The distribution of isoprenoid quinones in streptococci of serological groups D and N.

The isoprenoid quinone contents of streptococci of serological groups D and N were investigated. Streptococcus faecalis, S. faecalis subsp. liquefaciens and S. faecalis subsp. zymogenes strains contained demethylmenaquinones with nine isoprene units as their major isoprenologues. Menaquinones with eight isoprene units predominated in S. faecium subsp. casseliflavus and S. faecium subsp. mobilis whereas menaquinones with nine isoprene units constituted the major components in strains of S. cremoris, S. cremoris subsp. alactosus, S. lactis and S. lactis subsp. diacetylactis. Strains of S. avium, S. bovis, S. durans, S. equinus, S. faecium, S. raffinolactis and S. suis contained neither menaquinones nor ubiquinones. The isoprenoid quinone data correlate well with other kinds of data on these organisms and are of value in the classification of these bacteria.     

Enumeration and speciation of group D streptococci from above and below a sewer outfall,their susceptibilities to six antibiotics and a comparison with clinical isolates

Isolates of group D streptococci from above and below a sewer outfall and a series of clinical isolates have been speciated to sub-species level. From below the sewer outfall, Streptococcus faecalis var. faecalis predominates whereas above the outfall, S. faecium var. casseliflavus predominates. S. faecalis var. faecalis, S. faecalis var. liquefaciens and S. faecalis var. zymogenes were the predominant sub-species in the clinical isolates where S. faecium var. casseliflavus was virtually absent. S. faecalis var. liquefaciens and S. faecalis var. zymogenes were uncommon in the environmental isolates. S. faecium and S. durans were more abundant in the environmental than in the clinical isolates. The use of group D streptococci as indicators of faecal pollution would seem more suited to higher, rather than lower, levels of pollution. A statistically significant increase in resistance to antibiotics (ampicillin, penicillin, streptomycin, gentamicin, erythromycin and tetracycline) was seen in isolates from below the outfall compared with those from above and a further significant increase was seen in the clinical isolates compared with the former. Resistance to tetracycline was most common and ampicillin was the only antibiotic tested to which no resistance was detected. Multiple antibiotic resistance was rare in the environmental isolates. Even in moderately polluted water, there is not a large pool of antibiotic resistance.     

In-vitro Comparison of Erythromycin,Lincomycin, and Clindamycin

The in-vitro antibacterial activities of erythromycin, lincomycin, and clindamycin, a new derivative of lincomycin, were compared. Clindamycin was always more active than lincomycin, and was either as active as erythromycin or more so against betahaemolytic streptococci, Streptococcus viridans, Str. pneumoniae, and erythromycin-sensitive Staphylococcus aureus. It was also fully active against most erythromycin-resistant strains of Staph. aureus. On the other hand, it was somewhat less active than erythromycin against Haemophilus influenzae and considerably less active than erythromycin against Str. faecalis and Neisseria gonorrhoeae.Clinical trials seem to be justified in infections with sensitive organisms for which erythromycin might have been indicated.     

Distribution of cytochrome-like respiration in streptococci.

The electron transport systems of 134 strains of streptococci were studied after aerobic growth on glucose in the presence of haematin, by examining the inhibition of electron transport as well as the cellular site of NADH oxidation. Each strain was placed into one of three possible groups: cytochrome-like NADH oxidase; flavin-like NADH oxidase; or no NADH oxidase. Most (88%) of the strains of Streptococcus faecalis and its variants liquefaciens and zymogenes and a few strains of S. lactis and its variant diacetylactis contained cytochrome-like respiratory systems. Other streptococci including S. faecium fell into one of the other groups but did not contain cytochrome-like NADH oxidases.     

Antibiotic sensitivity of nonfermenting gram-negative bacteria

Antibiotic resistance of 132 strains of nonfermenting gram-negative bacteria (NGNB) was studied. 43, 20, 17, 14 and 12 of them belonged to Acinetobacter calcoaceticus (anitratus and lwoffi), Pseudomonas cepacia, Alcaligenes faecalis, P. stutzeri and P. maltophilia, respectively. With rare exceptions all the strains were resistant to benzylpenicillin, oxacillin, lincomycin, ampicillin and cephaloridine. Sensitivity to the other antibiotics varied within wide ranges. Amikacin (94.3 per cent) and tobramycin (90.8 per cent), as well as polymyxin, rifampicin and gentamicin (71.7-66.9 per cent) had the highest effect. The majority of the antibiotics had higher activity (p less than 0.01) against the tested NGNB as compared to their activity against P. aeruginosa. Antibioticograms of every of the tested species of NGNB revealed that P. cepacia and P. stutzeri were the most resistant species. The biovars of Acinetobacter varied in their antibiotic resistance: A. subsp. lwoffi was more sensitive to the majority of the antibiotics though some of them, i.e. doxycycline, carbenicillin, and polymyxin were more active against A. subsp. anitratus.     

Bacteriolysis and Inhibition of Gram-Positive Bacteria by Components of Streptococcus zymogenes Lysin

The ability of the A and L components of Streptococcus zymogenes lysin to cause lysis or to inhibit growth of a variety of gram-positive bacteria has been examined. Frank lysis of some, but not all, strains of S. faecalis, S. faecium, and S. liquefaciens by L component alone was demonstrated. None of the strains of these species was lysed by A component alone. S. durans was not lysed by either component. Inhibition of growth of all enterococcal strains by both A substance-producing and L substance-producing mutants of S. zymogenes was also demonstrated. However, inhibition by the A substance producer was markedly less than by the L substance producer. Inhibition of the growth of a number of other gram-positive genera by both A and L mutants was also noted.     

Studies on faecal streptococci in the river Tigris

Six hundred water samples collected from the river Tigris at Mosul City were investigated for faecal streptococci. Human faecal streptococci were predominant, and animal faecal streptococci were also detected. Eight species and varieties were identified, viz Streptococcus faecalis, atypical Streptococcus faecalis, Streptococcus bovis, Streptococcus equinus, Streptococcus faecalis var. liquefaciens, Streptococcus faecalis var. zymogenes, Streptococcus durans and Streptococcus faecium. The incidence of these species and varieties were 43.32%, 13.18%, 11.47%, 11.30%, 9.76%, 5.30%, 3.76% and 1.88%, respectively.     

Species Differentiation of Faecal and Nonfaecal Enterococci

A number of the cultural and biochemical criteria of the more resistant enterococci were used collectively to speciate 2,477 enterooocci strains isolated from water, soil, vegetation, sewage and human and animal faeces into 2 major groups: Streptococcus faecalis and S. faecium. Streptococcus faecalis was found to predominate in the human and poultry gut, S. faecium predominated in the livestock gut, while both organisms were about equally demonstrated in water, soil, vegetation and sewage samples.     

Antibiotic resistance dynamics and isolation rate of staphylococci and enterococci from patients of reconstructive surgery units

The dynamics of isolation of staphylococci and enterococci from clinical material of patients and their antibiotic susceptibility within a 5-year period (2005-2009) was analysed. 5990 isolates were tested: 1250 isolates of Staphylococcus aureus, 3268 isolates of S. epidermidis, 1005 isolates of Enterococcus faecalis and 467 isolates of E. faecium. Grampositive infections were shown to be prevailing within the last 2-3 years, the nosocomial epidermal staphylococci more and more replacing S. aureus (the ratio of S. epidermidis and S. aureus in 2009 was 3.3). The isolation rate of E. faecalis significantly increased (by 3.5 times) and the ratio of E. faecalis and E. faecium in 2009 was 4.3. The microflora composition with respect to the isolation source was analysed and its clinical significance was estimated. The study of the antibiotic susceptibility showed that oxacillin had its own specific niche, while antibiotics active against resistant grampositive cocci, such as rifampicin, fusidic acid, fluoroquinolones (moxifloxacin), cefoxitin, as well as amoxicillin/clavulane in infections due to E. faecalis, might be considered as the drugs of choice. In the treatment of nosocomial infections, when the etiological role of MRSA or VRE is suspected or confirmed, the complex therapy should obligatory include the most active antibiotics (vancomycin or linezolid among them).     

Peptidoglycan composition and taxonomy of group D, E, and H streptococci, and Streptococcus mutans

The qualitative and quantitative composition of the peptidoglycan from the cell wall of groups D, E, and H streptococci, and Streptococcus mutans, was determined. In group D, S. faecalis and the closely related species S. liquefaciens and S. zymogenes were separated from S. faecium and the closely related species S. durans on the basis of their peptidoglycan composition. A relationship among S. bovis, S. equinus, and some strains of S. mutans was indicated by the presence in each of a similar peptidoglycan containing threonine. Threonine was released from the S. mutans polymer as a threonine-lysine dipeptide. Hydrolysis of the dipeptide at 100 C for 24 hr in 6 n HC1 was required to break the peptide bond. Motile group D streptococci possessed a peptidoglycan of the same composition as S. faecium. Group E and H strains were also similar in the composition of their peptidoglycan. The results demonstrate that peptidoglycan composition can be used to (i) aid in the division of members of an immunological group into subgroups, and (ii) indicate a relationship between members of the same genus which are not related on an immunological basis.     

Effect of Lactic Acid Bacteria on Growth of Staphylococcus aureus

Cultures of lactic acid bacteria, mostly from foods, were tested for their effect on the growth of Staphylococcus aureus in Trypticase Soy Broth (BBL). Some of the effectors, e.g., Streptococcus faecalis, S. faecium, Lactobacillus lactis, L. brevis, and Leuconostoc mesenteroides, stimulated growth of S. aureus during early hours of growth, especially at higher temperatures of incubation, but most cultures were inhibitory, and some (S. faecium and L. mesenteroides) were even killing by the time of attainment of the maximal phase of growth of the Staphylococcus. Low-temperature meat lactobacilli and Leuconostoc dextranicum inhibited S. aureus at 10, 15, 20, and 25 C throughout its growth. Streptococcus faecalis var. liquefaciens inhibited at these temperatures and at 30 and 37 C, as well. When the ratio of effectors to staphylococci in the inoculum was 100:1, the three enterococci, the meat Lactobacillus, and L. dextranicum prevented the attainment of 5 x 10(6) staphylococci per milliliter at 15 C, and all but the meat Lactobacillus did so at 22 C. A ratio of 1:1 accomplished similar results at 15 C, except that S. aureus was only delayed for 12 hr by S. faecalis. A ratio of 1:100 usually was ineffective. In general, the more effector bacteria there were in the inoculum, the greater was the overall inhibition (or stimulation) of S. aureus. Inhibition was most effective at 10 or 15 C, less so at 20 or 25 C, and least at 30 or 37 C, whereas stimulation during early growth was greater at the higher temperatures. Results with different strains of the effectors and with two strains of S. aureus were similar, for the most part.     

Identification of a streptococcal penicillin-binding protein that reacts very slowly with penicillin.

Penicillin-binding protein (PBP) 5 of Streptococcus faecium ATCC 9790 has an unusually low affinity for penicillin (50% binding occurred at a penicillin level of 8 micrograms/ml after 60 min of incubation, and the protein only became labeled after 20 min of incubation with high concentrations of radioactive penicillin). PBPs with similar properties are carried by strains of Streptococcus durans, Streptococcus faecalis, and Streptococcus lactis but not by strains of groups A, B, C, and G streptococci or Streptococcus pneumoniae. The strains carrying the slow-reacting PBP demonstrated a sensitivity to penicillin that was several hundred times lower than that of strains not carrying it. Spontaneous mutants with minimal inhibitory concentrations of penicillin of 20, 40, and 80 micrograms/ml were isolated from S. faecium ATCC 9790. They all showed a dramatic increase in the amount of slow-reacting PBP produced. Mutants with increased penicillin resistance were also isolated from wild-type strains of S. durans, S. faecalis, and S. faecium. All of them carried a greater amount of the slow-reacting PBP than that carried by the parent. Finally, it was found that resistant S. faecium ATCC 9790 mutants grew normally in the presence of penicillin concentrations that were far above that saturating all PBPs except PBP 5. Cell growth was, on the contrary, inhibited by a penicillin concentration that saturated the slow-reacting PBP by 90%. This penicillin dose was equal to the minimal inhibitory concentration.     

Reducing activity and differential thermal analysis of enterococci

The reducing activity of 100 Streptococcus faecalis strains, 100 Streptococcus faecium strains and 100 enterococcal strains were studied by the quantitative method. The study revealed that all mobile enterococci, in contrast to S. faecium, reduce 2,3,5-triphenyltetrazolium chloride with the formation of triphenylformasan. Differential thermal analysis also indicated that S. faecalis, S. faecium and mobile enterococci had thermograms with definite mathematical characteristics and could be best differentiated by the indices of their form and the size of S3 areas. The quantitative methods of the investigation of reducing activity and differential thermal analysis can be used for the differentiation of enterococcal species. Mobile enterococci have definite characteristics allowing one to sharply differentiate them from S. faecium and S. faecalis.     

Comparative survival of antibiotic-resistant and -sensitive fecal indicator bacteria in estuarine water.

The survival of antibiotic-resistant and -sensitive strains of Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Streptococcus equinus, and two environmental isolates, AP17 and AQ62, was examined in estuarine water. Each strain was rendered resistant to a combination of two antibiotics by serial passage in increasing concentrations of antibiotics. Cultures were incubated in filter-sterilized estuarine water for up to 7 days. Recovery was assessed by examining colony-forming ability on media with and without antibiotics. None of the antibiotic-resistant forms survived longer than its antibiotic-sensitive counterpart in estuarine water. Three of the resistant strains died off more rapidly than the antibiotic-sensitive wild type. Survival of the test bacteria in estuarine water was as follows: sensitive and resistant AQ62, resistant Escherichia coli less than sensitive Escherichia coli less than resistant AP17 less than resistant Enterococcus faecium less than sensitive AP17, sensitive and resistant S. equinus less than sensitive and resistant Enterococcus faecalis, sensitive Enterococcus faecium. The results supported the suggestion that fecal entercocci may serve as better indicators of fecal pollution than Escherichia coli in marine ecosystems. Moreover, the results indicated that the use of antibiotic-resistant mutants to follow the fate of bacteria in the environment is inappropriate without adequate studies to ensure that resistant and wild-type strains react similarly to environmental stressors.     

Population biology of Gram-positive pathogens: high-risk clones for dissemination of antibiotic resistance

Infections caused by multiresistant Gram-positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae and S. pyogenes, and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquisition of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review, we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy.     

The effect of growth-promoting antibiotics on the faecal enterococci of healthy young chickens

Small groups of chickens were given feed containing either avoparcin, nitrovin, vir-giniamycin or zinc bacitracin from the day of their purchase as day-olds. Differences between the birds receiving growth promoters and the untreated controls were observed during the last third of the 23 d survey period. The enterococcal population of the 'dosed' birds contained a greater proportion of Enterococcus faecium than did that of the control birds while the converse was true for Ent. gallinarum . This apparent selection of Ent. faecium by the growth-promoting antibiotics had an influence on the incidence of resistance to therapeutic antibiotics among the enterococcal population as a whole. This was because this species was generally more resistant than Ent. gallinarum to cephalothin, the MLS antibiotics (erythromycin, lincomycin and tylosin) and tetracycline.     

Enterococci in Insects

Enterococci were obtained from 213 of 403 insects cultured during a 14-month period, in numbers from 10(3) to 3 x 10(7)/g of insect. Insects were taken only from nonurban, wild, and cultivated fields and woods. In species of insects carrying them, enterococci were not always present in every individual cultured, and often more than one species of enterococcus occurred within a species. Enterococci were obtained from certain insects taken in the field during the dormant season, suggesting their role as overwintering agents. They were generally present in species feeding on nectar, succulent plant parts, and on and ir forest litter, but not from insects feeding on less succulent leaves and stems. Streptococcus faecalis was recovered from 32%, Streptococcus faecium from 22.4%, and Streptococcus faecium var. casseliflavus from 43.5% of members of the 37 taxa of insects. S. faecalis and S. faecium var. casseliflavus exhibit a high percent of conformity to the properties published for them. The heterogeneity in properties of S. faecium is similar to that found for the species taken from plants. Many fail to grow in broth at 45 C or in broth containing 6.5% NaCl; 50% of the cultures ferment both melezitose and melibiose, and a few ferment neither sugar. The remainder ferment melibiose only. Failure to reduce methylene blue in milk by S. faecalis and S. faecium is correlated with the inability to ferment lactose. More than 93% of the cultures of S. faecalis digest casein in milk from the top downward, following the production of a soft, flowing curd. Because this property is not characteristic of S. faecalis taken from humans, the reaction in litmus milk is suggested as a means of differentiation between cultures of remote and innocent origin in nature and recent, human pollution.     

Activities of Arginine Dihydrolase and Phosphatase in Streptococcus faecalis and Streptococcus faecium

Strains of Streptococcus faecalis and S. faecium are known to produce ammonia from arginine, but only S. faecalis couples the adenosine triphosphate (ATP) produced through the arginine dihydrolase pathway to growth processes. The specific activities of the arginine dihydrolase enzymes were found to be much lower in S. faecium (0.01 to 0.10) than in S. faecalis (0.24 to 1.60). Phosphatase activities in both strains were similar (up to 0.11), but equaled or exceeded the activities of the arginine dihydrolase enzymes in S. faecium. The failure of S. faecium to show increased growth in arginine media is explained on the basis of low activities of the arginine dihydrolase enzymes coupled with sufficient phosphatase activity to negate any benefit from ATP formed.     

Incidence of virulence factors and antibiotic resistance among Enterococci isolated from food

The incidence of virulence factors among 48 Enterococcus faecium and 47 Enterococcus faecalis strains from foods and their antibiotic susceptibility were investigated. No strain was resistant to all antibiotics, and for some strains, multiple resistances were observed. Of E. faecium strains, 10.4% were positive for one or more virulence determinants, compared to 78.7% of E. faecalis strains. Strains exhibiting virulence traits were not necessarily positive for all traits; thus, the incidence of virulence factors may be considered to be strain specific.     

Sensitivity of the wound microflora of oncological patients to some new antibiotics]

Sensitivity of the microflora of the oncological patients' wounds to the new antibiotics, such as gentamicin, kanamycin, oxacillin, ampicillin and lincomycin was studied with the help of the disc method. The discs with the above antibiotics were prepared under laboratory conditions in accordance with the respective instructions in the WHO. Sensitivity of 429 bacterial cultures, including 98 cultures of pathogenic staphylocci, 45 cultures of Enterococci, 43 hemolytic streptococci, 143 cultures of Escherichia, 50 cultures of Ps. aeruginosa and 50 cultures of Proteus was determined. The studies showed that gentamicin was the most active antibiotic aganist all the microbial species isolated from the surgical and other wounds of oncological patients. It may be used in treatment of the infections caused by association of the microbes belonging to different species, as well as in treatment of purulent processes before elucidating their etiology, 16.7 per cent of the Enterococcal isolates were resistant to gentamicin. Monomycin, kanamycin, oxacillin, lincomycin and macrolide antibiotics at present are sufficiently active against pathogenic staphylococci and hemolytic streptococci.