Table 1. Relevant and related studies on the effect of meteorological factors and geographical location on MRSA and VRE colonization rates.
| Sites | Population | Study period | Colonization vs. infection | Study objective | Related statistical analysis | Related findings | |
|---|---|---|---|---|---|---|---|
| MRSA (S.aureus) | |||||||
| Ogawa, 1994 [14] | Single | Children and adults | June to August 1993 | Colonization or infection | To compare Staphylococcal flora on the skin surface of atopic dermatitis patients and healthy subjects. | Student’s T test | -A significant seasonal difference on S. aureus carriage in the forearms of atopic dermatitis patients was observed. -More S. aureus carriage was observed in the summer compared to winter. |
| Harrison, 1999 [15] | Single | Children | One year | Colonization | To determine the effect of age, gender, season, viral upper respiratory tract infection, and sleeping position on the composition of the nasopharyngeal flora in infancy. | Chi square | -No significant association between seasonality and S. aureus carriage was observed. -More carriage was observed in autumn/winter months. |
| Kaier, 2010[16] | 2 large university hospitals in Germany | N.S | January 2005 to May 2009 | Colonization and infection | To determine whether there was seasonality in the incidence of extended-spectrum β-lactamase-producing bacteria and MRSA carriage. | Time-series analysis | -No association between MRSA and temperature was detected. |
| Eber, 2011 [3] | 132 US hospitals | N.S | January 1999 to September 2006 | Infection | To evaluate seasonal changes in the frequencies of BSIs. | -Time-series analysis: models were adjusted by the nine US Census Bureau regional divisions | -No significant difference across seasons for S. aureus was observed. -An increase of 5.6°C (10°F) was associated with an adjusted increase of 2.2% in frequency of S. aureus associated BSIs. -A one-inch increase in monthly precipitation was associated with 0.3% lower frequency of S. aureus associated BSIs. -No significant association between S. aureus and humidity. |
| Perencevich, 2008 [4] | University of Maryland Medical Center | Adults | January 1998 to December 2005 | Infection | To assess whether seasonal variation existed in incidence of infection and to quantify the relationship between temperature changes and infection rates. | -Time-series analysis | -No summer peaks for S. aureus were observed. -No association between temperature and S.aureus was described. |
| Klein, 2013 [17] | S.aureus isolates across US inpatients | Children and adults | January 2005 to December 2008 | Infection | To estimate the incidence and patterns of hospital-acquired (HA) -MRSA and community-acquired (CA)-MRSA-related hospitalizations, as well as the influence of seasonal variations. | -Seasonal trend decomposition method. | -CA-MRSA incidence peaked in late summer, particularly in children. -HA-MRSA incidence peaked in the winter. |
| Wang, 2013 [18] | Maricopa County, Arizona | Children | January 2005 to December 2008 | Infection | To determine the temporal trend, seasonality pattern, and peak timing of MRSA infections in different children’s age groups. | -Time-series analysis and non-linear regression analysis | -A strong annual seasonal pattern of skin and soft tissue infection (SSTI) incidence was observed with peaks occurring in September. -A significant direct correlation between SSTI incidence and mean temperature. was observed. The same was observed for humidity. |
| Schwab, 2014 [5] | 73 German ICUs | Adult | January 2001 to December 2012 | Colonization and infection | To look for temperature associations with pathogens in a network of geographically variant sites. | -Time series analysis: location was not included in the models. | -An increase of 5°C during the prior month to isolation was associated with a 1% decrease of S. aureus. |
| Sahoo, 2014 [8] | Katalinga Institute of Medical Science in India | Children and adults | July 2009 to December 2010 | Infection | To analyze the association of S. aureus and MRSA SSTI with local temperature and relative humidity | -Time-series analysis | -An increase of 1.7°C in maximum temperature and a 10% increase in RH was associated with one unit increase in MRSA occurrence. |
| Giuffre, 2015 [12] | 1 NICU in Italy | Neonates | June 2009 to June 2013 | Colonization | To describe epidemiologic features and identify risk factors for MRSA acquisition in a level III Neonatal ICU. | -Chi square | -A seasonal variation was evident for MRSA colonization with incidence density peaking in the summer and autumn quarters (June-November). |
| Albernoor, 2016 [19] | 97 cohort studies | Adults | - | Infection | To summarize the frequency of mediastinitis following open-heart surgery caused by Gram-positive bacteria and the effect of several moderator variables including latitude | -Meta-analysis, meta-regression models | -A negative association between the frequency of mediastinitis and latitude of study site was observed. |
| VRE | |||||||
| Dauner, 2000 (abstract) [20] | Hospitals, physicians and/or laboratories in Arizona | Adults and children | January 1998 to December 1999. | Colonization and infection | To determine age and county specific incidence rates for VRE | -Estimation of age and county specific incidence rates for VRE | -No seasonal variation was observed in either year. |
| Hufnagel, 2007 [13] | 1 NICU in Germany | Neonates | March 2003 to February 2004 | Colonization | To analyze predictors for early enterococcal colonization of infants in a NICU and to describe risk factors associated with multidrug resistant enterococci colonization and its seasonal patterns. | Chi-square, logistic regression | -A significantly higher number of Enterococci and multi-drug resistant enterococci was observed during winter/spring months. |
N.S. = Not specified in the abstract/manuscript