Journal of medical microbiology
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Comparative Study Clinical Trial
Long-term effects on the nasopharyngeal flora of children following antimicrobial therapy of acute otitis media with cefdinir or amoxycillin-clavulanate.
The effect on the nasopharyngeal bacterial flora of 10 days of amoxycillin-clavulanate or cefdinir antimicrobial therapy was studied in 50 children with acute otitis media. Before therapy, 17 potential pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) were isolated from the nasopharynx of 14 (56%) of those treated with amoxycillin-clavulanate, and 20 potential pathogens were recovered from 15 (60%) of those treated with cefdinir. Following therapy, at days 12-15, the number of potential pathogens was reduced to a similar extent with both therapies, to three in those treated with amoxycillin-clavulanate and two in those treated with cefdinir. ⋯ This study illustrates the potential beneficial effect of using a narrow-spectrum antimicrobial that selectively spares the interfering organisms while eliminating pathogens. The benefit of such therapy is the prevention of reacquisition of pathogenic bacteria in the nasopharynx. In contrast, utilization of a broad-spectrum antimicrobial is associated with prolonged absence of inhibitory organisms and rapid recolonization with pathogens.
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Many antiseptic agents are used in hygienic handwashes in the prevention of nosocomial infections by methicillin-resistant Staphylococcus aureus (MRSA). The plasmid-borne genes qacA/B and smr confer resistance to cationic antiseptic agents in S. aureus. In this study, the susceptibilities for dyes and antiseptic agents (e.g. acriflavine, acrinol, benzalkonium chloride, benzethonium chloride, chlorhexidine digluconate and alkyldiaminoethylglycine hydrochloride) of 894 isolates of MRSA collected from 11 Asian countries (South Korea, China, the Philippines, Singapore, Vietnam, Thailand, Indonesia, India, Sri Lanka, Saudi Arabia and Japan) between 1998 and 1999 were examined. ⋯ MRSA with qacA/B comprised 41.6% (372/894) of the isolates across Asia. In addition, PFGE was performed to type the MRSA and grouped the tested 30 MRSA isolates with qacA/B into 21 PFGE types. The results indicated that qacA/B is functionally the most important gene mediating antiseptic resistance in the MRSA strains of Asia and that a specific MRSA with qacA/B was not prevalent in Asia but qacA/B were widely spread among MRSA of Asia, while the geographical distribution of smr is more limited.
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Comparative Study
Genotypic and phenotypic characteristics of Pseudomonas aeruginosa isolates associated with ulcerative keratitis.
A collection of 63 isolates of Pseudomonas aeruginosa associated with ulcerative keratitis, collected from six centres in England, were typed using serotyping and random amplified polymorphic DNA-PCR, and screened for several variable virulence-related genotypes and phenotypes. Sixty-one percent of the isolates were of either serotype O1 or serotype O11, but there was no evidence for a common clone. ⋯ All but one of the isolates exhibited twitching activity. There was a correlation between the presence of exoS and twitching activity (P = 0.04), suggesting that a combination of exoS genotype and good twitching activity may have a role to play in ExoU-independent corneal virulence.
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The role of quorum-sensing systems in a mouse model of chronic Pseudomonas aeruginosa infection was studied. A chronic P. aeruginosa respiratory infection model was established by placement of a tube pre-coated with strain PAO1 (wild-type) or a quorum-sensing mutant, namely PAO-JP1 (Delta lasI), PDO100 (Delta rhlI) or PAO-JP2 (Delta lasI/Delta rhlI), in the bronchus. ⋯ In the bronchoalveolar lavage fluid from the quorum-sensing-system-mutant groups the proportion of neutrophils was lower than in wild-type group. These findings indicate that the quorum-sensing system plays an important role in chronic P. aeruginosa respiratory infection.
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The objective of this study was to investigate the antimicrobial susceptibility of the organisms isolated from the nasopharynx of children who presented with acute otitis media (AOM) or otitis media that recurred after amoxicillin therapy. Nasopharyngeal cultures obtained from 72 patients, 40 with AOM and 32 with recurrent otitis media (ROM), were analysed. Thirty-six potentially pathogenic organisms were recovered in 34 (85 %) of the children from the AOM group, and 42 were isolated from 29 (91 %) of the children from the ROM group. ⋯ Resistance to the eight antimicrobial agents used was found in 37 instances in the AOM group as compared to 99 instances in the ROM group (P < 0.005). The difference between AOM and ROM was significant with Streptococcus pneumoniae resistance to amoxicillin (P < 0.005), to amoxicillin/clavulanate (P < 0.005), to trimethoprim/sulfamethoxazole (P < 0.01), to cefixime (P < 0.01) and to azithromycin (P < 0.01), and for H. influenzae resistance to amoxicillin (P < 0.025). These data illustrate the higher recovery rate of antimicrobial-resistant Streptococcus pneumoniae and H. influenzae from the nasopharynx of children who had otitis media that recurred after amoxicillin therapy than those with AOM.