Variability of the microfloral makeup of the pathological focus in suppurative infection]

During the period of hospital treatment a change in the composition of would microflora in 145 patients was found to occur, which affected the characteristics of microflora in respect of species, types and strains. This change consisted in the appearance of new (secondary) species, variants and strains and in the disappearance of some original (primary) ones. The populations of staphylococci were found to vary in the level and spectrum of their resistance to antibiotics (resistovars) and in the degree and spectrum of their sensitivity to staphylococcal typing phages (phagovars). Changes in the populations of staphylococci were caused mainly by the cange of S. aureus or by the additional appearance of their new variants which belonged, as a rule, to phage group II, had multiple resistance to antibiotics and corresponded to the phagovars of the hospital flora. The development of hospital variants in open wounds led to an increased general level of resistance of staphylococcal populations to antibiotics.     

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.     

A trial of the use of mupirocin in the nasal carriage of Staphylococcus aureus in medical personnel]

Many hospital-acquired purulent diseases and wound infections are due to multiresistant hospital strains of Staphylococcus aureus. The role of S. aureus nasal carriage in development of wound infections due to autoinfection is confirmed. Not only inpatients but also hospital staff can be highly colonized with coagulase positive staphylococci. The S. aureus persistence in hospital personnel results in distribution of the microorganisms in the environment. Therefore, detection of S. aureus carriers without signs of the infection among the hospital personnel and eradication of the pathogen make it possible to control outbreaks of S. aureus infection in hospitals. Clinical efficacy of nasal ointment of mupirocin in the treatment of S. aureus carriers among the intensive care personnel of the N. N.Blokhin Cancer Research Center was evaluated. S. aureus nasal carriage was diagnosed in 17 (26 per cent) out of 65 persons. All the isolates were susceptible to oxacillin. 5-7 days after discontinuation of the mupirocin nasal ointment use eradication of S. aureus was stated in 100 per cent of the cases. The effect was still observed in 94 per cent of the cases in 1 month, in 76 per cent of the cases in 5-6 months and in 60 per cent of the cases in 8-9 months. It is believed that mupirocin nasal ointment (Bactroban) is convenient to use, low toxic and highly active in the treatment of persons with S. aureus nasal carriage.     

Sources of intrapopulation variability in causative agents of nosocomial infection

The mechanisms of heterogeneity of S. aureus and P. aeruginosa populations of pathological foci in patients with wound, traumatic, and burns infections were studied. It has been established that populations of the mentioned species in the sources of infection (patients and carriers) are pronouncedly heterogeneous and objects in the external environment serving as factors of transmission are contaminated with a whole complex of diverse variants. The conclusion can therefore be drawn that the first source of intrapopulation variability of wound populations of microbes is the presence of varying strains and variants in the infecting dose of the causative agent. The second source consists in repeated superinfection (immigration) of pathological processes by new, usually nosocomial, strains and variants of the same species with their subsequent selection during the patients' stay in the health-service establishment. Other sources of population variability, such as mutation and recombination, are of minor importance. With respect to the obtained results it is necessary to increase the volume of the representative sample of cultures in bacteriological diagnosis of open processes, to protect them reliably from superinfection, to follow up dynamically changes in the composition of causative agents and to provide for suitable correction of chemotherapy.     

Superantigen types inStaphylococcus aureus isolated from patients with cystic fibrosis

The screening of 17 SAg genes of S. aureus isolated from the sputum of cystic fibrosis (CF) patients revealed that among 47 genetically different strains, 39 (83 %) carried SAg genes. Superantigens forming enterotoxin gene cluster were detected in 20 strains. The 2nd most common superantigen type was selk detected in 13 strains. In 9 strains, selk occurred together with the sea gene. Out of 74 strains recovered from nasal carriers, 56 (75 %) were found to carry SAg genes, 38 carried egc genes, while selk was detected in 5 strains. The predominant SAg types in both investigated S. aureus populations were egc and selk/sea, but selk gene frequency was significantly higher in the CF-derived strains.     

Host-microbe interplay in persistent Staphylococcus aureus nasal carriage in HIV patients

It has been shown that persistent Staphylococcus aureus nasal carriage results in increased bacterial dispersal and a higher risk of infection compared to non-or-intermittent S. aureus carriage. Although many studies investigated S. aureus nasal carriage in HIV patients, none compared persistent carriage to non-persistent carriage nor were studies performed in the HAART era. We investigated the host-microbe interplay of persistent S. aureus nasal carriage in HIV-infected patients by studying host determinants of persistent carriage as well as the genetic structure of S. aureus strains isolated. We compared this genetic structure with the previously determined population structure of S. aureus isolates obtained from healthy individuals. Between February 2004 and June 2005 all HIV patients visiting the outpatient department of Erasmus MC (Rotterdam, The Netherlands) were asked to participate in this study. Participants were interviewed and screened for persistent S. aureus carriage using two semi-quantitative nasal swab cultures. For 443 patients two cultures were available, 131 (29.6%) were persistent carriers, which is significantly higher as compared to healthy individuals from the same geographic region (17.6%; P<0.0001). Male sex (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.32-3.73), current smoking (OR, 0.58; 95% CI, 0.38-0.90), Pneumocystis jiroveci pneumonia (PCP) prophylaxis (OR, 0.39; 95% CI, 0.16-0.97) and antiretroviral therapy (OR, 0.61; 95% CI, 0.38-0.98) were independent determinants of persistent carriage. Only two strains were mecA positive (1.2%) and no PVL positive strains were detected. The population structure of S. aureus strains isolated from HIV patients appeared to be strongly overlapping with that of S. aureus isolates from healthy individuals.     

Analysis of plasmid profile of antibiotic-resistant Enterobacteriaceae circulating in hospitals

Certain pheno- and genotype properties of S. typhimurium and some other representatives of Enterobacteriaceae resistant to antimicrobial drugs were studied. The strains were isolated from children with salmonellosis within 4 months when an infection hospital was subjected to microbiological observation. It was shown that by their antibiotic resistance, phagovars and molecular weights of the plasmid DNas, the strains S. typhimurium were similar to those isolated during hospital infections. The conjugative plasmids responsible for antibiotic resistance in some strains did not differ in their molecular weights and antibiotic resistance markers. The strains S. typhimurium similar in their pheno- and genotype properties were isolated only from 2 patients which allowed one to consider it possible that the patients were infected by the strains of common genesis. Analysis of nonpathogenic representatives of Enterobacteriaceae isolated from the patients along with the S. typhimurium strains confirmed the fact that the patients were infected with the same pathogenic strain.     

Changes in the structure and antibiotic sensitivity of the wound microflora in suppurative surgical infection of the soft tissues

The results of the study on the composition, properties and antibiotic sensitivity of pathogenic microbes isolated from purulent wounds of the soft tissues of patients treated in the Institute clinic in 1977-1980 are presented. The frequency of secondary infection of the purulent wounds was estimated. During this period the percentage of gram-negative bacteria isolated from opened purulent foci increased. In some cases investigation of the time course of the purulent processes revealed new microbial strains, such as pathogenic staphylococci or opportunistic gram-negative bacteria. Sometimes replacement of the causative agent by new organisms was observed. The new strains were high- and multiple-resistant to the antibiotics.     

The chemoluminescence of the primary focus of a suppurative infection and of isolated neutrophils exposed to dimephosphon]

The influence of dimephosphone at concentrations of 0.001 M-0.75 M on the chemiluminescence of tissues at the focus of purulent infection in the ear of a guinea pig, on the survival rate of the experimental animals injected with the lethal dose of Staphylococcus aureus, as well as on the spontaneous and stimulated chemiluminescence of blood neutrophils in patients with wound infection, was studied. The study showed that different concentrations of dimephosphone oppositely influenced the intensity of the chemiluminescence of neutrophil suspensions and tissues at the focus of infection: low concentrations were found to produce stimulating action and high concentrations, suppressive action. At the highest concentration used in this study (0.75 M) dimephosphone prevented the death of the animals receiving lethal doses of S. aureus.     

Use of nasal mupirocin for Staphylococcus aureus: effect on nasal carriers and nosocomial infections

Staphylococcus aureus is the agent of community-acquired and nosocomial infections. Twenty to 35% of the population permanently carries it in the nose and oropharynx, and additional 50%, carries it intermittently. Topical calcium mupirocin is an antibacterial agent against Staphylococcus aureus recommended to eradicate nasal and hand colonization in patients and health care workers. The prevalence of nasal S. aureus was determined in patients undergoing cardiovascular surgery. In addition, the effect of mupirocine on the number of carriers and rate of nosocomial infections was evaluated. An experimental prospective study was undertaken with two groups of patients: one treated with mupirocin (n = 96), and the other without treatment (n = 95). Tests for presence of nasal S. aureus and nosocomial infections were conducted in all patients. A 34% prevalence of S. aureus carriers was found. A decrease of the prevalence was found in both treated (87%) and untreated patients (33%), but in significantly different proportions (p = 0.0002, RR = 0.22, 95%CI = 0.09-0.054). This result demonstrated the effectiveness of a mupirocin treatment program to decrease numbers of nasal carriers. With regard to nosocomial infection, S. aureus prevalence was 3.6%, occurring mostly in control patients (6 of 7). Total nosocomial infection prevalence was 17.3%, evenly distributed in treated and untreated patients. This suggested that mupirocin use did not decrease the number of nosocomial infections.     

Effect of plasmids for multiple antibiotic resistance on the change in Salmonella typhimurium phagovar

The data on the influence of acquired plasmid resistance to antibiotics on S. typhimurium phagovar. Plasmid R was transferred from S. typhimurium strain, isolated from the focus of hospital salmonellosis and resistant to the lytic action of phages, to Escherichia coli K12 and then to antibiotic-sensitive S. typhimurium strains of different phagovars, isolated from patients with alimentary toxicoinfections. The influence of plasmid R on the phagovar of recipient strains, most pronounced in strains of phagovar I, was revealed. The transconjugates of this phagovar considerably changed sensitivity to phages and in some cases acquired resistance to the lytic action of typing phages, thus becoming identical in this feature to the donor of the plasmid.     

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.     

The microbial factor in the chemiluminescence of the peripheral blood neutrophils of patients with suppurative surgical infection

The luminol-dependent chemiluminescence of neutrophils in the peripheral blood of 30 healthy adults and 39 patients with the local and generalized forms of purulent infection was studied. Nonstimulated chemiluminescence and the index of chemiluminescence stimulation in the presence of opsonized Staphylococcus aureus added in vitro were determined. The former characteristic was found to be directly and the latter one, inversely related to the concentration of S. aureus, Escherichia coli and Candida albicans, but not E. epidermidis, Pseudomonas aeruginosa or Citrobacter, in the primary focus. At the microbial concentration exceeding 10(4) cells/g of tissue, the former characteristic was essentially higher than the level of chemiluminescence in healthy persons. With the improvement of the general state of the patients and in the absence of microorganisms in the wound as the result of complex treatment this characteristic decreased to values comparable with the reaction of neutrophils in healthy persons.     

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.     

Population studies of methicillin-resistant and -sensitive Staphylococcus aureus strains reveal a lack of variability in the agrD gene, encoding a staphylococcal autoinducer peptide

The virulence of Staphylococcus aureus is controlled by the accessory gene regulator (agr) system, including an extracellular inducer encoded by agrD. Variable agr PCR restriction fragment length polymorphism (RFLP) patterns of unique S. aureus strains (n = 192) were determined for a region comprising agrD and parts of the neighboring agrC and agrB genes. Twelve unique RFLP patterns were identified among S. aureus strains in general; these patterns were further specified by sequencing. All sequences could be catalogued in the three current agr groups. A major proportion of the S. aureus strains belong to agr group 1, whereas only 6% of the methicillin-susceptible S. aureus strains and 5% of the methicillin-resistant S. aureus strains belong to agr groups 2 and 3, respectively. The homology between groups varied from 75 to 80%, and within groups it varied from 96 to 100%. Different levels of sequence variability were observed in the different agr genes. agr-related bacterial interference among colonizing S. aureus strains in the noses of persistent and intermittent human carriers was studied. S. aureus strains belonging to different agr groups were encountered in the same individual. This may suggest that the activity of the agrD gene product does not define colonization dynamics, which is further substantiated by the rarity of agr group 2 and 3 strains.     

Nasal carriage of methicillin-resistant Staphylococcus aureus among smokers and cigarette factory workers

Effects of smoking and tobacco on nasal carriage and colonisation rates of Staphylococcus aureus were investigated on 368 healthy males aged between 30 and 40 years old. The study group comprised 100 non-smokers (control group), 91 smokers, and 177 cigarette factory workers (42 smokers, 135 non-smokers). Quantitative cultures were done from the nasal swabs of all participants. After identification and determination of colony counts, S. aureus strains were tested for methicillin resistance using the oxacillin disk diffusion method. The rates of nasal carriage of S. aureus were found to be 30% in the control group, 33% in smokers, and 41% in cigarette factory workers. Overall, S. aureus colonisation (> or = 500 cfu/ml) was detected in 72% of the carriers (55/76). Colonisation rates were 43%, 63%, and 85% in the carriers of the study groups, respectively. An increasing colonisation rate was detected in accordance with the increasing number of cigarettes smoked per day, and smoking period. While methicillin-resistant Staphylococcus aureus was only found in 3% of the 30 S. aureus strains isolated from the control group, its isolation rate was 20% in the 30 S. aureus isolates of the smokers, and 33% in the 72 S. aureus isolates of the cigarette factory workers. These results indicate that cigarette and/or tobacco appear to have noticeable effects on the ecology of the nose.     

糖尿病足感染的细菌学调查及耐药性分析

目的 了解临床糖尿病足患者感染的细菌分布及耐药性分析.方法 2009年至2010年,共调查135例糖尿病足患者.结果 检出细菌株数为107株,其中革兰阳性菌44株,占41.1％;革兰阴性菌57株,占53.3％;真菌6株,占5.6％.需氧菌感染80例,检出率59.3％.以金葡菌、链球菌、变形杆菌和大肠埃希菌为主要感染菌.金黄色葡萄球菌的耐药率明显低于其他葡萄球菌.大肠埃希菌治疗以亚胺培南首选,也可选用β-内酰胺类加酶抑制剂.结论 检出革兰阴性菌57株,革兰阳性菌44株,应根据药敏情况合理应用抗菌素.     

Antagonism between hospital strains of Staphylococcus aureus and lactic acid bacteria in vitro and the use of the latter as a sanitary agent

The study of antagonism between S. aureus hospital strains and lactic acid bacteria, strain 317/402 "Nariné", revealed that the latter possessed high antagonistic activity. A new method for the sanitation of carriers of S. aureus hospital strains was developed; this method made it possible to limit the epidemiological significance of 82% of these strains.     

Distinctive patterns in the human antibody response to Staphylococcus aureus bacteremia in carriers and non-carriers

Staphylococcus aureus is both a prominent cause of nosocomial infections with significant morbidity and mortality and a commensal with nasal carriage in around 30% of the population. The rapid spread of multi-resistant strains necessitates novel therapeutic strategies, a challenging task because the species S. aureus and the host response against it are highly variable. In a prospective study among 2023 surgical and non-surgical patients, 12 patients developed S. aureus bacteremia. They were analysed in detail using a personalized approach. For each patient, the extracellular proteins of the infecting S. aureus strain were identified and the developing antibody response was assessed on 2-D immunoblots. S. aureus carriers showed clear evidence of strain-specific pre-immunization. In all immune-competent bacteremia patients, antibody binding increased strongly, in most cases already at diagnosis. In endogenous infections, the pattern of antibody binding was similar to the pre-infection pattern. In exogenous infections, in contrast, the pre-infection pattern was radically altered with the acquisition of new specificities. These were characteristic for individual patients. Nevertheless, a common signature of 11 conserved S. aureus proteins, recognized in at least half of the bacteremic patients, was identified. All patients mounted a dynamic antibody response to a subset of these proteins.