Infections after PRK could have a happy ending: a series of three cases.

BACKGROUND: Infectious keratitis after PRK remains a rare but potentially devastating complication. HISTORY AND SIGNS: Medical records of 3 male patients with infectious keratitis after uneventful PRK for myopia and astigmatism were reviewed retrospectively. PRK was performed using the Wavelight Allegretto excimer laser. Postoperative care included a bandage contact lens (BCL) for 5 days, topical antibiotics, ketorolac, and artificial tears. THERAPY AND OUTCOME: Keratitis presented 2 - 4 days postoperatively. In one case, each culture was negative (case 1), and was positive for Streptococcus pneumoniae (case 2) and Staphylococcus aureus (case 3). Final BSCVA (best spectacle corrected visual acuity) after intensive antibiotic treatment and removal of BCL were 1.0 (case 1), 0.9 (case 2) and 0.3 correctable to 0.8 with pinhole (case 3). CONCLUSIONS: Postoperative broad-spectrum antibiotics are mandatory after PRK to prevent infectious keratitis. However, resistant organisms are more and more common. The presence of a bandage soft contact lens after surgery is an unfavourable element that may increase risk of infection. Based on our case series, we suggest limiting soft contact lens wear during the two postoperative days even if the corneal ulceration is not healed.

Granular layer in the periplasmic space of gram-positive bacteria and fine structures of Enterococcus gallinarum and Streptococcus gordonii septa revealed by cryo-electron microscopy of vitreous sections.

High-resolution structural information on optimally preserved bacterial cells can be obtained with cryo-electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus was recently shown. This raises questions about the mode of polymerization of peptidoglycan. In the present study, we report the structure of the cell envelope of three gram-positive bacteria (B. subtilis, Streptococcus gordonii, and Enterococcus gallinarum). In the three cases, a previously undescribed granular layer adjacent to the plasma membrane is found in the periplasmic space. In order to better understand how nascent peptidoglycan is incorporated into the mature peptidoglycan, we investigated cellular regions known to represent the sites of cell wall production. Each of these sites possesses a specific structure. We propose a hypothetic model of peptidoglycan polymerization that accommodates these differences: peptidoglycan precursors could be exported from the cytoplasm to the periplasmic space, where they could diffuse until they would interact with the interface between the granular layer and the thick peptidoglycan layer. They could then polymerize with mature peptidoglycan. We report cytoplasmic structures at the E. gallinarum septum that could be interpreted as cytoskeletal elements driving cell division (FtsZ ring). Although immunoelectron microscopy and fluorescence microscopy studies have demonstrated the septal and cytoplasmic localization of FtsZ, direct visualization of in situ FtsZ filaments has not been obtained in any electron microscopy study of fixed and dehydrated bacteria.

Concentrations plasmatiques et articulaires pendant l'administration de céfacétrile pour arthrite septique (6 cas) [Serum and joint levels of cefacetrile during its administration for septic arthritis]

Six patients, five of whom had normal and one impaired renal function, and all suffering from purulent arthritis caused by cephalosporin-sensitive germs, were given a seven-day course of 8 g cephacetrile daily. On the first day, 6 g were administered by continuous intravenous infusion at the rate of 500 mg/h, followed by 2 g over a further 45 min. On days 2 to 7, the patients received 2 short infusions of 4 g each at an interval of 12 h. In four patients with normal renal function, serum half-life ranged from 0.8 to 1.4 h, serum levels during continuous infusion from 19 to 31 microgram/ml, and total clearances from 265 to 434 ml/min. In one patients, these values were 1.6 h, 70 microgram/ml and 131 ml/min respectively (small volume of distribution). The concentrations in the synovial fluid varied from 2 to 29 mcirogram/ml; they were generally lower than the serum levels, but clearly exceeded the minimum inhibitory concentrations for germs commonly present in purulent arthritis. In five patients, the synovial fluid became germ-free and the arthritis was clinically cured. In the case presenting with renal insufficiency, the serum half-life was 5.8 h. During continuous administration, a steady state was not attained; peak serum levels amo9nted to 75 microgram/ml and the total clearance to 61 ml/min. The cephacetrile concentrations in the synovial fluid were very high (26 and 67 microgram/ml). In this case, in which the renal insufficiency associated with mycosis fungoides was present before the treatment, renal function deteriorated futher during treatment while the arthritis improved.

Experimental bacterial endocarditis after dental extractions in rats with periodontitis.

The development of bacterial endocarditis was analyzed after dental extractions in rats with or without periodontal disease. Periodontal disease was produced in rats by tying silk ligatures around the two maxillary first molars and placing the animals on a high sucrose diet for 14 weeks. Sterile aortic valve vegetations were produced by means of a transaortic catheter, and 24 hr later the maxillary first molars were extracted. The animals were killed 72 hr after the extractions. In rats with periodontal disease, extractions resulted in a 48% (14 of 29) incidence of bacterial endocarditis, most cases of which were due to Streptococcus spp. (one was caused by Staphylococcus aureus). In contrast, when the teeth with a healthy periodontium were extracted, only 6% (one of 15) of the rats developed endocarditis. When catheters were placed in animals with periodontal disease but no extractions were performed, no endocarditis occurred.