Neela K. Sheth

In vitro quantitative adherence of bacteria to intravascular catheters.

Adapting standard techniques, a simple in vitro system was devised to compare quantitative bacterial adherence to iv catheters of different compositions. Upon brief immersion of catheters in suspensions of Staphylococcus aureus, coagulase-negative staphylococci, and Escherichia coli, organisms adhered to catheter surfaces. After overnight growth in broth, organisms remained adherent and formed colonies, as shown by light and scanning electron microscopy. In addition, quantitative adherence using a blood agar roll technique, expressed as bacteria per square centimeter of catheter surface area per 10(6) colonies per milliliter inoculum, was calculated. Adherence was greater on polyvinylchloride (PVC) catheters (geometric mean 342) than on Teflon catheters (geometric mean 49.6) for coagulase-negative staphylococci (P less than 0.005). Also, the number of coagulase-negative staphylococci adherent to PVC catheters was significantly greater than for E. coli (geometric mean 70.6) at analogous inocula (P less than 0.02). Differences in bacterial adherence to the surface of iv devices may be important in the pathogenesis of catheter-associated infections. This in vitro method could prove useful in testing bacterial adherence properties of newly developed catheter materials, and allow development of catheters less prone to be associated with bacterial adherence and catheter-related infections.

Epidural abscess, vertebral destruction, and paraplegia caused by extending infection from an aspergilloma

An aspergilloma developed in a lung cyst in a 53-year-old man. Aspergillus infection then contiguously spread to the epidural space, causing an abscess, vertebral destruction, and paraplegia at the level of T4. Chronic alcoholism, liver cirrhosis, and corticosteroid treatment may have been predisposing factors in this patient. Although Aspergillus epidural abscess has been described infrequently, this complication has not been described in association with an aspergilloma. Symptoms, signs, or roentgenographic or laboratory findings suggestive of vertebral or meningeal pathologic lesions in patients with aspergilloma should alert the physician to the possibility of contiguous spread of infection.

Adherence of microorganisms to breast prostheses: an in vitro study.

The quantitative and morphological characteristics of microbial adherence of four organisms—Staphylococcus epidermidis, S. aureus, Escherichia coli and Candida albicans—to the surfaces of different breast prostheses were observed. Semiquantitative adherence studies based on a modification of Makis roll culture technique even after short contact times showed (1) increased microbial adherence at higher concentrations of the organisms and (2) differences in adherence properties between gram-positive bacteria and other organisms tested, noted also at lower organism concentrations. Scanning electron microscopy (SEM) to identify microorganisms on foam-covered prostheses, however, revealed organisms in the interstitial spaces that were not recovered by the plating technique. Other features on SEM were extracellular “slime” produced by S. epidermidis, which appears to act as a cement by which bacteria are held against prosthetic surfaces. These in-vitro findings suggest that brief exposure of the prostheses to a few organisms, particularly gram-positive bacteria, at the time of implantation would be sufficient inoculum for bacterial adherence to prosthetic surfaces.

Experimental aspergillosis in rabbits.

Controls, as well as cortisone-treated rabbits, were challenged with Aspergillus fumigatus spores intratracheally. Animals were sacrificed 3, 7, 14 and 28 days after inoculation and their organs cultured and studied histologically. Lesions were produced in both groups, although the cortisone-treated group showed greater pathology and the lesions persisted for a longer period of time than the control groups. Histologically, the pulmonary lesions showed granulomatous pulmonary aspergillosis and suppurative necrotizing pneumonic infiltrates.

Tuberculous Epididymitis Occurring 35 Years After Renal Tuberculosis

An unusual case of tuberculous epididymitis occurring 35 years after renal tuberculosis is reported. The possible mechanisms of this delayed presentation of the epididymal lesion are discussed. This case emphasizes the importance of adequate treatment as well as long-term followup of patients with genitourinary tuberculosis.