Methicillin resistance of bacteria isolated from vitreous fluid from patients undergoing vitrectomy.

PURPOSE: The aim of this study was to compare the resistance patterns of bacteria in vitreous fluid from patients undergoing vitrectomy for diagnostic reasons, with bacteria of other nosocomial infections. METHODS: Vitreous fluid samples (n=144) were obtained from 133 patients undergoing vitrectomy for endophthalmitis, and 11 for uveitis as suspected endophthalmitis. They were Gram stained and cultured. Antibiotic susceptibility tests were run on all isolates. RESULTS: Gram stains were positive in 45/144 cases (31%), among which 38/45 (84%) were confirmed by a positive culture. Cultures were positive in 74/144 patients (51%) with mainly coagulase-negative staphylococci (n = 44) and Staphylococcus aureus (n = 13). In 133 patients endophthalmitis occurred after lens implantation (80 cases) and in 53 cases there was another origin (e.g. corneal transplantation, endogenous). In 26/80 post-lens implantation infections, culture remained negative; 32 infections occurred with coagulase-negative staphylococci, 10 with Staphylococcus aureus, 9 with streptococci and 3 with gram-negative bacteria. For endophthalmitis, ophthalmologists in our institution give an intraocular injection of vanccmycin and ceftazidim after vitrectomy. Among the 44 isolates of coagulase-negative staphylococci, 12 (27%) were resistant to methicillin. This is in contrast to other hospital-related coagulase-negative staphylococcus infections in general, and the resistance rate is 75% in our hospital. Only 2/13 Staphylococcus aureus isolates were methicillin-resistant. CONCLUSIONS: We conclude that isolates of coagulase-negative staphylococci from vitreous fluid are less resistant to methicillin than those isolated in other nosocomial infections.

A simple and efficient urine sampling method for bacteriological examination in elderly women.

AIM: to determine how collecting urine voided directly into a container compares with urine obtained by suprapubic aspiration. METHOD: urine samples were collected in a sterile recipient placed in the toilet or in the bed-pan during voiding, after the vulval region had been cleaned by water. These samples were compared with samples of the same urine obtained by suprapubic aspiration. The samples were examined for pyuria and bacteriuria. Applying the Kass criteria on the voided urine specimen and assessing the presence of leucocyturia, it was possible to differentiate urinary tract infection, asymptomatic bacteriuria and contamination. RESULTS: all 13 cases of infection found on suprapubic aspiration were also identified by this sampling technique. The technique produced four false-positive results. CONCLUSION: this simple sampling method may not only obviate the need for suprapubic aspiration but also for bladder catheterization in the diagnosis of urinary tract infection in many elderly women.

Scanning electron microscopy of dentin caries. Experimental in vitro studies with Streptococcus mutans.

This study was performed to gain better insight into the mechanisms involved in carious destruction of human dentin by Streptococcus mutans. In particular, bacterial colonization of dentin surfaces and bacterial invasion in dentin were studied. Streptococcus mutans (S. mutans), strain NCTC 10449, was grown on sterile dentin blocks in a 10% CO2 atmosphere at 37 degrees C. After 72, 120, 144 and 288 h of incubation the specimens were processed for scanning electron microscopic examination. The colonization of the dentinal surface progressed slowly and was nearly complete after 288 h. Invasion of S. mutans into the dentinal tubules was found occasionally and was limited to the initial 5 micron of the tubular lumen. The acid metabolites produced by S. mutans, caused lesions of the dentinal structures in the close proximity of the bacteria. From the results of this in vitro study it appears that carious destruction of exposed dentinal surfaces by S. mutans mainly occurs at the exposed dentin after it has been colonized by bacteria. Destruction of the deeper dentinal layers by bacteria invading the dentinal tubules may play a less important role. However, in the few cases where S. mutans invaded the dentinal tubules, rapid destruction of the peritubular dentin sheath occurred. In addition, the possibility remains that acid metabolites produced by S. mutans diffuse into the dentinal tubules and cause tissue damage in the deeper parts of the dentin.