The immediate bactericidal effect of lactic acid on meat-borne pathogens

The kinetics of the bactericidal effect of lactic acid decontamination (LAD) on meat-borne pathogens (Salmonella spp., Campylobacter jejuni and Listeria monocytogenes) was studied in an in-vitro model. The bactericidal effect was greatest on organisms in the lactic acid film that replaced the natural fluid on the meat surface during LAD. A stepwise increase in pH from 2.6 to 3.5 and 4.0 progressively reduced the bactericidal effect of decontamination. For treatment with 2% lactic acid for 30-90 s at 21 degrees C, the immediate death of Salmonella spp. decreased from about 0.5-2 log10 cfu at pH 2.6 to an insignificant level at pH 4.0. The immediate death for Camp. jejuni decreased from 2.6 to > 5.3 at pH 2.6 to 0.3-1.0 at pH 4.0. The decrease in bactericidal effect with increasing pH could, however, be countered by an increase in the temperature from 21 degrees C to 37 degrees C. It is suggested that 2% LAD at 37 degrees C for 30-90 s is suitable for elimination of salmonellas on meat but not for L. monocytogenes. Decontamination with 1% lactic acid at pH 3.0 and 21 degrees C for at least 30 s was effective for Camp. jejuni. Mesophilic Enterobacteriaceae were reliable indicators of the LAD-induced bactericidal effect on Salmonella spp. and Camp. jejuni.

Development of resistance to macrolide antibiotics in an AIDS patient treated with clarithromycin for Campylobacter jejuni diarrhea

In an AIDS patient with diarrhea, identical isolates of Campylobacter jejuni susceptible and, later, resistant to macrolide antibiotics were isolated from feces before and after treatment with clarithromycin. Results of rRNA gene restriction analysis and serotyping suggest that development of resistance rather than simultaneous infection with a susceptible and a resistant strain was responsible for this phenomenon. This is the first report of in vivo development of resistance by Campylobacter jejuni in a patient treated with a macrolide for Campylobacter jejuni infection.

Effect of trisodium phosphate on biofilm and planktonic cells of Campylobacter jejuni, Escherichia coli O157: H7, Listeria monocytogenes and Salmonella typhimurium

Trisodium phosphate (TSP) has been approved by the United States Department of Agriculture as a post-chill antimicrobial treatment for raw poultry. This study examines the effectiveness of TSP against planktonic (suspended) and biofilm (attached) cells of Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella typhimurium at room temperature (RT) and 10 degrees C. At either temperature E. coli O157:H7 was the most sensitive to TSP treatments; 10(6) cfu/ml of planktonic or 10(5) cfu/cm2 of biofilm cells were eliminated by a 30 s treatment with 1% TSP. Campylobacter jejuni was slightly less sensitive. Listeria monocytogenes was the most resistant to the effect of TSP, requiring exposure to 8% TSP for 10 min (RT) or 20 min (10 degrees C) to reduce biofilm bacteria by at least one log. Biofilm cells of S. typhimurium and Listeria monocytogenes were more resistant than planktonic cells. Salmonella typhimurium was more sensitive to treatments using TSP at 10 degrees C than at RT. In contrast, L. monocytogenes was more resistant to TSP at 10 degrees C. Trisodium phosphate appears to be an effective treatment for reducing populations of C. jejuni, E. coli O157:H7 and S. typhimurium. This product has the potential to be used for reduction of bacterial counts on other food products besides raw poultry or on food and non-food contact surfaces.

[Campylobacter jejuni and HIV infection]

OBJECTIVE

To evaluate the characteristics of the Campylobacter jejuni infection in HIV positive patients.

DESIGN

We report all cases appeared in our hospital between September 1991 and October 1992 with: HIV infection, chronic diarrhoea and C. jejuni in stool culture. Epidemiologic factors, other opportunist infections, immunologic situation, clinical symptomatology, antibiotic sensitivity and evolution are recorded.

RESULTS

Six patients, 4 men and 2 women, with an average age of 38 years were recorded. They have different risk factors (drug abusers, sexual behaviour and haemophilia). Chronic liver disease and other opportunist infections of the gastrointestinal tract were the most important facts in past history. CD4 count were directly related with the severity of the illness. Quantitative or qualitative disorders of B lymphocytes or immunoglobulins were not found. All of term suffered from chronic diarrhoea with fever in four of them and bacteremia in 2 patients. First generation cephalosporins resistance in one occasion. A good evolution occurred in 3 patients, another had a relapse and bacteremia appeared in 2 patients whose CD4 count were lower of 100/mm3, have AST, ALT changes and other concomitant gastrointestinal infections.

CONCLUSION

C. jejuni infection of the gastrointestinal tract results in chronic diarrhoea with a higher incidence than expected in HIV positive patients. The severity is directly related with CD4 count, and the existence of concomitants infections of the gastrointestinal tract or chronic liver disease. Antibiotic resistance to macrolide is possible, especially in chronic and severe forms.

An in-vitro meat model for the immediate bactericidal effect of lactic acid decontamination on meat surfaces

An in-vitro model of the lactic acid decontamination (LAD) of meat is described. As LAD is a disinfection rather than a preservation process the model is based on the inactivation kinetics of bacteria in a suspension of pork skin. The model takes account of interfering factors present in nature, such as microbial interactions, leaching of organic material from the meat surfaces and buffering activity.

Effect of mutational alteration of Asn-128 in the putative GTP-binding domain of tetracycline resistance determinant Tet(O) from Campylobacter jejuni

The deduced amino acid sequence of Campylobacter jejuni Tet(O), cloned in Escherichia coli, has shown that it contains the five highly conserved sequences of the GTP-binding domain found in other GTPases. Asn-128 belongs to the G4 motif of such a domain and is involved in hydrogen bonding with the guanine ring of the nucleotide. Substitution of Asn-128 by 11 other amino acids resulted in a decrease in tetracycline resistance, indicating that tetracycline resistance conferred by Tet(O) is related to GTP binding. The effect of the mutations on the GTP-binding domain is discussed with the EF-Tu-GDP complex as a model.

Application of Lior biotyping by use of genetically identified Campylobacter strains

We used the scheme of Lior to biotype 140 genetically identified Campylobacter strains. Our results confirmed previous studies and extended Lior biotyping to show that nine C. jejuni subsp. doylei strains (100%) were one biotype and nine C. jejuni subsp. jejuni nalidixic acid-resistant strains (100%) were C. jejuni biotype I or II. All C. jejuni subsp. jejuni hippurate-negative strains studied and 6 of 35 C. lari strains (17%) were grouped with C. coli biotypes. These findings may be useful in epidemiologic investigations.

Azithromycin resistance in Campylobacter jejuni and Campylobacter coli

The MICs of erythromycin, azithromycin and ciprofloxacin were determined for 60 human fecal isolates of Campylobacter. Of these, 30 strains selected on the basis of their resistance to erythromycin by disk diffusion were highly resistant to both erythromycin and azithromycin. Nine of these selected isolates were resistant to ciprofloxacin. The remaining 30 strains were non-selected, consecutive isolates of Campylobacter susceptible to erythromycin by disk diffusion and were shown to be two- to five-fold more susceptible to azithromycin than to erythromycin as determined by MIC testing.

Short-term treatment of traveler's diarrhea with norfloxacin: a double-blind, placebo-controlled study during two seasons

Clinical efficacy of norfloxacin for treatment of traveler's diarrhea in 106 Finnish tourists vacationing in Morocco was evaluated during two different seasons. When the criteria for diagnosis of traveler's diarrhea were fulfilled, norfloxacin (400 mg) or a placebo was given orally, twice daily for 3 days. All symptoms and signs subsided sooner in the norfloxacin group. The clearest difference was observed in the duration of diarrhea: 1.2 days in the norfloxacin group vs. 3.3 days in the placebo group (P < .001). The duration of diarrhea due to particular species was as follows for the two groups: in cases due to Salmonella enterica, 1.1 vs 4.1 days (P < .01); in cases due to Campylobacter jejuni, 1.8 vs. 5.0 days (P < .01); and in cases due to enterotoxigenic Escherichia coli, 1.0 day vs. 3.1 days (P < .01). The rate of full recovery during administration of norfloxacin or a placebo was also greater among the norfloxacin recipients: 84% vs. 47% (P < .001). No significant adverse effects were reported. Norfloxacin proved to be safe and effective in therapy for traveler's diarrhea.

[Compared antibacterial activity of a new fluoroquinolone, sparfloxacin (AT 4140, RP 64206) and four other fluoroquinolones against 332 strains of enteropathogen bacteria]

The in vitro bacteriostatic and bactericidal activity of five fluoroquinolones--sparfloxacin, ciprofloxacin, ofloxacin, lomefloxacin and pefloxacin--was tested against 332 strains of enteric pathogens belonging to the genera Salmonella, Shigella, Escherichia, Yersinia, Vibrio, Campylobacter and Helicobacter. Some of the strains were resistant to one or several antibiotics. Each fluoroquinolone showed identical bacteriostatic activity against susceptible and resistant strains except of those resistant to nalidixic acid. MIC 90% were always below 1 mg/l. The MIC were lowest with ciprofloxacin followed by sparfloxacin and highest with pefloxacin. The five compounds showed different activity against nalidixic acid resistant strains: MIC 90% increased from 0.06 to 4 mg/l for Salmonella, from 0.5 to 4 mg/l for C. jejuni strains, from 0.12 to 16 mg/l for H. pylori strains. All strains remained susceptible to ciprofloxacin and sparfloxacin, but some were intermediate or resistant to the three other compounds. The minimal bactericidal concentrations of the five agents against the nalidixic acid susceptible or resistant strains were one or two times the corresponding MIC.

Cloning and nucleotide sequence of the Campylobacter jejuni gyrA gene and characterization of quinolone resistance mutations

The gyrA gene of Campylobacter jejuni UA580, which encodes the A subunit of DNA gyrase, was cloned and its nucleotide sequence was determined. An open reading frame of 2,589 nucleotides was identified, which could code for a polypeptide of 863 amino acids with a M(r) of 97 kDa. Both the nucleotide sequence and the putative amino acid sequence show ca. 50% identity with those of other gyrA genes from gram-positive and gram-negative bacteria. The locations of the gyrA gene on genome maps of both C. jejuni UA580 and Campylobacter coli UA417 were determined. Six nalidixic acid-resistant isolates of C. jejuni were shown to carry mutations in gyrA. Three clinical isolates had Thr-86-to-Ile substitutions. Three laboratory mutants had substitutions of Thr-86 to Ile, Asp-90 to Ala, and Ala-70 to Thr, respectively. The mutation at Thr-86, which is homologous to Ser-83 in Escherichia coli, was associated with high-level resistance to ciprofloxacin in C. jejuni.

In vitro susceptibility of quinolone-resistant Campylobacter jejuni to new macrolide antibiotics

The MICs of erythromycin and three new macrolide antibiotics were determined for 36 quinolone-susceptible and 106 quinolone-resistant Campylobacter jejuni. The MIC90 values of azithromycin, clarithromycin, roxithromycin and erythromycin were 0.5, 4, 16 and 4 mg/l respectively. No difference was found between macrolide activity against the quinolone-susceptible and the quinolone-resistant strains. Clarithromycin and especially azithromycin might eventually replace erythromycin for the treatment of Campylobacter jejuni infections in view of their pharmacological properties.

Emergence of resistance to erythromycin and fluoroquinolones in thermotolerant Campylobacter strains isolated from feces 1987-1991

During the period 1987 to 1991 a retrospective study was performed to determine the resistance of thermotolerant Campylobacter species isolated from feces to erythromycin and fluoroquinolones. Of the 672 strains studied, 614 (91.3%) were identified as Campylobacter jejuni and 58 (8.7%) as Campylobacter coli. During the study period the rate of resistance of Campylobacter jejuni to erythromycin remained relatively stable (0.9-3.5%), while resistance of Campylobacter coli to erythromycin emerged later (1989) with much higher rates (14.8-33%). Overall, 11.8% and 10.7% of Campylobacter jejuni strains isolated after 1987 were resistant to nalidixic acid and ciprofloxacin respectively, resistance increasing from 2.3% in 1988 to 32% in 1991. In 1991 the first strains of Campylobacter coli with resistance to these fluoroquinolones were detected (rates 29% and 26% respectively). Of the strains resistant to nalidixic acid, only 10.9% were susceptible to ciprofloxacin.

Accuracy of the E test for determining antimicrobial susceptibilities of staphylococci, enterococci, Campylobacter jejuni, and gram-negative bacteria resistant to antimicrobial agents

We compared the results of the E test MIC method with the results of agar dilution susceptibility testing for 18 antimicrobial agents against 324 strains of gram-positive and gram-negative bacteria, including 99 strains of staphylococci, 101 strains of antimicrobial-resistant gram-negative bacteria, 40 strains of enterococci, and 84 isolates of Campylobacter jejuni. Overall agreement of MICs (+/- 1 log2 dilution) was 97.3% for staphylococci, 94.6% for gram-negative bacilli, and 100.0% for enterococci. The MIC results for C. jejuni showed an overall agreement of only 82.9%. This was due primarily to a number of offscale values that limited the number of comparisons with clindamycin, trimethoprim-sulfamethoxazole, and tetracycline. Interpretative criteria for the results of the two test methods, however, were similar. Overall, the E test produced MIC results comparable to those of agar dilution when multiresistant organisms were tested. However, it was necessary to add 2% NaCl to the agar when testing oxacillin against staphylococci for both the E test and agar dilution to obtain results comparable to those of the broth microdilution method.

Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli isolated in Sweden: a 10-year follow-up report

Resistance to erythromycin and doxycycline and more recently to fluoroquinolones has been reported to occur in Campylobacter spp. both in vitro and in patients treated with these antibiotics. The frequency of resistance to 14 antimicrobial agents in Campylobacter jejuni and Campylobacter coli isolated from patients infected in Sweden or abroad is described. For some agents, a comparison of susceptibility in strains of Campylobacter spp. isolated in 1978 with those isolated in 1988 is made. No general increase in in vitro resistance to antibiotics commonly used for the treatment of human gastroenteritis caused by C. jejuni or C. coli has occurred during the last 10 years in Sweden, which might be a consequence of strict antibiotic control. The numbers of strains from 1988 to 1989 resistant to ciprofloxacin and to norfloxacin included in this study (0.7 and 1.4%, respectively) are still fewer than those that were resistant to erythromycin (7.3%) or doxycycline (12.4%). There is, however, since 1989 to 1990 an indication of increasing resistance to these antibiotics.

Characteristics of the internalization and intracellular survival of Campylobacter jejuni in human epithelial cell cultures

The characteristics associated with the internalization and intracellular behavior of Campylobacter jejuni during short-term and long-term cultivation with INT 407 cells were examined. The internalization of C. jejuni by INT 407 cells was inhibited by cytochalasin dansylcadaverine, chemicals that disrupt microfilament formation and inhibit receptor cycling, respectively. Ammonium chloride and methylamine, two chemicals that inhibit endosomal acidification, did not affect C. jejuni internalization. Once internalized, C. jejuni were found exclusively with membrane-bound vacuoles. With regard to intracellular survival, a decline in the number of viable intracellular bacteria, as determined by protection from gentamicin, occurred during the initial phase of infection and when a low level of the antibiotic was maintained in the culture medium. However, the number of intracellular C. jejuni increased markedly after the removal of the antibiotic. In the absence of antibiotic, the infection led to the deterioration of the cell monolayers, indicating that C. jejuni is able to survive within epithelial cells and elicit a cytotoxic effect. The ability of C. jejuni to enter and exert deleterious effects on cells may reflect a pathogenic mechanism associated with enteritis caused by this organism.

[Sensitivity of the pathogen of Campylobacter infection to various antibiotics]

Antibiotic sensitivity of 21 Campylobacter strains isolated from humans, monkeys and birds with diarrhea was assayed and the findings are presented. It was shown that all the isolates were highly sensitive to ofloxacin, pefloxacin, ciprofloxacin, josamycin, pipemidinic acid and amoxyclav (a combination of amoxycillin and clavulanic acid). The predominating majority of the strains were resistant to rifampicin, amoxycillin and phosphomycin. The majority of the cultures were sensitive to erythromycin and roxithromycin while some of the isolates were resistant to them which could be used as an additional biological characteristic of Campylobacter cultures and considered in choosing agents for antibiotic therapy.