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PubMed1983

Induced changes in the surface of Neisseria gonorrhoeae.

Growth of Neisseria gonorrhoeae strain F62 on medium containing pyruvate and a high ratio of cysteine to cystine resulted in functional and structural changes that are consistent with phenotypic changes in lipopolysaccharide. Both transparent (O-) and moderately opaque (O+) variants became more sensitive to killing by normal human serum and resistant to killing by pyocin G, a bacteriocin from Pseudomonas aeruginosa. Electrophoresis of outer membranes in the presence of sodium dodecyl sulfate demonstrated differences also dependent upon the growth medium. When gels were treated with periodic acid and stained with silver, lanes containing outer membranes obtained after growth in the modified medium demonstrated two bands in addition to those independent of the growth medium. The enhancement of these additional bands by periodate treatment indicated that they represent material containing carbohydrate. The mechanism by which the changes in the growth medium affected the surface of N. gonorrhoeae is not known; however, the changes demonstrated by electrophoresis were dependent upon either the high concentration of cysteine or the high ratio of cysteine to cystine.

Blood Bactericidal Activity↗
PubMed1980

In vitro evaluation of new penicillins and cephalosporins upon P. aeruginosa and their interaction with mecillinam.

The in vitro activity of the new semisynthetic ureidopenicillins azlocillin (AZ) and mezlocillin (MZ), and of the new cephalosporin cefsulodin (CEF) were determined against 50 carbenicillin-sensitive (CARs) and 50 carbenicillin-resistant (CARr) P. aeruginosa clinical isolates. In the CARs group the most active antibiotics are AZ and CEF with MICs between 0.5 and 8 microgram/ml. Ticarcillin (TIC) and MZ showed more activity than CAR with MICs from 2 to 32 mu/ml. In this group there is a predominance of pyocine-type groups 1 and 3. In the CARr group, AZ is the most active antibiotic at low concentrations. At 64 microgram/ml of CEF, 72% of strains are inhibited as compared to 70% with AZ, 62% with MZ and 50% with TIC. In this group there is predominance of non-typeable strains. Interaction with mecillinam (MEC) and these antibiotics was studied on three different culture media (MH, NIH and DST). There were few cases of synergism with MEC and TIC combinations, mostly on DST medium. No appreciable synergism was found with other combinations of antibiotics.

Amdinocillin↗
PubMed1978

Induction of bacteriolytic enzyme from pyocinogenic Pseudomonas aeruginosa and its enzymatic properties.

Mitomycin C induced a pyocinogenic Pseudomonas aeruginosa P15 to produce a bacteriolytic enzyme, PR1-lysozyme, together with pyocin R1. No significant accumulation of the enzyme was observed inside the induced cells. The enzyme was partially purified by acrinol treatment and Amberlie CG-50 column chromatography. The mode of action of the enzyme on the host bacterial cells as well as on Micrococcus lysodeikticus cells or peptidoglycan isolated from Salmonella typhimurium, was compared with that of hen egg-white lysozyme or phage lambda-lysozyme. It is suggested that PR1-lysozyme should be classified as a glycosidase, rather than an amidase or an endopeptidase.

Bacteriolysis↗
PubMed1992

[Studies on the serotyping and pyocintyping of Pseudomonas aeruginosa].

Pseudomonas aeruginosa (118 strains) from Xian were typed by 12 groups O-serum and revised pyocin typing method Results indicated that VI, I, III were major serotypes, VI type were mainly from trauma infected, I type mainly from respiration system infected. Pyocintype were mainly I and UT types. Pyocintype I were mainly 1/c and 1/x subtypes. 85.7% of 1/c subtypes were serotype VI, 84.4% of 1/x subtypes were serotype I.

Burns↗
PubMed1983

ABO blood group and susceptibility to gonococcal infection. I. Factors affecting phagocytosis of Neisseria gonorrhoeae.

The effect of opsonization of Neisseria gonorrhoeae by isohaemagglutinins from normal serum on attachment to human polymorphonuclear leukocytes (PMN) was investigated. No significant differences between sera from blood groups O, A, B or AB were found. Differences in attachment of gonococci were related to differences in lipopolysaccharide detected by sensitivity to R-type pyocines of Pseudomonas aeruginosa. Non-pilate variants of each test strain markedly stimulated nitroblue tetrazolium (NBT) reduction in PMN, but their pilate variants were essentially inactive in the NBT test.

ABO Blood-Group System↗
PubMedDate not supplied

[Bacteriocins as cytotoxic agents in experimental neoplasms: considerations on the role of possible contaminants].

In most recent papers some Authors have demonstrated that several bacteriocins are able to markedly inhibit the division of various neoplastic mammalian cell lines; also in vivo the inhibition of tumor growth or even regression relative to controls are statistically significant. Since such preparations are "crude" and it's possible that contaminating agents may represent a possible source of variability in the results, mostly in vivo; we have examined a preparation of Pyocin employed in this study for the possible endotoxin contamination using the Limulus assay. Such test was positive in triplicate and semiquantitative determination has shown and endotoxin amount of 5 to 10 microgram/ml. This level is, in vitro, not anough to give cytotoxic effect, but in vivo is able to influence experimental results. In addition, since some bacteriocins and enterotoxins are produced under exactly identical conditions, there is this a possibility that the enterotoxin are coproduced in these preparations and are causing some of the cytotoxic effects on experimental tumors. A more complete separation and purification of preparations will be required before definitive comments.

Animals↗
PubMed1975

Epidemiological markers for Pseudomonas aeruginosa. 6. Relationship between concomitant non-mucoid and mucoid strains from the respiratory tract in cystic fibrosis.

The simultaneously occurring mucoid (M) and non-mucoid (NM) variants of Pseudomonas aeruginosa frequently observed in cultures from the respiratory tract of chronically infected cystic fibrosis patients have been studied. M cultures in vitro were unstable and easily dissociated NM colonies. In a large proportion of the cases, M and NM variants occurring simultaneously in cultures from one and the same clinical specimen were of the same pyocine type, phage type, and serogroup. In some remaining cases there were small differences between the M and NM variants such that identity between the variants from one and the same specimen was possible, although not definite. The NM dissociants from M strains were of the same type as the M variant. The possible role of cross-infection and the interaction of bacteria and host response factors continuously tending to select the unstable M variant in vivo are discussed.

Adolescent↗
PubMed1996

A preliminary study of fingerprinting of Pseudomonas aeruginosa by whole cell protein analysis by SDS-PAGE.

Forty two strains of Pseudomonas aeruginosa isolated from bronchoalveolar lavage fluid from intubated patients admitted to the Intensive care unit in AIIMS between December 1993 to June 1994 were included in the study. After obtaining typical biochemical profile, antimicrobial susceptibility was performed against ceftazidime, amikacin, gentamicin, ampicillin, cefotaxime and ciprofloxacin. Pyocin typing of these 42 strains was performed by scrape and streak method using 22 indicator strains. Forty strains could be typed showing excellent discrimination but on repeated testing the group designation changed indicating that the system had low reproducibility. SDS-PAGE of whole cell protein profile indicated the presence of 45 protein bands of different molecular weights, individual isolates had 37 to 42 protein band ranging in molecular weight from 340 kDa to 14.3 kDa. On the basis of Dice index of similarity the strains could be grouped into 20 types. Since all strains could be typed, the system has adequate typability. Similar results were obtained on repeated testing indicating good reproducibility.

Bacterial Proteins↗
PubMed1976

Bacterial proteinaceous products (bacteriocins) as cytotoxic agents of neoplasia.

Several bacteriocins, bacterial proteinaceous antibiotics, are shown to markedly inhibit the division of various established (neoplastic) mammalian cell lines. The bacteriocins tested originated from Escherichia coli, Pseudomonas aeruginosa, Vibrio cholerae, and Vibrio eltor. Using exponentially growing L60T mouse fibroblasts, the inhibitory effect was concentration dependent, and a growth inhibitory unit, equivalent to cytotoxic index 50, was established. Expression of toxicity as a function of duration of exposure to pyocin required 3 to 4 hr. DNA synthesis was inhibited and reflected the effects on growth inhibition. Maximal sensitivity to the bacteriocin was observed prior to mitosis in the G2 phase of the cell cycle.

Antineoplastic Agents↗
PubMed1998

Study of Pseudomonas aeruginosa causing ventilator associated pneumonia.

Ps. aeruginosa is a frequent and prominent cause of nosocomial pneumonia especially in persons on assisted ventilation in the intensive care units. In a year long surveillance of ventilator associated pneumonia (VAP) we isolated 42 strains from broncho alveolar lavage samples collected and processed from 102 patients. By pyocin typing 40 of the 42 strains could be typed into 39 types but this designation changed each time the test was repeated. SDS-PAGE analysis of the whole cell proteins grouped the 42 strains of Ps. aeruginosa into 20 groups. After ribotyping, using an 18 mer DIG labelled oligonucleotide to the conserved region of 16S rRNA gene, the strains were designated into 18 types. The major type contained 8 isolates, but there was no clustering of isolates, indicating that each infecting strain was acquired separately and not from a common source. It would, therefore, appear that cross infection with a single clone was not the predominant mode of Ps. aeruginosa infection causing VAP in our ICU.

Cross Infection↗
PubMed1996

Identification of putative active-site residues in the DNase domain of colicin E9 by random mutagenesis.

We have used random mutagenesis to identify putative active-site residues in the C-terminal cytotoxic endonuclease domain of the bacterial toxin colicin E9. Six single-site mutations in the DNase domain were isolated which destroyed the toxic action of the colicin. DNA sequencing identified the mutations as Gly460Asp, Arg544Gly, Glu548Gly, Thr571Ile, His575Tyr and His579Tyr. All six wild-type residues are highly conserved in the DNase domains of both the E group colicins and the closely related pyocins. Site-directed mutagenesis was then used to substitute the wild-type amino acid residue at each of these positions for an alanine residue in order to distinguish important from unimportant sites. Two of the six alanine-mutant colicins (Gly460Ala and His579Ala) exhibited significant in vivo activity, unlike the original mutation of these residues, and were therefore not characterised further. The Thr571Ala mutant colicin, although not inactive, was significantly less active than the control. The other three alanine mutants (Arg544Ala, Glu548Ala and His575Ala remained completely inactive in the in vivo tests. Each 15 kDa alanine-mutant DNase domain was overexpressed and purified using a tandem-expression strategy which relies on the enzyme being able to bind to the natural inhibitor, Im9. Tryptophan emission spectra of the alanine mutants showed significant alterations in the emission maxima of all but the His575Ala mutant, suggesting changes in the tertiary structure of these mutant proteins. Activity measurements, using the spectrophotometric Kunitz assay, indicated that the Thr571Ala mutant was partially active as an endonuclease but the remaining alanine mutants were all completely inactive. All four mutant proteins, however, retained their ability to bind DNA in a gel shift assay, suggesting the mutations affect catalytic rather than substrate-binding residues. Searching the sequence databases for possible homology to other DNA-binding proteins revealed a significant match between residues 464 to 487 of the E9 DNase domain and helix IV of the POU domain of eukaryotic transcription factors.

Alanine↗
PubMed1986

Prevalence of protease and elastase production by clinical isolates of Pseudomonas aeruginosa in relation to aeruginocine typing patterns.

Sixty six consecutive P. aeruginosa isolates from heterogeneous clinical specimens were subjected to aeruginocine (pyocine) typing and assayed for in vitro protease and elastase production by a simple and reproducible qualitative test. The 45.4% of the clinical isolates were found to be both protease and elastase (P + E +) producers; 40.9% were only protease producers (P + E -) and 13.6% were non producers (P - E -). Aeruginocine code 7777 strains were found to be predominant among P + E + and P + E - types, as 48.2% and 51.7% isolates belonged to the types, respectively, suggesting thereby the virulence of this aeruginocine type in P. aeruginosa infections and the possible association of protease and elastase production with aeruginocine production.

Bacteriophage Typing↗
PubMed1986

Antibiotic susceptibility of clinical isolates of Pseudomonas aeruginosa.

Three hundred and twenty two clinical isolates of Pseudomonas aeruginosa collected in Morelia, México, were analyzed for in vitro susceptibility to five antibiotics by agar dilution tests. Antibiotic resistance was shown by 50% of total isolates. Frequencies of resistance were: streptomycin, 47%; gentamicin, 13%; tobramycin, 8%; and carbenicillin, 7%; no amikacin resistance was found. The more common resistance patterns were streptomycin, gentamicin-streptomycin, and tobramycin-gentamicin-streptomycin. Resistance to either tobramycin, gentamicin or carbenicillin was found mainly in pyocin type 10 isolates. The proportion of antibiotic resistant isolates ranged from 37 to 75% in four hospitals, and amounted 24% in three clinical laboratories.

Anti-Bacterial Agents↗
PubMedDate not supplied

Qualitative and quantitative microbiological analysis of sputa of 102 patients with cystic fibrosis.

A microbiological analysis of 102 patients suffering from cystic fibrosis was conducted over a 22 month period. 20 microbial species with the following incidence were identified: Pseudomonas aeruginosa: 83.4%; Candida albicans: 29.4%; Staphylococcus aureus: 24.5%; Staphylococcus epidermidis: 11.8%; Haemophilus influenzae: 11.8%; Streptococcus pneumoniae; 6.9%; Pseudomonas maltophilia: 6.8%; Aspergillus fumigatus: 5.9%. Other species were present in less than 5% of the patients. In the majority of specimens with P. aeruginosa, more than one type (up to six) was detectable. These strains were identical in colony appearance, O-serotype and pyocin-type. Quantitative analysis revealed concentrations of colony-forming units of 10(7) to 10(9) for P. aeruginosa, 10(6) to 10(8) for P. maltophilia, 10(4) to 10(7) for S. aureus, 10(4) to 10(6) for S. epidermidis and 10(4) to 10(7) for C. albicans in the majority of specimens. Significant differences were observed in the time periods during which the pathogens persisted in the patients. Maximum persistence was observed for P. aeruginosa. P. maltophilia and A. fumigatus had about similar persistence rates, which were lower than those for P. aeruginosa but above those for S. aureus and H. influenzae. S. epidermidis was eliminated within shorter periods than S. aureus. C. albicans, although the second most frequent microorganism identified, showed a very low persistence rate. The microbiological analysis confirms results from other research centers (high incidence of P. aeruginosa), but reveals significant regional differences as well (Pseudomonas cepacia not detectable, higher incidence of P. maltophilia and C. albicans). This underlines the necessity for detailed qualitative and quantitative microbiological analysis of sputa from cystic fibrosis patients as a prerequisite for rational analysis of etiological, epidemiological and therapeutical aspects of cystic fibrosis.

Adolescent↗
PubMed1995

Emergence of resistance to beta-lactam agents in Pseudomonas aeruginosa with group I beta-lactamases in Spain.

The contribution of induction and stable derepression of chromosomal class I beta-lactamases to beta-lactam antibiotic resistance was studied in clinical isolates of Pseudomonas aeruginosa collected from patients treated with beta-lactam antibiotics. Multiple isolates from the same patient were characterized by O-serotyping as a primary screen, combined with pyocin typing. Sonicated extracts of cells were assayed for chromosomal and plasmid-mediated beta-lactamases by isoelectric focusing and cloxacillin inhibition studies. The specific beta-lactamase activity, basal and induced, with cefoxitin was determined to differentiate strains with inducible or derepressed production of the enzyme. Beta-lactamase induction was performed in each strain against the beta-lactam agents used in the therapy of each patient. The observations showed that induction against older penicillins such as penicillin, amoxicillin, and amoxicillin/clavulanate resulted in a moderate to strong increase in beta-lactamase activity, whereas the results obtained with first-generation cephalosporins varied with the beta-lactam agent tested. Third-generation cephalosporins were weak inducers of beta-lactamases, and their use as therapy preceded the appearance of strains that produce chromosomal group I beta-lactamases constitutively. These strains showed a remarkable reduction in sensitivity to ureidopenicillins, carboxipenicillins, third-generation cephalosporins, and monobactams, but not to carbapenems.

Anti-Bacterial Agents↗
PubMed1995

Use of pulsed-field gel electrophoresis as an epidemiologic tool during an outbreak of Pseudomonas aeruginosa lung infections in an intensive care unit.

OBJECTIVE: A retrospective study was performed to evaluate the use of DNA polymorphism analysis by pulsed-field gel electrophoresis (PFGE) in assessing the rate of exogenous contamination during an outbreak of Pseudomonas aeruginosa lung infections in an intensive care unit ICU. Another goal was to determine the risk factors, involved in the outbreak. DESIGN: Rectal swabs and tracheal secretions were cultured from all patients upon admission and thereafter once a week throughout their stay in the ICU. Resistance patterns were determined in all P. aeruginosa isolates. We determined the serotypes, pyocin types, plasmid profiles and total DNA macrorestriction patterns for isolates. The restriction fragment length polymorphism (RFLP) of Dra I total DNA digest was studied by PFGE. A retrospective case-control study was performed to determine the risk factors for P. aeruginosa bronchopulmonary colonization. SETTING: The study was carried out in the medical ICU of Besancon University Hospital (France). RESULTS: The typability, stability and reproducibility of phenotypic markers were not completely satisfactory. Only the RFLP profile satisfied all the criteria for a good typing technique. In four of the 17 patients, P. aeruginosa strains with the same DNA pattern were found. Among the previously reported risk factors for hospital-acquired bronchopulmonary infections, only invasive procedures were determined by multivariate analysis to be significant in our study group. The oropharynx and the bronchial tract are the most likely endogenous sources. CONCLUSION: PFGE-RFLP is a valuable tool for the epidemiologic study of P. aeruginosa. This typing method revealed that exogenous contamination is not always the major source of P. aeruginosa lung infections in mechanically ventilated patients in ICUs.

Analysis of Variance↗
PubMed1993

Exogenous or endogenous reservoirs of nosocomial Pseudomonas aeruginosa and Staphylococcus aureus infections in a surgical intensive care unit.

OBJECTIVE: A 4 month prospective study was performed to assess the incidence and routes of endogenous or exogenous colonization and nosocomial infection caused by Staphylococcus aureus and Pseudomonas aeruginosa in surgical critically ill patients. DESIGN: A total of 4634 specimens were obtained. Patient's nasal, scalp, and rectal swabs as well as tracheal secretion (TS) were cultured every second day beginning on the day of admission. Nasal swabs and hand cultures of the personnel as well as cultures from gowns were also taken. All isolates of S. aureus were phage typed and 116 of these isolates were also plasmid typed. P. aeruginosa isolates were sero- and pyocin typed. Resistance patterns were determined in all isolates. SETTING: The study was carried out in the surgical intensive care unit (SICU) of an teaching hospital. PATIENTS: During the study period each patient (a total of 153 patients) admitted to the SICU entered the study. RESULTS: P. aeruginosa and S. aureus colonisation rate on admission were 5% and 36.5% respectively. Only 10 patients (6.5%) were colonized with P. aeruginosa during hospitalization, and only 7 patients (4.5%) acquired S. aureus in the surgical intensive care unit (SICU). The most common primary colonisation site of P. aeruginosa was the rectum, whereas S. aureus was predominantly found in nasal cultures. Horizontal transmission of S. aureus occurred in only 2 patients. CONCLUSION: The study suggests that colonisation with P. aeruginosa and S. aureus occurs from endogenous rather than from exogenous sources and that the endogenous acquisition of both bacteria play a more important role in development of nosocomial infections than the exogenous route of transmission.

Cross Infection↗
PubMed1990

Mechanism of imipenem resistance acquired by three Pseudomonas aeruginosa strains during imipenem therapy.

Imipenem sensitive pretherapy isolates (MICs 1-2 mg/l) and the corresponding resistant posttherapy isolates (MICs 16 mg/l) of Pseudomonas aeruginosa from three patients undergoing imipenem treatment were analyzed to establish the resistance mechanism. The identity of pyocin types, serotypes, DNA restriction endonuclease profiles and plasmid profiles strongly suggested isogenicity of pre- and posttherapy isolates. The imipenem resistant posttherapy isolates showed cross-resistance only to another carbapenem, meropenem. There were neither qualitative nor quantitative differences between pre- and posttherapy isolates in beta-lactamase production. Affinity of the penicillin-binding proteins 1A, 1B, 2, 3, 4,4' and 5 for [14C]imipenem was the same in pre- and posttherapy isolates. One-dimensional and two-dimensional gel electrophoresis of outer membrane protein preparations showed diminished expression of an outer membrane protein of about 46.5 and 47.5 kilodaltons, respectively, in the posttherapy isolates. This protein had an apparent isoelectric point of about pH 5.2 in two-dimensional gel electrophoresis. Growth in proteose peptone no. 2 broth did not reduce expression of this outer membrane protein, which spoke against its identity with the outer membrane protein D1. The permeability of the outer membrane for imipenem was reduced in the posttherapy isolates, since addition of 0.5 or 0.25 of the MIC of the permeabilizing agent ethylene-diaminetetraacetate reduced the MICs of imipenem for all isolates from each patient to the same (susceptible) level. The diminished expression of one of the outer membrane proteins might be the reason for this reduced permeability.

Bacterial Outer Membrane Proteins↗