Comparison of an improved RAPD fingerprinting with different typing methods for discriminating clinical isolates of Staphylococcus spp

Reservoirs of Staphylococcus spp. and Streptococcus spp. Associated with Intramammary Infections of Dairy Cows

To design cost-effective prevention strategies against mastitis in dairy cow farms, knowledge about infection pathways of causative pathogens is necessary. Therefore, we investigated the reservoirs of bacterial strains causing intramammary infections in one dairy cow herd. Quarter foremilk samples (n = 8056) and milking- and housing-related samples (n = 251; from drinking troughs, bedding material, walking areas, cow brushes, fly traps, milking liners, and milker gloves), were collected and examined using culture-based methods. Species were identified with MALDI-TOF MS, and selected Staphylococcus and Streptococcus spp. typed with randomly amplified polymorphic DNA-PCR. Staphylococci were isolated from all and streptococci from most investigated locations. However, only for Staphylococcus aureus, matching strain types (n = 2) were isolated from milk and milking-related samples (milking liners and milker gloves). Staphylococcus epidermidis and Staphylococcus haemolyticus showed a large genetic diversity without any matches of strain types from milk and other samples. Streptococcus uberis was the only Streptococcus spp. isolated from milk and milking- or housing-related samples. However, no matching strains were found. This study underlines the importance of measures preventing the spread of Staphylococcus aureus between quarters during milking.

Strain diversity and infection durations of Staphylococcus spp. and Streptococcus spp. causing intramammary infections in dairy cows

To effectively prevent and control bovine mastitis, farmers and their advisors need to take infection pathways and durations into account. Still, studies exploring both aspects through molecular epidemiology with sampling of entire dairy cow herds over longer periods are scarce. Therefore, quarter foremilk samples were collected at 14-d intervals from all lactating dairy cows (n = 263) over 18 wk in one commercial dairy herd. Quarters were considered infected with Staphylococcus aureus, Streptococcus uberis, or Streptococcus dysgalactiae when ≥100 cfu/mL of the respective pathogen was detected, or with Staphylococcus epidermidis or Staphylococcus haemolyticus when ≥500 cfu/mL of the respective pathogen was detected. All isolates of the mentioned species underwent randomly amplified polymorphic DNA (RAPD)-PCR to explore strain diversity and to distinguish ongoing from new infections. Survival analysis was used to estimate infection durations. Five different strains of Staph. aureus were isolated, and the most prevalent strain caused more than 80% of all Staph. aureus infections (n = 46). In contrast, 46 Staph. epidermidis and 69 Staph. haemolyticus strains were isolated, and none of these caused infections in more than 2 different quarters. The 3 most dominant strains of Strep. dysgalactiae (7 strains) and Strep. uberis (18 strains) caused 81% of 33 and 49% of 37 infections in total, respectively. The estimated median infection duration for Staph. aureus was 80 d, and that for Staph. epidermidis and Staph. haemolyticus was 28 and 22 d, respectively. The probability of remaining infected with Strep. dysgalactiae or Strep. uberis for more than 84 and 70 d was 58.7 and 53.5%, respectively. Staphylococcus epidermidis and Staph. haemolyticus were not transmitted contagiously and the average infection durations were short, which brings into question whether antimicrobial treatment of intramammary infections with these organisms is justified. In contrast, infections with the other 3 pathogens lasted longer and largely originated from contagious transmission.

Investigations on Transfer of Pathogens between Foster Cows and Calves during the Suckling Period

Simple Summary

Regarding the increasing importance of alternative calf rearing systems, such as the foster cow system, better knowledge about the transfer of pathogens via suckling calves would be very helpful. In this context, the present study was conducted on a large organic dairy farm practising calf rearing on foster cows. For microbiological examinations, quarter milk samples were collected both from foster cows and biological dams. Additionally, swabs were taken from the oral cavities of the associated foster calves. The concordance of pathogens between cows and calves was further examined by strain comparisons. The same strains of isolates were detected for Pasteurella multocida, Staphylococcus aureus, S. sciuri and Streptococcus (Sc.) suis. Based on the present results and the available literature, transmission of P. multocida and S. aureus via suckling calves is considered very likely. Transmission of pathogens from the dam to the foster cow with the suckling calf as a vector could not be detected.

Abstract

To date, there have been few studies on the health effects of foster cow systems, including the transmission of mastitis-associated pathogens during suckling. The present study aimed to compare the pathogens detected in the mammary glands of the foster cow with those in the oral cavities of the associated foster calves and to evaluate the resulting consequences for udder health, calf health and internal biosecurity. Quarter milk sampling of 99 foster cows from an organic dairy farm was conducted twice during the foster period. Oral cavity swabs were taken from 345 foster calves. Furthermore, quarter milk samples were collected from 124 biological dams to investigate possible transmission to the foster cows via the suckling calves. All samples were microbiologically examined and confirmed by MALDI-TOF (matrix-assisted laser desorption time-of-flight mass-spectrometry). Using RAPD-PCR (randomly amplified polymorphic DNA polymerase chain reaction), strain similarities were detected for Pasteurella multocida, Staphylococcus aureus, S. sciuri and Streptococcus (Sc.) suis. Transmission of P. multocida and S. aureus probably occurred during suckling. For S. sciuri and Sc. suis, environmental origins were assumed. Transmission from dam to foster cow with the suckling calf as vector could not be clearly demonstrated.

Current methodologies on genotyping for nosocomial pathogen methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in hospitals and the community. As the rapid spread and wide distribution of antimicrobial resistance (such as MRSA), treatment for infectious diseases caused by microorganisms has become a vital threat. Thus, early identification and genotyping are essential for further therapeutic treatment and the control of rapid expansion of MRSA. In combination with applications and data feedbacks, this review focused on the currently available molecular-based assays on their utility and performance for rapid typing of MRSA, especially on effective molecular-based methods. Besides, a common mobile element SCCmec and prevalence of HA-MRSA, LA-MRSA and CA-MRSA were introduced in this review in order to provide a more complete profile of MRSA.

Experimental nasal colonization of piglets with methicillin-susceptible and methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus sequence type (ST)398 is widely spread among livestock. People in contact with livestock have a higher risk of testing positive for MRSA. Several experimental settings have been described to study in vivo colonization of MRSA in pigs, each having its own limitations. The aim of this study was to develop a nose-colonization model in pigs to quantitatively study the colonization of MRSA and the co-colonization of MSSA and MRSA. Two experiments were performed: in the first experiment piglets received an intranasal inoculation with MRSA ST398, spa-type t011, and in the second experiment piglets received an intranasal inoculation with two MSSA strains (ST398, spa-type t011 and t034) and two MRSA strains (also ST398, spa-type t011 and t034) to investigate co-colonization. Colonization was quantitatively monitored for 2 weeks in both experiments. Nasal colonization was successfully established in all piglets with stable numbers of S. aureus between 10(4) and 10(6) CFU. MSSA and MRSA were able to co-colonize.

Small colony variant of methicillin-resistant Staphylococcus pseudintermedius ST71 presenting as a sticky phenotype

We first observed the phenomenon of small colony variants (SCVs) in a Staphylococcus pseudintermedius sequence type 71 (ST71) strain, isolated from a non-pet owner. Although we found that small-sized colonies share main features with Staphylococcus aureus SCVs, they nevertheless show a novel, particular, and sticky phenotype, whose expression was extremely stable, even after subcultivation.

Methicillin-resistant Staphylococcus pseudintermedius infection in a bone marrow transplant recipient

Staphylococcus pseudintermedius is a veterinary pathogen that has seldom been described as an agent of human disease. Features of this probably underreported coagulase-positive Staphylococcus species are depicted here through the description of a graft-versus-host disease-related wound infection caused by a multidrug-resistant strain.

Multiple-locus variable number tandem repeat analysis of Staphylococcus aureus: comparison with pulsed-field gel electrophoresis and spa-typing

Background

Molecular typing of methicillin-resistant Staphylococcus aureus (MRSA) is required to study the routes and rates of transmission of this pathogen. Currently available typing techniques are either resource-intensive or have limited discriminatory ability. Multiple-locus variable number tandem repeat analysis (MLVA) may provide an alternative high throughput molecular typing tool with high epidemiological resolution.

Methodology/Principal Findings

A new MLVA scheme for S. aureus was validated using 1681 S. aureus isolates collected from Dutch patients and 100 isolates from pigs. MLVA using 8 tandem repeat loci was performed in 2 multiplex PCRs and the fluorescently labeled PCR products were accurately sized on an automated DNA sequencer. The assessed number of repeats was used to create MLVA profiles consisting of strings of 8 integers that were used for categorical clustering. MLVA yielded 511 types that clustered into 11 distinct MLVA complexes which appeared to coincide with MLST clonal complexes. MLVA was at least as discriminatory as PFGE and twice as discriminatory as spa-sequence typing. There was considerable congruence between MLVA, spa-sequence typing and PFGE, at the MLVA complex level with group separation values of 95.1% and 89.2%. MLVA could not discriminate between pig-related MRSA strains isolated from humans and pigs, corroborating the high degree of relationship. MLVA was also superior in the grouping of MRSA isolates previously assigned to temporal-spatial clusters with indistinguishable SpaTypes, demonstrating its enhanced epidemiological usefulness.

Conclusions

The MLVA described in this study is a high throughput, relatively low cost genotyping method for S. aureus that yields discrete and unambiguous data that can be used to assign biological meaningful genotypes and complexes and can be used for interlaboratory comparisons in network accessible databases. Results suggest that MLVA offsets the disadvantages of other high discriminatory typing approaches and represents a promising tool for hospital, national and international molecular epidemiology.

Interaction of Staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes

This study focuses on the interaction of Staphylococcus epidermidis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p < or = 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.

The differentiation of Carnobacterium divergens using the random amplification of polymorphic DNA polymerase chain reaction technique

The potential of the randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) technique to differentiate Carnobacterium divergens from other members of the genus Carnobacterium was examined. A numerical analysis of the genomic profiles obtained demonstrated that it was possible to differentiate the C. divergens strains from other Carnobacterium strains using this technique. The heterogeneity observed in the representatives of the species C. piscicola adds further weight to the suggestion in other taxonomic studies that subspecies of this species exist.

Single primer polymerase chain reaction fingerprinting for Pasteurella multocida isolates from laboratory rabbits

OBJECTIVE

To evaluate a rapid polymerase chain reaction (PCR) fingerprinting technique for discriminating among Pasteurella multocida isolates from laboratory rabbits.

SAMPLE POPULATION

33 P multocida isolates from rabbits with clinical pasteurellosis.

PROCEDURE

PCR assays were conducted with 2 minisatellites (core sequence and modified core sequence of phage M13) and 2 microsatellites ([GTG]5 and [GACA]4). Each bacterium was assigned to a PCR type for each of the primers used. Boiled bacterial extracts and purified genomic DNA were compared by use of PCR assays for phage M13 and (GACA)4. Plasmids were isolated from each bacterium, and their influence on PCR fingerprint was determined, using boiled extracts as a DNA source.

RESULTS

M13 core sequence and M13 modified core sequence yielded 5 and 8 PCR types, respectively. The microsatellites (GTG)5 and (GACA)4 yielded 4 and 9 PCR fingerprint types, respectively. Fingerprint patterns obtained by use of isolated DNA differed from those obtained by use of boiled extracts, although discrimination among P multocida isolates was similar. The presence or absence of plasmids did not affect PCR fingerprints.

CONCLUSION

Single primer PCR fingerprinting with minisatellite and microsatellite primers is an efficient and reproducible method for the discrimination of P multocida isolates from rabbits and can be performed directly, using boiled bacterial extracts as a source of template, although more bands were obtained from pure genomic DNA.

Identification of mRNAs differentially expressed in lymphocytes following interleukin-2 activation

We investigated genes involved in the interleukin-2 activation of cultured lymphocytes using a differential display reverse transcription PCR technique. Three cDNA fragments corresponding to mRNAs differentially amplified in the activated lymphocytes were sequenced and identified. These fragments were identical to the 3' region of the mRNAs encoding for the tumor rejection antigen TRA 1 that is the human homologue of the murine heat shock protein gp96, the DAP12 protein that possesses an immunoreceptor tyrosine-based activation motif, and the human motor protein p87/89 expressed in the heart. These proteins are involved, respectively, in cellular communication, in signal transduction, and in cellular movements. Our findings suggest that the activation of cellular immune response by interleukin-2 is a process analogous to other known phenomena of activation of catabolic reactions of energy transduction for activities which allow adaptation of cells to stress conditions.

Molecular characterization of epidemic multiresistant Staphylococcus haemolyticus isolates

Fifty-five Staphylococcus haemolyticus specimens isolated from patients and neonatal intensive care unit staff were tested for susceptibility to 12 antimicrobial agents. There were 34 multidrug-resistant isolates which were resistant to oxacillin, ampicillin, cefazolin, cefmetazole, imipenem, and gentamicin. These isolates had a higher frequency of resistance to tobramicin and ofloxacin, and relatively high MICs (2 to 4 micrograms/mL) for vancomycin, although none of the isolates were vancomycin resistant. To investigate hospital-acquired colonization and infection by multiresistant S. haemolyticus, we examined all isolates by pulsed-field gel electrophoresis (PFGE) after SmaI and SstII digestion, and detected an endemic PFGE pattern in multiresistant isolates. The results suggested that local spread of multiresistant S. haemolyticus was hospital acquired, and that the hospital staffs functioned as a reservoir.