Assessing and analysing contamination of a dairy products processing plant by Staphylococcus aureus using antibiotic resistance and PFGE

A dairy product processing plant was studied for 2.5 years to examine contamination with Staphylococcus aureus and try to correlate the source of contamination. Cultures were submitted to an antibiotic susceptibility test (AST) and characterised by Pulsed-field Gel Electrophoresis (PFGE) analysis. Results showed that 35.2% (19/51) of food handlers were asymptomatic carriers of S. aureus, and that 90.4% (19/21) of raw milk sampled was contaminated. Staphylococcus aureus was isolated from only 10 samples among more than 3200 investigated dairy products. No S. aureus contamination was found on machinery. The AST analysis demonstrated sensitivity of tested S. aureus to oxacillin, cephalothin, vancomycin, gentamicin, and sulfamethoxazole/trimethoprim. AST analysis generated eight different phenotypic profiles, but did not allow us to identify the source of contamination in seven of ten final products. PFGE analysis proved to be a sensitive method as it generated 42 different DNA banding profiles among the 48 S. aureus investigated, demonstrating a lack of predominance of endemic strains in the plant, contrary to suggestions raised by antibiotic resistance typing. Based on PFGE genotyping, S. aureus strains isolated from four contaminated final products were similar to four S. aureus isolated from raw milk. Five final products contained S. aureus different from all other strains collected, and one showed similarity to a strain isolated from a food handler. These results suggest contamination by raw milk as the main source of contamination of the final dairy products.     

Frequency of nasal and wound isolates of Staphylococcus aureus associated with TSST-1 production in Jordanian population

A total of 110 Staphylococcus aureus isolates were obtained from nasal carriers and wound infections of Jordanian population. The isolates were identified by cultural and biochemical methods. The nasal carrier rate of S. aureus among individuals was 22.7%. In comparison with the nasal S. aureus isolates the wound isolates did not produce significantly more virulence factors except DNase. Toxic shock syndrome toxin-1 production was higher among the S. aureus nasal isolates (40%) as compared with the wound isolates (26%) detected by an ELISA method which proved to be uniformly more sensitive than the immunodiffusion optimal sensitivity plate (OSP) method.     

Rhesus macaques (Macaca mulatta) are natural hosts of specific Staphylococcus aureus lineages

Currently, there is no animal model known that mimics natural nasal colonization by Staphylococcus aureus in humans. We investigated whether rhesus macaques are natural nasal carriers of S. aureus. Nasal swabs were taken from 731 macaques. S. aureus isolates were typed by pulsed-field gel electrophoresis (PFGE), spa repeat sequencing and multi-locus sequence typing (MLST), and compared with human strains. Furthermore, the isolates were characterized by several PCRs. Thirty-nine percent of 731 macaques were positive for S. aureus. In general, the macaque S. aureus isolates differed from human strains as they formed separate PFGE clusters, 50% of the isolates were untypeable by agr genotyping, 17 new spa types were identified, which all belonged to new sequence types (STs). Furthermore, 66% of macaque isolates were negative for all superantigen genes. To determine S. aureus nasal colonization, three nasal swabs from 48 duo-housed macaques were taken during a 5 month period. In addition, sera were analyzed for immunoglobulin G and A levels directed against 40 staphylococcal proteins using a bead-based flow cytometry technique. Nineteen percent of the animals were negative for S. aureus, and 17% were three times positive. S. aureus strains were easily exchanged between macaques. The antibody response was less pronounced in macaques compared to humans, and nasal carrier status was not associated with differences in serum anti-staphylococcal antibody levels. In conclusion, rhesus macaques are natural hosts of S. aureus, carrying host-specific lineages. Our data indicate that rhesus macaques are useful as an autologous model for studying S. aureus nasal colonization and infection prevention.     

Survey and properties of Staphylococcus aureus isolated from Japanese-style desserts

We surveyed the contamination of 315 Japanese- and western-style desserts and 247 human hands by Staphylococcus aureus and other staphylococcal bacteria. The most frequently isolated staphylococcal bacterium was S. warneri, followed by S. aureus. Only 1.9% of western-style desserts were contaminated by S. aureus strains, while 19.4% and 13.0% of Japanese-style desserts and human hands respectively were contaminated. Ninety-four isolates of S. aureus were characterized as to their biological properties and enterotoxigenicity. Although staphylococcal enterotoxins (SEs) were detected by enzyme-linked immunosorbent assay in the cultured broth of all S. aureus isolates, the reversed passive latex agglutination method and the polymerase chain reaction showed only 39 (41.5%) and 40 (42.6%) samples respectively as SE-positive. The predominant type of SE was SEB (67.5%), and eight strains produced SEA. None of the S. aureus strains had penicillin-binding protein 2', showing that methicillin-resistant S. aureus was not present in the samples.     

Microbial biocenosis of the nasal mucosa in healthy persons and in Staphylococcus carriers

The normal microflora of the nasal mucosa in man is differentiated into main, complementary and casual microflora, taking into account its isolation rate and characteristics of microbial contamination. The main microflora of adults, in contrast to children, is represented, in addition to coagulaso-negative (CN) staphylococci, by bacteria of the genus Corynebacterium. In staphylococcal carrier state a decrease in the isolation rate and the amount of bacteria belonging to the main and complementary microflora (CN staphylococci, Micrococcus, Streptococcus, Bacillus) was observed. Moreover, in carriers the weakening of the degree of association between CN staphylococci, Micrococcus, Corynebacterium, Streptococcus in symbiotic pairs was noted. In the absence of S. aureus carrier state the main and complementary microflora was characterized by the combination of the factors of antagonism and persistence, while in carrier state the complex of colonization factors was defective in the main microflora and well pronounced in coagulase-positive staphylococcal strains and enterobacteria.     

Heterogeneity in phage sensitivity in populations of S. aureus vegetating in patients and carriers

It was found that the S. aureus populations vegetating in patients and carriers were heterogeneous by phagegroup reference of the strains isolated in 31.1 and 23.9% of cases, respectively, and in 35.9 and 26.9%--phagovars. The frequency and the extent of variability of the populations in the patients depended on the character of the disease, the site of infection and the association of the focus with the external environment, and in carriers--on the localization and the carrier category. S. aureus populations habituating in the patients with the primary purulent processes and mastitis, as in the closed processes and in cases of extrahospital infection consisted, with rare exception, of the strains of one phagovar. In a considerable number of patients with purulent processes after the incision (38.0%), with infected wounds (37.2%), and particularly with burns (78.6%) of the S. aureus population consisted of 2, 3 and even 4 phagovars. Variable were also populations vegetating in patients with open processes (47.1%) and in hospital (26.5%) and mixed infection (52.6%). The phage-type composition of the S. aureus populations in carriers was also characterized by heterogeneity, which was more pronounced in chronic carriers and in case of localization of the processes in the nose. On the basis of the data obtained the minimal number of cultures which should be studied from the microbial focus in order to obtain objective data on the composition of phagovars in the population of various categories of patients and carriers was calculated.     

The role of human innate immune factors in nasal colonization by Staphylococcus aureus

Staphylococcus aureus colonization of the human nares predisposes to sometimes severe auto-infection. To investigate whether genetic polymorphism affects the S. aureus carriage status, sequence variation in alpha-defensin and beta-defensin, and mannose-binding lectin (MBL) genes were determined for a group of volunteers (n=109) with known S. aureus nasal carriage status. DEFA1/3 expression was measured in a subset of the volunteers (n=32). None of the single nucleotide polymorphisms studied could clearly distinguish the (non) carriage groups. S. aureus carriers differed from non-carriers in baseline level of HNP1-3 peptide production (median: 218 versus 89mug/ml, P=0.016). No association between HNP1-3 levels and the individual sequence polymorphisms was documented. The combined copy numbers of DEFA1/A3 genes ranged from 5 to 23 per diploid genome. A linear correlation between combined copy numbers and HNP1-3 peptide concentrations in nasal secretions of non-carriers was noted (r(2)=0.8991). DEFA3 gene was absent in 25% of the individuals. MBL haplotype A was overrepresented in persistent S. aureus carriers (87% vs. 67%; P=0.038). In conclusion, defensin gene polymorphism, both in sequence and in gene copy numbers, does not seem to be involved in S. aureus carriage predisposition. However, MBL haplotypes do so significantly. Baseline HNP1-3 production is more the consequence of S. aureus colonization than a reason for the (non) carrier status.     

Frequency of the isolation of staphylococci from domestic animals and strain identification

Staphylococci occur in donkeys more frequently than in other animals, and only from donkeys coagulase-negative staphylococci, characteristic of humans (S. hominis, S. capitis, S. cohnii), were isolated. Least frequently staphylococcal carrier state was registered in cats; in these animals only coagulase-negative strains were found to occur. From 30 donkeys coagulase-positive staphylococci belonging to 47 S. aureus strains were isolated. These strains differed from known ecological variants in their biological properties, thus suggesting the existence of S. aureus ecovar specific for donkeys. These strains did not coagulate human, bovine and ovine plasma, but coagulated rabbit plasma in 100% of cases and donkey plasma only in 53% of cases; at the same time they relatively often produced delta hemolysin, rarely phosphatase and hyaluronidase and never fibrinolysin. These strains were typed by KPC phages, mainly 116 and 117.     

Immune proteomics of Staphylococcus aureus

Immune proteomics is an increasingly powerful tool for the investigation of the adaptive immune response to natural encounters between micro-organisms and their hosts. The versatile species Staphylococcus aureus serves to illustrate how these techniques can be employed to appreciate the complexity and diversity of the host-pathogen interactions in unprecedented detail and completeness. Such knowledge is important for the development of effective vaccines as well as informative diagnostic and novel therapeutic tools. From high-resolution immune proteome studies, general rules underlying the human adaptive immune response to S. aureus colonization and infection are beginning to emerge against a background of extreme diversity: S. aureus carriers develop immune memory for their colonizing strain, but even non-carriers are frequently exposed to S. aureus, resulting in specific antibodies. During bacterial invasion, immune-competent individuals rapidly mount an antibody response to a large panel of S. aureus antigens. However, every patient starts from a personal baseline antibody profile reflecting his or her history of encounters with S. aureus.     

Biological Evaluation of Carpeting

Studies of microbial contamination were carried out on a carpet strip (acrilan) installed in a laboratory corridor and on two carpet strips (acrilan and wool) installed in two rooms in a pediatric hospital. A sampling procedure of randomly removing 8-mm plugs from the carpets was used for subsequent enumeration and identification of contaminating microorganisms. Microbial counts increased with time, reached a "plateau" at about 4 weeks, and appeared to be related to the amount of activity present in the carpeted area. Vacuuming of carpets showed only a slight reduction in the number of recoverable microorganisms. Qualitative studies on a strip of acrilan carpet installed in a hospital room indicated that Staphylococcus epidermidis and gram-positive nonsporeforming rods were the predominating microorganisms. Coagulase-positive S. aureus organisms were isolated during every sampling period, and gram-negative rods were also regularly isolated. Most nitrate-reducing gram-negative rods belonged to the Enterobacter and Escherichia groups. Survival studies conducted on carpet strips after hospital installation showed relatively constant levels of contamination for about 6 weeks, followed by a gradual reduction in numbers; coagulase-positive S. aureus were found for 35 days, whereas the proportions of most organisms remained relatively constant with time.     

Direct detection of nasal Staphylococcus aureus carriage via helicase-dependent isothermal amplification and chip hybridization

ABSTRACT: BACKGROUND: The bacterium Staphylococcus aureus constitutes one of the most important causes of nosocomial infections. One out of every three individuals naturally carries S. aureus in their anterior nares, and nasal carriage is associated with a significantly higher infection rate in hospital settings. Nasal carriage can be either persistent or intermittent, and it is the persistent carriers who, as a group, are at the highest risk of infection and who have the highest nasal S. aureus cell counts. Prophylactic decolonization of S. aureus from patients' noses is known to reduce the incidence of postsurgical infections, and there is a clear rationale for rapid identification of nasal S. aureus carriers among hospital patients. FINDINGS: A molecular diagnostic assay was developed which is based on helicase-dependent target amplification and amplicon detection by chip hybridization to a chip surface, producing a visible readout. Nasal swabs from 70 subjects were used to compare the molecular assay against culturing on "CHROMagar Staph aureus" agar plates. The overall relative sensitivity was 89%, and the relative specificity was 94%. The sensitivity rose to 100% when excluding low-count subjects (<100 S. aureus colony-forming units per swab). CONCLUSIONS: This molecular assay is much faster than direct culture and has sensitivity that is appropriate for identification of high-count (>100 S. aureus colony-forming units per swab) nasal S. aureus carriers who are at greatest risk for nosocomial infections.     

Effect of the ABO blood group phenotype on the Staphylococcus aureus bacterial carrier state

326 employees of 4 medical institutions (1 regional hospital, 2 city hospitals and a maternity clinic) were examined for the presence of S. aureus carriership. Examinations were made every 3 months for 3 recent years. The results of these examinations were compared with the distribution of the blood groups in the AB0 system among the carriers. Constant and malignant carrier state was detected mainly in persons with blood group A.     

Isolation,structural characterization,and immunological evaluation of a high-molecular-weight exopolysaccharide from Staphylococcus aureus

Colonization of implanted medical devices by coagulase-negative staphylococci such as Staphylococcus epidermidis is mediated by the bacterial polysaccharide intercellular adhesin (PIA), a polymer of beta-(1-->6)-linked glucosamine substituted with N-acetyl and O-succinyl constituents. The icaADBC locus containing the biosynthetic genes for production of PIA has been identified in both S. epidermidis and S. aureus. Whereas it is clear that PIA is a constituent that contributes to the virulence of S. epidermidis, it is less clear what role PIA plays in infection with S. aureus. Recently, identification of a novel polysaccharide antigen from S. aureus termed poly N-succinyl beta-(1-->6)-glucosamine (PNSG) has been reported. This polymer was composed of the same glycan backbone as PIA but was reported to contain a high proportion of N-succinylation rather than acetylation. We have isolated a glucosamine-containing exopolysaccharide from the constitutive over-producing MN8m strain of S. aureus in order to prepare polysaccharide-protein conjugate vaccines. In this report we demonstrate that MN8m produced a high-molecular-weight (>300,000 Da) polymer of beta-(1-->6)-linked glucosamine containing 45-60% N-acetyl, and a small amount of O-succinyl (approx 10% mole ratio to monosaccharide units). By detailed NMR analyses of polysaccharide preparations, we show that the previous identification of N-succinyl was an analytical artifact. The exopolysaccharide we have isolated is active in in vitro hemagglutination assays and is immunogenic in mice when coupled to a protein carrier. We therefore conclude that S. aureus strain MN8m produces a polymer that is chemically and biologically closely related to the PIA produced by S. epidermidis.     

The frequency of the production of toxic-shock exotoxin by Staphylococcus aureus strains isolated in the USSR

515 S. aureus strains, isolated from carriers and patients with staphylococcal infection in different regions of the USSR, were studied. Of these, 52.2% were found capable of producing exotoxin of toxic shock (ETS). The occurrence of the capacity for ETS production was the same among the strains isolated from the upper respiratory ways of carriers and from the purulent inflammatory foci of patients and little varied in staphylococci isolated in different regions. The study revealed that in strains sensitive to the typing phages of the International Set the capacity for ETS production occurred considerably more frequently than in nontyped cultures. No essential differences with respect to this sign between strains belonging to different phage groups were established.     

SPF大鼠感染金黄色葡萄球菌原因的调查分析

目的连续监测某实验动物饲养场SPF大鼠携带的金黄色葡萄球菌Staphylococcus aureus(SA)情况,结合该饲养场环境、人员等检测结果,查找污染源,为保障和提高实验动物质量提供依据。方法2011—2017年依据《实验动物金黄色葡萄球菌检测方法(GB/T 14926.14-2001)》对SPF大鼠进行SA监测,并采集饲养环境和饲养人员的样本进行检测。对所有分离的SA菌株应用金黄色葡萄球菌A蛋白(SPA)基因分型和脉冲场凝胶电泳(PFGE)分型,分析污染源。结果35份SPF大鼠检出16株SA,检出率45.71%;18份饲养环境和饲养人员样本检出2株SA,检出率11.11%。SPA分型可分成5个型别,T2360为优势型别,主要由2013年和2017年SPF大鼠中的菌株组成。PFGE有5种带型,SA4为主要带型。饲养环境中SA的PFGE带型与2017年SPF大鼠中的完全一致。结论饲养环境中存在的SA与SPF大鼠感染的SA具有紧密联系。     

Phage types of Staphylococcus aureus strains and their antibiotic resistance in carriers of medical students population

The phage types of 78 S. aureus strains isolated from nose swabs obtained from a medical students in 2005 -2006 was determined and antibiotic resistance of the phage types was analysed. 680 students were tested in order to obtain the strains and 11.5% of them were carriers of S. aureus. Phage typing was performed using basic set of23 phages and 3 additional phages: 88, 89 and 187. Drug resistance was determined by the disc-diffusion method. The most frequent in studied population were the group III (21.8%) and strains lysed by phages belonging to varied groups (21.8%). Highly different phage patterns were observed among strains belonging to each of the group. Strains belonging to the group III as the strains lysed by phages from varied groups were most frequently resistant only to penicillin (52,9% respectively). Resistance to penicillin was also most often observed in the strains belonging to another groups and phage types. Usefulness of the additional phages 88,89 and 187 was in the investigations as no more than 51% of strains was lysed by this phages.     

Ecological ranging of the Volgograd territory on the basis of Staphylococcus aureus resident carrier state determination

The evaluation of S. aureus resident carrier state on the nasal mucosa among school children showed that its intensity was determined by the ecological factors in the place of residence. Under favorable conditions of the central part of the city the level of S. aureus carrier state was 25.4 +/- 3.1%, while in the northern and southern parts of the city, where most of major metallurgical and chemical plants are situated, these values were 44.4 +/- 4.2% and 45.9 +/- 1.6%. The calculation of the factor of staphylococcal resident carrier state (FSRCS), i.e. the ratio of the carrier state levels in the ecologically favorable (control) zone and in the zone under study, revealed that the FSRCS values in the northern and southern zones were 1.81 and 1.74. Thus the ecological situation could be regarded as critical in none of the districts of Volgograd. The levels of S. aureus resident carrier state were highly correlated to the degree of air pollution, evaluated by the factor of total air pollution, and upper respiratory tract diseases in children. The level of S. aureus resident carrier state may be used as a marker in the ecological ranging of the city territories.     

High phenotypic diversity in infecting but not in colonizing Staphylococcus aureus populations

In hostile environments diversity within a bacterial population may be beneficial for the fitness of the microbial community as a whole. Here we analysed the population diversity of Staphylococcus aureus in infecting and colonizing situations. In the study, performed independently in two German centres, the heterogeneity of the S. aureus population was determined by quantifying the occurrence of phenotypic variants (differences in haemolysis, pigmentation, colony morphology) in primary cultures from nose, oropharyngeal and sputum specimens from cystic fibrosis (CF) patients and in nose swabs from healthy S. aureus carriers. The proportion of heterogeneous samples, the number of clearly distinguishable isolates per sample and the qualitative differences between phenotypes was significantly higher in CF sputum specimens than in the other samples. The heterogeneity of the S. aureus population could be correlated with high bacterial densities in the sputum samples. In patients co-infected with Pseudomonas aeruginosa lower S. aureus bacterial loads and less heterogeneity in the S. aureus population were observed. Typing of all S. aureus isolates from heterogeneous samples by pulsed-field gel electrophoresis or spa typing revealed that the bacteria were polyclonal in 30%, monoclonal with minor genetic alterations in 25% or not distinguishable in 69% of the specimens. Some specimens harboured monoclonal and polyclonal variants simultaneously. Importantly, differences in antibiotic susceptibility were detected in phenotypic S. aureus variants within a single specimen. Diversification of a S. aureus population is highly favoured during chronic CF lung infection, supporting the general hypothesis that maintenance of intrahost diversity can be of adaptive value, increasing the fitness of the bacterial community.     

Staphylococci in the microbiocenosis of the skin of the hands]

The skin autoflora on the pad of a forefinger and the back and palm of a hand was studied in 40 healthy males aged 18-60 years by the modified washing and scraping method of P. Williamson and A. Kligman. 638 cultures of aerobic microorganisms, including coccal (55.3%) and bacilliform (44.7%) microbes, were isolated. In 6 persons (15%) coagulase-positive staphylococci were detected. Out of 10 coagulase negative species of this genus, S. epidermidis, S. saprophyticus and S. warneri occurred most frequently on the skin of hands. The highest density of bacterial populations (10.970 +/- +/- 1.845 cells/sq. cm) was registered on the back of hands, the surface of palms was found to have somewhat lower density (8.679 +/- 1.282 cells/sq. sm) and the skin of forefingers, the lowest density of bacterial populations (6.878 +/- +/- 1.137 cells/sq. sm). 17.5% of examined persons were found to be carriers with S. aureus isolated from their nasal mucosa. S. aureus isolated from the skin surface and the nasal cavity of different persons belonged to different phage variants, but S. aureus isolated from the nasal cavity and the skin of the same person belonged to one phage variant.