Normal Skin Flora Research Articles

Aeromonas Sobria: a Rare Cause of Continuous Ambulatory Peritoneal Dialysis-Related Peritonitis

Peritonitis is a very common complication in patients treated with continuous ambulatory peritoneal dialysis. The most common causes are gram positive cocci (part of the normal skin flora), and then gram negative bacteria, while fungi are listed as a rare cause of peritonitis. Aeromonas species are identified as a rare cause of continuous ambulatory peritoneal dialysis-related peritonitis. Among them, Aeromonas hydrophila is somewhat more common, followed by Aeromonas caviae.Case presentation. We reported a case of continuous ambulatory peritoneal dialysis peritonitis caused by Aeromonas sobria that is extremely rare cause of this type of peritonitis. In our patient, pseudomembranous colitis occured as a complication and, reinfection – another episode of peritonitis with Klebsiella pneumoniae. Treatment with third-episode cephalosporins was successful and patient continued treatment with continuous ambulatory peritoneal dialysis. Conclusions. The rare causes of peritonitis should not be ignored, especially those which lead to increased morbidity and mortality of patients.

Infectious Loss of Tissue Expanders in Breast Reconstruction: Are We Treating the Right Organisms?

Postoperative infections following tissue expander-based breast reconstruction represent a significant threat to the reconstructive process. Studies have found the incidence to be as high as 29%. There has been abundant research into the risk factors associated with these infections, although very few studies have focused on the causative organisms. The purpose of this study was to investigate the bacterial flora associated with tissue expander infections after breast reconstruction. A retrospective analysis of all patients who underwent tissue expander-based breast reconstruction at our institution between February 2010 and April 2013 was conducted. The medical records were reviewed for demographic information, medical history, operative technique, postoperative course, and culture results. Descriptive data analysis was then performed. A total of 56 tissue expander infections were identified in 49 patients during the study period. 41.1% of the cultures grew gram-positive organisms, whereas 28.6% grew gram-negative species. The 2 most common organisms were Staphylococcus aureus (17.9%) and Staphylococcus epidermidis (14.3%). Pseudomonas aeruginosa was the most frequent gram-negative species and was also the third most frequent organism cultured (10.9%). Due to the high rate of infection in breast reconstruction patients, adequate perioperative prophylaxis is necessary. The surgeon must also be prepared to treat patients who may return with infection postoperatively. Although the majority of our infections were secondary to normal skin flora, a significant proportion were caused by gram-negative species. Given these results, the empiric antibiotic of choice for postoperative infections should be reconsidered to cover for these various organisms.

由孔氏创伤球菌引起糖尿病性足病感染的个案报道

背景：孔氏创伤球菌是兼性厌氧菌，最初被认为是一种人体下肢皮肤的正常菌群，因孔氏创伤球菌引起侵袭性感染的病例在国内外文献报道中极其罕见，现报道我院中医外科一例由此菌引起的糖尿病足的病历。病例：患者为67岁女性以糖尿病足收入我院中医外科，术中和术后取分泌物做细菌培养，两次结果均培养出孔氏创伤球菌，后经左氧氟沙星静脉滴注和我院自制中药联合用药后，病情明显好转后出院。讨论：本文报道的病例在国内是第一例由孔氏创伤球菌引起的糖尿病性足病感染的病例，现在随着大量抗生素的使用，原认为是人体正常菌群的孔氏创伤球菌，也会引起人体侵袭性感染，应引起广大临床工作者的高度重视。 Background: Helcococcus kunzii is a facultative anaerobic bacteria, which was originally consi-dered a normal flora of human lower limb skin. The cases of invasive infection caused by Helco-coccus kunzii are extremely rare in domestic and foreign literature. In this paper, the patient with diabetes mellitus caused by Helcococcus kunzii is reported. The patient was 67 year old female with diabetes foot in our hospital surgery. In and after operation, the secretions were taken for bacterial culture. Helcococcus kunzii has been cultured two times. After the intravenous drip of levofloxacin and the combination of Chinese herbal medicine in our hospital, the condition of the patient improved significantly and discharged. Discussion: What has reported in this article is the first case of invasive trauma caused by the pathogen of diabetic foot disease cases in the country. Now with the use of a large number of antibiotics, Helcococcus kunzii, which was originally considered the normal bacteria of body can also cause the body invasive infection. And clinical workers should attach great importance to Helcococcus kunzii.

Cornyebacterium striatum : an Emerging Bug

The increasing prevalence of chronic infections, with frequent exposure to broad-spectrum antibiotics for repeated and prolonged hospitalizations, favors the emergence of nosocomial infection by Gram-positive bacteria, such as outbreaks of Corynebacterium striatum. Cornyebacteria are gram-positive non spore forming rods. Many species are part of the normal skin and mucosal flora of humans. The clinical significance of C. striatum has recently been established. C. striatum has recently been reported to cause a variety of infections including pneumonia, endocarditis, septic arthritis, cerebrospinal fluid infection, surgical site infections and septicemia. In this study, describing three cases of Corynebacterium striatum that are attributed to health care associated infections and presented as post-surgical wound infection and hospital acquired pneumonia. The three cases include a case of a 68 years old lady who was readmitted with fever, pain and purulent discharge from surgical wound of the lower back, a 57 years old man who was readmitted 2 months after a road traffic accident with surgical wound infection of forearm and a 25 years old man on respiratory support after a head injury with ventilator associated pneumonia.

Molecular and Phenotypic Identification and Speciation of Malassezia Yeasts Isolated from Egyptian Patients with Pityriasis Versicolor.

Pityriasis Versicolor (PV) is a common health problem caused by genus Malassezia, a lipophilic fungi found as a part of the normal flora of skin. Although PV is common in Egypt, there is little information regarding the Malassezia species distribution in PV patients to date. To spot a light on the distribution and clinico-epidemiological features of the Malassezia species in PV patients and healthy individuals that were established by conventional phenotypic and molecular techniques. A cross-sectional study including 167 individuals; 137 clinically suspected PV patients attending Mansoura University Hospitals, Egypt and 30 healthy control individuals, was carried out. Characterization of Malassezia species was performed phenotypically by conventional, culture-based methods and biochemical tests. Genomic DNA was extracted from isolated colonies for PCR amplification of the highly conserved 26S rDNA region with further species level identification by Restriction Fragment Length Polymorphism (RFLP) using Hha1 and BstC1 enzymes. The association of Malassezia species with epidemiological profile and clinical characteristics was studied. A 94.2% of PV samples and 13.3% of control samples were positive by Potassium Hydroxide (KOH) while 71.5% of PV samples and 16.7% of control samples yielded growth in culture with high statistically significant differences (p=0.0001, for both methods). By phenotypic methods, only 75.5% of isolates from patients were identified as: M. furfur (51.4%), M. globosa, (29.7%), M. restricta (13.5%) and M. pachydermatis (5.4%) while by RFLP technique, six species were revealed: M. furfur (44.9%), M. globosa (24.5%), M. sympodialis (12.2 %), M. restricta (10.2%), M. obtusa (4.1%) and M. pachydermatis (4.1%). Most species were isolated from hypopigmented lesions of PV patients aged between 20-29 years. Neck and back were the most common affected sites. Only M. furfur (10%) and M. globosa (6.7%) were identified in healthy controls. M. furfur and M. globosa are the commonly encountered species in both healthy and diseased human skin although other species were identified in PV patients. PCR-RFLP method represents a considerably accurate technique in identification of different Malassezia species for better understanding of their effect on the clinico-epidemiological characterization of PV patients in Egypt.

Ketoconazole inhibits Malassezia furfur morphogenesis in vitro under filamentation optimized conditions.

Malassezia furfur, a constituent of the normal human skin flora, is an etiological agent of pityriasis versicolor, which represents one of the most common human skin diseases. Under certain conditions, both exogenous and endogenous, the fungus can transition from a yeast form to a pathogenic mycelial form. To develop a standardized medium for reproducible production of the mycelial form of M. furfur to develop and optimize susceptibility testing for this pathogen, we examined and characterized variables, including kojic acid and glycine concentration, agar percentage, and pH, to generate a chemically defined minimal medium on which specific inoculums of M. furfur generated the most robust filamentation. Next, we examined the capacity of ketoconazole to inhibit the formation of M. furfur mycelial form. Both low and high, 0.01, 0.05 and 0.1µg/ml concentrations of ketoconazole significantly inhibited filamentation at 11.9, 54.5 and 86.7%, respectively. Although ketoconazole can have a direct antifungal effect on both M. furfur yeast and mycelial cells, ketoconazole also has a dramatic impact on suppressing morphogenesis. Since mycelia typified the pathogenic form of Malassezia infection, the capacity of ketoconazole to block morphogenesis may represent an additional important effect of the antifungal.

Incontinence-associated dermatitis: reducing adverse events.

Incontinence-associated dermatitis (IAD) is a common problem in patients with faecal and/or urinary incontinence. Urine alters the normal skin flora and increases permeability of the stratum corneum and faecal enzymes on the skin contribute to skin damage. Faecal bacteria can then penetrate the skin, increasing the risk of secondary infection. However, IAD can be prevented and healed with timely and appropriate skin cleansing and skin protection. This includes appropriate use of containment devices. This article also looks at HARTMANN incontinence pads that have been developed to absorb the fluids that cause IAD and maintain the skin's acidic pH. The acidic pH of the skin contributes to its barrier function and defence against infection. Therefore, maintaining an acidic pH will help protect the skin from damage.

An in vitro investigation into the efficacies of chlorhexidine gluconate, povidone iodine and green tea (Camellia sinensis) to prevent surgical site infection in animals

Background: Surgical site infections are common in veterinary practice; their prevention is based on the preoperative use of topical antimicrobials at the surgical site to reduce resident bacteria to sub-pathogenic levels. Aim Chlorhexidine gluconate (CHG) and povidone iodine (PI) are the most popular options for preoperative skin preparation in veterinary practice, however increasing bacterial resistance to CHG and PI have been reported; therefore investigation into alternative antimicrobials such as Camellia sinensis (green tea: GT) is required. Method The Kirby-Bauer disk diffusion method was used to test the antibacterial activity of four dilutions of CHG, PI and GT on the normal flora of animal skin, represented by S. aureus, S. intermedius, S. uberis and S. pyogenes. Zones of inhibition (ZOI) were measured to assess antimicrobial action. Kruskal-Wallis analyses with Mann-Whitney post-hoc tests determined differences in efficacy between the dilutions of antimicrobials for each bacterium tested. Results All antimicrobials inhibited bacterial growth, CHG was more efficacious than PI and GT (p<0.0001; mean CHG: 24.02± 2.05 mm; mean PI: 4.46±1.35 mm; mean GT: 2.90mm±2.60mm). Although GT produced smaller ZOIs than PI, no significant differences in efficacy existed (p>0.05). Conclusion The results suggest that CHG is the best antimicrobial for preoperative skin preparation. GT did produce an antibacterial effect on three of the four bacteria, although this was inferior to the existing veterinary products used. Therefore GT in the formulation tested is not recommended for use as a veterinary antimicrobial.

Emerging Bacterial Infection: Identification and Clinical Significance of Kocuria Species.

Recently there have been reports of gram-positive cocci which are morphologically similar to both Staphylococci and the Micrococci. These bacteria have been identified as Kocuria species with the help of automated identification system and other molecular methods including 16S rRNA (ribosomal ribonucleic acid) evaluation. Kocuria belongs to the family Micrococcaceae which also includes Staphylococcus species and Micrococcus species. Isolation and clinical significance of these bacteria from human specimens warrant great caution as it does not necessarily confirm infection due to their ubiquitous presence, and as a normal flora of skin and mucous membranes in human and animals. Most clinical microbiology laboratories ignore such bacteria as laboratory and specimen contaminants. With increasing reports of infections associated with these bacteria, it is now important for clinical microbiologists to identify and enumerate the virulence and antibiotic susceptibility patterns of such bacteria and assist clinicians in improving the patient care and management. We review the occurrence and clinical significance of Kocuria species.

Bacteriological study of coagulase positive staphylococci from urine in some akoko communities, ondo state, nigeria

Staphylococci which can be normal skin flora as well as aetiologic agent was examined for their clinical implications from urine sources during the study. The occurrence of staphylococcal species in urine sources of some people in Akoko communities between age group 5 to 55 years was determined. 50 sample sources were screened for this purpose. The total viable bacterial count of urine sample sources range from 0, 1 x 103 cfu/ml and 4 x 103 cfu/ml from Ikun-Akoko, Supare community, Iwaro-Akoko as well as Akungba-Akoko respectively to high microbial load of 50 x 106 cfu/ml from Supare-Akoko. The bacterial isolates were identified using standard microbiological techniques including biochemical characteristics in which 23 (46%) were coagulase positive and 25 (50%) were coagulase negative and 2 (4%) show no growth on Mannitol Salt Agar. The 48 isolates obtained for this study were all Gram positive cocci (Bacteria). The Staphylococcal species obtained were grouped as C.P.S a 1:- Coagulase positive Staphylococcus aureus group 1, C.P.S.a 2:- Coagulase positive Staphylococcus aureus group 2, C.NS 1; Coagulase negative Staphylococcus group 1, C.N.S 2: Coagulase negative Staphylococcus group 2 and C.N.S 3: Coagulase negative Staphylococcus group 3. Some of the isolates tested show multiple antibiotic resistance which is significant clinically in case of treatment of infections in immunocompromised persons. The physico-chemical properties of urine samples collected from the Akoko communities studied was determined using Combi 9 strip/kit. This study will help to generate a database for health management purposes with the aim of controlling Staphylococcus infections. Â

Antimicrobials therapy of anaerobic infections

Anaerobes predominant in the normal human skin and mucous membranes bacterial flora are often a cause of endogenous infections. Anaerobic bacteria are difficult to isolate from infectious sites, and are often overlooked. Anaerobic infections caused by anaerobes can occur in all body sites, including the central nervous system (CNS), oral cavity, head and neck, chest, abdomen, pelvis, skin and soft tissues. The treatment of these infections is complicated by the slow growth of these organisms, their polymicrobial nature and the growing resistance of anaerobes to antimicrobials agents. Antimicrobials are frequently the only form of therapy needed, but in others, they are an important adjunct to surgical drainage and correction of pathology. Because anaerobes are often recovered with aerobic and facultative bacteria, the chosen antimicrobials should cover all pathogens. The antimicrobials effective against anaerobic organisms are metronidazole, carbapenems, combinations of a beta-lactam and a beta-lactamase inhibitor, chloramphenicol, tigecycline and clindamycin.

Cardiovascular Implantable Electronic Device Infections due to Propionibacterium Species.

Propionibacterium species are part of the normal skin flora and often considered contaminants when identified in cultures. However, they can cause life-threatening infections, including prosthetic cardiovascular device infections. Clinical presentation and management of cardiovascular implantable electronic device (CIED) infection due to Propionibacterium species has not been well described. Retrospective review of all cases of CIED infection due to Propionibacterium species admitted to Mayo Clinic between January 1, 1990 and December 31, 2014. Patient charts were reviewed for clinical, microbiological, and imaging data. Descriptive analysis was performed. We identified 14 patients with CIED infection due to Propionibacterium species, accounting for 2.3% of all CIED infections. Patients were predominantly male (n = 12, 86%). The median age at admission was 58.5 years (range 22-83). Twelve patients had implantable cardioverter defibrillators (ICDs) and two had permanent pacemaker systems. Twelve patients had generator pocket infection (86%). Two patients met clinical criteria for CIED-related infective endocarditis. Median time between last device manipulation and infection was 9 months (range 1-98). All patients were treated with complete device removal and antibiotic therapy. Six-month follow-up data were available for 10 patients (71%), with no relapses documented. CIED infections due to Propionibacterium species accounted for 2.3% of all device infections over a 25-year period. The most common infectious syndrome was generator pocket infection with delayed onset. There was an unanticipated predominance of ICDs in this cohort. Cure was achieved in all cases with complete device removal and antibiotic therapy.

The Autoclaving of Autologous Bone is a Risk Factor for Surgical Site Infection After Cranioplasty

This retrospective study was designed to evaluate the effectiveness of autoclaving for the prevention of surgical site infection (SSI) after cranioplasty. Patients who underwent cranioplasty with autologous bone were enrolled. SSI was defined as an infection requiring bone flap removal. Risk factors of SSI, as reported by other researchers, and microbiologic features of SSI were analyzed. All bone flaps were preserved in a deep freezer (-70°C). Autoclaving of the preserved autologous bone flap before cranioplasty was performed for 5 minutes at 135°C in the 26 patients. Eighty patients were enrolled. The mean age was 53.3 years and the male/female ratio was 3:2. Causes of craniectomy included trauma (n= 37) and nontrauma (n= 43). The mean time interval between craniectomy and cranioplasty was 49.7 days. The SSI rate after cranioplasty with autologous bone was 17.5% (n= 14). In univariate analysis, the cranioplasty operation time (P= 0.09) and the use of autoclaved bone (P= 0.00) were supposed to be risk factors for SSI. The use of autoclaved autologous bone was found to be the only risk factor of SSI (P= 0.01; hazard ratio= 8.88) in binary logistic regression analysis. Non-methicillin-resistant Staphylococcus aureus (MRSA) causes were more frequent in the autoclaved group (MRSA, 30%; non-MRSA, 70%) compared with the nonautoclaved group (MRSA, 100%) (P= 0.07). A microscopic examination showed that autoclaving after long-term cryopreservation may result in a loss of bone viability. Autoclaving of autologous bone causes SSI after cranioplasty and it seems to increase the risk of non-MRSA infection by normal skin flora.

Phenotypic and Molecular Antibiotic Resistance Determination of Airborne Coagulase Negative Staphylococcus spp. Strains from Healthcare Facilities in Southern Poland.

This study assessed the antimicrobial resistance of airborne Staphylococcus spp. strains isolated from healthcare facilities in southern Poland. A total of 55 isolates, belonging to 10 coagulase-negative staphylococci (CoNS) species, isolated from 10 healthcare facilities (including hospitals and outpatient units) were included in the analysis. The most frequently identified species were Staphylococcus saprophyticus and Staphylococcus warneri, which belong to normal human skin flora, but can also be the cause of common and even severe nosocomial infections. Disk diffusion tests showed that the bacterial strains were most frequently resistant to erythromycin and tetracycline and only 18% of strains were susceptible to all tested antimicrobials. Polymerase chain reaction amplification of specific gene regions was used to determine the presence of the Macrolide-Lincosamide-Streptogramin resistance mechanisms in CoNS. The molecular analysis, conducted using specific primer pairs, identified the msrA1 gene, encoding active efflux pumps in bacterial cells, as the most frequent resistance gene. As many as seven antibiotic resistance genes were found in one isolate, whereas the most common number of resistance genes per isolate was five (n = 17). It may be concluded that drug resistance was widely spread among the tested strains, but the resulting antimicrobial resistance profile indicates that in the case of infection, the use of antibiotics from the basic antibiogram group will be effective in therapy. However, before administering treatment, determination of the specific antimicrobial resistance should be conducted, particularly in the case of hospitalized patients.

Canine Staphylococcus pseudintermedius sinonasal infection in human hosts

Staphylococcus pseudintermedius is a gram-positive bacterium commonly found as part of the normal skin and nasal flora of healthy dogs. It may act as an opportunistic pathogen in dogs, but has also been shown to colonize the nasal mucosa of humans. We report 4 cases of chronic rhinosinusitis (CRS) refractory to aggressive medical management with cultures that grew S. pseudintermedius, with clinical improvement only after initiating culture-directed therapy. Retrospective review of 4 patients with CRS treated at a tertiary academic medical center with sinonasal cultures growing S. pseudintermedius. All 4 patients are dog owners and had clinical diagnoses of CRS. Three of the 4 patients had a diagnosis related to immune dysfunction (sarcoidosis, Crohn's disease, history of lymphoma). After undergoing endoscopic sinus surgery, each patient was treated with aggressive medical therapy but continued to have purulent nasal discharge. Sinonasal cultures repeatedly grew S. pseudintermedius in all cases, with 3 patients' dogs also having had concurrent S. pseudintermedius wound infections of the ear and leg with similar antibiotic susceptibilities. Treatment with culture-directed therapy improved the infections in all cases. Opportunistic pathogens have a propensity to exacerbate infection in CRS patients with immune dysfunction. We report the first case series of sinonasal S. pseudintermedius infection in humans. Though a rare cause of disease, pathogens such as S. pseudintermedius from nonhuman hosts should be considered in the management of CRS patients refractory to medical therapy.

Staphylococcus aureus and Staphylococcus epidermidis Virulence Strains as Causative Agents of Persistent Infections in Breast Implants.

Staphylococcus epidermidis and Staphylococcus aureus are currently considered two of the most important pathogens in nosocomial infections associated with catheters and other medical implants and are also the main contaminants of medical instruments. However because these species of Staphylococcus are part of the normal bacterial flora of human skin and mucosal surfaces, it is difficult to discern when a microbial isolate is the cause of infection or is detected on samples as a consequence of contamination. Rapid identification of invasive strains of Staphylococcus infections is crucial for correctly diagnosing and treating infections. The aim of the present study was to identify specific genes to distinguish between invasive and contaminating S. epidermidis and S. aureus strains isolated on medical devices; the majority of our samples were collected from breast prostheses. As a first step, we compared the adhesion ability of these samples with their efficacy in forming biofilms; second, we explored whether it is possible to determine if isolated pathogens were more virulent compared with international controls. In addition, this work may provide additional information on these pathogens, which are traditionally considered harmful bacteria in humans, and may increase our knowledge of virulence factors for these types of infections.

Virale oncogenese van het merkelcelcarcinoom

A merkel cell carcinoma (MCC) is a rare, but aggressive neuro-endocrine cutaneous cancer often appearing as a single, painless, skin-colored to red-blue lump on sun-exposed skin. The lesion appears clinically not malignant, but grows rapidly. An MCC is caused by the merkel cell polyomavirus (MCV), a virus that is part of the normal skin flora and that was discovered in 2008. The exposure to ultraviolet radiation and immunosuppression increase the risk of an MCC and provide a suitable environment for the integrated MCV to lead to malignant transformation. Surgery with wide safety margins for localized lesions can be curative. In advanced stages, an MCC is one of the most lethal skin cancers. The scientific knowledge on the MCV is growing with respect to viral integration, carcinogenesis and immune response. The emerging use of this knowledge for clinical practice is discussed.

INVESTIGATION OF BIOFILM FORMATION IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM PLATELET CONCENTRATE BAGS.

Platelet Concentrates (PCs) are the blood components with the highest rate of bacterial contamination, and coagulase-negative staphylococci (CoNS) are the most frequently isolated contaminants. This study investigated the biofilm formation of 16 contaminated units out of 691 PCs tested by phenotypic and genotypic methods. Adhesion in Borosilicate Tube (ABT) and Congo Red Agar (CRA) tests were used to assess the presence of biofilm. The presence of icaADC genes was assessed by means of the Polymerase Chain Reaction (PCR) technique. With Vitek(r)2, Staphylococcus haemolyticus was considered the most prevalent CoNS (31.25%). The CRA characterized 43.8% as probable biofilm producers, and for the ABT test, 37.5%. The icaADC genes were identified in seven samples by the PCR. The ABT technique showed 85.7% sensitivity and 100% specificity when compared to the reference method (PCR), and presented strong agreement (k = 0.8). This study shows that species identified as PCs contaminants are considered inhabitants of the normal skin flora and they might become important pathogens. The results also lead to the recommendation of ABT use in laboratory routine for detecting biofilm in CoNS contaminants of PCs.

A rare clinical manifestation of spinulate demodicosis

Demodicosis is a chronic skin disease caused by Demodex mites such as Demodex folliculorum and Demodex brevis. Demodex mites live in pilosebaceous units and they are regarded as a part of the normal skin flora. Nevertheless, it has been suggested that the presence of five or more mites per cm² by the standardized skin surface biopsy technique could be considered as pathogenic.

Analysis of nosocomial Staphylococcus haemolyticus by MLST and MALDI-TOF mass spectrometry

Coagulase-negative staphylococci (CoNS) are a major component of normal human skin and mucosae flora. However, some species of CoNS can lead to infections in immunocompromised patients and premature newborns. The choice of a rapid and reliable typing method is one of the major problems in the epidemiological monitoring of CoNS, especially Staphylococcushaemolyticus isolates. In this study, we have tested 71 isolates of S. haemolyticus obtained from newborns using the multilocus sequence typing (MLST) and the direct bacterial MALDI-TOF mass spectrometry profiling approaches. To date, there is no standard MLST scheme for investigating the diversity of S. haemolyticus strains. The novel variant of MLST scheme including the tpiA, pta, sh1200, rphE, tphK, mvaK1, and arc loki was tested. The discriminatory power was estimated by the Hunter–Gaston discriminatory index (D) as 0.95. The Composition Correlation Index Matrix (CCI matrix) was calculated to typing the isolates through the analysis of mass spectra; also, the values of the correlation index for different groups of isolates were evaluated. Closely related isolates obtained from the same hospital are characterized by increased values of correlation indices in comparison with these values of isolates collected from various hospitals. The data obtained by both methods allow to describe a clonal structure of S. haemolyticus population and to designate the presence of endemic clones of S. haemolyticus.