IgG subclasses against Helicobacter pylori isolates: an important tool for disease characterization

Helicobacter pylori infects around 50% of the world's population and is associated with diverse pathologies. In the most severe cases, the bacterium causes peptic ulcers and gastric cancer. The interplay between H. pylori and the host's immune response may help to determine the specific outcome of the infection. To study the relationship between antibody subclasses and variation in immune recognition, we determined the immunoglobulin G1 and 2 (IgG1 and IgG2) titres of sera obtained from patients with different H. pylori-associated pathologies. IgG1 and IgG2 titres were determined by ELISA in 44 sera of patients with different H. pylori-associated diseases (peptic ulcer, bleeding peptic ulcers, gastric cancer and dyspepsia). Soluble proteins from lysates were obtained from 12 different clinical isolates from similar associated diseases. We found that soluble proteins from lysates of H. pylori strains (SPLHP) recognition patterns in these sera were highly variable. Overall, IgG2 titres were higher than the IgG1 titres in the infected patients. In particular, those with peptic ulcers showed marked elevation in IgG2/IgG1 ratios, while SPLHPs from dyspeptic patients resulted in high IgG1 titres. Our results reveal that correlation of antibody subclass titres with Th1/Th2 markers may aid pathology characterization and show a potential diagnosis that could be formally evaluated in other studies.

[Hyperhomocysteinemia as risk factor in a Mexican population]

Hyperhomocysteinemia is considered one of the emerging risk factors for the development of coronary artery disease (CAD). In order to know the prevalence of this metabolic disorder in a Mexican population with early CAD (< 50 years), we studied a group of these patients and compared the levels of homocysteine with a group of patients, paired by age and gender, without angiographic evidence of coronary atherosclerosis. Preliminary results show that the population with early CAD has more traditional risk factors, specially diabetes mellitus, and higher levels of homocysteine in plasma. Moreover there is a genetic factor with higher incidence of a TT homozygotic mutation of the MTHFR that increases homocysteine because of an altered folate metabolism.

Helicobacter pylori and other enteric bacteria in freshwater environments in Mexico City

BACKGROUND

Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and risk factors for infection as well as mode of transmission remain unclear.

METHODS

H. pylori was detected by polymerase chain reaction (PCR) technique in three aquatic systems located in the Mexico City area. In addition, microbiologic cultures and physicochemical parameters were measured. The systems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses.

RESULTS

Twenty-one percent of the samples (16/77) were positive for H. pylori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hybridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, both providing conditions for potential survival of H. pylori and other enteric pathogens in these environments.

CONCLUSIONS

The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a vehicle in the transmission of H. pylori as well as infection by other known enteric pathogens.

[Nosocomial infections: secular trends of a control program in Mexico]

OBJECTIVE

To know the trend of nosocomial infections rates at a third level hospital since the beginning of the infection control program until the present and to evaluate the impact in mortality and length of hospital stay.

MATERIAL AND METHODS

A study descriptive, retrospective and retrolective was done in a reference hospital providing tertiary care in Mexico City. Recorded data included rates, type of nosocomial infections and distribution of nosocomial infections from the database of Hospital Epidemiology Division between 1991 to 1996. In every patient the degree of severity disease was evaluated according to the McCabe-Jackson's scale, we also collected age and the length of stay. Statistical analysis was done with chi 2 test for tendencies of different evaluated parameters. This study was divided in three periods: before remodel (1991-1993), to remodel (1994-1995) and after remodel (1996). Compared the before remodel period against after remodel period.

RESULTS

In the study period, mean nosocomial infections ratio was of 8.6 by 100 discharges, showing a decrease of 20% (p < 0.01). Hospital area with the highest infections rate was ICU (26.9 by 100 discharge), followed by general ward of hospitalization with shared rooms (9.47) and private rooms (7.5). Urinary tract infections was the most frequent (26.6%), followed by surgical wound infection (24.4%), pneumonia (12.1%) and primary bacteremia (9.5%). Rates of urinary tract infections and primary bacteremias had decreased significantly (p < 0.05 and p < 0.00001 respectively), while surgical wound infections and pneumonias increased (p < 0.005 and p < 0.00001 respectively). Associated mortality diminished in 36% (p < 0.00001). The length of stay diminished 42.8%. There was not differences in the severity of disease along this period.

CONCLUSIONS

Since the establishment of the nosocomial infections surveillance and control program at the INNSZ on 1985, nosocomial infections rate (56%) and the associated mortality (36%) have diminished. These changes are consequence of the establishment of a nosocomial infections control program and the decrease of length of stay and does not seems to be related to the age or to the severity of the disease of the hospitalized patients.

Colonization of Mexican patients by multiple Helicobacter pylori strains with different vacA and cagA genotypes

Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Americans with H. pylori infections. We characterized the vacA (vacuolating cytotoxin gene A) and cagA (cytotoxin-associated gene A) types of more than 400 single-colony isolates from 20 patients in Mexico City. For 17 patients H. pylori strains of two or more different vacA genotypes were isolated from gastric biopsy specimens, indicating infection with two or more strains of H. pylori. The most frequent vacA genotype was s1b/m1. vacA diversity was more marked than that described previously, in that isolates from seven patients had untypeable vacA midregions and isolates from nine patients had type s1 signal sequence coding regions which could not be further subtyped. Previously undescribed vacA type s2/m1 strains were found in five patients. All patients were infected with cagA-positive strains, but occasionally, these coexisted with small numbers of cagA-negative strains. In conclusion, coinfection with multiple H. pylori strains is common in Mexico, and vacA in these strains is genetically more diverse than has been described in other populations.

An epidemic outbreak of Malassezia folliculitis in three adult patients in an intensive care unit: a previously unrecognized nosocomial infection

BACKGROUND

Malassezia is a lipophilic fungus commonly found in normal human skin. Infection of the hair follicle by Malassezia furfur occurs in patients with predisposing factors such as diabetes or immunosuppression, or who are undergoing antibiotic treatment. Malassezia furfur folliculitis is an infrequent nosocomial infection which may be associated with fomite transmission.

METHODS

We reviewed the clinical files of three adult patients from an intensive care unit (ICU) who simultaneously developed folliculitis through Malassezia infection. We specifically analysed predisposing factors, possible transmission modes, characteristics of skin lesions, results of biopsies and cultures, treatment, and patient outcome.

RESULTS

The three male patients were in neighboring beds and they all had factors that predisposed them to underlying immunosupression. Simultaneously, and within hours of each other, they developed erythematous follicular papules and pustules on the face and chest. The skin biopsies revealed an acute folliculitis with abundant round to oval yeasts of up to 5 microm in diameter. Stains for fungi (Schiff's peryodic acid, Grocott and silver methenamine) revealed numerous unipolar budding yeasts without hyphae, consistent with M. furfur. Conventional cultures were negative. The diagnosis of folliculitis by M. furfur was established and antifinigal treatment initiated, with adequate outcome of the dermatosis. After this outbreak, the aseptic and hygienic measures of the health care personnel of the ICU were reviewed and corrected.

CONCLUSIONS

The simultaneous emergence of this superficial infection by M. furfur suggests fomite participation. This dermatomycosis is an infrequent nosocomial infection in adults, which to our knowledge has not been previously reported.

Bronchoaspiration as a possible cause in a case of tetanus. A reminder on the importance of adulthood immunizations

Although preventable by immunization tetanus still takes a large death toll, mostly in developing countries, where adult population is often unprotected and opportune medical care unavailable. We present a case of tetanus in an elderly patient with bronchoaspiration pneumonia after a near-drowning incident, in which no objective entry site could be suspected with as much temporal relation as the bronchoaspiration incident. Bronchoaspiration of organic matter and feces provides both a source of the causative agent and an adequate polymicrobial environment for the development of the disease. It is under such conditions that we propose this unusual entry site as the cause of tetanus in our patient. Special emphasis is made on the importance of adulthood immunization programs and how incidents like this one should be taken into account in the overall care provided to the elderly population.

Prognostic value of oral candidosis and hairy leukoplakia in 111 Mexican HIV-infected patients

A follow-up study was carried out to evaluate the prognostic value of hairy leukoplakia (HL) and oral candidosis (OC) in a cohort of 111 asymptomatic Mexican HIV infected patients. Oral exams were performed at baseline and every 6 months, from September 1989 to March 1994. Chi-square contingency table test, the Kruskall-Wallis one-way analysis of variance, the Kaplan-Meier product-limit method and the log rank test were used for the analysis. Univariate and multivariate Cox's proportional hazards analysis were also performed. Fifty-four patients (51%) progressed to AIDS (initially 36 CDC-II and 18 CDC-III). Individuals with HL and/or OC, showed faster development to AIDS than subjects without lesions or other HIV-related manifestations (P = 0.008). The presence of OC, HL or both always remained significant despite adjustment for total lymphocytes, CDC stage, zidovudine therapy or its combinations. Oral lesions in HIV infection may be regarded with other clinical and laboratory studies as markers of HIV disease progression and as indicators to begin antiretroviral treatment.

[Conceptualization and measurement of the quality of life of cancer patients]

We have reviewed three attributes related with quality of life of cancer patients: definition, objectives and methods of measurement. The definition most widely accepted is that quality of life is the "subjective evaluation of life as good or satisfactory as a whole". It is proposed that quality of life should be included as an outcome variable in clinical trials, especially in palliative care; in addition it could be useful in clinical decisions and in planning care for cancer patients. Finally we have reviewed critically several scales that are being used for the measurement of quality of life of cancer patients.

[The risk factors in primary bacteremias: a case-control study]

Nosocomial bacteremias are a important cause of mobility and mortality for hospitalized patients which, in addition, generate additional and elevated costs to the institutions. Its frequency has increased in the last year in relation to a greater number of patients, many of them immunosuppressed, which are submitted to invasive procedures. In this study, we analyzed the primary nosocomial bacteremias which occurred in our institution, carrying out a comparative case and control study in order to find the main risk factors which condition their occurrence. In a period of 42 months, 83 episodes of nosocomial primary bacteremias were detected. These represented an incidence of 8 per 1000 of patients which left the hospital and with a clear rising incidence in the last six months. In the Intensive Care Unit (ICU) a greater rate was found per sector (21.3 x 1000). The predominating agents were S. epidermidis, enterobacteremia, S. aureus and enteroccocci. Of the 15 possible risk factors analyzed by multiple regression, those significant were over two weeks of hospital stay and the use of parenteral feeding. These results make it imperative to reinforce control measures in the preparation of parental feeding solutions as in patients with prolonged hospital stay, especially in the ICU.

[Change in the quality of life as an indicator of the clinical course of disease. Comparison of 2 indices]

Quality of life is an important outcome measurement to judge disease impact and response to treatment; however it is very difficult to measure. We compared the MacKenzie's Change in Maximal Function Index (CMFI) with the Change in Quality of Life Index (CQLI) developed by our group. Both indices were applied on admission and upon discharge of 23 medical and surgical inpatients. The CQLI's interobserver reliability was somewhat better (Ri = 0.69) than that of the CMFI (Kw = 0.49). Both indices correlated with patient, close relative and physician assessments (rs = 0.52 to 0.86, p < 0.05). There was no correlation with Karnofsky scores. Both showed adequate responsiveness with Guyatt's coefficients between 2 and 4. Ninety five percent of the patients thought the questionnaires were easy to answer and approximately 5 minutes were enough to complete them. Both indices seem to perform better when applied by a social worker than when applied by a physician. Our results suggest that it is feasible to obtain consistent estimates of changes in quality of life. Either one of these indices may be used to assess the impact of medical intervention.

[T CD4+ cell counts and their use in the management of patients with HIV-1]

The hallmark of the HIV-1 infection is the progressive depletion of the circulating CD4+ T cells. The prophylactic, therapeutic and prognosis criteria of the HIV-1 infected patients are based on the measurement of these cells. However, there are serious analytical and biological variations in the count of CD4+T cells. The factors that influence the measurement of the circulating levels of CD4+T cells and its consequences in the clinical management of the HIV-1 infected patients are described in this update. In addition, some recommendations are suggested to reduce these variations.

[The seroepidemiology of rubella in a female population of reproductive age in León, Guanajuato]

In order to assess the seroepidemiology of protective antibodies against rubella among women from León, Guanajuato, Mexico, a prospective study was done. The sample consisted in 176 serum samples from urban and rural women at reproductive age, drawn from June 1990 to June 1991. Samples were tested by the classic hemagglutination inhibition method, titers of 1:8 or higher were considered as positive. Global positivity was 71 per cent (125 sera). Seropositivity did not increase with women's age; the lowest values were seen at the rural zones (58.9%). This survey showed a lower seropositivity than the previously reported in Mexico, and confirms data from new official studies. With this information authors suggest that the utility and viability of a national vaccination program should be reviewed and propose that it could be risky that individual clinicians to recommend children vaccination because the lack of coordination could increase adult cases of rubella.

Transfusion associated AIDS in Mexico. Clinical spectrum, conditional latency distribution, and survival

There is very little information on the clinical spectrum and the incubation period among AIDS patients in Latin America. This study reports the clinical spectrum, survival, and the incubation period for a group of Mexican patients infected with HIV-1 as a result of contaminated blood transfusion. We analyzed data from 39 patients of whom date of transfusion and diagnosis were known. The clinical spectrum of the disease was compared with a group of AIDS Mexican patients infected by sexual route. The prevalence distribution of opportunistic infections was similar in both groups. However, there was a significant difference in the distribution of opportunistic malignancies, i.e., Kaposi's sarcoma was observed only in the homosexual group. AIDS developed within 48 months after infection (3% within 12 months after transfusion, 50% within 29 months, 75% within 36 months, and the remaining within four years). The mean survival was of nine months after AIDS is made, the survival in this group of AIDS Mexican patients was similar to that observed in other HIV-1 exposed risk groups in Mexico. These findings suggest that the route of exposure to HIV-1 may have prognostic implications in the natural history of this infection in the Mexican population.

Major recurrent oral ulcers in AIDS: report of three cases

We report the cases of three AIDS patients who developed major recurrent oral ulcers with severe odynophagia and weight loss. The patients were treated successfully with systemic steroids. Within the first week of prednisone therapy (40 mg/day), the symptoms improved and the lesions entirely healed. We suggest, on the bases of recent literature, that superantigens and the cytokine network could be involved and they should be considered in the immunopathogenic mechanisms of this type of ulcers.

The spectrum of clinical and pathological manifestations of AIDS in a consecutive series of autopsied patients in Mexico

OBJECTIVE

Little is known about the clinical profile of AIDS in Latin American populations. This study characterizes the clinical and pathological manifestations of AIDS in a representative series of Mexican AIDS patients at autopsy.

DESIGN

The clinical and pathological findings were abstracted retrospectively for a sequential series of autopsied AIDS patients.

SETTING

Autopsies were conducted at the four major tertiary level hospitals that serve the majority of AIDS patients in Mexico City.

PATIENTS

Subjects included 177 consecutive patients diagnosed with AIDS between March 1984 and January 1989 who subsequently died and were autopsied in the same period in the study hospitals.

MAIN OUTCOME MEASURES

Demographic characteristics, including age, gender, residence, socioeconomic status, and risk group; clinical presentation and autopsy findings, including opportunistic infections and malignancies.

RESULTS

Sixty per cent of the AIDS patients presented with wasting syndrome. The most common infections were cytomegalovirus (69%), tuberculosis (25%), and Pneumocystis carinii pneumonia (24%). Central nervous system infections were also common and included toxoplasmosis (19%) and cryptococcoses (10%). Kaposi's sarcoma was present in 30% of cases and non-Hodgkin's lymphoma in 9%.

CONCLUSION

Clinical manifestation, and types and frequency of opportunistic infections in our Mexican AIDS patients were more similar to those seen in AIDS patients in Africa and Haiti than in the United States and Europe. These findings suggest that the AIDS epidemic in Mexico has an 'intermediate' pattern and may be a prototype for Latin American countries.

[Oral pathology in 161 asymptomatic and symptomatic HIV-positive patients]

The aim of this study was to establish the prevalence of oral manifestations in HIV-infected patients and to correlate their frequency with the clinical stage. One hundred and sixty one HIV-positive individuals were examined, of whom 64 (40%) were in stages CDC-II and III and 97 (60%) in stage CDC-IV. The patients were examined at the AIDS out-patient clinic of the Instituto Nacional de la Nutrición Salvador Zubirán. The oral exams were performed by three examiners who were intra and inter calibrated, so that standard clinical criteria were followed. One hundred and twenty five patients (78%) showed one or more oral lesions. The proportion of patients with oral lesions increased significantly (p less than 0.05) according to the severity of the infection. Hairy leukoplakia (40%) and erythematous candidiasis (31%) were the most frequent lesions. When the prevalence of the different oral lesions was compared between the patients at early stages with the patients at the late stage no significant differences were found; only the pseudomembranous candidiasis and the exfoliative cheilitis were found with significantly higher values at stage CDC-IV than at earlier stages (p less than 0.001 and p less than 0.05 respectively). No association was found between oral candidiasis and tobacco use or xerostomia. Our study demonstrates that the prevalence and clinical features of the oral manifestations found showed similarities with those reported in other countries, but ulcero-necrotizing gingivitis was not found in our patients.

[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.

Oral lesions in Mexican HIV-infected patients

One hundred and twenty-five HIV-infected patients, of whom 49 (39%) were at early stages of the infection (CDC-II & III) and 76 (61%) in CDC IV, were prospectively examined. In 100 (80%) one or more oral mucosal lesions were observed; candidiasis (51%) and hairy leukoplakia (43%) were the commonest. Erythematous candidiasis was more often seen (35%) than the pseudomembranous type (16%), and appeared with the higher values at early than later stages. The prevalence of hairy leukoplakia, oral hyperpigmentation and xerostomia were incremented in groups CDC-IV. Pseudomembranous candidiasis and exfoliative cheilitis increased significantly with severity of disease. Our study demonstrates that oral alterations associated to HIV are a frequent finding, both at early (76%) and late (83%) stages of the infection in Mexican patients.

[Prognosis of intrahospital cardiorespiratory arrest. Experience at a referral center for internal medicine and surgery]

In order to identify prognostic features associated with in-hospital cardiopulmonary arrest (CPA) a prospective study was designed. A total of 130 first episodes of CPA were seen during a 6 month period. In 34 cases (26%) cardiopulmonary resuscitation (CPR) was attempted and 17 showed a positive response (recovery of cardiac automatism for more than 15 min). Median survival time in those who recovered was 38 hr. Only two patients were discharged alive from the hospital. Practice of CPR was strongly and inversely associated with the degree of anticipation on the occurrence of CPA held by the physician in charge. Age was the only variable prognostically associated with response to CPR, being the younger group (less than 40 yr) those with the worst prognosis. Aside of age and the possible beneficial effect of infection, there were no other demographic, clinical, therapeutic or other circumstances of the episode associated with response to CPR. The need of response systems to CPA, always in standby and reiterative training, is stressed.

Antiphospholipid antibodies and the antiphospholipid syndrome in systemic lupus erythematosus. A prospective analysis of 500 consecutive patients

Five hundred consecutive patients with systemic lupus erythematosus (SLE) were entered into a prospective study of anticardiolipin antibodies (ACLA) in their 3 major immunoglobulin isotypes and followed thereafter with repeated testing for a mean period of nearly 8 months. Manifestations of SLE that were strongly associated with ACLA included venous thrombosis (particularly when recurrent), thrombocytopenia, hemolytic anemia, recurrent fetal loss, and leg ulcers. Other manifestations found to be associated with ACLA were arterial occlusions, transverse myelitis, and pulmonary hypertension. Conversely, we found no relationship between ACLA and migraine, convulsions, transient ischemic attacks, psychoses, or avascular necrosis of bone. No relationship was found between the presence of ACLA and that of anti-DNA antibodies studied in the same serum sample. Association with ACLA grew stronger and titers became higher in patients with several of the associated manifestations. Statistical analyses revealed the existence of a syndrome, the antiphospholipid syndrome, comprising 2 or more manifestations in conjunction with ACLA titers 5 standard deviations above the mean of normal control subjects, particularly if ACLA had been positive on at least 2 occasions. We propose that such criteria could be applied to the definition of the antiphospholipid syndrome. The presence and the titers of these antibodies related to disease activity and titer decreased by treatment, particularly when they were of the IgM isotype. Patients in whom a thrombotic episode occurred during the course of the study were observed to have a coincident decrease in ACLA titers, a finding that might indicate consumption of the antibody during the event. Treatment and the resulting inactivation of disease appear to have independent effects on ACLA titers. Physicians should therefore be cautious in prescribing high doses of corticosteroids or immunosuppressants to patients with SLE solely because they have high titers of ACLA.

Hemocytopenia in systemic lupus erythematosus. Relationship to antiphospholipid antibodies

We studied 500 consecutive patients with systemic lupus erythematosus (SLE) for antibodies to phospholipids (APLA) by an ELISA method using cardiolipin as antigen and antiimmunoglobulins G, M and A to determine their isotype. Once entered into this prospective study the patients were followed for up to 16 months (mean 7.7 +/- 4.72 SD) with periodic determinations of APLA. Of the 500 patients with SLE, 88 had had thrombocytopenia, 25 had had hemolytic anemia, 25 had had both, and 362 had no history of these hemocytopenias. If we considered the odds ratio of these 362 patients for having high titer APLA as 1, patients with a history of thrombocytopenia, hemolytic anemia or both had significantly higher odds ratios of having APLA than did those without hemocytopenia. Patients with thrombocytopenia had significantly higher levels of IgG APLA, those with hemolytic anemia had significantly higher titers of IgM APLA and patients with both had significantly higher titers of both of these APLA isotypes, than did patients without hemocytopenias. A correlation between positive direct Coombs' tests and IgM APLA was also found. We conclude that APLA is associated with these hemocytopenias in SLE. This might be due to their interaction with negatively charged phospholipids in the cell walls of the respective cells.

Epidemic of Serratia marcescens bacteremia and meningitis in a neonatal unit in Mexico City

A case-control study was conducted on an epidemic of bacteremia and meningitis caused by Serratia marcescens in the neonatal intensive care unit and special care nursery of a general hospital in Mexico City, Mexico. A 19.9% incidence of bacteremia and meningitis was recorded in contrast to 1.4% and 3.7% during preepidemic and post-epidemic periods; a 69% mortality rate was observed. Peripheral IV catheters and the use of mixed IV fluids prepared in the wards were the major risk factors (P less than 0.001). Rectal and nasopharyngeal cultures were positive in 68% of asymptomatic neonates and hand cultures were positive in 16.7% of personnel. Strains were resistant to all aminoglycosides and broad-spectrum penicillins, and belonged to the A5/8 biogroup. Containment of this outbreak was difficult because of failure to identify colonized infants early in the epidemic and because of persistent carriage of S marcescens by personnel. Comparisons between this hospital and tertiary care centers in Mexico suggest that in developing countries nosocomial infections could be of greater magnitude in secondary than in tertiary level centers.

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.