Subcutaneous Taenia crassiceps Cysticercosis in a Ring-Tailed Lemur (Lemur catta) in a Serbian Zoo

BACKGROUND

Different rodent species serve as natural intermediate hosts for carnivore tapeworm Taenia crassiceps. However, this cestode occasionally infects various dead-end hosts including humans and other primates and may cause serious pathological implications with potentially fatal outcome. In this paper, we present subcutaneous cysticercosis caused by T. crassiceps, found in a previously healthy 17-years-old male ring-tailed lemur (Lemur catta) in a Serbian Zoo.

CASE PRESENTATION

The animal was presented to a veterinarian with a history of periarticular subcutaneous swelling in medial right knee region. After fine needle aspiration revealed cycticerci-like structures, a surgery was performed for complete extraction of the incapsulated multicystic mass containing numerous cysticerci. Collected material was sent for parasitological, histological and molecular analysis. One month after surgery, the lemur died due to respiratory failure unrelated to cysticercosis. Based on morphological features of large and small hooks and characteristic proliferation of cysticerci, a metacestode of T. crassiceps was identified, which was confirmed after sequencing of obtained amplicons and comparing them to the GenBank database.

CONCLUSIONS

This is one of the few reported cases of T. crassiceps cysticercosis in a ring-tailed lemur, and the first one in Serbia. This endangered species seem to be more sensitive for T. crassiceps than other non-human primates, which represents serious conservation challenge for captive animals. Due to zoonotic nature of the parasite, challenging diagnosis, severity of the disease, difficult treatment and possible fatalities, high biosecurity measures are of particular importance, especially in endemic regions.

The first record of mcr-1 gene for colistin resistance in pigs from Serbia: should we be worried?

Colistin is being used as a last-resort drug to treat infections caused by multidrug-resistant (MDR) bacteria in humans. In veterinary medicine, colistin has been used for the treatment and prevention of infectious diseases. In the first study of mcr genes by multiplex PCR in healthy pigs from Serbia, we discovered mcr-1 in 4.85% out of 350 fecal samples. The presence of mcr-1 gene was detected on three farms located less than 100 km apart from each other, predominantly in piglet samples. The results point to the necessity of monitoring of colistin resistance and the mcr genes in food producing animals as well as restricting colistin usage on farms.

Subtyping Blastocystis in pigs and humans revealed unusual avian-specific subtype ST6 in humans in Serbia

Blastocystis is a common protist colonizing the gastrointestinal tract of humans and various animals. The first subtyping of Blastocystis isolates in pigs and humans in Serbia revealed unusual avian-specific subtype ST6 in humans. In total, 48 pig faecal specimens collected on seven pig farms and 50 human faecal specimens positive to Blastocystis by microscopic examination were selected for the study. Eleven randomly selected PCR-positive pig samples and 10 samples from human patients (with gastrointestinal complaints) were subjected to SSU rDNA sequencing. Three subtypes were identified (ST3, ST5 and ST6) by phylogenetic analysis. ST5 was found in all pig samples; while in human samples, we detected ST3 and ST6. The latter subtype is relatively uncommon in Europe and highly adapted to avian hosts; therefore, the possibility of sporadic zoonotic transmission to human patients should not be ignored.

SALMONELLA CONTROL IN POULTRY PRODUCTION AND RESISTANCE MONITORING IN SERBIA

A new regulation on Salmonella control in Serbia has been implemented recently. The main goal is to eliminate two most common serovars, Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) from the poultry farms and to keep the infections caused by these bacteria under control. Experimental work conducted in the past decade in our Institute provided evidence that Salmonella is transmitted easily in a flock and is hard to be eliminated from the farms and hatcheries. This is in good agreement with the published research work by other authors. It is also evident that good management practice and vaccination strategy must be implemented in poultry production. Therefore a simple questionnaire for poultry producers and hatchery experts to provide a quick overview of the management practice was designed in order to find out shortcomings. Salmonella monitoring must be conducted by applying bacteriological examination while serology control is efficient more during exploitation and less during rearing. However, it was found out that bacteriology and serology can be successfully combined in order to estimate the infection status. Although regular bacteriological screening for salmonella is compulsory, some farmers in the country do not pursue this type of analysis at the recommended frequency. Subsequently, those who send the samples for bacteriological examination more often seem to have more salmonella related problems. The most frequent finding of salmonella was in the chickens that died during transportation and the first three days of life and from paper pads. Extremely rare finding of salmonella was in breeding eggs and even rarer in table eggs. If environmental samples from commercial layers are positive, serology testing is recommended. Salmonella isolated from chickens and farm premises in Serbia were susceptible to most antimicrobials tested. Multiple resistances was quite seldom but approximately 20% of the isolates were quinolone resistant. The resistance to fluoroquinolones was not detected. However, Salmonella highly resistant to nalidixic acid with MIC (minimal inhibitory concentration) to NAL > 512 mg/ml were less susceptible to ciprofloxacin, although MICs to CIP were still below the CLSI recommended breakpoint (R > 4 mg/ml). Similar reports were obtained in investigation of salmonella isolated from human stool and the research indicates that the most frequent serovar in the country in humans, food and poultry include Salmonella Enteritidis, Salmonella Typhimurium and Salmonella Infantis.

Avian pathogenic Escherichia coli: diagnosis, virulence and prevention

Avian pathogenic Escherichia coli (APEC) causes colibacillosis within poultry flocks all around the world. There is a number of virulence mechanisms involved in the disease process in poultry and determination of some of the responsible genes is important for diagnosis of colibacillosis. In this work, research data regarding diagnostics of APEC and how certain clonal lineages could cause infection in different hosts is presented. In order to determine virulence genotype of APEC, multiplex polymerase chain reaction, based on a published sequence of seven pairs of primers (iroN, ompT, hlyF, iss, iutA, elitC and cvaC), was used in our laboratory. It was established in the research of other scientists that isolates with two or more of these genes can develop pathogenic phenotype, while isolates with one or none of the genes are mostly commensal E. coli. Additionally, virulence mechanisms in APEC were also briefly described. It was emphasized that resistance genes and virulence genes are sometimes co-located on the same plasmid and that such plasmids could be shared among related or unrelated bacteria species. Since APEC often confers resistance to antibiotics, the therapy is less effective in poultry with multidrug resistant strains. It was concluded that good management practice, treatment with probiotics and/or vaccination are necessary to reduce colibacillosis outbreaks. This approach is even more pronounced since APEC resides in intestine of healthy poultry and could cause disease if poultry is exposed to various stressors.

GENETIC MECHANISMS OF METHICILLIN RESISTANCE IN STAPHYLOCOCCUS AUREUS (MRSA) AND ITS CAPACITY OF TRANSMISSION: A BRIEF REVIEW

Methicillin-resistant Staphylococcus aureus is one of the most important human pathogens. Th ese bacteria have the ability to colonize animals andcross species barriers. Th ree major groups of MRSA strains have emerged. Healthcare associated MRSA and community acquired MRSA strains have potential to spread worldwide and oft en persist in hospitals and communities as clonal strains. Th e livestock-associated MRSA has been isolated from healthy human carriers but also from infected patients all around the world. Molecular typing of staphylococcal cassette chromosome mec (SCCmec), multilocus sequence typing in combination with pulse fi eld gel electrophoresis and spa typing are most frequently used for genetic characterization of MRSA strains. Th e community-acquired MRSA strains are capable of producing Panton Valentine leukocidin (PVL) cytotoxin which is their major virulence determinant. MRSA strains possess a number of virulence factors that are common in other bacteria and it is still not entirely explained which virulence factors or mechanisms of their regulation are important for the pathogenic potential, persistence in the environment or the ability to cause detrimental infection in patients. Recently, as a contribution to the progress of molecular biology, peculiar mechanisms of genetic regulation of virulence genes have been discovered and their role in pathogenesis of infection and epidemiology of MRSA has been studied.

THE ROLE OF EFFLUX PUMP AND OTHER MECHANISMS OF ANTIMICROBIAL RESISTANCE TO (FLUORO)QUINOLONES IN EPIDEMIC ISOLATES OF SALMONELLA TYPHIMURIUM, SALMONELLA KENTUCKY AND SALMONELLA INFANTIS

This paper briefly describes mechanisms of resistance to fluoroquinolones in several worldwide distributed Salmonella clones. The isolates have acquired multiple resistance traits over the years due to extensive antibiotic treatment both in human and veterinary medicine. Except for the Salmonella Typhimuirum DT104 where effl ux pump appears to play a major role in resistance to (fluoro)quinolones, in other serovars mutations on topoisomerase genes seem to fi rstly occur and have been primary mechanisms of resistance. Plasmid borne resistance is rarely detected but because of horizontal gene transfer needs to be recorded. Understanding the genetic events at the molecular level is crucial in epidemiology work and provides insight in spreading of resistance clones of Salmonella.

Clonal spread of Salmonella enterica serovar Infantis in Serbia: acquisition of mutations in the topoisomerase genes gyrA and parC leads to increased resistance to fluoroquinolones

Quinolone-resistant Salmonella Infantis (n = 64) isolated from human stool samples, food and poultry during the years 2006-2011 were analysed for their resistance phenotypes, macrorestriction patterns and molecular mechanisms of decreased susceptibility to fluoroquinolones. Minimum inhibitory concentrations (MICs) of nalidixic acid (NAL) and ciprofloxacin (CIP) were determined by the agar dilution procedure, and the susceptibility to additional antimicrobial agents was determined by the disc diffusion method. To assess the influence of enhanced efflux activity, MICs were determined in the presence and absence of the inhibitor PAβN. The results of pulsed-field gel electrophoresis (PFGE) typing revealed that quinolone-resistant S. Infantis in Serbia had similar or indistinguishable PFGE profiles, suggesting a clonal spread. All S. Infantis showed combined resistance to NAL and tetracycline, whereas multiple drug resistance to three or more antibiotic classes was rare (2 isolates of human origin). The MICs ranged between 512 and 1024 μg/mL for NAL and 0.125-2 μg/mL for CIP. A single-point mutation in the gene gyrA leading to a Ser83→Tyr exchange was detected in all isolates, and a second exchange (Ser80→Arg) in the gene parC was only present in eight S. Infantis isolates exhibiting slightly higher MICs of CIP (2 μg/mL). The inhibitor PAβN decreased the MIC values of CIP by two dilution steps and of NAL by at minimum 3-6 dilution steps, indicating that enhanced efflux plays an important role in quinolone resistance in these isolates. The plasmid-mediated genes qnr, aac(6')-lb-cr and qepA were not detected by PCR assays.

PLASMID MEDIATED RESISTANCE TO QUINOLONES IN SALMONELLA

Plasmid mediated resistance to quinolones in Salmonella enterica is briefly presented. World wide spread of qnr determinants is evident, indicating the necessity for prudent use of antimicrobials in human and veterinary medicine. In discovering plasmid mediated resistance to quinolones antimicrobial resistance monitoring for β-lactam antibiotics is helpful, since their target genes frequently coexist in plasmid. Nevertheless, 100% reliable method for screening of qnr determinants has not been discovered. The finding of qnr genes and other determinants from the large collection of Salmonella isolates in respective national laboratories, in several countries is described. Individual cases of qnr positive Salmonella from patients, reported in recent years, are also presented.

[Sensitivity of bacteria to antimicrobial drugs and interpretation of results]

INTRODUCTION

The discovery of antimicrobial drugs was a turning point in the permanent conflict between the mankind and microorganisms. However, due to the wide use and misuse of antibiotics in therapy and prophylaxis of infections the mankind is threatened by an alarming rise in the resistance of bacteria to drugs. Will this phenomenon turn us back to the pre-antibiotic era?

DISCUSSION

The increasing resistance of bacteria has become a global public health problem: bacteria are showing a remarkable capacity to develop different mechanisms and avoid drug effect. Mechanisms of resistance are numerous and various: production of beta-lactamases (Ambler class A): TEM-I, TEM-2 and SHV-1 and mutants of classical enzymes with extended spectrum (ESBL) (e.g. in Klebsiella spp.) which results in the resistance to the 3rd generation cephalosporines and new metallo-beta-lactamases among Pseudomonas and Acinetobacter (resistance to carbapenems). The alteration of the target enzymes (PBP) leads to the Staphylococci resistance to methicillin and the responsible gene is mecA gene). The alteration of DNA gyrase due to the mutations of gyrA, gyrB, parC genes (accumulation of multiple mutations) results in the development of resistance to fluoroquinolones); and the active efflux system - "pumping out" of the drug from the bacterial cell leads to the resistance of a wide spectrum of different antibiotics. In order to choose the most efficient drug for therapy, it is necessary to investigate susceptibility of bacteria to antimicrobial agents. For that purpose, a disc-diffusion method according to CLSl standard procedure is performed. For invasive strains it is often necessary to determine minimal inhibitory concentrations (MIC) of antimicrobials. The methods that are in use are agar-dilution methods, E-test and automated MIC determination by VITEK 2 system.

CONCLUSION

By molecular-biological methods it is possible to identify the mechanisms of resistance and detect the specific genes behind it (mecA gene). The targeted therapy prevents compromising of antibiotics valuable in treatment of severe infections (carbapenems).

Significance of screening tests in diagnosis of infectious mononucleosis

The investigation included 91 patients in who an acute or previous EBV infection was established by ELISA test. All patients were also subjected to the Paul-Bunnell-Davidsohn test, while 20 patients were tested by the rapid screening test Clearview IM. The diagnosis of acute infective mononucleosis was in 61 patients (67%) confirmed by the Elisa test, and in 12 patients (19.67%) by the Paul-Bunnell-Davidsohn test, while the rapid screening test Clearview IM demonstrated too low a detection of heterophile antibodies. The rapid screening test was not reliable. In 25% cases, the test was invalid, at early infection stages the rapid test failed to diagnose any case of the EBV virus infection. Paul-Bunell-Davidsohn was often negative, especially with young children. Therefore, priority should be given to virology tests based on the detection of specific antibodies to EBV antigen.

[Analysis of the plasmid profile of various Salmonella serotypes]

INTRODUCTION

Every year foodborne infections cause millions of illnesses but many of them go undiagnosed and unreported. The epidemiology of these illnesses is changing, new pathogens have emerged (Escherichia coli O157:H7, Cyclospora cayetanensis, Vibrio vulnificus). Salmonella spp. is the most common bacterial cause of acute enterocolitis with us. All over the world, as well as in our country the most often isolated serotype is Salmonella Enteritidis. A great problem in many countries is the multiresistant Salmonella Typhimurium, as well as other serotypes resistant to a great number of antimicrobial drugs (S. Hadar, S. Typhi). Clinical microbiologists are often asked to determine the relatedness of bacterial isolates. Recently, traditional methods of strain typing such as bacteriophage typing, resistotyping and serotyping, have been supplemented or replaced in many laboratories with newer molecular methods such as plasmid fingerprinting, ribotyping. PCR-based methods, etc. The goal of strain typing is to provide evidence that epidemiologically related isolates collected during an outbreak are also genetically related and thus represent the same strain.

MATERIAL AND METHODS

In the laboratory for Enterobacteriaceae of the Institute of Public Health Novi Sad in the four year period (1995-1998) 3659 primary isolates of Salmonella spp. were isolated using standard bacteriological methods (cultural, biochemical and serological examination). For certain strain of Salmonella Enteritidis, S. Typhimurium and S. Hadar susceptibility to antimicrobial agents was tested by disc-diffusion test (Kirby-Bauer) and plasmid profiles were analyzed. Plasmid DNA was extracted by Birnboim and Doly alkaline lysis method and plasmid bands were separated by electrophoresis in agarose gel.

RESULTS

In the period of 1995-1998 the most common serotype isolated was Salmonella Enteritidis with 3017 (82.5%) of the total number of isolated Salmonellas; S. Typhimurium 203 (5.5%), S. Hadar 118 (3.2%). Plasmid profiles were tested in 10 S. Enteritidis isolates that originated from patients with sporadic cases of diarrhea. All investigated strains had one plasmid band with molecular weight of 38 MDa. All isolates were susceptible to all antibiotics tested. Ten isolates of S. Hadar originated from one outbreak from food samples and stools of patients with diarrheal disease and from the worker in the restaurant. All isolates were resistant to ampicillin and streptomycin, and plasmid profile analysis showed 5 plasmid bands with molecular weights of 13, 5.4, 4.2, 2.0 and 1.7 MDa. Chosen strains of S. Typhimurim were not epidemically related. Strains number 1, 3, 4, 5 were susceptible to all antibiotics tested, and had only one plasmid of 50 MDa, strain number 7 was resistant to streptomycin and had 2 plasmid bands of 50 and 1.7 MDa, other strains were multiresistant and had different plasmid profiles with 4-7 plasmid bands with molecular weights ranging from 50-1.4 MDa.

CONCLUSION

Plasmid profile analysis is not a sufficient method for examination of Salmonella Enteritidis which is the most common cause of enterocolitis with us. It is, however, a helpful method for proving epidemiological and clonal relatedness of Salmonella isolates that are resistant to antimicrobial agents and have a great number of plasmids (such as some strains of S. Typhimurim and S. Hadar).

[Shigellae isolated in 1997--plasmid profiles and antibiotic resistance]

INTRODUCTION

Shigella spp is one of the most frequently isolated bacteria causing acute diarrhea with us. Genetics of pathogenicity of Shigella spp. includes chromosomal and plasmid genes. Most virulence factors are coded by invasion plasmid antigen genes residing on a 180-230 MDa plasmid. There is a big problem with multiple resistance of Shigella spp. strains, which is mostly plasmid-borne. Genetic analysis of bacterial cells, that is plasmid profile analysis, is important for investigation of sources and ways of spreading of the infection. All isolates originating from the same clone have identical plasmid profiles, i.e. number and size of plasmids. The aim of the investigation was: comparing the type of resistance to antimicrobical agents found in epidemic and nonepidemic. Shigella strains isolated in 1997, analyzing plasmid profiles of these isolates and confirming their epidemic connection.

MATERIAL AND METHODS

Susceptibility to antibiotics was examined by a standard disc-diffusion method. Plasmid profiles of 40 strains (20 from the outbreak and 20 from sporadic cases) were tested using a method of alkaline lysis by Birnboim and Doly followed by electrophoresis in agarose gel.

RESULTS

Shigella strains were resistant to antimicrobial agents which are most commonly used. Epidemic isolates shared the same resistance type, they were resistant to cephalexin, streptomycin and co-trimoxazole. The dominant type of resistance of nonepidemic strains was to ampicillin, streptomycin and co-trimoxazole. Strains isolated during the outbreak had identical plasmid profiles (2 plasmid bands of 55 and 1.5 MDa). Non-epidemic isolates had different plasmid profiles as well as type of resistance.

CONCLUSION

Strains of Shigella spp. isolated during an outbreak had the same type of resistance and the same plasmid profiles, which indicated their origin from the same clone. The plasmid profile analysis is a reliable and precise method for determination of epidemic connection of Shigella isolates.