Cataglyphis desert ants use distinct behavioral and physiological adaptations to cope with extreme thermal conditions

Some ant species live in hot and arid environments, such as deserts and savannas. Worker polymorphism-variation in worker size and/or morphology within colonies-is adaptive in such ecosystems because it enhances resistance to heat stress and increases the efficiency of resource exploitation. However, species with small, monomorphic workers are also frequently found in these environments. How species with distinct worker size and degrees of polymorphism deal with such stressful environments remains poorly studied. We investigated the behavioral, physiological, and molecular adaptations that may enhance heat and desiccation tolerance in two sympatric species of Cataglyphis desert ants that differ dramatically in worker size and polymorphism: C. viatica is polymorphic, while C. cubica is small and monomorphic. We found that worker size, water content, water loss, and protein regulation play a key role in thermal resistance. (i) Large C. viatica workers better tolerated heat and desiccation stress than did small C. viatica or C. cubica workers. The former had greater water content and lost proportionally less water to evaporation under thermal stress. (ii) Despite their similar size distribution, workers of C. cubica are more heat tolerant than small C. viatica. This higher degree of tolerance likely stemmed from C. cubica workers having greater relative water content. (iii) Under thermal stress, small C. viatica workers metabolized larger quantities of fat and differentially expressed proteins involved in cellular homeostasis. In contrast, C. cubica downregulated the expression of numerous proteins involved in mitochondrial respiration likely reducing ROS accumulation. (iv) Consistent with these results, large C. viatica workers remained active throughout the day; C. cubica workers displayed a bimodal activity pattern, and small C. viatica remained poorly active outside the nest. Our study shows that ecologically similar ant species with different degrees of worker size polymorphism evolved distinct strategies for coping with extreme heat conditions.

Infection control and antibiotic stewardship practices reported by south-eastern Mediterranean hospitals collaborating in the ARMed project

The prevalence of multiply resistant organisms (MROs) reported from south-eastern Mediterranean hospitals highlights the need to identify possible contributory factors to help design control interventions. This was investigated through a structured questionnaire, which examined infection control and antibiotic stewardship practices in hospitals participating or collaborating with the Antibiotic Resistance SurveilLance & Control in the Mediterranean Region (ARMed) project. A total of 45 hospitals (78.9% of invited institutions) responded to the questionnaire; 60% indicated that they faced periods of overcrowding when available bed complement was insufficient to cope with hospital admissions and 62% reported difficulties in isolating patients with MROs due to lack of available beds. Most hospitals relied mainly on washing to achieve hand hygiene, whether by non-medicated or disinfectant soaps. Dependence on solid bars of soap (28.9%) and cloth towels (37.8%) were among the problems identified as well as inconvenient distances of sinks from patient beds (66.6%). Alcohol hand rub was the predominant hand hygiene product in only 7% of hospitals. Programmes for better antibiotic use were mostly limited in scope; 33.3% reported having antibiotic prescribing guidelines and 53.3% of hospitals fed back resistance rates to prescribers. Auditing of antibiotic consumption, whether institution- or unit-based, was carried out in 37.8% of responding hospitals. Multi-faceted approaches aimed at improving isolation of patients with MROs, increasing the emphasis on hand hygiene by encouraging greater use of alcohol hand rubs and introducing effective antibiotic stewardship programmes should be encouraged in south-eastern Mediterranean hospitals.

Correlation between meticillin-resistant Staphylococcus aureus prevalence and infection control initiatives within southern and eastern Mediterranean hospitals

The Mediterranean region has been identified as an area of hyper-endemicity for multi-resistant hospital pathogens. To better understand potential drivers behind this situation, we attempted to correlate already published meticillin-resistant Staphylococcus aureus (MRSA) data from 27 hospitals, participants in the Antibiotic Resistance Surveillance & Control in the Mediterranean Region (ARMed) project, with responses received from the same institutions to questionnaires which dealt with various aspects of infection control and antibiotic stewardship. No difference could be ascertained between high and low prevalence hospitals in terms of scores from replies to structured questions regarding infection control set-up, hand hygiene facilities and antibiotic stewardship practices. However, we did identify differences in terms of bed occupancy and isolation facilities. Hospitals reporting frequent episodes of overcrowding, particularly involving several departments, and which found regular difficulties sourcing isolation beds, had significantly higher MRSA proportions. This suggests that infrastructural deficits related to insufficient bed availability and compounded by inadequate isolation facilities could potentiate MRSA hyper-endemicity in south-eastern Mediterranean hospitals.

Antibiotic resistance in the southeastern Mediterranean - preliminary results from the ARMed project

Sporadic reports from centres in the south and east of the Mediterranean have suggested that the prevalence of antibiotic resistance in this region appears to be considerable, yet pan-regional studies using comparable methodology have been lacking in the past. Susceptibility test results from invasive isolates of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Enterococcus faecium and faecalis routinely recovered from clinical samples of blood and cerebrospinal fluid within participating laboratories situated in Algeria, Cyprus, Egypt, Jordan, Lebanon, Malta, Morocco, Tunisia and Turkey were collected as part of the ARMed project. Preliminary data from the first two years of the project showed the prevalence of penicillin non-susceptibility in S. pneumoniae to range from 0% (Malta) to 36% (Algeria) [median: 29%] whilst methicillin resistance in Staphylococcus aureus varied from 10% in Lebanon to 65% in Jordan [median: 43%]. Significant country specific resistance in E. coli was also seen, with 72% of isolates from Egyptian hospitals reported to be resistant to third generation cephalosporins and 40% non-susceptible to fluoroquinolones in Turkey. Vancomycin non-susceptibility was only reported in 0.9% of E. faecalis isolates from Turkey and in 3.8% of E. faecium isolates from Cyprus. The preliminary results from the ARMed project appear to support previous sporadic reports suggesting high antibiotic resistance in the Mediterranean region. They suggest that this is particularly the case in the eastern Mediterranean region where resistance in S. aureus and E. coli seems to be higher than that reported in the other countries of the Mediterranean.

Antibiotic resistance in the southeastern Mediterranean--preliminary results from the ARMed project

Sporadic reports from centres in the south and east of the Mediterranean have suggested that the prevalence of antibiotic resistance in this region appears to be considerable, yet pan-regional studies using comparable methodology have been lacking in the past. Susceptibility test results from invasive isolates of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Enterococcus faecium and faecalis routinely recovered from clinical samples of blood and cerebrospinal fluid within participating laboratories situated in Algeria, Cyprus, Egypt, Jordan, Lebanon, Malta, Morocco, Tunisia and Turkey were collected as part of the ARMed project. Preliminary data from the first two years of the project showed the prevalence of penicillin non-susceptibility in S. pneumoniae to range from 0% (Malta) to 36% (Algeria) [median: 29%] whilst methicillin resistance in Staphylococcus aureus varied from 10% in Lebanon to 65% in Jordan [median: 43%]. Significant country specific resistance in E. coli was also seen, with 72% of isolates from Egyptian hospitals reported to be resistant to third generation cephalosporins and 40% non-susceptible to fluoroquinolones in Turkey. Vancomycin non-susceptibility was only reported in 0.9% of E. faecalis isolates from Turkey and in 3.8% of E. faecium isolates from Cyprus. The preliminary results from the ARMed project appear to support previous sporadic reports suggesting high antibiotic resistance in the Mediterranean region. They suggest that this is particularly the case in the eastern Mediterranean region where resistance in S. aureus and E. coli seems to be higher than that reported in the other countries of the Mediterranean.

Étude de souches de Neisseria meningitidis sérogroupe B isolées à Casablanca par multilocus sequence typing et électrophorèse en champ pulsé

A previous study showed that B:4:P1.15 was the most frequent phenotype of Neisseria meningitidis isolated in Casablanca (Morocco). To determine if there was an epidemic clone, MLST and PFGE were used to compare 13 B:4:P1.15 strains isolated from September 1999 to December 2000. MLST showed 4 Sequence Types (ST): ST-33 was the most frequent ST (9/13 strains) and 4 strains belonged to 3 newly described STs. Twelve stains belonged to ST-32 complex, and one strain presenting a new ST (ST-2502) did not belong to any known ST complex. The analysis by PFGE showed that the strains were subdivided into 7 clusters, and that there was no epidemic clone. MLST is useful for long-term epidemiological studies on N. meningitidis strains from varied geographical origins. PFGE seemed to be well adapted to the comparison of a small number of strains isolated during a short period within a defined community.

IS6110 restriction fragment length polymorphism of Mycobacterium tuberculosis isolates from an area of Casablanca, Morocco

Using IS6110 RFLP, 61 isolates recovered from new cases of pulmonary tuberculosis (TB) were compared from September to December 1999 in Casablanca, Morocco, a city with a high incidence of TB. The majority of the isolates (92%) harboured 6-14 copies of IS6110. The minimal fraction of patients in groups of recently acquired infection is 13.1%. This preliminary study showed that IS6110 RFLP is a suitable method for finger-printing Mycobacterium tuberculosis in Casablanca. The unexpectedly low level of recent transmission of TB found in this study deserves further studies involving higher numbers of isolates recovered during a longer recruitment period.

Molecular biology of extended-spectrum beta-lactamase-producing Enterobacteriaceae responsible for digestive tract colonization

Twenty-nine extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae strains (14 Klebsiella pneumoniae, 10 Escherichia coli and five Citrobacter diversus) isolated from April to July 1996 from faecal carriers in a surgical intensive care unit at the university hospital of Casablanca (Morocco) were studied. Plasmid content and DNA macrorestriction polymorphism determined by pulsed-field gel electrophoresis (PFGE) were used to compare the strains. Restriction profiles of total genomic DNAs cleaved by XbaI and compared by PFGE revealed nine, four and two clones in K. pneumoniae, E. coli and C. diversus, respectively. Plasmid profile analysis of ESBL-producing strains of K. pneumoniae showed that only seven of 14 isolates had a plasmid; four different plasmid profiles were observed. Three different plasmid profiles were observed in E. coli and two in C. diversus. Plasmids responsible for ESBL production could be transferred by conjugation to E. coli K(12) J53-2 from all E. coli isolates and from four of seven K. pneumoniae. No plasmid transfer could be obtained from C. diversus strains. Restriction enzyme digests of plasmids from transconjugants (four transconjugants of K. pneumoniae and five transconjugants of E. coli) showed different patterns. In the surgical intensive care unit where the survey was conducted, the dissemination of ESBLs was due to a mix of strain spread and strain diversity rather than to plasmid dissemination.

Assessment of the Mycobacteria Growth Indicator Tube for the bacteriological diagnosis of tuberculosis

Fast, accurate diagnosis is necessary for rapid treatment of patients and to prevent the spread of Mycobacterium tuberculosis strains. The rate of recovery, mean time to detection and contamination rates of the Mycobacteria Growth Indicator Tube (MGIT) were compared with Lowenstein-Jensen (LJ) medium for mycobacterial cultures performed on 405 clinical specimens decontaminated by the trisodium phosphate method without benzalkonium chloride. The recovery rate of M. tuberculosis using MGIT was 45/61 (73.8%) compared with the reference LJ. The mean times to detection of M. tuberculosis in smear-positive specimens were 11.9 days with MGIT and 20 days with LJ. For smear-negative samples, the mean times were respectively 18.6 and 31 days, and the contamination rates were respectively 4% and 1.2%. When the trisodium phosphate decontamination method is used, MGIT cannot be used alone for isolation of mycobacteria, but may be used in combination with LJ.

Prevalence of methicillin-resistant Staphylococcus aureus in eight African hospitals and Malta

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious therapeutic problem worldwide, and its frequency in most African countries has not been reported. This study was aimed at determining the prevalence and antibiotic susceptibility patterns of MRSA in eight large hospitals (>500 beds) in Africa and Malta, from 1996 to 1997. Susceptibility to methicillin (oxacillin) and to other drugs was determined by E test (AB Biodisk, Solna, Sweden) on a total of 1440 clinical isolates of S. aureus. Methicillin resistance was detected in 213 (15%) of the 1440 isolates tested. The rate of MRSA was relatively high in Nigeria, Kenya, and Cameroon (21-30%), and below 10% in Tunisia, Malta, and Algeria. All MRSA isolates were sensitive to vancomycin, with MICs <or= 4 mg/L. The isolates were also highly sensitive to ciprofloxacin, except in Kenya, Morocco, and Tunisia, where relative resistance to this drug was noted. Susceptibility to rifampin and fusidic acid seems to be correlated with the clinical use of these compounds. Only 46% of 59 MRSA strains analyzed were susceptible to rifampin, fusidic acid, and ciprofloxacin. The majority (> 60%) of MRSA strains were multiresistant. There is a need to maintain surveillance and control of MRSA infections in Africa.

Serogroups, serotypes, serosubtypes and antimicrobial susceptibility of Neisseria meningitidis isolates in Casablanca, Morocco

Since antigenic characterization and antibiotic susceptibility testing are useful for generating prophylactic recommendations and treatment guidelines, a total of 163 Neisseria meningitidis isolates obtained between January 1992 and September 2000 at the microbiology laboratory of the IbnRochd University Hospital of Casablanca, Morocco, were serogrouped, serotyped, serosubtyped and tested for their susceptibility to five antibiotics. Serogroup B was detected most frequently (75.5%), followed by serogroup A (13.5%). The phenotype B:4:P1.15 represented 74.8% of all serogroup B isolates. Seven (4.3%) isolates demonstrated decreased susceptibility to penicillin G. All isolates tested were susceptible to cefotaxime, chloramphenicol and rifampin. All isolates were inhibited by spiramycin at a concentration of 0.4 mg/l.

Prevalence and characteristics of nim genes encoding 5-nitroimidazole resistance among Bacteroides strains isolated in Morocco

We report here an evaluation of the dissemination of nim genes, encoding 5-nitroimidazoles resistance, among Bacteroides clinical strains isolated in Morocco. This study was done using a PCR method. Among 60 strains studied, nine contain a copy of a nim gene. The sequence determination of these genes showed that they are homologous to three nim genes previously characterized in strains isolated in France: nimB (five genes), nimC (three genes), and nimA (one gene). Although the nimA and nimC genes were previously identified on plasmids pIP417 and pIP419, respectively, we found here that they have a chromosomal location. The MICs of three 5-nitroimidazole antibiotics (metronidazole, ornidazole, and tinidazole) of the nim gene-containing strains were very low (0.5-2 microg/ml), indicating that the nim genes were not efficiently expressed in these clinical isolates.

Two-year surveillance of antibiotic resistance in Streptococcus pneumoniae in four African cities

Worldwide spread of antibiotic resistance in Streptococcus pneumoniae is a major problem. However, data from West and North African countries are scarce. To study the level of resistance and compare the situations in different cities, a prospective study was conducted in Abidjan (Ivory Coast), Casablanca (Morocco), Dakar (Senegal), and Tunis (Tunisia), from 1996 to 1997. The resistances to eight antibiotics of 375 isolates were studied by E test, and the results were interpreted using the breakpoints recommended by the National Committee for Clinical Laboratory Standards. Overall, 30.4% of the isolates were nonsusceptible to penicillin G (25.6% were intermediate and 4.8% were resistant). Amoxicillin (96.3% were susceptible) and parenteral third-generation cephalosporins (92.7%) were highly active. Resistance to chloramphenicol was detected in 8.6% of the isolates. High levels of resistance were noted for erythromycin (28%), tetracycline (38.3%), and cotrimoxazole (36.4%). Resistance to rifampin was rare (2.1%). There were significant differences in resistance rates between individual countries. Multiple resistance was more frequent in penicillin-nonsusceptible isolates than in penicillin-susceptible isolates. Recommendations for treatment could be generated from these results in each participating country.

Serotypes and antimicrobial susceptibility of group B streptococcus isolated from neonates in Casablanca

The serotypes and the levels of antibiotic resistance of 59 Streptococcus agalactiae isolates from neonates in Casablanca, from February 1992 to July 1997, were studied. Most of the isolates (86.4%) were recovered from early-onset disease. The serotype distribution was as follows: serotype III 39%; serotype Ia 32.2%; and serotype V 10.2%. All strains were susceptible to penicillin G, cefotaxime and ampicillin, whereas 1 strain was resistant to erythromycin. No high level of resistance to gentamicin was detected. A vaccine should comprise the most prevalent serotypes and also provide protection against serotype V disease. The antibiotic susceptibility patterns reported here support the recommended treatment and prophylaxis of invasive group B Streptococcal disease.

[Prevalence of bacterial contamination of standard platelet units: prospective study]

BACKGROUND

Platelet concentrates contaminated with bacteria are a main source of transfusion-associated sepsis. Several studies have reported a very wide incidence (0-10%) of contamination. The aim of this study is to assess the prevalence of bacterial contamination of standard platelet units at the regional blood transfusion center in Casablanca.

STUDY DESIGN AND METHODS

During 15.5 months, 3,458 platelet concentrates (PCs) were analysed. The plasma from the bag and the tube was homogenised. One-fifth of the tube contents were inoculated every day for five days in two tubes containing 2.5 mL of Tryptic soy broth. One tube was incubated at room temperature and the other at 37 degrees C for 24 hours. The bacteria were identified by standard procedures.

RESULTS

Twenty-five (0.72%) of 3,458 platelet bags were contaminated. Twenty-two bacteria (88%) were found in the platelet bags stored three days or more, of which 14 (56%) were Staphylococci coagulase negative, two Staphylococcus aureus, one alpha-haemolytic Streptococcus, four bacillus cereus, one Enterobacter cloacae, one Escherichia Coli and two Xanthomonas maltophilia.

CONCLUSION

The incidence reported in this series is higher than that reported by most authors.

[Typing of extended-spectrum beta-lactamase-producing Salmonella typhimurium strains isolated in a pediatric unit]

Extended-spectrum b-lactamases (ESBLs) derive mainly from TEM and SHV b-lactamases. These enzymes confer resistance to all oxyimino cephalosporins and monobactams except cephamycins and carbapems. ESBLs are often encoded by large plasmids that carry resistance determinants to multiple antibiotics and spread among the members of the Enterobacteriaceae. Since the first outbreak of Klebsiella pneumoniae expressing an extended-spectrum beta-lactamase reported in 1984, nosocomial infections due to Enterobacteriaceae species which produce ESBLs have been generally recovered from patients hospitalized in intensive care units. The most frequently isolated ESBL-producing strains belong to the genus Klebsiella, Escherichia, Enterobacter and Proteus; ESBLs are rarely associated with the genus Salmonella. The first Salmonella were detected in France in 1984 (Salmonella typhimurium), in Tunisia in 1988 (Salmonella wien) and in Argentina in 1991 (Salmonella typhimurium). In 1994, 10 isolates of Salmonella typhimurium expressing an extended-spectrum beta-lactamase were isolated for the first time from 10 children hospitalized in a pediatric unit of the hospital Ibn-Rochd, Casablanca. Previous study showed that all isolates belonged the same serotype, and biotype, and showed a resistance to oxyimino beta-lactams, gentamycin, tobramycin and trimethoprim-sulfamethoxazole but remained susceptible to tetracycline, chloramphenicol and quinolones. Oxyimino beta-lactams resistance determinant of all strains of Salmonella typhimurium was transferred by conjugation to Escherichia coli; Resistance to gentamycin and trimethoprim-sulfamethoxazole was also cotransferred. In this study, we characterized the relationship between all isolates by comparing plasmid profiles and patterns of proteins because there appear to be the more effective method for evaluating epidemiologic relationship between Salmonella species, and the protein profiles method has been used for many bacterial species. These two methods have the advantages of speed and simplicity. All isolates presented the same plasmid pattern characterised by three plasmids and the same pattern of proteins composed of 36 bands. We concluded by combining results that this outbreak involved the spread of the same strain of Salmonella typhimurium between the ten children. As this type of resistance is easily transferred by these isolates to other bacterial species, the major risk would be its transfer to Salmonella typhi.

Characterization of extended-spectrum beta-lactamase-producing Salmonella typhimurium by phenotypic and genotypic typing methods

During 1994, 10 isolates of extended-spectrum beta-lactamase-producing Salmonella typhimurium were recovered from children transferred to our hospital from two different centers. Two additional isolates were recovered from two nurses from one of these centers. The aim of this study was to determine if there is any relationship between these isolates. The characterization was done by phenotypic and genotypic methods: biotyping, phage typing, antibiotic susceptibility pattern determination, plasmid analysis, ribotyping (by the four endonucleases EcoRI, SmaI, BglII, and PvuII), pulsed-field gel electrophoresis (PFGE) of genome macrorestriction patterns with XbaI, and randomly amplified polymorphic DNA (RAPD) pattern determination (with the three primers 217 d2, B1, and A3). The same biotype, the same serotype, and an identical antibiotype were found. All isolates were resistant to oxyimino-beta-lactams, gentamicin, tobramycin, and sulfamethoxazole-trimethoprim. All isolates showed an indistinguishable pattern by ribotyping and very similar patterns by PFGE and RAPD. The overall results indicated the spread of a closely related strain of S. typhimurium in children and nurses.

Prospective randomized comparative trial of pefloxacin versus cotrimoxazole in the treatment of typhoid fever in adults

Pefloxacin, which has been shown to have a high in vitro activity against Salmonella spp., was compared to cotrimoxazole in the treatment of typhoid fever in adults. In a prospective, randomized trial, 42 patients with bacteriologically documented typhoid fever received either 400 mg pefloxacin b.i.d. or 160/800 mg cotrimoxazole b.i.d. Duration of treatment was 14 days in both groups. All patients were cured without experiencing a relapse or becoming a salmonella carrier. Apyrexia and resolution of digestive and neurological symptoms were obtained in a significantly shorter time with pefloxacin than with cotrimoxazole. Pefloxacin was well tolerated and more effective than cotrimoxazole in the treatment of typhoid fever.

Highly sensitive biotin-avidin sandwich ELISA for the rapid detection of pneumococcal capsular polysaccharide antigens

The immunological detection of soluble pneumococcal polysaccharide antigens in pathological products is of importance in the direct diagnosis of meningitis or pulmonary infections. We have developed a double antibody sandwich ELISA method using a biotin-avidin system using antibodies constituted with a mixture of IgGs from pooled and/or monospecific antipneumococcal sera provided by the Danish Statens Seruminstitut. The sensitivity of this rapid ELISA method was optimized with purified capsular polysaccharides of the 24 main pneumococcal serotypes. With incubation steps of 30 min at 37 degrees C for the antigens and the conjugates, the detection limit was close to 1 ng/ml for 75% of the purified polysaccharides. A retrospective study of 46 CSF samples established the validity of the assay. This type of modified ELISA system represents a specific, sensitive and rapid procedure for the potential detection of capsular soluble antigens of all pneumococcal serotypes.

[Oral amoxicillin for purulent meningitis in the child: early relief and reduction in symptoms]

The pharmacokinetics of amoxycillin in the CSF following intravenous and oral administration at a 150 mg/kg per day or 250 mg/kg per day dosage in the treatment of purulent meningitis is described. A significant correlation between meningeal inflammation and CSF levels of amoxycillin were observed, including a correlation between the initial neurological state and the outcome of the illness. Despite the early introduction of oral therapy and the reduction in dosage following meningeal and pneumococcal meningitis, no treatment failures could be attributed to this therapeutic regime. Such a treatment schedule, moreover, reduces the risk of superinfection in hospital as well as the cost of treatment and aids the comfort to the patient.

[Significance of the determination of lactic acid in the cerebrospinal fluid for the differential diagnosis of meningitis]

Measurement of cerebrospinal fluid lactic acid by an enzymatic test has been evaluated in 164 patients. The upper limit of normal CSF lactate was 300 mg/l. The CSF lactate level is useful for differential diagnosis between partially treated pyogenic meningitis and tuberculous meningitis. The increase of CSF lactate is not specific for meningitis and must be interpreted taking into account the clinical situation.

[Etiological evaluation of acute diarrhea in children hospitalized in Casablanca]

A prospective study of pediatric diarrhea was conducted in Casablanca. An etiologic agent was found in 67,8% of 87 ill participants. Rotavirus was the most common cause while Campylobacter jejuni, reported as Rotavirus for the first time in Morocco, was isolated in 11% of the patients.