selected antimicrobial agents was assessed using E-test. All isolates were noted to be sensitive to all the antimicrobial agents tested except for rifampicin where elevated MIC > 1 μg/mL was noted in 30 out of 41 isolates tested.

Efficacy evaluation of some antibiotics against syrian brucella spp isolates, in vitro

Brucellosis is an endemic zoonosis in Syria, affecting large numbers of animals and there are an increasing number of cases in humans. The aim of this study is to investigate the in vitro efficacy of various traditional and new antibiotics against 89 Brucella isolates (isolated from domestic animals) collected from different Syrian regions. Minimum inhibitory concentrations (MICs) of seventeen antibiotics were determined. Ciprofloxacin and ofloxacin were the most effective antibiotics, whereas sparfloxacin, levofloxacin, doxycycline and tetracycline had a moderate activity. In contrast, moxifloxacin and rifampicin had a low activity, while streptomycin, spiramycin and cephalosporines were ineffective. As a result, we come to the conclusion that a combination between one effective quinolone and doxycycline has a good efficacy against Brucella. Further in vivo studies are necessary to support this suggestion.

Identification and determination of antibiotic susceptibilities of Brucella strains isolated from patients in van, Turkey by conventional and molecular methods

PURPOSE

Brucellosis is a worldwide zoonotic disease and still constitutes a major public health problem. In this study, we aimed to identify biovars of Brucella strains isolated from clinical specimens taken from brucellosis patients from the Eastern Anatolia region as well determine the susceptibility of these isolates to tigecycline and azithromycin, drugs that may serve as alternatives to the conventional drugs used in the therapy.

MATERIALS AND METHODS

Seventy-five Brucella spp. isolates were included in the study. All strains were identified by both conventional and molecular methods. Brucella Multiplex PCR kit (FC-Biotech, Code: 0301, Turkey) and B. melitensis biovar typing PCR kit (FC-Biotech, Code: 0302, Turkey) were used for molecular typing. Antimicrobial susceptibilities of all strains were determined by E-tests.

RESULTS

By conventional biotyping, 73 strains were identified as B. melitensis biovar 3 and two strains as B. abortus biovar 3. Molecular typing results were compatible with conventional methods. The MIC50 and MIC90 values of doxycycline were 0.047 and 0.094; tigecycline 0.094 and 0.125; trimethoprim/sulfamethoxazole 0.064 and 0.19; ciprofloxacin 0.19 for both; streptomycin 0.75 and 1; rifampin 1 and 2 and azithromycin 4 and 8. According to the MIC values, doxycycline was found to be the most effective antibiotic, followed by tigecycline, trimethoprim-sulfamethoxazole and ciprofloxacin.

CONCLUSION

Currently recommended antibiotics for the treatment of brucellosis such as doxycycline, rifampin, streptomycin, trimethoprim-sulfamethoxazole and ciprofloxacin were found to be still effective. While our results showed that tigecycline can be used an alternative agent in the treatment of brucellosis, azithromycin has not been confirmed as an appropriate agent for the treatment.

In vitro antibiotic susceptibility testing of Brucella isolates from Egypt between 1999 and 2007 and evidence of probable rifampin resistance

Background

Brucellosis poses a significant public health problem in Mediterranean countries, including Egypt. Treatment of this disease is often empirical due to limited information on the antibiotic susceptibility profiles of Brucella spp. in this region of the world. The aim of this study was to determine the antibiotic susceptibility profiles of Brucella blood isolates in Egypt, a country endemic for brucellosis.

Methods

Brucella spp. isolates were identified from the blood cultures of acute febrile illness (AFI) patients presenting to a network of infectious disease hospitals from 1999–2007. Minimum inhibitory concentrations were determined for tetracycline, gentamicin, doxycycline, trimethoprim-sulfamethoxazole, streptomycin, ceftriaxone, ciprofloxacin and rifampin using the E-test. Interpretations were made according to Clinical and Laboratory Standards Institute (CLSI) guidelines.

Results

A total of 355 Brucella spp. isolates were analyzed. All were susceptible to tetracycline, doxycycline, trimethoprim-sulfamethoxazole, streptomycin and ciprofloxacin; probable resistance to rifampin and ceftriaxone was observed among 277 (64%) and 7 (2%) of the isolates, respectively. Percentages of isolates showing probable resistance to rifampin were significantly lower before 2001 than in the following years (7% vs. >81%, p < 0.01).

Conclusions

Despite the high burden of brucellosis in Egypt and frequent empirical treatment, isolates have remained susceptible to the majority of tested antibiotics. However, this is the first report of high rates of probable resistance to rifampin among Brucella isolates from Egypt. Patients should be closely monitored while following standard treatment regimens. Continued surveillance, drug susceptibility studies and updated CLSI interpretive criteria are needed to monitor and update antibiotic prescribing policies for brucellosis.

Brucellosis in Turkey -- an overview

Although almost a century has gone by since its first description in the country, Turkey has not been able to eradicate brucellosis, which remains a major public health problem. In this review, we give an overview of the epidemiological and epizootic status of brucellosis in Turkey. Although little readily accessible data concerning the epidemiology of brucellosis in Turkey are available, the limited official and published data were analyzed. Despite being endemic in Turkey, brucellosis remains under-diagnosed and under-reported. Adherence to traditional farming practices and lifestyles and the consumption of fresh dairy produce contribute to the high incidence of brucellosis. The successful implementation of a national brucellosis control program requires strong political will, good funding, and collaboration, especially between the public health and veterinary sectors. Primary healthcare workers should always keep the symptoms of acute and chronic brucellosis in mind when treating patients.

Efficacy and tolerability of antibiotic combinations in neurobrucellosis: results of the Istanbul study

No data on whether brucellar meningitis or meningoencephalitis can be treated with oral antibiotics or whether an intravenous extended-spectrum cephalosporin, namely, ceftriaxone, which does not accumulate in phagocytes, should be added to the regimen exist in the literature. The aim of a study conducted in Istanbul, Turkey, was to compare the efficacy and tolerability of ceftriaxone-based antibiotic treatment regimens with those of an oral treatment protocol in patients with these conditions. This retrospective study enrolled 215 adult patients in 28 health care institutions from four different countries. The first protocol (P1) comprised ceftriaxone, rifampin, and doxycycline. The second protocol (P2) consisted of trimethoprim-sulfamethoxazole, rifampin, and doxycycline. In the third protocol (P3), the patients started with P1 and transferred to P2 when ceftriaxone was stopped. The treatment period was shorter with the regimens which included ceftriaxone (4.40 ± 2.47 months in P1, 6.52 ± 4.15 months in P2, and 5.18 ± 2.27 months in P3) (P = 0.002). In seven patients, therapy was modified due to antibiotic side effects. When these cases were excluded, therapeutic failure did not differ significantly between ceftriaxone-based regimens (n = 5/166, 3.0%) and the oral therapy (n = 4/42, 9.5%) (P = 0.084). The efficacy of the ceftriaxone-based regimens was found to be better (n = 6/166 [3.6%] versus n = 6/42 [14.3%]; P = 0.017) when a composite negative outcome (CNO; relapse plus therapeutic failure) was considered. Accordingly, CNO was greatest in P2 (14.3%, n = 6/42) compared to P1 (2.6%, n = 3/117) and P3 (6.1%, n = 3/49) (P = 0.020). Seemingly, ceftriaxone-based regimens are more successful and require shorter therapy than the oral treatment protocol.

Treatment protocol and relapses of brucella endocarditis; cotrimoxazole in combination with the treatment of brucella endocarditis

Antibiotic treatment, surgical intervention and postoperative antibiotic regimens are recommended for the treatment of brucella endocarditis (BE). Our clinical antibiotic regimens involve a triple antibiotic regimen for treating BE before the operation. The combination of three antibiotics is continued for at least six months and until the titres of the Wright serologic test are diminished to 1:160 levels. In this study, our aim was to evaluate the effects of combined medical and surgical treatments on survival and relapse rates in the periods of mid to late terms. We investigated 13 patients who were treated between January 1993 and June 2009. Our clinical observations led us to use a combination of rifampicin (900 mg twice a day), streptomycin (12 to 16 mg/kg/24 h intramuscularly) and doxycycline (200 mg/kg twice a day); rifampicin, tetracycline (8 mg/kg three times a day) and cotrimoxazole (15 mg/kg twice a day) or rifampicin, doxycycline and cotrimoxazole regimen for treating BE before the operation. This treatment should be continued for at least six months after surgery in order to prevent relapses.

Multiple-locus variable-number tandem-repeat analysis genotyping of human Brucella isolates from Turkey

A multiple-locus variable-number tandem-repeat analysis (MLVA) was applied to investigate the epidemiological relationship and genetic diversity among 162 human Brucella isolates collected from all geographic regions of Turkey in an 8-year period (2001 to 2008). The isolates were genotyped by using an MLVA assay developed in Orsay, France (MLVA-16(Orsay)) including eight minisatellite (panel 1) and eight microsatellite (panel 2, subdivided into 2A and 2B) markers. Panels 1 and 2A distinguish 14 genotypes; two of these represented 85% of the strains. Panel 2B displayed a very high discriminatory power. Three loci from panel 2B had diversity index values higher than 0.74. MLVA-16(Orsay) yielded 105 genotypes; 73 were represented by a unique isolate, and 32 included two to eight isolates. The isolates from different patients within the same outbreak or from the same patient before first-line therapy and after relapse showed identical genotypes. A number of MLVA genotypes appeared to be partially restricted to some geographic areas and displayed no annual variation, possibly reflecting persistence of genotypes in certain areas for a time span of at least a decade. This study, representing the first molecular typing results of human Brucella isolates from Turkey, indicated that Turkish human Brucella melitensis isolates were most closely related to the neighboring countries' isolates included in the East Mediterranean group.

Antimicrobial susceptibilities of Brucella isolates from various clinical specimens

PURPOSE

Brucellosis is a worldwide zoonotic disease and still constitutes a major public health problem. In the study we claimed to identify Brucella species from clinical samples of patients with active brucellosis from Van region of Eastern Anatolia and to determine in vitro antimicrobial susceptibilities of these strains to commonly used anti-Brucella agents and a possible new alternative tigecycline.

MATERIALS AND METHODS

A total of 56 Brucella isolates were enrolled the study and the identification of the isolates were based on conventional methods. In vitro activities of antimicrobials were evaluated by the E test method.

RESULTS

All isolates were identified as B. melitensis. MIC(90) values of doxycycline, streptomycin, rifampin, trimethoprim-sulfamethoxazole and tigecycline were 0.064 mg/L, 1 mg/L, 2 mg/L, 0.125 mg/L and 0.094 mg/L, respectively. Tigecycline had low MIC(50) and MIC(90) values against all B. melitensis strains; the highest MIC observed was 0.25 μg/mL.

CONCLUSION

Our data suggest that tigecycline can be a therapeutic alternative option for the treatment of brucellosis.

Tigecycline: Its potential for treatment of brucellosis

The in vitro efficacy and synergistic activity of tigecycline in comparison with other antimicrobials used in brucellosis, were tested for 16 Brucella melitensis strains by the E-test method. Tigecycline had the lowest minimal inhibitory concentration levels, and rifampin the highest, in the study. Tigecycline also provided the better synergistic activity compared to doxycycline according to the fractional inhibitory concentration index. The results of this in vitro study suggest tigecycline as a therapeutic alternative for brucellosis. These observations need to be supported with clinical studies.

Efficacy of ciprofloxacin versus doxycycline as prophylaxis against experimental murine Brucella melitensis infection

The prophylactic potential of ciprofloxacin was assessed in comparison with doxycycline, an established therapeutic antibiotic, to limit or control infection by Brucella melitensis in an experimental mouse model. Ciprofloxacin treatment reduced bacterial loads in the spleens of challenged mice when administered prior to or at the same time as the bacterial challenge. In comparison, doxycycline provided much greater reductions in bacterial counts, even when treatment was initiated after infection. Doxycycline was able to protect against B. melitensis when administered for 5 days from 24 h after infection and for at least 28 days after cessation of the antibiotic. Overall, these results confirm that ciprofloxacin is less effective than doxycycline but suggest that it may have some utility in providing protection against low-level infections. Combination studies are indicated.

A case of brucellosis with abscess of the iliacus muscle, olecranon bursitis, and sacroiliitis

Brucellosis is a systemic infection involving many organs and tissues. The musculoskeletal system is one of the most commonly affected. The disease can present with sacroiliitis, peripheral arthritis, spondylitis, paraspinal abscess, bursitis, and osteomyelitis. A 25-year-old male patient was admitted with fever of 20-day duration, right-sided hip pain, and night sweating. A Brucella standard tube agglutination test was positive at a titer of 1/160. Magnetic resonance imaging (MRI) of the hip joint showed right sacroiliitis and a hyperintense, nodular, lobulated mass within the right iliacus muscle, consistent with abscess. The patient was started on intramuscular streptomycin at a dose of 1 g/day, oral rifampin 600 mg/day, and doxycycline 200 mg/day. On day 20 of treatment, the patient was admitted with swelling and pain over the left elbow for the past week. MRI of the left elbow was performed, which showed fluid edema suggestive of olecranon bursitis. Taking the patient's complaints into consideration, rifampin and doxycycline treatment were maintained for a year. Pain at the hip joint and elbow resolved and MRI findings disappeared. Abscess of the iliacus muscle, which has not been reported before, and the olecranon bursitis that developed during treatment make this case worth presenting.

Rifampicin resistance phenotyping of Brucella melitensis by rpoB gene analysis in clinical isolates

R Rifampicin resistance of Brucella melitensis by rpoB gene analysis has not yet been performed in Turkey, where brucellosis is endemic. In this study, we investigated the efficacy of E-test and single nucleotide polymorphism (SNP) analysis of the B. melitensis rpoB gene, for the detection of mutations conferring rifampicin resistance, by sequencing 21 human B. melitensis strains from the Southeast and Marmara regions of Turkey. On CLSI slow-growing bacteria standards, all isolates were sensitive to rifampicin except for 6 which showed intermediate resistance to rifampicin. MIC(50) and MIC(90)values were 1 microg/ml and 1.5 microg/ml respectively (range 0.50 -1.5 microg/ml). The rifampicin-resistant phenotype was investigated at Cd 154 (GTT/TTT), Cd 526 (GAC/TAC, GAC/AAC, GAC/GGC), Cd 536 (CAC/CTC, CAC/TAC), Cd 539 (CGC/AGC), Cd 541 (TCG/TTG) and Cd 574 (CCG/CTG) of the rpoB gene in B. melitensis 16M and B115 strains, and in clinical isolates. No missense mutations were found in any of the B. melitensis isolates, which indicates that all isolates were rifampicin-susceptible. In conclusion, SNP analysis was useful as a molecular tool for rifampin resistance testing. Although resistance to rifampicin was not detected in our strains of B. melitensis; the presence of strains with intermediate resistance to rifampicin indicates that susceptibility testing should be performed periodically.

Effect of polymyxin B and environmental conditions on isolation of Brucella species and the vaccine strain RB51

Brucella are resistant to polymyxin B (PB), but their relative susceptibility to PB and its derivative, colistin (COL) has not been rigorously or systematically studied. Comparative susceptibility of Brucella reference strains, vaccine strain RB51, and Brucella isolates from marine mammals to these two cationic peptides were determined by Etest. Vast differences among Brucella species were found in susceptibility to both PB and COL. Brucella demonstrated similar pattern of relative susceptibility to PB as that of COL, but they were less susceptible to COL. Both B. melitensis and B. suis were the least susceptible to polymyxins and rough strains were more susceptible to both PB and COL than the smooth except for the BvrR mutant. Strains were generally less susceptible to PB when cultured in CO(2) rather than ambient air; some became more susceptible in acidified medium. Results show that environment cultural conditions must be considered when selecting for CO(2)-independent strains of Brucella especially the vaccine strain RB51 on selective media containing PB. Our observations extend basic knowledge of the differential resistance of Brucella to polymyxins.

In vitro synergistic activity of antibiotic combinations against Brucella melitensis using E-test methodology

The treatment of brucellosis is still problematic, because of high rates of treatment failure or relapses. As the microorganism is an intracellular pathogen, treatment requires combined regimens. However, limited existing data on in vitro combinations are avaliable for Brucellae. The aim of this study was to investigate the in vitro efficacy of various traditional and new antibiotic combinations against 16 Brucella melitensis strains. The combination effect of antimicrobial agents was evaluated by E-test synergy method to obtain a fractional inhibitory concentration (FIC) index. Co-Trimoxazole (SXT) and moxifloxocin (MXF) exhibited the lowest MIC, while Rifampin (RIF) had the highest MIC in the study. Combinations with RIF showed the best synergistic activity (100% of RIF-tetracycline (TET), and 87.5% of RIF-SXT). Synergistic activity was also detected at seven (43.7%) of ciprofloxocin (CIP)-SXT, four (25%) of TET-MXF, and two (12.5%) of TET-SXT combinations. The combinations that demonstrated additivity were TET-SXT, CIP-SXT and TET-MXF. Antagonism was observed only with the TET-Streptomycin (STR) combination in three strains (18.8%). Further work including randomized controlled clinical trials is required to fully evaluate the usefulness of these data.

Brucellosis: a retrospective evaluation of 99 cases and review of brucellosis treatment

This retrospective study was performed in two university hospitals between January 2002 and 2006. Ninety-nine brucellosis patients were included in the study. These patients were classified as acute (91), chronic (4) and relapse (4) according to their clinical presentations and serological tests. Brucella bacteria were isolated in the blood of 17 (17.2%) cases. The most frequent symptom and clinical sign was fever. The osteoarticular complications were found in 17 patients (17.2%). Four of them were complicated with epidural abscess the same time. Two (2.2%) had meningitis, two (2.2%) had epididymoorchitis, three (3.3%) had skin rashes and one (1.1%) had hepatitis. Three of the acute brucellosis patients were pregnant. Rifampin and doxycycline combination therapy had been administered to most of the patients with acute and relapse brucellosis. However, complicated and chronic brucellosis cases were given different treatment combinations. This study reviews brucellosis therapy choices.

Gonadal brucellar abscess: imaging and clinical findings in 3 cases and review of the literature

We report the cases of 3 patients with brucellar gonadal abscess who were examined with gray-scale and color Doppler sonography. In these 3 cases, sonography revealed a thick-walled avarian (n = 2) or testicular (n = 1) abscess. Duplex Doppler sonography indicated a low-resistance type of flow in all 3 patients. The diagnosis of brucellar gonadal abscess is difficult, because it may have a misleading tumor-like appearance. Awareness of the imaging findings of gonadal abscess in patients with brucellosis and correlation with the results of serologic testing can allow early diagnosis, especially in endemic areas.

Molecular epidemiological and antibiotic susceptibility characterization of Brucella isolates from humans in Sicily, Italy

Brucellosis is a serious problem in Sicily. Brucella melitensis was identified as the species most frequently isolated in humans in Italy. No data, however, are available about the molecular epidemiological characterization of Brucella isolates from humans. We have conducted this study to molecularly characterize clinical isolates of Brucella spp. and to evaluate their antimicrobial susceptibilities. Twenty Brucella isolates were studied. Differential growth characteristics and DNA polymorphisms such as the restriction patterns of the PCR-amplified omp2a and omp2b genes, rpoB nucleotide sequencing, and multiple-locus variable-number tandem repeat analysis of 16 loci (MLVA-16) were used to characterize the strains. In vitro antibiotic susceptibility was determined by the E-test method on two different agar media, and the results were compared. All isolates were identified as B. melitensis biovar 3. rpoB nucleotide sequence analysis allowed the identification of two different genotypes of B. melitensis biovar 3. On the other hand, the MLVA-16 typing assay recognized 17 distinct genotypes. All isolates were sensitive to all tested antibiotics (rifampin, doxycycline, ciprofloxacin, ceftriaxone, and trimethoprim-sulfamethoxazole), and the Mueller-Hinton agar plate is recommended for antibiotic susceptibility testing by the E-test method. Our findings identify B. melitensis biovar 3 as the etiological agent isolated in Sicily and encourage the use of both molecular methods, and in particular of the MLVA-16 assay, in epidemiological trace-back analysis. This study represents the first epidemiological data from molecular typing of Brucella strains circulating in Italy and, in particular, in eastern Sicily.

In vitro susceptibilities of Brucella melitensis isolates to eleven antibiotics

BACKGROUND

Brucellosis is an endemic disease present in many countries worldwide, but it is rare in Europe and North America. Nevertheless brucella is included in the bacteria potentially used for bioterrorism. The aim of this study was the investigation of the antibiotic susceptibility profile of brucella isolates from areas of the eastern Mediterranean where it has been endemic.

METHODS

The susceptibilities of 74 Brucella melitensis isolates derived from clinical samples (57) and animal products (17) were tested in vitro. The strains originate from Crete (59), Cyprus (10), and Syria (5). MICs of tetracycline, rifampicin, streptomycin, gentamicin, norfloxacin, ciprofloxacin, levofloxacin, trimethoprim/sulfamethoxazole, ampicillin, amoxicillin/clavulanic acid, and erythromycin were detected by E-test method. The NCCLS criteria for slow growing bacteria were considered to interpret the results.

RESULTS

All the isolates were susceptible to tetracycline, streptomycin, gentamicin, ciprofloxacin, norfloxacin, and levofloxacin. Two isolates presented reduced susceptibility to rifampicin (MIC value: 1.5 mg/l) and eight to SXT (MIC values: 0.75-1.5 mg/l). Erythromycin had the highest (4 mg/l) MIC90value and both norfloxacin and erythromycin the highest (1.5 mg/l) MIC50 value.

CONCLUSION

Brucella isolates remain susceptible in vitro to most antibiotics used for treatment of brucellosis. The establishment of a standardized antibiotic susceptibility method for Brucella spp would be useful for resistance determination in these bacteria and possible evaluation of bioterorism risks.

Antibiotic selection and resistance issues with fluoroquinolones and doxycycline against bioterrorism agents

Bacillus anthracis (anthrax), Yersinia pestis (plague), Francisella tularensis (tularemia), Coxiella burnetti (Q fever), and Brucella sp (brucellosis) are all potential bioterrorism agents. Their known virulence, potential lethality, and ability to develop resistance to known antibiotic treatments make these pathogens particularly dangerous. We reviewed the scientific literature by searching MEDLINE databases and published abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America from 1989-2005 for studies of each of these biologic agents with the specific aim of examining whether doxycycline or a fluoroquinolone should be stockpiled for mass-scale postexposure prophylaxis. An evidence-based approach was used to determine whether doxycycline or fluoroquinolones were efficacious (both in vitro and in vivo) against these biologic agents and to examine these drugs' respective susceptibility patterns and differences in cost, based on available data. Little published data are available on these pathogens, and much of the data are from studies that used older strains obtained from patient or animal sources in outbreaks decades ago. Doxycycline appears to show comparable minimum inhibitory concentrations to those of the fluoroquinolone class in most clinical and in vitro studies, perhaps with the exception of inhalation plague. Studies also suggest that development of antibiotic resistance is less likely to occur with doxycycline. Doxycycline is several-fold less expensive than most fluoroquinolones and appears to have similar efficacy in most scenarios based on clinical case studies and established Clinical and Laboratory Standards Institute (formerly known as the National Committee for Clinical Laboratory Standards) breakpoints for staphylococci. Therefore, doxycycline should be considered as a first-line antibiotic in the management of bioterrorism agents.

A complication of brucellosis: epididymoorchitis

BACKGROUND

Epididymoorchitis is the most frequent genitourinary complication of brucellosis.

METHODS

This prospective study was conducted between February 2001 and January 2004, prospectively. Male patients diagnosed with brucellosis were included in this study and evaluated for testicular involvement.

RESULTS

Epididymoorchitis was detected in 17 out of 134 (12.7%) male patients with brucellosis. Mean age of the patients was 36.9+/-7.1 years. Twelve patients (70.6%) had acute, four patients (23.5%) had subacute, and one patient (5.9%) had chronic brucellosis. The most common symptoms were scrotal pain (94%) and swelling (82%). Eleven patients had unilateral epididymoorchitis, four had unilateral orchitis and two had unilateral epididymitis. A testicular abscess was detected in one patient. Sperm analysis was performed on 14 patients. Five patients had aspermia and eight had oligospermia. Combined antibiotic therapy was started and continued for 6-8 weeks. Orchiectomy was required for two patients and granulomatous orchitis was detected in the resected specimens. Relapse occurred in only one patient. Three patients had permanent oligospermia and one patient had permanent aspermia after the antibiotic therapy. Younger age, high C-reactive protein level and blood culture positivity were statistically significant differences between the patients with and without epididymoorchitis.

CONCLUSIONS

Brucellosis should be considered in the diagnosis of scrotal diseases in endemic areas. A conservative approach is usually adequate for managing brucellar epididymoorchitis. However, infertility problems may develop in these patients. Well-designed further investigations are needed to explain the relationship between brucellar epididymoorchitis and infertility in man.

In vitro activities of various antimicrobials against Brucella melitensis strains in the Aegean region in Turkey

OBJECTIVE

To study in vitro activities of three quinolones (ciprofloxacin, levofloxacin, moxifloxacin), four macrolides (erythromycin, dirithromycin, azithromycin, clarithromycin) and doxycycline against 44 clinical isolates of Brucella melitensis.

MATERIALS AND METHODS

Forty-four B. melitensis strains were isolated from blood cultures of adult patients with acute brucellosis who were hospitalized in the clinical ward of the Department of Clinical Microbiology and Infectious Diseases. The minimum inhibitory concentrations (MICs) of the tested antimicrobials were measured by the agar dilution method. MIC90 and MIC50 values were defined as the lowest concentration of the antibiotic at which 90 and 50% of the isolates were inhibited, respectively.

RESULTS

Doxycycline (MIC50: 0.25 microg/ml, MIC90: 0.50 microg/ml) had the lowest MIC in vitro against the B. melitensis strains. Among the quinolones, ciprofloxacin and levofloxacin had similar activities (MIC50: 0.5 microg/ml, MIC90: 2 microg/ml), whereas MIC of moxifloxacin (MIC50: 1 microg/ml, MIC90: 8 microg/ml) was higher than both antibiotics in this group. Clarithromycin and azithromycin were the most active macrolides (MIC50: 8 microg/ml and MIC90: 32 microg/ml), followed by erythromycin (MIC50: 16 microg/ml, MIC90: 32 microg/ml) and dirithromycin (MIC50: 64 microg/ml and MIC90: 64 microg/ml).

CONCLUSION

The results indicate that the conventional agent doxycycline is more active than quinolones and macrolides against the B. melitensis in vitro.

Identification ofBrucella species isolated from proven brucellosis patients in Izmir, Turkey

In many parts of the world, brucellosis has significantly decreased, but it is still a problem in some regions of Turkey. Totally, 11 Brucella strains isolated from the blood cultures of patients with presumptive diagnosis of brucellosis were identified to species and biovar level. For species identification, (i) CO2 requirements of isolates; (ii) detection of urease activation; (iii) detection of H2S production; (iv) dye sensitivities (thionine and basic fuchsin); (v) susceptibility to Brucella phage and (vi) agglutination with monospecific antisera (A and M) were performed. Ten out of 11 isolates were identified as B. melitensis biovar 3 and one out of 11 were identified as B. melitensis biovar 1. The sensitivity of isolates to antibiotics was determined by the E-test. All isolates were found to be sensitive to doxycycline, rifampin, ciprofloxacin and cephtriaxone. Only one out of 11 isolates was found to be semi-sensitive to trimethoprim/sulfamethoxazole (cotrimoxazole).

Use of 16S rRNA gene sequencing for rapid confirmatory identification of Brucella isolates

Members of the genus Brucella are categorized as biothreat agents and pose a hazard for both humans and animals. Current identification methods rely on biochemical tests that may require up to 7 days for results. We sequenced the 16S rRNA genes of 65 Brucella strains along with 17 related strains likely to present a differential diagnostic challenge. All Brucella 16S rRNA gene sequences were determined to be identical and were clearly different from the 17 related strains, suggesting that 16S rRNA gene sequencing is a reliable tool for rapid genus-level identification of Brucella spp. and their differentiation from closely related organisms.