Evaluation of hypochlorous acid washes in the treatment of chronic venous leg ulcers.

OBJECTIVE: Hypochlorous acid (HOCl) is a highly microbiocidal agent active against bacteria, viruses and fungi. Using quantitative microbiology, preliminary studies showed it achieved an appreciable reduction in the bacterial burden in chronic venous leg ulcers. The study aimed to determine whether it has a role as an additional treatment for chronic venous ulcers that have not healed with conventional treatment. METHOD: On the basis of previous reports we designed a study in which patients acted as their own controls, in that only patients who failed to achieve a 44% reduction in wound size with standard treatment (compression bandaging) received HOCl washes. RESULTS: Of 30 patients admitted to the study, 10 achieved a 44% ulcer reduction after three weeks of standard treatment. In addition to the standard compression treatment, the remaining 20 patients were given HOCl washes over 12 weeks. Of the 20 ulcers, nine (45%) healed and five (25%) reduced in size by over 60%. All patients became free of pain. CONCLUSION: These findings confirm the clinical efficacy of treating venous leg ulcers with hypochlorous washes. Use of HOCl washes as an adjunctive therapy for recalcitrant venous leg ulcers appreciably increases healing and rapidly relieves pain.

Comparison of culture media for detecting methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci.

The detection of methicillin resistance was examined in 51 strains of Staphylococcus aureus and 135 strains of coagulase negative staphylococci using Isosensitest, Diagnostic Sensitivity Test (DST), Mueller-Hinton (MH), Columbia, and Sensitest agars. MH agar with 5% added sodium chloride incubated at 35 degrees C was the most effective in detecting resistance in S aureus, and Columbia agar with 5% added sodium chloride incubated at 35 degrees C was most effective for coagulase negative staphylococci. For clinical purposes, a provisional report of sensitivity for S aureus could be issued after 18 hours; with coagulase negative staphylococci, only resistant strains could be reported at this time. For definitive results cultures must be examined after 40 hours of incubation.

Effects of culture media on detection of methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci by disc diffusion methods.

AIMS: To test 10 culture media for their ability to detect resistance and sensitivity of staphylococci to methicillin by disc diffusion. METHODS: Fifty strains of Staphylococcus aureus and 135 strains of coagulase negative staphylococci were tested using Columbia, Diagnostic Sensitivity Test, Mueller Hinton, Sensitest and Iso-sensitest agars with and without 5% added sodium chloride. Cultures were examined after 18 and 40 hours of incubation. The diameter of the zone and its characteristics were recorded and these media were assessed for their ability to produce clear, readable zones of inhibition. Changes in the variables which determined resistance were investigated. Results were analysed allowing a zone diameter reduction of 8 mm and 10 mm compared with the control in addition to the standard 6 mm. RESULTS: Columbia agar with added sodium chloride supported the growth of all strains, detected the highest number of resistant strains, and was the easiest to read. Resistance was detected after 18 hours in most resistant strains, but some required 40 hours of incubation. There was poor agreement, however, on this medium (63-94%) between disc diffusion and the reference MIC method for sensitive strains. Allowing a greater reduction in zone size resulted in more agreement with sensitive strains but with consequently lowered detection of resistant strains. The other media showed some growth failures and more zones that were difficult to read. More resistance was detected when incubation was prolonged to 40 hours but this was consistently less than on Columbia agar with added salt. CONCLUSIONS: None of the media detected all of the resistant strains. Columbia agar with added salt was the most satisfactory medium in this respect, but it misidentified up to 37% of the sensitive strains as resistant. Methicillin susceptibility testing by disc diffusion testing is unreliable.

A study in vitro of the sensitivity to antibiotics of Bacteroides fragilis.

During a two-year period of observation Bacteroides species were isolated from specimens of pus and vaginal swabs from 115 patients in this hospital. Thirty-five representative strains proved on examination to be Bacteroides fragilis. Minimal inhibitory and minimal bactericidal concentrations of six antibiotics for these strains were determined. All strains were resistant to streptomycin, neomycin, and polymyxin, slightly sensitive to penicillin and ampicillin, and fully sensitive to tetracycline, chloramphenicol, erythromycin, and lincomycin. The minimum bactericidal concentrations of chloramphenicol, erythromycin, and lincomycin were two to four times the minimal inhibitory concentrations. Tetracycline failed to exert any consistent bactericidal effect.The treatment of patients with infections caused by B. fragilis is discussed in the light of the findings in vitro.

The effect of carbon dioxide on the sensitivity of Bacteroides fragilis to certain antibiotics in vitro.

The effect of 10% carbon dioxide on the sensitivity to four antibiotics of 10 strains of Bacteroides fragilis was studied. The minimum inhibitory concentrations of erythromycin and lincomycin hydrochloride for these strains were four to 32 times higher, when grown in hydrogen plus 10% carbon dioxide, than the values obtained when the strains were grown in pure hydrogen. A similar effect was obtained by growing the strains in hydrogen on an acid medium. Except for Haemophilus influenzae and Clostridium tertium the sensitivity to erythromycin and lincomycin hydrochloride of other species of bacteria examined was not affected by the atmosphere in which the tests were carried out. 7-Chlorolincomycin and rifamycin B diethylamide, to which the strains of B. fragilis were uniformly sensitive, were not significantly affected by additional carbon dioxide. The possible mechanisms underlying this phenomenon and its clinical implications are discussed, and a case report describing the successful use of erythromycin in the treatment of a cerebral abscess due to B. fragilis is presented. In a recent study in this laboratory of the sensitivity to antibiotics of B. fragilis the majority of strains were found to be inhibited by 0.15 mug/ml of erythromycin and by 0.55 mug/ml of lincomycin hydrochloride (Ingham, Selkon, Codd, and Hale, 1968). After this work had been completed hydrogen plus 10% carbon dioxide was substituted for pure hydrogen in the anaerobic technique. Strains of B. fragilis isolated on routine culture now appeared to be relatively resistant to erythromycin and lincomycin hydrochloride when their sensitivity was examined by the disc diffusion method. A more detailed investigation of this phenomenon was carried out, the results of which are reported here. The opportunity was also taken to examine the susceptibility of B. fragilis to two new antibiotics, namely, 7-chlorolincomycin and rifamycin B diethylamide.

The API ZYM system in the identification of Gram-negative anaerobes.

The API ZYM reactions of type species of Gram-negative anaerobes representative of those encountered in human infections and of 56 clinical isolates of such organisms, identified by conventional techniques, were investigated. The API ZYM test clearly distinguished between the different genera and species examined and appears to provide a simple, reliable method for the identification of this group of organisms.

The clinical course and management of thoracic empyema.

We report a prospective multi-centre study of the clinical course and hospital management of thoracic empyema in 119 patients (mean age 54.8). The commonest presenting symptom was malaise (75%), 55% were febrile; 31% were previously well with no predisposing condition. Initial treatments were antibiotics alone (5), needle aspirations (46), intercostal tube drainage (61), rib resection (3) and decortication (4). Overall, intercostal drainage was used in 77 patients (16 failed aspirations), surgical rib resection in 24 (1 failed aspirations, 20 failed drainage), and surgical decortication in 28 (6 failed aspirations, 17 failed drainage). Only 4 patients received intrapleural fibrinolytic agents. Aspiration and drainage were likely to fail if the empyema was > 40% of the hemithorax. Median time from treatment start to discharge was: aspirations, 26 days; drainage, 23 days; resection 11 days; decortication, 12 days. Overall 21 patients died (12 with empyema as the major cause); two had been surgically treated. Mortality correlated with age, diabetes, heart failure, and low serum albumin at admission. Infecting organisms, identified in 109 patients (92%) included anaerobes (37), Str. melleri (36), and Str. pneumoniae (28). Six months after discharge, all but six survivors had regained their previous health.

A study of carbon dioxide-dependent strains of Streptococcus milleri.

Forty-four strains of non-haemolytic streptococci, from a variety of sites, that required CO2 for aerobic growth were identified as Streptococcus milleri. Of these strains, 40 (90%) possessed the Lancefield group-F antigen, the remainder being non-groupable with antisera to the group antigens A, C, F and G.

Characteristics of motile curved rods in vaginal secretions.

Motile curved rods seen in vaginal secretions have been isolated on Columbia agar supplemented with 5% human blood and vitamin K. Growth occurred anaerobically and in 5% oxygen but not in more aerobic conditions. There were two distinct groups of these organisms, distinguishable by morphology, biochemical activity and susceptibility to metronidazole. All isolates were sensitive to a wide range of antimicrobial agents, with the exception of nalidixic acid and polymyxin, but one group was resistant to metronidazole. There was little difference between the results of tests of susceptibility to aminoglycosides or to metronidazole performed in anaerobic and microaerophilic conditions. Motile curved rods were isolated from 18 of 80 patients with a clinical diagnosis of non-specific vaginitis, but from only two of 39 without the disease.

Phagocytosis and killing of bacteria in aerobic and anaerobic conditions.

Phagocytosis and intracellular killing of several facultative anaerobes were observed in aerobic and anaerobic conditions. The presence of anaerobes affected these processes. Bacteroides asaccharolyticus and B. fragilis were killed by phagocytes only at bacterial concentrations less than 1 x 10(7) cfu/ml; at higher concentrations of the anaerobes, killing of B. fragilis and concomitant facultative anaerobes was inhibited. This effect appeared to be due to an interaction, in appropriate reducing conditions, between anaerobe and serum, which allowed engulfment of organisms by phagocytes but markedly impaired intracellular killing.

Evaluation of the antimicrobial activity of a new super-oxidized water, Sterilox, for the disinfection of endoscopes.

The antimicrobial activity of a new super-oxidized water, Sterilox, has been tested against Mycobacterium tuberculosis, Mycobacterium avium-intracellulare, Mycobacterium chelonae, Escherichia coli (including type O157), Enterococcus faecalis, Pseudomonas aeruginosa, Bacillus subtilis var niger spores, methicillin-resistant Staphylococcus aureus, Candida albicans, poliovirus type 2 and human immunodeficiency virus HIV-1. Under clean conditions, freshly generated Sterilox was found to be highly active against all these micro-organisms giving a 5 log10 (99.999%) or greater reduction in two minutes or less.

Biochemical mis-identification of Brucella melitensis and subsequent laboratory-acquired infections.

Brucella species are mis-identified in the API 20NE system as Moraxella phenylpyruvica (profile number 1200004). Since some Brucella spp. grow readily in routine blood culture medium and may be isolated from patients without clinically obvious brucellosis, the risk of laboratory-acquired brucellosis exists. We describe two such cases.

Serological responses to brucellosis in HIV-seropositive patients.

Serial sera from 2 patients infected with the human immunodeficiency virus (HIV) type 1 attending a clinic in Nairobi, Kenya, and with blood cultures yielding Brucella melitensis, were tested by enzyme-linked immunosorbent assay for their serological response (Brucella-specific immunoglobulin (Ig) M and IgG) to Brucella infection. Antibody responses were comparable to those of immunocompetent individuals, one patient showing serology typical of acute brucellosis, the other of chronic brucellosis. Sera from 100 other patients, 65 of whom were HIV-positive, attending the same clinic but whose routine microbiological cultures were negative for Brucella, were tested retrospectively for Brucella-specific antibody. Eight had Brucella-specific IgM and IgG, 6 had IgM only and 21 had IgG only, suggesting relatively high levels of exposure to Brucella in the study cohort. There was no association between Brucella antibody status and HIV status. Brucellosis is probably underdiagnosed in Kenya. Brucella serology may be helpful in the diagnosis of patients with non-specific symptoms in East Africa, regardless of HIV status.

Fifteen-year review of the mortality of brain abscess.

Ninety consecutive cases of brain abscess admitted to this center between 1964 and 1978 have been reviewed. The overall mortality has fallen in three consecutive 5-year periods from 42 to 21 to 9.7%. A number of factors seem to be responsible for this. Early surgical intervention was associated with the reduction in mortality between the first and second 5-year periods. Recognition of the significance and extent of cerebral edema, confirmed since computed tomographic (CT) scans have been available, led to a greater use of steroids during the last 5-year period, but the number of patients thus treated was too small to permit an assessment of any effect on mortality. There is no evidence to suggest a change in the natural history of the disease, and surgical management has not altered significantly. Experience with CT scanning in this center in the diagnosis of brain abscess is limited. It is therefore not possible no assess whether any improvement in mortality may have arisen from the early and accurate diagnosis obtainable with this technique. Improvement in culture technique has been of major importance, leading to a better understanding of the bacteriology of brain abscesses. This has allowed a more rational antibiotic program to be instituted, in particular the use of agents active against obligate anaerobes.