Pathogenic Gram-positive Cocci Research Articles

Indoor Air Pollution and Its Determinants in Household Settings in Jaipur, India

Individuals spend 90% of their time indoors, primarily at home or at work. Indoor environmental factors have a signifcant impact on human well-being. It was a longitudinal study that assessed the major factors that reduce indoor air quality, namely particulate matter, and bio-aerosols, using low-cost sensors and the settle plate method, respectively also to determine the effect of atmospheric parameters and land use patterns in households of commercial, industrial, residential, slum, and rural areas of the city. PM2.5 concentration levels were similar in most parts of the day across all sites. PM10.0 concentration levels increased indoors in a commercial area. PM2.5 concentration showed a negative correlation with temperature and a positive correlation with relative humidity in some areas. Very high values of PM2.5 concentration and PM10.0 concentration have been observed in this study, inside households of selected rural and urban areas. Pathogenic gram-positive cocci, gram-positive rods, Aspergillus, and Mucor species were the most common bacterial and fungal species respectively found inside households. This study examined particulate matter concentration along with bio-aerosols, as very less studies have been conducted in Jaipur the capital of Rajasthan, a state in the western part of India which assessed both of these factors together to determine the indoor air quality. Rural households surrounding the periphery of the city were found to have similar pollution levels as urban households. So, this study may form the basis for reducing pollution inside households and also for taking suitable measures for the reduction of pollution in the indoor environment.

Justification of the priority controlled sanitary-microbiological parameters to ensure the safety of hospital environment, medical organizations stationary type, regardless of their functional purpose

Introduction. The work is devoted to evaluating the results of our own research of sanitary-microbiological monitoring of environmental objects in diversified treatment-and-prophylactic institutions of stationary type and of the analysis both of domestic and foreign data in order justify of the list of priority controlled sanitary-microbiological indices of air and surfaces to ensure the safety of hospital environment, medical organizations stationary type, regardless of their functional purpose. Material and methods. The survey was conducted in various premises in the medical-prophylactic institutions of stationary type for two years. Studies included determination of microbial contamination of the air environment, working surfaces, hands of personnel with the detection of bacteriological, virological, and mycological parameters, followed by macroscopic and microscopic identification of microorganisms and identification using automated systems with the method of time-of-flight matrix-assisted laser mass spectrometry platform MALDI-TOF, based on the study of the mass spectra of ribosomal proteins in the range of 1000-10000 Daltons and bioinformatic comparison of the obtained spectrum with database reference spectra and PCR. Results. As a result, the research of surface washings in the premises of a multidisciplinary clinic revealed microbial contamination with conditionally pathogenic gram-positive cocci, including S.aureus, gram-positive and gram-negative bacteria posing a serious epidemiological danger to patients in these wards regardless of the MOST profile and requires mandatory monitoring taking into account of the used disinfectants. Conclusion. Our own research and analysis of domestic and foreign literature showed that it is not enough to monitor the air in the MOST premises only in terms of total microbiological contamination. In the operating, procedural and dressing blocks, as well as in the wards, physiotherapeutic, diagnostic, laboratory rooms and auxiliary units, it is also necessary to take into account other sanitary and microbiological indices: total microbes count, gram-positive rods and cocci, including S.aureus, fungi, adeno-, entero-, astroviruses, coliphages.

Justification of the priority controlled sanitary-microbiological parameters to ensure the safety of hospital environment, medical organizations stationary type, regardless of their functional purpose

Introduction. The work is devoted to evaluating the results of our own research of sanitary-microbiological monitoring of environmental objects in diversified treatment-and-prophylactic institutions of stationary type and of the analysis both of domestic and foreign data in order justify of the list of priority controlled sanitary-microbiological indices of air and surfaces to ensure the safety of hospital environment, medical organizations stationary type, regardless of their functional purpose. Material and methods. The survey was conducted in various premises in the medical-prophylactic institutions of stationary type for two years. Studies included determination of microbial contamination of the air environment, working surfaces, hands of personnel with the detection of bacteriological, virological, and mycological parameters, followed by macroscopic and microscopic identification of microorganisms and identification using automated systems with the method of time-of-flight matrix-assisted laser mass spectrometry platform MALDI-TOF, based on the study of the mass spectra of ribosomal proteins in the range of 1000-10000 Daltons and bioinformatic comparison of the obtained spectrum with database reference spectra and PCR. Results. As a result, the research of surface washings in the premises of a multidisciplinary clinic revealed microbial contamination with conditionally pathogenic gram-positive cocci, including S.aureus, gram-positive and gram-negative bacteria posing a serious epidemiological danger to patients in these wards regardless of the MOST profile and requires mandatory monitoring taking into account of the used disinfectants. Conclusion. Our own research and analysis of domestic and foreign literature showed that it is not enough to monitor the air in the MOST premises only in terms of total microbiological contamination. In the operating, procedural and dressing blocks, as well as in the wards, physiotherapeutic, diagnostic, laboratory rooms and auxiliary units, it is also necessary to take into account other sanitary and microbiological indices: total microbes count, gram-positive rods and cocci, including S.aureus, fungi, adeno-, entero-, astroviruses, coliphages.

Asymptomatic carriage of antibiotic-resistant Gram-positive cocci among different background populations in East Timor, Southeast Asia.

Dissemination of pathogenic multiresistant bacteria is of public health concern. Reliable data can be difficult to obtain, especially in developing countries. This work aimed to characterize the skin and oropharyngeal microbiota, as well as their antimicrobial resistance profiles, of East-Timor populations to identify potentially pathogenic Gram-positive cocci. In order to assess the prevalence of pathogenic bacteria in East-Timor, the oropharyngeal and skin microbiota of 74 individuals was characterized. Gram-positive cocci were evaluated and their antimicrobial resistance profiles were determined. A total of 228 oropharyngeal and 278 skin samples were obtained. The population consisted of 36.5% of asymptomatic carriers of Gram-positive cocci. Kocuria rosea (n = 7, 19.4%), Staphylococcus spp. (n = 6, 16.7%), and Micrococcus luteus (n = 6, 16.7%) were isolated, among others. Antimicrobial resistance levels ranged between 0% and 36.1%, and a multiresistance profile was observed in one third of the isolates. Gram-positive cocci colonization was associated with age group. Prevalence of multiresistant isolates was higher in males who were sampled at the refugee camp. Results show that the prevalence of antimicrobial resistance on East Timor may be underestimated. This study represents the first step toward the full characterization of potential pathogenic Gram-positive cocci present in the populations from East Timor.

An Uncharacterized Member of the Gls24 Protein Superfamily Is a Putative Sensor of Essential Amino Acid Availability in Streptococcus pneumoniae

Proteins belonging to the Gls24 superfamily are involved in survival of pathogenic Gram-positive cocci under oligotrophic conditions and other types of stress, by a still unknown molecular mechanism. In Firmicutes, this superfamily includes three different valine-rich orthologal families (Gls24A, B, C) with different potential interactive partners. Whereas the Streptococcus pneumoniae Δgls24A deletion mutant experienced a general long growth delay, the Δgls24B mutant grew as the parental strain in the semisynthetic AGCH medium but failed to grow in the complex Todd-Hewitt medium. Bovine seroalbumin (BSA) was the component responsible for this phenotype. The effect of BSA on growth was concentration-dependent and was maintained when the protein was proteolyzed but not when heat-denatured, suggesting that BSA dependence was related to oligopeptide supplementation. Global transcriptional analyses of the knockout mutant revealed catabolic derepression and induction of chaperone and oligopeptide transport genes. This mutant also showed increased sensibility to cadmium and high temperature. The Δgls24B mutant behaved as a poor colonizer in the nasopharynx of mice and showed 20-fold competence impairment. Experimental data suggest that Gls24B plays a central role as a sensor of amino acid availability and its connection to sugar catabolism. This metabolic rewiring can be compensated in vitro, at the expenses of external oligopeptide supplementation, but reduce important bacteria skills prior to efficiently address systemic virulence traits. This is an example of how metabolic factors conserved in enterococci, streptococci, and staphylococci can be essential for survival in poor oligopeptide environments prior to infection progression.

In vitro antimicrobial activity of common species of seaweeds native to Trinidadian coasts

Marine macrophytes have been recently recognized as promising sources of bioactive molecules and as such many drugs leads have arisen from them. We investigated the antibacterial activity of methanol extracts of seaweeds against several human pathogens. Among the seaweeds screened, three species showed inhibitory effects against at least one pathogen, with Ulva fasciata and Amphiroa rigida exhibiting bacteriostatic activity and Chaetomorpha crassa showing bactericidal action against pathogenic Gram-positive cocci. Further testing revealed that the extracts of Chaetomorpha crassa displayed the ability to inhibit biofilm formation and virulence gene expression in Methicillin resistant Staphylococcus aureus (MRSA). Isolation and identification of the bioactive molecules of Chaetomorpha crassa revealed the two free fatty acids stearic acid and linolenic acid. This research shows that several species of marine plants found in Trinidad comprise bioactive compounds and may be good candidates for further investigations aimed at isolating and evaluating these compounds for potential medical applications.

The PavA-like Fibronectin-Binding Protein of Enterococcus faecalis, EfbA, Is Important for Virulence in a Mouse Model of Ascending Urinary Tract Infection

Enterococcus faecalis is an established nosocomial pathogen, yet the pathogenesis of enterococcal infections, particularly of urinary tract infections (UTIs), remains to be fully elucidated. Fibronectin-binding proteins have been identified as potent adhesins in pathogenic Gram-positive cocci. Here, we characterized EfbA, which is encoded by the enterococcal orthologue of Streptococcus pneumoniae pavA. Similar to PavA, the anchorless EfbA protein was localized to the enterococcal cell outer surface and bound to immobilized human fibronectin. In addition to abrogated EfbA expression, deletion of the efbA gene eliminated EfbA from the cell surface and drastically reduced the enterococcal cell binding to immobilized fibronectin. The ΔefbA deletion mutant was highly attenuated vs wild-type in a murine ascending UTI model, consistent with an increased tropism for the kidney relative to the bladder. These results provide the first evidence that EfbA of E. faecalis plays a role in UTIs, probably contributing to the pathogenesis in this site.

In Vitro Activity and Microbiological Efficacy of Tedizolid (TR-700) against Gram-Positive Clinical Isolates from a Phase 2 Study of Oral Tedizolid Phosphate (TR-701) in Patients with Complicated Skin and Skin Structure Infections

Tedizolid (TR-700, formerly torezolid) is the active moiety of the prodrug tedizolid phosphate (TR-701), a next-generation oxazolidinone, with high potency against Gram-positive species, including methicillin-resistant Staphylococcus aureus (MRSA). A recently completed randomized, double-blind phase 2 trial evaluated 200, 300, or 400 mg of oral tedizolid phosphate once daily for 5 to 7 days in patients with complicated skin and skin structure infections. This report examines the in vitro activity of tedizolid and Zyvox (linezolid) against Gram-positive pathogens isolated at baseline and describes the microbiological and clinical efficacy of tedizolid. Of 196 isolates tested, 81.6% were S. aureus, and of these, 76% were MRSA. The MIC(50) and MIC(90) of tedizolid against both methicillin-susceptible S. aureus (MSSA) and MRSA were 0.25 μg/ml, compared with a MIC(50) of 1 μg/ml and MIC(90) of 2 μg/ml for linezolid. For coagulase-negative staphylococci (n = 7), viridans group streptococci (n = 15), and beta-hemolytic streptococci (n = 3), the MICs ranged from 0.03 to 0.25 μg/ml for tedizolid and from 0.12 to 1 μg/ml for linezolid. The microbiological eradication rates at the test-of-cure visit (7 to 14 days posttreatment) in the microbiologically evaluable population (n = 133) were similar in all treatment groups, with overall eradication rates of 97.7% for all pathogens, 97.9% for MRSA, and 95.7% for MSSA. The clinical cure rates for MRSA and MSSA infections were 96.9% and 95.7%, respectively, across all dose groups. This study confirms the potent in vitro activity of tedizolid against pathogenic Gram-positive cocci, including MRSA, and its 4-fold-greater potency in comparison with linezolid. All dosages of tedizolid phosphate showed excellent microbiological and clinical efficacy against MRSA and MSSA.

Mechanisms of Resistance to Antimicrobial Drugs in Pathogenic Gram-Positive Cocci

Many species of Gram-positive cocci are pathogenic. The most important are staphylococci, streptococci, and enterococci. Widespread usage of antibiotics was the main cause for the appearance and spread of resistance to almost all antimicrobials. The occurrence, mechanisms, and genetic background of resistance to antimicrobial drugs other than beta-lactams and glycopeptides among pathogenic staphylococci, streptococci, and enterococci are discussed in the text. Well-established agents (such as macrolides, lincosamides, streptogramins, aminoglycosides, quinolones, mupirocin, chloramphenicol) as well as new agents (linezolid, daptomycin, quinupristine/dalfopristine, ratapamulin, tigecycline, iclaprim and new generations of quinolones) are considered.

In silico analysis of a family of extracellular polysaccharide deacetylases involved in virulence of pathogenic gram-positive cocci

Background Pathogenic bacteria incessantly evolve mechanisms to resist their host’s innate immunity. One such mechanism is molecular camouflage: the modification of bacterial surface molecules to make them unrecognizable by the host’s immune system or resistant to its effector molecules. Recently, a peptidoglycan deacetylase (PgdA) was discovered in Streptococcus pneumoniae that renders bacterial peptidoglycan resistant to human lysozyme, thus preventing host-mediated cell wall damage [1-3]. In addition, polysaccharide deacetylases with different substrate specificities were identified in other

Structure and Mechanism of the Lincosamide Antibiotic Adenylyltransferase LinB

Lincosamides make up an important class of antibiotics used against a wide range of pathogens, including methicillin-resistant Staphylococcus aureus. Predictably, lincosamide-resistant microorganisms have emerged with antibiotic modification as one of their major resistance strategies. Inactivating enzymes LinB/A catalyze adenylylation of the drug; however, little is known about their mechanistic and structural properties. We determined two X-ray structures of LinB: ternary substrate- and binary product-bound complexes. Structural and kinetic characterization of LinB, mutagenesis, solvent isotope effect, and product inhibition studies are consistent with a mechanism involving direct in-line nucleotidyl transfer. The characterization of LinB enabled its classification as a member of a nucleotidyltransferase superfamily, along with nucleotide polymerases and aminoglycoside nucleotidyltransferases, and this relationship offers further support for the LinB mechanism. The LinB structure provides an evolutionary link to ancient nucleotide polymerases and suggests that, like protein kinases and acetyltransferases, these are proto-resistance elements from which drug resistance can evolve.

Mechanisms of the Resistance and Tolerance to Beta-Lactam and Glycopeptide Antibiotics in Pathogenic Gram-Positive Cocci

Beta-lactams are the most frequently used antimicrobials in combating infections. In the case of gram-positive bacteria resistant to beta-lactams, glycopeptides are the first choice. The occurrence, mechanisms and genetic background of the resistance of pathogenic staphylococci, streptococci and enterococci to beta-lactam and glycopeptide antibiotics were discussed. The resistances to well-established antimicrobials, as well as new agents (ceftobiprole, oritavancin, telavancin, dalbavancin) were taken into consideration in the text.

Inactivation of the srtA gene in Streptococcus gordonii inhibits cell wall anchoring of surface proteins and decreases in vitro and in vivo adhesion.

The srtA gene product, SrtA, has been shown to be required for cell wall anchoring of protein A as well as virulence in the pathogenic bacterium Staphylococcus aureus. There are five major mechanisms for displaying proteins at the surface of gram-positive bacteria (P. Cossart and R. Jonquieres, Proc. Natl. Acad. Sci. USA 97:5013-5015, 2000). However, since many of the known surface proteins of gram-positive bacteria are believed to be exported and anchored via the sortase pathway, it was of interest to determine if srtA plays a similar role in other gram-positive bacteria. To that end, the srtA gene in the human oral commensal organism Streptococcus gordonii was insertionally inactivated. The srtA mutant S. gordonii exhibited a marked reduction in quantity of a specific anchored surface protein. Furthermore, the srtA mutant had reduced binding to immobilized human fibronectin and had a decreased ability to colonize the oral mucosa of mice. Taken together, these results suggest that the activity of SrtA plays an important role in the biology of nonpathogenic as well as pathogenic gram-positive cocci.

Identification of a structural determinant for resistance to beta-lactam antibiotics in Gram-positive bacteria.

Streptococcus pneumoniae is the main causal agent of pathologies that are increasingly resistant to antibiotic treatment. Clinical resistance of S. pneumoniae to beta-lactam antibiotics is linked to multiple mutations of high molecular mass penicillin-binding proteins (H-PBPs), essential enzymes involved in the final steps of bacterial cell wall synthesis. H-PBPs from resistant bacteria have a reduced affinity for beta-lactam and a decreased hydrolytic activity on substrate analogues. In S. pneumoniae, the gene coding for one of these H-PBPs, PBP2x, is located in the cell division cluster (DCW). We present here structural evidence linking multiple beta-lactam resistance to amino acid substitutions in PBP2x within a buried cavity near the catalytic site that contains a structural water molecule. Site-directed mutation of amino acids in contact with this water molecule in the "sensitive" form of PBP2x produces mutants similar, in terms of beta-lactam affinity and substrate hydrolysis, to altered PBP2x produced in resistant clinical isolates. A reverse mutation in a PBP2x variant from a clinically important resistant clone increases the acylation efficiency for beta-lactams and substrate analogues. Furthermore, amino acid residues in contact with the structural water molecule are conserved in the equivalent H-PBPs of pathogenic Gram-positive cocci. We suggest that, probably via a local structural modification, the partial or complete loss of this water molecule reduces the acylation efficiency of PBP2x substrates to a point at which cell wall synthesis still occurs, but the sensitivity to therapeutic concentrations of beta-lactam antibiotics is lost.

Enterococcal superinfection and colonization after therapy with moxalactam, a new broad-spectrum antibiotic.

Brief Reports1 June 1981Enterococcal Superinfection and Colonization After Therapy with Moxalactam, a New Broad-Spectrum AntibioticVICTOR L. YU, M.D.VICTOR L. YU, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-94-6-784 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptMoxalactam is a new broad-spectrum antimicrobial drug that is structurally related to the cephalosporins (1). Its favorable pharmacokinetic properties allow it to be administered at 8-hour intervals (2), and unlike other cephalosporins, it reaches the cerebrospinal fluid in therapeutic concentrations (3). However, its major attraction is its effectiveness in vitro against many bacterial pathogens. It is active against the usual pathogenic gram-positive cocci (streptococci, pneumococci, staphylococci) as well as the Enterobacteriaceae (1, 4). Moreover, it is active in vitro against anaerobes (includingBacteroides fragilis) as well asHaemophilus influenzae(including ampicillin-resistant strains) andPseudomonas aeruginosa(4-6). No other commercially available...

ANTIBIOTIC CONCENTRATIONS IN MIDDLE EAR EFFUSIONS

Penicillin G and oxytetracycline were present in measurable concentrations in effusions taken from the middle ear of patients with acute suppurative otitis media, following an intramuscular injection of either drug from 1 to 3 hours earlier. Fluid taken from the middle ear space of patients with secretory otitis media given similar injections contained quantities of oxytetracycline too low to measure accurately, while penicillin activity was readily measurable and comparable to levels found in patients with acute suppurative otitis media. When the antibiotic concentrations present in these effusions were considered in terms of the accepted in vitro inhibitory concentrations of the common middle ear pathogens, penicillin appeared to be the drug better suited for the management of most acute middle ear bacterial infections. Oxytetracycline, on the basis of its in vitro antibacterial activity and the concentrations achieved in the middle ear fluid, does not appear to be the drug of choice if the pathogen is Strep. pyogenes, D. pneumoniae, or Staph. aureus. A limited number of observations suggests that penicillin, though not the ideal drug, has more promise than oxytetracycline in the management of middle ear infections due to H. influenzae. Preliminary observations suggest that penicillin given by mouth results in concentrations in middle ear effusions adequate to suppress a large proportion of the pathogenic gram-positive cocci that cause middle ear infection. An extensive study of this problem is needed. Other antibiotics should be studied to find an agent that both enters the middle ear in concentrations equal to or in excess of those needed to inhibit H. influenzae in vitro and possesses the activity of penicillin against the common gram-positive pathogens responsible for middle ear infections.

The relationship between drug susceptibility patterns and enzyme patterns in pathogenic gram-positive cocci

Classification on the basis of carbon requirements, in the form of substrates in the Krebs tricarboxylic acid cycle, placed the pathogenic gram-positive cocci (Strep. pyogenes [Lancefield A], enterococcus and pneumococcus) in group 1, and Staph. aureus in group 2. Of one hundred eighty-nine clinical strains of staphylococci, 70.4 per cent were urease-positive and 29.6 per cent were urease-negative by cultural methods. Sonic lysates of urease-positive staphylococcus were highly active in comparison to cultures of intact organisms. There was no clear-cut correlation between drug susceptibility and phage sensitivity in the staphylococci studied. The sonic lysates of non-urease-producing Strep, pyogenes (Lancefield A) and enterococcus showed potent urease activity. Pneumococcus, which is a non-urease-producer, also exhibited urease activity in sonic lysates. Drug susceptibility did not correlate with urease activity in pathogenic gram-positive cocci. This was in contrast to the findings with coliform organisms.