Multi-drug resistance pattern and genome-wide SNP detection in levofloxacin-resistant uropathogenic Escherichia coli strains

OBJECTIVES

Antibiotic treatment is extremely stressful for bacteria and has profound effects on their viability. Such administration induces physiological changes in bacterial cells, with considerable impact on their genome structure that induces mutations throughout the entire genome. This study investigated drug resistance profiles and structural changes in the entire genome of uropathogenic Escherichia coli (UPEC) strains isolated from six adapted clones that had evolved under laboratory conditions.

METHODS

Eight UPEC strains, including two parental strains and six adapted clones, with different fluoroquinolone resistance levels originally isolated from two patients were used. The minimum inhibitory concentration (MIC) of 28 different antibiotics including levofloxacin was determined for each of the eight strains. In addition, the effects of mutations acquired with increased drug resistance in the levofloxacin-resistant strains on expression of genes implicated to be involved in drug resistance were examined.

RESULTS

Of the eight UPEC strains used to test the MIC of 28 different antibiotics, two highly fluoroquinolone-resistant strains showed increased MIC in association with many of the antibiotics. As drug resistance increased, some genes acquired mutations, including the transcriptional regulator acrR and DNA-binding transcriptional repressor marR. Two strain groups with genetically different backgrounds (GUC9 and GFCS1) commonly acquired mutations in acrR and marR. Notably, acquired mutations related to efflux pump upregulation also contributed to increases in MIC for various antibiotics other than fluoroquinolone.

CONCLUSIONS

The present results obtained using strains with artificially acquired drug resistance clarify the underlying mechanism of resistance to fluoroquinolones and other types of antibiotics.

Study of normal flora in the pharynx of healthy children

To improve our current understanding of normal flora in children, we investigated bacterial isolates from pharynx and nasopharynx of 173 and 233 healthy children, respectively. The bacterial isolation rates were compared among three age groups: infants (<1 year), toddlers (1-5 years), and school-age children (6-15 years). Gram-positive cocci (GPC) were the predominant bacteria in the pharynx (Streptococcus mitis/oralis, 87.3%; Streptococcus salivarius, 54.3%; Rothia mucilaginosa, 41.6%; Staphylococcus aureus, 39.3%). Among infants, Streptococcus salivarius and Neisseria subflava, which are related to the development of teeth, were significantly lower than in the other age groups (p<0.0001, S. salivarius; p<0.01, N. subflava). Gram-negative rods (GNR) predominated the nasopharynx (Moraxella catarrhalis, 32.1%; and Moraxella nonliquefaciens, 28.3%) except for Corynebacterium pseudodiphtheriticum (44.2%) of gram-positive rods. Among toddlers, Moraxella catarrhalis and Streptococcus pneumoniae, which are the most common pathogens in acute otitis media, were significantly higher than in the infant group (p<0.05 for both). Among bacterial species implicated in pediatric respiratory infection, Streptococcus pyogenes was isolated in 3.5% of pharyngeal samples. S. pneumoniae and Haemophilus influenzae were isolated in 22.3% and 17.2% of nasopharyngeal samples, respectively. In conclusion, normal flora of the respiratory tract differs not only by sampling site but also by age group.

Induction of plasmid-mediated AmpC β-lactamase DHA-1 by piperacillin/tazobactam and other β-lactams in Enterobacteriaceae

Chromosomal AmpC β-lactamase induction by several types of β-lactams has been reported, but not enough data are available on DHA-1 β-lactamase, a plasmid-mediated AmpC β-lactamase. Therefore, we evaluated the DHA-1 β-lactamase induction by various antibiotics including piperacillin/tazobactam (PIP/TZB) in this study. Six strains (Enterobacter cloacae 2 strains, Citrobacter freundii 1 strain, Serratia marcescens 2 strain, and Morganella morganii 1 strain) possessing chromosomal inducible AmpC β-lactamase were used as controls. Four strains (Escherichia coli 2 strains, Klebsiella pneumoniae 1 strain, and C. koseri 1 strain) possessing DHA-1 β-lactamase were used. The β-lactamase activities were determined by a spectrophotometer using nitrocefin. β-lactamase induction by PIP, PIP/TZB was not observed in any strains and β-lactamase induction by third- and fourth-generation cephems was not observed in most strains. The induction ratios of the chromosomal AmpC β-lactamase in the reference group by PIP/TZB were <1.51, and those of the DHA-1 β-lactamase were <1.36, except for K. pneumoniae Rkp2004 (2.22). The β-lactamase induction by first- and second-generation cephems, flomoxef, and carbapenem differed in each strain. Cefmetazole (CMZ) strongly induced β-lactamase. This study demonstrated that the induction of DHA-1 β-lactamase was similar to that of chromosomal AmpC using various Enterobacteriaceae, although the induction of β-lactamase in both groups by PIP/TZB was low. We also reported that the induction of PIP/TZB, a β-lactamase inhibitor combination antibiotic, against various AmpC-producing Enterobacteriaceae, including DHA-1 producers, was low.

Molecular epidemiology and clinical features of extended-spectrum beta-lactamase- or carbapenemase-producing Escherichia coli bacteremia in Japan

Objectives

To identify risk factors and clinical outcomes in patients with bacteremia due to extended-spectrum beta-lactamase (ESBL) or carbapenemase-producing Escherichia coli, as well as to determine the prevalence and genetic background of such isolates.

Methods

Case control study was performed with patients with E. coli bacteremia between January 2008 and May 2013 (n = 115) at a tertiary university hospital in Japan. Cases had ESBL-producing E. coli (ESBL-EC) whereas controls had non-ESBL-producing E. coli (non-ESBL-EC) isolates. A retrospective chart review was performed to identify risk factors and clinical outcomes. Isolates were characterized by antimicrobial susceptibility testing, polymerase chain reaction analysis for beta-lactamase genes, and multi-locus sequence typing.

Results

Of 115 unique cases of E. coli bacteremia, 30 (26.1%) were due to ESBL-EC and three (2.6%) were due to carbapenemase-producing E. coli. All three carbapenemase-producing E. coli isolates were IMP-6 and concurrently produced ESBL (ESBL/IMP-6-EC). ESBL-EC isolates showed multidrug resistance. Of the ESBL-EC isolates, CTX-M-27 was the most prevalent (33.3%), followed by CTX-M-14 (30%). Multi-locus sequence typing revealed that 19 (63.3%) isolates were ST131. The multivariate analysis identified nursing home-associated infections and antibiotic administration in the preceding 30 days as risk factors for ESBL-EC bacteremia. The 14-day mortality non-ESBL-EC, ESBL-EC, and ESBL/IMP-6-EC was 4.7% (4/85), 20% (6/30), and 66.7% (2/3), respectively.

Conclusions

CTX-M-27, CTX-M-14, and ST131 were the most prevalent ESBL-EC isolates from bacteremic patients in a Japanese hospital. Further studies with larger sample sizes are warranted to investigate the clinical significance of ESBL-EC and ESBL/IMP-6-EC.

[Usefulness of real-time PCR in detecting Chlamydia trachomatis and Neisseria gonorrhoeae in endocervical swabs and first-voided urine specimens]

We evaluated performance of Abbott RealTime CT/NG assay (real-time PCR, Abbott Japan) for detect Chlamydia trachomatis and Neisseria gonorrhoeae by real-time PCR in 88 female patients with cervicitis symptoms seen at gynecological clinics and 100 male patients with urethritis symptoms seen at urological or dermatology clinics in Kitakyushu, Japan. Endocervical swab and first-voided urine (FVU) specimens were then collected from women and FVU specimens from men. Detection rates of C. trachomatis and N. gonorrhoeae by real-time PCR in the 3 types of specimens were compared to those by ProbeTec ET assay (ProbeTec, BD Diagnostic System). The overall positive concordance between real-time PCR and ProbTec were 97.1% (66/68) for C. trachomatis and 100% (33/33) for N. gonorrhoeae, C. trachomatis detection yielded 3 discordant results in endocervical specimens and 1 discordant result in male FVU by real-time PCR and ProbTec. Three of 4 reexamined using Aptime Combo 2 Assay (Fuji Rebio Inc.) were positive for C. trachomatis. Endocervical swab and FVU specimen results for C. trachomatis were discordant in 3 cases in real-time PCR and 4 in ProbeTec. Subjects with 2 or more positive endocervical awab results in female or male FVU specimens were assumed to be "true positive" for C. trachomatis. The sensitivities of real-time PCR for detecting C. trachomatis was 94.4% in endocervical swabs, 77.8% in female FVU and 97.4% in the male FVU. The sensitivities for real-time PCR for detectig N. gonorrhoeae was 100% in all 3 specimen types. Abbott RealTime CT/NG assay was useful for detecting C. trachomatis using endocervical swabs or male FVU specimens and for detecting N. gonorrhoeae using endocervical swabs and all FVU specimens.

The mechanism of high-level carbapenem resistance in Klebsiella pneumoniae: underlying Ompk36-deficient strains represent a threat of emerging high-level carbapenem-resistant K. pneumoniae with IMP-1 β-lactamase production in Japan

The mechanisms of high-level carbapenem resistance in Klebsiella pneumoniae isolated in Japan were investigated. High-level carbapenem-resistant K. pneumoniae Mkp4437 and a less carbapenem-sensitive K. pneumoniae strain, Mkp4365, were recovered from the same patient. These two strains were found to be homologous by pulsed-field gel electrophoresis, and both strains contained blaIMP-1, blaDHA-1, blaCTXM-14, blaTEM-1, and blaSHV-1. Based on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the lack of Ompk36 was observed in Mkp4437. Direct sequencing of the ompK36 gene demonstrated that a new insertional sequence in the open reading frame of the ompK36 gene was found in Mkp4437. Three clinical isolates (minimum inhibitory concentration [MIC] 2-4 mg/L to imipenem) were identified upon screening the strains of K. pneumoniae isolated in the University hospital with MICs of ≥ 1 mg/L to imipenem. Interestingly, these three isolates all lacked OmpK36. Conjugation of the plasmid harboring IMP-1 to these three OmpK36-deficient strains led to the isolation of high-level carbapenem-resistant transconjugants. In conclusion, the mechanisms of high-level carbapenem resistance in K. pneumoniae entail not only the production of IMP-1 β-lactamase but also the lack of OmpK36. It is vital to monitor for the presence of less carbapenem-sensitive K. pneumoniae strains, which lack OmpK36, because blaIMP-1 transmission to these strains may result in isolates with a high-level carbapenem-resistant phenotype.

The efficacy of sequential therapy using pazufloxacin followed by oral fluoroquinolones for treatment of pyelonephritis

The efficacy of sequential therapy of pazufloxacin (PZFX), which is a parenteral fluoroquinolone, followed by oral fluoroquinolones [tosufloxacin tosilate (TFLX) or levofloxacin (LVFX)] for treatment of pyelonephritis, was evaluated. Patients with pyelonephritis who had fever (≥37.5 °C), pyuria (≥10 white blood cells/high-power field), and bacteriuria (≥10(4) colony-forming units/ml) were eligible for this study. PZFX (500 mg) was given intravenously twice a day for at least 3 days. If the patients were clinically improved, TFLX (150 mg) or LVFX (100 mg) was then administered orally three times a day for at least 5 days. Patients underwent clinical and microbiological evaluation at 5-9 days after final drug administration. Clinical and microbiological efficacy could be assessed in 21 of 25 cases enrolled. Both clinical and microbiological efficacy rates were 81.0 % (17/21 cases). In the effective cases, the mean administration time was 4.2 days for PZFX and 6.0 days for oral fluoroquinolones. The mean time to defervescence was 3.4 days for the effective cases. In the four treatment failure cases, three quinolone-resistant Escherichia coli and a quinolone-resistant Enterococcus faecalis were isolated. This sequential therapy seemed to be clinically effective in the treatment of pyelonephritis; however, the prevalence of quinolone-resistant E. coli should be taken into account.

[Usefulness of real-time PCR in detecting Chlamydia trachomatis and Neisseria gonorrhoeae in endocervical swabs and first-voided urine specimens]

We evaluated performance of Abbott RealTime CT/NG assay (real-time PCR, Abbott Japan) for detect Chlamydia trachomatis and Neisseria gonorrhoeae by real-time PCR in 88 female patients with cervicitis symptoms seen at gynecological clinics and 100 male patients with urethritis symptoms seen at urological or dermatology clinics in Kitakyushu, Japan. Endocervical swab and first-voided urine (FVU) specimens were then collected from women and FVU specimens from men. Detection rates of C. trachomatis and N. gonorrhoeae by real-time PCR in the 3 types of specimens were compared to those by ProbeTec ET assay (ProbeTec, BD Diagnostic System). The overall positive concordance between real-time PCR and ProbTec were 97.1% (66/68) for C. trachomatis and 100% (33/33) for N. gonorrhoeae, C. trachomatis detection yielded 3 discordant results in endocervical specimens and 1 discordant result in male FVU by real-time PCR and ProbTec. Three of 4 reexamined using Aptime Combo 2 Assay (Fuji Rebio Inc.) were positive for C. trachomatis. Endocervical swab and FVU specimen results for C. trachomatis were discordant in 3 cases in real-time PCR and 4 in ProbeTec. Subjects with 2 or more positive endocervical awab results in female or male FVU specimens were assumed to be "true positive" for C. trachomatis. The sensitivities of real-time PCR for detecting C. trachomatis was 94.4% in endocervical swabs, 77.8% in female FVU and 97.4% in the male FVU. The sensitivities for real-time PCR for detecting N. gonorrhoeae was 100% in all 3 specimentypes. Abbott RealTime CT/NG assay was useful for detecting C. trachomatis using endocervical swabs or male FVU specimens and for detecting N. gonorrhoeae using endocervical swabs and all FVU specimens.

The nationwide study of bacterial pathogens associated with urinary tract infections conducted by the Japanese Society of Chemotherapy

This study was conducted by the Japanese Society of Chemotherapy and is the first nationwide study on bacterial pathogens isolated from patients with urinary tract infections at 28 hospitals throughout Japan between January 2008 and June 2008. A total of 688 bacterial strains were isolated from adult patients with urinary tract infections. The strains investigated in this study are as follows: Enterococcus faecalis (n = 140), Escherichia coli (n = 255), Klebsiella pneumoniae (n = 93), Proteus mirabilis (n = 42), Serratia marcescens (n = 44), and Pseudomonas aeruginosa (n = 114). The minimum inhibitory concentrations of 39 antibacterial agents used for these strains were determined according to the Clinical and Laboratory Standards Institute (CLSI) manual. All Enterococcus faecalis strains were susceptible to ampicillin and vancomycin. Although a majority of the E. faecalis strains were susceptible to linezolid, 11 strains (7.8%) were found to be intermediately resistant. The proportions of fluoroquinolone-resistant Enterococcus faecalis, Escherichia coli, Proteus mirabilis, and S. marcescens strains were 35.7%, 29.3%, 18.3%, and 15.2%, respectively. The proportions of E. coli, P. mirabilis, K. pneumoniae, and S. marcescens strains producing extended-spectrum β-lactamase were 5.1%, 11.9%, 0%, and 0%, respectively. The proportions of Pseudomonas aeruginosa strains resistant to carbapenems, aminoglycosides, and fluoroquinolones were 9.2%, 4.4%, and 34.8%, respectively, and among them, 2 strains (1.8%) were found to be multidrug resistant. These data present important information for the proper treatment of urinary tract infections and will serve as a useful reference for periodic surveillance studies in the future.

Clinical effects of 2 days of treatment by fosfomycin calcium for acute uncomplicated cystitis in women

Fosfomycin calcium is a fosfomycin antimicrobial agent with a characteristic structure. After oral administration, the drug is absorbed and excreted via the kidneys in the unchanged form, without being metabolized in the body. It is, therefore, indicated for the treatment of urinary tract diseases, including cystitis and pyelonephritis. In the present study, the clinical usefulness of fosfomycin calcium (FOSMICIN® TABLETS 500) administered orally at the dosage of 1 g (two tablets) three times daily for 2 days was examined in female patients, who were at least 20 years of age, with acute uncomplicated cystitis of bacterial origin. Of the 48 patients enrolled between February 2008 and August 2008, 39 were evaluable for efficacy and safety. Overall evaluation of the cure revealed that microbiological eradication rate (microbiological outcome) and clinical efficacy rate (clinical outcome) at 5-9 days after drug administration (visit 2) were 94.9%. Determination of the microbiological and clinical outcomes for the evaluation of recurrence at 4-6 weeks after drug administration (visit 3) were 75.8 and 85.7%, respectively. Of the 48 patients, 40 (83.3%) returned to the clinic at visit 3. The causative bacterial species for cystitis was Escherichia coli in 31 (79.5%) of the 39 patients evaluable for efficacy and safety. Adverse drug reactions observed during the administration and follow-up periods included mild diarrhea and loose stools in 1 patient each, neither requiring any specific treatment. Evaluation of cure at visit 2 in patients in whom the causative bacterial species for the infection was E. coli revealed a microbiological outcome of 93.5%, and clinical outcome was 96.8%. Furthermore, evaluation for recurrence at visit 3 revealed a microbiological outcome of 74.1% and clinical outcome of 82.1%. When the patients were divided by age into an under 60 years of age group and an over 60 years of age group, the microbiological and clinical outcomes determined for evaluation of cure at visit 2 were 96.4 and 92.9%, respectively, and the corresponding rates determined for the evaluation of recurrence at visit 3 were 87.0 and 96.0%, respectively, in the under 60 years of age group. In the over 60 years of age group, the corresponding microbiological outcome and clinical outcome rates evaluated for cure were 90.9 and 100%, respectively, and those evaluated for recurrence were 50.0 and 60.0%, respectively. These results indicate the usefulness of fosfomycin calcium administered at 1 g three times daily for 2 days for acute uncomplicated cystitis.

Molecular mechanisms of fosfomycin resistance in clinical isolates of Escherichia coli

To clarify the molecular mechanisms of fosfomycin resistance in clinical isolates of Escherichia coli, the murA, glpT, uhpT, uhpA, ptsI and cyaA genes were sequenced from six fosfomycin-resistant isolates. Two strains were found to harbour a mutation in the murA gene that leads to an amino acid substitution (Asp369Asn or Leu370Ile) in the target protein. The remaining four strains carried specific mutations in the glpT gene; one strain possessed a mutation and the other three strains possessed truncated versions of the GlpT transporter owing either to the presence of insertion sequences or a deletion in the coding region of the gene. Two of the strains with truncated GlpT had also lost the entire uhpT gene, which encodes another fosfomycin transporter. Uptake of specific substrates for the transporters was either totally blocked or reduced in strains possessing truncated forms of GlpT or those lacking the uhpT gene. Escherichia coli strains expressing an amino-acid-substituted MurA were at least eight-fold more resistant to fosfomycin than the strain overproducing wild-type MurA. In conclusion, novel amino acid substitutions in MurA or the loss of function of transporters were identified as mechanisms of fosfomycin resistance in clinical isolates of E. coli.

[Drug susceptibility of bacteria isolated from pediatric respiratory infections at general practitioners' clinics to pediatric antibiotics]

Four major causative bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes) of pediatric respiratory infections, 295 clinical isolates in total, were isolated at general practitioners' clinics in Sendai city, and evaluated the drug susceptibility to seven antibiotics for pediatric. Penicillin-resistant S. pneumoniae and penicillin-intermediate S. pneumoniae (PRSP-PISP) were 55.8% of all S. pneumoniae isolates. The MIC90 of penicillin and cephalosporin antibiotics in S. pneumoniae were good, 0.5-1 microg/mL, however, macrolide-resistant strains remarkably increased. As for H. influenzae, 50.0% of all isolates were ampicillin-intermediate and -resistant (MIC: > or = 2 microg/mL), the MIC90s of cephalosporin antibiotics had large differences between 0.5 to 8 microg/mL, and generally less susceptibility was shown to other antibiotics. M. catarrhalis showed less susceptibility to amoxicillin which behaved unstably to penicillinase, on the other hand, the MIC90s of other antibiotics were relatively good, 0.25-1 microg/mL. S. pyogenes remarkably tend to be resistant to macrolide antibiotics, however, the MIC90s of penicillin and cephalosporin antibiotics were very good, 0.03-0.06 microg/mL. Pediatric respiratory infections are required a treatment which results in inhibition of drug-resistant bacteria. Based on the results of drug susceptibility testing, we should make a proper selection of antibiotics by reference to disposition such as drug concentration in serum and transfer into cells.

[Antimicrobial activity of tebipenem against various clinical isolates from various specimen, mainly urinary tract]

Tebipenem is the active metabolite of ME1211, tebipenem pivoxil, a novel oral carbapenem that possesses potent activity against almost pathogens except for Pseudomonas aeruginosa. In this study, we compared the susceptibility of tebipenem with current antibiotics against various organisms isolated from various specimen, mainly urinary tract. Tebipenem had a potent activity against Neisseria gonorrhoeae; its activity was comparable to it of cefixime that has most potent activity among oral antibiotics. Against Enterococcus faecalis, the activity of tebipenem was comparable to the activities of ampicillin and amoxicillin, and superior to it of faropenem. Against Citrobacter freundii, Escherichia coli , Klebsiella pneumoniae, and Enterobacter spp. including extended-spectrum beta-lactamase producers, tebipenem had a potent activity with or without ceftazidime-resistance.

Genetic profiles of fluoroquinolone-resistant Escherichia coli isolates obtained from patients with cystitis: phylogeny, virulence factors, PAIusp subtypes, and mutation patterns

The low virulence of quinolone- and fluoroquinolone-resistant Escherichia coli strains is known, although the reasons for this remain unclear. We surveyed the mutation patterns of quinolone resistance determining regions (QRDRs), phylogenetic distribution, prevalence of 18 urovirulence genes, and PAIusp subtypes in 89 fluoroquinolone-resistant E. coli (FQREC) isolates obtained from patients with cystitis and compared them with those of their fluoroquinolone-susceptible counterparts (FQSEC). Phylogenetic group B2 was significantly less prevalent in FQREC than in FQSEC (49% versus 78%; P=0.0138), but it still dominated, followed by phylogroup D (35%), in FQREC. When the prevalences of virulence factor (VF) genes were compared between FQREC and FQSEC, sfa/foc, cnf1, hly, kpsMT, ompT, ibeA, usp, and iroN showed significantly lower prevalences in FQREC than in FQSEC (1.1% versus 24% [P<0.0001], 0% versus 29% [P<0.0001], 7.9% versus 33% [P<0.0001], 74% versus 90% [P=0.01], 71% versus 87% [P=0.017], 5.6% versus 37% [P<0.0001], 54% versus 82% [P<0.0001], and 7.9% versus 32% [P=0.0001], respectively), whereas aer, iha, and ETTT showed significantly higher prevalences in FQREC (85% versus 36% [P<0.0001], 66% versus 29% [P<0.0001], and 53% versus 16% [P<0.0001], respectively). Furthermore, a similar difference in prevalences of uropathogenic VF genes was seen between FQREC and FQSEC in phylogroup B2. This indicated that the low virulence in FQREC was intimately correlated with a lesser distribution of VFs in phylogroup B2, which dominated in FQREC and FQSEC. It was interesting that the mutation pattern of Ser83Leu and Asp87Asn encoded in gyrA and Ser80Ile and Glu84Val encoded in parC was frequently found in FQREC isolates that belonged to phylogroup B2 and that most of these isolates showed PAIusp subtype 2a. PAIusp subtypes 1a, 1b, and 2b, which were frequently seen in FQSEC, were rarely found in FQREC. These results suggested that the acquisition of fluoroquinolone resistance, e.g., mutations in QRDRs, might be a specific event in limited strains, such as those that possess PAIusp subtype 2a in phylogroup B2.

Genetic analysis of faropenem-resistant Enterococcus faecalis in urinary isolates

We isolated faropenem-resistant Enterococcus faecalis in urine specimens and studied the mechanisms of resistance to faropenem in these isolates. Three mechanisms of penicillin resistance have been reported in E. faecalis; (1) beta-lactamase production, (2) overproduction of penicillin-binding protein (PBP) 4 or PBP5, and (3) decreasing affinities of penicillins for PBP4 by the occurrence of point mutations of the penicillin-binding domain. None of the E. faecalis isolates examined produced beta-lactamase or overproduced any PBPs, but the affinities of faropenem for PBP4 were decreased in faropenem-insensitive and -resistant strains. We found single amino acid substitutions at positions 475, 520 or 605 in PBP4 in the insensitive strains and two amino acid substitutions at positions 520 and 605 in PBP4 in the resistant strains by sequencing the entire pbp4 gene from each isolate. We conclude that development of resistance to faropenem in E. faecalis is due to decreasing affinities for PBP4 that are the result of the occurrence of one or two point mutations.

Single-dose treatment of male patients with gonococcal urethritis using 2g spectinomycin: microbiological and clinical evaluations

The microbiological and clinical efficacies of a single-dose treatment of 2g spectinomycin administered by intramuscular injection were studied in 365 male patients with gonococcal urethritis. A total of 210 patients (57.5%) could be evaluated, in 28 (13.3%) of whom Chlamydia trachomatis was detected in addition to Neisseria gonorrhoeae. A single dose of spectinomycin eradicated N. gonorrhoeae in 203 (96.7%) of the 210 patients. Among patients in whom N. gonorrhoeae was eradicated, pyuria and clinical symptoms, respectively, disappeared in 92.6% (162/175) and 98.9% (173/175) of patients without concomitant C. trachomatis and in 78.6% (22/28) and 71.4% (20/28) with C. trachomatis. Minimal inhibitory concentrations (MICs) were determined for four of seven N. gonorrhoeae strains isolated after spectinomycin treatment. MICs to spectinomycin for three of the four isolates were 16 microg/mL (defined as susceptible) and the MIC of the other isolate was 128 microg/mL, indicating resistance. The resistant isolate was a multidrug-resistant strain with resistance to ciprofloxacin, tetracycline, penicillin and cephalosporins, except for ceftriaxone. The results of this study indicate that a single-dose treatment using 2g spectinomycin is effective in treating patients with urethritis caused by N. gonorrhoeae, even in the era of multidrug-resistant N. gonorrhoeae.

Multiple doses of cefodizime are necessary for the treatment of Neisseria gonorrhoeae pharyngeal infection

A single dose of cefodizime (CDZM), ceftriaxone (CTRX), or spectinomycin (SPCM) is recommended for the treatment of gonococcal urethritis or uterine cervicitis in the era of multidrug-resistant Neisseria gonorrhoeae; namely, cefozopran-resistant N. gonorrhoeae (CZRNG). N. gonorrhoeae pharyngeal infection is not so rare in Japan; however, the proper treatment regimen for this infection is not clear. We previously found that a single dose of CDZM completely eradicated multidrug-resistant N. gonorrhoeae in patients with urethritis and uterine cervicitis, so we tried a single 1.0-g dose of CDZM for the treatment of N. gonorrhoeae pharyngeal infection, including infections with CZRNG. The eradication rate of N. gonorrhoeae from the pharynx was 63.0% with a single 1.0-g dose of CDZM, while the rate for CZRNG with the same dose of CDZM was 38.5%. N. gonorrhoeae was completely eradicated from the pharynx when patients received one or two additional doses of CDZM. Therefore, we concluded that two to three doses of CDZM were necessary for the treatment of N. gonorrhoeae pharyngeal infection including infection with CZRNG.

Urinary tract infection caused by fluoroquinolone- and cephem-resistant Enterobacteriaceae

In 2001, fluoroquinolone-resistant Escherichia coli isolates emerged in Japan in patients with uncomplicated urinary tract infection (UTI), and accounted for ca. 8% of isolates. This is a worldwide occurrence as reported by the ECO.SENS study. The number of fluoroquinolone- and cephem-resistant Enterobacteriaceae isolates from patients with complicated UTI is increasing. Most cephem-resistant isolates of E. coli, Klebsiella pneumoniae and Proteus mirabilis produce extended-spectrum beta-lactamases (ESBLs). The rates of ESBL-producing Enterobacteriaceae differ between countries but there are ESBL producers in urinary Enterobacteriaceae isolates in most countries. More seriously, most nosocomial ESBL producers are also resistant to non-beta-lactams, such as the fluoroquinolones, fosfomycin and co-trimoxazole. This causes serious problems in the chemotherapy of cystitis.

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004). III. Secular changes in susceptibility]

The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from patients diagnosed as urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The susceptibilities of these bacteria to various antimicrobial agents were measured. The bacteria were divided into 2 groups consisting of uncomplicated UTIs and complicated UTIs (with and without indwelling catheter) based on their isolation origins. The results were compared with those obtained between 1995 and 2003. The drug sensitivity of S. aureus in this year was similar to those in up to the previous year and S. aureus showed the best susceptibility to vancomycin (VCM) and arbekacin (ABK). The drug sensitivity of E. faecalis in this year also was similar to those in up to the previous year. The susceptibility of E. coli to cephems in this year was generally good and was similar to those in up to the previous year. MIC90 of cefozopran (CZOP) was the most stable and 0.125 microg/mL or less since 1995. The susceptibility of E. coli to cefpirome (CPR) and cefotiam (CTM) also was good but to cefaclor (CCL), cefixime (CFIX), and cefpodoxime (CPDX) was largely decreased in complicated UTI groups. The sensitivity of E. coli to carbapenems also was good but to carumonam (CRMN) tended to decrease. The susceptibility of E. coli to quinolones, however, has largely changed and has decreased since 2003 in uncomplicated UTIs and 2000 in complicated UTIs. That was suggested the development of the resistance to the drug. The susceptibility of Klebsiella spp. to cefazolin (CEZ), CTM, CCL, CPDX, and cefditoren (CDTR) decreased in the previous year and recovered to the year before the previous year in this year. The susceptibility of Klebsiella spp. to other cephems was stable since 1995, especially against CZOP, the highest sensitivity (MIC90: < or = 0.125 microg/mL) was maintained. The susceptibility of Klebsiella spp. to carbapenems and CRMN also was good. The susceptibility of Klebsiella spp. to aminoglycosides was lower than to CZOP but was stable since 1995. The susceptibility of P. aeruginosa was generally low and has largely changed against the majority of the agents since 1995. The susceptibility of P. aeruginosa isolated from uncomplicated UTIs has largely changed against ceftazidime (CAZ), cefsulodin (CFS), CZOP, imipenem (IPM), meropenem (MEPM), aztreonam (AZT), CRMN, gentamicin (GM), and tobramycin (TOB). The susceptibility of P. aeruginosa isolated from complicated UTIs has largely changed against CSF, CZOP, MEPM, GM, and ciprofloxacin (CPFX). The susceptibility of P. aeruginosa isolated from complicated UTIs has been stable against amikacin (AMK). For annual changes in MIC50, TOB and IPM had a relatively stable and high activity (MIC50: 0.5-2 microg/mL).

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004) II. Background of patients]

Six hundred six bacterial strains isolated from 490 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The frequency of bacteria isolation stratified with patient clinical background was compared. The clinical background investigated included sex, age, type of infections, timing of antibiotics administration, and presence or absence of surgery affecting a decrease in defense against infection. The bacterial strains were stratified with the age and sex of the patients and the types of infections. In males, the number of patients aged less than 60 years was few and the complicated UTIs without indwelling catheter was observed most frequently. In females, the number of patients aged less than 60 years was comparatively more than in males. In all of ages except 0-19 and > or = 80 years, the ratio of the uncomplicated UTIs was high, accounting for 44.1-90.0% of all types of infections. In the present time, the bacteria most frequently isolated were Escherichia coli. Pseudomonas aeruginosa and Enterococcus faecalis also were relatively frequently isolated. E. coli most frequently isolated with the uncomplicated UTIs and P. aeruginosa and E. faecalis most frequently isolated with the complicated UTIs. With respect to the relation of these results to the age of the patients, in the uncomplicated UTIs, the isolation frequency of E. coli was the highest in all age groups except 0-19 years, accounting for 50% or higher. In the complicated UTIs without indwelling catheter, the isolation frequency of E. coli tended to be high in all age groups. In the complicated UTIs with indwelling catheter, P. aeruginosa were more frequently isolated. In comparison of causative bacteria in UTIs between before and after the administration of antibiotics, P. aeruginosa increased after the administration in any types of UTIs. In comparison of causative bacteria in UTIs with or without surgery, E. coli was more frequently isolated in the patients without surgery, while P. aeruginosa and E. faecalis were more frequently isolated in the patients with surgery in any UTIs.

[Antimicrobial susceptibility and mechanism of resistance to antibiotics for Escherichia coli O157 and verotoxin-producing E. coli isolated in northern Kyushu and Yamaguchi area]

The purpose of this study was to investigate the biochemical characteristics and antimicrobial susceptibility of Escherichia (E.) coli O157 and verotoxin-producing E. coli isolates from the Northern Kyushu Island and Yamaguchi area of Japan. A total of 54 isolates- 50 E. coli O157, 3 verotoxin-producing E. coli O26 and 1 verotoxin-producing E. coli O111 - were used in this study. Regarding H antigen, H7 type in E. coli O157 accounted for 98% (49/50), and residual 1 strain of E. coli O157 was untypable H type. Two of 3 E. coli O26 isolates were H11 type, residual 1 strain of E. coli O26 was untypable H type, and E. coli O111 isolate was non-motile strain. All 54 isolates were susceptible to cephems, fosfomycin, kanamycin, amikacin and co-trimoxazole. Tetracycline-resistant isolates existed in 13 of all 54 isolates, 5 of those 13 isolates had tetA, and the other 7 isolates had tetB. Eight amoxicillin-resistant isolates had TEM-1 beta-lactamase. Four of the 5 isolates that had tetA also had TEM-1 beta-lactamase. Nalidixic acid and 6 fluoroquinolone used had no insensitive or resistant isolates. Kanamycin-resistant isolates, fosfomycin- and nalidixic acid-insensitive isolates have been reported, so we must notice the antibiogram of such strains. It is important that the surveillance of antimicrobial susceptibility of enterohemorragic E. coli should be continued after this.

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004). I. Susceptibility distribution]

The bacterial strains isolated from 490 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The susceptibilities of them to many kinds of antimicrobial agents were measured. Of them, 577 strains were estimated as causative bacteria and used for the measurement. The strains consisted of 156 gram-positive bacterial strains (27.0%) and 421 gram-negative bacterial strains (73.0%). Against Staphylococcus aureus, arbekacin (ABK), vancomycin (VCM) showed the strongest activity and prevented the growth of all strains with 2 microg/mL. Against Enterococcus faecalis, ampicillin (ABPC) and VCM showed a strong antibacterial activity. The antibacterial activity of cephems to Escherichia coli was generally good, and especially cefozopran (CZOP) and cefpirome (CPR) showed the strongest activity (MIC90: < or = 125 microg/mL). Quinolone resistant E. coli [MIC of ciprofloxacin (CPFX): > or = 4 microg/mL] was detected at frequency of 18.8%, which was higher than that in the last year. Against Klebsiella pneumoniae, CZOP, meropenem (MEPM), and carumonam (CRMN) showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. The antibacterial activity of the other cephems was relatively good, and decrease in their activity observed in the last year study was not recognized. Against Serratia marcescens, imipenem (IPM) and gentamicin (GM) had the strongest antibacterial activity. Against Proteus mirabilis, CRMN showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. MEPM prevented the growth of all strains with 0.25 microg/mL. Next, cefmenoxime (CMX), ceftazidime (CAZ), CZOP, cefixime (CFIX), cefpodoxime (CPDX), and cefditoren (CDTR) showed a strong activity. The antibacterial activity of the drugs to Pseudomonas aeruginosa was generally low, and MIC90 of all the drugs was ranged from 32 to > 128 microg/mL except IPM and MEPM having 16 microg/mL. The antibacterial activities of CZOP and CAZ were considered to be relatively good on MIC50 comparison (MIC50: 2 microg/mL).

Emergence and prevalence of β-lactamase-producing Klebsiella pneumoniae resistant to cephems in Japan☆

Forty-six cephem-resistant Klebsiella pneumoniae strains with minimum inhibitory concentrations>8 microg/mL for cefpodoxime and cefmetazole were selected from clinical isolates obtained between 2000 and 2002 from eight hospitals on Northern Kyushu Island, Japan. We investigated the mechanisms of resistance to cephems in these 46 K. pneumoniae isolates. The results of isoelectric focusing of beta-lactamases produced by these isolates, polymerase chain reaction for detection of various Class A, Class B and Class C beta-lactamases, and determination of the sequence of the beta-lactamase structural gene showed that most of these isolates had various types of broad-spectrum beta-lactamases. Of the 46 isolates, 2 were CMY-2 beta-lactamase producers and 41 were DHA-1 beta-lactamase producers. Forty of the 41 DHA-1 beta-lactamase producers simultaneously produced SHV-12 extended-spectrum beta-lactamase (ESBL), and the remaining isolate simultaneously produced SHV-27. Furthermore, one DHA-1 and SHV-12 beta-lactamase producer also produced IMP-1 beta-lactamase. The only broad-spectrum beta-lactamase with another isolate was IMP-1. Chromosomal DNA restriction fragment analysis using XbaI suggested that nosocomial infection due to DHA-1 and SHV-12 beta-lactamase producers had occurred at two centres. This is the first report of nosocomial infection due to DHA-1 beta-lactamase-producing K. pneumoniae including other plasmid-encoded AmpC beta-lactamases in Japan. The mechanisms of resistance of 44 of the 46 isolates to cephalosporins and cephamycins were ESBL production and/or plasmid-encoded AmpC beta-lactamase and/or IMP-1 beta-lactamase production. For two isolates, the mechanism of resistance to could not be identified. These results show that it is necessary to minimise the prevalence of these resistant strains as it will be a very serious problem if organisms producing these broad-spectrum beta-lactamases increase in clinical situations. It is important to detect these strains sooner and to perform rigorous infection control earlier.

[Epidemiological survey of sexually transmitted male urethritis in Kyoto Prefecture]

The data of sexually transmitted urethritis in males have been collected at 24 institutes in Kyoto Prefecture since October, 2002. The data collected from January to December in 2004 are summarized herein. A total of 1,275 patients were diagnosed with urethritis during this period. Microbiological examinations isolated Neisseria gonorrhoeae alone in 368 (29%), Chlamydia tracomatis alone in 336 (26%), both in 85 (7%), and others in 453 (36%). Male patients under 20 years old tended to have Chlamydial urethritis, alone or combined with gonococcal infection, and had a predominant infectious source, a non-commercial-sexual-worker female partner, suggesting a profound problem in sexual life of adolescents. The urologist preferred to use quinolones as the first therapeutic modality against male urethritis. However, drug resistance of N. gonorrhoeae, especially against quinolones, has rapidly progressed, which was also observed by a sensitivity examination test. Antibiotics should be used adequately against male urethrits according to the recent guidelines.

Comparison of 3 Commercial Metallo-^|^beta;-lactamase Detection Kits

Using 41 metallo-beta-lactamase producing isolates and 8 metallo-beta-lactamase nonproducing and ceftazidime-resistant isolates from Kyushu Island, metallo-beta-lactamase was detected by 3 commercial metallo-beta-lactamase detection kits, which were Metallo-beta-lactamase SMA Eiken (SMA, disk diffusion, Eiken Chemical Co.), dry plate Eiken DPD1 (DPD, two-fold serial broth microdilution, Eiken Chemical Co). and Cica beta test I/ MBL (CIC, coloring reaction, Kanto Chemical Co.). Detection rate by SMA, DPD, and CIC was 97.5, 100, and 100%. Neither method used in this study produced false-positive or false-negative results. The rates of metallo-beta-lactamase nonproducer identification were 37.5%, 62.5%, and 100% for the SMA, DPD, and CIC kits, respectivily. These three methods have the following features, SMA is useful for routine work because SMA utilizes disk diffusion, which is widely used by medical technologists, and it is the least expensive of the three kits. CIC can detect metallo-beta-lactamase after only 15 minutes and can determine the presence of non-metallo-beta-lactamase producers at a high rate. DPD can simultaneously identify the MIC of some agents. Consequently these three metallo-beta-lactamase detection kits were very useful for detecting metallo-beta-lactamase producing isolates.

Single dose of cefodizime completely eradicated multidrug-resistant strain of Neisseria gonorrhoeae in urethritis and uterine cervicitis

Cefodizime (CDZM) has strong antimicrobial activity to Neisseria gonorrhoeae in vitro. However, multidrug-resistant N. gonorrhoea emerged and has been increasing in Japan. To know the effectiveness of CDZM on gonococcal urethritis and uterine cervicitis even in the era of multidrug-resistant N. gonorrhoeae, a clinical trial of single-dose therapy of CDZM for gonococcal urethritis and uterine cervicitis was conducted. N. gonorrhoeae was eradicated from 100% of patients with gonococcal urethritis and uterine cervicitis by a single dose of CDZM. In conclusion, CDZM is one of most suitable drugs for the treatment of gonococcal genital infection in the era of multidrug-resistant N. gonorrhoeae.

Efficacy of 1-day prophylaxis medication with fluoroquinolone for prostate biopsy

A prospective, randomized trial in which 236 patients received oral levofloxacin, either at 600 mg/day for 1 day (n = 124) or 300 mg/day for 3 days (n = 112). Urinalysis, plasma white blood cell count (WBC) (per mm3), and C reactive protein (CRP) (mg/dl) levels were checked before prostate biopsy (PBX), on the day after PBX, and on the seventh day after PBX. Two patients (1.61%) who received 600 mg for 1 day and 2 patients (1.79%) who received 300 mg for 3 days had febrile infectious complications. There was no statistically significant difference between levofloxacin at 600 mg for 1 day and levofloxacin at 300 mg for 3 days regarding the elevation of WBC and CRP. We can perform PBX safely with levofloxacin at 600 mg for 1 day as prophylaxis and recommend this method from the point of view of the decrease of antibiotic-resistant strains.

Mechanisms of resistance to imipenem and ampicillin in Enterococcus faecalis

We found ampicillin- and imipenem-resistant isolates of vanA-possessing Enterococcus faecalis with MICs of 8 to 16 microg/ml and 4 to 32 microg/ml, respectively. There have been few reports about penicillin- and imipenem-resistant E. faecalis. Two mechanisms of beta-lactam resistance in E. faecalis, the production of beta-lactamase and the overproduction of penicillin-binding proteins (PBPs), have been reported. The resistant isolates in the current study did not produce any beta-lactamases and analysis of the PBPs showed no overproduction. However, the affinities of PBP4 for beta-lactams in the resistant strains were lower than those of susceptible strains but the affinities of other PBPs for beta-lactams did not change. Accordingly, whole pbp4 fragments from these resistant isolates were sequenced. Two amino acid substitutions at positions 520 and 605 were observed in the highly resistant strains compared to the susceptible ones, Pro520Ser and Tyr605His, and a single Tyr605His amino acid substitution was found in the low-resistance strains. These two point mutations exist in the region between the active-site-defining motifs SDN and KTG of the penicillin-binding domain, the main target of beta-lactams. A strong correlation was seen between these substitutions and decreasing affinities of PBP4 to beta-lactams. In E. faecalis, resistance due to mutations in PBPs has not been reported, though it has in Enterococcus faecium. Our results suggest that development of high-level resistance to penicillins and imipenem depends on point mutations of PBP4 at positions 520 and 605.

[In vitro antibacterial activities of telithromycin against clinical isolates of Neisseria gonorrhoeae]

In vitro antibacterial activity of telithromycin (TEL) against the isolates of Neisseria gonorrhoeae (212 isolates) derived from urine or genital secretion in 2002 (April to December) was examined in comparison with those of macrolides (erythromycin [EM], clarithromycin [CAM]), penicillins (penicillin G [PCG]), cephems (cefodizime [CDZM], cefixime [CFIX]), quinolones (levofloxacin [LVFX]), tetracyclines (minocycline [MINO]), and aminoglycosides (spectinomycin [SPCM]). The MIC of TEL was ranged from < or = 0.039 to 0.25 microg/mL and the MIC50 and MIC90 of TEL were respectively 0.125 and 0.25 microg/mL, which were the lowest values compared with those of other oral antibacterial agents measured. When compared TEL with other agents in the order of the MIC50 and MIC90, TEL was more superior to EM and CAM (both eight times), MINO (four times and twice), and LVFX (16 and 64 times). The MIC90 of TEL was superior in twice though the MIC50 was the same in comparison with CFIX. The CDZM resistant strain did not exist and SPCM also inhibit growth with 32 microg/mL or less that was the breakpoint MIC excluding one stock though the PCG sensitive strain was only 1.4% in the injection drug. However, clinical breakpoint MIC is not established, but the efficacy of TEL is prospective because of its high antibacterial activity to inhibit growth of all stocks for gonococcus with 0.25 microg/mL. It is expected that TEL can become an oral antibiotic recommended for treatment of gonococcus if dosage and administration are considered.

[A bacteriological study of multiple-drug-resistant Pseudomonas aeruginosa isolates derived from 2 patients]

We investigated the isolation circumstances of multiple-drug-resistant Pseudomonas aeruginosa (MDRP) in the UOEH hospital and the bacterial analysis of isolated MDRP. From January to October 2003, MDRP was isolated from 2 patients. During this period, the isolation frequency of MDRP was 0.57% (2/350). Case 1 had 2 MDRP isolates from catheter urine, and case 2 had 5 MDRP isolates from pus. Regarding serotype, 2 isolates from case 1 were B type and the other 16 isolates from case 2 were E type. Pyomelanin was produced by 9 isolates of 16 E type isolates. The same PFGE patterns were observed in 2 isolates from case 1; that is, 9 pyomelanin producers from case 2 and the other 7 isolates from case 2, respectively. Metallo-beta-lactamase was produced by 2 isolates from case 1. bla(IMP) was detected from the 2 isolates by PCR, and the clones from case 1 were quite different from the clones from case 2. Regarding the pyomelanin producing isolates from case 2, although the clones were the same genetically, the MICs of imipenem and meropenem increased from 8 to > 32 microg/ml with the progress of time. In the UOEH hospital, 6 patients with MDRP isolates have been isolated so far, but these 6 patients are not correlated with each other. It is important that we detect and report MDRP as early as possible to prevent nosocomial infection.

No regional spread of vancomycin-resistant enterococci with vanA or vanB in Kitakyushu, Japan

Outbreaks of vancomycin-resistant enterococci (VRE) infection occur sporadically in Japan, and their frequency has been gradually increasing. We experienced a nosocomial outbreak of VRE in two hospitals in the city of Kitakyushu, and the spread of VRE strains was suspected in this area. To examine the prevalence rate of infection and colonization of VRE in Kitakyushu, we screened a total of 24 297 clinical samples from patients in hospitals and clinics in Kitakyushu from October through December 2002 for VRE. The isolates screened as positive for VRE accounted for 2.3% (566/24 297) of the tested clinical samples. Polymerase chain reaction (PCR) analyses for vanA, vanB, vanC1, and vanC2/3 were performed to confirm the screening test results. Neither vanA nor vanB genes were detected in any isolates. The 265 vanC1-positive isolates were Enterococcus gallinarum, and the 150 vanC2/3-positive isolates were E. casseliflavus. Other Enterococcus species were negative in this PCR-detection test. In this study, the PCR procedure was considered reliable and successful because although neither vanA nor vanB was detected, vanC1 and vanC2/3 were completely detectable. Therefore, we concluded that the regional spread of VRE with vanA and vanB had not occurred in Kitakyushu in 2002. In the near future, the prevalence of VRE with vanA or vanB is likely to increase in Japan, as it has in other countries. We should continue to find and prevent nosocomial outbreaks of infection and colonization by VRE.

[Questionnaire survey on the theory of antimicrobial prophylaxis in urologic surgery]

In order to establish an acceptable guideline for prevention of perioperative infection following urologic surgery, a questionnaire survey on the theory of antimicrobial prophylaxis (AMP) was conducted among urologists in Japan in February 2004. A reply was obtained from 149 urologists working for institutes located all over Japan from Hokkaido to Kyushu areas. Ninety-two percent of the urologists agreed that AMP should be administered 30 min before an incision, and 44% replied that an additional dose of AMP is required in the case of prolonged intervention. Penicillins or the 1st or 2nd generation cephems were used by 89 to 93% of the urologists in operations not including bowel segments, while 78% preferred such AMP agents in the procedures including bowel segments. AMP was terminated within 3 days in 87% for genital operations, in 70 to 76% for laparoscopic operations, in 54 to 65% for other clean or clean-contaminated operations, and in 24% for operations without the bowel segments. Especially, 58% of the urologists continued AMP for more than 5 days after operations with urinary diversion using the intestine. When compared with the previous questionnaire survey by Shinagawa et al, our survey demonstrated that standard consensus of AMP has spread widely among urologists in Japan, although the recommendations published in Europe and United States are still controversial in Japan. Thus, further well-designed clinical trials are required to establish original guidelines in Japan.

Bacterial resistance to antimicrobials in urinary isolates

Escherichia coli accounted for about 80% of organisms in uncomplicated urinary tract infections (UTIs), followed by Staphylococcus spp. especially Staphylococcus saprophyticus, and Proteus mirabilis. Against E. coli isolates from patients with uncomplicated UTI, faropenem was the most effective. Up to 1999, fluoroquinolone-resistant isolates were not observed in patients with uncomplicated UTI, but in 2001 fluoroquinolone-resistant E. coli isolates emerged and accounted for about 8%. Various types of organisms were isolated in patients with complicated UTI. Enterococcus faecalis, E. coli, and Pseudomonas aeruginosa were the three most frequent organisms isolated. These three organisms accounted for 44.6%. Amongst oral agents, faropenem showed the lowest rate of resistance against E. coli followed by cephems. The rates of highly fluoroquinolone-resistant and cefpodoxime-resistant E. coli isolates increased rapidly from 1998 to 2001. Fluoroquinolone-resistant P. aeruginosa isolates accounted for about 40% in 2001. Against this species, amikacin was the most effective antimicrobials among all agents tested. About 17% of Pseudomonas were resistant to carbapenem. Eight milligram per litre of ampicillin inhibited all E. faecalis isolates; about 60% of Enterococcus faecium were resistant to ampicillin. The rates of levofloxacin-resistant isolates of E. faecalis and E. faecium were 38 and 97% respectively. UTIs caused by vancomycin resistant enterococci (VRE) are rare in Japan.

Newer carbapenems for urinary tract infections

Four carbapenems have been available clinically in Japan. These are imipenem/cilastatin (IMIP/CS) and panipenem/ betamipron (PANI/BP) of the older compounds and newer carbapenems such as biapem (BIAP) and meropenem (MERO). The latter compounds are relatively stable to dehydropeptidase-1 (DHP-1) and have been reported to have higher antimicrobial activities compared to the earlier carbapenems. The antimicrobial activity of these four carbapenems against fresh urinary isolates showed high activities against Enterobacteriacae such as Serratia marcescens, Enterobacter cloacae, Citrobacter freundii and Escherichia coli containing the class C-beta-lactamase- and extended spectrum beta-lactamase (ESBL)-producing strains compared to piperacillin (PIPC) and ceftazidime (CTAZ). Against Pseudomonas aeruginosa, the carbapenems, with the exception of panipenem showed strong antimicrobial activities compared to PIPC and CTAZ. High activities were also seen against Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis, but methicillin-resistant strains were not affected. The first generation carbapenems showed better activity against E. faecalis than newer carbapenems. All four carbapenems were similar in clinical effectiveness in double blind trials for complicated urinary tract infections (UTIs). However, PANI/BP is less effective in UTIs caused by P. aeruginosa than IMIP/CS. MERO showed better eradication rate of P. aeruginosa than IMIP/CS. Retrospective analysis of treated cases using carbapenems showed a rapid defervescence in the treatment of febrile complicated UTIs, which were mainly caused by mixed infection of Gram-negative and Gram-positive bacteria, especially those involving P. aeruginosa and E. faecalis.

Antibiotic susceptibility of glutaraldehyde-tolerant Mycobacterium chelonae from bronchoscope washing machines

BACKGROUND

Contamination of bronchoalveolar lavage fluid is a major problem in the world. Although 2% glutaraldehyde (GA) is widely used as a disinfectant for bronchoscope cleaning, recently, GA-tolerant mycobacteria have been isolated, which makes this problem more complicated.

METHODS

We studied the susceptibility to GA and antibiotics of mycobacteria isolated from bronchoscope washing machines in our hospital. We also studied the minimum inhibitory concentrations of GA and antibiotics with pump inhibitors.

RESULTS

Twenty-nine mycobacteria were isolated, of which 26 were Mycobacterium chelonae. Among 18 isolates of M chelonae, excluding 8 isolates in which some results were not reproducible, 50% (9 of 18) were 2% GA-tolerant. One hundred percent (9 of 9) of the GA-tolerant isolates and 11% (1 of 9) of the GA-sensitive isolates were either resistant or intermediately resistant to 2 or 3 classes of antibiotics. Efflux pump inhibitors did not influence the susceptibility to GA and antibiotics.

CONCLUSIONS

It was suggested that there might be an association of GA tolerance with antibiotic resistance in M chelonae. There may a different mechanism(s) other than that involving efflux pumps with regard to GA tolerance and antibiotic resistance in M chelonae. When bronchoscopy-related mycobacterial infections are suspected, physicians and clinical microbiologists should exercise care in handling GA-tolerant mycobacteria, which may be resistant to multiple antibiotics.