Identification Of Gram-positive Cocci Research Articles

Detection of some food poisoning bacteria in some semi cooked chicken meat products marketed at Kaliobyia governorate

Ninety random samples of semi cooked chicken meat products represented by strip, pane and nuggets (30 of each) were collected from different supermarkets at Kaliobyia governorate for bacteriological examination.The mean values of Aerobic plate count,Enterobacteriacea count and Staphylococcus count were4.9x104 ± 1.2x104, 3.1x102 ± 8.2x102 and1.5x102 ±7.1x10 for chicken strips, 8.4x104± 3.3x104,8.9x102 ± 5.6x102and7x103 ± 4.5x103 cfu/g for chicken pane and 7.46x104 ± 1.7x104,1.2x102 ± 2.1x10 and 7.2x103 ± 2.3x103cfu/g for chicken nuggets. Moreover, the incidence of S.entretidis was 6.6% for chicken strips and not detected in pane and nuggets. Staph aureus incidence was 20%, 26.6%and 26.6% for chicken strips, pane and nuggets for total examined samples by using conventional culture method. For more confirmation, identification of Staph.aureus from 5 random samples by Vitek 2 compact system was applied. Results recorded was identical to that of culture method with accuracy 100% for examined chicken products samples and showed that the Vitek 2 system is a suitable tool for rapid and direct identification of gram positive cocci as an ideal detection system should include high specificity and sensitivity; fast response time; capability for mass production; simplification of sample preparation steps ;minimal perturbation of sample;and providing continuous data analysis as that obtained by the Vitek 2compact system. The public health importance of isolated microorganisms and recommended point were discussed.

Prevalence of some food poisoning bacteria in semi cooked chicken meat products at Kaliobyia governorate with using of recent Vitek 2 compact and PCR techniques

Bacterial food borne pathogens are important food safety issue worldwide .Rapid and accurate identification of bacteriological pathogen isolated from food staff is important both for food quality assurance and for the tracing of outbreaks of bacterial pathogen.A grand total of ninety random samples of semi cooked chicken meat products represented by strips, pane and nuggets (30 of each)were collected from different supermarkets at Kaliobyia governorate for bacteriological examination using conventional culture method and rapid modern techniques as Vitek 2 compact system and molecular identification by PCR technique. The obtained results revealed that Staph aureus and E.coli incidence were 20% and 10% in strips, 26.6%and 13.3% in chicken pane and26.6% and 23.3%in nuggets for total examined samples.Also,the serologically identified E.coli were O127, O128, O153, O157 and O91 from examined samples. . Staphylococcus aureus and E. coli were identified in all examined samples by confirmatory identification using Vitek 2 compact system in examined 10 random samples of the chicken products. Result recorded accuracy 100% for examined samples and showed that the Vitek 2 system is a suitable tool for rapid and direct identification of gram positive cocci and gram negative bacilli from chicken products. Using of PCR technique revealed that there were one or more virulence genes in E.coli (stx1&stx2) strains isolated from the examined samples of chicken products.

Comment on "Intravitreal Ampicillin Sodium for Antibiotic-Resistant Endophthalmitis: Streptococcus uberis First Human Intraocular Infection Report".

In the paper by Velez-Montoya et al. [1], the authors reported the first description of a case of intraocular infection in humans caused by an antibiotic-resistant strain of Streptococcus uberis. We would like to point out that the absence of any description of the method used for bacteria identification in this paper raises some concerns related to the possibility of a misidentification of this bacterium as a pathogen affecting the human eye. S. uberis is an environmental pathogen responsible for a high proportion of cases of clinical and subclinical mastitis in ruminant and nonruminant species [2]. The nutritional flexibility associated with an assortment of metabolic options allows S. uberis to occupy a discrete ecological niche [3]. Some studies have hypothesized that the flexibility of this bacterium under various environments and conditions might possibly favour infection also in humans [4, 5]. However, the evidence and putative role of S. uberis as a human pathogen are very limited and the methods used for the identification are frequently questionable [6]. In fact, phenotypic bacterial identification by commonly used systems such as Vitek, Facklam scheme, and similar conventional methods has been generally employed. However, in most cases of supposed human infections by S. uberis these techniques showed a low level of accuracy [6, 7]. Facklam described a case of human infection where all the isolates, previously classified as S. uberis, have been subsequently identified as Globicatella sanguinis [7] and a consistent body of evidence supports the notion that one of the most recurrent mistakes in the identification of gram-positive cocci, using phenotypic bacterial identification methods, is represented by the lack of distinction between S. uberis and Enterococcus spp. [8, 9]. A conventional scheme for the identification of S. uberis strains isolated from bovine milk samples and based on 11 biochemical tests also showed 6% frequency of misidentifications between S. uberis and Enterococcus faecalis [10]. On the other hand, infections caused by E. faecalis are largely described in the literature [11–17]. E. faecalis is known to represent a virulent pathogen frequently associated with endophthalmitis with very poor clinical prognosis [14, 18]. Endophthalmitis caused by E. faecalis has been described in a diabetic patient after biliary surgery [19], while other reports described ocular infections after cataract extractions [20–22]. Recently Bains et al. and Tang et al. also reported the emergence of endophthalmitis caused by E. faecium vancomycin-resistant strains [23, 24]. Indeed, the intraocular infections caused by E. faecium previously described in the literature are not in contrast with the image reported in Figure 1(b) of the paper by Velez-Montoya et al. [1]. In conclusion the phenotypic bacterial identification systems have been repeatedly found to fail the classification of E. faecalis on behalf of S. uberis. Thus, in our opinion the absence of any detailed description of the technique used for the bacterium identification in the paper by Velez-Montoya et al. [1] raises some concern since the method of identification may affect the validity and reliability of the diagnosis. Therefore we consider some information from the authors necessary regarding the description of the methods used for the identification, particularly considering that this might represent the first case of human intraocular infection caused by S. uberis and also in consideration that the pathogenic potential of this bacterium in humans is still under debate.

Identification of Gram-Positive Cocci by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Comparison of Different Preparation Methods and Implementation of a Practical Algorithm for Routine Diagnostics

This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

Estudo bacteriológico do lavado broncoalveolar na gestão de antibióticos na pneumonia associada à ventilação mecânica de pacientes em unidades de terapia intensiva cirúrgica

To determine the correlation of Gram staining with the culture of bronchoalveolar lavage in patients with clinical features of ventilator-associated pneumonia from two adult trauma and surgical intensive care units. We conducted a retrospective study of 252 samples of bronchoalveolar lavage from patients with clinical ventilator-associated pneumonia in trauma or surgical postoperative care. Gram staining samples were classified as Gram-positive cocci and Gram-negative bacilli, all other results being excluded. Cultures from bronchoalveolar lavage were compared with Gram staining results. The correlation between Gram staining and culture from the bronchoalveolar lavage showed a kappa index of 0.27. The sensitivity of Gram staining was 53.9% and the specificity, 80.6%. Considering the identification of Gram-positive cocci against other results (negative and Gram-negative bacilli), the negative predictive value was 94.8%. The evaluation of Gram-negative bacilli against other results (negative and Gram-positive cocci) rendered a sensitivity of 27.1% and a specificity of 95.4%. It appears that the negative predictive value for Gram-positive cocci is acceptable, but the sensitivity of Gram staining in the etiology of ventilator-associated pneumonia was not able to identify the microorganism before culture.

A comparative study of two different methods of sample preparation for positive blood cultures for the rapid identification of bacteria using MALDI-TOF MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has lately been implemented as a solid technology for rapid microorganism identification in microbiology laboratories. This study compares two methods for bacterial separation from 85 positive blood culture before MALDI-TOF MS: (1) a conventional method that we used in our laboratory to prepare bacteria for susceptibility testing and (2) a new commercialized technique (Sepsityper). There were no significant differences in the identification of Gram-negative bacilli regardless of the bacterial separation method used. However, identification was greater for Gram-positive cocci when the Sepsityper method was used (84.15% vs. 100% in the identification to a genus level in staphylococci and 57.14% vs. 85.71% in the identification to a genus level of enterococci with the in-house and Sepsityper methods, respectively). Therefore, the Sepsityper method to prepare bacteria from a positive blood culture is more adequate for the further identification of Gram-positive cocci by MALDI-TOF MS.

Successful modification and development of the accuProbe technique for identification of gram-positive cocci directly from blood culture

Successful modification and development of the accuProbe technique for identification of gram-positive cocci directly from blood culture

Comparative Study Using Various Methods for Identification of Staphylococcus Species in Clinical Specimens

Coagulase-negative staphylococci (CNS) play a predominant role in nosocomial infections. Rapid, reliable identification of these organisms is essential for accurate diagnosis and prompt effective treatment of these infections. Quite recently, the VITEK 2 g-positive (gram-positive [GP]) identification card (bioMérieux) has been redesigned for greater accuracy in the identification of gram-positive cocci. We compared the BD Phoenix (Becton Dickinson) and VITEK 2 (bioMérieux) automated microbiology systems, using their respective update version cards, and the API ID32 STAPH test. The glyceraldehyde-3-phosphate dehydrogenase (gap) gene-based T-RFLP (terminal restriction fragment length polymorphism) method was used for verifying the results. In total, 86 clinical isolates of CNS and 27 reference strains were analyzed. The results show that for identification of CNS, the automated identification methods using the newest VITEK 2 and BD Phoenix identification cards are comparable. However, API ID32 STAPH revealed more correct results compared to both automated microbiology systems. Despite the increased performance of the phenotypic automated identification systems compared to the former versions, molecular methods, e.g., the gap-based T-RFLP method, still show superior accuracy in identifying Staphylococcus species other than Staphylococcus aureus.

Performance of the New VITEK 2 GP Card for Identification of Medically Relevant Gram-Positive Cocci in a Routine Clinical Laboratory

The VITEK 2 gram-positive (GP) identification card (bioMerieux, Marcy l'Etoile, France) has been redesigned to achieve greater accuracy in the identification of gram-positive cocci. A total of 43 biochemical tests, including 17 enzymatic tests, are present in the card and interpreted in a kinetic mode, for up to 8 h. The VITEK 2 database, used in conjunction with the GP identification card, allows the identification of 115 different taxa. A total of 364 strains of GP cocci (217 Streptococcaceae strains and 147 Micrococcaceae strains) belonging to 31 taxa were tested with the new VITEK 2 GP identification card. Of the 364 strains, 105 were taken from routine primary plating media. A total of 344 strains (94.5%) were correctly identified to the species level and 17 strains (4.7%) were identified with low discrimination, requiring additional tests, whereas 1 strain (0.3%) was incorrectly identified and 2 strains (0.5%) remained unidentified. Within 7 h of the start of incubation, more than 90% of all strains were identified. Of the 105 primary cultures, 97% were correctly identified to the species level, 2% were identified with low discrimination, and 1% remained unidentified. Identification performance data were independent of each of the three plating media used. It is concluded that the new VITEK 2 GP identification card provides reliable results for the identification of GP cocci under routine laboratory conditions.

Isolation, Enumeration, and Identification of Gram-Positive Cocci from Frozen Crabmeat

Bacterial levels in frozen crabmeat samples were determined by plate counts using four staphylococcal isolation media incubated for 24, 48, and 72 h at 26 and 35°C. Staphylococcal counts determined by the spread-plate Food and Drug Administration Baird-Parker protocol incubated at 35°C for 48 h (FDABP48-35) served as the standard for comparison. When FDABP48-35 counts were compared to counts from 29 combinations of media, time of incubation, and incubation temperature, only FDABP and Borrego, Florido, Mrocek, and Romero (BFMR) counts, representing 11 combinations, were statistically comparable to FDABP48-35 counts. Cocci (91.5%) were the dominant bacterial type; gram-positive rods (8.3%) and gram-negative isolates (0.2%) were also detected. Isolates tested by the coagulase reaction were predominantly coagulase negative (CN) (97.7%). Of 100 isolates analyzed by the BIOLOG identification procedure, 62% were classified as Staphylococcus lentus, S. hominis, and S. epidermidis. Three isolates were identified as Staphylococcus aureus. These data indicate that species identification of staphylococci from crabmeat can assist in determining the source of contamination, and that staphylococcal isolates from crabmeat are more likely to be coagulase negative.

THE IDENTIFICATION OF GRAM-NEGATIVE PLEOMORPHIC BACILLI, WITH SPECIAL REFERENCE TO A CASE OF HEMOPHILUS APHROPHILUS ENDOCARDITIS.

A study of a Gram-negative pleomorphic organism, Hemophilus aphrophilus, isolated from the blood of a patient with clinical bacterial endocarditis, presented a problem in identification. The literature on bacteriologic technic is replete with detailed methods for the isolation and identification of Grampositive cocci and Gram-negative enteric bacilli. However, little clear-cut information is given on the differentiation of Gram-negative pleomorphic organisms belonging to the genera Hemophilus, Pasteurella, Brucella, or Actinobacillus. Ordinarily these organisms have been thought of in relation to well defined clinical situations, i.e., Hemophilus influenzae from the nasopharynx or spinal fluid of an infant, or else to be of such rare occurrence, i.e., Pasteurella pestis, as not to present a problem in the routine hospital laboratory. Upon perusal of the recent literature, however, several reports of unusual types of human infection due to organisms of the Gram-negative pleomorphic type are noted. These reports cite the increased frequency of human infections caused by previously undescribed organisms, and refer to bacteria previously regarded as animal pathogens. Several articles contain statements affirming the ease with which these organisms may be confused with other bacteria and give complete morphologic, biochemical, and serologic characterization of the particular organism under discussion, but fail to indicate how these organisms might effectively be differentiated in the routine hospital laboratory. That this problem is not unique to our laboratory became apparent when we submitted the organism to other laboratories where similar difficulties were experienced. The organism in our case was finally identified by the staff of the Communicable Disease Center in Atlanta, Georgia.