Multiple analysis of a foodborne outbreak caused by infant formula contaminated by an atypicalSalmonella virchow strain

An outbreak of food poisoning involving most autonomous Spanish communities was detected in the first half of 1994. The causative food was infant formula milk contaminated by lactose-fermentingSalmonella virchow. It was not possible to isolate the causative strain from the manufacturer's facilities. During the same period of time, there was a significant increase in lactose-non-fermentingSalmonella virchow strains compared with the same period in previous years. Simultaneously, lactose-non-fermenting strains were recovered from clinical samples from children and from some milk samples that were involved in the outbreak. Therefore, it was speculated that the outbreak might be more extensive than initially thought. The following epidemiological markers were used for typing theSalmonella virchow strains involved in the outbreak: (i) phage typing; (ii) ribotyping, using a set of 20 different endonucleases; and (iii) pulsed-field gel electrophoresis, using three different endonucleases. The most useful markers for this serotype were phage typing and pulsed-field gel electrophoresis, since ribotyping was not able to distinguish all strains tested. The results obtained revealed that the outbreak was caused by at least two strains: one presenting phage type 4-4a and pulsed-field patterns Al or A2 and L + or L–, and another presenting phage type 2 and pulsed-field patterns A1 or A2 and L + or L–. The results indicate that the outbreak was more extensive than initially thought and that the Virchow serotype is very clonal in Spain.     

Phage-typing of S. virchow

Summary A typing scheme forS.virchow using 5 phages is described. Since all strains ofS.virchow proved lysogenic it was necessary to propagate the phages on lysogenic cultures. Strains from Denmark, Nigeria and Sweden fell with one exception in each case, into characteristic and distinct types. The majority of English strains were of yet of another phage type. Various physico-chemical reactions of the phages are recorded. The use of coloured medium proved of much value in the recognition of phages.     

Changes in susceptibility ofSalmonella enteritidis,Salmonella typhimurium,andSalmonella virchow to six antimicrobial agents in a Spanish hospital, 1980–1994

To determine changes in the susceptibility patterns ofSalmonella enteritidis, Salmonella typhimurium, andSalmonella virchow over time, resistance to ampicillin, chloramphenicol, tetracycline, gentamicin, trimethoprim/sulfamethoxazole, and nalidixic acid was studied by the disk diffusion method in 1,024, 191, and 61 clinical isolates of these organisms, respectively. All isolates were recovered from 1980 to 1994 at a hospital in Madrid, Spain.Salmonella enteritidis isolates were less resistant (10.9%) thanSalmonella typhimurium (43.5%) andSalmonella virchow (36.1%; p<0.001). The incidence of resistance ofSalmonella enteritidis to ampicillin increased from 2.7% during the period 1980–1982 to 15.6% during 1992–1994 (p<0.001). The resistance ofSalmonella typhimurium to ampicillin, chloramphenicol, and tetracycline increased from 15.2%, 7.6%, and 21.2% respectively in 1980–1982 to 73.3%, 46.7%, and 73.3% in 1992–1994 (p<0.001). These marked increases in antimicrobial resistance suggest the need for public health interventions, several of which are discussed.     

Enteric Fever and Other Extraintestinal Salmonellosis in University Hospital, Nottingham, UK, Between 1980 and 1997

 The clinical spectrum of extraintestinal salmonellosis comprises enteric fever (typhoid and paratyphoid) and invasive infections due to nontyphoidal salmonellae. This study describes the clinical spectrum, management and outcome of all confirmed cases of extraintestinal salmonellosis in patients admitted to University Hospital, Nottingham, UK, between 1980 and 1997. There were 142 cases (children, 42; adults, 100) of extraintestinal salmonellosis, of which 38 (children, 20; adults, 18) were enteric fever, consisting of 21 cases of typhoid, 12 of paratyphoid A and five of paratyphoid B. All patients with typhoid and paratyphoid A fever were from Indian or Pakistani families and, except for two adults, all were considered to be previously fit. The outcome in patients with enteric fever was excellent, and there were no complications. Of the 104 patients (children, 22; adults, 82) with nontyphoidal salmonellosis, 69 were bacteraemic secondary to gastroenteritis, 10 were bacteraemic without an obvious focus of infection and 25 had focal infections. The three major sites of focal infections were meningitis in five infants, osteomyelitis in two children and three adults, and arterial infections in ten adults. The three most frequently isolated organisms were Salmonella enteritidis (40%), Salmonella typhimurium (25%) and Salmonella virchow (14%). Sixty-seven percent of these patients had underlying disease(s)/risk factors. In contrast to the outcome of enteric fever, there were 19 deaths (children, 2; adults, 17) in patients with nontyphoidal salmonellosis. Sixteen of the 17 adults who died were over the age of 60 years. Eight (25%) of 32 males over the age of 60 years with nontyphoidal Salmonella bacteraemia had arterial infections. In some patients, the diagnosis of Salmonella arterial infection is likely to be delayed or missed altogether if blood cultures are not obtained. Mortality in patients over the age of 60 years with nontyphoidal Salmonella infections was 28%.     

An alteration in outer membrane permeability associated with a division lesion in a strain of Salmonella typhimurium

Salmonella typhimurium strain 4a is a temperature sensitive mutant with defects in both septation and separation. The separation lesion was reversed by phenethylalcohol but this agent failed to allow septation or growth at restrictive temperature. Organisms of strain 4a grown at 42 °C were, unlike the parental strain, resistant to lysis by lysozyme plus EDTA and lipopolysaccharide was poorly extracted by EDTA from cultures of strain 4a grown at 42 °C. Such cultures may, therefore, be resistant to lysis with lysozyme plus EDTA not because the murein is altered but because the EDTA fails to permeabilize the outer membrane to lysozyme. In confirmation of this, murein isolated from strain 4a after growth at 42 °C showed the same sensitivity to lysozyme as murein from the parental strain. In spite of the altered envelope properties of strain 4a after growth at 42 °C, no major changes in protein or phospholipid composition have so far been demonstrated.     

Analysis of isolates recovered from multiple sites of the nasopharynx of children colonized by nontypeableHaemophilus influenzae

To determine whether the nasopharynx of children is colonized by a single or multiple strains of nontypeableHaemophilus influenzae, cultures were obtained from six nasopharyngeal sites in five children. For each child, all isolates yielded identical polymerase chain reaction fingerprints. The results indicate that these children were colonized in the nasopharynx with a single strain of nontypeableHaemophilus influenzae at one time.     

Serological grouping and thermal death points of S. virchow bacteriophages

Conclusions S. virchow phages of titre as low as 10⁵/ml were able to produce antibodies of titre of 4,000. Antigenicity of the phages was not affected by heating at 56 for 40 min. or by treatment with 0.4% formalin.Antiphage sera also contained bacterial antibodies. The phages ofS. virchow were classified into two group A phages and six group B phages.Most of the group A 1 phages died at 90 and group A 2 phages at 75 and 80. Group B phages died at temperatures between 56 and 80. Thirty four strains ofS. virchow yielded phages belonging to one serological group, six strains belonging to two different groups and eight strains belonging to three different groups.     

Effect of probiotic strain Lactobacillus acidophilus (LBKV-3) on fecal residual lactase activity in undernourished children below 10 years

Clinically proven Lactobacillus acidophilus strain LBKV-3 intended as probiotic for humans was used to test its effect on fecal residual lactase activity in undernourished children below 10 years of age. The children were selected from malnutrition-declared area of Maharashtra (India). One of the major causes of malnutrition is lactose intolerance which leads to diarrhea. The basic consideration in selecting the probiotic strain of L. acidophilus (LBKV-3) in this investigation was the fact that the organism is isolated from human vaginal surface swab and it was found extensively studied for probiotic characteristic. LBKB₃ is tested by several workers as probiotic for hypocholesterolemic activity, implantation ability, therapeutic effects on gastrointestinal (GI) and related ailments. The results of present investigation have shown that the fecal residual lactase activity significantly increased than its initial value (which was almost zero). It appeared that the fecal residual β-galactosidase activity is an indication of positive implementation abilities of the cultures under investigation. These trends were compared with the control and blank group of children receiving Dahi and buffalo milk (BM). It was observed that both these products failed to exert any significant impact on increase in residual lactase activity.     

Evaluation of a New Chromogenic Medium for the Isolation and Presumptive Identification of Salmonella Species from Stool Specimens

The performance of BBL CHROMagar Salmonella (Becton Dickinson, France), a new selective chromogenic medium for the isolation and presumptive identification of Salmonella spp., was evaluated. On this medium, which is a modification of CHROMagar Salmonella (CHROMagar Microbiology, France) with enhanced selectivity, the colonies of Salmonella are stained in mauve (rose-violet), while those of other organisms appear in blue-green or are not stained by any of the chromogens of the medium. The medium was evaluated with a total of 176 strains of Salmonella and other organisms, consisting of 18 reference strains and 158 clinical isolates. All Salmonella strains except subspecies IIIa and IIIb strains and Salmonella Gallinarum yielded typical mauve colonies. During the evaluation with 107 known positive and 332 unknown stool specimens in a clinical laboratory, a total of 115 and 105 Salmonella isolates were obtained on BBL CHROMagar Salmonella and Hektoen enteric agar, respectively. From the known positive stool specimens, 92 true positive cultures were obtained on BBL CHROMagar Salmonella and 89 on Hektoen enteric agar, yielding sensitivities of 86 and 83%, respectively. From the unknown stool specimens, a total of 27 Salmonella isolates were obtained, with 23 isolated from BBL CHROMagar Salmonella and 16 from Hektoen enteric agar by direct plating (sensitivity 85 and 59%, specificity 99 and 97%, respectively). Seroagglutination tests could be performed directly from BBL CHROMagar Salmonella. Compared to conventional isolation media, the time needed for confirmatory biochemical and serological tests was shortened by about 1 day when BBL CHROMagar Salmonella was used. On the basis of these results, the medium can be recommended for the primary isolation and presumptive identification of Salmonella spp. from clinical stool specimens. Electronic Publication     

Bactericidal activity of culture fluid components of <Emphasis Type="Italic">Lactobacillus fermentum</Emphasis> strain 90 TS-4 (21) clone 3, and their capacity to modulate adhesion of <Emphasis Type="Italic">Candida Albicans</Emphasis> yeast-like fungi to vaginal epithelial cells

Antagonistic activities of L. fermentum strain 90 TS-4 (21), L. casei ATCC 27216, and L. acidophilus ATCC 4356 and bactericidal activity of lactobacillus culture fluid towards E. coli strain K12, S. aureus, and S. epidermidis test cultures were studied. The bactericidal effect of L. fermentum strain 90 TS-4 (21) clone 3 culture fluid preparation (pH 6.0) on the test cultures was dose-dependent. Adhesion of C. albicans yeast-like fungi to vaginal epitheliocytes was more pronounced for strains isolated from women with asymptomatic infection than for strains isolated from women with manifest forms. L. fermentum strain 90 TS-4 (21) clone 3 culture fluid preparation modulated adhesion of yeast-like fungi only if the fungal strain was initially highly adherent. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 3, pp. 330–334, March, 2007     

Investigation of an Outbreak of Wound Infections due to Alcaligenes xylosoxidans Transmitted by Chlorhexidine in a Burns Unit

 Alcaligenes xylosoxidans, an environmental gram-negative bacillus, was isolated within a 1-month period from six patients in a pediatric burns unit. Twelve isolates were studied, one from each of the six patients (five from wound cultures and one from a blood culture) and one from each of six contaminated atomizers containing chlorhexidine diluted to 600 mg/l. The biochemical and susceptibility patterns of all the isolates were similar, and their DNA enzyme restriction patterns were identical. The epidemic strain of Alcaligenes xylosoxidans was probably introduced into the atomizers during handling of the diluted solution, which failed to eliminate it.     

Biochemical characterization of new strains of<Emphasis Type="Italic"> Trypanosoma cruzi</Emphasis> and<Emphasis Type="Italic"> T. rangeli</Emphasis> isolates from Peru and Mexico

Seven trypanosome stocks isolated have been characterized by lectin agglutination, isoenzyme analysis, and the end products excreted. The stocks were isolated from different geographic areas—one from Mexico (TM5), and six from Peru, four of these isolated from different species of triatoma (TP504, TP702, TP704 and TP706), the other two isolated from the salivary glands of Rhodnius ecuadorensis (TRa605 and TRa606). Additionally, one strain of Trypanosoma cruzi isolated from a human case (strain TC-Maracay) and one strain of T. rangeli (TRa, Cajamarca-Peru strain), characterized and maintained in our laboratory, were used as reference strains. According to statistical study, the stocks were grouped into three clusters: (1) cluster I included the reference strain of T. cruzi (TC-Maracay); (2) cluster II was subdivided into two groups—subcluster IIA for the Mexican isolate (TM5) and subcluster IIB for the Peruvian ones, isolated from the salivary glands of Rhodnius ecuadorensis (TRa 605 and TRa 606) and the reference strain T. rangeli (TRa); these two new isolates were classified as T. rangeli; and (3) cluster III for the rest of the Peruvian isolates, which should be considered at least as a different strain from the T. cruzi strain Maracay. We show that the identification of T. cruzi and T. rangeli in mixed infections is readily achieved by biochemical methods. These findings identified three clusters of Mexican and Peruvian stocks that correlate with geographic origin, although assignment to a T. cruzi linage was not possible.     

Outbreak of long-term intravascular catheter-related bacteremia due to Achromobacter xylosoxidans subspecies xylosoxidans in a hemodialysis unit

Achromobacter xylosoxidans is a rare cause of bacteremia. Over a 2-week period, A. xylosoxidans subsp. xylosoxidans was isolated from blood cultures of four hemodialysis patients with long-term intravascular catheters. A culture from one atomizer that contained diluted 2.5% chlorhexidine, which had been used to disinfect the skin, yielded A. xylosoxidans subsp. xylosoxidans. No further cases were diagnosed once the use of this atomizer was discontinued. Five outbreak-related strains from the four patients and the atomizer were tested by pulsed-field gel electrophoresis (PFGE) under XbaI restriction. The isolates from the first three patients and the atomizer had identical PFGE patterns, confirming the atomizer as the source of the outbreak. The strain isolated from the fourth patient had six more bands than the outbreak strain and was considered possibly related to the outbreak strain. All patients were treated with intravenous levofloxacin. The catheter was removed in only one patient. The three patients in whom the catheter was left in place were also treated with antibiotic lock therapy with levofloxacin. All four patients were cured. This is believed to be the first reported outbreak of central venous catheter-related bacteremia due to A. xylosoxidans and the second reported outbreak with this organism associated with chlorhexidine atomizers. The use of diluted chlorhexidine via atomizers can be dangerous for the care of venous catheters and should be called into question. Patients with long-term intravascular catheter-related bacteremia due to this organism can be treated successfully with systemic antimicrobial therapy in addition to antibiotic lock therapy without catheter removal.     

Recovery of Salmonella group B from blood and Salmonella group C2 from feces and serological evidence of dual infection in one patient.

A patient with a dual Salmonella infection is described. Salmonella group B was recovered from three blood culture sets but was not detected in seven stool cultures. Salmonella group C2 was isolated from three of seven stool cultures but was not recovered from blood cultures. Specific, non-cross-reactive antibodies to Salmonella groups B and C2 were detected in the sera of the patient by passive hemagglutination assays.     

Mitogenic activity of cell wall components from smooth and rough strains of Brucella abortus.

On the basis of [3H]thymidine incorporation by normal mouse spleen cell cultures, cell wall preparations from a smooth (45/0) strain and a rough (45/20) strain of Brucella abortus were strongly mitogenic. On the other hand, none of several subcomponents extracted from the cell wall preparations, including aqueous and phenolic lipopolysaccharides, was active. These results contrast with the marked mitogenic activity of lipopolysaccharides isolated from other gram-negative bacteria such as Salmonella typhimurium.     

Investigation of an Outbreak due to Alcaligenes xylosoxydans Subspecies xylosoxydans by Random Amplified Polymorphic DNA Analysis

In 1999, over a 3-week period, Alcaligenes xylosoxydans subsp. xylosoxydans was isolated from five blood cultures and one cerebrospinal fluid specimen from five children hospitalized in a pediatric hematology ward as well as from two respiratory therapy devices of two children hospitalized in an intensive care unit. The infection control unit of the hospital conducted an epidemiological investigation and identified a detergent-disinfectant solution as the source of contamination. Conventional biochemical tests, antimicrobial susceptibility tests and random amplified polymorphic DNA (RAPD) fingerprinting were used to compare clinical and environmental isolates. RAPD analysis proved to be more discriminant than biotyping or antibiotyping in this context and identified the common source of the outbreak. Electronic Publication     

Serotype distribution and antimicrobial resistance of Salmonella enterica from patients with gastroenteritis in Crete, Greece

The aim of the present study was to determine the serotype distribution and the evolution of antimicrobial resistance among Salmonella enterica strains isolated from patients with diarrhea in Crete, Greece, during a 5-year period (2000–2004). Among the 401 S. enterica isolates recovered, serotype Enteritidis was the most prevalent (66.6%), followed by serotype Typhimurium (14.2%). The rates of resistance to ampicillin, amoxicillin-clavulanic acid, gentamicin, chloramphenicol, tetracycline, nalidixic acid and trimethoprim-sulfamethoxazole were 8.5, 7, 0.7, 5.4, 14.2, 2.7 and 2.7%, respectively. A marked decrease in resistance was observed during the study period. Resistance and multidrug resistance was most common in serotype Typhimurium. The extended-spectrum beta-lactamase production observed in one strain of S. enterica serotype Virchow and the reduced ciprofloxacin susceptibility detected in 2.7% of the isolates studied are causes of concern.     

Maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2)

The maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2) was investigated. The presence of the plasmid coding for a neomycin phosphotransferase was detected by plating samples from the continuous cultures on nonselective and selective agar medium containing neomycin. The plasmid was lost from the host strain under all conditions tested. However, the kinetics of the plasmid segregation from the chemostat populations were dependent on the growth-limiting substrate of the medium, the dilution rate of the continuous culture and the cultivation temperature. Size differences between the original plasmid and plasmid DNA isolated from neomycin-resistant clones after long-term chemostat cultivation were not observed. In neomycin-sensitive clones no extrachromosomal DNA was found.     

Variation of vlhA gene in Mycoplasma synoviae clones isolated from chickens

Mycoplasma synoviae synthesizes haemagglutinin VlhA, which cleaves into the N-terminal part, a lipoprotein MSPB, and a C-terminal part MSPA. Previous studies have shown that the 3′-end of the expressed vlhA gene can recombine with vlhA pseudogenes in a process called gene conversion, but there have been no data about diversification of the expressed vlhA gene in M. synoviae populations replicating in chickens. Following intratracheal inoculation with the M. synoviae strain ULB 02/T6, which showed only minor vlhA gene variation prior to inoculation, we investigated temporal changes in MSPB epitopes defined by monoclonal antibodies (mAbs) 3B4 and 50, as well as diversification of the vlhA gene sequence in M. synoviae populations recovered from chicken tracheas. In cultures isolated 8 and 18 days post inoculation (p.i.), most colonies showed variation of MSPB epitopes for mAbs 3B4 and 50. They also changed 3′-end vlhA gene sequences. Further diversity of the vlhA gene occurred in cultures isolated 8 weeks and 5 months p.i. The vlhA gene sequences from isolated cultures shared only 65 to 80% sequence identity with vlhA gene of the inoculated ULB 02/T6 culture. Notably, in most of those cultures their vlhA gene sequences contained stop codons potentially causing premature terminations of translation. Interestingly, in one culture isolated 8 weeks p.i. (clone T6-8W/IT2A) the 3′-vlhA gene sequence was identical in the last 1140 bases to that of the first vlhA pseudogene positioned the most far (upstream) of the expressed vlhA gene. This is the first demonstration of temporal diversity of the vlhA gene in M. synoviae populations isolated from chicken tracheas.     

SHV-12-like extended-spectrum-beta-lactamase-producing strains of Salmonella enterica serotypes Babelsberg and Enteritidis isolated in France among infants adopted from Mali

From December 2002 to June 2003, 14 cultures of Salmonella enterica serotype Babelsberg and 6 cultures of serotype Enteritidis, isolated in France from internationally adopted children, were identified at the French National Reference Center for Salmonella. All serotype Babelsberg isolates were related, as determined by pulsed-field gel electrophoresis, and all serotype Enteritidis strains displayed the same phage type. All serotype Enteritidis and seven serotype Babelsberg isolates produced an SHV-12-like extended-spectrum beta-lactamase as determined by sequencing of PCR products and by isoelectrofocusing. Some serotype Enteritidis isolates exhibited additional antimicrobial resistance (aminoglycosides, tetracycline, chloramphenicol, sulfonamides, and trimethoprim). Our investigation indicated that these Salmonella isolates were certainly acquired in the same orphanage in Bamako, Mali, before the children were adopted by French families. An inappropriate use of ceftriaxone was probably the cause of the emergence of such strains. There is an urgent need to determine the origin of the contamination and to introduce adequate antibiotic protocols into this orphanage to prevent further transmission and dissemination. Screening for infections and follow-up, adapted to the origin of the internationally adopted children, should be recommended.