Immediate treatment of acute HIV in a tertiary healthcare center: bridging gaps in communication using smartphones

OBJECTIVES

Early initiation of antiretroviral therapy (ART) during acute HIV infection is associated with favourable clinical and epidemiological outcomes. Barriers to prompt treatment initiation limit the benefits of universal access to ART in Mexico. We sought to create an algorithm for the immediate detection and treatment of patients with acute HIV infection.

METHODS

A nationwide cohort of patients with acute HIV infection was created in 2015. In order to identify cases and treat them promptly at our centre, an interdisciplinary group coordinated through an instant-messaging tool using smart phones was established. When a probable case was detected, a discussion was initiated to confirm the diagnosis and facilitate the administrative processes to initiate ART as soon as possible. We compared time to ART initiation with that in a comparison group of patients with chronic HIV infection enrolled during the same period (May 2015 to February 2017) through routine care, using survival analysis estimators and log-rank tests.

RESULTS

We recruited 29 patients with acute HIV infection. The median time to ART initiation was 2 days in these patients, in contrast to 21 days for patients with chronic infection. There were no significant differences in the percentages of patients engaged in care, on treatment or virologically suppressed at 1 year of follow-up.

CONCLUSIONS

Implementing immediate ART initiation programmes is feasible in Mexico, in spite of the substantial administrative barriers that exist in the country. More extensive replication of this model in other centres and in patients with chronic infection is warranted to evaluate its effect on the continuum of care.

[Antibiotic therapy in secondary peritonitis: towards a definition of its optimal duration]

BACKGROUND

The optimal time period of antibiotic treatment in secondary peritonitis is still unknown.

AIM

To prospectively evaluate: 1) The preferred time period of antibiotic treatment in secondary peritonitis by means of a survey applied to a sample of surgeons, and 2) The outcome of a series of patients with secondary peritonitis in whom the length of antibiotic treatment was based on clinical and laboratory indicators.

PATIENTS AND METHODS

A survey presenting the case of a patient with acute appendicitis and secondary peritonitis was applied to 100 Mexican surgeons. The optimal length of antibiotic treatment in that particular patient was asked. Results were tabulated and analyzed. Subsequently, 35 patients with secondary peritonitis were prospectively evaluated. Antibiotics were discontinued when fever relapsed and the white blood count normalized. Clinical characteristics, diagnosis, surgical treatment and outcome were analyzed. Recurrence of sepsis was investigated as the main outcome variable.

RESULTS

The survey revealed that 96% surgeons recommended antibiotic treatment for a period longer than one week. In our study group median age was 33 years, 21 were male and 14 female. All patients had a surgical abdominal condition associated to secondary peritonitis. Median period of antibiotic treatment was 3 days. In a follow-up of one month there was no persistent or recurrent sepsis in any patient.

CONCLUSIONS

This information may impact in determining the total length of antibiotic therapy if our results are reproduced in studies with more patients.

Helicobacter pylori in water systems for human use in Mexico City

Helicobacter pylori infection is associated with peptic ulcers and gastric cancer in humans. Transmission of H. pylori is still not certain with some epidemiological data suggesting water as a possible transmission route. The objective of this study was to detect H. pylori 16S rRNA gene in five water systems in the Mexico City area. Samples were taken between 1997 and 2000 from extraction wells (system 1), from dams used as water sources, both pre- and post-treatment (systems 2 and 3), treated wastewater (system 4) and non-treated wastewater (system 5). Detection of the H. pylori 16S rRNA gene in water samples was carried out using nested PCR in 139 water samples and confirmed by using cagA gene detection by PCR-hybridisation. The results showed the presence of H. pylori in 58 (42%) of the water samples in total with a prevalence of 68% in system 1, 100% in system 2, 0% in system 3, 17% in system 4 and 20% in system 5. This first stage showed the presence of H. pylori in the tested water systems; nevertheless, viability of the microorganism in water and vegetables needs to be confirmed as well as demonstration of a relationship between human and environmental strains.

Serum antibody as a marker of protection against natural rotavirus infection and disease

To determine whether naturally acquired serum IgA and IgG antibodies were associated with protection against rotavirus infection and illness, a cohort of 200 Mexican infants was monitored weekly for rotavirus excretion and diarrhea from birth to age 2 years. Serum samples collected during the first week after birth and every 4 months were tested for anti-rotavirus IgA and IgG. Children with an IgA titer >1:800 had a lower risk of rotavirus infection (adjusted relative risk [aRR], 0.21; P<.001) and diarrhea (aRR, 0. 16; P=.01) and were protected completely against moderate-to-severe diarrhea. However, children with an IgG titer >1:6400 were protected against rotavirus infection (aRR, 0.51; P<.001) but not against rotavirus diarrhea. Protective antibody titers were achieved after 2 consecutive symptomatic or asymptomatic rotavirus infections. These findings indicate that serum anti-rotavirus antibody, especially IgA, was a marker of protection against rotavirus infection and moderate-to-severe diarrhea.

Geographic differences in bone mineral density of Mexican women

The aim of this study was to generate standard curves for normal spinal and femoral neck bone mineral density (BMD) in Mexican women using dual-energy X-ray absorptiometry (DXA), to analyze geographic differences and to compare these with 'Hispanic' reference data to determine its applicability. This was a cross-sectional study of 4460 urban, clinically normal, Mexican women, aged 20-90 years, from 10 different cities in Mexico (5 in the north, 4 in the center and 1 in the southeast) with densitometry centers. Women with suspected medical conditions or who had used drugs affecting bone metabolism, were excluded. Lumbar spine BMD was significantly higher (1.089 +/- 0.18 g/cm2) in women from the northern part of Mexico, with intermediate values in the center (1.065 +/- 0.17 g/cm2) and lower values (1.013 +/- 0.19 g/cm2) in the southeast (p < 0.0001). Similarly, femoral neck BMD was significantly higher in women from the north (0.895 +/- 0.14 g/cm2), intermediate in the center (0.864 +/- 0.14 g/cm2) and lower (0.844 +/- 0.14 g/cm ) in the southeast part of Mexico (p < 0.0001). Northern Mexican women tend to be taller and heavier than women from the center and, even more, than those from the southeast of Mexico (p < 0.0001). However, these differences in BMD remained significant after adjustment for weight (p < 0.0001). A significant loss (p < 0.0001) in BMD was observed from 40 to 69 years of age at the lumbar spine and up to the eighth decade at the femoral neck. Higher and lower lumbar spine values, as compared with the 'Hispanic' population, were observed in Mexican mestizo women from the northern and southeastern regions, respectively. In conclusion, there are geographic differences in weight and height of Mexican women, and in BMD despite adjustment for weight.

Epidemiological and biological characteristics of methicillin-resistant staphylococcal infections in a Mexican hospital

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has spread worldwide since 1960. However, there is little information concerning methicillin-resistant coagulase-negative staphylococci (MRCNS) infections.

METHODS

In order to study the clinical and epidemiological characteristics of methicillin-resistant staphylococci (MRS) infections and to determine the relationship between MRS and both synergistic hemolysis (SH) and slime production (SP), a laboratory-based survey and non-matched case-control study were carried out at a tertiary-care center in Mexico City. In regard to patients, from May 1991 to October 1992, 46 cases of MRS infection and 86 patients (controls) infected by methicillin-susceptible staphylococci (MSS) were included. Clinical and epidemiologic variables were analyzed. The isolates were identified and tested for antimicrobial susceptibility by standard methods. An MIC of oxacillin > or = 8 micrograms/mL was defined as an MRS.

RESULTS

During the study, 94 nosocomial staphylococcal infections were diagnosed: S. aureus, 35 and CNS, 59; 43 (45.7%) by MRS (rate of MRS infections was 1.12 per 100 in-patients); 2 MRSA; 41 MRCNS, and only 19 were symptomatic. Three infections were community-acquired, including one MRSA and two MRCNS. After multivariate analysis, the significant risk factors were previous antimicrobial therapy (p = 0.013) and catheter-related (p = 0.009) and urinary-tract source (p = 0.0001). Forty-nine percent of MRS showed SH while only 15% of MSS (p < 0.001) showed SH, especially in 10/10 MR-S. hemolyticus. Additionally, 48% of MRCNS showed SP, as did 18% of MSCNS (p = 0.019), particularly in 15/20 MR-S. epidermidis. Of all MRS isolates, 38% showed a homogeneous phenotype, a trait associated with multi-drug resistance (p < 0.01) and SH (p < 0.001).

CONCLUSIONS

CNS predominated as the cause of MRS infections in our setting. The homogenous phenotype was associated with SH and multi-drug resistance.

Efficacy of home-based peer counselling to promote exclusive breastfeeding: a randomised controlled trial

BACKGROUND

Exclusive breastfeeding is recommended worldwide but not commonly practised. We undertook a randomised controlled study of the efficacy of home-based peer counselling to increase the proportion of exclusive breastfeeding among mothers and infants residing in periurban Mexico City.

METHODS

Two intervention groups with different counselling frequencies, six visits (44) and three visits (52), were compared with a control group (34) that had no intervention. From March, 1995, to September, 1996, 170 pregnant women were identified by census and invited to participate in the study. Home visits were made during pregnancy and early post partum by peer counsellors recruited from the same community and trained by La Leche League. Data were collected by independent interview. Exclusive breastfeeding was defined by WHO criteria.

FINDINGS

130 women participated in the study. Only 12 women refused participation. Study groups did not differ in baseline factors. At 3 months post partum, exclusive breastfeeding was practised by 67% of six-visit, 50% of three-visit, and 12% of control mothers (intervention groups vs controls, p<0.001; six-visit vs three-visit, p=0.02). Duration of breastfeeding was significantly (p=0.02) longer in intervention groups than in controls, and fewer intervention than control infants had an episode of diarrhoea (12% vs 26%, p=0.03).

INTERPRETATION

This is the first reported community-based randomised trial of breastfeeding promotion. Early and repeated contact with peer counsellors was associated with a significant increase in breastfeeding exclusivity and duration. The two-fold decrease in diarrhoea demonstrates the importance of breastfeeding promotion to infant health.

Rapid ethnographic assessment of breastfeeding practices in periurban Mexico City

Before carrying out a breastfeeding promotion programme in a periurban area of Mexico City, we conducted a rapid ethnographic study to determine the factors associated with absence of exclusive breastfeeding. The responses to pilot interviews were used to develop a standardized questionnaire regarding reasons for infant feeding choice, sources of advice, and barriers to breastfeeding. We interviewed a random sample of 150 mothers with a child < 5 years of age; 136 (91%) of them had initiated breastfeeding; but only 2% exclusively breastfed up to 4 months. The mothers consistently stated that the child's nutrition, health, growth, and hygiene were the main reasons for the type of feeding selected; cost, comfort, and the husband's opinion were less important. Physicians were ranked as the most important source of advice. Reduction or cessation of breastfeeding occurred on the doctor's advice (68%); or when the mothers encountered local folk illnesses such as "coraje" (52%) or "susto" (54%), which are associated with anger or fright; or had "not enough milk" (62%) or "bad milk" (56%); or because of illness of the mother (56%) or child (43%). During childhood illnesses and conditions, breastfeeding was reduced and the use of supplementary foods was increased. This study emphasizes the importance of cultural values in infant feeding choices, defines specific barriers to breastfeeding, and provides a basis for interventions to promote exclusive breastfeeding in the study population.

A prospective study of astrovirus diarrhea of infancy in Mexico City

AIM

To describe the epidemiologic and clinical characteristics of astrovirus-associated diarrhea in a cohort of young children from a periurban community in Mexico City.

METHODS

From November, 1988, through December, 1991, a total of 214 children were enrolled in a longitudinal study of diarrhea and monitored from birth to 18 months of age. A stool specimen was collected during each episode of diarrhea. Specimens from a total of 510 diarrhea episodes were tested for astrovirus by enzyme immunoassay and examined for other enteric pathogens. The antigenic types of astrovirus were determined by a typing enzyme immunoassay.

RESULTS

Astrovirus was detected in 26 (5%) of 510 diarrhea episodes, with an incidence rate of 0.1 episode/child year; the highest rate was in children 13 to 18 months of age. Astrovirus-associated diarrhea was characterized by a median of 4 stools (range, 2 to 10) during the first 24 h, a median duration of 3 days (range, 1 to 21), vomiting (20%), and fever (7%). No cases of dehydration or repeat symptomatic infections were observed. Coinfection with another pathogen was detected in 11 of the 26 episodes (42%). Serotype 2 (35%) was most common, followed by serotypes 4 (15%), 3 (11%), and 1 and 5 (4% each); 31% were nontypable. Astrovirus-associated diarrhea was less severe, as measured by the number of stools (4.3 +/- 1.9), than diarrhea caused by rotavirus (7.1 +/- 2.8) or when coinfections occurred (5.5 +/- 1.6; P = 0.008).

CONCLUSIONS

Astrovirus was associated with 5% of the episodes of diarrhea in this cohort of young Mexican children and presented as a mild secretory diarrhea. Five predominant antigenic types were detected with type 2 being the most common.

[Antibiotic resistance of Helicobacter pylori in an infectious disease referral center]

OBJECTIVE

To estimate the frequency of H. pylori clinical isolates resistant to six commonly used antimicrobials.

DESIGN

Cross-sectional observational study.

SETTING

A tertiary-referral health care institution in Mexico City.

PARTICIPANTS

31 isolates of H. pylori from 31 patients with chronic antral gastritis were obtained from gastric mucosal biopsy specimens.

MAIN OUTCOME MEASURE

The Minimum Inhibitory Concentration (MIC) to ampicillin, amoxycillin, tetracycline, doxycycline, metronidazole and to colloidal bismuth subcitrate was determined by the agar plate dilution test.

RESULTS

All isolates showed to be susceptible to the former four antibiotics but only in 46% and 55% growth was inhibited by 8 micrograms/mL and 16 micrograms/mL of metronidazole, respectively. All isolates were inhibited by < or = 128 micrograms/mL of bismuth. A 50% increase in the percentage of metronidazole-resistant isolates (MIC > or = 8 micrograms/mL) between 1988 to 1992 was observed.

CONCLUSION

There is a need of future studies in our setting aimed at assessing the cost/effectiveness of diverse H. pylori-associated peptic ulcer treatment options.

Effects of thalidomide on HIV-associated wasting syndrome: a randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

To evaluate the efficacy of thalidomide in treating wasting syndrome in patients with advanced HIV disease, and to assess the effects of thalidomide on circulating CD4+ T cells, and on HIV viral burden in peripheral blood mononuclear cells (PBMC).

DESIGN

Randomized, double-blind placebo-controlled clinical trial.

SETTING

Public tertiary care hospital in Mexico City.

PATIENTS

Twenty-eight adults with advanced HIV disease being treated with antiretroviral therapy, and who had received antiretrovirals for at least 6 months, who did not have an active opportunistic infection, and who had 10% weight loss in the previous 6 months.

INTERVENTIONS

Patients received thalidomide (100 mg by mouth, four times daily) or a matching placebo for the duration of the study (12 weeks).

MAIN OUTCOME MEASURES

The main clinical endpoint for efficacy of thalidomide was weight gain or no progression of wasting. Secondary endpoints were Karnofsky performance status, CD4+ cell counts, and HIV viral burden in PBMC.

RESULTS

Both groups were comparable in their baseline status. Therapeutic failure occurred in 10 out of 14 patients from the placebo group and in three out of 14 from the thalidomide group (P = 0.021). Weight gain occurred in one patient on placebo and in eight given thalidomide. The Karnofsky index was significantly higher by the end of the study in the thalidomide group (P = 0.003). Mild and transient somnolence and erythematous macular skin lesions were significantly more common in the thalidomide group. CD4+ T cell counts and HIV viral burden in PBMC did not change in either group.

CONCLUSIONS

Results suggest that thalidomide not only impeded but also reverted the wasting syndrome, preserving the Karnofsky index in patients with advanced HIV disease. Thalidomide, at the dosage used in this study, had no effect on peripheral CD4+ T cells nor on HIV viral burden in PBMC.

Rotavirus infection in infants as protection against subsequent infections

BACKGROUND

Rotavirus is the leading cause of severe diarrhea in infants. To provide a base line for assessing the efficacy of rotavirus vaccines, we evaluated the protection that is conferred by natural rotavirus infection.

METHODS

We monitored 200 Mexican infants from birth to two years of age by weekly home visits and stool collections. A physician assessed the severity of any episodes of diarrhea and collected additional stool specimens for testing by enzyme immunoassay and typing of strains. Serum collected during the first week of life and every four months thereafter was tested for antirotavirus IgA and IgG.

RESULTS

A total of 316 rotavirus infections were detected on the basis of the fecal excretion of virus (56 percent) or a serologic response (77 percent), of which 52 percent were first and 48 percent repeated infections. Children with one, two, or three previous infections had progressively lower risks of both subsequent rotavirus infection (adjusted relative risk, 0.62, 0.40, and 0.34, respectively) and diarrhea (adjusted relative risk, 0.23, 0.17, and 0.08) than children who had no previous infections. No child had moderate-to-severe diarrhea after two infections, whether symptomatic or asymptomatic. Subsequent infections were significantly less severe than first infections (P=0.024), and second infections were more likely to be caused by another G type (P=0.054).

CONCLUSION

In infants, natural rotavirus infection confers protection against subsequent infection. This protection increases with each new infection and reduces the severity of the diarrhea.

Antimicrobial resistance in fecal flora: longitudinal community-based surveillance of children from urban Mexico

We assessed the colonization patterns, over time, of three sentinel drug-resistant enteric bacterial genera in samples from a cohort of 20 healthy small children in a periurban community in Mexico. The children were monitored during a 13-week period by means of weekly home visits and examinations of stool collections. These specimens were tested for the presence of Escherichia coli, Klebsiella species, and Shigella species resistant to one or more of seven antimicrobial agents. Ninety, 77, and 62% of the stool specimens had E. coli isolates resistant to ampicillin, trimethoprim, and tetracycline, respectively. Simultaneous resistance to more than one antibiotic by an E. coli isolate was observed in 88.5% of stool samples. Persistent fecal shedding of ampicillin-, trimethoprim-, and tetracycline-resistant E. coli occurred during the study period in the majority of children. We detected colonization by E. coli resistant to chloramphenicol, gentamicin, nitrofurantoin, or norfloxacin, as well as by Klebsiella species and Shigella species resistant to one of these antibiotics, in fewer children and for shorter periods. These data suggest the common and persistent intestinal shedding of multidrug-resistant E. coli strains by small healthy children.

Polymerase chain reaction for the detection of Mycobacterium tuberculosis DNA in tissue and assessment of its utility in the diagnosis of hepatic granulomas

A polymerase chain reaction (PCR) assay for the rapid identification of Mycobacterium tuberculosis, based on amplification of the IS6110 insertion sequences, was tested in paraffin-embedded tissue from 64 biopsy samples with either positive or negative cultures for Mycobacterium tuberculosis. The utility of this PCR assay in the diagnosis of tuberculosis among patients with hepatic granulomas (HGs) was then tested by examining 43 liver biopsy samples. They were classified as either having definitive or probable tuberculosis or as being of nontuberculous origin, on the basis of clinical and microbiologic data and on their response to antituberculous treatment. PCR was 100% sensitive in the diagnosis of culture-positive M. tuberculosis infection in the lymph node, lung, and liver. The sensitivity of the PCR in the diagnosis of HG of definitive tuberculous origin was 58%, and the specificity was 96%. PCR is a valuable test for the demonstration of mycobacterial DNA in tissues. Although it is not highly sensitive, the DNA amplification method may also be more sensitive than culture in the diagnosis of M. tuberculosis-associated HG.

Study of Norwalk-related viruses in Mexican children

Two-hundred Mexican children monitored from birth to 2 years of age in a cohort study of diarrhea were tested for Norwalk virus (NV) and Norwalk-related virus infection. Blood was collected quarterly and tested by an enzyme immunoassay (EIA) using the recombinant NV (rNV) particles as antigen. Stool was collected weekly and tested by an EIA using hyperimmune anti-sera from animals immunized with rNV and a reverse transcription-polymerase chain reaction (RT-PCR) with primers in the RNA polymerase region of NV. A high prevalence of serum antibody to NV (85% at age 2 years) was found by the antibody EIA. In 54 stool specimens selected from children who developed a high titer of serum antibody to rNV, none was positive for NV by the antigen EIA, but 6 yielded products by the RT-PCR. One stool specimen (MX virus) yielded a 3.3 kb RT-PCR product from the 3' end of the viral genome. The MX virus cDNA has a genomic organization like other caliciviruses. Sequence comparison showed that MX virus shares 80% nucleic acid and 91% amino acid sequence identity with Snow Mountain agent (SMA), but only 62% and 60% identity, respectively, with NV in the RNA polymerase region, suggesting that MX virus is a SMA-like virus.

[Utility of thoracic teleradiography in hospitalized patients]

AIM

To assess the utility of the chest roentgenogram (CR) in hospitalized patients in terms of its diagnostic and therapeutic influence on the clinician.

DESIGN

A survey in a group of residents of internal medicine at a tertiary care teaching hospital was carried out. Two questionnaires were applied: one when a follow-up CR was ordered (inquiring about reasons for ordering the film, the likelihood that the CR would show changes and physician's therapeutic plan); the second questionnaire was applied after the CR was obtained (inquiring about how unexpected the CR finding was and its degree of influence on therapy). Both questionnaires were analyzed in regard to the CR interpretation by a radiologist.

RESULTS

One hundred surveys were analyzed. CR ruled out the suspicion of a new pulmonary event (55% of cases) or of the worsening of a known lung disease (50%) as predicted by the physician. In turn, CR confirmed the absence of a new pulmonary event (92%), or the improvement/stabilization of the course of a known lung disease (92%), as predicted by the physician. Sixty-one percent of these CR had a definite influence on patients' treatment.

CONCLUSION

CR in hospitalized patients is of practical benefit to physicians, mainly in avoiding overdiagnosis and unnecesary treatment to their patients.

Asymptomatic Shigella infections in a cohort of Mexican children younger than two years of age

The proportion of Shigella infections that occur asymptomatically in young children has not been established. A community-based cohort study of 367 infants was followed prospectively by weekly home visits from January, 1990, through December, 1991. Stool samples were collected weekly and when diarrhea occurred and were tested for Shigella and other enteropathogens. There were 2925 child months of observation and 65 episodes of Shigella infection. There were 3.1 episodes/100 child months during the warm season (May through September) and 0.97 episode/100 child months during the cold season. Shigella infections were rare during the first 6 months of life but increased with age (P < 0.0001). Overall 55% of detected infections were asymptomatic. The proportion of infections that were asymptomatic increased as age increased (P < 0.01). Symptom status was not significantly associated with Shigella species or season. All isolates from symptomatic and asymptomatic children had the 120- to 140-megadalton virulence plasmid. We conclude that infections with virulent strains of Shigella are commonly asymptomatic in Mexican children during the first 2 years of life.

Antibiotic misuse in diarrhea. A household survey in a Mexican community

A survey of 1659 households in a periurban community in Mexico City was carried out to assess the frequency of and risk factors for inappropriate antimicrobial therapy in acute diarrhea. The housewife was interviewed to obtain information of the occurrence of diarrhea or use of an antibiotic in the previous 2 weeks by any member of the family. An antibiotic was used in 37% or 287 diarrheal episodes although only in 5% of all episodes was this therapy indicated, based on the presence of gross blood in stools. Patients seen by a physician were 6 times more likely to be treated with an antibiotic compared to those who did not consult a physician (p < 0.001). Self-medication was associated with a higher risk of using an inadequate drug or dose (in 72% of treated episodes) and of following treatment for less than 5 days (in 66% of treated episodes). Other risk factors significantly and independently associated with antibiotic misuse were: an increased number of stools (odds ratio [OR] = 1.21; 95% confidence interval [CI] = 1.04, 1.41), bloody diarrhea (OR = 19.04; 95% CI = 2.52, 160.90) and family crowding (OR = 2.07; 95% CI = 1.17, 3.63). These findings support future community-oriented educational interventions aimed at improving physician prescribing practices and patient compliance behavior in order to achieve a more rational use of antibiotics.

[Antibiotic consumption in a community of Mexico City. II. Survey of purchases at pharmacies]

In developing countries, antibiotics are the most common sales of drugs and it has been suggested that their irrational use leads to the emergence of resistant bacteria. In order to assess the purchase of antimicrobials in a peri-urban community in Mexico City six local drug stores were randomly selected. A social worker made five visits to each pharmacy and she observed the events during the purchase of the drug and applied a structured questionnaire to the customer immediately after the transaction. Antibiotics were the majority (29%) of the drug sales. Of all purchasers of an antibiotic 43% did it without medical prescription and 72% answered that a physician had influenced on the purchase. Duration of the antibiotic therapy was specified in one out of three prescriptions that were examined and only in 28% of the sales the purchase was enough for a treatment duration of more than four days. More information, from similar surveys in drug stores in other settings, is needed to support the reinforcement of actions to control the sales of antibiotics in the community.

[The use of antibiotics in a community of Mexico City. I. A household survey]

Based on previous community-oriented studies an irrational use of antibiotics, particularly in developing countries, has been suggested. In order to describe the pattern of antibiotic use in a periurban community in Mexico City, 1659 randomly selected households were visited and an interview to the housewife was carried out. Of 8279 individuals 425 (5%) had used at least one antimicrobial in the preceding two weeks. Main perceived reasons for drug use were: respiratory tract ailments (58%) and acute diarrhea (25%). Antibiotic therapy was given in 27% of respiratory diseases and in 37% of all diarrheal episodes. Most commonly used drugs were: penicillins (43%), erythromycin (13%), metronidazole (9%), neomycin (6%), cotrimoxazole (6%) and tetracyclines (6%). While self-medication was common (19%) the majority of antibiotics were prescribed by a physician (81%). Approximately two thirds of individuals using an antibiotic did it for less than five days. Our data suggest a frequent misuse of antibiotics and support the future assessment, in this community, of physician prescribing practices, the determinants of self-medication as well as the impact of this drug use on the selection of resistant bacterial strains.

Cohort study of rotavirus serotype patterns in symptomatic and asymptomatic infections in Mexican children

A cohort of 200 Mexican children from a low income periurban community was monitored from birth to the age of 2 years to determine the serotype-specific incidence, morbidity and seasonal pattern of symptomatic and asymptomatic human rotavirus (HRV) infections. A total of 177 HRV infections occurred in 134 (67%) children; 50% of these infections were asymptomatic. The incidence of all HRV infections was 0.6 episode/child year and was inversely related to age (r = -0.93; P < 0.01). The incidence of HRV-associated diarrhea was 0.3 episode/child year, with the highest frequency and severity occurring in infants between 4 and 6 months of age. HRV infections were more frequent each autumn, with a changing sequential pattern of predominant serotypes. Overall serotype 3 (34%) was the most frequent, followed by serotypes 1 (16%), 2 (15%) and 4 (6%). The 4 serotypes were associated with a similar risk for diarrhea and severity of diarrhea. In 23 (26%) HRV diarrhea-associated infections, an additional enteropathogen was identified; these mixed infections were more frequent in older children (chi square, 4.45; P < 0.05) but were not more severe (chi square, 0.02; P > 0.05). Our data indicate that HRV infections were common early in life, seasonal, frequently asymptomatic and caused by a variety of serotypes, none of which was a risk factor for diarrhea or severity of diarrhea.

[Usefulness and risks of transtracheal aspiration in the diagnosis of pulmonary infections]

OBJECTIVE

To define the diagnostic usefulness and the risks of the transtracheal aspirate in a group of patients studied at the National Institute of Nutrition in Mexico City.

DESIGN

It is a retrospective and descriptive analysis of a group of patients in whom a transtracheal aspiration (TTA) was performed due to suspicion of pulmonary infection. The study period was from 1983 to 1987.

PATIENTS

On the study period 137 patients were submitted to a TTA; the clinical files of 126 of the cases were considered suitable for analysis.

RESULTS

The procedure was performed because of a suspected bacterial pneumonia in 80% of the cases, and to study an interstitial infiltrate or pulmonary nodules in 14% and 6%, respectively. In the cases in which a bacterial pneumonia was suspected, the TTA had a sensitivity of 77% and a specificity of 95% when compared against a group of clinical, radiologic and microbiological data. Sensitivity increased to 84% when the patients who received antibiotics prior to the procedure were excluded. The specificity of the sputum's culture was sensibly less in this same group of patients. The TTA proved to be of value in five of nine pulmonary tuberculosis, two of three pulmonary mycoses and three of seven P. carinii pneumonias. Adverse events were noted in 6.3% of the cases; none of them was fatal, and specific corrective measures were necessary in only two patients.

CONCLUSIONS

Our results agree with previous reports related to the usefulness of the TTA on patients with a suspected bacterial pneumonia. Our specificity is higher than that seen by other authors: we believe this is due to the low incidence of chronic respiratory diseases in the patients who attend our hospital. Transtracheal aspirate can be a valuable alternative in the diagnosis of non-bacterial pulmonary infections when the elective procedures cannot be performed. A modification on the technique is proposed to increase its usefulness in patients with interstitial pneumonia.

Hospital-acquired diarrhea in adults: a prospective case-controlled study in Mexico

OBJECTIVE

To know the incidence, etiology, risk factors, morbidity, and mortality of nosocomial diarrhea in adults.

DESIGN

Nested case-control study, matched by service, length of stay, date of admission, and presence of leukopenia and/or the acquired immunodeficiency syndrome (AIDS). Cases were those who developed nosocomial diarrhea. Controls were those who did not develop nosocomial diarrhea during a comparative period nor during the next ten days. Stool samples were processed in search for parasites, yeasts, bacteria, and rotavirus.

SETTING

Third-level referral center, in Mexico City, Mexico, for general internal medicine and surgical problems.

PATIENTS

Eligible subjects were all new admissions to the hospital from November 1987 to September 1988. Reasons for exclusion were presence of chronic diarrheal disease or melena. There were 115 cases and 111 controls.

RESULTS

Overall risk of acquiring nosocomial diarrhea was 5.5%, or 1.8 episodes per 100 patient-weeks. A potential pathogen was found in 59%. Yeasts and Entamoeba histolytica were the most frequently isolated pathogens. Mortality in cases was 18%, as compared with 5% in controls (p less than .01). Multivariate analysis showed enteral feeding, recent enemas, presence of Candida species, use of antacids/H2-blockers, and presence of nasogastric tubes as significant risk factors for nosocomial diarrhea.

CONCLUSIONS

Diarrhea is a common complication in hospitalized patients. It occurs more often than previously suspected and is linked with a substantial mortality. The spectrum of etiologic agents is different from that reported in pediatric hospitals. Given that nosocomial diarrhea may constitute, at least, a marker of severity of illness, it should receive more attention in general hospitals.

Human milk secretory immunoglobulin A to Shigella virulence plasmid-coded antigens

Although antibodies to the lipopolysaccharide antigens of Shigella have been demonstrated in human milk, such antibodies do not explain the putative protective effect of breast-feeding against symptomatic Shigella infection. Shigella species do not share related lipopolysaccharides, but they do possess closely related virulence plasmids that code for the proteins essential for cell invasion. We therefore sought to determine the frequency, amount, and duration of excretion of human milk antibodies to these shared virulence plasmid-associated antigens in populations of different rates of Shigella infection frequency (Mexico City, high; Houston, low). Such antibodies were present in the milk of virtually all the Mexican women but also were present in a large proportion of milk samples from the women living in Houston. The amounts of these antibodies were highest in colostrum but after 2 weeks of lactation fell to stable levels. The frequency and persistence of these antibodies in the milk of the women from Houston suggest that the memory and drive for secretion of these antibodies is extremely long lived.

Diagnostic laparotomy in fever of unknown origin

Twenty five consecutive patients with fever of unknown origin (FUO) who underwent diagnostic laparatomy (DL) are reviewed. There were 14 females and 11 males, with a mean age of 34 years. The main symptoms and signs besides fever were malaise, weight loss, varied abdominal complaints, peripheral lymph nodes enlargement, hepatomegaly and splenomegaly. The main laboratory abnormalities were: anemia, leukocytosis, and mild alterations in liver function tests. CT scan was performed in 14 patients: hepatomegaly, splenomegaly and or retroperitoneal nodes were found in 10 of them. During laparotomy, an extensive exploration of intra-abdominal organs was performed, taking multiple biopsies for histopathologic and microbiologic analysis. Splenectomy was performed in 17 patients, prophylactic appendectomy in four, and cholecistectomy in one. Laparotomy was useful to establish a diagnosis in 64 percent of cases. The most frequently diagnosed pathologies were lymphoma and tuberculosis. Postoperative morbidity was 12% and mortality was 4%. Mean follow-up was 29 months. When preoperative data were analyzed, no predictive factors were found for a laparotomy with diagnostic success. It is concluded that DL is a useful last-step procedure in the diagnostic work-up for patients with FUO.

Enterotoxins and adhesins of enterotoxigenic Escherichia coli: are they risk factors for acute diarrhea in the community?

A cohort of 228 Mexican children less than 5 years old was followed during the enterotoxigenic Escherichia coli(ETEC) season. The incidence of ETEC diarrhea-associated and asymptomatic infections was determined, and E. coli strains isolated from stool samples were tested for heat-labile and heat-stable toxins and for expression of colonization factor antigens (CFA). Of the children, 61% had at least one ETEC infection. Children with ETEC isolated from stools were more likely to have diarrhea than were ETEC-free age-matched control children (odds ratio [OR] = 4.5; 95% confidence interval [CI] = 2.9-7.0). Strains carrying CFA/IV, CFA/I, or CFA/II were found in 23%, 18%, and 5% of ETEC infections, respectively. The risk of having diarrhea associated with a CFA-expressing versus a CFA-negative ETEC strain was the same (age-adjusted OR = 0.8; 95% CI = 0.4-1.6). These data should be considered in the development of a diarrhea vaccine containing only CFAs.

Protection of breast-fed infants against Campylobacter diarrhea by antibodies in human milk

To investigate the role of breast-feeding in preventing diarrhea caused by Campylobacter jejuni, we followed 98 Mexican children prospectively for 2 years beginning at their birth. Attack rates of diarrhea in children less than 6 months of age who were not fed human milk were 2.3 times greater than those in children of the same age who were fed human milk. Breast-fed children remained free of diarrhea for a longer time than non-breast-fed children (p less than 0.0005). The diarrhea attack rate caused by C. jejuni for non-breast-fed infants was significantly greater (p less than 0.005) than that in the breast-fed group. Secretory IgA milk antibody titers against glycine acid-extractable antigen of C. jejuni were high in colostrum, decreased during the first month of breast-feeding, and generally persisted throughout lactation. Human milk consumed by children in whom Campylobacter diarrhea developed did not contain secretory IgA antibodies to the glycine acid-extractable common antigen of Campylobacter. This study shows an association between Campylobacter antibodies in human milk and prevention of diarrhea caused by Campylobacter.

Human milk immunoglobulin A antibodies to Shigella virulence determinants

Because human milk is thought to protect infants from shigellosis, we evaluated milk for immunoglobulin A to Shigella virulence determinants. Milk was preincubated to remove antibodies unrelated to each locus of interest, using defined Shigella and E. coli hybrids containing known Shigella genetic segments prior to immunoblotting. The milk could not be shown to contain antibodies to chromosomally encoded virulence loci except for the expected antibodies to the products of the histidine locus. However, all the milk samples contained antibodies to antigens encoded by the large virulence plasmid. The finding of these antibodies suggests a possible mechanism by which human milk might protect infants.

Cohort study of intestinal infection with campylobacter in Mexican children

A cohort of 179 children under 5 years of age from a low-income urban community was followed up for a year to determine the incidence of symptom-producing and of diarrhoea-free campylobacter intestinal infections, and thus their illness-to-infection ratio. 66% of all children had at least one campylobacter infection, one-third of these being associated with diarrhoea. The annual incidence of all campylobacter infections was 2.1 episodes per child. The incidence was inversely related to age (r = -0.78 p less than 0.02). The illness-to-infection ratio, which in infants younger than 6 months was 1:2, was negatively associated with age (r = -0.7, p less than 0.02). Only symptom-producing infections occurring early in life seemed to protect against subsequent infections.

High incidence of subclavian dialysis catheter-related bacteremias

This retrospective cohort study reviews the incidence of bacteremia in 48 patients undergoing hemodialysis using subclavian vein dialysis catheters (SDC) as temporary vascular access. Twelve (25%) of these patients had catheter-related bacteremia, and the most frequently isolated organisms were coagulase-negative staphylococci. Three patients developed right-sided endocarditis and one of them died due to pulmonary embolism. The presence of possible risk factors for SDC-related bacteremia, including duration of catheterization and number of hemodialysis procedures, were not statistically different when patients with and without bacteremia were compared, with the exception of a significantly lower incidence of bacteremia among those patients receiving antibiotic therapy at the time of catheter insertion. The use of resterilized catheters was not a risk factor. Specific guidelines for SDC insertion and care were established and followed, after which the infection frequency was reduced to 7.5% (1 episode per 45.5 patient-weeks of catheter use) in this high-risk population.

Control of emergence of multi-resistant gram-negative bacilli by exclusive use of amikacin

Results of a three-year prospective study of amikacin as the only aminoglycoside used at the Instituto Nacional de la Nutrición "Salvador Zubirán" are presented. During the initial three-month baseline period, resistance to amikacin, gentamicin, and tobramycin among 870 gram-negative bacterial isolates was 3.2 percent, 17.4 percent, and 11.2 percent, respectively. In this period, the overall consumption of aminoglycosides was 69 percent for gentamicin, 30.5 percent for amikacin, and 0.5 percent for tobramycin. In the following period of exclusive amikacin use, sensitivity patterns of 9,344 gram-negative strains isolated over three years were recorded. During this period, amikacin constituted 99.3 percent of all aminoglycosides used. The percentage of gentamicin-resistant gram-negative strains declined to 7.4 percent (p less than 0.0001), whereas the percentage of amikacin-resistant strains did not change significantly. Quarterly trend analysis of aminoglycoside-resistant strains also demonstrated a significant decrease in gentamicin resistance (p less than 0.005) and an overall steady state of amikacin resistance. It is concluded that the exclusive use of amikacin was not accompanied by a significant increase in amikacin resistance during a three-year period, and may even lead to a decrease in resistance to gentamicin and tobramycin among most gram-negative organisms.