H Milch

Országos Epidemiológiai Központ, Budapeŝto, Budapest, Hungary

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Publications (32)24.5 Total impact

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    ABSTRACT: To investigate the molecular epidemiology of ciprofloxacin-resistant CTX-M-15-producing Klebsiella pneumoniae epidemic clones (ECs) isolated from six nosocomial outbreaks and sporadic cases during 2005 in Hungary. Two hundred and eighty-one extended-spectrum beta-lactamase (ESBL)-producing K. pneumoniae clinical isolates collected from 41 centres were submitted to the National ESBL Reference Laboratory for further investigations. Of the 281 strains, 75 isolates proved to be SHV producers, whereas 6 isolates were ciprofloxacin-susceptible CTX-M-type ESBL producers. One hundred and ninety-six ciprofloxacin-resistant CTX-M-type beta-lactamase-producing isolates collected from 35 centres were subjected to macrorestriction profile analysis. Furthermore, molecular typing was performed by PCR and sequencing of several antibiotic resistance genes, plasmid profile analysis, transfer of resistance determinants and multilocus sequence typing (MLST). PFGE revealed the existence of three genetic clusters defined as ECs, where 129 isolates belonged to the previously described Hungarian EC (HEC), 46 isolates to epidemic clone II (EC II) and 21 isolates to epidemic clone III (EC III), respectively. All isolates harboured plasmids ranging from 2.0 to 230 kb. PstI digestion of plasmid DNA from transconjugants/transformants revealed diverse restriction patterns from distinct ECs. Sequence analysis of beta-lactamase genes from 19 selected isolates detected bla(CTX-M-15) and bla(OXA-1) in strains from all three ECs and bla(TEM-1) in EC III isolates located on large plasmids. ISEcpI associated with CTX-M-15 was detected only on a 50 kb non-conjugative plasmid from EC III. MLST identified three allelic profiles: ST 15 (HEC), ST 11 (EC III) and the novel ST 147 (EC II), which correspond to the PFGE clusters, respectively. In 2005, 97% of all CTX-M-producing K. pneumoniae isolates detected across Hungary were highly ciprofloxacin-resistant CTX-M-15 producers and represented just three stable genetic clones.
    Journal of Antimicrobial Chemotherapy 08/2008; 62(5):978-85. DOI:10.1093/jac/dkn287 · 5.31 Impact Factor
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    ABSTRACT: One hundred and twenty-six extended-spectrum beta-lactamase-producing clinical isolates of Klebsiella spp. were collected in 1998, 2002 and 2003 from seven outbreaks in neonatal intensive care units (NICUs) of five Hungarian county and teaching hospitals. The isolates were multidrug resistant but were susceptible to ciprofloxacin. Pulsed-field gel electrophoresis revealed the existence of 12 distinct genetic clones, 10 of which proved epidemic in the studied NICUs. All isolates harboured plasmids ranging from 2.3 kb to 228 kb, representing 12 diverse plasmid profiles. Sequence analysis of SHV-specific polymerase chain reaction products from 13 representative isolates detected the bla(SHV-2a) gene in three and the bla(SHV-5) gene in seven epidemic clones, respectively. In the majority of isolates the bla(SHV) genes were on transferable plasmids of 94kb. EcoRI and PstI digestion of plasmid DNA from transconjugants revealed identical or closely related restriction patterns in nine bla(SHV-5)-harbouring R-plasmids and in two bla(SHV-2a)-harbouring R-plasmids carried by strains obtained from geographically distant NICUs. Endemic clones in individual wards or epidemic clones affecting multiple healthcare facilities were not found. However, similarities observed in the size and restriction pattern of the plasmids hints at the multiple transfer of epidemic R-plasmids responsible for a sequence of outbreaks in Hungary.
    International Journal of Antimicrobial Agents 07/2007; 29(6):665-71. DOI:10.1016/j.ijantimicag.2006.12.020 · 4.30 Impact Factor
  • Hedda Milch · Judit Pászti · I Gadó · Katalin Glatz · Melinda Jakab ·
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    ABSTRACT: An account is given using typing methods and detection of virulence genes of different serotypes of Escherichia coli isolated in Hungary. By hybridization using SLT-I and SLT-II probes and PCR method using stx1-2, eae and ehx primers we could differentiate O157 strains of different serotypes into eight (stx, eae, ehxA positive; stx, eae positive; stx, ehxA positive; stx positive; eae, ehxA positive; eae positive; ehxA positive; stx, eae, ehxA negative) types. The discriminatory power of phage typing proves to be much higher than that of the plasmid profile. RAPD typing with different primers could confirm or exclude the subtypes identity of the isolated E. coli O157 serotypes. Escherichia coli O157:HNM isolates could be sorted in six different phage types and six different RAPD types with ERIC-1, in five RAPD types with ERIC-2 and in seven types with M13 primers. Escherichia coli O157:H7 showed six different phage types and three RAPD types with ERIC-1 and ERIC-2 and five types with M13 primers. According to our results the standard PFGE protocol [32] gives the opportunity to differentiate epidemiologically independent but evolutionary related or unrelated isolates, but the practical value of PFGE method for epidemiological purposes must be confirmed by other or more restriction enzymes or using an other protocol. Summarizing our results we suggest the use of phage and RAPD typing and in doubtful cases the PFGE method.
    Acta Microbiologica et Immunologica Hungarica 02/2003; 50(4):349-67. DOI:10.1556/AMicr.50.2003.4.4 · 0.78 Impact Factor
  • Hedda Milch · Judit Pászti · T Erdösi · M Hetzmann ·
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    ABSTRACT: An account is given on the activity of the National Center for Phage Typing of Staphylococci in Hungary in the period between 1997 and 2000 related to methicillin resistant Staphylococcus aureus (MRSA) strains originating mainly from hospital infections and sporadic cases. The rate of multiresistant MRSA strains has decreased gradually from 98.1% in 1997 to 74.6% in 2000, accordingly the typability by phages showed a considerable improvement by the international basic phages. Resistance pattern of MRSA strains became narrower in the period of the examinations. With the exception of erythromycin the rate of resistance decreased probably as a consequence of the increased use of erythromycin. The typing method was completed with the phenotypic and genotypic characterization of macrolide resistance. Among 73 MRSA strains type A was the most frequent macrolide resistance group, while type B, C1 and C2 occurred rarely. Type A was frequent also among the few MSSA and CNS strains. Out of the 168 examined S. aureus strains ermA genes occurred in 81.5%; in MSSA and CNS strains ermC1 genes were frequent, both genes are responsible for the target modification. The msrA gene, encoding the increased efflux, occurred only in CNS strains. Comparing the results obtained by phenotyping (phage typing) and genotyping (AP-PCR) methods it is of note that MRSA strains which proved non-typable by phage typing gave suitable results by the AP-PCR.
    Acta Microbiologica et Immunologica Hungarica 02/2001; 48(3-4):457-77. DOI:10.1556/AMicr.48.2001.3-4.14 · 0.78 Impact Factor
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    ABSTRACT: Comparison of phage types (PTs) determined by Felix and Callow's and Anderson's methods was performed testing 99 human strains of S. enterica serotype Typhimurium (S. typhimurium) isolated in Hungary. PT2 and PT2c--according to Felix-Callow--corresponded with Anderson's DT104 in case of 39 strains out of 40. Among 59 isolates belonging to other Felix-Callow's PTs only one strain was found which was DT 104. Similar unambiguous equalities could not be established between any other PTs comparing the two methods. The PTs of 17,877 human strains isolated between 1988 and 1999 were determined using Felix-Callow's method. On the basis of the above equality the emergence of DT104 could be followed retrospectively by means of the rate of PT2 and PT2c. The increase of DT104 began already in 1989, emerging first PT2c then PT2. It predominated since 1991 and it reached its maximum (78.3%) in 1999. The incidence of multiresistance among one of the groups of DT104 strains (Felix-Callow's PT2) was significantly higher in 1998 than the average of non-DT104 strains. The predominant R-type was ACST.
    Acta Microbiologica et Immunologica Hungarica 02/2001; 48(1):95-105. DOI:10.1556/AMicr.48.2001.1.9 · 0.78 Impact Factor
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    ABSTRACT: Between 1990-1994, a total of 16,505 S. enteritidis strains of human, animal and food origin were phage-typed, using the Hungarian scheme and the changes of incidence of the dominant phage types were monitored. The incidence of PT1 (corresponding to Ward's PT1 was very high between 1990 and 1992 (67.9-71.0% of the total S. enteritidis isolates), later, it decreased. The prevalence of PT6 (corresponding to Ward's PT4) was rare until 1992, then it gradually increased. The phage type and plasmid content of 78 Salmonella enteritidis strains were determined. Small plasmids were present in 59% of the isolates, together with a serotype-specific (38 MDa) plasmid. A correlation was found between the presence of the small plasmid and phage restriction to two phages used for subdividing the Hungarian phage types 1 (PT1) and 6 (PT6) of S. enteritidis (corresponding to PT1 and PT4 in Ward's typing scheme, respectively).
    Zentralblatt für Bakteriologie: international journal of medical microbiology 06/1998; 287(4):509-19. DOI:10.1016/S0934-8840(98)80192-8
  • H Milch ·
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    ABSTRACT: We give a short review about the two main groups of bacterial typing methods for epidemiological purposes: the phenotypic and genotypic methods. The advantage of the phenotypic methods is their feasibility for the less equipped laboratories, their disadvantages are the variability of the phenotypic properties, and their high labor requirement. The advantages of the genotypic typing methods are the higher discriminatory power and applicability of the same method for different species of bacteria. The disadvantage of these methods is that they are expensive and labour consuming. Beside the short description, we show the results of different authors obtained by the use of the molecular methods in the epidemiological practice and we call the attention to the insufficiency concerning the stability.
    Acta Microbiologica et Immunologica Hungarica 02/1998; 45(3-4):401-8. · 0.78 Impact Factor
  • I Gadó · Zs. Ruzsics · I Tóth · M Király · H Milch ·
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    ABSTRACT: Diagnostic value of multiplex polymerase chain reaction (PCR) was examined by using three primer pairs, specific for the common conserved region of stx1 and stx2, eae and an enterohaemolysin A gene (ehxA). The sensitivity in respect of each amplicon decreased with three exponents comparing to the individual PCR reactions. These PCR reactions were partially inhibited by the presence of certain additional primers. This inhibitory effect was template-concentration dependent, and was partially balanced by usage of increased amount of dNTP. Taq DNA polymerase in a range of 0.3-1.25 U/reaction did not influence the inhibition. The same inhibition was detected if the annealing temperature was changed from 48 degrees C to 57 degrees C. Pairs of EHEC primers inhibited a Salmonella enteritidis virulence-plasmid specific gene amplification, as well. Theoretical inhibiting effects were predicted by Primer Premier software but our observations can be sufficiently explained neither by the competitions between the specific and aspecific amplifications nor by the inhibition caused by dimerization of primers.
    Acta Microbiologica et Immunologica Hungarica 02/1998; 45(2):239-52. · 0.78 Impact Factor
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    ABSTRACT: OBJECTIVE: To determine the genetic relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from six provincial hospitals in Hungary between 1993 and 1994. METHODS: Molecular fingerprinting methods were used: hybridization with a mecA-specific DNA probe after ClaI restriction; hybridization with a probe for Tn554; and pulsed-field gel electrophoresis after Smal digestion of chromosomal DNA. RESULTS: All strains were resistant to penicillin, oxacillin, erythromycin, gentamicin, tetracycline, imipenem, and cephalosporins, and variably resistant to ofloxacin, clindamycin and tobramycin; all isolates were susceptible to vancomycin. Forty-eight of the 51 isolates carried the mecA gene as determined by Southern hybridization, using a mecA-specific DNA probe, indicating that the methodology used for initial identification may have been in error in three of the cases. Forty-seven of the 48 mecA-positive isolates showed very similar genetic backgrounds as defined by pulsed-field gel electrophoresis (PFGE) patterns after Smal digestion of chromosomal DNAs: a unique PFGE pattern was seen in 32 isolates and minor variants of it in 15 additional isolates. All the 47 isolates carried the same mecA polymorph (Clal type III), as determined by DNA hybridization after Clal digestion of chromosomal DNA. Only one of the MRSA isolates had a completely different PFGE pattern and a novel mecA polymorph. CONCLUSIONS: The findings demonstrate the existence of a unique, epidemic MRSA clone, in both invasive and colonizing strains, which is widely dispersed in Hungarian hospitals hundreds of kilometers apart.
    Clinical Microbiology and Infection 07/1997; 3(3):289-296. DOI:10.1111/j.1469-0691.1997.tb00616.x · 5.77 Impact Factor
  • H Milch · I Gadó · I Drin · E Czirók · M Herpay ·
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    ABSTRACT: The incidence of E. coli causing hemorrhagic colitis (HC) or non-bloody enteritis in Hungary was studied using SLT-I and SLT-II gene-probes as well as Vero-cell toxicity and Verotox-F tests. Out of 41 E. coli O157 strains isolated in Hungary between 1987 and 1996 15 strains (O157:HNM 4, O157:H77 8, O157:HNT 3) derived from hemorrhagic colitis (HC). Hybridization was observed with SLT-I and/or SLT-II in 19 strains. Verocytotoxin production of E. coli of 23 other serotypes was proven by hybridization of DNA probes. SLT production were demonstrated in 24 strains. Complex typing (sero-, phage-, colicin-typing and plasmid profile analysis) was carried out in E. coli serogroup O157 strains isolated from different geographical areas. Using the Hungarian phages the E. coli O157:HNM, O157-H7 strains could be distributed into 6 phage groups each and these phage groups could be further divided according to colicin production and plasmid profile. The Hungarian phage typing method for E. coli strains used since 1978 was compared to the method elaborated in Canada in 1990. Out of the most frequent Canadian phage types (1, 4, 8, 31, 14) phage types 8, 31 and 14 were observed in Hungary.
    Acta Microbiologica et Immunologica Hungarica 02/1997; 44(3):257-69. · 0.78 Impact Factor
  • H Milch · E Czirók · M Herpay · I Gadó · I Barcs ·
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    ABSTRACT: The degree of colonization was determined by complex typing (sero-, phage, colicin-, pyocin typing, plasmid profile analysis) of 212 Escherichia coli, 232 Klebsiella, 117 Pseudomonas aeruginosa and 52 Staphylococcus aureus strains isolated from nose, throat, ear and other sources of 563 new-born infants in gynaecological and maternity wards of two neonatal intensive care units (NICU I and II) during a one year period. The presence of Klebsiella strains was more frequent in NICU I and E. coli and P. aeruginosa in NICU II, S. aureus occurred in a low level in both units. In NICU I 34 kinds, in NICU II 43 kinds of E. coli serotype were found. In NICU I the accumulation of serotypes O6:H-, O6:H1, O19:H-, in NICU II O4:H-, O6:H1 was observed. The Klebsiella strains belonged in NICU I into 21, in NICU II into 12 phage types. Klebsiella was more frequent in NICU I than in NICU II, though the strains belonged to the same phage type in NICU II in 50.7%, but in NICU I 4 frequent and 19 rare phage types occurred. Sero- and pyocin typing was effective for typing of P. aeruginosa. The most frequent sero- and pyocin types were in NICU I:O11a,11b; in NICU II: O2a,2d,2f; 12v. The rate of antibiotic resistance in E. coli, Klebsiella, P. aeruginosa and S. aureus was nearly the same in both units, multiple resistance was more frequent in NICU I (except P. aeruginosa, it was multiple resistant in 100% in both units). In NICU I 267, in NICU II 174 infants were treated with antibiotics. The administration of penicillin derivatives was nearly similar in the two care units and the resistance among E. coli and Klebsiella strains was nearly the same too. Though, cephalosporins were used more frequently in NICU II, resistance to cephalosporins among E. coli and Klebsiella was a bit higher in NICU I. Aminoglycosides were more often used in NICU I, resistance to aminoglycosides among E. coli and Klebsiella was higher in this unit. The rate of isolation of the examined bacteria was significantly lower in the group treated with antibiotics, than in the untreated group.
    Acta Microbiologica et Immunologica Hungarica 02/1994; 41(2):127-51. · 0.78 Impact Factor
  • I Tóth · V Karcagi · B Nagy · I Gadó · H Milch ·
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    ABSTRACT: A total of 93 wild type Escherichia coli of human origin (mostly representing intestinal isolates from Hungary) were examined for the presence of Shiga-like-toxin (SLT) genes using SLT-I, SLT-II and enterohemorrhagic E. coli (EHEC) specific DNA probes. The structural genes of the above specificity were labelled by random priming using 32-P-dCTP. E. coli strains investigated represented 16 serogroups: O1, O2, O4, O5, O6, O18, O25, O26, O45, O55, O111, O125, O126, O128, O157, O165, members of which were likely to produce verotoxin (VT) and strains of serotypes O11:NM, ONT:NM isolated from six haemorrhagic uraemic syndrome (HUS) patients. Out of these strains 51 were examined for in vitro VT production capacity. Only one strain (an O26:H11 from Germany) produced VT. This was also the only strain which proved to be positive with one of the SLT probes (SLT-II), and with the EHEC probe. From this strain a phage was isolated which was proven to be nonconvertible. These data support epidemiological and clinical observations about the very low occurrence or absence of EHEC in Hungary, in contrast to many European countries.
    Acta Microbiologica et Immunologica Hungarica 02/1994; 41(3):259-64. · 0.78 Impact Factor
  • V G László · E S Csórián · H Milch ·
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    ABSTRACT: In the last 10 years several phage typing methods were developed for Salmonella enteritidis, leading to confusion in the predominant phage types (PT) reported from different countries. We made comparative examinations on 1487 S. enteritidis strains isolated in Hungary in 1990-1991, using two phage-sets: a modified version of the method elaborated by László et al. (here in after Hungarian method) and the system of Ward et al. (here in after Colindale method). Typability of the strains was nearly the same: 98.0% and 98.3%, the isolates belonging to 18 and 19 phage types, respectively. The Hungarian method revealed 6 (1, 1c, 1b, 1d, 7, 18), the Colindale method 5 (1, 6, 8, 21, 26) frequent phage types. In Hungary PT 1 has been predominant since 1981 and using the Colindale method 64% belonged to this type; using the modified Hungarian method this type could be divided into PT 1, PT 1c, PT 1b and PT 1d. Other frequent phage types (PT 18, PT 7) were nearly identical with Colindale types PT 26 and PT 21.
    Acta microbiologica Hungarica 02/1993; 40(3):255-63.
  • E Czirók · M Herpay · H Milch ·
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    ABSTRACT: A multivariate analysis of 3334 Escherichia coli strains originating from different clinical materials revealed that 50.2% of isolates belonged to the most common 12 (O1, O2, O4, O6, O7, O8, O15, O18, O45, O75, O78, O83) out of 133 serogroups. Haemolysin (Hly) production, mannose resistant haemagglutinating activity for human erythrocytes (MRHA) and colicinogenicity (Col) were recorded in 30, 30 and 36%, respectively. Antigens K1 and K5 were present in 11% and 6.6%, respectively. Association were found among certain serotypes and virulence markers (O1, H-, H7, K1, MRHA, Col; O2, H-, Kl, Col; O4, H-, H5, MRHA, Hly; O6, H-, H1, MRHA, Hly; O6, K5, MRHA, Col; O7, H-, H4, K1, MRHA, Col; O18ac, H7, K1, Col; O18ac, H-, K5, MRHA, Hly; O78, H-, Col (V-type); O83, H-, K1, Col). There were associations among clinical specimens, age of patients, nosocomial group of diseases, serogroups and virulence markers, too (cerebrospinal fluid-CSF-O7, O18ac, O45, O83-K1-newborn meningitis; O78-ColV-meningitis, sepsis, inflammations diseases of premature babies; CFS-O6, MRHA, Hly-adult-meningitis, sepsis, urinary tract infection-UTI-, pneumonia, other inflammatory diseases; blood-O2, O4, O6, O18ac, ONT, K5, MRHA, Hly-sepsis, UTI, hepatic diseases; urine-O1, O2, O4, O6, O18ac, O75, virulence markers fall to differ among upper and lower UTI; faeces-O1, O4, O6, O18ac, O78, virulence markers rare). Associations were also found among animal pathogenicity tests, specimens, serogroups and virulence factors: highly virulent group strains (i.e. LD50 below 10(6)) belonged to serogroups O2, O6, O18ac, possessed antigen K1 (less frequently the presence of MRHA, Hly, K5) and originated mainly from CSF. With mouse lung toxicity test correlations of serogroups (O4, O6, O18ac), antigen K5, MRHA, Hly and specimens (blood) were also shown. However, association was found between the lack of virulence factors and phage insensitivity and also between K5 positivity and sensitivity to phages 16, 17, there were no correlations between serogroups and phage patterns. On the basis of the above-described associations one can find correlations among virulence markers, serotype, and nosological group of diseases. Animal pathogenicity tests give additional data in understanding the pathomechanism of diseases. Correlations between phage patterns and serogroups reveal certain epidemiological relatedness and also virulence of strains.
    Acta microbiologica Hungarica 02/1993; 40(3):217-37.
  • E Czirók · H Milch · M Herpay ·
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    ABSTRACT: Virulence factors (serogroup, haemolysis, haemagglutination, antigens K1, K5, colicinogenicity) and their association with diseases of 3334 Escherichia coli strains isolated from different clinical specimens between 1979-1990 were analysed. Strains, that were isolated from cerebrospinal fluid of newborns under one month were characterized by certain serogroups (O7, O18, O45, O78, O83), possession of antigen K1 and production of colicin. On the basis of their LD50 they belonged to the pathogenic group (i.e. < 10 10(6)) significantly more frequently than those isolated from other materials. Strains originating from blood cultures belonged frequently to serogroup O4, O6, O18 and were haemolytic. Their pathogenicity was proved by mouse lung toxicity test. Properties of strains isolated from wound and throat swabs, urinary samples resembled to that of strains originating from blood cultures in many respects, expressing the fact that bacteria settle in different organs before sepsis is developing. Frequent occurrence of strains with antigen K1, haemolysin and haemagglutination positivity in vaginal swabs expose newborns to danger. Knowledge of virulence markers and prevention of infections are associated.
    Orvosi Hetilap 11/1992; 133(45):2897-900, 2905-7.
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    ABSTRACT: Oxoid VET-RPLA, ST-EIA and Pharmacia Phadebact ETEC-LT enterotoxin tests were compared to find a simple but reliable method for detecting enterotoxigenic Escherichia coli (ETEC) in Hungary. In the Oxoid tests, all six reference LT- or ST-producing strains, except one ST-producer, gave positive results. Of 11 reference porcine enterotoxigenic strains, all four LT-producers gave positive reactions for LT but three of 10 ST-producers gave negative reactions for ST. Thirteen of 50 strains from culture collections of H. Steinrück (Germany) were LT+ and nine of 33 were ST+. When 31 isolates were tested simultaneously with the Oxoid and the Pharmacia LT tests, 12 strains were LT+ by the Oxoid LT test but by the Phadebact LT test only seven of these strains were LT+ and, of the remainder, three gave uncertain results and two gave negative results. Of 69 porcine strains, seven were LT+ and three ST+. Of 901 human strains isolated in Hungary, 10 were LT+ and one of 24 tested was ST+. In two cases, ETEC strains were isolated from contacts of travellers returning from Mongolia and Bangladesh. Results of comparative studies with reference strains corresponded well to those of the classical toxin detection tests. The Oxoid test was rapid, sensitive, specific and easy to perform and is recommended for use in screening ETEC isolates.
    Journal of Medical Microbiology 07/1992; 36(6):398-402. DOI:10.1099/00222615-36-6-398 · 2.25 Impact Factor
  • M Herpay · E Czirók · E Szöllösy · J Fekete · I Gadó · H Milch ·
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    ABSTRACT: Hydrophobic property of 136 Escherichia coli strains was examined by salt aggregation test (SAT). Out of the tested strains 61 were SAT positive. The correlations among the surface properties characterized by SAT and other phenotypical properties, e.g. mannose resistant haemagglutinating activity (MRHA), mannose sensitive haemagglutinating activity (MSHA), presence of antigen K1 and adsorption to Al(OH)3 gel were examined. The results showed that (i) Possession of antigen K1 provides the bacterial cell a hydrophilic character and covers its relative surface hydrophobicity; (ii) Correlation exists between the relative hydrophobicity of the bacteria determined by SAT and their haemagglutinating activity. SAT values are also influenced by non haemagglutinating fimbriae and also by other non fimbrial structures; (iii) The hydrophilic surface characters are mainly expressed by the results of adsorption to Al(OH)3 gel and the hydrophobic characters rather by the SAT values.
    Acta microbiologica Hungarica 02/1991; 38(1):17-28.
  • H Milch · E Czirók · I Gadó · M Herpay · M Jakab · G Szalai · J Lantos · L Kiss · T Sztroj · K Csiszár ·
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    ABSTRACT: A significant difference was observed in the occurrence of the examined markers (Col+, ColV+, Hly+, Aer+, AbR) and in the plasmid carrier state between strains with and without K1 and K5 antigens. Plasmids of the same size were harboured by serotypes possessing K1 and K5 antigens, e.g. among O1: K1: H- strains plasmids of 60-79 Md, among O1: K1: H7, O18ac: K1: H7, O45: K1: H7 and O83: K1: H- strains plasmids of 80-95 Md were frequent. The average plasmid number was higher in K1 strains than in K5 strains. In serogroup O1 the frequency of the plasmid carrier state was associated with the O serogroup and not with the K antigen. The plasmid number in K5 of serogroups O6 and O18 was lower than in K5- strains. Plasmids of 80-95 Md were predominant among the strains derived from blood and cerebrospinal fluid, whereas these plasmids were rare among the K1 and K5 strains isolated from other sources. Plasmids of 60-79 Md were frequent among strains derived from different sources. The 30-40 Md plasmids were relatively frequent among strains isolated from urine. In contrast with literary data, O1: K1: H-, O1: K1: H7 and other frequent serotypes consisted of different clones. Different clones were found within a single serotype, too.
    Acta microbiologica Hungarica 02/1991; 38(1):61-73.
  • I Gadó · I Tóth · H Milch · E Czirók · M Herpay ·
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    ABSTRACT: Of 182 wild-type human, aerobactin producer Escherichia coli strains 86.3% were insensitive to cloacin. All randomly chosen 51 strains were relatively cloacin tolerant. Cloacin tolerant strains were not considerably more sensitive to hydrophobic drugs than the cloacin sensitive descendant strains. Pathogenicity of the cloacin sensitive strains was significantly lower (p less than 0.05) in intraperitoneal mice infection than that of the cloacin tolerant ones. Suggesting a new aspect of the uptake mechanism of colicins, cloacin tolerance was very frequently associated with an aspecific insensitivity to a broad spectrum of colicins.
    Acta microbiologica Hungarica 02/1991; 38(2):95-105.
  • E Czirók · H Milch · K Németh · I Gadó ·
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    ABSTRACT: The in vitro and in vivo effects of human lactoferrin (LF), apoLF, iron saturated LF and of different iron containing compounds (ferric chloride, ferric sodium citrate) were studied on Escherichia coli, Salmonella typhi-murium and Pseudomonas aeruginosa reference and wild-type strains with well-defined virulence markers (i.e. enterochelin, aerobactin production). LF exert in vitro antibacterial effect, and iron-free Vogel-Bonner medium proved to be suitable for its determination. The effect of intraperitoneally administered LF could not be evaluated because of its aspecificity, as any treatment (e.g. saline, Ringer solution) before bacterial challenge activated macrophages. In contrast to the in vitro results, intramuscular challenge failed to inhibit bacterial growth in vivo, as siderophores produced by bacteria were able to acquire lactoferrin-bound iron. LF treatment, like iron addition, enhanced the virulence of bacteria in mice, whereas apoLF - using iron present in the body fluids - turned to LF being unable to acquire siderophore-bound iron from bacteria. These findings do not support the literary view that LF would be useful as an antimicrobial drug.
    Acta microbiologica Hungarica 02/1990; 37(1):55-71.