Two flavones from Artemisia giraldii and their antimicrobial activity

Two new flavones, 4',6,7-trihydroxy-3',5'-dimethoxy-flavone (2) and 5',5- dihydroxy-3',4',8-trimethoxyflavone (3) were isolated from Artemisia giraldii and their structures were identified by spectroscopic methods. These two new flavones showed antibiotic activity against Staphylococcus aureus, Sarcina lutea, Escherichia coli, Pseudomonas aeruginosa, Proteus sp. Aspergillus flavus, and Trichoderma viride.

Glycerol and ichthammol: medicinal solution or mythical potion?

Glycerol and ichthammol (G & I) has been used for generations by otologists. However, there is a paucity of information on both its mode of action and its anti-bacterial properties. The aim of this paper was to ascertain firstly, what the most common organisms found in discharging ears were and secondly, what antibacterial activity G & I had against these organisms. All ear swabs from 1992-1994 in our unit were reviewed to ascertain the prevalence of the commonly isolated organisms. Fresh isolates of these organisms were collected and plated onto agar with wells of glycerol, ichthammol and a combination of both as used in clinical practice. The diameters of the zones of inhibition observed after incubation were measured in millimetres. Common isolates were: Pseudomonas aeruginosa, Staphylococcus aureus, Proteus mirabalis, Streptococcus pyogenes in descending order of frequency. Pure glycerol showed no significant zones of inhibition against any of the organisms tested. The average zones of inhibition for G & I and ichthammol alone were for Staphylococcus aureus 15 mm and 18 mm and for Streptococcus pyogenes: 16 mm and 23 mm. Ichthammol alone was significantly more effective than G & I (p < 0.001). There was no significant activity against Proteus mirabalis and Pseudomonas aeruginosa. The therapeutic benefit of G & I is due in part to the inherent anti-bacterial activity of ichthammol against the Gram positive organisms as well as its anti-inflammatory action and the dehydrating effect of the glycerol.

[Sensitivity of bacteria of the genus Proteus to antibiotics]

Antibiotic susceptibility of 481 cultures of the bacteria belonging to the genus Proteus isolated within 1990-1994 from children with enterocolitis was studied. The study included 10 antibiotics. The efficacy of the antibiotic therapy in 388 children with the above disease was estimated. It was shown that the Proteus isolates were most frequently susceptible to kanamycin, gentamicin and carbenicillin. When used clinically in the treatment of children with Proteus enterocolitis, the antibiotics proved to be the most efficient agents.

Effect of salicylate on expression of flagella by Escherichia coli and Proteus, Providencia, and Pseudomonas spp

Osmotic stress, salicylate, and Mar (multiple antibiotic resistance) mutation are known to block the expression of the OmpF porin. Since these conditions have also been shown to inhibit the expression of P and CFA fimbriae in Escherichia coli, we speculated that they might affect the expression of flagella as well. Hyperosmotic conditions have been shown to block the synthesis of flagellin and expression of flagella in E. coli (C. Li, C. J. Louise, W. Shi, and J. Adler, J. Bacteriol. 175:2229-2235, 1993). In the current study, sodium salicylate was found to inhibit the motility of E. coli, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Providencia stuartii in a reversible, concentration-dependent manner. Swarming did not occur at 20 mM sodium salicylate. Salicylate also blocked the synthesis of flagellin in E. coli. Phenotypic Mar mutants of E. coli derived from motile strains were amotile. Flagella were markedly reduced as determined by scanning electron microscopy when P. mirabilis was grown in broth containing 20 mM salicylate. Salicylate had no apparent effect, however, on expression of a 40-kDa porin protein in P. mirabilis. This finding suggests that the noted effect of salicylate on Proteus spp. may be mediated through a mechanism other than porin production or that the Proteus porin may not be analogous to OmpF in E. coli. Salicylate decreased the motility of Pseudomonas cepacia but had no effect on Pseudomonas aeruginosa. The exact mechanism by which salicylate exerts its effect is not known, but it appears to be related to osmoregulation.

In vitro activity of subinhibitory concentrations of quinolones on urea-splitting bacteria: effect on urease activity and on cell surface hydrophobicity

The effect of subinhibitory concentrations of ciprofloxacin, lomefloxacin, norfloxacin, ofloxacin, and sparfloxacin on urease activity and on cell surface hydrophobicity of urea-splitting bacteria was examined. Quinolones at 0.5 MICs demonstrated variable effects on bacterial-urease activity. Norfloxacin inhibited enzyme activity in Proteus vulgaris and Proteus mirabilis, while other quinolones had no effects. In Morganella morganii, sparfloxacin and ciprofloxacin enhanced urease activity, particularly at the initial phase of growth. All quinolones tested showed no marked effect on urease activity by Providencia rettgeri. Quinolones at the same concentrations induced an increase in the cell surface hydrophobicity, which was strain-dependent. There was no correlation between urease inhibition and cell surface hydrophobicity. Inhibition of urease activity by quinolones, in addition to their antibacterial activities, may prevent the progression of urinary tissue damage and stone formation.

[Antibacterial activities of fosfomycin against recent clinical isolates from patients of otitis media and otitis externa]

Clinical isolates from patients with otitis media and/or otitis externa were collected at otorhinology clinics nationwide and sent to us during 1989, 1991 and 1993. Minimum inhibitory concentrations (MICs) of fosfomycin (FOM) and of reference drugs against these strains were determined to investigate year-to-year antibacterial activity of FOM. A comparative analysis of the results revealed trends described below. 1. The MIC90 of FOM against Staphylococcus aureus subsp. aureus increased 4 times by 1993 as compared to those measured for strains isolated in 1984 and 1985, when FOM for otic use was under development. This was thought to be due to the recent increase in the detection frequency of methicillin-resistant S. aureus (MRSA) which is also resistant to FOM. 2. No annual changes were seen for MIC distribution of FOM against Proteus group and Pseudomonas aeruginosa. 3. Since there was no large annual change in the antibacterial activity of FOM against recent clinical isolates obtained from patients with otitis media and/or otitis externa, FOM may be considered as one of the useful drugs even now, in the mid-1990's.

The effect of antiseptic solutions on microorganisms in venous leg ulcers

The effect on the microbial ulcer flora of wet gauze dressings soaked in antiseptic solutions used for desloughing leg ulcers is not known. Quantitative cultures were therefore performed in 45 venous leg ulcers, before application and after 15 minutes' treatment with gauze dressings with four different antiseptic solutions: aluminium acetotartrate (Alsol) 1%, potassium permanganate 0.015%, acetic acid 0.25% and chloramine 0.25%. The percentage of ulcers with each type of microorganism did not differ before and after application of the antiseptic solutions. Staphylococcus aureus was found in 79% of the ulcers, gram-negative rods in 39%, S. epidermidis in 21%, Proteus spp in 21%, Pseudomonas spp in 14% and fungi in none. Potassium permanganate reduced the mean number of bacteria per ulcer from 4.4 x 10(6) to 0.9 x 10(6) (ns), chloramine from 2.7 x 10(6) to 2.2 x 10(6) (ns), Alsol from 1.2 x 10(7) to 3.5 x 10(6) (ns) and acetic acid from 6.3 x 10(6) to 2.6 x 10(5) (p = 0.007). S. aureus was reduced by acetic acid (p = 0.002), gram-negative rods by both chloramine (p = 0.03) and acetic acid (p = 0.03). The number of Pseudomonas, Proteus, S. epidermidis and Streptococcus haemolyticus group G was not reduced significantly (p > 0.05) by any of the solutions.

[Bacteriological study of purulent otitis media in children in CHU in the tropical zone]

BACKGROUND

Haemophilus influenzae and S pneumoniae are the most common causative agents of acute otitis media in Europe and the USA. This work aimed to identify the agents in Senegal and to study their sensitivity to antibiotics.

POPULATION AND METHODS

Two hundred and one patients, aged 0 to 15 years, with persistent middle-ear effusion, were included in this study from 1983 to 1993. Purulent samples aspirated from the external canal were analysed for bacteriology and sensitivity testing.

RESULTS

Eighty two percent of cultures were positive for Staphylococcus aureus (37%), Pseudomonas aeruginosa (25%), Proteus (18%) and Klebsiella (8%). Positive cultures were found mainly in children aged between 1 and 5 years. Amikacin and cefotaxim were the most active antibiotics against the majority of strains. Staphylococcus aureus was always resistant to penicillin.

CONCLUSIONS

Prevalence of Staphylococcus aureus as the causative agent of persistent middle-ear effusion may be explained by late examination. Its resistance to penicillin favors early administration of third generation cephalosporins or pristanimycin.

In vitro activities of antimicrobial agents against Proteus species from clinical specimens

Two hundred clinical isolates of members of the genus Proteus were definitively identified and their antimicrobial susceptibilities to 12 antimicrobials tested, 176 isolates (88%) being identified as Proteus mirabilis, 12 strains (6%) as Proteus vulgaris and 12 strains (6%) as Proteus penneri. Most strains were isolated from pus (62.5%) and urine (34%), but in general there were no significant differences in the rates of isolation of any of the species by age or sex, although it was noted that P. vulgaris was only isolated from patients belonging to the older age group (> 5 years). The Proteus spp. were notably susceptible to nalidixic acid, ceftazidime and the aminoglycosides tested, and resistant to polymyxin B and colistin. The inclination of certain Proteus species to be susceptible or resistant to certain antimicrobials was noted, but strain differences also existed. The results of the study confirm the importance of performing antimicrobials susceptibility testing of each Proteus isolate to avoid potentially misleading therapy. The noted discrepancy in the result of the susceptibility of P. penneri to chloramphenicol as tested by different standard methods merits further investigation.

[Properties of a cephalosporinase produced by Proteus penneri inhibited by clavulanic acid]

P. penneri produces an inducible cephalosporinase, as many Enterobacteriaceae. Nevertheless this betalactamase is susceptible to clavulanic acid which is an exception also encountered for P. vulgaris. The authors studied the enzyme produced by P. penneri 14HBC resistant to cefotaxime (MIC 16 mg/l) isolated in Spain in 1992. This betalactamase of isoelectric point 6.65 hydrolyzes first generation cephalosporins, amoxycillin and poorly ticarcillin as it occurs for all cephalosporinases. However, this enzyme hydrolyzes strongly oxyimino-cephalosporins: cefuroxime, cefotaxime, cefepime, cefpirome as it occurs with extended-spectrum betalactamases. Cephamycins and imipenem are not substrates. Clavulanic acid has a very good affinity for this betalactamase which is inactivated progressively. These properties are similar to those of the enzyme of P. vulgaris Ro104 of isoelectric point 8.3 which, contrarily to other cephalosporinases, belongs to the structural Ambler's class A.

[Statistic studies on bacteria isolated from urinary tract infections (report 6: isolation rate and drug sensitivity from 1988 through 1989)]

We examined the bacteria isolated from urine of patients in our department from 1988 though 1989. A total of 809 strains were isolated from the outpatients. They were 241 strains of gram-positive bacteria (29.8%). E. coli (32.0%) was isolated most frequently, followed by Enterococcus spp. (9.9%), Proteus group (7.4%), S. epidermidis (6.2%), P. aeruginosa (5.1%) and others. A total of 412 strains were isolated from the inpatients. They consisted of 173 strains of gram-positive bacteria (42.0%). Enterococcus spp. (17.0%) was isolated most frequently, followed by P. aeruginosa (12.6%), S. epidermidis (9.7%), E. coli (7.3%), S. aureus (6.6%) and others. Fewer P. aeruginosa, S. marcescens and Proteus group were isolated from the outpatients and fewer S. marcescens, E. coli and K. pneumoniae from inpatients than previously. More S. aureus were isolated abruptly from the inpatients and more E. coli were isolated from the outpatients than previously. E. cloacae, S. epidermidis, S. aureus and Corynebacterium spp. all isolated from inpatients showed lower antimicrobial sensitivity than those isolated from the outpatients.

[Antibacterial activities of cefmenoxime against recent clinical isolates from patients of otitis media and otitis externa]

Bacteria clinically isolated from patients of otitis media and otitis externa were collected from various medical facilities across Japan during years 1988, 1990 and 1992, and minimum inhibitory concentrations (MICs) of cefmenoxime and of reference drugs were determined against these strains. A comparative analyses of the obtained results revealed some trends described below. 1. Methicillin-resistant Staphylococcus aureus (MRSA), multiple drug resistant Coagulase-negative staphylococci (CNS) and multiple drug resistant Proteus spp. showed a year to year trend toward a steady increasing. Relative frequencies of occurrence of MRSA in these years, however, remained comparable to that of early 1980's. 2. A year to year trend toward increasing was also found for resistant or insensitive Streptococcus pneumoniae to penicillins and cephems. 3. Multiple drug-resistant Pseudomonas aeruginosa strains were also detected but they showed no trend toward increasing.

Interpretive accuracy of the disk diffusion method for testing newer orally administered cephalosporins against Morganella morganii

Eight newer orally administered cephems (cefdinir, cefetamet, cefixime, cefpodoxime, cefprozil, ceftibuten, cefuroxime, and loracarbef) were tested against 100 clinical strains of Morganella morganii to determine the extent of serious interpretive very major (false-susceptible) errors when current criteria for the disk diffusion test are applied. Agar dilution MICs and disk diffusion tests were performed as recommended by the National Committee for Clinical Laboratory Standards (Villanova, Pa.) (NCCLS), and the methods were compared by regression analysis using the method of least squares and by error rate bounding. The following results are listed in the order of increasing error rates: cefdinir, loracarbef, and cefprozil, < or = 1% very major error; ceftibuten, 8% minor errors; cefuroxime, 21% minor errors; cefixime, cefpodoxime, and cefetamet, very major errors of 15, 24, and 36%, respectively. M. morganii produces unacceptable rates of test error with cefuroxime, cefixime, cefpodoxime, and cefetamet. The latter two cephalosporins currently have NCCLS table footnote warnings covering the problem observed with this organism. The inclusion of cefuroxime and cefixime in the NCCLS table footnote is strongly recommended.

Alpha-keto acids are novel siderophores in the genera Proteus, Providencia, and Morganella and are produced by amino acid deaminases

Growth promotion and iron transport studies revealed that certain alpha-keto acids generated by amino acid deaminases, by enterobacteria of the Proteus-Providencia-Morganella group (of the tribe Proteeae), show significant siderophore activity. Their iron-binding properties were confirmed by the chrome azurol S assay and UV spectra. These compounds form ligand-to-metal charge transfer bands in the range of 400 to 500 nm. Additional absorption bands of the enolized ligands at 500 to 700 nm are responsible for color formation. Siderophore activity was most pronounced with alpha-keto acids possessing an aromatic or heteroaromatic side chain, like phenylpyruvic acid and indolylpyruvic acid, resulting from deamination of phenylalanine and tryptophan, respectively. In addition, alpha-keto acids possessing longer nonpolar side chains, like alpha-ketoisocaproic acid or alpha-ketoisovaleric acid and even alpha-ketoadipic acid, also showed siderophore activity which was absent or negligible with smaller alpha-keto acids or those possessing polar functional groups, like pyruvic acid, alpha-ketobutyric acid, or alpha-ketoglutaric acid. The fact that deaminase-negative enterobacteria, like Escherichia coli and Salmonella spp., could not utilize alpha-keto acids supports the view that specific iron-carboxylate transport systems have evolved in members of the tribe Proteeae and are designed to recognize ferric complexes of both alpha-hydroxy acids and alpha-keto acids, of which the latter can easily be generated by L-amino acid deaminases in an amino acid-rich medium. Exogenous siderophores, like ferric hydroxamates (ferrichromes) and ferric polycarboxylates (rhizoferrin and citrate), were also utilized by members of the tribe Proteeae.

An eight-year survey of the antimicrobial susceptibility patterns of 85,971 bacteria isolated from patients in a district general hospital and the local community

Antimicrobial susceptibilities were determined for 85,971 bacteria isolated from clinical specimens in the microbiology department of a single district general hospital during the eight-year period between 1984 and 1991. The isolates included 45,786 coliforms, 4483 Proteus spp. and 2644 Pseudomonas spp. from urine and 13,324 Staphylococcus aureus, 7311 beta-haemolytic streptococci, 4741 coliforms, 3643 Pseudomonas spp., 2778 Haemophilus influenzae, 638 Proteus spp. and 623 Streptococcus pneumoniae from other sites (excluding blood). Patterns of susceptibility remained largely unchanged during the study period, except for a decline in the susceptibility of Proteus spp. to trimethoprim between 1984 and 1988 which had reversed itself by 1990 and a reduction in the susceptibilities of Pseudomonas spp. and S. aureus to ciprofloxacin between 1986 and 1991. The susceptibilities of coliforms which had been isolated from sites other than the urinary tract to ampicillin, cefazolin and cefuroxime decreased between 1984 and 1988 but a more variable pattern was noted in subsequent years. Susceptibility of S. aureus to penicillin fell during the first five years of the study but has remained stable since. No change was observed in the susceptibility pattern of H. influenzae. In our experience, gentimicin-resistant Gram-negative bacilli, methicillin-resistant S. aureus and penicillin-resistant S. pneumoniae were rarely isolated.

[Antimicrobial susceptibility patterns of the Proteeae in Japan, 1989]

We discussed the antimicrobial susceptibilities of Proteeae isolated in Japan, 1989. Eight hundred six clinical isolates were collected from 47 hospitals. These were comprised of 431 strains of Proteus mirabilis, 155 Proteus vulgaris, 154 Morganella morganii, 44 Providencia rettgeri and 22 Providencia stuartii. Antibiotics tested in this study were 2 penicillins, 5 cephems, 1 carbapenem and 2 aminoglycosides. The MIC's were determined using the standard method of the Japan Society of Chemotherapy. Susceptibilities of the above strains to these antibiotics are described below; 1. Latamoxef, ceftizoxime and imipenem had excellent activities with no evident differences among the species of Proteeae. 2. Ampicillin and cefazolin were less active against Indol-positive Proteeae. 3. Piperacillin and cefmetazole were also strongly active drugs against P. mirabilis, P. vulgaris and P. stuartii, and cefotiam against P. mirabilis and P. stuartii. 4. Gentamicin and netilmicin showed excellent activities against M. morganii.

[Evaluation of a micromethod for the bactericidal activity of five disinfectants on 108 hospital strains]

The authors studied 5 disinfectants containing aldehyde and quaternary ammonium against 108 hospital strains. The minimal bactericidal activities (MBC) were determined with a microdilution method and the dilution-neutralization method (AFNOR T 72-150). The microdilution method results were validated using the MBCs of four reference strains tested with the dilution-neutralization method (AFNOR T 72-150). 3 disinfectants proved to be valuable. 1 disinfectant was valuable but with a MBC toward all bacteria only a dilution away from the dilution of use. 1 disinfectant was determined as unsatisfactory as 9.5 p. cent of all strains proved resistant toward it. All disinfectants matched AFNOR standards; but those specifications did not match toward hospital strains. Such an evaluation using a simple and reliable method should be of use.

[Microorganisms isolated from chronic suppurative otitis media and their antimicrobial sensitivities]

In this study mycologic and bacteriologic cultures were made in 100 patients who had chronic suppurative otitis media. We observed 58.8% pure, 35.3% mixed growth (more than one bacteria or bacteria and fungus) in the cultures. In pure cultures, we found mostly Proteus sp., S. aureus and Pseudomonas sp. respectively. In 134 bacteriologic cultures most frequently isolated bacteria was S. aureus (36.6%). In Sabouraud agar, we found mostly Aspergillus sp. and Candida sp. (28.6%). In antimicrobial sensitivity test, gram negatives were found to be sensitive mostly to ofloxacin (73.5%), pseudomonas was found to be sensitive mostly to tobramycin (70%). In the staphylococci the antimicrobic which had the highest sensitivity rate was gentamicin (75.5%), but at the same time we observed 24.5% resistance to this antimicrobic agent. Following this respectively, ofloxacin 71.4% sensitivity 4.1% resistance, cefuroxime 69.4% sensitivity 10.2% resistance rate were detected.

Proteus penneri isolated from the pus of a patient with epidural abscess

P. mirabilis and P. vulgaris are the two wellknown species in the genus Proteus. P. myxofaciens and P. penneri are recent additions to the genus. We isolated P. penneri from the pus of a patient with suppurative otitis media and an epidural abscess. The characteristics of the organism, including morphology, staining, physiology and biochemistry, were studied. Clinical microbiological laboratories should suspect P. penneri in the case of as Proteus strain that is negative for indole, salicin and esculin, but otherwise resembles P. vulgaris. Proteus penneri, formerly known as Proteus vulgaris indole-negative or as Proteus vulgaris biogroup 1, was named by Hickman et al in 1932. Little information about human infection by this organism is available. In 1982, Hickman and co-workers studied 20 strain of P. penneri which were isolated from clinical specimens (urine, stool, etc.) in the USA. However, its clinical significance, until recently, was unknown. We isolated a strain of P. penneri from the pus of a patient with suppurative otitis media and an epidural abscess on June 10 and 15, 1989. This paper concerns the problems encountered in identifying this organism and its clinical significance.

[An experimental study of a lactoglobulin preparation against opportunistic bacteria and salmonellae]

A preclinical study of seven batches of lactoglobulin, a new biological preparation against opportunistic bacteria and salmonellae, has been carried out. High antibacterial activity of the preparation with respect to the virulent forms of Salmonella typhimurium, Salmonella enteritidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, Proteus mirabilis has been established. The preparation has been shown to be safe and nontoxic. The 4-year term of its storage at a temperature of 6 degrees +/- 4 degrees C has been substantiated.

Imipenem- and meropenem-resistant mutants of Enterobacter cloacae and Proteus rettgeri lack porins

Carbapenems such as imipenem and meropenem are not rapidly hydrolyzed by commonly occurring beta-lactamases. Nevertheless, it was possible, by mutagenesis and selection, to isolate mutant strains of Enterobacter cloacae and Proteus rettgeri that are highly resistant to meropenem and imipenem. Two alterations were noted in the E. cloacae mutants. First, the mutant strains appeared to be strongly derepressed in the production of beta-lactamases, which reached a very high level when the strains were grown in the presence of imipenem. Second, these mutants were deficient in the production of nonspecific porins, as judged by the pattern of outer membrane proteins as well as by reconstitution assays of permeability. As with most porin-deficient mutants, their cultures were unstable, and their cultivation in the absence of carbapenems rapidly led to an overgrowth of porin-producing revertants. Analysis of the data suggests that the synergism between the lowered outer membrane permeability and the slow but significant hydrolysis of carbapenems by the overproduced enzymes can explain the resistance phenotypes quantitatively, although the possibility of alteration of the target cannot be excluded at present. With P. rettgeri mutants, there was no indication of further derepression of beta-lactamase, but the enzyme hydrolyzed imipenem much more efficiently than the E. cloacae enzyme did. In addition, the major porin was absent in one mutant strain. These results suggest that a major factor for the carbapenem resistance of these enteric bacteria is the porin deficiency, and this conclusion forms a contrast to the situation in Pseudomonas aeruginosa, in which the most prevalent class of imipenem-resistant mutants appears to lack the specific channel protein D2 yet retains the major nonspecific porin F.

[Common pathogens in burn infection and changes in their drug sensitivity]

This paper reports common pathogens in burn infection and changes in their drug sensitivity from 1985 to 1988. Gram negative rods constituted 55.7% of all pathogens, while 40.5% were gram positive cocci. The former group consisted of 173 strains of Pseudomonas aeruginosa (28.5%), 55 Proteus (9.1%), 33 Serratia (5.4%), 23 Klebsiella (3.8%) 19, Acinetobacter (3.1%), 18 Enterobacter (3.0%) and 17 E. coli (2.8%). Among gram-positive cocci, Staphylococcus aureus accounted for 32.8%, Staphylococcus epidermidis accounted for 5.6%, and Streptococcus faecalis accounted for 2.1%. All the gram-negative rods and gram-positive cocci showed more resistance against various antibiotics. Ps. aeruginosa were resistant to 24 commonly used antibiotics. However, ciprofloxacin, ceftaztdime and piperacillin were comparatively effective, the sensitivity rates were 92.9%, 91.5% and 78.3%, respectively. Ps. aeruginosa showed a sensitivity rate of 92.5% and 86.1% to amikacin and polymyxin-B, respectively, from 1980 to 1984, but the rates were lowered to 65.9% and 17.3%, respectively, from 1985 to 1988. Staphylococcus aureus showed a sensitivity rate of 88.9% to ciprofloxacin, 76.1% to ceftazidime, 71.4% to amikacin, 48.5% to piperacillin, 63.1% to cefuroxime. This organism showed a sensitivity rate of 87.3%, 83.9%, 81.7% and 82.8% to amikacin, cefoperozone, leucomycin and lincomycin, respectively, from 1980 to 1984, but the sensitivity rates declined to 71.4%, 56.8%, 60.8% and 43.7%, respectively, from 1985 to 1988.

Hydrogen peroxide as an alternative hatching egg disinfectant

The present study examined the effectiveness of H2O2 at different concentrations to disinfect broiler hatching eggshell surfaces and to maintain hatching potential. Under pure culture conditions, .50% H2O2 yielded over a 6 log kill in 30 s of three potential eggshell bacterial contaminants. Under higher H2O2 demands, such as occurs on eggshell surfaces, H2O2 concentrations of 5% (vol/vol) were required to disinfect the shell surfaces (approximately 5 log reduction). Hatchability of fertile eggs from a 44-wk-old flock was significantly increased by 2% following spraying 5% H2O2 in comparison to untreated controls. Level of contaminated eggs and "early-dead" embryos were significantly reduced in the H2O2-treated eggs. In comparison with formaldehyde fumigation, no significant difference in hatchability due to H2O2 treatment was detected in eggs from a 30- or 56-wk-old flock. Eggshell permeability, as measured by egg moisture loss in an incubator, was not significantly affected by H2O2 (5%) or formaldehyde fumigation when compared with untreated or water-sprayed control eggs. These results demonstrated that H2O2 compared favorably to formaldehyde as a hatching egg disinfectant without adversely affecting hatching potential. Under some conditions, H2O2 actually improved the hatching potential of fertile broiler eggs compared with hatchability of untreated eggs.