Antibiotic resistance patterns in gram-negative and gram-positive bacteria causing septicemia in newborns in León, Nicaragua: correlation with environmental samples.

The aim of this study was to identify the bacteria causing neonatal septicemia in a neonatal intensive care unit (NICU) in León, Nicaragua and its relation with bacteria isolated from the environment at the NICU. Our data showed that 74% (34/46) of the bacteria related to newborns with septicemia were Gram-negative and highly resistant to beta-lactams (>85%) and aminoglycosides (80%), leading to treatment failure in 10 neonates with fatal outcome. Although, the prevalence of Gram-positive bacteria (26%) was lower than Gram-negative bacteria, Staphylococcus epidermidis was related to the death of three newborns. No clonal similarity was found among Enterobacter cloacae , Escherichia coli and Serratia liquefaciens isolated from the neonates with septicemia and the NICU environment. However, in order to improve the outcome for neonates with septicemia, infection control practices and appropriate empirical therapy should be considered to reduce the high prevalence of extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria isolated from neonates with septicemia (80%) and from the NICU environment (34%).

The micro-flora of the small bowel in health and disease.

The micro-flora of the proximal jejunum in healthy volunteers was compared with the micro-flora in patients with gastrointestinal symptoms suggestive of spontaneous bacterial overgrowth in the small intestine. Biopsies were taken distally to the ligament of Treitz with a Watson capsule. The samples were diluted and inoculated on selective and non-selective agar plates that were incubated aerobically and anaerobically. No major differences were found in the small jejunum micro-flora in healthy persons or in a heterogenous group of patients with gastrointestinal disorders. Oropharyngeal micro-organisms dominated the micro-flora in all subjects and colonic micro-organisms were found in low numbers in a few subjects from both groups. Streptococcus intermedius and Haemophilus parahaemolyticus were only found in the micro-flora of healthy subjects while Lactobacillus spp. was more frequently found in the samples from patients. Eight of 20 healthy subjects and five of 18 patients met the criterion of small intestinal overgrowth. Emerging evidence suggests that other factors are involved in the pathogenesis of the irritable bowel syndrome complex. There is a need for better understanding of the complicated interactions between the host and the endogenous micro-flora.

Impact of gemifloxacin on the normal human intestinal microflora.

Gemifloxacin is a new fluoroquinolone that has been shown to possess a broad spectrum of antimicrobial activity against gram-positive and gram-negative microorganisms including methicillin-susceptible and methicillin-resistant staphylococci, Streptococcus pneumoniae, Haemophilus influenzae and most members of the family Enterobacteriaceae. The aim of the present study was to investigate the effect of gemifloxacin on the human intestinal microflora. Gemifloxacin was given in oral doses of 320 mg for 7 days to 10 healthy subjects and 5 subjects received a once-daily dose of matched placebo for 7 days. Faecal samples were collected prior to administration (days -8 and -6), during the administration period (days 2 and 4) and after withdrawal of administration (days 8, 11, 21, 28 and 56). In the aerobic intestinal microflora the numbers of enterobacteria were suppressed during the gemifloxacin administration and the numbers of enterococci and streptococci were also decreased. No other aerobic microorganisms were affected. In the anaerobic microflora the numbers of anaerobic cocci and lactobacilli were suppressed during the gemifloxacin administration while no other changes occurred. The microflora was normalized 49 days after the administration of gemifloxacin had stopped. No selection or overgrowth of resistant bacterial strains or yeasts occurred. The ecological impact of gemifloxacin was shown to be selective and similar to that of ciprofloxacin, levofloxacin and ofloxacin.

Antimicrobial susceptibility of anaerobic bacteria from the intestinal microflora of healthy children and antimicrobial-treated children in Nicaragua.

The objective of this study was to determine the antimicrobial susceptibility of anaerobic bacteria from the intestinal microflora of healthy children who had not been treated with antimicrobial agents since birth or at 1, 3, 6, 12, 18 and 24 months of age, as well as from children of the same ages treated with the most commonly used antimicrobial agents in Nicaragua. A total of 947 Bacteroides and 745 Clostridium strains were isolated from 67 healthy and 94 antimicrobial-treated children. The minimal inhibitory concentrations of ampicillin, cefoxitin, imipenem, clindamycin, metronidazole and chloramphenicol were determined by the agar dilution method. Detection of ss-lactamase was made by the nitrocefin assay. No bacterial strains resistant to imipenem, clindamycin, metronidazole or chloramphenicol were found. The susceptibility of Bacteroides species to ampicillin and cefoxitin isolated from antimicrobial-treated children decreased progressively as the children reached 24 months of age, from 88% to 78% and from 94% to 81%, respectively. All the Bacteroides strains isolated from the healthy children were 100% susceptible to cefoxitin when they were <=12 months and 92% susceptible after this age; the susceptibility of Bacteroides strains to ampicillin in these children was from 91% at 1 month to 86% at 24 months of age. All Clostridium strains were susceptible to ampicillin and cefoxitin. The ss-lactamase production was seen only in Bacteroides species. These data indicate that a rational use of antimicrobial agents is needed to avoid the development of resistance in anaerobic bacteria.

Stool cultures obtained before liver transplantation are useful for choice of perioperative antibiotic prophylaxis.

Bacterial infections, especially cholangitis, are still common complications after liver transplantation (LTx). During recent years, multiresistant enterococci have become a nosocomial problem in transplant units. The present prospective study on 26 patients, including 24 patients with chronic liver disease, demonstrated that enterococci were the predominant micro-organism involved in post-LTx bacterial infections. They were cultured in the feces and in other sites of 10 out of 13 (77%) patients who underwent extensive examinations. Ampicillin-resistant Enterococcus faecium strains were isolated in urine or feces of 2 of the 13 patients prior to LTx. Similarly, resistance to ampicillin and gentamicin, the empirically used antibiotics for patients with fever of unknown origin, was found in E. faecium strains in 3 and 2 patients, respectively. Moreover, multiresistant E. faecium and E. faecalis strains were demonstrated in 46% of the patients in the postoperative period (3 months). However, no vancomycin-resistant enterococci were isolated. The use of antibiotics within 4 months prior to LTx significantly increased the risk of developing ampicillin-resistant bacteria at the time of LTx and of infections with bacteria of enteric origin after LTx (P = 0.03 and 0.01, respectively). We conclude that stool and urine cultures performed prior to LTX may be useful for selecting prophylactic antibiotic regimens.

Ecological effects of short-term ciprofloxacin treatment of travellers' diarrhoea.

Forty-two subjects travelling to Mexico for 11 days were enrolled in a randomized, double-blind, placebo-controlled trial comparing ciprofloxacin 250 mg twice daily for three days or placebo for treatment of travellers' diarrhoea. Seventeen (41%) subjects were randomized to treatment. By the last treatment day, all seven evaluable subjects in the ciprofloxacin group, and three of eight evaluable subjects in the placebo group were cured (P = 0.04). The mean time to cure was 26 h for ciprofloxacin and 60 h for placebo-treated patients (P = 0.03). Faecal specimen were collected pre-travel, after four days in Mexico, 48 h post-travel and four weeks post-travel. Potentially pathogenic Escherichia coli strains carrying diarrhoeagenic virulence genes were detected by DNA hybridization tests, during or after travel, in 41% of treated and 31% of asymptomatic travellers. Travel, irrespective of diarrhoea and type of treatment, had a minor impact on the aerobic and anaerobic microflora. In travellers with ongoing diarrhoea, a suppression of the numbers of anaerobic bacteria was found, but the microflora was otherwise virtually unaffected. Significantly increased frequencies of E. coli resistant to ampicillin, doxycycline, chloramphenicol and co-trimoxazole were found during and after travel in all categories of travellers, though more frequently in subjects who experienced diarrhoea. The susceptibility of Bacteroides spp. remained unchanged. The sensitivity of E. coli to ciprofloxacin was not affected by travel, except in four ciprofloxacin-treated subjects who acquired multiresistant E. coli with ciprofloxacin MICs of > or = 0.125 mg/L post-travel. Bacteroides strains with MICs of > or = 64 mg/L were isolated post-travel from four ciprofloxacin-treated patients, and from one of the other 34 travellers not treated with ciprofloxacin.

Serum antibody response to Bacteroides fragilis in experimental sinusitis.

Maxillary sinusitis was induced in New Zealand white rabbits by local inoculation of 10(6) colony-forming units of Bacteroides fragilis NCTC 9343, and the serum IgG, IgA and IgM antibody responses to cell wall antigens were studied. Prior to inoculation, and one, two, three and four weeks after induction, serum samples were obtained and analysed for antibodies to the lipopolysaccharide and the capsular polysaccharide. Capsular polysaccharide from B. fragilis ATCC 23745 was used as control. The rise in IgG activity against NCTC 9343 capsular polysaccharide and lipopolysaccharide was most marked and sustained throughout the four weeks. The increases in IgA concentration were moderate and sometimes transient, and a more pronounced IgA increase was seen with IFA than with EIA. The IgM peak levels were weak and usually declined within two to three weeks. The development of antibody to the lipopolysaccharide was similar to that of the NCTC 9343 capsular polysaccharide antibodies, though somewhat delayed in time. No significant increase in antibody to the control capsular polysaccharide was seen.