Demonstration of Borrelia burgdorferi sensu stricto infection in ticks from the northeast of Mexico.

Borrelia burgdorferisensu lato infection has been confirmed in clinical cases in the northeast of Mexico; however, the bacterium has not been identified as infecting the tick vector Ixodes, Amblyomma and Dermacentor ticks were collected from mammals and plants in northeastern Mexico and examined for Borrelia. Eighteen of 214 ticks were PCR-positive for the fla and 16S rRNA genes and 15 for the ospA gene. Southern blotting with a fla probe and sequencing of ospA genes confirmed infection with B. burgdorferi sensu stricto. These findings, together with reports of indigenous cases, fulfil the criteria that allow northeastern Mexico to be considered as a zone endemic for Lyme disease.

Antibacterial effects of commercial essential oils over locally prevalent pathogenic strains in Mexico.

Locally prevalent pathogenic bacteria 189 Gram (-) and 135 Gram (+) strains, all isolated from pediatric patients severely infected, were tested in vitro against 11 essential oils from commercial origin. All the strains showed resistance to selected antibiotics. Cinnamomum verum, Origanum vulgare and Thymus vulgaris exhibited the highest and broadest antibacterial activity. Emphasis is made in the potential implications of these resources, uncommon at the clinical setting of the study, employed against non-commercial, locally pathogenic strains, being a step to submit in the ensuing period essential oils from plants used in Mexican traditional medicine.

Surveillance of methicillin-resistant Staphylococcus aureus in a pediatric hospital in Mexico City during a 7-year period (1997 to 2003): clonal evolution and impact of infection control.

Between 1997 and 2000 a single multidrug-susceptible methicillin-resistant Staphylococcus aureus clone, M (sequence type 30 [ST30]-staphylococcal cassette chromosome mec [SCCmec] type IV), was present in a pediatric hospital in Mexico City, Mexico. In 2001 the international multidrug-resistant New York-Japan clone (ST5-SCCmec type II) was introduced into the hospital, completely replacing clone M by 2002.

Meeting the challenge: prevention of pneumococcal disease with conjugate vaccines.

Streptococcus pneumoniae is one of the leading causes of both invasive and noninvasive diseases in the pediatric population and continues to represent a significant public health burden worldwide. The increasing incidence of antibioticresistant strains of the pathogen has complicated treatment and management of the various pneumococcal disease manifestations. Thus, the best management strategy may be the prevention of pneumococcal diseases through vaccination. Although several pneumococcal conjugate vaccines have been clinically studied in infants and children, only a 7-valent conjugate vaccine (PNCRM7; Prevnar/Prevenar) is currently approved for the prevention of invasive disease. Vaccination with PNCRM7 is safe and effective in infants and young children. Routine vaccination with the conjugate vaccine could improve outcomes by safeguarding against the development of antibiotic-resistant strains of S. pneumoniae, thus simplifying the management of pneumococcal disease. Additionally, the overall costs associated with the treatment of pneumococcal diseases could be substantially reduced, particularly in developing countries. The time has come for fully applying this new advancement against S. pneumoniae, to benefit the children of the world. The English version of this paper is available at: http://www.insp.mx/salud/index.html

[Congenital rubella syndrome in infants treated at a pediatrics hospital]. / Síndrome de rubéola congénita en lactantes atendidos en un hospital pediátrico.

UNLABELLED: Congenital rubella syndrome (CRS) has been considered an uncommon problem in Mexico. OBJECTIVE: To analyze and describe clinical features of CRS cases in infants from a pediatric hospital in Mexico City during an 8 year period. DESIGN: retrospective study. Patients younger than 18 months of age with a positive serologic test for IgG and IgM rubella antibodies were included. Antibodies were measured by an immunoenzymatic microparticles assay. RESULTS: Fifty-six cases were identified, 42 complete clinical records were available for review. Of these, 23 (54.7%) were female and 19 (45.3%) male. Median for age was five months. A total of 9/42 mothers (21%) had history of rash during pregnancy. IgM antibodies were detected in 15 infants and IgG in 27. Major manifestations were ocular (74%), neurologic (66%), and congenital heart disease (67%). Congenital cataracts were detected in 69%, in 52% hepatomegaly, in 43% jaundice, in 40% anemia, in 48% thrombocytopenia, and hearing loss 19%. CONCLUSION: Five confirmed cases with CRS per year in one hospital indicate a high frequency. Only a small percentage of women had a history of rash during pregnancy. CRS must be investigated in infants with ocular, neurologic, and congenital heart diseases.

[Prevalence of Moraxella catarrhalis colonization in asymptomatic carriers under 6 years of age]. / Prevalencia de colonización por Moraxella catarrhalis en portadores asintomáticos menores de seis años.

OBJECTIVE: To determine the prevalence of upper respiratory tract colonization by Moraxella catarrhalis in children under six years of age. MATERIAL AND METHODS: A survey was conducted between January and December 1998 in Mexico City, among children aged 2 months to 5 years, selected through cluster sampling. Pharyngeal samples were taken for M. catarrhalis identification. The minimal inhibitory concentration to different antibiotics was obtained and beta-lactamases were determined by the iodometric test. Statistical analysis consisted of frequency distributions, odds ratios, 95% confidence intervals, and Mantel-Haenszel chi 2. Statistical significance was set at p < 0.05. RESULTS: After excluding 37 children, the study population was 604 children from Mexico City; M. catarrhalis was present in 130 pharyngeal specimens (22.9%). Most of the strains were positive for beta-lactamase production (75.4%). Eighty percent of the strains was resistant to penicillin and 70% to ampicillin and amoxicillin. None were resistant to cefotaxime, imipenem, meropenem and erythromycin. CONCLUSIONS: Prevalence of M. catarrhalis upper respiratory tract colonization is similar to that of other respiratory pathogens. These findings warrant future research on the role of M. catarrhalis as an etiologic agent in acute and chronic respiratory infections in Mexico.

Live varicella vaccine in both immunocompromised and healthy children.

BACKGROUND: There is no information on the use of live varicella vaccine in Mexican children. Our objective was to evaluate antibody response and safety of the live varicella vaccine in both healthy and immunocompromised Mexican children. METHODS: One hundred children with no history of varicella/zoster were vaccinated with a live attenuated varicella vaccine. According to their immune status, patients were divided into either a compromised (leukemia, solid tumors, chronic renal failure, and cirrhosis) or a healthy children group. Serum IgG antibodies against VZV were measured by ELISA at baseline and at 3 and 6 months after vaccination. RESULTS: A positive VZV-ELISA at baseline was detected in 36 of 67 (53.7%) immunocompromised children and in 22 of 33 (66%) healthy children. Among VZV-seronegative children, seroconversion at 6 months post-vaccination was observed in 90.3% of compromised children and in 100% of healthy children. Increases in serum antibody levels at 3 and 6 months post-vaccination was similar in both groups. VZV vaccine-related adverse reactions, mostly mild and local, were detected in 29% of the children. Three compromised children had a mild rash symptomatic of varicella after vaccination. CONCLUSIONS: About 50% of immunosuppressed children (mean age 8.8 +/- 3.6 years) with no varicella history were VZV-seronegative. Almost all of these compromised VZV-seronegative patients seroconverted 6 months after vaccine. In addition, antibody titers were similar in both compromised and healthy children.

[Cryptosporidium parvum infection in malnourished and non malnourished children without diarrhea in a Mexican rural population]. / Infección por Cryptosporidium parvum en niños desnutridos y no desnutridos sin diarrea en una población rural mexicana.

UNLABELLED: Cryptosporidium parvum is associated with diarrheic disease and mainly affects children and immunocompromised hosts. In most of the cases, cryptosporidiosis infection is asymptomatic in immunocompetent subjects. The objectives of the study were to determine the frequency of asymptomatic infection caused by the parasite in children with and without malnutrition and to determine the risk factors associated to infection. METHODS: Children from one to fifteen years old without diarrhea were included, somatometry were performed. The socioeconomic and sanitary conditions were investigated for each family and community. The Faust method and Kinyoun stain were employed identify parasites and Cryptosporidium parvum in feces. Odds ratio (OR), 95% confidence intervals (75% CI), chi 2 Mantel-Haenszel, Fisher exact test and chi 2 trends were calculated. RESULTS: One hundred thirty two children were included. In 10/132 (7.5%) cysts of Cryptosporidium were found, 7/71 in children with malnutrition (9.8%) and 3/61 without malnutrition (4.9%) p = 0.23. 69.7% of the children had parasitosis. According to the presence of C. parvum in feces, the different factors calculated were: Diarrhea in family OR = 5.82 (95%IC 0.86-39.18), not hand washing OR = 5.08 (95%IC 0.62-110.49), age less than 5 years old OR = 4.90 (95%IC 0.60-106.9), drinking non-potable water OR = 3.34 (95%IC 0.40-73.01) and malnutrition 2.11 (95%IC 0.46-10.89). Association was found between the number of people in the same house and the risk of infection (p = 0.005). The presence of diarrhea in the family (OR = 4.15, 95%IC 0.47-36.91) and drinking non-potable water (OR = 4.19, 95%IC 0.48-36.32) were the significant factors in the regression logistic model. CONCLUSIONS: The frequency of Cryptosporidium infection were 7.5%. Diarrhea in the family, overcrowding and drinking non-potable water were associated with C. parvum infection, malnutrition was not a significant risk factor.

[Nosocomial infections. Experience at a third-level pediatric hospital]. / Infecciones nosocomiales. Experiencia en un hospital pediátrico de tercer nivel.

OBJECTIVE: To describe the results of an epidemiologic surveillance program, from 1990 to the first semester of 1997, in a new high-specialty pediatric hospital and perform a comparison with previous reports. MATERIAL AND METHODS: The total number and type of nosocomial infections, the incidence rate and density incidence for department and division, for different age groups and according to immune statues were registered. RESULTS: The global incidence of nosocomial infections during the period was 25.7 per 100 discharges, with a progressive decrease during the last three years. Although immunocompromised patients had more infections than immunocompetent ones, the difference was not significative. The three most common infections were: pneumonia, vascular line infections and upper respiratory tract infections. It is possible that upper respiratory tract infections are contributing to the elevation of global incidence rates of nosocomial infections. CONCLUSIONS: The change of infection epidemiology regarding previous experience has led to the implementation of programs to prevent the most frequent problems. It is necessary to intensify the different prevention programs and to increase their reach in order to cut down costs in a short term.

[The costs of hospital infections in a group of patients in a tertiary-care hospital]. / Costos de infecciones intrahospitalarias de un grupo de pacientes en un hospital de tercer nivel de atención.

OBJECTIVE: To know the cost generated by nosocomial infections, to establish the proportion of the total hospital budget used in extra-days of stay, drugs, laboratory and others items used for the treatment. METHODS: We studied 131 nosocomial infections in 82 patients attended in hospital's departments from June to August 1995. We evaluated days of stay, type of infection, episodes per patient, drugs, laboratory, and others items used in the treatment of nosocomial infections. We took percentage of cost of every point and the mean of the total cost generated by year cause nosocomial infections and a cost per infection in every department. RESULTS: The total overtime of stay was 970 days, mean per infection was 7.4. Totals days of antimicrobials was 974, mean was 11.9 days per infection. The hospital processed 410 laboratory studies, 191 cabinet studies. The total cost generated by overtime stay was $3,415,860.00, and considering also drugs, laboratory and cabinet studies $3,516,421.00. CONCLUSIONS: The cost of the nosocomial infections depends on the overtime stay, drugs, laboratory and cabinet studies needed for their treatment. Neonatology generated presented more than one infection generating higher cost. Total cost in 3 months was $3'516,421.00, nosocomial infections would take $14'065,684.00 in a year, involving 12.1% of the hospital total budget. Preventive measures must be taken trying to diminish these costs.

Blood culture and respiratory syncytial virus identification in acute lower respiratory tract infection.

Even though the incidence of pneumonia in developed and developing countries is similar, the mortality is five times higher in developing countries. This study aimed to determine the prevalence of bacteremia in children with acute lower respiratory tract infection (LRTI) and relative contribution of respiratory syncytial virus (RSV). One hundred and one children under five years of age who attended a primary care level clinic with diagnosis of acute LRTI, were enrolled. Diagnosis and management of pneumonia were done according to the WHO guidelines. Two blood cultures were drawn at the time of admission. A nasopharyngeal sample was taken for detection of RSV by indirect immunofluorescence. Blood cultures were positive for pathogenic bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus) in three patients. The detection for RSV was positive in 24 patients (23.7%). The clinical and radiographic presentations were not significantly different between patients with and without RSV (p > 0.05). RSV is a common cause of LRTI in children younger than five years old. Blood cultures are not commonly positive in outpatients with acute LRTI. The practice of obtaining blood cultures in primary and secondary care clinics is not useful to guide the treatment of patients with community-acquired pneumonia.

Predominance of the multiresistant 23F international clone of Streptococcus pneumoniae among isolates from Mexico.

During a surveillance study to determine the relative prevalence of capsular types of Streptococcus pneumoniae and antimicrobial susceptibility of invasive isolates in children <5 years old in Mexico City, 220 isolates were collected. The serotype 23F was the most common found, followed by types 6A + B, 14, 19F, and 19A. Diminished susceptibility to penicillin was detected in 106 isolates (48.2%), and high penicillin resistance was found in 49 strains (22.2%), 31 belonging to type 23F. Resistance was also observed to erythromycin (13.1%), to chloramphenicol (43.1%), and to cefotaxime (10.9%). No strains were resistant to ofloxacin or vancomycin. Forty-four of the highly penicillin resistant isolates (penicillin MIC > or =2.0 microg/ml) were examined with molecular fingerprinting techniques; 29 (65.9%) of these isolates (all except two strains) were serotype 23F and shared subtype variants of PFGE type A characteristic of the internationally spread Spanish/USA clone of S. pneumoniae. These strains were also resistant to trimethoprim/sulfametoxasole (TMP/SMX), chloramphenicol, and tetracycline, and most of them were susceptible to erythromycin. Another 6 of the highly penicillin-resistant strains (serogroups 9 and 14) showed PFGE fingerprints and antimicrobial susceptibility pattern characteristic of a second internationally spread clone (French/Spanish clone) and carried resistance to penicillin and TMP/SMX. The rest of the 9 penicillin-resistant isolates were represented by 7 distinct additional PFGE types. The findings suggest that almost 80% of all highly penicillin resistant strains may have been "imported" into Mexico.

[Case-control study of an outbreak of S. marcescens in a neonatal intensive care unit]. / Estudio de casos y controles en un brote de S. marcescens en una unidad neonatal de cuidados intensivos.

OBJECTIVE: To analyze an outbreak of Serratia marcescens in a neonatal intensive care unit and identify the risk factors associated to the development of infection. MATERIAL AND METHODS: It was a case-control study from March to July 1995. Factors included were age, sex, intravascular devices, nebulizers, mechanical ventilation, use of total parenteral nutrition (TPN), underlying diseases, surgical interventions, tubes, previous antimicrobial treatment and days of exposure. The associations were explored using the odds ratio. RESULTS: 24 cases and 30 controls were included. In the univariate analysis the significant risk factors (OR,IC) were use of central venous catheter (4.57, 1.01-23.5), days of use of TPN (4.38, 1.03-16.5), days of previous antimicrobial treatment (4.87, 1.60-22) and days of exposure (2.7, 2.65-27.6). In the multivariate analysis the significant risk factors were previous antimicrobial treatment (3.98, 2.36-18.2), days of previous antimicrobial treatment (6.76, 3.02-24.6) and days of use of TPN (4.87, 1.67-15.6). CONCLUSIONS: The significant risk factors in our study were previous antimicrobial treatment, days of antimicrobial and days of use of TPN.

A blood micro-culture system for the diagnosis of bacteremia in pediatric patients.

The aim of this study was to evaluate the utility of a volume-modified blood culture system to diagnose bacteremia in newborns and infants. A total of 793 paired blood cultures, obtained from 464 patients (173 newborns and 291 infants), were analyzed. Vacutainer tubes containing 18 ml supplemented peptone broth sodium-polyanethol-sulfonate were used as the gold standard, in comparison with a blood micro-culture system containing 1.8 ml of the broth. Prior to antibiotic treatment, 2.2 ml of blood was obtained from each patient; 0.2 ml was inoculated in a blood micro-culture tube and 2 ml in a routine tube. Sensitivity, specificity and predictive values were calculated. Microorganisms were isolated in 153 standard blood culture tubes and 151 blood micro-culture tubes. The sensitivity of the blood micro-culture system was 95%, specificity 99% and positive and negative predictive values 96% and 99% respectively. The sensitivity and specificity of blood micro-culture in neonates and infants is high. We recommend that this system be used for the diagnosis of bacteremia in newborns and infants in laboratories where manual systems are still in use.

Antimicrobial susceptibilities and capsular types of invasive Streptococcus pneumoniae isolated in children in Mexico City.

As part of the Sistema Regional de Vacunas (SIREVA) initiative, we conducted a surveillance study to determine the relative prevalence of capsular types of Streptococcus pneumoniae and antimicrobial susceptibility of invasive isolates in children less than 5 years old. We collected 220 isolates and found 33 of the 90 known types, with type 23F as the most common followed by types 6A+B, 14, 19F, and 19A. High penicillin resistance was found in 49 strains (22.2%), 31 belonging to type 23F. Twenty-nine (13.1%) were resistant to erythromycin, 95 (43.1%) were resistant to chloramphenicol, and 24 (10.9%) were resistant to cefotaxime. No strains were resistant to vancomycin.

Streptococcus pneumoniae: low frequency of penicillin resistance and high resistance to trimethoprim-sulfamethoxazole in nasopharyngeal isolates from children in a rural area in Mexico.

Due to the changes in the frequency of penicillin-resistant strains of S. pneumoniae, it is necessary to perform surveillance studies of bacterial resistance. Isolates from the upper respiratory tract of asymptomatic children have been useful. There is no information about the difference between isolates from children with and without upper respiratory tract infection (URTI). The objective of the authors in this paper is to establish the prevalence of carrier-state, serotype and antimicrobial resistance of S. pneumoniae isolates from children with and without acute upper respiratory tract infection (URTI) in a rural area in Mexico. A cross-sectional comparative study was performed in Tlaxcala, Mexico. Children from one month 5 years of age were included. Nasopharyngeal swabs were obtained. Identification was done by international microbiology standards. Serotyping was done by the capsular Quellung test. The susceptibility testing was performed by the agar dilution method. Four-hundred and fifty patients were included. S. pneumoniae was isolated in 134 children (29.7%). Frequency of carriers was greater in patients with URTI (107/323) than without URTI (27/127) (33.1% vs. 21.1% p = 0.012, OR 1.84, IC 95% 1.1-3.08). The six most frequent serotypes were: 6B (16.4%); 19F (11.9%); 19A (6.7%); 14, 23F, and 35 (5.2% each), with no difference among the groups. Only 3% of the strains had high level resistance to penicillin, and 12.6% had intermediate resistance, and for ampicillin 4%, amoxicillin 4%, amoxicillin-clavulanate 4%, ceftriaxone 3%, cefotaxime 1.5%, erythromycin 6%, miocamycin 3%, chloramphenicol 4%, and vancomycin 0%. Trimethoprim-sulfamethoxazole resistance was very high (42%). In conclusion, colonization is higher in children with URTI. Five of the most frequent serotypes identified in this study were the same as those identified in patients with S. pneumoniae invasive diseases in Mexico City. In Tlaxcala, Mexico, beta-lactams could be the drug of choice for the treatment of S. pneumoniae lower respiratory tract infections. It is necessary to perform clinical assays to evaluate the efficacy of trimethoprim-sulfamethoxazole due to the high resistance in vitro.

Comparison of five methods for the detection of measles specific immunoglobulin G antibody.

In this work we compare the sensitivity, specificity and predictive values of hemagglutination inhibition (HI), immunofluorescent assay (IFA), biotin-streptavidin immunofluorescent assay (B/SA-IFA), enzyme-linked immunosorbent assay (EIA) and plaque neutralization test (PN). This study includes serum samples from children taken before and after vaccination, children with clinically diagnosed measles and household contacts. EIA were the most specific and better serological diagnostic test. HI and IFA had high sensitivity but low specificity. An alternative to EIA is B/SAIFA, which is cheaper than EIA and can be used in the study of small outbreaks or in isolated cases.

[Amikacin in single daily doses in children with fever]. / Amikacina en dosis única diaria en ninõs con fiebre.

A randomized clinical trial was performed in children with cancer, fever and neutropenia, to evaluate the efficacy of amikacin once daily versus thrice daily dosing plus carbenicillin in both groups. Fifty patients were included, 25 patients in group A who received amikacin once daily and 25 in group B who received amikacin thrice daily. No intergroup differences were observed, i.e., fever diminished in a median of 6 days (2-8 days) vs. 7 days (3-12 days) in groups A and B respectively (p = 0.37);clinical improvement was observed in a median of 6 days (3-10 days) vs 7 days (2-14 days) (p = 0.68). One patient in group A and two in B died. The peak levels of amikacin on the 7th day of treatment were 10-60 and 7-25 micrograms/mL in groups A and B respectively, and the serum creatinine levels were 0.3 - 0.7 for group A and 0.2 - 0.8 mg/dL for group B; none of the patients presented a creatinine above 40% of the basal value. Three patients of group A had amikacin levels higher than 40 micrograms/mL without increasing the creatinine levels; our observations do not suggest that toxicity is higher. We conclude that the administration of aminoglycoside once daily seems to be as effective as the traditional dosing.