Review Article Invasiveness of Pseudomonas aeruginosa and Its Role in Diversity of Pseudomonal Infectious Diseases

Pseudomonas aeruginosa causes both invasive (bacteremic) and chronic non-invasive infections in several organs, resulting in the diversity of infectious diseases. When Madin- Darby canine kidney (MDCK) monolayers were infected with clinical isolates of P. aeruginosa, significantly (P < 0.001) more blood (30 of 32, 93.7%) than respiratory (25 of 45, 54.4%) isolates penetrated the epithelial cell monolayers by 3 h. Only eight (4 blood and 4 respiratory) isolates were cytotoxic and possessed exo U, and passed through the monolayer following epithelial cell death associated with release of lactose dehydrogenase and a marked drop in transepithelial electrical resistance. Thus, invasiveness was usually independent of cytotoxicity. The capacity to penetrate epithelial cells appears to be a critical determinant of invasiveness in susceptible hosts and may be controlled by unknown unique genes. In addition, such invasion determinant(s) are thought to be predominantly exported by P. aeruginosa via MexAB-OprM, which is one of multi-drug resistant (MDR) efflux systems. Hence, MDR efflux systems in P. aeruginosa might be critical for the efflux of virulence factors, in addition to their established role of exporting harmful substances such as antibiotics or detergents

Comparison of Four Carbapenems; Imipenem-Cilastatin, Panipenem-Betamipron, Meropenem, and Biapenem with Review of Clinical Trials in Japan

The development of carbapenem gives a revolutionary impact to the chemotherapy of infectious diseases. The bacteriological and clinical efficacies of carbapenems, including imipenem/cilastatin, panipenem/betamipron, meropenem and biapenem, were evaluated. All four carbapenems were potent against gram-positive and gram-negative bacteria except Stenotrophomonas maltophilia. The antimicrobial activities of meropenem against Enterobacteriaceae were slightly superior to other carbapenems. Imipenem and panipenem were slightly more active against gram-positive bacteria than meropenem and biapenem. Biapenem was the most potent against Acinetobacter anitratus. The in vitro activity of imipenem was compared between 1990 and 1992 in Nagasaki University Hospital. The resistance rate of S. aureus, whose MIC is higher than 25 mg/l, increased from 3% to 22%, S. pneumoniae, whose MIC is higher than 0.05 mg/l, increased from 9% to 30% and P. aeruginosa, whose MIC is higher than 5 mg/l, increased from 20% to 32%. The isolation rates of S. maltophilia from sputum increased gradually from 0.9% in 1984 to 3.5% in 1991. The clinical efficacy rates of imipenem/cilastatin and panipenem/betamipron were 79% and 77%, and the rates of meropenem and biapenem 100% and 96.2% for the treatment of respiratory infection in our department, respectively. The efficacy rates of imipenem/cilastatin decreased from 79% to 67.7% after being commercialized. This decline was due to administration to patients with severe underlying diseases and with infection caused by resistant strains such as P. aeruginosa and S. aureus. The phase II and III trials of carbapenems in internal medicine, which were performed separately in Japan, showed that the clinical efficacy rates were 73%, 79%, 86% and 89%, and the rates of adverse reaction were 4.7%, 3.3%, 1.8% and 2.2% in imipenem /cilastatin, panipenembetamipron, meropenem and biapenem, respectively. Newly develope

Multidrug Efflux Systems Play an Important Role in the Invasiveness of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an important opportunistic human pathogen. Certain strains can transmigrate across epithelial cells, and their invasive phenotype is correlated with capacity to cause invasive human disease and fatal septicemia in mice. Four multidrug efflux systems have been described in P. aeruginosa, however, their contribution to virulence is unclear. To clarify the role of efflux systems in invasiveness, P. aeruginosa PAO1 wild-type (WT) and its efflux mutants were evaluated in a Madin-Darby canine kidney (MDCK) epithelial cell monolayer system and in a murine model of endogenous septicemia. All efflux mutants except a ΔmexCD-oprJ deletion demonstrated significantly reduced invasiveness compared with WT. In particular, a ΔmexAB-oprM deletion strain was compromised in its capacity to invade or transmigrate across MDCK cells, and could not kill mice, in contrast to WT which was highly invasive (P < 0.0006) and caused fatal infection (P < 0.0001). The other mutants, including ΔmexB and ΔmexXY mutants, were intermediate between WT and the ΔmexAB-oprM mutant in invasiveness and murine virulence. Invasiveness was restored to the ΔmexAB-oprM mutant by complementation with mexAB-oprM or by addition of culture supernatant from MDCK cells infected with WT. We conclude that the P. aeruginosa MexAB-OprM efflux system exports virulence determinants that contribute to bacterial virulence

Prevalence of Antimicrobial Resistance in Haemophilus influenzae and Streptococcus pneumoniae : Comparison of Clinical Isolates of Japan and The Philippines

For clinical isolates of Haemophilus influenzae and Streptococcus pneumoniae in Japan (356 and 179 strains, respectively) and in the Philippines (98 and 59 strains, respectively), minimum inhibitory concentrations (MICs) of ampicillin, cefazolin, cefotiam, ceftizoxim, ofloxacin, erythromycin, and minocycline were examined. The rates of β-lactamase producing H. influenzae were 17.7% (63/356) in Japan and 2.0% (2/98) in the Philippines, and all of these strains were ampicillin MICs 〓1.56 ugml^. In addition, 5 strains in Japan that lacked β-lactamase activity were also less susceptible to ampicillin. Among the antimicrobials tested, ceftizoxim was the most active against H. influenzae in both countries (MICs 〓0.2 ugml^). Five strains of S. pneumoniae in Japan were relatively resistant to ampicillin (MIC=0.1 ugml^), whereas there were no such strains among isolates in the Philippines. Forty strains (22.3%) and 108 strains (60.3%) among S. pneumoniae in Japan exhibited erythromycin MICs 〓0.2 ugml^ and minocycline MICs 〓1.56 ugml^, respectively. In contrast, all isolates in the Philippines were erythromycin MICs 〓0.05 ugml^ and minocycline MICs 〓0.39 ugml^. Present study indicates that H. influenzae and S. pneumoniae in the Philippines remained still susceptible to the antimicrobials tested except for 2 β-lactamase-positive, ampicillin-resistant H. influenzae, whereas ampicillin-resistant H. influenzae mediated by β-lactamase or non-β-lactamase mechanisms and ampicillin-, erythromycin- or minocycline-resistant S. pneumoniae were included among isolates in Japan

Molecular Characteristics of Extended-Spectrum Beta-Lactamases and qnr Determinants in Enterobacter Species from Japan

The incidence of extended-spectrum β-lactamases (ESBLs) has been increasing worldwide, but screening criteria for detection of ESBLs are not standardized for AmpC-producing Enterobacteriaceae such as Enterobacter species. In this study, we investigated the prevalence of ESBLs and/or AmpC β-lactamases in Japanese clinical isolates of Enterobacter spp. and the association of plasmid-mediated quinolone resistance (PMQR) determinants with ESBL producers. A total of 364 clinical isolates of Enterobacter spp. collected throughout Japan between November 2009 and January 2010 were studied. ESBL-producing strains were assessed by the CLSI confirmatory test and the boronic acid disk test. PCR and sequencing were performed to detect CTX-M, TEM, and SHV type ESBLs and PMQR determinants. For ESBL-producing Enterobacter spp., pulsed-field gel electrophoresis (PFGE) was performed using XbaI restriction enzyme. Of the 364 isolates, 22 (6.0%) were ESBL producers. Seven isolates of Enterobacter cloacae produced CTX-M-3, followed by two isolates producing SHV-12. Two isolates of Enterobacter aerogenes produced CTX-M-2. Of the 22 ESBL producers, 21 had the AmpC enzyme, and six met the criteria for ESBL production in the boronic acid test. We found a significant association of qnrS with CTX-M-3-producing E. cloacae. The 11 ESBL-producing Enterobacter spp. possessing blaCTX-M, blaSHV, or blaTEM were divided into six unique PFGE types. This is the first report about the prevalence of qnr determinants among ESBL-producing Enterobacter spp. from Japan. Our results suggest that ESBL-producing Enterobacter spp. with qnr determinants are spreading in Japan

Multiprefectural Spread of Gastroenteritis Outbreaks Attributable to a Single Genogroup II Norovirus Strain from a Tourist Restaurant in Nagasaki, Japan

A series of gastroenteritis outbreaks caused by noroviruses (NVs) among tourist groups from several prefectures was associated with eating a lunch prepared by a restaurant in Nagasaki City, Japan, on 18 and 19 November 2003. A retrospective cohort study was performed to estimate the magnitude of the outbreak and identify the source of infection. Epidemiological information was obtained through the local public health centers in the areas where the illness occurred. Stool and vomit specimens and food and environmental samples were analyzed by reverse transcription-PCR with genogroup-specific primers. Positive samples were sequenced and analyzed phylogenetically. Of 1,492 tourists who ate a lunch prepared by the restaurant during the 2-day period, 660 (44.2%) developed illness, with an average incubation time of 31.2 h. Whereas NVs were not detected in any food samples, identical sequences most closely related to the Mexico genotype of genogroup II NV were found in specimens from case patients, restaurant staff, and the kitchen table. Food handlers were concluded to be the source of the outbreak as a result of the contamination of several meals. The series of outbreaks described here exemplifies the role of tourism as a contemporary way to distribute a single infectious agent to multiple and geographically remote areas