Corneal ulcer disease in Bangladesh

The problem of acute infectious corneal disease in Bangladesh is discussed. Environmental situations combined with socioeconomic conditions create significant blindness due to this disease in this country. Clinical differentiation into bacterial and fungal ulcers was usually impossible in the advanced stages of ulceration with which the patients presented. Serious logistical problems hinder therapy. Fungal ulcers fared worse than bacterial ulcers. Conjunctival flaps were unsuccessful in alleviating the former. Critical shortage of medication as well as corneal tissue for therapeutic transplantation added to the difficulties. Large-scale public health and educational measures are indicated for effective, long-term solution.

Tympanostomy tubes and otic drops

Otic drops have been proposed as a form of prophylaxis against the otitis media which follows middle ear contamination by water in patients with tympanostomy tubes. The potential adverse effects of this form of therapy were studied in chinchillas with tympanostomy tubes; 31 chinchillas underwent bilateral tympanostomy tube insertion. Seven animals had a mixture of green dye and Cortisporin otic suspension placed in both external auditory canals 24 hours following the placement of tympanostomy tubes and were sacrificed 30 minutes later for gross examination; 3 of these animals had previous eustachian tube obstruction with Silastic sponge. Twenty-one animals had Cortisporin otic suspension placed in the right external auditory canal on postoperative days 3, 4, 5, 6 and 7. No otic drops were placed in the left ear. Ten of these 20 animals had VIIIth nerve action potentials measured on postoperative day 17 and the other 11 animals had VIIIth nerve action potentials measured on postoperative day 42 followed by immediate sacrifice for histological examination and scanning electronmicroscopy. The remaining 3 animals had VIIIth nerve action potentials measured 21 days following tympanostomy tube insertion and served as electrophysiological controls. The 8 ears receiving Cortisporin otic drops mixed with green dye from animals with normal eustachian tubes showed staining of the round window membrane at sacrifice, while the 6 ears receiving Cortisporin otic suspension and green dye from animals with eustachian tube obstruction demonstrated no dye in the middle ear. All animals receiving Cortisporin otic drops in the right ear showed an intra-aural difference in action potentials with the right ear being attenuated by an average of 10.3 dB at 2,000 Hz, 12 dB at 4,000 Hz, 21 dB and 8,000 Hz, and 26 dB at 12,000 Hz. Morphological study revealed hair cell loss in the hook portion of the cochlea in those animals receiving Cortisporin otic drops. It was concluded from this study that, in patients with patent tympanostomy tubes in place, potentially ototoxic topical agents should be used with caution.

Novel mucosal anti-microbial functions interfering with the plasmid-mediated virulence determinants of adherence and drug resistance

Mucosal antibodies in vivo and in vitro interfere with the stability of plasmids coding for important virulence determinants in porcine enteropathogenic E. coli (EEC), such as the adhesion determinants K88ab and K88ac. The effector antibody is not directed against K88 antigens and is not serotype specific, but an antigen common to K88+ strains is implicated. Further lack of pathogen specificity is exemplified by antibody elimination of the more recently discovered K88ad plasmid. Antibodies that interfere with K88 plasmids do not affect K99, which now appears as an alternative adhesion factor in porcine enteropathogenic E. coli. This plasmid can be eliminated, however, by antibodies having K99 specificity. In extending the studies to drug-resistance plasmids, further evidence has emerged that mucosal antibodies may assist in host control of the reservoir of R factors in the intestinal microflora. A major effector mechanism is that secretory IgA and IgM antibodies from orally immunized pigs can block the transfer of R factors between donor and recipient strains of E. coli.

Prophylactic antibiotics in elective colorectal surgery

In an effort to determine whether or not the addition of parenteral antibiotics to orally administered erythromycin and neomycin would diminish postoperative septic complications in elective colorectal operations, a randomized, double-blind, controlled trial was conducted comparing three groups. All patients received vigorous preoperative mechanical bowel preparation, 3 g erythromycin and 3 g neomycin orally, the day prior to operation. Patients in Group O received three doses of saline intravenously as placebo, patients in Group C received cefazolin, 1 g, immediately preoperatively and 1 g every 6 hours postoperatively, intravenously, for two doses, and patients in Group T received a single immediate preoperative dose of 6 g of ticarcillin intravenously and two saline placebo doses intravenously, postoperatively. The patients' progress was followed in the hospital and for one month postoperatively. Septic complications occurred in 35 per cent of patients in Group O, 7 per cent of patients in Group C, and 5 per cent of patients in Group T. Wound infections comprised most of these complications, occurring in 29 per cent of Group O, 4.7 per cent of Group C, and 2.3 per cent of Group T patients. Thus, the addition of either parenteral cefazolin or ticarcillin in this study significantly reduced wound infections in elective colorectal surgery.

Ototoxicity of oral neomycin and vancomycin

In contrast to parenteral neomycin, which may result in severe and progressive ototoxicity, oral neomycin has been widely used for 25 years, and its index of safety has been regarded as high. Ototoxicity is viewed as an uncommon complication of oral neomycin most likely to occur in patients with renal failure or gastrointestinal inflammation. Two cases of ototoxicity resulting from oral neomycin are presented. Serial audiometric and neomycin blood level testing are suggested as a means of auditory monitoring in patients receiving the drug. A review of experience with oral vancomycin indicates that this drug has not been shown to cause ototoxicity.

Enhancement of nadolol elimination by activated charcoal and antibiotics

This study was carried out to assess whether nadolol undergoes enterohepatic circulation. Eight healthy subjects received 80 mg nadolol orally on three occasions at least 2 wk apart. The first experiment was a control. The second consisted of nadolol followed in 3 hr by 3 gm activated charcoal given over a 9-hr period. In the third, the subjects received 0.5 gm erythromycin base and 0.5 gm neomycin four times a day orally for 2 days before nadolol. After the activated charcoal, the nadolol AUC fell from 2455 +/- 155 to 1355 +/- 123 ng . hr/ml (mean +/- SE), as did the percentage nadolol recovered in urine (15.4 +/- 1.4 to 10.2 +/- 0.7%) and the nadolol t1/2 (17.3 +/- 1.7 to 11.8 +/- 1.6 hr). These data suggest that nonrenal elimination increased. After the antibiotics, nadolol AUC was constant, percentage of nadolol recovered in urine fell to 12.7 +/- 1.7%, nadolol t1/2 fell to 11.6 +/- 1.3 hr, and mean peak nadolol concentration rose from 146 +/- 15 to 397 +/- 52 ng/ml. These results suggest that there is an enterohepatic circulation for nadolol, that activated charcoal may decrease nadolol bioavailability, and that antibiotics may increase the nadolol effect.

Efficacy of oral and systemic antibiotic prophylaxis in colorectal operations

A cooperative Veterans Administration study of the septic complication rate during large-bowel surgery was undertaken in two groups of patients. The first group received oral neomycin and erythromycin base plus parenteral placebo; the second, the oral antibiotics plus parenteral cephalothin sodium. During a five-year period, 1,128 patients were studied. The overall septic complication rate was 7.8% in patients receiving only oral antibiotics, and 5.7% in patients receiving both oral and parenteral antibiotics. This difference was not significant. The only significant finding was a greater incidence of fever of unknown origin in patients receiving only oral antibiotics. None of those patients were treated with additional antibiotics, and all fevers cleared spontaneously. There seems to be no discernible benefit from adding parenteral antibiotic prophylaxis when performing elective colon surgery if appropriate mechanical cleansing and oral neomycin and erythromycin therapy are employed.

Biocidal braided sutures

Once sutures become contaminated it is difficult for local tissue defenses or antibiotics to eliminate the bacteria and prevent infection. Impregnation of sutures with antibiotics before implantation is one way to prevent bacterial seeding of the suture surface. In this study, braided silk and Dacron sutures were impregnated with the antibiotic complex, neomycin palmitate. Using our standard wound model in the mouse, the efficacy of these biocidal sutures was determined in the presence of Staphylococcus aureus, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa. Implantation of these biocidal sutures into tissue contaminated with 10(7) organisms resulted in substantially decreased numbers of bacteria as compared with that of tissue receiving control sutures. In most cases, the tissue bacterial counts in the presence of biocidal sutures were also considerably lower than that for similarly contaminated tissue without a suture. Consequently, the presence of the neomycin palmitate eliminated the infection-potentiating effect of the suture. The therapeutic benefit of the biocidal sutures was related to the dose of antibiotic complex and was not adversely affected by delaying suture implantation.

Prophylactic antibiotics in colon surgery

One hundred twenty-three patients undergoing elective colon surgery were prospectively and randomly assigned to receive either three 1-g perioperative doses of intramuscular cephaloridine or three 1-g preoperative doses of both oral erythromycin base and neomycin sulfate. All patients had their bowels thoroughly cleansed mechanically. The groups were comparable in age and nutritional status. Eight wound infections occurred in the 65 patients receiving cephaloridine (12.3%) v one in the 58 receiving erythromycin and neomycin (1.7%). The difference was statistically significant. Eight of nine infected patients had only wound infections; the majority of cultures yielded Bacteroides fragilis. Serum and tissue antimicrobial concentrations were determined in the first 70 randomized patients at operation. Mean (+/- SD) cephaloridine levels were 14.7 +/- 10.2 and 10.5 +/- 10.0 mg/L in serum and tissue, respectively, compared with 1.98 +/- 1.58 and 0.699 +/- 1.146 mg/L for serum and tissue erythromycin levels.

Evaluation of daily meatal care with poly-antibiotic ointment in prevention of urinary catheter-associated bacteriuria

Meatal care with a poly-antibiotic ointment twice daily was evaluated in a prospective, randomized, controlled study of patients with temporary indwelling urethral catheters. Bacteriuria was acquired in 14 of 214 patients treated (6.5 per cent), compared to 16 of 214 patients not given treatment (7.5 per cent). The rate of bacteriuria was slightly lower in the treated than in the untreated group by each of 4 different statistical methods. In a subset of female patients at high risk a significant reduction in the rate of bacteriuria in treated patients was found by 1 method of analysis. These results contrast to previous studies in our hospital in which meatal care, using either nonantiseptic soap and water or an iodophor solution and ointment, was found to predispose to bacteriuria in high risk female patients. The benefit, if any, of meatal care with poly-antibiotic ointment appears to be small.

Travellers' diarrhoea: prevention by chemoprophylaxis

The chemoprophylaxis of travellers' diarrhoea by iodochlorhydroxyquinoline combinations, neomycin and phthalsulphathiazole, furazolidone, bismuth salicylates and streptotriad is reviewed. Streptotriad is regarded as a highly effective prophylactic against travellers' diarrhoea. Some elementary food hygiene precautions are detailed.

Use of steroid/antibiotic prophylaxis in intraocular lens implantation: a double-masked study v placebo

A prospective, randomized, double-masked study was conducted to compare the efficacy of steroid/antibiotic treatment to placebo in reducing postoperative ocular inflammation. Patients undergoing planned extracapsular cataract extraction with intraocular lens implantation were treated with either placebo or a combination product containing dexamethasone, neomycin, and polymyxin B for three days prior to surgery and three weeks following surgery. Five of thirteen (38%) patients treated with placebo developed significant iritis postoperatively, while none of ten (0%) patients treated with the combination product developed excessive inflammation (P = 0.027). Two patients treated with the steroid/antibiotic combination product experienced a broken suture postoperatively followed by iris prolapse, as compared to none in the placebo group (P greater than 0.10). More types and significant numbers of bacteria were isolated from the eyes of the placebo-treatment group after therapy than were found in the steroid/antibiotic-treatment group.

Influence of inhibitors of protein synthesis on restitution of tubular transport capacity after unilateral nephrectomy

One day after unilateral nephrectomy (uNX), excretion of p-aminohippurate (PAH) reaches 80% of control values in rats. A stimulation of tubular transport by repeated administration of xenobiotics shortened the phase of diminished PAH excretion capacity following. The relative extent of compensation (%) after uNX is not affected significantly by inhibitors of protein synthesis. These inhibitors influence the time course of compensation after uNX. Administration of azauracil, fluorouracil and neomycin, respectively, causes a dose dependent reduction of PAH excretion in nephrectomized and sham operated animals. This effect is also provable following pretreatment with cyclopenthiazide, which can stimulate the PAH elimination. A stimulated renal function after uNX can also be suppressed by high doses of inhibitors of protein synthesis. In contrast to this, small doses of these substances produce a stimulation of renal PAH excretion. The extent of this stimulation reached the same degree as after cyclopenthiazide pretreatment found in preliminary experiments. An additional treatment with cyclopenthiazide does not additionally increase PAH excretion. These results indicate that processes of compensatory growth as well as induction of renal tubular transport are caused by increased protein synthesis.

[Improper local corticotherapy in phlebology. Apropos of a case]

Referring to a case history, we remind you that local corticotherapy can have considerable cutaneous side-effects. We describe the case of a patient treated for more than five years for periulcerous eczema by combined triamcinolone and neomycine. This treatment was responsible for cutaneous atrophy and the detachment triggered off a phenomenon which we compare to the corticoidal dermatitis observed following the detachment of prolonged local corticotherapy on the face. The discussion is brought to bear on the method of detachment, which can be either harsh or gentle, using corticoids which are milder, or without fluorine, in the degressive process.

Effects of lactulose and neomycin on urea metabolism in cirrhotic subjects

In our previous studies of cirrhotic subjects lactulose caused a 25% decrease in the urea production rate associated with a decrease in urinary urea excretion and an increase in stool nitrogen. The decrease in the rate of urea production was an indirect measure of reduction in gut ammonia production. The present study was designed to determined if the poorly adsorbed antibiotic neomycin had an additive effect in reducing ammonia production when administered in combination with lactulose. Six stable cirrhotic subjects received isonitrogenous diets during separate lactulose and lactulose + neomycin treatment periods. The addition of neomycin to a lactulose regimen caused a 17% reduction in the urea production rate that was quantitatively accounted for by a 70% reduction in the urea degradation rate. The intestinal urea clearance rate demonstrated a parallel reduction, indicating an inhibition of bacterial ureolysis. There was no evidence that neomycin altered the effects of lactulose since urinary urea excretion did not rise, fecal nitrogen remained high, and stools remained acidic. These results demonstrate that neomycin inhibited bacterial ureolysis when administered with lactulose while lactulose itself was metabolized and its individual effect on nitrogen metabolism persisted. Lactulose and neomycin, when administered together, had an additive effect in reducing gut ammonia production in cirrhotic subjects.

Neomycin concentrations in inner ear tissues and other organs of the guinea pig after chronic drug administration

The kinetics of neomycin entry into tissues, including those of the inner ear, was studied in the guinea pig. The animals received daily subcutaneous injections of 100 mg neomycin/kg body weight and were killed after 1, 3, and 6 days and 1, 2, and 3 weeks. In agreement with previous studies, kidney accumulated the drug rapidly and to a high level (450 micrograms neomycin/g tissue at day 7) while levels in heart, liver, lung, and spleen were lower by more than one order of magnitude. The drug was virtually absent from brain at all times. The salient finding was that neomycin content of cochlear tissues was relatively low. For instance, at 2 weeks, concentrations in organ of Corti (0.7 micrograms/mg protein) and lateral wall tissues (0.4 microgram) were similar to those in heart (0.3 microgram), liver (0.5 microgram), lung (0.8 microgram) and spleen (0.6 microgram) while the concentration in kidney was 6.8 micrograms neomycin/mg protein. The results show that mechanisms of drug entry are different for kidney and cochlea. They also show that the frequently discussed 'accumulation' of aminoglycosides in perilymph is apparently not reflected in tissue levels of the drug.

A biochemical mechanism of the ototoxic interaction between neomycin and ethacrynic acid

The effects of neomycin on tissue levels of ethacrynic acid was studied in vivo and in vitro. In vitro, the addition of neomycin to incubations of synaptosomes and inner ear tissues of guinea pigs raised the concentration of bound ethacrynate approximately two-fold. In vivo, radioactive ethacrynate was determined in the inner ear of mice by radioautography after intravenous injection of the drug (50 mg/kg body weight). Treatment of animals with neomycin (100 mg/kg body weight, intramuscularly) 60 min prior to ethacrynate led to a three-to five-fold higher accumulation of ethacrynate in cochlear structures. It is suggested that neomycin breaks down hemolabyrinthine or tissue permeability barriers and allows increased penetration of the other drug into the inner ear.

Comparative merits of two topical corticosteroid antimicrobial drugs

The anti-inflammatory and antimicrobial activities of two topical creams, one containing halcinonide, neomycin and nystatin (HNN), and the other betamethasone valerate, gentamicin, iodochlorhydroxyquin and tolnaftate (BGI), were compared in a randomized, parallel study of 154 patients (eighty-seven secondarily infected eczematous dermatoses; sixty-seven cutaneous candidiasis). Repeated clinical assessments showed that the two creams produced equivalent therapeutic responses both in patients with infected eczematous lesions and candidiasis. HNN and BGI creams eradicated the bacterial pathogens isolated prior to treatment in 80% and 76%, respectively, of the patients with eczematous dermatoses. The organism most frequently isolated in these patients was S. aureus. Local irritation prompting discontinuance of therapy occurred in just one patient receiving HNN, and two patients receiving BGI.