Evaluation of the usefulness of selected commercial systems for identification of Streptococcus species

The usefulness was assessed of three commercially available systems for rapid identification of streptococcal strains. The studied material comprised 68 strains of streptococci and enterococci (including 24 standard strains) belonging to serological groups: A (14 strains), B (10), C (11), D (10), F (3) and G (10), as well as 10 S. pneumoniae strains. The strains were isolated from throat, nasal, wound swabs, blood, pus of inpatients and throat and nasal swabs of outpatients. For the identification of streptococci 3 commercially available systems were used: API 20 STREP (bioMerieux, France), rapid ID 32 Strep (bioMerieux, France), Streptoplast PPL 18 (HTL, Poland). The determinations were done according to producer's instructions. The highest percent of correctly identified strains was obtained with the rapid ID 32 Strep--80.9%, with the API 20 STREP--76.4% strains were identified correctly and with the PPL 18--61.8%. The study showed that the API 20 STREP and rapid ID 32 STREP are suitable for the identification of streptococcal strains from groups: A, B, C, D, F and enterococci--group D. The proportions of correctly identified strains from these groups with the Streptoplast PPL 18 were lower than those determined with the bioMerieux systems. Using of three identification systems streptococci from group G and S. pneumoniae strains cannot be identified.     

Carbohydrate assimilation by clinical and environmental Rhodotorula glutinis strains

This study was carried to determine the carbohydrate assimilation patterns of Rhodotorula strains isolated from clinical and environmental specimens. We have tested the commercial system ID 32C (bioMerieux, France) on 80 different strains of Rhodotorula glutinis: 47 strains from clinical samples and 33 strains from environmental samples. The assimilation percentages obtained in our study for galactose, cellobiose, gluconate and sorbose were lower than those showed in the identification table of the method. However, the assimilation percentages for mannitol and esculin were higher. According to our results, we conclude that the numerical profiles and the identification software of the commercial system present limitations for the characterization of some R. glutinis strains.     

Evaluation of Chromalbicans Agar for presumptive identification of Candida albicans

The utility of Chromalbicans Agar (Biolife Italiana, Milano, Italy) was evaluated with 723 clinical isolates and type culture collection strains from different genera including Candida, Cryptococcus, Pichia, Rhodotorula, Saccharomyces, Trichosporon y Zygosaccharomyces. Presumptive identification was confirmed by germ tube test and carbohydrate assimilation on API-ATB ID 32C (bioMerieux, France). Growth on Chromalbicans Agar was very useful for the presumptive identification of C. albicans isolates, and sensitivity and specificity values were significantly high (>97%), since a very low number of isolates were found to be false negative or false positive.     

Etiologic agents of fungemia in hospitalized patients]

The aim of performed examinations was the analysis of fungi as etiological agents of blood infections in patients hospitalized in surgical wards, internal medicine wards and intensive care units of the Medical Academy Central Clinical Hospital in Warsaw. Blood samples from patients hospitalized in 1997 were examined. Peripheral blood samples were incubated in BacT/Alert system (Organon Teknika, USA). Positive blood samples were inoculated on Sabouraud medium with chloramphenicol (bioMerieux, France or Oxoid, England). The time of cultivation was from 48 hours to 7 days at 30 degrees C. Fungal strains were identified by standard mycological procedures with the use of chromogenic medium BBL CHROMagar Candida (Becton Dickinson, USA) and biochemical test ID 32 C (bioMerieux, France). Susceptibility of strains to antifungal agents was determined by ATB FUNGUS method (bioMerieux, France). The total number of positive blood cultures in 1997 was 1380. Forty-two fungal strains were isolated from blood samples (3%). Strains belonged to the following species: C. albicans (17 isolates), C. parapsilosis (15), C. glabrata (3), melibiosica (2), C. pelliculosa (2), C. guilliermondii (1), C. tropicalis (1) and T. beigelii (1). Among fungi cultured from patients hospitalized in operative wards dominated C. parapsilosis (11) and C. albicans (10) strains, whereas from patients hospitalized in conservative wards most often C. albicans (6) strains were isolated. Candida strains were mostly susceptible to antifungal agents tested. It was interesting to culture Trichosporon beigelii (T. cutaneum) strain as an etiological agent of fungemia. This strain was multidrug-resistant.     

Prevalence of Enterotoxigenic Staphylococci in Nose,Throat and Skin Lesions in Meat-Workers

The frequency of enterotoxigenic coagulase-positive and coagulase-negative staphylococci in nose and throat and in hand lesions was investigated in 86 meat cutters and dressers. Enterotoxin-producing staphylococci were demonstrated in nasal swabs from 22% of clinically well workers and from 42% of a group with mild coryza. The corresponding rates in throat swabs were 6 and 12%. Four of 16 superficial lesions of the hand harbored enterotoxigenic staphylococci. The implications for contamination of food and outbreaks of staphylococcal food poisoning are discussed.     

Identification of Candida albicans using the chromogenic medium Albicans ID

The correct identification of the microrganism is the base for epidemiological studies and treatment of infections. The aim of our study was to evaluate the efficacy of the chromogenic media Albicans ID (bioMerieux, France) in the identification of Candida albicans. A total of 190 yeasts strains were evaluated in the study. A rate of 100% of all C. albicans (80) and Candida dubliniensis (five) strains exhibited blue color. Nevertheless, the blue color was also observed with cultures of Candida rugosa (3/5) and Candida tropicalis (3/17). Albicans ID cromogenic media presented specificity rate of 90% and positive and negative predictive values of 88% and 100%, respectively, in the identification of C. albicans.     

Yeast-like fungi as etiologic agents of blood infections in patients hospitalized in 1998-1999

The aim of the study was the analysis of frequency of yeast-like fungi as etiological agents of fungemias in patients hospitalized in operative and conservative wards of Medical Academy Central Clinical Hospital in Warsaw in 1998-1999. Peripheral blood samples and collected from vascular catheters were incubated in BacT/Alert system(Organon Teknika, USA). Positive blood samples were inoculated on Sabouraud medium with chloramphenicol (bioMerieux, France) (the time of cultivation from 48 h to 7 days at 30 C) and on chromogenic medium BBL CHROMagar Candida (Becton Dickinson, USA). Fungal strains were identified by standard mycological procedures using ID 32 C strips (ATB system, bioMerieux, France) and tests of Sanofi Diagnostics Pasteur (France). The total number of positive blood cultures was 1724. Fifty eight fungal strains were isolated from blood samples (3.36%). Strains belonged to 4 genera: Candida (55), Trichosporon (1), Saccharomyces (1) and Pichia (1). Thirty eight fungal strains were isolated from peripheral blood samples. Forty seven fungal strains were cultured from patients hospitalized in operative wards. Among fungi isolated from peripheral blood samples C. albicans (10), C. glabrata (9) and C. parapsilosis (5) strains dominated. From blood samples collected from vascular catheters most often C. albicans (7), C. glabrata (4) and C. parapsilosis (3) were isolated.     

Evaluation of a new chromogenic medium (Candida ID) for the isolation and presumptive identification of Candida albicans and other medically important yeasts

Candidiasis is a frequent human infection caused mainly by Candida albicans. However, other species are emerging as important pathogens, as Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei or Candida guilliermondii. Rapid identification of clinical isolates could facilitate diagnosis and treatment. Candida ID (bioMerieux, Spain) is a new medium for the isolation and presumptive identification of yeasts: C. albicans grows as blue colonies, and C. tropicalis, C. guilliermondii, Candida kefyr and Candida lusitaniae as pink ones. The utility of Candida ID was evaluated with more than 700 clinical isolates and type culture collection strains from different genera including Candida, Cryptococcus, Saccharomyces, and Rhodotorula. Presumptive identification was confirmed by germ tube test, microscopic morphology and chlamydoconidia production on corn meal agar and carbohydrate assimilation on API-ATB ID 32C or Vitek (bioMerieux). Growth on Candida ID was rapid (18-24 h) for most of the yeast strains tested. Sensitivity and specificity of identification of C. albicans was significantly high (>98%), since a very low number of isolates were found to be false negative or false positive. A better result was obtained for species growing as pink colonies (>99.5%). Detection of different species of medical important yeasts was easy with Candida ID, as perfectly distinct colors and textures of colonies were observed on this medium. Candida ID allowed the discrimination between C. glabrata (creamy and smooth) and C. krusei (rough and white) colonies. Other species showed different colony textures and colours, white being the predominant colour. Candida ID was very useful for the presumptive identification C. albicans isolates.     

Evaluation of the use of the bioMerieux Rapid ID32 A for the identification of Clostridium botulinum

The neurotoxins produced by Clostridium botulinum are amongst the most potent known to man. Toxin production is detected by a mouse bioassay, which requires several days for a result and is not acceptable for routine use unless there is a high level of suspicion. The Rapid ID32 A kit produced by bioMerieux gives an identification of an isolate within 4 h. The aim of this study was to examine the efficiency of the identification of Cl. botulinum using the Rapid ID32 A. Forty-two strains of Cl. botulinum , one strain each of botulinum toxin-producing Cl. butyricum and Cl. baratii , and four strains of Cl. sporogenes , were tested. One strain of Group I Cl. botulinum gave a presumptive identification of Group II Cl. botulinum , six strains of Cl. botulinum were identified as 50–98% Cl. botulinum in some tests, and 17 strains of Cl. botulinum were identified as <50% Cl. botulinum. Thirteen strains of Cl. botulinum were identified as >99% Cl. sporogenes or 86% Cl. histolyticum , and five strains gave a combination of these results. All strains of Cl. sporogenes were correctly identified. These results show that some strains of Cl. botulinum may not be correctly identified using the Rapid ID32 A.     

Evaluation of a rapid culture-based screening test for detection of methicillin resistant Staphylococcus aureus

The performance of a culture based assay, BacLite Rapid MRSA for the rapid detection (5 hours) of methicillin resistant Staphylococcus aureus (MRSA) from specimens (n = 377) obtained from nares, throat, wounds and perineum was investigated. Compared to culture based reference methods (chromogenic MRSA ID (bioMerieux)), selective enrichment broth, PBP2' latex agglutination (Oxoid) and VITEK 2 identification (bioMerieux), an overall sensitivity of 71% with a 82% specificity and a negative predictive value (NPV) of 95% was provided. The Baclite test is rapid and easy to use and has the advantage of a culture-based detection method for MRSA.     

Determination of methicillin resistance in clinical strains of Staphylococcus aureus in routine microbiological diagnostics

The aim of this study was to compare the results of two methods: disc-diffusion test and ATB STAPH 5 (version 2000) test applied for determination of methicillin-resistant staphylococci. One hundred and twenty S. aureus strains isolated from clinical specimens in microbiological laboratory of Medical University in Warsaw were investigated. Identification and drug resistance were determined using automatic ATB Expression System. We compared the results of methicillin-resistant S. aureus detection by disc-diffusion method (oxacillin 1 microg) and ATB STAPH 5; version 2000 (bioMérieux sa). In the case of 116 strains S. aureus identical results were obtained in both methods, 4 strains gave inconsistent results in these two methods. Results that were obtained show that the ATB STAPH 5 (version 2000) test is as useful for routine determination of MRSA and MSSA strains as the disc-diffusion method, and may be used alternatively.     

In-vitro bacteriocin-mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. mitior produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1-12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher (P less than 0.001, chi 2 test and P less than 0.05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus (P less than 0.001 and P less than 0.01) and of oral Staph. epidermidis over oral Staph. aureus (P less than 0.01 and P less than 0.05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological viewpoints are discussed.     

Evaluation of six commercial identification kits for the identification of Staphylococcus aureus isolated from bovine mastitis

AIMS: Comparison of six commercially available in human medicine well-established slide agglutination systems for the identification of Staphylococcus aureus. METHODS AND RESULTS: Slide agglutination tests were compared with the conventional tube coagulase test, biochemical identification and with the molecular identification by polymerase chain reaction (PCR) amplification of species-specific parts of the gene encoding the 23S RNA. Systems evaluated included Masta-Staph (Mast Diagnostics), Staphylase-Test (Oxoid), Staphytect-Plus (Oxoid), Staphyloslide Latex (Becton Dickinson), Slidex Staph Plus (bioMerieux) and Dry Spot Staphytect Plus (Oxoid). A total of 141 staphylococcal strains isolated from cases of bovine mastitis including 90 S. aureus, 14 Staphylococcus epidermidis, 10 Staphylococcus warneri, 13 Staphylococcus xylosus, 11 Staphylococcus haemolyticus and three other coagulase-negative staphylococci were tested with each method. Staphylococcus aureus strains were selected by macrorestriction analysis with pulsed field gel electrophoresis (PFGE). Only genetically unrelated strains were included in the study. The sensitivities and specificities of the test were as follows: Masta-Staph 86.7 and 90.1%, Staphylase-Test 78.4 and 85.1%, Staphytect-Plus 81.1 and 86.5%, Staphyloslide Latex 77.8 and 84.4%, Slidex Staph Plus 77.8 and 84.4%, Dry Spot Staphytect Plus 75.6 and 83.0%. CONCLUSIONS: The results of this evaluation suggest that the six slide agglutination methods tested can provide rapid identification of S. aureus also from bovine mastitis. The sensitivity and specificity seems to be less than those reported from human S. aureus isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the first comparative reported investigations about the applicability of different commercially available slide agglutination tests for the detection of S. aureus from bovine mastitis using PFGE selected clinical isolates.     

Staphylococci in orthopaedic surgical wounds.

From 50 infected surgical wounds of orthopaedic patients, 43 (86%) staphylococcal strains were isolated. 34 of all these staphylococci belonged to Staphylococcus aureus species (i.e. 68 % of all isolates from surgical wounds; 79% of staphylococcal isolates); 9 were coagulase-negative staphylococci (i.e. 21% of all isolates from surgical wounds; 18% of staphylococcal isolates). Among microorganisms isolated from the wounds we also found 2 (4%) of the Enterobacteriaceae family; 2 (4%) of the Pseudomonas genus; 3 (6%) of the Streptococcus genus. Thus, orthopaedic surgical wounds were infected by staphylococci (mainly S. aureus) more frequently than by other micro-organisms. All the staphylococcal strains were screened for methicillin resistance by agar disk diffusion testing and for the presence of mecA gene responsible for methicillin resistance by PCR. 32% of the S. aureus and 33% of the S. epidermidis strains resulted methicillin resistant and mecA-positive. The data confirm the diffusion of methicillin resistant S. aureus in surgical site infections and shows that the so-called "new pathogens", i.e. S. epidermidis and other coagulase-negative staphylococci, also exhibit a frequent and hazardous methicillin-resisting ability.     

In-vitro bacteriocin-mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. minor produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1–12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher ( P < 0·001, χ² test and P < 0·05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus ( P < 0·001 and P < 0·01) and of oral Staph. epidermidis over oral Staph. aureus ( P < 0·01 and P < 0·05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological veiwpoints are discussed.     

ESBL-positive strains of the Bacteroides fragilis group isolated from patients at the regional hospital center in Płock (Poland)

The aim of this study was to confirm a presumptive qualification of clinical B. fragilis group strains isolated in P?ock as ESBL-positive strains and to determine some properties of these strains. Twenty four clinical strains belonging to the B. fragilis group, isolated first of all from surgical patients, were received for testing. Identification of strains was performed in the automatic ATB Expression system (bioMerieux sa, France) using biochemical API 20 A strips. Strains were tested for the production of catalase (ID Color Catalase test, bioMerieux sa) and beta-lactamase (Cefinase, BBL, Becton Dickinson, USA). Susceptibility of strains to four antimicrobial agents: clindamycin, metronidazole, amoxicillin/clavulanic acid and imipenem was determined by Etest (AB Biodisk, Sweden). ESBLs were detected with the use of two disc diffusion methods: the double-disc synergy test (DDST) according to Jarlier et al. and the diagnostic disc (DD) test according to Appleton. Seventeen of examined strains belonged to the species Bacteroides fragilis, three--to B. ovatus/thetaiotaomicron, two--to B. distasonis, one--to B. uniformis and one--to B. stercoris/eggerthii. One strain (B. uniformis) did not produce catalase, whereas all strains produced beta-lactamases. Examined strains were susceptible in vitro to metronidazole, amoxicillin/clavulanic acid and imipenem. One clindamycin-resistant strain was detected (B. fragilis). Occurrence of ESBL-type enzymes was confirmed in 22 strains of following species: B. fragilis (17 strains), B. ovatus/thetaiotaomicron (3), B. distasonis (1) and B. uniformis (1). Clinical strains of the B. fragilis group with a new mechanism of resistance to beta-lactam antibiotics appeared during last years in Poland. They produce extended-spectrum beta-lactamases (ESBLs), so they are resistant to penicillins, cephalosporins and monobactams. Monitoring of infections caused by these threatening strains in hospital patients is very important.     

The results and characteristics of the mupirocin (Bactroban) sanative treatment of intranasal Staphylococcus carriers in a large hospital]

The action of mupirocin as a nasal ointment (Bactroban) was studied on intranasal carriers of the hospital staphylococcal strains. The study included 37 medical workers from different and mainly problem units of the large general hospital. The tolerability of the ointment was good. After the Bactroban use no complications of the patients were recorded. The efficacy of Bacroban by the microbiological criteria in total amounted to 100 per cent. The eradication of methicillin resistant Staphylococcus aureus (MRSA) was observed in 93 per cent of the cases. A decrease of the level of the nasal passages dissemination by MRSA and methicillin resistant coagulase-negative staphylococci (MRSC) up to such low titers as 100 and 90 per cent was stated. No difference in the action of Bactroban on MRSA, MSSA and MRSC was noted. The bacteriological monitoring for 3 to 4 months revealed a change of the staphylococcal strains in 94 per cent of the cases, recolonization by the same staphylococcal strain in 19 per cent, recolonization by some another staphylococcal strains in 33 per cent and no recolonization in 14 per cent. A stable decrease of staphylococcal strains was possible with simultaneous Bactroban sanitation of all the bacterial carriers of the hospital or its isolated unit.     

Membrane protein spectra of staphylococci from a comparative physiological aspect]

Membrane protein spectra, obtained by electrophoresis in the system polyacrylamide gel--sodium dodecysolfate, were studied in 14 staphylococcal strains with different properties. The proteinograms of membranes were shown to be useful as an additional criterion in the identification of staphylococci. Fractions and their combination characteristic of all the strains and their separate groups were revealed in the protein spectra of staphylococcal membranes.     

Characterization of the yeast flora present in some Turkish high-sugar products

In this study, 129 Turkish high-sugar products were examined in terms of their yeast flora and 73 representative strains were isolated. Yeast isolates were identified at species level by using Apilab Plus (bioMérieux, France), a specific computer program developed for ID 32C strips (bioMérieux, France). While one of the isolates could be identified at genus level as Aureobasidium, 66 of them were identified as 21 species belonging to 8 different genera. The distribution of these isolates were as follows: Candida (38), Rhodotorula (8), Zygosaccharomyces (7), Cryptococcus (6), Saccharomyces (3), Debaryomyces (2), Pichia (1) and Torulaspora (1). Approximately 70% of the isolates were found to have the ability to grow on media with 50% (w/w) glucose. Hence, they were characterized as xerotolerant strains. Although Zygosaccharomyces rouxii is known as the most xerotolerant yeast species, only two strains of Z. rouxii could be isolated from Turkish high-sugar foods. During identification studies, it was observed that ID 32C test strips should certainly be supported by morphological and physiological tests for obtaining more reliable identification results. If not, closely related yeast species such as anamorph and telemorph forms can not be distinguished.     

Biofilm production, a marker of pathogenic potential of colonizing and commensal staphylococci

Biofilm is one of the known virulence factors of staphylococci, a human and animal pathogen and commensal. Some of the strains become invasive under favorable conditions while others do not cause disease. Early detection and management of potentially pathogenic staphylococci is the essential step to prevent device-associated infections. There is also a need to evaluate one simple method for the detection of potential pathogens. Hence this study was planned to study the difference in potential of commensal, colonizing and invasive strains of staphylococci to produce biofilm. We used one qualitative (Congo red agar) and one quantitative (microtiter plate) method for detection of biofilm production and evaluated the sensitivity and specificity of Congo red agar method by using microtiter plate method as a gold standard. We consecutively enrolled staphylococcal strains isolated from peripheral intravenous device (IVD), venous blood, site of IVD insertion and nasal mucosa of patients admitted to pediatric ward with peripheral intravenous devices in place for more than 48 h. Total 100 invasive, 50 colonizing and 50 commensal isolates were studied. Of 100 invasive isolates 74% (74/100) were biofilm positive while only 68% (34/50) colonizing and 32% (16/50) commensal isolates were biofilm positive. The difference in biofilm production by commensal, colonizing and invasive strains was statistically significant (p<0.0001). Sensitivity and specificity of Congo red agar test for detection of biofilm producers were 90.63% and 90.79% for Staphylococcus aureus and 75.86% and 96.88% respectively for coagulase negative staphylococci. CRA is a method that could be used to determine whether an isolate has the potential for biofilm production or not.