[Evaluation of the Fundamental Performance of 4 Latex Agglutination Reagents to Measure Anti-TP Antibody Concentration and Detailed Investigation of Decision-Mismatched Samples].

Serological diagnosis of syphilis can be made by using the serological test for syphilis (STS) method for detecting a lipid antibody and Treponema pallidum (TP) method for detecting the anti-TP-specific antibody. In STS and TP methods, the basis using latex agglutination reaction has been used in many facilities. However, in latex agglutination, false-positive results due to non-specific reaction have sometimes been obtained in reactions of a routine laboratory test reagent detecting the anti-TP antibody used in our medical laboratory. We evaluated the fundamental performance of 4 reagents to measure anti-TP antibody concentration using latex agglutination: Reagents A, B, C and D produced by SEKISUI MEDICAL, FUJI REBIO, DENKA SEIKEN and SHINO TEST, respectively. We examined the correlations between Reagent A (routine laboratory test reagent) and Reagents B, C, and D in sera from 68 patients, and we performed additional investigation by using a neutralization test, immunochromatography, Western blotting, FTA-ABS (IgG), and STS method by an automatic analyzer for 13 decision-mismatched samples. The fundamental performance of each reagent was as good as that previously reported. Eight of the 13 decision-mismatched samples were false positives due to non-specific reaction of Reagent A. In latex agglutination non-specific reaction is inevitable. However, this study strongly suggests that using a neutralization test and immunochromatography that can be performed quickly is sufficient to verify whether positive reactions are true or false.

[Antimicrobial susceptibility of clinical isolates of aerobic Gram-positive cocci and anaerobic bacteria in 2006].

The activity of antibacterial agents against aerobic Gram-positive cocci (26 species, 1022 strains) and anaerobic bacteria (23 species, 184 strains) isolated from clinical specimens in 2006 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 53.0% and 65.8%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 micrcog/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 87.6%. Ceftriaxone, cefpirome, cefepime, carbapenem antibiotics, VCM, teicoplanin, linezolid(LZD) and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 10.9% of E. faecalis strains or 3.5% of E. faecium strains showed intermediate or resistant to LZD. 24.4% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM were under 1 microg/mL, suggesting that VCM had excellent activity against C. difficile. Carbapenems showed good activity against Peptococcaceae, Bacteroides spp., and Prevotella spp. However since several strains of Bacteroides fragilis showed resistant to carbapenems and the susceptibility of this species should be well-focused in the future.

[Antimicrobial susceptibility of clinical isolates of aerobic Gram-negative bacteria in 2006].

We determined MICs of antibacterial agents against 1280 clinical strains of aerobic Gram-negative bacteria (19 genus or species) isolated at 16 Japanese facilities in 2006. MICs were determined using mostly broth microdilution method and antibacterial activity was assessed. Strains producing extended-spectrum beta-lactamases (ESBL) accounted for 3.7% of Escherichia coli, 2.7% of Klebsiella spp., and 11.4% of Proteus spp. Notably, 18.8% of Proteus mirabilis was found to produce ESBL higher than 16.7% in 2004. This result was higher extremely than other species. Among Haemophilus influenzae, only 1.2% produced beta-lactamase and 62.8% that increased compared with 57.7% in 2004, were beta-lactamase-negative ampicillin-resistant strains when classified by penicillin-binding protein 3 mutation. Although few antibacterial agents against Pseudomonas aeruginosa have potent activity, only three agents--doripenem, ciprofloxacin, and tobramycin-showed an MIC90 of 4 microg/mL. Of all P aeruginosa strains, 5.7% were resistant to six or more agents of nine antipseudomonal agents, a decrease compared to 8.7% in 2004. Against other glucose-non-fermentative Gram-negative bacteria, the activity of most antibacterial agents was similar to that in 2004.

Recovery of susceptibility to penicillin G in clinical isolates of Streptococcus pneumoniae despite increased accumulation of pbp gene alterations.

Two hundred consecutive clinical isolates of Streptococcus pneumoniae isolated in 2005 and 2006 were analysed for susceptibility to various antimicrobials, pbp gene alterations and macrolide resistance gene expression (2007 analysis) and the results were compared with previous data (2003 analysis). The average minimum inhibitory concentration (MIC) of penicillin G in isolates with 1a(m)/2x(m)/2b(m) decreased from 1.135+/-0.503 mg/L in the 2003 analysis to 0.872+/-0.540 mg/L in the 2007 analysis (P=0.0046). The prevalence of isolates with 1a(m)/2x(m)/2b(m) increased from 30.5% to 32.3%, but the difference was not statistically significant (P=0.6979). The prevalence of isolates with a clarithromycin MIC > or = 1.0mg/L increased from 65.9% to 80.0% (P=0.0005). Isolates expressing ermB increased from 46.6% to 62.6% (P=0.0004). We conclude that the decrease in penicillin resistance of S. pneumoniae does not correlate with a decrease in pbp mutations; on the contrary, the prevalence of isolates with pbp mutations increased. A decrease in penicillin resistance in S. pneumoniae with pbp mutations appears to explain the present results regarding the recovery of penicillin susceptibility. Our results suggest that the spread of mutated pbp genes among S. pneumoniae itself is not responsible for acquisition of the penicillin-resistant phenotype. Use of beta-lactams, especially oral cephalosporins, appears to be responsible for the acquisition of penicillin resistance.

Alterations in penicillin binding protein gene of Streptococcus pneumoniae and their correlation with susceptibility patterns.

Penicillin binding protein (pbp) gene alterations of 328 clinical isolates of Streptococcus pneumoniae were examined for a correlation with their antibiotic-resistance. The frequency of penicillin G (PEN-G) resistance was determined to clarify susceptibility to several antibiotics, namely PEN-G, ampicillin, sulbactam/ampicillin, cefozopram, panipenem (PAPM), clarithromycin (CLR), azithromycin (AZM) and levofloxacin (LVX). Oligonucleotide primers for three pbp genes (pbp1a, pbp2x and pbp2b) were used to detect mutations in pbp. Of the strains, 25.9% were classified as Pen-Gs, 68.0% as Pen-Gir and 6.1% as Pen-Gr. The polymerase chain reaction product for wild-type pbp1a was found in 185 isolates, that for wild-type pbp2x was found in 66 isolates and that for wild-type pbp2b was found in 213 isolates. None of these three genes was detectable in 100 isolates while all of them were detected in 64 isolates (1aw/2xw/2bw). Of those 64 isolates with 1aw/2xw/2bw, the minimum inhibitory concentration (MIC) of PEN-G was < or =0.06 mg/l for 54 isolates and 0.12 mg/l for 10 isolates. Of the 272 strains for which the MIC of PAPM was < or =0.03 mg/l, there were 85 Pen-Gs, 184 Pen-Gir and three Pen-Gr isolates. Three strains for which the MIC of LVX was > or =4.0 mg/l included one Pen-Gs and two Pen-Gir isolates. The MICs of CLR correlated significantly with those of AZM. The MIC of CLR was > or =1 mg/l for 216 isolates, and the MIC of AZM was > or =1 mg/l for 244 of them. These data suggested that PAPM may be effective against S. pneumoniae infection, although acquisition of resistance should be considered. LVX also seemed to be effective against S. pneumoniae.

Undetected Bacillus pseudo-outbreak after renovation work in a teaching hospital.

A 602-bed capacity hospital underwent complete renovation from 1999 to 2004. In April 2005, the Infection Control Team was informed of the occurrence of three consecutive cases of Bacillus cereus bacteremia in a ward for patients with hematologic malignancies. A retrospective analysis of patients with Bacillus isolates was initiated. We found more Bacillus cereus isolates from blood samples in 2004 compare to the preceding years. Swab samples were collected in the particular ward from the surface of a working desk, filter unit of the air-conditioners, entrance of air inlet ducts, exit of the air outlet ducts and three-way valves of the particular ward under the consideration of iatrogenic contamination. Towels and gowns used in the ward were examined. Dens dust was noted in the filter of the air-conditioner and inlets/outlets of the air-ventilation system of the ward. Bacillus cereus was isolated from the dust, and from cleaned towels and gowns. PFGE fingerprinting differed among four patients' sample. We considered the present case as an undetected Bacillus cereus pseudo-outbreak that lasted for about one year after the renovation work of the hospital. We also considered that filters of the HVAC-system and towels and gowns were probable sources of the outbreak.

Limitations in the use of rifampicin-gelatin grafts against virulent organisms.

OBJECTIVE: Efficacy and duration of antibacterial activity of rifampicin-gelatin grafts against virulent organisms were evaluated in an animal model. MATERIALS AND METHODS: Rifampicin-gelatin grafts were prepared with impregnation of Gelseal (Vascutek Ltd, Scotland) graft in 1 mg/mL rifampicin solution. Rifampicin-gelatin grafts (6 cm long; n = 24) and plain Gelseal grafts as controls (n = 4) were implanted into the canine abdominal aorta with inoculation of Staphylococcus epidermidis, Escherichia coli, or methicillin-resistant Staphylococcus aureus (MRSA), and the rifampicin-gelatin grafts were retrieved after 1 to 4 weeks. Disks cut from the retrieved rifampicin-gelatin grafts were placed on agar plates streaked with one of the organisms, and the graft antibacterial activity was assessed with the width of the inhibition zone. RESULTS: In in vitro tests, initial inhibition zones (inhibition zone of 24 hours after incubation) of rifampicin-gelatin grafts against S epidermidis, MRSA, and E coli were 40.0 +/- 0.3 mm, 36.0 +/- 0.2 mm, and 11.8 +/- 0.1 mm, respectively. In the implantation, S epidermidis -inoculated rifampicin-gelatin grafts had no findings of graft infection, and no colony growth was recognized on the plates streaked with the perigraft fluids. Initial inhibition zones of S epidermidis -inoculated rifampicin-gelatin grafts retrieved at 1 or 2 weeks were 20.1 +/- 1.1 mm and 7.6 +/- 1.0 mm, respectively. In E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts, all of the eight animals had perigraft abscess, and blood culture test results probed septicemia in five animals with patent grafts at death. Inhibition zones against E coli or MRSA were not formed on the plates streaked with the same organism, whereas initial inhibition zones of E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts on S epidermidis -streaked plates were 8.0 +/- 0.2 mm and 18.5 +/- 0.5 mm, respectively. In the MRSA group, however, recolonization of high minimal inhibitory concentration strains developed within the inhibition zones as early as 24 hours. Histologically, neither organisms nor inflammatory cells were found in S epidermidis -inoculated rifampicin-gelatin grafts and tissue ingrowth was recognized at 2 to 4 weeks, whereas E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts had aggressive neutrophil infiltration into the graft interstices, revealing establishment of uncontrollable graft infection. CONCLUSION: These results suggested that rifampicin-gelatin grafts are clearly valid for S epidermidis infection, whereas no efficacy was recognized against either MRSA or E coli graft infection because of early development of high minimal inhibitory concentration MRSA strains or poor susceptibility.