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Prevalence of nosocomial infections in a secondary care hospital in Mexico

How to cite this article: Castañeda-Martínez FC, Valdespino-Padilla MG. Prevalence of nosocomial infections in a secondary care hospital in Mexico. Rev Med Inst Mex Seguro Soc. 2015 Nov-Dec;53(6):686-90.



Received: July 22nd 2014

Accepted: August 28th 2014

Prevalence of nosocomial infections in a secondary care hospital in Mexico

Fernando Cain Castañeda-Martínez,a María Guadalupe Valdespino-Padillab

aDepartamento de Epidemiología, Unidad de Medicina Familiar No 82, Instituto Mexicano del Seguro Social, Zamora, Michoacán, México

bDepartamento de Epidemiología, Hospital General de Zona con Medicina Familiar No 2, Instituto Mexicano del Seguro Social, Zacapu, Michoacán, México

Communication with: Fernando Cain Castañeda-Martínez

Telephone: (351) 119 4388, (753) 142 8727

Correos electrónicos:;

Background: Nosocomial infections are a growing problem of great social and economic impact that affects hospitals. The aim of this study was to determine the prevalence of nosocomial infections in a secondary care hospital.

Methods: A cross-sectional, observational study. Sample size was calculated for a proportion, hospitalized patients with more than 48 hours of stay were included; descriptive statistics and hypothesis testing was done using Fisher’s exact test; SPSS software version 18 was used.

Results: A prevalence of 9.52% was found, with an average age of 46.59 years; 64.3% of patients were female, 35.7% male. The prevalence was 16.27% in Internal Medicine department and 12.5% Surgery.

Conclusions: 10 out of 100 hospitalized patients develop nosocomial infection, similar to that reported in the literature.

Keywords: Cross infection, Prevalence, Family practice, Epidemiology.


Infections related to patient care in hospital areas have been around since the advent of hospitals themselves.1 Nosocomial infections (NI) are an important public health problem worldwide, and are of great social and economic impact.2,13,14 There is concern about NI in all countries; they constitute a permanent risk of healthcare, with significant impact on hospital stay and costs.3 These infections are associated with multiple factors;4 scientific and methodological trends on safety and quality of care suggest enhancing NI prevention,5 as they are the most common hospital complication, even in the context of the developed world. In European countries, for example, a prevalence of 3-6% is reported, with high impact on mortality.6 Mexico has an estimated nosocomial infection rate between 3.8 and 26.1 per 100 discharges.7,8,21 In some hospitals in Mexico, there has been an increased prevalence of NI in internal medicine, pediatrics, surgery, and to a lesser extent in gynecology-obstetrics.9 Knowledge of the prevalence of NI and its associated factors can prevent up to a third of nosocomial infections.10 NI is defined, according to the CDC (Centers for Disease Control) of the United States, as a systemic or localized condition observed during or immediately after a hospital stay, resulting in an adverse reaction to the presence of an infectious agent or its products, without evidence that the infection was present or incubating at the time of admission.11,12 In Mexico, the Comité de Detección y Control de Infecciones Nosocomiales (CODECIN) was created for the epidemiological surveillance of NI, being an entity composed of nurses, epidemiologists and/or infectious disease specialists, clinicians, health service managers, and other relevant areas such as microbiology, pharmacy, etc, that coordinates the activities of detection, investigation, recording, reporting, and information analysis, in addition to training for the detection, management, and control of NI.12 The prevalence found in a Unidad Médica de Alta Especialidad of the Hospital de Pediatría of the Centro Médico Nacional del Occidente of the Instituto Mexicano del Seguro Social (IMSS), in July 2013, was 11.6%.15

The estimates, based on prevalence data, indicate that NI doubles the burden of nursing care, triples the cost of medicines, and increases seven-fold the exams to be done.16 For control programs to be successful, it is necessary to understand the epidemiology of these infections, their prevalence, causal microorganisms, and associated risk factors. For example, it has been observed that knowledge of infection rates is very important for control policies to be effective.17,18 Nosocomial infections remain a major cause of mortality in the world. In Mexico, in institutions of secondary and tertiary care, overall mortality associated with NI is recorded at 4.8%.19,20 Determining the prevalence of nosocomial infections serves as a guideline for future research and for the implementation of specific action plans.22


A cross-sectional, observational study was done, nested in the cohort of patients overseen by the hospital epidemiological surveillance unit (HESU), who had more than 48 hours of hospital stay. Sample size was calculated for a proportion, prevalence of 9%, 95% confidence level, and 0.05 precision,25-28 obtaining a sample size of 126 patients; the study was conducted in 2013 in the HGZ/MF 3 of the Instituto Mexicano del Seguro Social based in Salamanca, Guanajuato. The certificate of registration of cases of nosocomial infection was applied to all patients who met the inclusion criteria. The information was gathered by the staff responsible for HESU, composed of two epidemiology doctors, a general nurse, and a nursing intern. The information was captured in an Excel database for later analysis with the statistical software SPSS version 18, obtaining frequency measures, measures of association, measures of potential impact, and hypothesis testing using Fisher's exact test. 


Of the 126 patients of the calculated sample who met the inclusion criteria to participate in the study, the prevalence of nosocomial infections was found at 9.52%. The average age of the patients studied was 46.59 years (SD = 18.9). 64.3% were women and 35.7% men. Regarding factors analyzed associated with NI, it is observed that 46.0% of patients were in an immunocompromised state.

By department of hospitalization, in Internal Medicine NI prevalence was 16.27%, 12.5% ​​in Surgery, 5% in Traumatology and Orthopedics, and 3.1% in Gynecology and Obstetrics; no NI cases were found in the Pediatrics department. According to the type of nosocomial infection, 75% were related to vascular line infections, 25% were surgical site infection, and finally only 8.3% were peritonitis. Only 50% of NI cases found at the time of study had had culture taken.

The average patient stay was 4.03 days, with a standard deviation of 4.3, ranging from 3 to 9 days. During the review of medical records, it was found that 65 (51.6%) of the patients had antibiotic therapy, and 61 (48.4%) were without antibiotics. Cefotaxime was the most commonly used antibiotic, administered to 18.3% of patients who had antibiotics at the time of the study. According to the operation of the HESU, 100% of NI cases detected were already reported to the system, however only 50% of these cases were reported by the treating physician.

Measures of frequency were calculated for each of the factors associated with nosocomial infections in exposed and unexposed patients (Table I), as well as the frequency of exposure of sick and non-sick patients (Table II).

Table I Prevalence of disease (NI) in patients exposed and not exposed to different factors associated with nosocomial infections
Associated variable Prevalence of disease
Exposed Not exposed
Central catheter 3 (60%) 9 (7%)
Underwent surgery 3 (11%) 9 (9%)
5-9 days of hospital stay 6 (9.8%) 6 (9.23%)
Age 20-59 years 6 (7.5%) 6 (13%)
Age 59 years and over   6 (16.21%) 6 (6.7%)
Immunocompromised 9 (15.5%) 3 (4.41%)
Gynecology and obstetrics department 1 (3.1%) 11 (11.70%)
Surgery department 3 (12.5%) 9 (8.8%)
Internal medicine department 7 (16.27%) 5 (6.02%)
Female 10 (12.34%) 2 (4.44%)
Male 2 (4.44%) 10 (12.34%)
Source: Nosocomial infection prevalence database in HGZ/MF 03, Salamanca, Guanajuato 2013

Table II Prevalence of exposure to different factors in patients sick and not sick with nosocomial infections
Associated variable Prevalence of exposure
Sick Not sick
Central catheter 3 (25%) 2 (1%)
Underwent surgery 3 (25%) 24 (21%)
5-9 days of hospital stay 6 (50%) 55 (48.24%)
Age 20-59 years 6 (50%) 74 (64.91%)
Age 59 years and over   6 (50%) 31 (27.19%)
Immunocompromised 9 (75%) 49 (42.98%)
Gynecology and obstetrics department 1 (8.3%) 31 (27.19%)
Surgery department 3 (25%) 21 (18.42 %)
Internal medicine department 7 (58.33%) 36 (31. 57%)
Female 10 (83.33%) 71 (62.28%)
Male 2 (16. 66%) 43 (37.71%)
Source: Nosocomial infection prevalence database in HGZ/MF 03, Salamanca, Guanajuato 2013

To calculate the measure of association, the prevalence ratio of disease and exposure was obtained for each variable, and Fisher’s exact test was used to determine whether there was statistically significant association between the dependent variable (nosocomial infection) and its various associated factors.

Of the factors analyzed associated with nosocomial infection, association was only found between having a central catheter placed and the presence of nosocomial infection, with a prevalence ratio of 8.06 and a 95% confidence interval (95% CI, 3.1-20.9) (Table III).

Table III Prevalence ratio of disease and exposure in factors associated with nosocomial infections in IMSS Hospital General de Zona con Medicina Familiar 03 in Salamanca, 2013
Variable Prevalence ratio of disease CI: 95% Fisher's exact test Variable Prevalence ratio of exposure CI: 95% Fisher's exact test
Central catheter 8.06 3.1-20.9 0.006 Central catheter 14.25 2.6-77.02 0.006
Underwent surgery 1.22 0.35-4.20 0.49 Underwent surgery 1.18 0.41-3.36 0.49
5-9 days of hospital stay 1.06 0.36-3.12 0.57 5-9 days of hospital stay 1.03 0.57-1.88 0.57
Age 20-59 years 0.57 0.19-1.67 0.23 Age 20-59 years 0.77 0.43-1.37 0.23
Age 59 years and over   2.4 0.82-6.97 0.09 Age 59 years and over   1.83 0.96-3.48 0.09
Immunocompromised 3.51 0.99-12.38 0.03 Immunocompromised 1.74 1.18-2.57 0.03
Gynecology and obstetrics department 0.26 0.03-1.98 0.13 Gynecology and obstetrics department 0.3 0.04-2.04 0.13
Surgery department 1.41 0.41-4.84 0.00 Surgery department 1.35 0.47-3.89 0.4
Internal medicine department 2.7 0.91-8.01 0.06 Internal medicine department 1.84 1.06-3.19 0.06
Female 2.77 0.63-12.12 0.12 Female 1.33 1.00-1.78 0.12
Male 0.36 0.08-1 57 0.12 Male 0.44 0.12-1.60 0.12
Source: Nosocomial infection prevalence database in HGZ/MF 03, Salamanca, Guanajuato 2013

For measures of potential impact, the etiological fraction was calculated in exposed patients, in which it was noted that if placement and general care of a central catheter were carried out with the safety and hygiene measures recommended by the World Health Organization, 87.59% of cases of nosocomial infections would be avoided in patients exposed to this.


Nosocomial infections remain a public health problem that requires the preventative actions of a multidisciplinary team to control it. This study represented a major effort to quantify the prevalence of nosocomial infections in HGZ/MF 3 in Salamanca, Guanajuato, a secondary care hospital with 60 hospital beds. According to the results obtained in this study, 10 out of every 100 patients hospitalized at this unit acquire an NI, a figure that is consistent with reports from other studies at national and international levels.

It is recommended to practice the hand hygiene proposed by the WHO, emphasizing the five stages (International Patient Safety Goal No. 5) as a measure of prevention and control to decrease NI.

The association between central catheter and the presence of nosocomial infection is 8.06 times higher in patients who had this device placed, compared with those who did not have it, which is statistically significant (95% CI, 3.1-20.9).

The use of antibiotic regimens is essential for secondary hospitals and tertiary care, hence the importance of having a committee to regulate the use and abuse of these drugs to prevent the hospital environment from fostering the presence of more nosocomial infections.

This report indicates that it is feasible to have one’s own statistics for nosocomial infections, to detect deviations, and to implement the necessary measures to prevent and control nosocomial infections in the IMSS Hospital General de Zona con Medicina Familiar 03, in Salamanca, Guanajuato.

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Conflict of interest statement: The authors have completed and submitted the form translated into Spanish for the declaration of potential conflicts of interest of the International Committee of Medical Journal Editors, and none were reported in relation to this article.

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